A METHODOLOGY FOR PLANNING ROAD BEST MANAGEMENT PRACTICE S

COMBINING WEPP: ROAD EROSION MODELING AND SIMULATED

ANNEALING OPTIMIZATION

By

JAMES ANDERSON EFTA

B.S. Resource Conservation

, The University of Montana

, Missoula

, MT

, 2006

Thesis

presented in partial fulfillment of the requirements

for the degree of

Master of Science

in Forestry

The University of Montana

Missoula, MT

August 2009

Approved by:

Perry Brown, Associate Provost for G raduate Education

Graduate School

Woodam Chung, Chair

Department of Forest Management, College of Forestry and Conservation

Solomon Dobrowski

Department of Ecosystem and Conservations Sciences, College of Forestry and

Conservation

Andrew Wilcox

Department of Geosciencesii Efta, James, M.S., Summer 2009 Forestry

A Methodology for Planning Road Best Management Practices Combining WEPP: Road

Erosion Modeling and Simulated Annealing Optimization

Chairperson: Woodam Chung

E r o s i o n f r o m f o r e s t r o a d s i s a k n o w n p r o b l e m i n m o u n t a i n o u s t e r r a i n

. T o a b a t e t h e s e

n e g a t i v e c o n s e q u e n c e s

, p h y s i c a l B e s t M a n a g e m e n t P r a c t i c e s ( B M P s ) a r e i m p l e m e n t e d

,

s o m e t i m e s w i t h n o k n o w l e d g e o f e r o s i o n h o t s p o t s

. W i t h t h e n e e d t o m i n i m i z e w a t e r

q u a l i t y i m p a c t s w hile a t t h e s a m e t i m e a c c o u n t i n g f o r m u l t i p l e c o n s i d e r a t i o n s and

constraints

, road B M P p l a n n i n g a t t h e w a t e r s h e d s c a l e i s a d i f f i c u l t t a s k

. T o a s s i s t i n t h i s

p l a n n i n g p r o c e s s

, a m e t h o d o l o g y i s p r e s e n t e d h e r e t h a t c o m b i n e s W E P P : R o a d e r o s i o n

p r e d i c t i o n s w i t h s i m u l a t e d a nne a l i n g o p t i m i z a t i o n

. U n d e r t h i s m e t h o d o l o g y

, e r o s i o n

p r e d i c t i o n s a s s o c i a t e d w i t h B M P o p t i o n s f o r a s e g m e n t c o m p r i s e t h e o b j e c t i v e f u n c t i o n

o f a n o p t i m i z a t i o n p r o b l e m

. T h i s m e t h o d o l o g y w a s t e s t e d o n a w a t e r s h e d i n t h e L a k e

T a h o e B a s i n

. W E P P : R o a d i n p u t d a t a w a s g a t h e r e d t h r o u g h r o a d s u r v e y s

. M o d e l i n g

r e s u l t s p r e d i c t e d r e l a t i v e l y l i t t l e s e d i m e n t l e a v i n g t h e f o r e s t b u f f e r

, a s a r e s u l t o f

n u m e r o u s w e l l

- m a i n t a i n e d B M P s a n d t h e d r y c l i m a t e f o u n d i n t h e w a t e r s h e d

. A

s e n s i t i v i t y a n a l y s i s f o r a l l W E P P : R o a d i n p u t p a r a m e t e r s i s p r e s e n t e d

, w h i c h p r o v i d e s

i n s i g h t i n t o t h e general a p p l i c a b i l i t y o f t h e s e e r o s i o n e s t i m a t e s a s w e l l a s t h e r e l a t i v e

i m p o r t a n c e o f e a c h i n p u t p a r a m e t e r

. A f t e r e v a l u a t i n g e r o s i o n r i s k a c r o s s t h e e n t i r e

watershed, a p p l i c a b l e B M P s w e r e a s s i g n e d t o p r o b l e m r o a d s e g m e n t s a n d W E P P : R o a d

w a s u s e d t o p r e d i c t c h a n g e i n s e d i m e n t l e a v i n g t h e b u f f e r w i t h B M P i m p l e m e n t a t i o n a t a

g i v e n s i t e

. T h e s e p r e d i c t i o n s

, c o m b i n e d w i t h b u d g e t c o n s t r a i n t s a s w e l l a s e q u i p m e n t

scheduling considerations, we re incorp orated into an algorithm using simulated a nnealing

a s i t s optimization e n g i n e

. T h r e e m o d e l e d s c e n a r i o s d e m o n s t r a t e t h e v i a b i l i t y o f t h i s

m e t h o d o l o g y i n r e d u c i n g t o t a l s e d i m e n t l e a v i n g t h e r o a d b u f f e r o v e r a p l a n n i n g h o r i z o n

. O f t h e 1 7 3 segments s u r v e y e d

, 3 8 s e g m e n t s c o u l d b e t r e a t e d u s i n g g e n e r i c B M P s

. F o r a l l

t h r e e s c e n a r i o s

, BMP

- S A r e d u c e d s e d i m e n t l e a v i n g t h e b u f f e r b y a s m u c h a s 7 0 % o v e r

t h e c o u r s e o f a 2 0

- y e a r p l a n n i n g h o r i z o n

. F o r t h e 3 8 s e g m e n t s t r e a t e d w i t h B M P s

,

s e d i m e n t w a s r e d u c e d b y g r e a t e r t h a n 9 0 % o v e r t h e p l a n n i n g h o r i z o n

. T h i s m e t h o d o l o g y

i s a v i a b l e a p p r o a c h f o r s t r e a m l i n i n g w a t e r s h e d

- s c a l e r o a d n e t w o r k B M P p l a n n i n g

, despite its heavy reliance on road erosion estimates.iii ACKNOWLEDGEMENTS

F i r s t a n d f o r e m o s t

, I w o u l d l i k e t o t h a n k W o o d a m C h u n g f o r h i s tireless work

ethic

, c o n s t a n t w i l l i n g n e s s t o a n s w e r m y q u e s t i o n s

, a n d u n e n d i n g p a t i e n c e w i t h m e

. Your

teaching, encouragement

, a n d a d v i s i n g w i l l l o n g b e r e m e m b e r e d

. M y c o m m i t t e e

m e m b e r s

, S o l o m o n D o b r o w s k i a n d A n d r e w W i l c o x

, b o t h h a v e m y t h a n k s f o r t h e i r

instruction and feedback over the past two years.

I w o u l d a l s o l i k e t o t h a n k R a n d y F o l t z

, B i l l E l l i o t

, a n d J u n R h e e a t t h e R o c k y

M o u n t a i n R e s e a r c h S t a t i o n i n M o s c o w f o r their cooperation throug h t h e c o u r s e o f t h i s

research project

. T h e P a c i f i c S o u t h w e s t R e s e a r c h S t a t i o n

, b y p r o v i d i n g f u n d i n g

, m a d e

this research possible.

C a t h e r i n e S c h o e n

, J i m H a r r i s

, a n d P a u l P o t t s a t t h e L a k e T a h o e B a s i n

M a n a g e m e n t U n i t h a v e m y t h a n k s f o r m e e t i n g a n d c o n v e r s i n g w i t h m e o n m u l t i p l e

occasions and providing invaluable insight for my research.

T h e C o l l e g e o f F o r e s t r y a n d C o n s e r v a t i o n a t T h e U n i v e r s i t y o f M o n t a n a h a s m y

appreciation f o r p r o v i d i n g a w e l c o m i n g a n d c h a l l e n g i n g w o r k a n d l e a r n i n g environment

over the pa st six years . Faculty, staff, and fellow students, thank you.

L a s t

, b u t c e r t a i n l y n o t l e a s t

, I c a n n o t e x p r e s s e n o u g h g r a t i t u d e t o m y f a m i l y a n d

friends for their e ncouragement and support while I have pursued this degree.iv TABLE OF CONTENTS

Abstract ii

Acknowledgem ents iii

Table of Cont ents iv

List of Tables and Figures vi i

1. Introduction /Literature Review 1

1.1 Introduction 1

1.2 Literature Review 3

1

. 2a Effects of Road C onstruction 3

1.2b Factors Affecting Severity of Road I mpacts 5

1.2c Mitigation of Road Impacts U sing Best Management Practices

8

1.2d Road Erosion Prediction Using Models 11

1.2e Natural Resource Planning and Decision Support Tools 13

1.3 L iterature Review Summary 18

1.4 References 19

2

. An Analysis of WEPP: Road Parameter Sensitivity 25

2.1 Abstract 2 5

2.2 Introduction 26

2 .3 Descriptio n of WEPP: Road Interface 28

2 .4 Methods 29

2 .5 Results/Discussion 31v 2 .5 a Qualitative P arameters 31

2 .5 b Quantitative Parameters 38

2 .6 Conclusion s 40

2 .7 References 42

3

. A Methodology for Planning Road B est M anagement P ractices Combin ing WEPP:

Road Erosion Modeling and Simulate d Annealing Op timization 45

3 .1 Abstract 45

3 .2 Introduction 46

3 .3 Study Site 47

3 .4 Methods 49

3

. 4a Field data collection 49

3 .4b Data acquisition using GIS/preparation for model input 51

3 .4c “Hot spot” iden tification and verification 53

3 .4d Simulated a nnealing m o deling framework 54

3 .5 Results 60

3 .5a WEPP: Roa d erosion modeling results 60

3 .5b BMP

- SA modeling r esults 65

3.6 Discussion 72

3 .6a Discussion of WEPP: road modeling res ults 72

3 .6b Discussion of BMP

- SA modeling results 77

3.7 Conclusions 7 8

3.8 References 81vi Appendixes A

A. Example Solution from BMP

- SA Algorithm A

B. Flowchart Describing Adapted Simulated Annealing Algorithm

N

C. Example Input Table for BMP

- SA Algorithm Ovii LIST OF TABLES AND FIGURES

Tables

Table 1. WEPP: Road input parameters and possib le values or parameter ranges 29

Table 2

. Control road segment used for WEPP: Road sensitiv ity analysis 30

Table 3. WEPP: R oad co ntrol segment predictio ns 31

T a b l e 4

. C l a s s i f i c a t i o n o f r o a d s e g m e n t s w i t h g r e a t e r t h a n 0 l b s / y r s e d i m e n t l e a v i n g

buffer into risk rating classes 53

Table 5

. Priority of BMP assignment for a given road segment 56

Table 6 . Further criteria used when assigning BMPs to problematic road segments

56

T a b l e 7

. I n s t a l l a t i o n c o s t s

, m a i n t e n a n c e c o s t s

, a n d m a i n t e n a n c e f r e q u e n c i e s a s s o c i a t ed

with assigned BMPs 57

Tab l e 8

. P r e d i c t e d s e d i m e n t l e a v i n g r o a d a n d sediment l e a v i n g b u f f e r i n t o n / y r a n d

ton/acre /yr in Glenbrook Creek, NV. 61

Table 9

. F orest road erosion rates fr om multiple published studies 75

Table 10 . Reduction in predicted sediment leaving the buffer u sing BMP

- SA model

7 8

Figur es

Figure 1. Example of solution value change with iteration number in a minimization

problem using s imulat ed a nnealing optimization 17

Figure 2. WEPP: Road predictions of sediment leaving the road under four road designs

33

Figure 3. WEPP: Road predictions of sediment leaving the buffer under four road designs

33

Figure 4. WEPP: R oad predictions of sediment leaving the road under diff erent road

surface types 36viii Figure 5. WEPP: Road predictions of sediment leaving the buff er under three road

surface types 36

Figure 6. WEPP: Road predictions of sediment leaving the road under no traffic, low

traffic, and high traffic scena rios 3 7

Figure 7. WEPP: Road predictions of sediment leaving the buffer under no traffic, lo w

traffic, an d high traffic scenarios 37

Figure 8. WEPP: Road predictions of sediment leaving the road in silt loam soil under

multiple quantita tive par ameter scenarios 39

Figure 9. WEPP: Road predictions of sediment leaving the buffer in silt loam soil under

multiple quantita tive parameter scenarios 39

Figu re 10. Map of study area 48

Figure 11. E xample initial solution formulated from a list of alternativ e BMPs on a road

segment 59

Figures 12 and 13

. Examples of neighborhood solutions formulated from the initial

(current) solution 59

Figure 14 . Map of erosion risk by road segment, Glenbrook Creek forest road network

61

Figure 15 . Erosion rates for sediment leaving native surface road segm ents at various

segment lengths, Glenbrook Creek, NV. 62

Figure 16 . Erosion rates for sediment leaving native surface roads at various road

gradients, Glenbrook Creek, NV. 62

Figure 17

. Erosion rates for sediment leaving the buffer from native surface roads at

various buffer lengths, Glenbrook Creek, NV. 63

Figure 18 . Average erosion rates for three road surface types, Glenbrook Creek, NV.

6 4

Figure 19 . Average erosion rates for native surface roads in three soil types, Glenbrook

Creek, NV. 65

F i g u r e 2 0

. S e d i m e n t l e a v i n g r o a d b u f f e r t h r o u g h p l a n n i n g h o r i z o n w i t h i n c r e a s i n g i n i t i a l

budget per period, new BMP installation only model scenario. 66ix F i g u r e 2 1

. N u m b e r o f B M P s i n s t a l l e d i n p e r i o d o n e a t v a r y i n g i n i t i a l b u d g e t s p e r p e r i o d

, new BMP installation only model scenario. 66

Figure 22 . Number of BMPs installed in each period at varying initial budgets per period,

new BMP installation only model scenario. 67

F i g u r e 2 3

. S e d i m e n t l e a v i n g r o a d b u f f e r t h r o u g h p l a n n i n g h o r i z o n w i t h i n c r e a s i n g i n i t i a l

budget per period for new BMP installation and maintenance model scenario. 68

F i g u r e 2 4

. N u m b e r a n d t y p e o f B M P s i n s t a l l e d o n t r e a t a b l e r o a d s e g m e n t s a t v a r y i n g

initial budgets per period for new BMP installation and maintenance model scenario.

69

F i g u r e 2 5

. N u m b e r a n d t y p e s o f B M P s i n s t a l l e d i n p e r i o d o n e a t v a r y i n g i n i t i a l b u d g e t s

per period for new BMP installation and maintenance model scenario. 69

F i g u r e 2 6

. N u m b e r o f B M P s i n s t a l l e d i n e a c h p e r i o d a t v a r y i n g i n i t i a l b u d g e t s p e r p e r i o d

for new BMP installation and maintenance model scenario. 70

F i g u r e 2 7

. S e d i m e n t l e a v i n g b u f f e r t h r o u g h c o u r s e o f p l a n n i n g h o r i z o n a t v a r y i n g i n i t i a l

b u d g e t s p e r p e r i o d f o r e x i s t i n g B M P m a i n t e n a n c e

, n e w B M P i n s t a l l a t i o n

, a n d n e w B M P

maintenance model scenario. 71

F i g u r e 2 8

. N u m b e r a n d t y p e o f B M P s i n s t a l l e d i n p e r i o d o n e a t v a r y i n g i n i t i a l b u d g e t s

p e r p e r i o d f o r e x i s t i n g B M P m a i n t e n a n c e

, n e w B M P i n s t a l l a t i o n

, a n d n e w B M P

maintenance model scenario. 71

F i g u r e 2 9

. N u m b e r o f B M P s i n s t a l l e d p e r p e r i o d a t v a r y i n g i n i t i a l b u d g e t s p e r p e r i o d f o r

e x i s t i n g B M P m a i n t e n a n c e

, n e w B M P i n s t a l l a t i o n

, a n d n e w B M P m a i n t e n a n c e m o d e l

scenario. 721 1. INTRODUCTION /LITERATURE REVIEW

1.1 Introduction

F o r e s t r o a d s f u l f i l l a c r i t i c a l s e r v i c e t h r o u g h p r o v i d i n g a c c e s s t o p u b l i c l a n d s

. I f

r o a d m i l e a g e i s a m e t r i c o f p e r c e i v e d i m p o r t a n c e o f r e m o t e l a n d a c c e s s

, t h e 3 8 0

, 0 0 0

m i l e s o f U n i t e d S t a t e s F o r e s t S e r v i c e ( U S F S )

- a d m i n i s t e r e d f o r e s t r o a d s c o u l d b e

i n t e r p r e t e d a s i n v a l u a b l e ( U S D A F o r e s t S e r v i c e 2 0 0 9 )

. N e g a t i v e i m p a c t s o f t h e s e r o a d s

,

however, are extensive. These impacts encompass biological effects as well as hydrologic

and geomorphic changes

.

T o m i n i m i z e negative road impacts

, m a n a g e r s f r e q u e n t l y i m p l e m e n t B e s t

M a n a g e m e n t P r a c t i c e s ( B M P s )

. I n p r a c t i c e

, p h y s i c a l B M P s ( e

. g

. d r a i n d i p s

, c r o s s

-

draining culverts, rip rap) are installed based on professional judgment in the field. Often,

n o d a t a o n s e d i m e n t l e a v i n g t h e r o a d s u r f a c e o r s e d i m e n t l e a v i n g t h e b u f f e r

- thereby

e n t e r i n g a s t r e a m

- i s u s e d t o g u i d e j u d g m e n t

. O n e w a y t o address t h i s i s s u e i s t o a p p l y

s o m e f o r m o f r o a d e r o s i o n prediction model

. T h e s e m o d e l s r a n g e f r o m r e l a t i v e l y s i m p l e

,

t w o o r t h r e e v a r i a b l e e m p i r i c a l l y

- b a s e d p r e d i c t i o n e q u a t i o n s ( s u c h a s t h o s e reported by

M e g a h a n a n d K e t c h e s o n (1996)) t o c o m p l i c a t e d

, p r o c e s s

- b a s e d c o m p u t e r m o d e l s s u c h a s

W E P P : R o a d ( E l l i o t e t a l

. 1 9 9 9 )

. B y a p p l y i n g s o m e f o r m o f e r o s i o n p r e d i c t i o n m o d e l t o

road segments, managers can identify erosion hot spots and prioritize treatment

.

While a p p l y i n g h y d r o l o g y model s to r o a d s e g m e n t s p r o v i d e s i n s i g h t i n t o w h e r e

t r e a t m e n t i s m o s t c r i t i c a l

, t h e s e m o d e l s d o n o t p r o v i d e a n y h e l p i n d e t e r m i n i n g w h a t

t r e a t m e n t i s m o s t effective

. I n a d d i t i o n

, g i v e n b u d g e t c o n s t r a i n t s

, m a n a g e r s m u s t decide

w h a t B M P s a r e m o s t cost

- effective t o i n s t a l l r i g h t n o w a n d w h a t BMP s can b e i n s t a l l e d

on o t h e r s i t e s i n t h e f u ture

. E x i s t i n g B M P s m u s t b e m a i n t a i n e d t o e n s u r e c o n t i n u e d2 effectiveness ; o t h e r w i s e c a t a s t r o p h i c r o a d f a i l u r e c o u l d r e s u l t

. F u r t h e r challenges stem

f r o m t h e l o g i s t i c s a s s o c i a t e d w i t h p r o j e c t p l a n n i n g f o r B M P i n s t a l l a t i o n

, since it is

c h e a p e r t o i n s t a l l a n d m a i n t a i n B M P s i n n e a r p r o x i m i t y i n t h e s a m e t i m e p e r i o d

. A t a

s m a l l s c a l e

, t h e s e i s s u e s a r e t r a c t a b l e

. P l a n n i n g B M P s f o r l a r g e w a t e r s h e d s

, h o w e v e r

,

w h i l e t a k i n g i n t o a c c o u n t a l l p o s s i b l e t r e a t m e n t o p t i o n s a n d m a n a g e m e n t c o n s i d e r a t i o n s

,

becomes exceedingly difficult.

H e u r i s t i c o p t i m i z a t i o n p r o v i d e s a s t a r t i n g p o i n t f r o m w h i c h t h e s e p r o b l e m s c a n b e

a d d r e s s e d

. H e u r i s t i c o p t i m i z a t i o n

, i n s o l v i n g a n o b j e c t i v e f u n c t i o n w h i l e t a k i n g i n t o

a c c o u n t n u m e r o u s s i d e c o n s t r a i n t s

, a l l o w s c o m p l i c a t e d p l a n n i n g p r o b l e m s t o b e s o l v e d

o v e r r e l a t i v e l y s h o r t c o m p u t a t i o n t i m e

. A v a r i e t y o f heuristic o p t i m i z a t i o n t e c h n i q u e s

h a v e b e e n a p p l i e d t o f o r e s t p l a n n i n g i s s u e s f o r s e v e r a l d e c a d e s

, b u t h a v e o n l y m o r e

recently been incorporating environmental con straints (Weintraub et al. 2000 ).

P r e s e n t e d i n t h i s t h e s i s i s a m e t h o d o l o g y t h a t c o m b i n e s r o a d e r o s i o n m o d e l i n g w i t h

h e u r i s t i c o p t i m i z a t i o n w i t h t h e i n t e n t o f i m p r o v i n g w a t e r s h e d

- s c a l e r o a d B M P p l a n n i n g

.

S i n c e t h e s t u d y s i t e f o r d e m o n s t r a t i n g t h i s m e t h o d o l o g y w a s i n t h e L a k e T a h o e B a s i n

,

l i t e r a t u r e r e f e r e n c e s a n d p r o c e d u r e s u s e d herein c a t e r t o t h o s e c o n d i t i o n s f o u n d i n t h e

L a k e T a h o e B a s i n

. N o t e

, h o w e v e r

, t h a t t h e g e n e r a l c o n c e p t c a n b e a p p l i e d t o a n y

watershed.

T h e f o l l o w i n g section i s a l i t e r a t u r e r e v i e w o f r o a d p r i s m a n d a d j a c e n t h i l l s l o p e

hydrol o g y

, e r o s i o n m o d e l i n g

, r o a d B M P i m p l e m e n t a t i o n

, a n d o p t i m i z a t i o n t e c h n i q u e s

.

F o l l o w i n g t h e l i t e r a t u r e r e v i e w i s a m a n u s c r i p t p r e s e n t i n g a W E P P : R o a d s e n s i t i v i t y

analysis. T h e f i n a l s e c t i o n o f t h i s t h e s i s

, a l s o a manuscript, p r e s e n t s m o d e l r e s u l t s f o r

W E P P : R o a d e r o s i o n m o d e l i n g c o m b i n e d w i t h s i m u l a t e d a n n e a l i n g o p t i m i z a t i o n

.3 S i m u l a t e d a n n e a l i n g o p t i m i z a t i o n

, t h r o u g h i t e r a t i v e c o m p a r i s o n o f n e i g h b o r h o o d

s o l u t i o n s

, w a s used here to f i n d a n e a r

- o p t i m u m B M P i m p l e m e n t a t i o n a n d m a i n t e n a n c e

scenario w h i l e a c c o u n t i n g f o r m u l t i p l e c o n s t r a i n t s (fo r a c o m p l e t e d e s c r i p t i o n o f

s i m u l a t e d a n n e a l i n g

, s e e C h a p t e r 1

. 2 e )

. W i t h t h i s r e s e a r c h

, I d e m o n s t r a t e t h a t c o m b i n i n g

r o a d e r o s i o n p r e d i c t i o n m o d e l i n g w i t h h e u r i s t i c o p t i m i z a t i o n t e c h n i q u e s c a n i m p r o v e

road BMP planning and implementation over a planning ho rizon.

1.2 Literature Review

1.2a Effects of Road Construction

F o r e s t r o a d s ( h e r e a f t e r r e f e r r e d t o a s “ r o a d s ” ) c a n b e d e f i n e d a s a s u b s e t o f r o a d s

t h a t “ a r e c h a r a c t e r i z e d a s b e i n g n a r r o w

, n o t c o v e r e d w i t h a s p h a l t

, l i g h t l y t r a v e l e d

, a n d

r e m o t e ( F o r m a n a n d Alexander 1998).” While m o r e p r i m i t i v e a n d d e s i g n e d t o access

r o u g h e r t e r r a i n t h a n o t h e r r o a d s ( F o r m a n a n d A l e x a n d e r 1 9 9 8 )

, t h e s e r o a d s m u s t a l s o

a c c o m m o d a t e l a r g e r v e h i c l e s t o f a c i l i t a t e a c t i v i t i e s s u c h a s t i m b e r h a r v e s t

, r e c r e a t i o n

,

g r a z i n g

, a n d m i n i n g ( A k a y e t a l

. 2 0 0 5

, S w i t a l s k i e t a l

. , 2 0 0 3

, F o r m a n

, 2 0 0 0 )

. W h i l e

F o r m a n a n d A l e x a n d e r ’ s d e f i n i t i o n e x c l u d e s a s p h a l t s u r f a c e d r o a d s

, t h e d e f i n i t i o n u s e d

t h r o u g h t h e c o u r s e o f t h i s t h e s i s w i l l i n c l u d e p a v e d r o a d s e g m e n t s

, s i n c e t h e L a k e T a h o e

B a s i n p r o v i d e s a n o t a b l e e x c e p t i o n t o t h i s d e f i n i t i o n b y u s i n g a s p h a l t p a v i n g o n i t s r o a d

network.

The e f f e c t s o f r o a d e r o s i o n b e g i n w i t h t h e f i r s t g r o u n d b r e a k i n g f o r a r o a d b e d

.

Vegetation is removed from the future road bed, exposing soil to greater raindrop impact.

Nut rient

- r i c h t o p s o i l i s a l s o r e m o v e d

, c r e a t i n g a p o s i t i v e f e e d b a c k l o o p t h a t l e a d s t o l e s s

plant regeneration and greater exposure of organic matter

- deficient soils to erosive forces.4 S o i l c o m p a c t i o n a g g r e g a t e s t h e s o i l ’ s s u s c e p t i b i l i t y t o e r o s i o n ( G r i s m e r a n d H o g a n 2004,

Switalski et al. 2004).

R o a d s c r o s s c u t t i n g h i l l s l o p e s r e r o u t e g r o u n d w a t e r t o t h e s u r f a c e t h r o u g h t h e r o a d ’ s

c u t s l o p e

, c a u s i n g a n i n c r e a s e i n o v e r l a n d f l o w ( L u c e 2 0 0 2 )

. W i t h i n c r e a s e s i n r o a d

d e n s i t y ( n u m b e r o f r o a d s p e r u n i t a r e a ) c o m e i n c r e a s e s i n d r a i n a g e d e n s i t y

, s i n c e r o a d s

c a n b e c o m e d r a i n a g e p a t h s t h e m s e l v e s ( W e m p l e e t a l

. 1996). R o a d s t e n d t o i n c r e a s e t h e

a m o u n t o f r u n o f f d e l i v e r e d t o s t r e a m s a n d a l s o i n c r e a s e in

- s t r e a m e r o s i o n ( J o n e s e t a l

.

2000, Maholland 2002). As a result, frequency and magnitude of sm all stream peak flows

increases (Maholland 2002, Luce 2002).

R o a d s b e c o m e a c h r o n i c f i n e s o u r c e o f s e d i m e n t i n a w a t e r s h e d ( L u c e 2 0 0 2 ) a n d

c a n g r e a t l y i n c r e a s e t h e p o t e n t i a l f o r l a n d s l i d e s a n d m a s s f l o w s i n f o r e s t e d w a t e r s h e d s

( G r i g a l 2 0 0 0

, J o n e s e t a l

. 2 0 0 0 )

, a t t i m e s t o s u c h a n e x t e n t t h a t m a s s f l o w b e c o m e s t h e

predominant sediment source for streams (Megahan and Hornbeck 2000).

C u l v e r t s a r e p o t e n t i a l l y r e s p o n s i b l e f o r s e v e r a l o f t h e h y d r o l o g i c

, g e o m o r p h i c

, a n d

b i o l o g i c a l c o n s e q u e n c e s o f r o a d s

. I f i m p r o p e r l y s i z e d

, c u l v e r t s w i l l i n c r e a s e w a t e r s p e e d

a n d s u b s e q u e n t e r o s i v e p o t e n t i a l o f r u n o f f ( M a h o l l a n d 2 0 0 2 )

. W i t h t h i s i n c r e a s e i n

e r o s i v e p o t e n t i a l

, n e w c h a n n e l s m a y f o r m a s a r e s u l t o f c u l v e r t p l a c e m e n t a n d

p e r m a n e n t l y a l t e r s t r e a m n e t w o r k s t r u c t u r e ( W e m p l e e t a l

. 1 9 9 6 )

. I n a d d i t i o n

, culverts

h a v e b e e n f o u n d t o b e e n t r y p o i n t s f o r s e d i m e n t a n d o t h e r s t r e a m p o l l u t a n t s ( F o r m a n a n d

Alexander 1 9 9 8 )

. I m p r o p e r l y p l a c e d c u l v e r t s c a n b e c o m e p l u g g e d

, r e r o u t i n g w a t e r t o

other stream cha nnels or directly down the road, and potentially causing washouts, severe

g u l l y e r o s i o n

, o r p o t e n t i a l l y e v e n l a n d s l i d e s w h e n t h e d r a i n a g e s y s t e m b e c o m e s5 c o m p l e t e l y o v e r w h e l m e d ( F o r e s t P r a c t i c e s A d v i s o r y C o m m i t t e e ( F P A C 2 0 0 0 ) )

. C u l v e r t s

may serve as an impe diment to upstream fish passage (FPAC 2000).

B e y o n d f i s h p a s s a g e i s s u e s

, o t h e r b i o l o g i c a l i m p a c t s a r e a l s o o f c o n c e r n w h e n

d i s c u s s i n g r o a d s a n d t h e i r e f f e c t s o n t h e l a n d s c a p e

. R o a d s c r e a t e a m e d i u m f o r

introduction o f i n v a s i v e p l a n t s p e c i e s ( F P A C 2 0 0 0

, S w i t a l s k i e t a l

. 2 0 0 4 )

. C h r o n i c i n p u t s

o f f i n e s e d i m e n t t e n d t o c a u s e i n c r e a s e d s t r e a m t u r b i d i t y

, w h i c h c a n c a u s e p r o b l e m s f o r

f i s h

, a q u a t i c v e g e t a t i o n

, a n d m a c r o

- inve r t e b r a t e s ( F o r m a n a n d A l e x a n d e r 1 9 9 8 )

. R o a d s

,

especially at c u l v e r t s

, c a n b l o c k m o v e m e n t o f l a r g e w o o d p i e c e s d o w n h i l l

, w h i c h a r e

i m p o r t a n t f o r s t r e a m h a b i t a t

. A b u i l d u p o f w o o d a n d d e b r i s a b o v e a c u l v e r t c o u l d

e v e n t u a l l y r e s u l t i n a c u l v e r t b l o w o u t a n d d e b r i s f l o w d o w n h i l l ( F P A C 2 0 0 0 )

. I n t e r m s o f

w i l d l i f e

, r o a d s d i s r u p t c o n t i g u o u s h a b i t a t s e c t i o n s a n d c r e a t e b a r r i e r s t o m o v e m e n t a n d

m i g r a t i o n ( F o r m a n a n d D e b l i n g e r 2 0 0 0 )

. N o i s e p o l l u t i o n i s a l s o a n i s s u e

, c a u s i n g m o r e

problems for some species than others (Forman and Alexander 1998).

1 .2 b Factors Affecting Severity of Road Impacts

P a r e n t m a t e r i a l s a n d s o i l t y p e i n f l u e n c e r o a d e r o s i o n p o t e n t i a l

. S u g d e n a n d W o o d s

( 2 0 0 7 ) f o u n d t h a t t h e a v e r a g e a n n u a l s e d i m e n t y i e l d f r o m B e l t M e t a s e d i m e n t s i s s i m i l a r

t o t h e a m o u n t o f e r o s i o n f o u n d i n b a s a l t

, s a n d s t o n e

, a n d o t h e r s e d i m e n t a r y m a t e r i a l s i n

t h e N o r t h w e s t U n i t e d S t a t e s

, b u t f a r l e s s t h a n f o r g r a n i t i c p a r e n t m a t e r i a l s l i k e t h o s e

t e s t e d i n t h e I d a h o B a t h o l i t h b y o t h e r r e s e a r c h e r s

. R e s e a r c h i n t h e L a k e T a h o e B a s i n h a s

s h o w n v o l c a n i c p a r e n t m a t e r i a l s t o b e e v e n m o r e e r o d i b l e t h a n the g r a n i t i c p a r e n t

materials that also dominate the basin ’s lithology (Grismer and Hogan 2005a). Glacial till

p a r e n t m a t e r i a l s a r e s i m i l a r i n s e d i m e n t c o n t r i b u t i o n t o t h e B e l t S u p e r g r o u p s t u d i e d b y6 S u g d e n a n d W o o d s ( 2 0 0 7 )

. I n g e n e r a l

, f i n e r s o i l s t e n d t o c o n t r i b u t e m o r e s e d i m e n t f o r

runoff than coarser

- textured soils (Luc e and Black 1999, Grismer and Hogan 2005a).

P h y s i c a l l o c a t i o n a n d c o n s t r u c t i o n o f a r o a d a l s o p l a y s a r o l e i n a r o a d ’ s

susceptibility t o e r o s i o n

. P a c k e r ( 1 9 6 7 ) f o u n d t h a t t h e d i s t a n c e t o t h e c l o s e s t o b s t r u c t i o n

below t h e r o a d p r i s m i s d i r e c t l y r e l a t e d t o h o w m u c h s e d i m e n t r e a c h e s a s t r e a m c h a n n e l

f r o m t h e r o a d

. G r e a t e r d i s t a n c e b e t w e e n r o a d s a n d s t r e a m s m e a n s

, i n a l l l i k e l i h o o d

, m o r e

o b s t r u c t i o n s

, a n d t h e r e f o r e l e s s s e d i m e n t d e l i v e r e d

. T h i s f a c t

, h o w e v e r

, i s a l s o c o n t ingent

upon the degree of hydrologic connectivity to th e stream network (Wemple et al. 1996).

P r e s e n c e o r a b s e n c e o f a g g r e g a t e s u r f a c i n g

, d e p t h o f t h a t s u r f a c i n g

, a n d q u a l i t y o f

t h a t s u r f a c i n g c a n a f f e c t r o a d e r o s i o n r a t e s ( S w i f t 1 9 8 4

, F o l t z a n d T r u e b e 2 0 0 3 )

. S t e e p e r

s l o p e s a n d l o n g e r r o a d s e g m e n t s w i l l i n c r e a s e r o a d e r o s i o n r a t e s ( S u g d e n a n d W o o d s

2007, L u c e a n d B l a c k 1 9 9 9 )

. A s p e c t o f s l o p e w i l l i n f l u e n c e a v a i l a b l e w a t e r

, a n d a s a

r e s u l t w i l l a l s o c o n t r o l p o t e n t i a l s u r f a c e e r o s i o n ( P a c k e r 1 9 6 7 )

. I n a d d i t i o n

, r o a d

g e o m e t r y ( i n s l o p e d v e r s u s o u t s l o p e d o r c r o w n e d r o a d p r o f i l e

, r o a d w i d t h ) w i l l a l s o s e r v e

a s a c o n t r o l o n s e d i m e n t p r o d u c t i o n ( L u c e a n d B l a c k 1 9 9 9

, P a c k e r 1 9 6 7 )

. L o c a t i o n o f

s e d i m e n t o r i g i n o n t h e r o a d p r i s m p a r t i a l l y r e g u l a t e s roa d s e d i m e n t t r a v e l d i s t a n c e

(Megahan and Hornbeck 2000).

C u t s l o p e h e i g h t a n d a n g l e w i l l v a r y s e d i m e n t y i e l d

, a s w i l l p r e s e n c e o r a b s e n c e o f

v e g e t a t i o n o n t h e c u t s l o p e

, i n t h e d i t c h

, a n d o n t h e r o a d ’ s f i l l s l o p e ( L u c e a n d B l a c k

1 9 9 9 )

. T h e a m o u n t o f c u t s l o p e r u n o f f c o n t r i b u t i o n r e l a t i v e t o t h e r o a d b e d i t s e l f i s n o t

g e n e r a l l y a g r e e d u p o n b y r e s e a r c h e r s ( L u c e 2002 )

. C u t s l o p e i n t e r c e p t i o n o f s u b s u r f a c e

f l o w a n d t h e c o n s e q u e n t c o n t r i b u t i o n o f s u b s u r f a c e f l o w t o r o a d r u n o f f a n d s u r f a c e

e r o s i o n m a y b e a m a j o r c o n t r i b u t o r t o r o a d s u r f a c e e r o s i o n i n w e t t e r c l i m a t e s a n d7 l a n d s c a p e s ( W e m p l e a n d J o n e s 2 0 0 3

, L u c e 2002 )

. S l o p e l e n g t h

, s o i l d e p t h

, s u b s u r f a c e

t o p o g r a p h y

, a n d c u t s l o p e h e i g h t r e l a t i v e t o t o t a l d e p t h o f c u t s l o p e t o b e d r o c k a l l d i c t a t e

degree of groundwater inte rception and surface runoff (Wemple and Jones 2003).

R o a d l o c a t i o n o n a s l o p e c a n p l a y a n i m p o r t a n t r o l e i n d e t e r m i n i n g e r o s i o n

potential. R o a d s l o c a t e d h i g h o n a s l o p e a r e m o r e s u s c e p t i b l e t o e r o s i o n a s a r e s u l t o f

r e c e i v i n g a g r e a t e r a m o u n t o f p r e c i p i t a t i o n d u e t o o r o g r a p h i c e f f e c t ( M a h o l l a n d 2 0 0 2 )

.

R o a d s h i g h o n a s l o p e

, h o w e v e r

, t e n d t o b e m i n i m a l l y c o n n e c t e d t o s t r e a m s ( d u e t o

m i n i m a l s t r e a m c h a n n e l f o r m a t i o n ) a n d t h e r e f o r e h a v e a l o w e r p r o p o r t i o n a l i m p a c t o n

s t r e a m s e d i m e n t a t i o n ( J o n e s e t a l

. 2 0 0 0

, B l o o m 1 9 9 8 )

. R o a d s

, h o w e v e r

, c a n c o n c e n t r a t e

f l o w

, c r e a t i n g c h a n n e l s h i g h e r o n t h e s l o p e t h a n i f n o r o a d s w e r e p r e s e n t ( F o r m a n a n d

A l e x a n d e r

, 1 9 9 8 )

. R o a d s l o c a t e d o n t h e m i d

- a n d l o w

- s l o p e c a n b e m a j o r c o n t r i b u t o r s o f

s e d i m e n t t o s t r e a m c h a n n e l s ( M a h o l l a n d 2 0 0 2

, B l o o m 1 9 9 8 )

. I n w e s t e r n O r e g o n

, m id

-

s l o p e r o a d s t e n d t o b e n e t s o u r c e s o f s e d i m e n t

, w h e r e a s v a l l e y f l o o r r o a d s t e n d t o b e n e t

sinks (Jones et al. 2000).

N e w r o a d s t e n d t o p r o d u c e m o r e s e d i m e n t t h a n o l d r o a d s

, a n d n e w l y d i s t u r b e d

r o a d s ( f o r e x a m p l e

, r o a d s t h a t h a v e b e e n r e c e n t l y g r a d e d ) p r o d u c e m o r e s e d i m e n t t h a n

undisturbed roads (Megahan and Kidd 1972, Swift 1984, Grigal 2000).

T r a f f i c o n f o r e s t r o a d s i s a d o m i n a t i n g f a c t o r i n t h e a m o u n t o f s e d i m e n t p r o d u c e d

( R e i d a n d D u n n e 1984)

. R u t s

, b y c h a n n e l i n g r u n o f f d i r e c t l y d o w n t h e r o a d g r a d e

,

i n c r e a s e e r o s i o n p o t e n t i a l ( S w i f t 1 9 8 4

, G r i g a l 2 0 0 0 )

. W i t h t h e s e f a c t o r s i n m i n d

, r o a d

maintenance regimen will influence road erosion potential ( Swift 1984).

C l i m a t e p l a y s a m a j o r r o l e i n c o n t r o l ling r o a d e r o s i o n p o t e n t i a l

. R a i n f a l l i n t e n s i t y

a n d d u r a t i o n affect s u r f a c e e r o s i o n ( G r i g a l 2 0 0 0 )

. I n a r e a s w h e r e s n o w m e l t i s n o t t h e8 d o m i n a n t f o r m o f p r e c i p i t a t i o n

, s n o w m e l t r u n o f f m a y n o t e x c e e d f o r e s t s o i l i n f i l t r a t i o n

r a t e s o r s o i l c r i t i c a l s h e a r s t r e s s v a l u e s

, m a k i n g i t a m i n o r contributor t o s e d i m e n t a t i o n

( E l l i o t 2 0 0 6 )

. I n c o n t r a s t

, t h e m a j o r i t y o f s e d i m e n t r e a c h i n g d o w n s t r e a m w a t e r b o d i e s

from u p l a n d s o u r c e s m a y c o m e d u r i n g s p r i n g s n o w m e l t i n e n v i r o n m e n t s w h e r e s n o w i s

the dominant form of precipitation (Simon et al . 2006).

A d j a c e n t f o r e s t m a n a g e m e n t p r a c t i c e s c a n a f f e c t s e d i m e n t p r o d u c t i o n f r o m r o a d s

.

F e w e r t r e e s a d j a c e n t t o a g i v e n r o a d s e c t i o n w i l l p r o d u c e m o r e w a t e r y i e l d t h a n a t h i c k e r

f o r e s t s t a n d a n d c o n s e q u e n t l y s h e d m o r e w a t e r t o t h e r o a d g r a d e ( L u c e a n d B l a ck 1999,

M e g a h a n a n d H o r n b e c k 2 0 0 0

, G r i g a l 2 0 0 0 )

. I n m o s t c a s e s

, s e d i m e n t p r o d u c t i o n f r o m

r o a d s h a s b e e n f o u n d t o g r e a t l y e x c e e d t h e a m o u n t o f s e d i m e n t p r o d u c e d b y t h e t i m b e r

harvest for which they were built to access (Megahan and Kidd 1972, Sugden and Wo ods

2007).

W i t h a l l o f t h e s e f a c t o r s t a k e n i n t o c o n s i d e r a t i o n

, i t i s c l e a r t h a t t r a n s p o r t a t i o n

n e t w o r k p l a n n i n g p l a y s a c r u c i a l r o l e i n h o w m u c h s e d i m e n t i s p r o d u c e d b y f o r e s t r o a d

networks (Krogstad and Schiess 2000, FPAC 2000).

1.2c Mitigation o f Road Impacts Using Best Management Practices

T o a d d r e s s a n d m i n i m i z e e f f e c t s o f r o a d e r o s i o n

, s c i e n t i s t s a n d m a n a g e r s h a v e

f o r m u l a t e d s t a n d a r d s

, o r B e s t M a n a g e m e n t P r a c t i c e s ( B M P s )

, a s g u i d e l i n e s f o r h o w

p r o j e c t s s h o u l d b e c o n d u c t e d a n d c o n s t r u c t e d

. “ B e s t M a n a g e m e n t P r a c t i c e s or ‘ BMPs ’

a r e t h o s e p r i n c i p a l s a n d e n g i n e e r i n g d e s i g n p r a c t i c e s t h a t w i l l p r o t e c t w a t e r q u a l i t y a s

well as the function of the road when prop erly applied (Keller and Sherar 2007).” Besides

roads, BMPs practices have also been formulated for a number of landscape management9 p r a c t i c e s

, f o r e x a m p l e a g r i c u l t u r e ( B r o w n e t a l

. 200 7 )

, h a z a r d f u e l r e d u c t i o n ( O’Connell

2006 ), grazing (Wyoming Depa rtment of Environmental Quality 1997), and mining (U.S.

EPA 2000).

R o a d B M P s c a n b e s t r u c t u r a l / p h y s i c a l o r p l a n n i n g i n n a t u r e

. E x a m p l e s o f

s t r u c t u r a l / p h y s i c a l r o a d B M P s i n c l u d e c u l v e r t s

, d r a i n d i p s o r w a t e r b a r s

, a n d resurfacing.

P l a n n i n g B M P e x a m p l e s i n c l u d e m a i n t e n a n c e f r e q u e n c y o r l i m i t i n g w h a t l e n g t h o f r o a d

surface can be graded at one time ( USDA Forest Service 2000).

P h y s i c a l B M P s u s e d i n t h e L a k e T a h o e B a s i n : S i n c e L a k e T a h o e i s a u n i q u e

m a n a g e m e n t s i t u a t i o n ( s p a n n i n g t w o s t a t e s

, m u l t i p l e n a t i o n a l f o r e s t s

, a n d b e i n g

s u s c e p t i b l e t o h e a v y u s e r t r a f f i c )

, t h e L a k e T a h o e B a s i n h a s i t s o w n USFS management

district

- t h e L a k e T a h o e B a s i n M a n a g e m e n t U n i t ( L T B M U )

- a l o n g w i t h a n u m b e r o f

o t h e r p l a n n i n g a g e n c i e s

. T o e n s u r e c o m p l i a n c e w i t h i t s B M P s

, t h e L T B M U h a s i n i t i a t e d

a n a n n u a l m o n i t o r i n g p r o g r a m t o e v a l u a t e e f f e c t i v e n e s s o f m a n d a t e d B M P s

. I n g e n e r a l

,

L T B M U B M P s h a v e b e e n e f f e c t i v e a c c o r d i n g t o t h e i r e v a l u a t i o n c r i t e r i a ( B r i l l e t a l

.

2009, Heller and Norman 2005).

S t r u c t u r a l / p h y s i c a l B M P s u s e d f r e q u e n t l y i n t h e L a k e T a h o e B a s i n i n c l u d e ( b u t a r e

n o t l i m i t e d t o ) c u l v e r t s

, g r a v e l

, n a t i v e a n d r o c k e d d i t c h e s

, r i p r a p

, d r a i n d i p s

, a n d

pavement. Discussions pertinent to those BMPs assigned to problem road segments in the

Lake Tahoe Basin study watershed are below (f or further detail, see Chapter s 2 and 3 )

.

Pavement: I n t e r m s o f s u r f a c i n g

, p a v i n g r o a d s w i l l p r e v e n t s e d i m e n t e n t r a i n m e n t

f r o m t h e r o a d b e d

, b u t i n t u r n w i l l c r e a t e a n i m p e r v i o u s s u r f a c e t h a t m a y c o n c e n t r a t e

w a t e r a n d s e d i m e n t i n t o d r a i n a g e s t r u c t u r e s ( M a h o l l a n d 2 0 0 2 )

. N o n e t h e l e s s

, p a v i n g m a y10 b e t h e b e s t s e d i m e n t m i t i g a t i o n s o l u t i o n f o r h i g h

- t r a f f i c r o a d s ( Re i d a n d D u n n e 1 9 8 4

,

C l i n t o n a n d V o s e 2 0 0 4 )

. P a v i n g s h o r t r o a d s e g m e n t s i n m o u n t a i n o u s t e r r a i n i s a c o s t l y

endeavor (USDA Forest Service 2008), and as such is used relatively infrequently.

D r a i n d i p s : D r a i n d i p s f a l l i n t o t h e b r o a d c a t e g o r y o f s u r f a c e c r o s s drains. By

interrupting h y d r a u l i c a l l y c o n t i g u o u s s e c t i o n s o f r o a d

, s e g m e n t l e n g t h

, w h i c h h a s b e e n

f o u n d t o b e a n i m p o r t a n t v a r i a b l e i n d e t e r m i n i n g s e d i m e n t p r o d u c t i o n o n f o r e s t r o a d s

( e

. g

. L u c e a n d B l a c k 2 0 0 1 a

, C o e 2 0 0 6 )

, i s m i n i m i z e d

. B e y o n d s e g m e n t l e n g t h,

a ppropriate d r a i n d i p s p a c i n g i s d i c t a t e d b y a n u m b e r o f d i f f e r e n t f a c t o r s

, i n c l u d i n g

(among others) surfacing material charac teristics, climate, and road grade (Copstead et al.

1998)

.

Outsloping : U n d e r t h i s r o a d p r o f i l e d e s i g n

, r u n o f f i s n o t c o n c e n t r a t e d i n t o a p o i n t

s o u r c e ; r a t h e r

, r u n o f f i s d i s p e r s e d o f f t h e s h o u l d e r a l o n g t h e e n t i r e l e n g t h o f t h e r o a d

segment. B y d i s p e r s i n g r u n o f f a n d s e d i m e n t i n t h i s f a s h i o n

, s e d i m e n t i s l e s s l i k e l y t o

r e a c h a s t r e a m ( L u c e a n d B l a c k 2 0 0 1 a

, E l l i o t e t a l

. 2 0 0 9 ). W h i l e a h i g h l y e f f e c t i v e B M P

,

o u t s l o p i n g i s n o t a p p r o p r i a t e i n a l l s i t u a t i o n s ( s u c h a s o n w e t o r s t e e p r o a d s w i t h h e a v y

t r u c k t r a f f i c ) a n d r e q u i r e s m o r e i n t e n s i v e m a i n t e n a n c e t h a n o t h e r B M P s ( U S D A F o r e s t

Service 2008)

.

R o a d d e c o m m i s s i o n i n g : I f a r o a d s e g m e n t i s u n n e c e s s a r y

, i t c a n b e p e r m a n e n t l y

r e m o v e d f r o m t h e r o a d n e t w o r k ( S w i t a l s k i e t a l 2 0 0 4 )

. R o a d d e c o m p a c t i o n a n d p r i s m

r e s t o r a t i o n a r e b e c o m i n g m o r e p o p u l a r o p t i o n s f o l l o w i n g d e c o m m i s s i o n i n g ( L u c e 2 0 0 2

,

S w i t a l s k i e t a l

. 2 0 0 4 )

. T h e L a k e T a h o e B a s i n r e c e n t l y f i n i s h e d a p e r i o d o f e x t e n s i v e

f o r e s t r o a d d e c o m m i s s i o n i n g

, a n d a s s u c h i s n o l o n g e r w i d e l y a p p l y i n g t h i s B M P ( P

.

Potts personal communication).11 1.2d Road Erosion Prediction Using Models

G e n e r a l o v e r v i e w o f h y d r o l o g i c m o d e l s : T o a s s e s s r u n o f f a n d e r o s i o n

, r e s e a r c h e r s

a n d m a n a g e r s h a v e e n l i s t e d t h e h e l p o f m a t h e m a t i c a l h y d r o l o g i c m o d e l s f o r m a n y y e a r s

(Sorooshian et al. 2008 , Loague and VanDerKwaak 2004 )

. These models fall into several

b r o a d c a t e g o r i e s : e m p i r i c a l v e r s u s p r o c e s s ( physics )

- b a s e d

, s t o c h a s t i c v e r s u s

deterministic, and lumped versus distributed.

I n u s e s i n c e t h e 1 9 7 0 ’ s

, t h e U n i v e r s a l S o i l L o s s E q u a t i o n (USLE) i s a w i d e l y u s e d

empirically

- based e r o s i o n p r e d i c t i o n m o d e l ( W i s c h m e i e r a n d S m i t h 1 9 7 8 )

. T h e R e v i s e d

U n i v e r s a l S o i l L o s s E q u a t i o n (RUSLE) a n d t h e M o d i f i e d Universal S o i l L o s s E q u a t i o n

(MUSLE) a r e t w o m o r e r e c e n t i m p r o v e m e n t s o n t h e o r i g i n a l m o d e l ( B r o o k s e t a l

. 2003).

E m p i r i c a l m o d e l s d o n o t m a k e f u l l u s e o f o u r u n d e r s t a n d i n g o f h y d r o l o g i c s y s t e m

dynamics

. P rocess

- b a s e d m o d e l s

, i n c o n t r a s t

, i n c o r p o r a t e k n o w l e d g e a b o u t t h e p h y s i c s o f

a s y s t e m t o d e r i v e m o r e detailed yet generalizable predict ions o f r u n o f f a n d s e d i m e n t

( Renschler 2003 ).

A s a s u b

- c a t e g o r y o f p rocess

- b a s e d m o d e l s

, s t o c h a s t i c m o d e l s d r a w v a r i a b l e i n p u t s

f r o m p r o b a b i l i t y d i s t r i b u t i o n s

. I n c o n t r a s t

, d e t e r m i n i s t i c m o d e l s d e f i n e i n p u t v a r i a b l e s a s

b e i n g f r e e f r o m r a n d o m v a r i a t i o n ( L o a g u e a n d V a n D e r K w a a k 2004)

. A f u r t h e r

s u b d i v i s i o n w i t h i n h y d r o l o g i c m o d e l s s t e m s f r o m w h e t h e r t h e m o d e l t r e a t s s p a t i a l

w a t e r s h e d v a r i a b i l i t y i n a l u m p e d v e r s u s d i s t r i b u t e d f a s h i o n

. W h i l e d i s t r i b u t e d m o d e l s

a l l o w f o r s p a t i a l v a r i a b i l i t y i n c l i m a t e a n d h y d r o l o g i c p r o c e s s e s a c r o s s a w a t e r s h e d

,

l u m p e d m o d e l s d o n o t

. A c c o u n t i n g f o r s p a t i a l v a r i a b i l i t y p r o d u c e s a m o r e a c c u r a t e

r e p r e s e n t a t i o n o f w a t e r s h e d

- s c a l e h y d r o l o g i c p r o c e s s e s

. A s a t r a d e o f f

, t h e s e m o d e l s c a n12 b e h i g h l y c o m p l e x a s a r e s u l t o f requiring d e t a i l e d s p a t i a l l y

- e x p l i c i t d a t a and may

demand greater computation resources (Sorooshian et a l. 2008).

D i s t r i b u t e d H y d r o l o g y

- Soil

- Vegetation M o d e l ( D H S V M ) ( W i g m o s t a e t a l

. 1994),

and Syst è me Hydrologique Europ é en Sediment Yield Component ( SHESED ) (Wicks and

Bathurst 1 9 9 6 ) a r e e x a m p l e s o f fully process

- b a s e d m o d e l s c u r r e n t l y i n u s e

. T h e W a t e r

E r o s i o n P r e d i c t i o n P r o j e c t ( W E P P ) ( F l a n a g a n a n d N e a r i n g 1995)

, a l s o a f u l l y p r o c e s s

-

b a s e d h y d r o l o g i c m o d e l

, h a s o v e r 4 0 0 i n p u t p a r a m e t e r s

. O r i g i n a l l y d e s i g n e d f o r

a g r i c u l t u r e

, i t h a s b e e n a d a p t e d f o r u s e i n f o r e s t c o n d i t i o n s ( E l l i o t e t a l

. 2 0 0 6 ) a n d h a s

be e n a p p l i e d t o a v a r i e t y o f w a t e r s h e d s w i t h s u c c e s s a t a v a r i e t y o f s c a l e s ( A m o r e e t a l

.

2004).

H y d r o l o g i c m o d e l i n g a n d r o a d e r o s i o n : E m p i r i c a l a n d p rocess

- b a s e d m o d e l s a l i k e

h a v e b e e n d e v e l o p e d t o predict r o a d e r o s i o n

. S e v e r a l s t u d i e s h a v e d e v e l o p e d road

s e d i m e n t v o l u m e a n d t r a v e l p r e d i c t i o n e q u a t i o n s f r o m e m p i r i c a l d a t a ( e

. g

. M e g a h a n a n d

K e t c h e s o n 1 9 9 6

, A n d e r s o n a n d M a c D o n a l d 1 9 9 8 )

. T h e s e e m p i r i c a l m o d e l s a r e

c o m p u t e r i z e d i n s o m e i n s t a n c e s ; R O A D M O D a n d S T J

- E R O S

, t w o G I S

- b a s e d m o d e l s

c a p a b l e o f p r e d i c t i n g r o a d e r o s i o n

, c a l c u l a t e e r o s i o n u s i n g e m p i r i c a l r e l a t i o n s h i p s

(Ramos

- Scharron and MacDonald 2007).

A s p r o c e s s

- b a s e d h y d r o l o g i c m o d e l s h a v e b e c o m e m o r e p r e v a l e n t

, s o t o o h a v e

process

- b a s e d r o a d e r o s i o n p r e d i c t i o n t o o l s

. S W A T

, w h i l e n o t s p a t i a l l y

- explici t, is

c a p a b l e o f p r e d i c t i n g r o a d e r o s i o n ( N e i t s c h e t a l

. 2 0 0 5 ) ( D e s p i t e b e i n g generally

conside r e d a p h y s i c s

- b a s e d m o d e l

, S W A T ’ s e r o s i o n c o m p u t a t i o n s a r e b a s e d o n e m p i r i c a l13 models )

. D o t e n a n d o t h e r s ’ ( 2 0 0 6 ) m o d i f i c a t i o n o f D H S V M t o a c c o m m o d a t e r o a d

sedimen t was the fir st spatially

- explicit physics

- based model to incorporate road erosion.

W i t h p r o c e s s

- based m o d e l s h a v e c o m e c o m p l e x i t y a n d i n a c c e s s i b i l i t y t o u n t r a i n e d

u s e r s

. W E P P : R o a d

, a u s e r

- f r i e n d l y w e b

- b a s e d i n t e r f a c e f o r W E P P

, h a s b e e n d e v e l o p e d

by the Rocky Mountain Research Station (Elliot et al. 2004 ) to address this problem. This

mark s t h e f i r s t adaptation o f a process

- b a s e d m o d e l s p e c i f i c a l l y f o r predict ing sediment

f r o m r o a d s e g m e n t s

. W E P P : R o a d r e q u i r e s f e w i n p u t p a r a m e t e r s

, m a n y o f w h i c h c a n b e

a c q u i r e d w i t h o u t f i e l d s u r v e y s

. T h e i n t e r f a c e a l l o w s u s e r s f r o m a v a r i e t y o f t e c h n i c a l

b a c k g r o u n d s t o e f f e c t i v e l y p r e d i c t i m p a c t s a s s o c i a t e d w i t h r o a d

- r e l a t e d m a n a g e m e n t

d e c i s i o n s

. B y p r o v i d i n g a r a n g e o f c l i m a t e s ( a n d t h e o p t i o n t o a l t e r c l i m a t e s t o r e p r e sent

site

- s p e c i f i c c o n d i t i o n s )

, s u r f a c e t y p e s

, t r a f f i c l e v e l s

, a n d r o a d d e s i g n s

, W E P P : R o a d i s

applicable virtually anywhere in the U.S.

1.2e Natural Resource Planning and Decision Support Tools

F o r e s t a n d n a t u r a l r e s o u r c e p l a n n i n g

, e s p e c i a l l y w h e n a c coun t i n g f o r m u l t i p l e u s e s

,

has b e c o m e e v e r m o r e c o m p l e x o v e r t i m e ( R ö n n q v i s t 2 0 0 3 ). O p t i m i z a t i o n s t r a t e g i e s

( i n c l u d i n g a p p l i c a t i o n t o f o r e s t r o a d s ) h a v e b e e n e m p l o y e d s i n c e t h e 1 9 7 0 ’ s t o a d d r e s s

m u l t i p l e m a n a g e m e n t g o a l s a n d e n v i r o n m e n t a l c o n s t r a i n t s i n f o r e s t p l a n n i n g ( W e i n t r a u b

et al. 1995, Rönnqvist 2003, Weintraub 2006 ).

O p t i m i z a t i o n s t r a t e g i e s c o n s i s t o f e i t h e r e x a c t s o l u t i o n s o r h e u r i s t i c s ( K i r k p a t r i c k e t

a l

. 1 9 8 3 )

. L i n e a r p r o g r a m m i n g

, i n t e g e r p r o g r a m m i n g

, a n d m i x e d i n t e g e r p r o g r a m m i n g

a r e a l l c o m m o n e x a c t s o l u t i o n m e t h o d s

. W h i l e e x a c t s o l u t i o n s a r e o f t e n p r e f e r r e d

,

p r o b l e m c o m p l e x i t y m a y r e q u i r e e x c e s s i v e c o m p u t a t i o n p o w e r o r t i m e ( K o w a l s k i 1 9 9 5 )

.14 I n t h e s e c a s e s

, h e u r i s t i c s a r e f a v o r a b l e

. W h i l e n o t g u a r a n t e e d t o f i n d t h e e x a c t s o l u t i o n

,

h e u r i s t i c s p r o d u c e n e a r o p t i m u m s o l u t i o n s d u r i n g m u l t i p l e p r o c e s s r e p e t i t i o n s w i t h l e s s

computing time (Lin and Kernighan 1973).

W i t h i n c r e a s i n g c o n c e r n f o r e n v i r o n m e n t a l i m p a c t o f f o r e s t o p e r a t i o n s h a s c o m e

i n c o r p o r a t i o n o f i m p a c t m i t i g a t i o n s t r a t e g i e s i n t o t h e p l a n n i n g p r o c e s s ( W e i n t r a u b e t a l

.

2000 ). S e d i m e n t a t i o n a s s o c i a t e d w i t h t i m b e r h a r v e s t h a s b e e n a c c o u n t e d f o r s i n c e t h e

1 9 7 0 ’ s u s i n g l i n e a r p r o g r a m m i n g t e c h n i q u e s ( H o f a n d B e v e r s 2 0 0 2 )

. A p p l i c a t i o n o f

h e u r i s t i c o p t i m i z a t i o n s p e c i f i c a l l y t o e n v i r o n m e n t a l c o n c e r n s

, i n c l u d i n g s e d i m e n t a t i o n

a s s o c i a t e d w i t h r o a d s

, h a s o n l y o c c u r r e d m o r e r e c e n t l y ( C h u n g 2 0 0 2

, W e i n t r a u b e t a l

.

2000 ).

Optimization a n d r oad i mpact a nalysis: M u l t i p l e p r o j e c t s t o d a t e h a v e i n c o r p o r a t e d

B M P s a n d /or a s s o c i a t e d e r o s i o n p o t e n t i a l i n t o c o s t

- b e n e f i t a n a l y s e s f o r r o a d m a n a g e m e n t

p l a n n i n g

. A r u g a a n d o t h e r s (2005) optimized r o a d a l i g n m e n t s u s i n g a T a b u S e a r c h

algorith m

. T o i n c o r p o r a t e r o a d i m p a c t c o n c e r n s

, r o a d s e d i m e n t w a s a c c o u n t e d f o r with

empirically

- d e r i v e d e r o s i o n e q u a t i o n s

. BMPs a s s i g n e d t o r o a d s e g m e n t s i n c l u d e d road

s u r f a c e m a t e r i a l

, c u l v e r t l o c a t i o n ( s e g m e n t l e n g t h )

, a n d o u t s l o p e d r o a d d e s i g n

. This

r e s e a r c h e m p h a s i z e d n e w r o a d c o n s t r u c t i o n a n d i n c o r p o r a t e d e r o s i o n c o n c e r n s a s a s i d e

constraint.

T a k i n g a s t r e a m r e s t o r a t i o n p e r s p e c t i v e

, M a d e j a n d o t h e r s ( 2 0 0 6 ) c o m p a r e d t h e

e f f e c t i v e n e s s o f a g e n e t i c a l g o r i t h m ( a h e u r i s t i c t e c h n i q u e ) w i t h d y n a m i c p r o g r a m m i n g

( a n e x a c t s o l u t i o n t e c h n i q u e ) t o a s s e s s t h e c o s t e f f e c t i v e n e s s o f r o a d r e m o v a l t r e a t m e n t s

o n a w a t e r s h e d s c a l e

. W h i l e b o t h s e a r c h t e c h n i q u e s p r o v i d e d s i m i l a r a n s w e r s

, t h e g e n e t i c15 a l g o r i t h m w a s d e e m e d t o h a v e s e v e r a l a d v a n t a g e s o v e r d y n a m i c p r o g r a m m i n g b e c a u s e i t

p r o v i d e s a s e t o f e f f e c t i v e s o l u t i o n s r a t h e r t h a n o n l y o n e s o l u t i o n

. A s a r e s u l t

, m anagers

h a v e a c h o i c e o f w h i c h s o l u t i o n t o u s e w h e n w i s h i n g t o a c c o u n t f o r o t h e r f a c t o r s b e s i d e s

j u s t s e d i m e n t s a v i n g s

. S e d i m e n t s a v i n g s a s s o c i a t e d w i t h v a r i o u s t r e a t m e n t s w a s

a c c o u n t e d f o r b y p h y s i c a l l y m e a s u r i n g v o i d s l e f t i n r o a d p r i s m

, n a t i v e h i l l s l o p e s

, a n d

channels following a 12

- year storm event.

M o d e l e d r o a d e r o s i o n p r e d i c t i o n s h a v e b e e n i n c o r p o r a t e d i n t o f o r e s t t r a n s p o r t a t i o n

p l a n n i n g p r o b l e m s

. T o d a t e

, a l l r e s e a r c h i n c o r p o r a t i n g t h e s e p r e d i c t i o n s h a s u s e d W E P P :

Road t o m o d e l r o a d s e d i m e n t

. Rackle y a n d C h u n g ( 2 0 0 8 ) a p p l i e d a d o l l a r a m o u n t t o

W E P P : R o a d e r o s i o n e s t i m a t e s t o i n c o r p o r a t e e n v i r o n m e n t a l c o n c e r n s i n t o

N E T W O R K 2 0 0 0

, a f o r e s t t r a n s p o r t a t i o n p l a n n i n g t o o l

. S i n c e e n v i r o n m e n t a l c o n s t r a i n t s

h a d t o b e a s s i g n e d a d o l l a r a m o u n t w i t h i n t h e i r m o d e l i n g f r a m e w o r k

, R a c k l e y a n d

Chung’s research provid ed an indirect assessment of these constraints.

I n a n o t h e r a p p l i c a t i o n o f W E P P : R o a d t o a f o r e s t t r a n s p o r t a t i o n p l a n n i n g p r o b l e m

,

C o n t r e r a s a n d o t h e r s ( 2 0 0 8 ) u s e d W E P P : R o a d s e d i m e n t p r e d i c t i o n s t o i n c o r p o r a t e r o a d

s e d i m e n t a s a s i d e c o n s t r a i n t i n t o a n A n t C o l o n y O p t i m i z a t i o n ( A C O ) m e t a h e u r i s t i c

.

While modeled s e d i m e n t w a s d i r e c t l y a s s e s s e d ( n o t a s s i g n e d a d o l l a r v a l u e )

, i t w a s n o t

the objective function of the planning problem.

N o s t u d i e s t o d a t e h a v e e x c l u s i v e l y e m p h a s i z e d s e d i m e n t c o n c e r n s a s s o c i a t e d w i t h

B M P i m p l e m e n t a t i o n o n e x i s t i n g f o r e s t r o a d n e t w o r k s

. W h i l e p r o c e s s

- based models have

b e e n u s e d t o e s t i m a t e e r o s i o n

, t h e y h a v e o n l y b e e n u s e d t o a s s e s s s i d e c o n s t r a i n t s i n

f o r e s t t r a n s p o r t a t i o n p l a n n i n g p r o b l e m s

. T h e l o g i c a l e v o l u t i o n o f w a t e r s h e d

- s c a l e r o a d

n e t w o r k p l a n n i n g p r o b l e m s i s t o f o r m u l a t e sedimentation c o n c e r n s a s o b j e c t i v e f u n c t i o n s16 within the planning problem

. F u r t h e r m o r e

, p r o c e s s

- b a s e d r o a d e r o s i o n p r e d i c t i o n s

, b e i n g

the current state

- of

- the

- art, c ould be used in the place of empirical equations.

T h o u g h m u l t i p l e h e u r i s t i c s c o u l d b e u s e d t o s o l v e s i m i l a r p l a n n i n g p r o b l e m s

,

s i m u l a t e d a n n e a l i n g ( K i r k p a t r i c k e t a l

. 1 9 8 3) i s a p r i m a r y c a n d i d a t e for a d d r e s s i n g f o r e s t

road B M P p l a n n i n g

. F o r u n c o m p l i c a t e d p l a n n i n g p r o b l e m s n o t c o n c e r n e d w i t h

t r a n s p o r t a t i o n n e t w o r k p l a n n i n g

, t h e u s e o f more c o m p l e x h e u r i s t i c s i s u n w a r r a n t e d

.

S i m u l a t e d a n n e a l i n g i s s i m p l e c o m p a r e d w i t h o t h e r h e u r i s t i c s

, y e t e f f e c t i v e

, and c a n b e

a p p l i e d t o a v a r i e t y o f o p t i m i z a t i o n p r o b l e m s ( K i r k p a t r i c k e t a l

. 1 9 8 3

, T a r p a n d H e l l e s

1997).

D e s c r i p t i o n o f S i m u l a t e d A n n e a l i n g : S i m u l a t e d a n n e a l i n g l o o s e l y r e s e m b l e s

cooling m e t a l l e a v i n g a f o r g e

. Beginning a n d e n d ing temperature s are specified before

starting the s earch

, a s i s c o o l i n g r a t e

. W h e n t h e s e a r c h s t a r t s

, t w o s o l u t i o n s a r e g e n e r a t e d

.

T h e s e c o n d o f t h e s e s o l u t i o n s i s a n e i g h b o r h o o d s o l u t i o n t o t h e i n i t i a l ( c u r r e n t ) s o l u t i o n

,

w h e r e o n e e l e m e n t o f t h e i n i t i a l s o l u t i o n h a s b e e n a l t e r e d

. T h e o b j e c t i v e f u n c t i o n v alues

for these two solutions are then compared.

I f t h e a l t e r n a t i v e ( n e w ) s o l u t i o n v a l u e i s i n d e e d b e t t e r t h a n t h e initial s o l u t i o n

, t h e

n e w s o l u t i o n i s s t o r e d a s t h e c u r r e n t s o l u t i o n

. T h e n e x t i t e r a t i o n o f t h e a l g o r i t h m

g e n e r a t e s a n e w s o l u t i o n b y again altering o n e e l e m e n t o f t h e c u r r e n t s o l u t i o n

. I n t h e

c a s e t h a t t h e a l t e r n a t i v e s o l u t i o n i s n o t b e t t e r t h a n t h e i n i t i a l s o l u t i o n

, a n a c c e p t a n c e

probability is generated using the following equation :17 Dependi n g o n w h e t h e r t h e o b j e c t i v e f u n c t i o n i s t o m i n i m i z e o r m a x i m i z e a v a l u e

,

t h e r e l a t i o n s h i p b e t w e e n t h e a c c e p t a n c e p r o b a b i l i t y a n d a r a n d o m l y g e n e r a t e d n u m b e r

w i l l d i c t a t e w h e t h e r t h e w o r s e n e w s o l u t i o n w i l l b e a c c e p t e d a n d u s e d a s t h e c u r r e n t

s o l u t i o n i n t h e n e x t a l g o r i t h m i t e r a t i o n

. I n a c c e p t i n g a w o r s e s o l u t i o n

, simulated

a n n e a l i n g p r o v i d e s f o r t h e p o s s i b i l i t y t h a t t h e w o r s e s o l u t i o n m a y s e r v e a s a l i n k t o a

better solution that would not be found as quickly using a random search.

A f t e r a s e t n u m b e r o f i t e r a t i o n s

, t e m p e r a t u r e i s c o o l e d a t t h e s e t c o o l i n g r a t e

. A s

t e m p e r a t u r e b e c o m e s s m a l l e r

, t h e i n t e r v a l o f d i f f e r e n c e b e t w e e n t h e n e w a n d c u r r e n t

t e m p e r a t u r e m u s t b e s m a l l e r i n o r d e r f o r a w o r s e s o l u t i o n t o b e a c c e p t e d

. T h i s c r e a t e s a

solution space that bec omes less variable as algorithm iterations increase and temperature

decreases. U p o n r e a c h i n g s t o p p i n g c r i t e r i a ( o f t e n d e f i n e d a s m a x i m u m n u m b e r o f

iterations or minimum temperature), the algorithm stops and a best solution is reported.

F i g u r e 1

. Example of solution value change with i t e r a t i o n n u m b e r i n a m i n i m i z a t i o n p r o b l e m using

simulated a nnealing optimization. 20 25 30 35 40 45

0 2000 4000 6000 8000 10000 12000 14000 16000 18000Bestsolutionvalue

Number of iterations18 S i m u l a t e d a nnealing h a s b e e n u s e d t o s o l v e c o m p l i c a t e d n a t u r a l r e s o u r c e p l a n n i n g

p r o b l e m s t h a t i n c l u d e both s p a t i a l a d j a c e n c y a n d t e m p o r a l c onstraints. Example

a pplications include forest harvest schedu ling ( e.g. L o c k w o o d a n d M o o r e 1 9 9 3

, L i u e t a l

.

2000 ) a n d land

- use allocation a s s o c i a t e d w i t h m i n e r e c l a m a t i o n ( A e r t s a n d H e u v e l i n k

2002)

. I n t e r m s o f r o a d

- r e l a t e d a p p l i c a t i o n s

, s i m u l a t e d a n n e a l i n g h a s b e e n u s e d t o

o p t i m i z e f o r e s t r o a d v e r t i c a l a l i g n m e n t w i t h i n f o r e s t r o a d c o n s t r u c t i o n d e c i s i o n s u p p o r t

t o o l s ( A k a y a n d S e s s i o n s 2 0 0 5 )

. Additionally, Coulter e t a l

. ( 2 0 0 5 ) u s e d s i m u l a t e d

a n n e a l i n g t o o p t i m i z e f o r e s t r o a d m a i n t e n a n c e and upgrade p r o j e c t s o n O r e g o n S t a t e

U n i v e r s i t y r e s e a r c h f o r e s t s

. T o d a t e

, n o p r o j e c t s h a v e a d d r e s s e d spatially

- explicit BMP

installation and maintenance scheduling w i t h t h e e x c l u s i v e i n t e n t i o n o f m i n i m i z i n g w a t e r

quality degradation using simulated annealing

.

1.3 Literature Review Summary

S u r f a c e h y d r o l o g y a s s o c i a t e d w i t h r o a d n e t w o r k s i s f a i r l y w e l l

- u n d e r s t o o d

. T o

a d d r e s s n e g a t i v e i m p a c t s a s s o c i a t e d w i t h r o a d s

, B M P s h a v e b e e n i m p l e m e n t e d o n r o a d

networks. E x a m p l e s o f B M P s u s e d o n f o r e s t r o a d s i n t h e L a k e T a h o e B a s in include

o u t s l o p i n g

, p a v i n g

, a n d d r a i n d i p s

. R o a d e r o s i o n m o d e l s c o m e i n m u l t i p l e d i f f e r e n t

forms, ranging from empirical to process

- based. Researchers have begun bridging the gap

b e t w e e n i d e n t i f i c a t i o n o f p r o b l e m a t i c r o a d s e g m e n t s a n d p l a n n i n g o f B M P

im p l e m e n t a t i o n

. T h e r e i s a l a c k o f p l a n n i n g t o o l s a v a i l a b l e f o r d i r e c t l y a d d r e s s i n g r o a d

s e d i m e n t a t i o n a n d p l a n n i n g a p p l i c a b l e B M P s o n e x i s t i n g r o a d n e t w o r k s

. C o m b i n i n g

process

- b a s e d r o a d e r o s i o n m o d e l i n g w i t h h e u r i s t i c o p t i m i z a t i o n

, s p e c i f i c a l l y s i m u l a t e d

a nnealing, provides a possible framework for this needed tool.19 1.4 References

Aerts, J., and Heuvelink, G. 2002. Using simulated annealing for resource allocation. Int.

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, Wyoming Nonpoint Source Management Plan Final: March 1997.25 2

. AN ANALYSIS OF WEPP: ROAD PARAMETER SENSITIVITY

2 .1 Abstract

W E P P : R o a d i s a u s e r

- f r i e n d l y i n t e r f a c e t o a p r o c e s s

- b a s e d r o a d e r o s i o n m o d e l

t h a t i s a p p l i c a b l e v i r t u a l l y a n y w h e r e i n t h e U

. S

. T h e s e n s i t i v i t y a n a l y s i s p r e s e n t e d h e r e

provides a perspective f o r i d e n t i f y i n g t h o s e p a r a m e t e r s t h a t a r e m o s t i m p o r t a n t t o c o l l e c t

a c c u r a t e l y d u r i n g r o a d s u r v e y s

. I n a d d i t i o n

, t h e a n a l y s i s p r o v i d e s i n s i g h t i n t o t h e c e n t r a l

p h y s i c a l c o n c e p t s t h a t d r i v e W E P P : R o a d p r e d i c t i o n s

. Forty r o a d s e g m e n t s w e r e

g e n e r a t e d w h e r e o n e p a r a m e t e r w a s a l t e r e d i n e a c h s e g m e n t f r o m i t s c o n t r o l v a l u e

.

Q u a n t i t a t i v e p a r a m e t e r s w e r e a l t e r e d t o p l u s a n d m i n u s 1 0 % a n d 3 0 % o f t h e i r c o n t r o l

value

. All 40 segments were input into WEPP: Road under all soil options using the same

climate.

W E P P : R o a d e r o s i o n r a t e e s t i m a t e s w e re s ubstantiall y d i f f e r e n t b e t w e e n s oil

t y p e s

. T h e s e d i f f e r e n c e s c o u l d b e e x p l a i n e d t h r o u g h a c o m b i n a t i o n o f s o i l cohesive

s t r e n g t h a n d p a r t i c l e s i z e

. W E P P : R o a d p r e d i c t e d a n i n c r e a s e i n s e d i m e n t l e a v i n g t h e

r o a d a n d s e d i m e n t l e a v i n g t h e b u f f e r w i t h a c h a n g e i n r o a d s u r f a c e f r o m n a t i v e t o p a v e d

.

Any c hange in rock content above 50% in WEPP: Road yield ed no change in erosion rate

predictions

. R o a d l e n g t h a n d w i d t h w e r e t h e m o s t s e n s i t i v e q u a n t i t a t i v e p a r a m e t e r i n p u t s

f o r e s t i m a t e s o f b o t h s e d i m e n t l e a v i n g t h e r o a d a n d s e d i m e n t l e a v i n g t h e b u f f e r

.

Generally, WEPP: Road estimates match ed published data

.26 2

. 2 Introduction

F o r e s t r o a d s f u l f i l l a c r i t i c a l s e r v i c e t h r o u g h p r o v i d i n g a c c e s s t o r e m o t e p u b l i c

a n d p r i v a t e l a n d s

, o f t e n i n r u g g e d t e r r a i n ( F o r m a n a n d A l e x a n d e r 1 9 9 8

, S w i t a l s k i e t a l

.

2003)

. W h i l e p r o v i d i n g i m p o r t a n t f u n c t i o n s

, f o r e s t r o a d s h a v e n u m e r o u s n e g a t i v e

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. g

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, S w i t a l s k i e t a l

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2 0 0 4

, F o r m a n a n d D e b l i n g e r 2 0 0 0 )

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. g

. J o n e s a n d G r a n t

1 9 9 6

, M a h o l l a n d 2 0 0 2

, L u c e 2 0 0 2 )

, a n d g e o m o r p h i c c o n s e q u e n c e s ( e

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. W e m p l e e t a l

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1996, Montgomery 1994

, Jones et al., 2000 )

.

R u n o f f a n d e r o s i o n p r e d i c t i o n ( h y d r o l o g i c ) m o d e l s a r e o n e m e t h o d b y w h i c h

c o n s e q u e n c e s o f w a t e r s h e d e r o s i o n c a n b e m i t i g a t e d

. W i t h h y d r o l o g i c m o d e l s

, f u t u r e

e v e n t s c a n b e f o r e c a s t a n d p r e v i o u s h y d r o l o g i c e v e n t s c a n b e a n a l y z e d

. M a n a g e r s a n d

p l a n n e r s c a n m i n i m i z e e n v i r o n m e n t a l d a m a g e r e s u l t i n g f r o m m a n a g e m e n t decis ions

(Singh and Woolhiser 2002). Through prediction of sediment loss, thousands of dollars in

e c o n o m i c l o s s m a y b e p r e v e n t e d a s a r e s u l t o f p r o p e r t y d a m a g e

, i n c o r r e c t p l a c e m e n t o f a

r o a d o r d r a i n a g e s t r u c t u r e

, o r r e s t o r a t i o n o f a n a r e a f o l l o w i n g a n i l l

- con ceived

management decision.

F o r y e a r s

, e m p i r i c a l m o d e l s s u c h a s t h e U n i v e r s a l S o i l L o s s E q u a t i o n

( W i s c h m e i e r a n d S m i t h 1 9 7 8 )

, a n d R e v i s e d U n i v e r s a l S o i l L o s s E q u a t i o n ( R e n a r d e t a l

.

1 9 9 7 ) w e r e w i d e l y u s e d t o m a k e e r o s i o n e s t i m a t e s

. E m p i r i c a l m o d e l s

, w h i l e s i m p l e

, d o

n o t m a k e f u l l u s e o f o u r u n d e r s t a n d i n g o f h y d r o l o g i c s y s t e m d y n a m i c s ( R e n s c h l e r 2003).

Process

- a n d p h y s i c s

- b a s e d m o d e l s

, i n c o n t r a s t

, i n c o r p o r a t e k n o w l e d g e a b o u t t h e p h y s i c s

o f a s y s t e m t o d e r i v e more detailed y e t g e n e r a l i z a b l e p r e d i c t i o n s o f r u n o f f a n d s e d i m e n t

( R e n s c h l e r 2 0 0 3 ). The W a t e r E r o s i o n P r e d i c t i o n P r o j e c t ( W E P P ) ( F l a n a g a n a n d Nearing27 1995) i s o n e o f m a n y p r o c e s s

- based h y d r o l o g i c m o d e l s c u r r e n t l y i n u s e

. Originally

d e s i g n e d f o r a g r i c u l t u r e

, i t h a s b e e n a d a p t e d f o r u s e i n f o r e s t c o n d i t i o n s ( E l l i o t e t a l

.

2 0 0 6 ) a n d h a s b e e n a p p l i e d t o a v a r i e t y o f w a t e r s h e d s w i t h s u c c e s s a t multiple scales

(Amore et al. 2004).

T o a d d r e s s t h e n e e d f o r a r e l a t i v e l y s i m p l e

, u s e r

- f r i e n d l y r o a d e r o s i o n m o d e l

,

W E P P : R o a d w a s d e v e l o p e d b y t h e R o c k y M o u n t a i n Researc h S t a t i o n i n M o s c o w

, I D

(Elliot 2 0 0 4 )

. W E P P : R o a d p r o v i d e s a w e b

- b a s e d g r a p h i c u s e r i n t e r f a c e r e q u i r i n g f e w

i n p u t p a r a m e t e r s

, m a n y o f w h i c h c a n b e a c q u i r e d w i t h o u t f i e l d s u r v e y s

. T h e i n t e r f a c e

a l l o w s u s e r s f r o m a v a r i e t y o f t e c h n i c a l b a c k g r o u n d s t o e f f e c t i v e l y p r e d i c t i m p a c t s

a s s o c i a t e d w i t h r o a d

- r e l a t e d m a n a g e m e n t d e c i s i o n s

. B y p r o v i d i n g a r a n g e o f c l i m a t e s

( a n d t h e o p t i o n t o a l t e r c l i m a t e s t o r e p r e s e n t s i t e

- s p e c i f i c c o n d i t i o n s )

, s u r f a c e t y p e s

,

traffic levels, and road designs, WEPP: Road is applica ble virtually anywhere in the U.S.

U n d e r s t a n d i n g h o w a g i v e n p a r a m e t e r w i l l a f f e c t r o a d e r o s i o n e s t i m a t e s i s

i m p o r t a n t f o r m o d e l u s e r s

. G i v e n l i m i t e d r e s o u r c e s

, W E P P : R o a d u s e r s m a y b e u n a b l e t o

m e a s u r e a l l n e c e s s a r y i n p u t p a r a m e t e r s i n t h e f i e l d a t e v e r y s i t e o f i n t e r e s t

. K n o w i n g

which parameters are essential to accurately measure gives users a better idea of where to

b e s t a l l o c a t e r e s o u r c e s

. I n a d d i t i o n

, i t i s i m p o r t a n t t o u n d e r s t a n d s o u r c e s o f p r e d i c t i o n

v a r i a b i l i t y i n a s s e s s i n g m o d e l o u t p u t s w h e n t r y i n g t o a c h i e v e t h e b e s t p o s s i b l e e r o s i o n

predictions.

T h e s e n s i t i v i t y a n a l y s i s p r e s e n t e d h e r e f i l l s t h i s n e e d

. F r o m t h i s s e n s i t i v i t y

a n a l y s i s

, i d e n t i f i e d s o u r c e s o f p r e d i c t i o n v a r i a b i l i t y c a n i n f o r m u s e r s o f t h e g e n e r a l

c o n c e p t s t h a t d r i v e t h e W E P P m o d e l

. A d d i t i o n a l l y

, W E P P : R o a d ’ s p r e d i c t i v e c a p a b i l i t y

can be validated by analyzing whether predictions agree with current literature.28 2

. 3 Description of WEPP: Road I nterface:

W E P P : R o a d i s a n i n t e r f a c e t o t h e W E P P m o d e l s p e c i f i c a l l y c a t e r i n g t o r o a d

h y d r o l o g y a n d s e d i m e n t p r o d u c t i o n e s t i m a t i o n

. N u m e r o u s c l i m a t e b a s e s t a t i o n r e c o r d s

a r e a v a i l a b l e i n t h e c l i m a t e l i b r a r y

. T o a c c o m m o d a t e l o c a l c l i m a t e v a r i a t i o n

, b a s e s t a t i o n

d a t a c a n b e altered u s i n g t h e P arameter

- e l e v a t i o n R e g r e s s i o n b a s e d o n I n d e p e n d e n t

S l o p e s ( PRISM ) model, w h i c h m o d i f i e s precipitation b a s e d o n l i n e a r l y r e g r e s s e d

r e l a t i o n s h i p s w i t h e l e v a t i o n ( D a l y e t a l

. 2 0 0 4 )

. W E P P : R o a d e s t i m a t e s r u n o f f a n d s o i l

l o s s o n t h r e e o v e r l a n d f l o w e l e m e n t s : t h e r o a d b e d i t s e l f

, a f i l l s l o p e

, a n d t h e r o a d b u f f e r

( hill s l o p e a r e a b e t w e e n t h e b a s e o f t h e f i l l s l o p e a n d t h e n e a r e s t w a t e r s o u r c e ) ( E l l i o t e t

a l

. 1 9 9 9 )

. F o u r s o i l t y p e s c a n b e m o d e l e d b y W E P P : R o a d : c l a y l o a m

, s i l t l o a m

, s a n d y

l o a m

, a n d l o a m

. F o u r r o a d d e s i g n s ( i n s l o p e d

, b a r e d i t c h

, i n s l o p e d

, v e g e t a t e d d i t c h

,

o u t s l o p e d

, u n r u t t e d

, a n d o u t s l o p e d

, r u t t e d )

, t h r e e r o a d s u r f a c e t y p e s ( n a t i v e

, g r a v e l e d

, o r

p a v e d )

, a n d t h r e e t r a f f i c l e v e l s ( n o n e

, l o w

, a n d h i g h ) a r e p r o v i d e d a s o p t i o n s i n the

W E P P : R o a d i n t e r f a c e

. O t h e r i n p u t p a r a m e t e r s i n c l u d e r o a d g r a d i e n t

, r o a d l e n g t h

, r o a d

width, fill slope gradient, fill slope length, buffer gradient, buffer length, and percent rock

content ( d e f i n e d a s t h e p e r c e n t v o l u m e o f r o c k f r a g m e n t s g r e a t e r t h a n 2 m m i n d i a m e t e r

i n t h e s o i l s u b s t r a t e (H

. R h e e p e r s o n a l c o m m u n i c a t i o n ) )

. W h i l e t h e d e f a u l t s i m u l a t i o n

time is 30 years, the user can specify longer time periods if desired (Table 1)

.

W E P P : R o a d o u t p u t s i n c l u d e a s u m m a r y o f i n p u t values a s w e l l a s p r e d i cted

r u n o f f f r o m r a i n e v e n t s

, p r e d i c t e d r u n o f f f r o m w i n t e r s t o r m e v e n t s

, s e d i m e n t l e a v i n g t h e

road prism (road), and sediment leaving the buffer

.29 Table 1. WEPP: Road input parameters and possible value s or parameter range s.

WEPP: Road i nput

parameter Possible values/allowable

range

Climate N/A

Soil type Silt loam

Sandy loam

Clay loam

Loam

Road design Insloped, bare ditch

Insloped, vegetated or

rocked ditch

Outsloped, unrutted

Outsloped, rutted

Surface type Native

Graveled

Paved

Traffic level None

Low

High

Road width 1 ft

- 300 ft

Road length 1 ft

- 999 ft

Road gradient .3%

- 99%

Fill slope length 1 ft

- 999 ft

Fill slope gradient .3%

- 99%

Buffer length 1 ft

- 999 ft

Buffer gradient .3%

- 99%

Coarse rock content 0%

- 10 0%

Years of simulation time 1 yr

- 200 yrs

2

. 4 Methods

W E P P : R o a d i n p u t s f o r t h i s a n a l y s i s w e r e c h o s e n b a s e d o n a v e r a g e v a l u e s

frequent l y s e e n o n f o r e s t r o a d s i n t h e w e s t e r n U n i t e d S t a t e s

. T h e c o n t r o l s e g m e n t c a n b e

found in Table 2

.30 Table 2

. Control road segment used for WEPP: Road sensitivity analysis.

Design Surface,

traffic Road

grad

(%) Road

length

(ft) Road

width

(ft) Fill

grad

(%) Fill

length

(ft) Buff

grad

(%) Buff

length

(ft) Rock

cont

(%)

Insloped,

bare

ditch native

low 7 300 12 50 10 20 300 50

A f t e r e s t a b l i s h i n g a c o n t r o l s e g m e n t

, n e w r o a d s e g m e n t s w e r e created

, e a c h with

one input p a r a m e t e r a l t e r e d f r o m t h e c o n t r o l

. Q u a l i t a t i v e p a r a m e t e r s ( r o a d d e s i g n

,

s u r f a c e

, a n d t r a f f i c l e v e l ) w e r e a l t e r e d s u c h t h a t e v e r y p o s s i b l e p a r a m e t e r v a l u e w a s

represented in a segment. Each quantitative parameter was altered to plus and minus 10%

a n d 3 0 % o f t h e c o n t r o l p a r a m e t e r v a l u e

. I n d o i n g s o

, a w i d e r a n g e o f f o r e s t r o a d

c o n d i t i o n s c o m m o n l y s e e n o n t h e g r o u n d c o u l d b e e v a l u a t e d

. U s i n g t h e s e c r i t e r i a

, a t o t a l

of 40 test segments were developed. Interaction between input parameters was not tested.

T h e 4 0 s e g m e n t s w e r e r u n i n W E P P : R o a d B a t c h

, a n a l t e r n a t i v e W E P P : R o a d

i n t e r f a c e w h i c h a l l o w s t h e u s e r t o e s t i m a t e s e d i m e n t l e a v i n g t h e r o a d a n d b u f f e r f o r u p t o

200 segments simultaneously. All 40 segments were run with each of the four soil texture

o p t i o n s

. “ T A H O E C A ” b a s e s t a t i o n c l i m a t e d a t a ( a v a i l a b l e i n t h e W E P P : R o a d B a t c h

c l i m a t e l i b r a r y ) w a s u s e d f o r t h e s i m u l a t i o n

. M o n t h l y a v e r a g e p recip i t a t i o n v a l u e s f r o m

this base station data w ere increased using PRISM based on elevation at a central location

w i t h i n t h e G l e n b r o o k C r e e k w a t e r s h e d

, N V

. ( F o r j u s t i f i c a t i o n o f s t u d y s i t e

, s e e C h a p t e r

3.3

. )31 2

. 5 Results/Discussion

A c o m p a r i s o n o f c o n t r o l s e g m e n t e r o s i o n p r e d i c t i o n s f o r e a c h s o i l t y p e i s s h o w n

i n T a b l e 3

. L o a m s o i l s we r e p r e d i c t e d t o p r o d u c e g r e a t e r t h a n d o u b l e t h e s e d i m e n t

l e a v i n g t h e r o a d i n s a n d y l o a m s o i l s

. C l a y l o a m a n d s i l t l o a m s o i l s w e r e p r e d i c t e d t o

p r o d u c e 1

. 5 a n d 1

. 9 t i m e s m o r e s e d i m e n t l e a v i n g t h e r o a d t h a n s a n d y l o a m s o i l s

,

respectively. W E P P : R o a d e s t i m a t e d 2

. 4 t i m e s m o r e s e d i m e n t l e a v i n g t h e b u f f e r i n c l a y

loam t h a n i n s a n d y l o a m s o i l s a n d a p p r o x i m a t e l y 1

. 5 t i m e s m o r e s e d i m e n t l e a v i n g t h e

b u f f e r i n s i l t l o a m a n d l o a m s o i l s t h a n i n s a n d y l o a m s o i l s

. R e s e a r c h s u g g e s t s t h a t f o r e s t

s o i l s w i t h h i g h e r s i l t c o n t e n t s a r e m o r e r e a d i l y e r o d i b l e ( L u c e a n d B l a c k 2 0 0 1 a ),

indicating that WEPP: Road estimates match empirical studies.

Table 3 . WE PP: Road control segment predictions.

Clay

l oam Silt

loam Sandy

loam Loam

Sediment leaving

road (lbs) 1002 1302 658 1342

Sediment leaving

buffer (lbs) 78 49 33 50

2 .5 a Qualitative parameters :

Figure 2 s h o w s W E P P : R o a d p r e d i c t i o n s o f s e d i m e n t l e a v i n g t h e r o a d f o r t h e f o u r

d i f f e r e n t r o a d d e s i g n t e m p l a t e s a v a i l a b l e i n t h e m o d e l

. T h e i n s l o p e d

, b a r e d i t c h r o a d

design w a s p r e d i c t e d t o p r o d u c e m o r e s e d i m e n t l e a v i n g t h e r o a d p e r y e a r t h a n a n y o t h e r

r o a d d e s i g n

. T h e d i f f e r e n c e i n s e d i m e n t p r e d i c t i o n b e t w e e n o u t s l o p e d

, u n r u t t e d a n d

outsloped, rutted road profiles reflects the importance of proper maintenance (Swift 1984

,

Grigal 2000 )

.32 M o d e l e d b e h a v i o r o f t h e d i f f e r e n t s o i l t y p e s a c r o s s t h e f o u r r o a d d e s i g n s w a s

c o n s i s t e n t e x c e p t f o r s a n d y l o a m o n t h e o u t s l o p e d

, u n r u t t e d r o a d s e g m e n t

. Greater

s e d i m e n t l e a v i n g t h e r o a d i n s a n d y l o a m s o i l s r e l a t i v e t o o t h e r s o i l t y p e s c o u l d b e

a t t r i b u t e d t o t h e l o w e r c o h e s i v e s t r e n g t h o f s a n d y l o a m c o m p a r e d t o t h e o t h e r s o i l t y p e s

(B ra dy 1 9 9 0 )

. A s a r e s u l t

, s a n d y l o a m c a n b e m o r e e a s i l y e n t r a i n e d t h a n t h e o t h e r s o i l

t y p e s o v e r s h o r t d i s t a n c e s

. C o n t i n u o u s f l o w p a t h l e n g t h o n t h e r o a d b e d i s s h o r t e s t o n t h e

o u t s l o p e d

, u n r u t t e d r o a d d e s i g n

. A s s u m i n g t h a t s h o r t f l o w p a t h s f a v o r g r e a t e r c o a r s e s o i l

s e d i m e n t t r a n s p o r t

, s i n c e c o a r s e r ( s a n d i e r ) s o i l s a r e d e p o s i t e d a f t e r t r a v e l i n g s h o r t e r

distances relative to other soil types, WEPP: Road predictions are appropriate.

P r e d i c t i o n s o f s e d i m e n t l e a v i n g t h e b u f f e r ( F i g u r e 3 ) d e m o n s t r a t e t h e u t i l i t y of

o u t s l o p i n g r o a d s e g m e n t s a s a B e s t M a n a g e m e n t P r a c t i c e t h a t m i n i m i z e s r o a d s e d i m e n t

.

T h i s m o d e l e d r e s u l t i s b a c k e d b y p u b l i s h e d l i t e r a t u r e ( M e g a h a n a n d K e t c h e s o n 1 9 9 6

,

L u c e a n d B l a c k 2 0 0 1 a

, E l l i o t e t a l

. 2 0 0 9 )

. W i t h t h e e x c e p t i o n o f c l a y l o a m

, p r e d i c t e d

s e d i m e n t l e a v i n g t h e b u f f e r w a s s i m i l a r o r n e a r l y i d e n t i c a l b e t w e e n i n s l o p e d

, v e g e t a t e d

d i t c h p r o f i l e s a n d o u t s l o p e d

, r u t t e d p r o f i l e s

. C l a y l o a m

, w i t h a s m a l l e r p a r t i c l e s i z e

d i s t r i b u t i o n r e l a t i v e t o t h e o t h e r s o i l t y p e s

, c a n b e e n t r a i n e d o v e r l o n g e r d i s t a n c e s g i v e n

the same amount of runoff.33 Figure 2 . WEPP: Road predictions of sediment leaving the road under four road designs.

Figure 3 . WEPP: Road predictions of sediment leaving the buffer under four road designs.

W E P P : R o a d p r e d i c t i o n s o f s e d i m e n t l e a v i n g t h e r o a d in d i f f e r e n t s u r f a c e t y p e s

a r e s h o w n i n F i g u r e 4

. P r e d i c t i o n s i n d i c a t e d t h a t g r a v e l e d r o a d s u r f a c e s a r e m o r e

e f f e c t i v e a t r e d u c i n g s e d i m e n t l e a v i n g t h e r o a d t h a n p a v e m e n t

. S i n c e t h e r o a d d e s i g n i n

t h e c o n t r o l s e g m e n t w a s i n s l o p e d w i t h a b a r e d i t c h

, a l l s e d i m e n t l e a v i n g t h e r o a d o n

p a v e d s e g m e n t s m u s t b e a t t r i b u t e d t o d i t c h e r o s i o n

. I n a l l c a s e s

, p a v e m e n t i n c r e a s e d 0 200 400 600 800 1000 1200 1400 1600

Insloped,

bare ditch Outsloped,

unrutted Insloped,

vegetated

ditch Outsloped,

ruttedSedimentleavingroadperyear,lbs

Road design clay loam

silt loam

sandy loam

loam

0 10 20 30 40 50 60 70 80 90

Insloped,

bare ditch Outsloped,

unrutted Insloped,

vegetated

ditch Outsloped,

ruttedSedimentleavingthebufferperyear,lbs

Road design clay loam

silt loam

sandy loam

loam34 s e d i m e n t l e a v i n g t h e r o a d

, w i t h t h e g r e a t e s t i n c r e a s e b e i n g i n s a n d y l o a m s o i l s

.

P a v e m e n t

, b e i n g e s s e n t i a l l y i m p e r v i o u s t o i n f i l t r a t i o n

, g e n e r a t e s m o r e a n d f l a s h i e r r u n o f f

t h a n g r a v e l e d o r n a t i v e s u r f a c e r o a d s

. D e s p i t e h a v i n g l e s s a v a i l a b l e s o u r c e s e d i m e n t

,

W E P P : R o a d p r e d i c t i o n s i n d i c a t e t h a t p a v e d s e g m e n t r u n o f f c a n b e s u b s t a n t i a l e n o u g h t o

prod u c e g r e a t e r s e d i m e n t l e a v i n g t h e r o a d f r o m d i t c h e r o s i o n a l o n e t h a n t o t a l s e d i m e n t

l e a v i n g t h e r o a d f r o m a n a t i v e s u r f a c e s e g m e n t

. S a n d y l o a m

, b e i n g m o r e r e a d i l y

entrained, will produce more sediment leaving paved road segments than other soil types.

WEPP : R o a d predicted s e d i m e n t l e a v i n g t h e b u f f e r i n l o a m s o i l s o n p a v e d

segments to be less than that on native surface segments; the same holds true for silt loam

soils (Figure 5) . Sandy loam and clay loam do not follow this trend. The greater predicted

runof f l e a v i n g p a v e d r o a d s e g m e n t s c a n e a s i l y e n t r a i n c l a y l o a m f o r l o n g e r d i s t a n c e s

p r i o r t o d e p o s i t i o n

, t h e r e b y e x p l a i n i n g t h e i n c r e a s e i n s e d i m e n t l e a v i n g t h e b u f f e r o n c l a y

loam segments relative to silt loam and loam soils. As for sandy loam, t he combinati on of

i n c r e a s e d r u n o f f a n d m o r e e n t r a i n e d s e d i m e n t l e a v i n g t h e r o a d r e l a t i v e t o o t h e r s o i l t y p e s

could explain the disparate amount of sediment leaving the buffer in this soil type

.

R e i d a n d D u n n e o b s e r v e d p a v e d s e g m e n t s p r o d u c i n g l e s s t h a n 1 % o f s e d i m e n t

g e n e r a t e d o n a h e a v i l y u s e d g r a v e l s e g m e n t ( 1 9 8 4 )

. I n a n o t h e r s t u d y c o n d u c t e d i n

G e o r g i a a n d S o u t h C a r o l i n a

, p a v e d r o a d s e g m e n t s w e r e f o u n d t o p r o d u c e l e s s t h a n 5 % o f

the Total Suspended Solids (TSS) leaving unimproved gravel road segments (Clinton and

Vo s e 2 0 0 3 )

. T h e s e r e s u l t s w e r e f o u n d o n s l o p e s g r e a t e r t h a n 2 0 % i n u n k n o w n s o i l t y p e s

w i t h r i p r a p o n d r a i n a g e s u r f a c e s

. F o r b o t h o f t h e s e s t u d i e s

, d i t c h r o u g h n e s s a n d

maintenance regime assumptions were not clearly conveyed

.35 W E P P : R o a d i s n o t c a p a b l e o f m o d e l i n g e f f e c t s o f B M P s o n d o w n s l o p e d r a i n a g e

s u r f a c e s

, w h i c h m a y e x p l a i n b u f f e r e r o s i o n p r e d i c t i o n s b e i n g g r e a t e r t h a n t h o s e p r e d i c t e d

b e l o w o t h e r s u r f a c e t y p e s

. T o c l a r i f y w h e t h e r t h e b a r e d i t c h c o m p o n e n t o f t h e r o a d

d e s i g n w a s r e s p o n s i b l e f o r e l e v a t e d W E P P : R o a d e r o s i o n p r e d i c t i o n s f r o m t h e r o a d

surface

, t h e p a v e d s e g m e n t r o a d d e s i g n w a s c h a n g e d t o “ i n s l o p e d

, v e g e t a t e d o r r o c k e d

d i t c h ” a n d a g a i n m o d e l e d f o r e r o s i o n u s i n g W E P P : R o a d

. T r a f f i c l e v e l o n t h e g r a v e l e d

s u r f a c e s e g m e n t w a s a l t e r e d t o “ h i g h ” a n d m o d e l e d a g a i n u s i n g W E P P : R o a d

. F i g u r e 4

also includes t h e s e m o d e l p r e d i c t i o n s

. W E P P : R o a d p r e d i c t e d l e s s s e d i m e n t l e a v i n g t h e

r o a d f r o m t h e p a v e d s e g m e n t t h a n t h e h i g h t r a f f i c g r a v e l e d s e g m e n t

, b u t p r e d i c t i o n s

ranged from 54

- 85% of that found on high traffic graveled segments.

W h i l e n o c o n c l u s i o n c a n b e m a d e r e g a r d i n g W E P P : R o a d ’ s p r e d i c t i o n o f

s e d i m e n t l e a v i n g p a v e d s e g m e n t r o a d buffer s

, W E P P : R o a d may b e o v e r e s t i m a t i n g

s e d i m e n t l e a v i n g t h e d i t c h e s o f p a v e d r o a d s e g m e n t s

. N o t a l l p a r a m e t e r s a s s o c i a t e d w i t h

f i e l d t e s t e d s e g m e n t s

, h o w e v e r

, a r e k n o w n

. M o r e i n f o r m a t i o n a b o u t t h e c o n d i t i o n o f

p a v e d s e g m e n t s u s e d i n f i e l d s t u d i e s

, e s p e c i a l l y r e g a r d i n g t h e i r ditches

, m u s t b e

c o m p a r e d t o W E P P : R o a d m o d e l a s s u m p t i o n s t o detect wheth e r s e d i m e n t l e a v i n g t h e

road is truly being overestimated

.36 Figure 4

. WEPP: Road predictions of s ediment leaving road under different road surface types. All road

designs are insloped, bare ditch except for the paved segment with an insloped and vegetated or rocked

ditch. All segments were modeled using low traffic assumptions except for one graveled segment.

Figure 5 . WEPP: Road predictions of sediment leaving the buffer under three road surface types.

E f f e c t s o f t r a f f i c l e v e l o n W E P P : R o a d p r e d i c t i o n s c a n b e f o u n d i n F i g u r e s 6 a n d

7

. W E P P : R o a d p r e d i c t e d a n e x p o n e n t i a l i n c r e a s e i n s e d i m e n t l e a v i n g t h e r o a d a n d

s e d i m e n t l e a v i n g t h e b u f f e r w i t h i n c r e a s e s i n t r a f f i c

. W E P P : R o a d a s s u m e s h i g h t r a f f i c t o

b e e q u i v a l e n t t o s e d i m e n t a v a i l a b l e o n a n e w l y c o n s t r u c t e d r o a d o r d u r i n g a n a c t i v e

l o g g i n g o p e r a t i o n

. L o w t r a f f i c

, i n c o n t r a s t

, i s a s s u m e d t o g e n e r a t e o n e q u a r t e r o f t h e

s e d i m e n t g e n e r a t e d d u r i n g a n a c t i v e l o g g i n g o p e r a t i o n ( B

. E l l i o t p e r s o n a l 0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000

Native Graveled,

low traffic Paved Insloped,

vegetated

ditch paved Graveled,

high trafficSedimentleaivngroadpearyear,lbs clay loam

silt loam

sandy loam

loam

0 10 20 30 40 50 60 70 80 90 100

Native Graveled PavedSedimentleavingbufferperyear,lbs

Road surface clay loam

silt loam

sandy loam

loam37 c o m m u n i c a t i o n )

. W i t h s u c h a s s u m p t i o n s

, W E P P : R o a d p r e d i c t i o n s r e l a t e d t o t r a f f i c

f o l l o w c l o s e l y w i t h l i t e r a t u r e

- s u p p o r t e d f i n d i n g s ( e

. g

. R e i d a n d D u n n e 1 9 8 4

, F o l t z 1 9 9 6

,

Bilby et al. 1989).

Figure 6

. WEPP: Road predictions of sediment leaving the road under no traffic, low traffic, and high

traffic scenarios.

Figure 7 . WEPP: Road predictions of sediment leaving the buffer under no traffic, low traffic, and high

traffic scenarios. 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

None Low HighSedimentleavingtheroadperyear,lbs

Traffic level clay loam

silt loam

sandy loam

loam

0 20 40 60 80 100 120 140 160 180 200

None Low HighSedimentleavingbufferperyear,lbs

Traffic level clay loam

silt loam

sandy loam

loam38 2

. 5 b Quantitati ve parameters:

I n a l l t h r e e s o i l t y p e s

, s e n s i t i v i t y t r e n d s b e t w e e n p a r a m e t e r s a r e i d e n tical.

Accordingly, only WEPP: R oad predictions in silt loam soil are shown below.

R o a d l e n g t h w a s t h e m o s t s e n s i t i v e o f t h e s i x p a r a m e t e r s i n t e r m s o f c h a n g e i n

predic ted sediment leaving the road, followed by road gradient and road width (Figure 8 )

.

T h e s e r e s u l t s s u g g e s t t h a t B M P s w h i c h r e d u c e s e g m e n t l e n g t h s t a n d t o r e d u c e s e d i m e n t

l e a v i n g t h e r o a d m o r e t h a n B M P s t h a t a l t e r o t h e r q u a n t i t a t i v e r o a d p a r a m e t e r s

. F i l l s l o pe

g r a d i e n t a n d l e n g t h w e r e p r e d i c t e d t o h a v e m i n i m a l e f f e c t o n s e d i m e n t l e a v i n g t h e r o a d

.

Rock content, if greater than 50%, has no effect on predicted sediment leaving the road.

F r e e r o c k s o n t h e s o i l s u r f a c e h a v e b e e n s h o w n t o d i s s i p a t e t h e k i n e t i c e n e r g y o f

r u n o f f ( D e s c r o i x e t a l

. 2 0 0 1 )

. R e s e a r c h h a s f o u n d f o r e s t s o i l s w i t h r o c k f r a g m e n t c o v e r

g r e a t e r t h a n 5 0 % t o t a k e l o n g e r t o g e n e r a t e r u n o f f a n d t o p r o t e c t f i n e r s u b s u r f a c e s o i l s

f r o m b e i n g e n t r a i n e d b y r u n o f f ( C e r d a  ́ 2 0 0 1 )

. M a r t í n e z

- Z a v a l a a n d J o r d á n r e p o r t a n

increase in infiltration rate and exponential decrease in soil loss rate with increase in rock

f r a g m e n t c o v e r ( 2 0 0 8 )

. W h i l e t h e r e s e a r c h c i t e d a b o v e w o u l d s u g g e s t t h a t W E P P : R o a d

p r e d i c t i o n s d i s a g r e e w i t h p u b l i s h e d l i t e r a t u r e

, K i d w e l l a n d o t h e r s ( 1 9 9 7 ) r e p o r t

, a s p e r

P o e s e n e t a l

. ’ s f i n d i n g s ( 1 9 9 0 )

, t h a t d e g r e e o f e m b e d d e d n e s s a c t s a s a c o n t r o l o n

i n f i l t r a t i o n r a t e ; r o c k f r a g m e n t s e m b e d d e d u n d e r t h e s o i l s u r f a c e r e s t r i c t i n f i l t r a t i o n r a t e

a n d a l s o t h e r e f o r e t i m e t o p r o d u c t i o n o f o v e r l a n d f l o w

. T h i s p h y s i c a l c o n t r o l a p p e a r s t o

b e t h e d r i v e r b e h i n d W E P P : R o a d p r e d i c t i o n s of s e d i m e n t p r o d u c t i o n a t p e r c e n t r o c k

c o n t e n t s l e s s t h a n 5 0 %

. W E P P : R o a d u s e s default value s when model ing roads

c o n t a i n i n g 5 0 % r o c k c o n t e n t o r g r e a t e r ( H

. R h e e p e r s o n a l communication)

, e x p l a i n i n g

the lack of change in predicted erosion at rock content s greater than 50%

.39 Figure 8 . WEPP: Road predictions of sediment leaving the road in silt loam soil under multiple quantitative

parameter scenarios. Mult iplier represents control value of a given parameter (1) as well as +/

- 10% (1.1

and .9) and +/

- 30% (1.3 and .7) that value

.

Figure 9 . WEPP: Road predictions of sediment leaving the buffer in silt loam soil under multiple

quantitative parameter scenarios. Multiplier re presents control value of a given parameter (1) as well as +/

- 10% (1.1 and .9) and +/

- 30% (1.3 and .7) that value.

Since all parameters c o n t r o l l i n g s e d i m e n t l e a v i n g t h e r o a d i n f l u e n c e s e d i m e n t

v o l u m e a v a i l a b l e f o r d o w n s l o p e t r a n s p o r t

, a l l e i g h t q u a n t i t a t i v e p a r a m e t e r s c o u l d 0 500 1000 1500 2000 2500

0.7 0.9 1 1.1 1.3Sedimentleavingroadperyear,lbs

Multiplier road gradient

road length

road width

rock content

fill slope gradient

fill slope length

0 20 40 60 80 100 120 140

0.7 0.9 1 1.1 1.3Sedimentleavingbufferperyear,lbs

Multiplier road gradient

road length

road width

fill slope gradient

fill slope length

buffer gradient

buffer length

rock content40 p o t e n t i a l l y a f f e c t W E P P : R o a d p r e d i c t i o n s f o r s e d i m e n t l e a v i n g t h e b u f f e r ( M e g a h a n a n d

K e t c h e s o n 1 9 9 6 )

. F o r t h a t r e a s o n

, a l l q u a n t i t a t i v e p a r a m e t e r s h a v e b e e n i n c l u d e d i n

F i g u r e 9

. A s w i t h s e d i m e n t l e a v i n g t h e r o a d

, r o a d l e n g t h w a s t h e m o s t s e n s i t i v e

p a r a m e t e r

. B u f f e r g r a d i e n t a n d r o a d w i d t h b o t h h a d a p o s i t i v e r e l a t i o n s h i p w i t h s e d i m e n t

l e a v i n g t h e b u f f e r

. B u f f e r l e n g t h

, i n c o n t r a s t

, h a d a n e g a t i v e r e l a t i o n s h i p w i t h s e d i m e n t

l e a v i n g t h e b u f f e r

. B u f f e r l e n g t h w a s m o r e s e n s i t i v e t h a n b o t h b u f f e r g r a d i e n t a n d r o a d

width. A s w i t h p r e d i c t i o n s f o r s e d i m e n t l e a v i n g t h e r o a d

, f i l l s l o p e l e n g t h a n d f i l l s l o p e

g r a d i e n t h a d l i t t l e b e a r i n g o n s e d i m e n t l e a v i n g t h e b u f f e r

. R o c k c o n t e n t h a d t h e s a m e

e f f e c t o n s e d i m e n t l e a v i n g t h e b u f f e r a s i t d i d w i t h s e d i m e n t l e a v i n g t h e r o a d ; t h e r e w a s

n o c h a n g e i n s e d i m e n t l e a v i n g t h e b u f f e r w i t h c h a n g e i n r o c k c o n t e n t a b o v e 5 0 % d u e t o

WEPP: Road model assumptions

.

M u l t i p l e s t u d i e s h i g h l i g h t t h e i m p o r t a n c e o f r o a d s e g m e n t l e n g t h a n d a lso

i n t e r a c t i v i t y w i t h s l o p e o n the r o a d b e d a n d b u f f e r i n e x p l a i n i n g s e d i m e n t t r a n s p o r t f r o m

f o r e s t r o a d s ( e

. g

. L u c e a n d B l a c k 1 9 9 9

, L u c e a n d B l a c k 2 0 0 1 a

, E l l i o t e t a l

. 2 0 0 9 )

. I n

a d d i t i o n

, C o e ( 2 0 0 6 ) f o u n d s e g m e n t s u r f a c e a r e a

, a n d t h e r e b y s e g m e n t l e n g t h

, t o b e a

s i g n i f i c a n t e x p l a n a t o r y v a r i a b l e f o r s e d i m e n t p r o d u c t i o n f r o m f o r e s t r o a d s i n t h e W e s t e r n

S i e r r a s

. W i t h t h e s e s t u d i e s considered

, W E P P : R o a d p r e d i c t i o n s match empirical

research.

2

. 6 Conclusion s

G e n e r a l l y

, d i f f e r e n c e s i n W E P P : R o a d e r o s i o n p r e d i c t i o n s b e t w e e n s o i l t y p e s

a p p e a r t o b e g o v e r n e d b y r e l a t i o n s b e t w e e n s o i l c o h e s i v e s t r e n g t h a n d p a r t i c l e s i z e

. S o i l s

w i t h l o w e r c o h e s i v e s t r e n g t h s can m o r e e a s i l y e n t r a i n e d b y r u n o f f

, b u t a r e p r o n e t o

earlier deposition due to their more massive particle size.41 W E P P : R o a d e r o s i o n p r e d i c t i o n s f o r p a v e d r o a d s e g m e n t s w e r e n o t i n t u i t i v e

.

Further i n v e s t i g a t i o n o f f i e l d c o n d i t i o n o f p a v e d r o a d s e g m e n t d i t c h e s i n p u b l i s h e d

l i t e r a t u r e a n d W E P P : R o a d m o d e l a s s u m p t i o n s a r e n e c e s s a r y t o r e s o l v e t h i s p o t e n t i a l

discrepancy. I n a d d i t i o n

, W E P P : R o a d i s l i m i t e d i n i t s c a p a c i t y t o m o d e l r o a d s i n s o i l s

with greater than 50% rock content.

W E P P : R o a d p r e d i c t i o n s may d e v i a t e a s m u c h a s + /

- 5 0 % f r o m m e a s u r e d v a l u e s

i n t h e f i e l d ( E l l i o t e t a l

. 1 9 9 9 )

. W i t h t h i s f a c t i n m i n d

, t h e o f t e n

- u s e d s l o g a n “ g a r b a g e i n

,

g a r b a g e o u t ” b e c o m e s h i g h l y p e r t i n e n t f o r m a n a g e r s w i s h i n g t o a c h i e v e a c c u r a t e

p r e d i c t i o n s w i t h t h i s m o d e l

. I t i s c r i t i c a l t h a t m a n a g e r s c o l l e c t a c c u r a t e i n p u t d a t a f o r u s e

i n W E P P : R o a d

. A v e r a g i n g v a l u e s o v e r l a r g e a r e a s c o u l d s u b s t a n t i a l l y a l t e r W E P P : R o a d

r e s u l t s

, r e n d e r i n g p r e d i c t i o n s i n v a l i d

. I n d o i n g s o

, v a l u a b l e r e s o u r c e s

- economic,

environmental, or otherwise

- may be wasted.

T h i s s e n s i t i v i t y a n a l y s i s i s n o t a v a l i d a t i o n o f W E P P : R o a d

. R a t h e r

, i t i s m e a n t t o

give further insight into parameter behavior under multiple conditions. Reasons for model

p r e d i c t i o n s f r o m t h e s e t e s t r o a d s e g m e n t s w e r e h y p o t h e s i z e d h e r e b u t

, t o d a t e

, h a v e n o t

all been confirmed by model developers.

The s e n s i t i v i t y a n a l y s i s p r e s e n t e d h e r e p r o v i d e s f u r t h e r b a c k g r o u n d f r o m w h i c h

u s e r s c a n e v a l u a t e W E P P : R o a d e r o s i o n a n d p r e d i c t i o n s

. W i t h t h i s a n a l y s i s

, u s e r s c a n

a l s o c h a n n e l l i m i t e d r e s o u r c e s i n t o c o l l e c t i n g p a r a m e t e r s w h i c h s t a n d t o m o s t a f f e c t t h e

er o s i o n p r e d i c t i o n o f i n t e r e s t ( s e d i m e n t l e a v i n g t h e r o a d v e r s u s s e d i m e n t l e a v i n g t h e

b u f f e r )

. F i n a l l y

, e r o s i o n p r e d i c t i o n d e v i a t i o n f r o m d i r e c t o b s e r v a t i o n c a n b e e v a l u a t e d

through this sensitivity analysis and critical interpretation of model performance

.42 2

. 7 References

A m o r e

, E

. , M o d i c a

, C

. , N e a r i n g

, M

. A

. , a n d S a n t o r o

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. 2 0 0 4

. S c a l e e f f e c t i n U S L E

a n d W E P P a p p l i c a t i o n f o r s o i l e r o s i o n c o m p u t a t i o n f r o m t h r e e S i c i l i a n b a s i n s

. J o u r n a l o f

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B i l b y

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- surface

s e d i m e n t i n f o r e s t e d w a t e r s h e d s i n s o u t h e a s t e r n W a s h i n g t o n

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-

468.

B r a d y

, N

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L o g g i n g R o a d s i n T w o B a s i n s

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32(6): 1195

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. A M ETHODOLOGY FOR PLANNING ROAD BEST MANAGEMENT

PRACTICES COMBIN ING WEPP: ROAD EROSION MODELING AND

SIMULATED ANNEALING OPTIMIZATION

3 .1 Abstract

T o m i n i m i z e e r o s i o n f r o m r o a d s

, m a n a g e r s i n s t a l l a n d m a i n t a i n p h y s i c a l B e s t

M a n a g e m e n t P r a c t i c e s ( B M P s )

. B M P i n s t a l l a t i o n o n a w a t e r s h e d s c a l e i s a d i f f i c u l t t a s k

b e c a u s e o f t h e n e e d t o a c c o u n t f o r m u l t i p l e c o n s t r a i n t s

, s u c h a s a v a i l a b l e b u d g e t

, B M P

m a i n t e n a n c e

, a n d e q u i p m e n t s c h e d u l i n g

. A m e t h o d o l o g y f o r a d d r e s s i n g t h i s c h a l l e n g e is

p r e s e n t e d h e r e t h a t c o m b i n e s W E P P : R o a d e r o s i o n m o d e l i n g a n d s i m u l a t e d a nnealing

o p t i m i z a t i o n

. F i e l d s u r v e y s o f f o r e s t r o a d s a t G l e n b r o o k C r e e k

, N V p r o v i d e d i n p u t s f o r

W E P P : R o a d a n d s u b s e q u e n t i d e n t i f i c a t i o n o f e r o s i o n r i s k p o t e n t i a l

. A p p r o p r i a t e B M P s

w e r e i d e n t i f i e d f o r s e g m e n t s p o s i n g a n e r o s i o n r i s k

. T h e s e B M P s

, a s s o c i a t e d s e d i m e n t

,

c o s t s

, a n d m a i n t e n a n c e f r e q u e n c i e s w e r e i n p u t i n t o a mo d e l u s i n g s i m u l a t e d a n n e a l i n g a s

a h e u r i s t i c s e a r c h b a c k b o n e

. T h e a l g o r i t h m m i n i m i z e d s e d i m e n t l e a v i n g t h e r o a d b u f f e r

o v e r t h e c o u r s e o f t h e p l a n n i n g h o r i z o n b y c o m p a r i n g p o t e n t i a l B M P i n s t a l l a t i o n a n d

m a i n t e n a n c e s c e n a r i o s

. P r e e x i s t i n g B M P m a i n t e n a n c e c o s t s

, n e w B M P i n s t a l l a t i o n c o s t s

a n d m a i n t e n a n c e r e g i m e n s

, a n d e q u i p m e n t s c h e d u l i n g c o n s i d e r a t i o n s we r e a c c o u n t e d f o r

w i t h i n t h e a l g o r i t h m

. T h r e e s c e n a r i o s a t m u l t i p l e i n i t i a l b u d g e t l e v e l s w e r e m o d e l e d t o

demonstrate the utility of this methodology.

O f t h e 1 7 3 s u r v e y e d s e g m e n t s

, 3 8 segments w e r e a v a i l a b l e t o h a v e BMPs

installed

. T h e b e s t p o s s i b l e s o l u t i o n y i e l d e d a r e d u c t i o n i n s e d i m e n t l e a v i n g t h e b u f f e r

o v e r t h e c o u r s e o f t h e p l a n n i n g h o r i z o n b y 7 0%. T h i s m e t h o d o l o g y c a n b e a p p l i e d t o a n y

watershed, but relies heavily on the perceived accuracy of road erosion predictions

.46 3 .2 Introduction

F o r e s t r o a d s

, w h e n i m p o s e d o n t h e l a n d s c a p e

, o f t e n b e c o m e t h e m o s t p r o m i n e n t

s o u r c e o f e r o s i o n i n m o u n t a i n o u s w a t e r s h e d s ( B u r r o u g h s 1 9 9 0 )

. R o a d s c a n m a g n i f y

e r o s i o n r a t e s b y m u l t i p l e o r d e r s o f m a g n i t u d e ( e

. g

. M e g a h a n a n d K e t c h e s o n 1 9 9 6

,

M e g a h a n a n d K i d d 1 9 7 2 )

. F r e q u e n t l y

, r o a d s i n c r e a s e s e d i m e n t d e l i v e r y t o s t r e a m s i n a

g i v e n w a t e r s h e d a n d a l t e r g e o m o r p h i c p r o c e s s e s b o t h i n a n d o u t o f t h e s t r e a m c h a n n e l

( e

. g

. M o n t g o m e r y 1 9 9 4

, J o n e s e t a l

. 2 0 0 0

, W e m p l e e t a l

. 1 9 9 6 )

. I m p a c t s o f r o a d

-

g e n e r a t e d f i n e s e d i m e n t e n t e r i n g s t r e a m s i n c l u d e i n c r e a s e d t u r b i d i t y ( F o r m a n a n d

A l e x a n d e r 1 9 9 8 ) a n d i m p a i r m e n t o f f i s h h a b i t a t ( F P A C 2 0 0 0 )

. R o a d s b e c o m e a c h r o n i c

source of fine sediment to downstream water bodies (Luce 2002).

I t c o u l d b e a r g u e d t h a t f e w p l a c e s i n t h e w estern Uni t e d S t a t e s a r e a s a w a r e o f t h e

downstream consequences o f u p s t r e a m management a c t i o n s a s t h e L a k e T a h o e B a s i n

.

L a k e T a h o e h a s b e e n d e c l a r e d a n O u t s t a n d i n g N a t u r a l R e s o u r c e W a t e r b y t h e U

. S

.

E n v i r o n m e n t a l P r o t e c t i o n A g e n c y

. A s a r e s u l t o f p r e c i p i t o u s l o s s e s i n w a t e r c l a r i t y o v e r

t h e p a s t 2 5 y e a r s

, L a k e T a h o e i s c u r r e n t l y d e s i g n a t e d a s a n i m p a i r e d w a t e r b o d y u n d e r

S e c t i o n 3 0 3 ( d ) o f t h e C l e a n W a t e r A c t ( R o b e r t s a n d R e u t e r 2007)

. I n o r d e r t o s t e m t h i s

d e c l i n e i n w a t e r c l a r i t y

, i t i s i m p e r a t i v e t h a t i n n o v a t i v e s o l u t i o n s f o r m i t i g a t i n g f i n e

sediment inputs to Lake Tahoe be conceived.

T o m i n i m i z e r o a d e r o s i o n

, m a n a g e r s f r e q u e n t l y i m p l e m e n t B e s t M a n a g e m e n t

Practices (BMPs). In practice, physical BMPs (e.g. drain dips, cross

- draining culverts, rip

r a p ) a r e i n s t a l l e d b a s e d o n p r o f e s s i o n a l j u d g m e n t i n t h e f i e l d

. O f t e n

, n o d a t a o n s e d i m e n t

leaving the road surface or sediment leaving the buffer (that portion of the hill slope lying

b e t w e e n t h e f i l l s l o p e a n d t h e n e a r e s t w a t e r w a y ) i s u s e d t o g u i d e j u d g m e n t

. O n e w a y t o47 mi t i g a t e t h i s i s s u e i s t o a p p l y a r o a d e r o s i o n m o d e l s u c h a s W E P P : R o a d ( E l l i o t e t a l

.

1 9 9 9 )

. W E P P : R o a d p r o v i d e s a u s e r

- f r i e n d l y p r o c e s s

- b a s e d m o d e l v i a w e b i n t e r f a c e f o r

managers to evaluate erosion from forest roads.

W h i l e W E P P : R o a d p r o v i d e s a h i g h l y c o st

- e f f e c t i v e m e a n s o f e v a l u a t i n g r o a d

e r o s i o n u s i n g r e l a t i v e l y f e w m e a s u r e m e n t s m a d e i n t h e f i e l d

, n e w B M P i m p l e m e n t a t i o n

o n a w a t e r s h e d s c a l e i s a d a u n t i n g t a s k

. G i v e n b u d g e t c o n s t r a i n t s

, m a n a g e r s m u s t

evaluate which sites stand to benefit most from BMP i mplementation right now as well as

p l a n n i n g f u t u r e B M P i m p l e m e n t a t i o n

. I n a d d i t i o n

, e x i s t i n g B M P s m u s t b e m a i n t a i n e d t o

e n s u r e c o n t i n u e d e f f e c t i v e n e s s

, a l o n g w i t h a n y n e w B M P s

. F u r t h e r c o m p l i c a t i o n s arise

f r o m t h e l o g i s t i c s a s s o c i a t e d w i t h p r o j e c t p l a n n i n g f o r B M P i n s t a l l a t i o n b e c a u s e i t w o u l d

be cheaper to install and maintain BMPs in near proximity in the same time period.

H e r e

, a s o l u t i o n t o t h i s p r o b l e m i s p r e s e n t e d t h a t c o m b i n e s W E P P : R o a d

- d erived

e r o s i o n d a t a w i t h s i m u l a t e d a nnealing optimization to s p a t i a l l y o p t i m i z e B M P p l a c e m e n t

a c r o s s t h e r o a d n e t w o r k

. I n d o i n g s o

, this methodology minimizes road

- r e l a t e d s e d i m e n t

e n t e r i n g s t r e a m s i n a g i v e n w a t e r s h e d w h i l e t a k i n g i n t o a c c o u n t b u d g e t c o n s t r a i n t s a n d

spatial adjacency considerations over the course of a planning horizon.

3 .3 Study Site

L a k e T a h o e

, o n t h e C a l i f o r n i a

- N e v a d a b o r d e r

, lies b e t w e e n t h e S i e r r a N e v a d a

Range to the west and the Carson Range to the east. Elevations range from approximately

6 9 0 0 f e e t t o n e a r l y 1 1

, 0 0 0 f e e t

. A v e r a g e m a x i m u m a i r t e m p e r a t u r e f r o m 1 9 1 5

- 1 9 9 8 w a s

5 6 d e g r e e s F a n d a v e r a g e m i n i m u m t e m p e r a t u r e w a s 3 0 d e g r e e s F

. P r e c i p i t a t i o n i n t h e48 basin ranges from 70 to 90 inches per year on the west side of the basin to 30 to 40 inches

on the east side, with most precipitation falling as snow (Rowe et al. 2002)

.

Figure 1 0 . Map of study area

.

T h e G l e n b r o o k C r e e k w a t e r s h e d e n c o m p a s s e d t h e m a j o r i t y o f t h e s t u d y a r e a

( F i g u r e 1 0 ). G l e n b r o o k C r e e k i s c l o s e t o C a r s o n C i t y

, N V

, m a k i n g i t a n i m p o r t a n t

r e c r e a t i o n a c c e s s p o i n t f o r t h e L a k e T a h o e B a s i n

. I n a d d i t i o n

, t h e R o c k y M o u n t a i n

R e s e a r c h S t a t i o n i s p a r a m e t e r i z i n g W E P P : R o a d u s i n g r a i n f a l l s i m u l a t i o n d a t a f r o m

G l e n b r o o k C r e e k

. W i t h t h e s e f a c t o r s i n m i n d

, G l e n b r o o k C r e e k w a s d e e m e d a n

appropriate watershed for this stu dy.49 Glenbrook Creek, on the east side of the L ake T ahoe B asin , lies approximately 15

m i l e s w e s t o f C a r s o n C i t y

, N V a n d 2 0 m i l e s n o r t h o f S o u t h L a k e T a h o e

, C A

. T h e

w a t e r s h e d r a n g e s i n e l e v a t i o n f r o m a p p r o x i m a t e l y 6 2 0 0 f e e t t o 8 8 0 0 f e e t a t i t s f u r t h e s t

upsl o p e e x t e n t

. S o i l s a r e primarily g r a n i t i c i n o r i g i n ( G r i s m e r a n d H o g a n 2 0 0 4 )

. Average

a n n u a l p r e c i p i t a t i o n a t t h e T A H O E C A S N O T E L s i t e

, w h i c h l i e s a t l a k e e l e v a t i o n 1 2

m i l e s n o r t h w e s t of a n d a c r o s s t h e l a k e f r o m G l e n b r o o k C r e e k

, is approximately 31

inches.

A g a t e d h o u s i n g d e v e l o p m e n t n e a r t h e m o u t h o f G l e n b r o o k C r e e k w a s e x c l u d e d

f r o m t h e s t u d y a r e a

. T h e p o r t i o n o f F o r e s t R o a d 1 4 N 3 2 c o n n e c t i n g w i t h H i g h w a y 5 0 a t

S p o o n e r S u m m i t w a s i n c l u d e d i n t h e s t u d y a r e a s i n c e i t s e r v e d a s a m a j o r a c c e s s p o i n t t o

t h e w a t e r s h e d

. T h e g a t e d r o a d s e g m e n t t o t h e w e s t o f H i g h w a y 5 0

, k n o w n a s t h e “ O l d

L i n c o l n H i g h w a y

, ” w a s i n i t i a l l y s u r v e y e d u s i n g G P S b u t n e v e r m o d e l e d f o r r o a d e r o s i o n

since it was only used for administrative access.

3 .4 Methods

3 .4a Field data c ollection:

F i e l d d a t a c o l l e c t i o n w a s c o n d u c t e d i n J u l y 2 0 0 8

. O f t h e 7

. 6 m i l e s o f r o a d

s u r v e y e d ( 5

. 6 m i l e s o f t h o s e r o a d s b e i n g i n t h e L ake T ahoe B a s i n )

, 1 7 3 hydraulically

c o n t i g u o u s r o a d s e g m e n t s w e r e i d e n t i f i e d

. W E P P : R o a d i n p u t p a r a m e t e r s d e t e r m i n e d o r

measured in the field for each of these segments included:

- Identification of road segment “ from ” nodes and “ to ” nodes

- GPS coordinates for “ from ” and “ to ” nodes

- Road gradient50 - Road surface type

- Coarse rock content

- Fillslope gradient

- Fillslope length

- Soil texture

- Road width

- Road design (insloped or outsloped, rutted or unrutted, bare or vegetated ditch)

“ From ” n o d e s a n d “ to ” n o d e s w e r e i d e n t i f i e d f o r e a c h r o a d s e g m e n t

. “ To ” nodes

w e r e a l w a y s d e l i v e r y p o i n t s

, o r t h e p e r c e i v e d s e g m e n t o u t l e t f o r r u n o f f a n d s e d i m e n t

.

“ From ” n o d e s c o m p r i s e d t h e e n t r a n c e o r b e g i n n i n g s e g m e n t l o c a t i o n s f o r r u n o f f a n d

s e d i m e n t e n t r a i n m e n t

. S e g m e n t s w e r e d e l i n e a t e d b e t w e e n t w o e x i s t i n g d r a i n a g e

s t r u c t u r e s

, f r o m a s l o p e b r e a k o r h i g h p o i n t t o a d r a i n a g e s t r u c t u r e

, f r o m a h i g h p o i n t t o a

low point , or between a drainage structure and a low point.

G P S p o i n t s w e r e t a k e n u s i n g a G P S f l a s h c a r d a d a p t e r f o r a D e l l A x i m P e r s o n a l

Digital Assistant. Road gradient and fillslope gradient were both manually measured with

a c l i n o m e t e r

. W i d t h s a n d l e n g t h s w e r e a l l t a k e n u s i n g a l o g g e r ’ s t a p e d e l i n e a t e d i n t e n t h s

o f f e e t

. W h e n n e c e s s a r y

, s l o p e a n d l e n g t h / w i d t h m e a s u r e m e n t s w e r e a v e r a g e d o v e r t h e

l e n g t h o f t h e s e g m e n t

. C o a r s e r o c k c o n t e n t a n d s o i l t e x t u r e w e r e b o t h p e r f o r m e d o n s o i l

a d j a c e n t t o t h e r o a d g r a d e i t s e l f

. C o a r s e r o c k c o n t e n t w a s e s t a b l i s h e d u s i n g a 2 m m s i e v e

b y t a k i n g a r a t i o b e t w e e n t o t a l s o i l v o l u m e a n d r o c k v o l u m e g r e a t e r t h a n 2 m m d i a meter

.

S o i l t e x t u r e w a s e v a l u a t e d u s i n g t h e h a n d

- t e x t u r i n g p r o c e d u r e d e v e l o p e d b y T h e i n

(1979).51 3 .4b Data acquisit ion using GIS/preparation for model input :

F o r G I S

- d e r i v e d i n p u t p a r a m e t e r s

, v e c t o r d a t a w a s p r o v i d e d b y t h e T a h o e

R e g i o n a l P l a n n i n g A g e n c y ( T R P A ) a n d t h e 1 0 m D i g i t a l E l e v a t i o n M o d e l ( D E M ) w a s

obtained from the Lake Tahoe GIS Data Clearinghouse ( http://ta hoe.usgs.gov/ )

.

W E P P : R o a d p a r a m e t e r s d e r i v e d f r o m G I S d a t a o r f r o m L a k e T a h o e B a s i n

M a n a g e m e n t U n i t ( L T B M U ) d a t a i n c l u d e d s e g m e n t l e n g t h

, b u f f e r s l o p e

, b u f f e r l e n g t h

,

a n d r o a d t r a f f i c l e v e l

. S e g m e n t l e n g t h w a s f o u n d b y f i r s t r e p r o c e s s i n g t h e G P S

- derived

r o a d l a y e r i n t o s e g m e n t s b a s e d o n h y d r a u l i c c o n n e c t i v i t y o b s e r v e d o n t h e g r o u n d

, t h e n

using a GIS to calculate the length of those segments.

D e l i v e r y p o i n t s f o r i n s l o p e d s e g m e n t s w e r e a l w a y s a s s u m e d t o b e “ to ” nodes.

S i n c e s e d i m e n t d e l i v e r y f r o m o u t s l o p e d s e g m e n t s o c c u r s a l o n g t h e e n t i r e l e n g t h o f t h e

se g m e n t

, d e l i v e r y p o i n t s f o r t h e s e s e g m e n t s w e r e d e s i g n a t e d a t t h e m i d d l e o f t h e

s e g m e n t

. B u f f e r l e n g t h a n d s l o p e f o r e a c h s e g m e n t w e r e c a l c u l a t e d f r o m t h e s e d e l i v e r y

p o i n t s

. S i n c e W E P P : R o a d w i l l n o t a c c e p t s l o p e s e x c e e d i n g 1 0 0 % a n d r o a d l e n g t h s

e x c e e d i n g 1 0 0 0 f e e t

, v a l u e s e x c e e d i n g t h e s e t h r e s h o l d s w e r e r e p l a c e d w i t h 9 9 a n d 9 9 9

,

r e s p e c t i v e l y

. I n l o c a t i o n s w h e r e t h e r e w a s n o f i l l s l o p e

, W E P P d e f a u l t s o f

. 3 % s l o p e a n d

one foot were used.

Buffer slope and buf fer length were found using a software program developed by

t h e F o r e s t O p e r a t i o n s R e s e a r c h a n d M a n a g e m e n t S c i e n c e s G r o u p a t T h e U n i v e r s i t y o f

Montana. Using road network delivery points, a raster stream layer, and a flow path raster

d e r i v e d f r o m a D E M

, t h i s p r o g r a m c a l c u l a t e d b u f f e r l e n g t h a s t o t a l flow path distance to

t h e n e a r e s t s t r e a m

. B u f f e r s l o p e w a s c a l c u l a t e d f o r e a c h r o a d s e g m e n t using this flow

path distance.52 R o a d s e g m e n t s w e r e p r o c e s s e d i n W E P P : R o a d B a t c h a c c o r d i n g t o s o i l t e x t u r e

.

S a n d y c l a y l o a m a n d s i l t y c l a y l o a m w e r e g r o u p e d t o g e t h e r a n d p r o c e s s e d a s b e i n g “ c l a y

l o a m ” s o i l t y p e ( H

. Rhee p e r s o n a l c o m m u n i c a t i o n )

. “ T A H O E C A ” w a s c h o s e n f o r t h e

c l i m a t e

, b e i n g t h e c l o s e s t a v a i l a b l e c l i m a t e b a s e s t a t i o n w i t h i n t h e W E P P : R o a d c l i m a t e

library

. B a s e d o n e l e v a t i o n a t a c e n t r a l l o c a t i o n i n t h e w a t e r s h e d

, m o n t h l y p r e c i p i t a t i o n

v a l u e s w e r e i n c r e a s e d b a s e d o n t h e P R I S M m o d e l ( a c c e s s i b l e t h r o u g h t h e W E P P : R o a d

interface)

. S i n c e c l i m a t e d a t a s t o r e d f o r u s e w i t h t h e F S W E P P i n t e r f a c e s i n c l u d e only

month l y v a l u e s

, W E P P : R o a d u s e s t h e C L I G E N w e a t h e r g e n e r a t o r t o produce daily

c l i m a t e d a t a f o r t h e d e s i r e d s i m u l a t i o n t i m e ( E l l i o t e t a l

. 1 9 9 9 )

. Thirty y e a r s o f d a i l y

c l i m a t e d a t a w e r e generated f o r t h e s e s i m u l a t i o n s

. R o a d t r a f f i c l e v e l w a s h e l d c o n s t a n t a t

“lo w” for all segments (Briebart et al. 2006)

.

A s e n s i t i v i t y a n a l y s i s o f W E P P : R o a d ( C h a p t e r 2 ) a n d c u r r e n t l i t e r a t u r e s u g g e s t

t h a t r o a d l e n g t h a n d w i d t h

, r o a d g r a d i e n t

, s o i l t y p e

, a n d s u r f a c e t y p e a l l s e r v e a s

i m p o r t a n t c o n t r o l s o n s e d i m e n t l e a v i n g t h e r o a d

. T h o s e s a m e f a c t o r s

, c o u p l e d w i t h b u f f e r

g r a d i e n t a n d l e n g t h

, c o n t r o l s e d i m e n t l e a v i n g t h e b u f f e r

. T o e x p l o r e t h e l i n k a g e b e t w e e n

t h e s e f a c t o r s a n d W E P P : R o a d p r e d i c t i o n s i n G l e n b r o o k C r e e k

, r e l a t i o n s h i p s b e t w e e n

e r o s i o n r a t e ( w h i c h n o r m a l i z e s e r o s i o n v a l u e s a c r o s s s e g m e n t s o f a l l l e n g t h s a n d w i d t h s )

a n d t h e s e p a r a m e t e r s w e r e e v a l u a t e d along w i t h a b s o l u t e p r e d i c t i o n v a l u e s f o r G l e n b r o o k

Creek

. W h e r e n e c e s s a r y

, e r o s i o n r a t e s w e r e c a l c u l a t e d u s i n g a v e r a g e s u r f a c e a r e a s ; t o t a l

r o a d l e n g t h w i t h i n a s u r f a c e o r s o i l t y p e w a s m u l t i p l i e d b y a v e r a g e r o a d w i d t h f o r t h a t

soil or surface type.53 3 .4c “Hot spot” identification and verification :

F o l l o w i n g W E P P : R o a d B a t c h p r o c e s s i n g

, r e s u l t s w e r e r e v i e w e d t o i d e n t i f y

which segments had the greatest amount of sediment leaving the buffer . Natural breaks in

a h i s t o g r a m w e r e u s e d t o d e t e r m i n e “ h o t s p o t s ”

, o r t h o s e s e g m e n t s t h a t w e r e c o n t r i b u t i n g

large a m o u n t s o f s e d i m e n t t o G l e n b r o o k ’ s s t r e a m s

. T h o s e s e g m e n t s t h a t w e r e n o t

c l a s s i f i e d a s h i g h r i s k s e g m e n t s w e r e c l a s s i f i e d a s m o d e r a t e o r l o w r i s k s e g m e n t s

. T h e

L T B M U s u p p o r t e d o u r r i s k r a t i n g c r i t e r i a ( C

. S h o e n p e r s o n a l c o m m u n i c a t i o n )

. T he

breakdown is sh own in Table 4

.

F i e l d v e r i f i c a t i o n o f t h e h i g h r i s k r o a d s e g m e n t s w i t h i n t h e G l e n b r o o k W a t e r s h e d

w a s c o n d u c t e d i n S e p t e m b e r 2 0 0 8

. A L T B M U r o a d s e n g i n e e r a c c o m p a n i e d u s d u r i n g

f i e l d v e r i f i c a t i o n

. D u r i n g t h i s p r o c e s s

, w e a s s e s s e d t h e l e g i t i m a c y o f e a c h hot s p o t b y

i d e n t i f y i n g t h e o v e r r i d i n g c h a r a c t e r i s t i c c a u s i n g t h e s e g m e n t t o b e a n e r o s i o n risk.

S e g m e n t s w e r e d e e m e d l e g i t i m a t e h o t s p o t s f o r r e a s o n s r a n g i n g f r o m s t e e p n e s s o f t h e

s e g m e n t t o l e n g t h o f s e g m e n t t o l a c k o f s u r f a c e d u r a b i l i t y

. I n a d d i t i o n t o v a l i dating

e r o s i o n r i s k f r o m m o d e l e d r o a d s e g m e n t s

, a p p l i c a b l e t r e a t m e n t s w e r e a s s i g n e d t o t h e

road segments visited.

Table 4

. C l a s s i f i c a t i o n o f r o a d s e g m e n t s w i t h g r e a t e r t h a n 0 l b s / y r s e d i m e n t l e a v i n g b u f f e r i n t o r i s k r a t i n g

classes.

Risk rating Number of

segments in

class Low bound

(lbs/yr

sediment

leaving

buffer) High

bound

(lbs/yr

sediment

leaving

buffer) Miles of

road in risk

class Percent of

total road

mileage

surveyed

High risk 9 13 0 1 300 0.9 12

Moderate

risk 30 12 13 0 1. 5 19

Low risk 35 1 11 1. 8 2154 3 .4d Simulated annealing modeling f ramework:

Simulated a nnealing , developed by Kirkpatrick and others (1983) , uses a modified

M o n t e C a r l o s i m u l a t i o n t h a t l o o s e l y r e s e m b l e s m e t a l c o o l i n g a f t e r l e a v i n g a f o r g e

. This

o p t i m i z a t i o n t e c h n i q u e s o l v e s p r o b l e m s t h r o u g h c o m p a r i s o n o f n e i g h b o r h o o d s o l u t i o n s

.

A n i n t e g r a l c o m p o n e n t o f t h e a l g o r i t h m i s i t s l i n k a g e t o t e m p e r a t u r e ; i n i t i a l a n d f i n a l

t e m p e r a t u r e s

, a l o n g w i t h a c o o l i n g r a t e

, a r e d e f i n e d w i t h i n t h e a l g o r i t h m

. Acceptance

p r o b a b i l i t i e s

, a l s o l i n k e d t o t e m p e r a t u r e

, p r o v i d e f o r t h e p o s s i b i l i t y o f a c c e p t i n g w o r s e

s o l u t i o n s d u r i n g i t e r a t i v e s o l u t i o n c o m p a r i s o n

. A f l o w c h a r t e x p l a i n i n g t h e a d a p ted

simulated a nnealing algorithm framework to this planning problem is in Appendix B

.

T h e o b j e c t i v e f u n c t i o n o f t h i s o p t i m i z a t i o n p r o b l e m w a s t o m i n i m i z e s e d i m e n t

leaving the buffer through the course of the planning horizon [Eq. 1] while accounting for

budget as a constraint [Eq. 2].

Minimize

, ( 1 )

Subject to

,

= 1

where

Z : total sediment leaving the buffer through the course of the planning horizon

j : planning period

H : length of planning horizon

i: segment number

N: total number of segments on the road network

, sediment leaving the buffer from segment i during planning period j55 , : cost of BMP treatment scheduled for segment i in planning period j

: budget for planning period j

( ) : discount term

S e d i m e n t w a s m i n i m i z e d b y a p p l y i n g a p p r o p r i a t e B M P s t o t r e a t a b l e r o a d

s e g m e n t s

. A p p r o p r i a t e B M P s w e r e p r i o r i t i z e d b a s e d o n e x i s t i n g c o n d i t i o n o f t h e r o a d

network ( T a b l e 5 )

. T h e s e p r i o r i t i e s w e r e e s t a b l i s h e d t h r o u g h a f i e l d v i s i t w i t h L T B M U

r o a d s e n g i n e e r s a s w e l l a s p e r s o n a l c o m m u n i c a t i o n w i t h o t h e r USFS r o a d s e n g i n e e r s

. O f

the 74 road segments producing greater than zero sediment leaving the buffer per year, 38

co u l d b e a s s i g n e d t r e a t m e n t s

. 3 6 s e g m e n t s c o u l d n o t b e a s s i g n e d B M P s b e c a u s e t h e y

w e r e e i t h e r p a v e d ( a s s u m e d t o b e a n “ e n d

- p o i n t ” B M P ) o r h a d s o m e c o m b i n a t i o n o f

c o n d i t i o n s w h i c h p r e v e n t e d a s s i g n m e n t o f B M P t r e a t m e n t s

. F o r e x a m p l e

, o u t s l o p i n g w a s

n o t c o n s i d e r e d a n a p p r o p r i a t e B M P f o r g r a v e l e d s e g m e n t s a n d d r a i n d i p s w e r e n o t

applied to segments already outsloped.

W i t h i n t h e a l g o r i t h m

, a n i n i t i a l b u d g e t p e r p e r i o d w a s s p e c i f i e d

. T h i s i n i t i a l

b u d g e t w a s t h e m a x i m u m t h a t c o u l d b e s p e n t o n B M P i n s t a l l a t i o n a n d m a i n t e n a n c e i n a

g i v e n p l a n n i n g p e r i o d

. P l a n n i n g h o r i z o n w a s s p e c i f i e d a s 2 0 y e a r s

, w i t h p l a n n i n g p e r i o d

being one year.

Each segment had four possible BMP treatment options availab le, with one option

being “none ”

, or no BMP assigned to the segment. Only one option per segment could be

s e l e c t e d f o r i m p l e m e n t a t i o n b y t h e a l g o r i t h m

. I f g r e a t e r t h a n f o u r o p t i o n s w e r e p o s s i b l e

o n a g i v e n r o a d s e g m e n t

, t h e t h r e e o p t i o n s ( b e s i d e s n o n e ) t h a t p r o d u c e d t h e g r e a t e s t

reduction i n s e d i m e n t l e a v i n g t h e r o a d b u f f e r w e r e u s e d

. F u r t h e r c r i t e r i a u s e d t o a s s i g n

BMPs on the r oad network are shown in Table 6

.56 Table 5 . Priority of BMP assignment for a given road segment

Condition Priority 1 Priority 2 Priority 3

Buffer slope > fill

slope Outslope Drain dips Pave

Road Slope > 17% Pave Drain dips Outslope

Note: Drain dips applicable on any segment greater than 150 feet in length.

Table 6 . Further criteria used when assigning BMPs to problematic road segments.

BMP Comment

Outslope Delivery point reassigned to center of road segment. Not

applicable on paved or graveled segments.

Pave If paving is already installed on a segment, no further BMPs

can be installed.

Drain dips Segment length iteratively divided in half until segment

length is less than 150 feet or sediment leaving buffer is zero.

Drain dips not applicable on outsloped segments.

In the case of drain dips, multiple options could be assigned. On segments longer

than 150 feet, segments were divided in half to represent a hydrologic break between the

two segments. These segments were iteratively divided in half until segment length wa s

less than 150 feet or sediment leaving the buffer equaled zero.

I n s t a l l a t i o n c o s t s

, m a i n t e n a n c e c o s t s

, a n d m a i n t e n a n c e f r e q u e n c i e s a s s o c i a t e d

w i t h a g i v e n B M P a s s i g n m e n t c a n b e f o u n d i n T a b l e 7

. F o r e a c h p o t e n t i a l B M P s c e n a r i o

o n a g i v e n s e g m e n t

, W E P P : R o a d w a s u s e d t o p r e d i c t s e d i m e n t l e a v i n g t h e b u f f e r

. These

predictions

, a l o n g w i t h t h e c o s t s a n d m a i n t e n a n c e f r e q u e n c i e s a s s o c i a t e d w i t h e a c h B M P

s c e n a r i o

, w e r e f o r m a t t e d i n t o a n i n p u t t a b l e f o r t h e BMP

- S A a l g o r i t h m

. S e e A p p e n d i x C

for an example BMP

- SA i nput table.57 T a b l e 7

. I n s t a l l a t i o n c o s t s

, m a i n t e n a n c e c o s t s

, a n d m a i n t e n a n c e f r e q u e n c i e s a s s o c i a t e d w i t h a s s i g n e d

BMPs

. These costs were compiled through a combination of personal communication with USFS personnel

and the USFS Region 4 Cost Estimating Guide for Road Construction (USDA 2008).

BMP Installation

cost ($) Equipment

move

- in

costs

($) Maintenance

cost ($) Equipment

move

- in costs

for

maintenance

($) Maintenance

frequency

(yrs)

Outsloping 3000/mile 1000 1000/mile 500 3

Drain dips 100/each 500 100/each 500 5

Pavement 245000/mile 1500 15000/mile 500 7

A p p l i c a b l e B M P i n s t a l l a t i o n a n d m a i n t e n a n c e s c e n a r i o s w e r e c r e a t e d f r o m t h i s

l i s t o f B M P o p t i o n s

. B M P

- S A f i r s t r a n d o m l y a s s e m b l e d a n i n i t i a l

, o r c u r r e n t

, s o l u t i o n

w h e r e o n e t r e a t m e n t o p t i o n w a s s e l e c t e d f o r e v e r y s e g m e n t

. A n e i g h b o r h o o d s o l u t i o n

w a s t h e n f o r m u l a t e d w h e r e o n e e l e m e n t o f t h e c u r r e n t s o l u t i o n w a s a l t e r e d ( F i g u r e s 1 1

-

13 )

. S e d i m e n t g e n e r a t e d f r o m t h e s e a l t e r n a t i v e s o l u t i o n s w a s c o m p a r e d w i t h i n t h e

algor i t h m a s t e m p e r a t u r e w a s c o o l e d

. I f t h e n e i g h b o r h o o d s o l u t i o n w a s b e t t e r t h a n t h e

c u r r e n t s o l u t i o n

, t h e c u r r e n t s o l u t i o n w a s a l w a y s a c c e p t e d a n d u s e d t o f o r m u l a t e t h e n e x t

n e i g h b o r h o o d s o l u t i o n f o r c o m p a r i s o n

. I f a n e i g h b o r h o o d s o l u t i o n w a s w o r s e t h a n t h e

c u r r e n t s o l u t i o n

, a n a c c e p t a n c e p r o b a b i l i t y w a s c a l c u l a t e d t h a t w a s l i n k e d t o t h e

temperature at the time of comparison using the following equation :58 D e p e n d i n g o n t h e a c c e p t a n c e p r o b a b i l i t y

, t h e n e i g h b o r h o o d s o l u t i o n c o u l d b e

a c c e p t e d a s t h e c u r r e n t s o l u t i o n d e s p i t e p r o d u c i n g m o r e s e d i m e n t t h a n t h e p r e v i o u s

s o l u t i o n o v e r t h e c o u r s e o f t h e p l a n n i n g h o r i z o n

. W i t h t h i s i t e r a t i v e c o m p a r i s o n o f

s o l u t i o n s

, a n e a r

- o p t i m u m B M P i n s t a l l a t i o n a n d m a i n t e n a n c e s c e n a r i o w a s f o r m u lated

upon reaching the stopping conditions dictated within the algorithm.

T o a c c o u n t f o r e q u i p m e n t s c h e d u l i n g o n a d j a c e n t r o a d s e g m e n t s

, c l u s t e r s o f

s e g m e n t s w e r e c r e a t e d

. R o a d s e g m e n t s w i t h d e l i v e r y p o i n t s w i t h i n 1 0 0 0 f e e t o f e a c h

o t h e r w e r e g r o u p e d i n t o a s i n g l e c l u s t e r b o t h m a n u a l l y a n d u s i n g a s u b r o u t i n e w i t h i n t h e

BMP

- S A a l g o r i t h m

. F o r r o a d w o r k c o n d u c t e d i n t h e L a k e T a h o e B a s i n

, i t c o s t s $ 5 0 0 f o r

e a c h p i e c e o f e q u i p m e n t t h a t m u s t b e m o v e d i n t o t h e b a s i n ( P

. P o t t s p e r s o n a l

c o m m u n i c a t i o n )

. I t w a s a s s u m e d t h a t t h e s a m e p i e c e o f e q u i p m e n t c o u l d b e u s e d f o r

m a i n t e n a n c e a n d i n s t a l l a t i o n o f a l l B M P s o f t h e s a m e t y p e w i t h i n a c l u s t e r

. T h u s

,

e q u i p m e n t m o v e

- i n c o s t s w e r e i n c u r r e d o n l y o n c e w i t h i n e a c h c l u s t e r

. I n a c c o u n t i n g f o r

t h e s e c o s t s

, a s s u m p t i o n s w e r e m a d e a s t o h o w m a n y p i e c e s o f e q u i p m e n t w e r e r e q u i r e d

to install each BMP.

W h i l e c o m p u t i n g t h e o b j e c t i v e f u n c t i o n

, B M P

- S A d i s c o u n t e d s e d i m e n t l e a v i n g

t h e b u f f e r b y f o u r p e r c e n t p e r y e a r

. D i s c o u n t i n g b y f o u r p e r c e n t i s s t a n d a r d p r a c t i c e i n

n a t u r a l r e s o u r c e s e c o n o m i c a n a l y s i s i n v o l v i n g U

. S

. F o r e s t S e r v i c e i n v e s t m e n t s ( R o w e t

al. 1981).59 BMP Segment Period Sediment

leaving buffer

(tons)

Outslope 10 2 .01 0

Drain dip 27 4 .002

Pavement 13 8 .035

Figure 1 1 . Example initial solution formulated from a list of alternative BMPs on a road segment. Initial solutions are randomly formulated within BMP

- SA.

BMP Segment Period Sediment leaving

buffer (tons)

Outslope 10 2 .01 0

Drain dip 27 

## 12 .002

Pavement 13 8 .035

F i g u r e s 1 2 a n d 1 3

. E x a m p l e s o f n e i g h b o r h o o d s o l u t i o n s f o r m u l a t e d f r o m the i n i t i a l ( c u r r e n t ) s o l u t i o n

. N e i g h b o r h o o d s o l u t i o n s a r e f o r m u l a t e d b y c h a n g i n g o n e

e l e m e n t o f t h e i n i t i a l ( c u r r e n t ) s o l u t i o n

, e i t h e r p e r i o d o f i n s t a l l a t i o n ( F i g u r e 1 2 ) o r B M P i n s t a l l e d ( F i g u r e 1 3 )

. I n t h i s c a s e

, t h e B M P t h a t w a s i n s t a l l e d o r t h e t y p e

of BMP installed can be changed. With BMP

- SA, current and neighborhood BMP solutions are iteratively compared. The algorithm compares two solutions, and

i f a n e i g h b o r h o o d s o l u t i o n i s w o r s e t h a n t h e c u r r e n t s o l u t i o n

, a n a c c e p t a n c e p r o b a b i l i t y i s c a l c u l a t e d s u c h t h a t

, b a s e d o n t e m p e r a t u r e

, t h e n e i g h b o r h o o d s o l u t i o n

m a y b e a c c e p t e d a s t h e c u r r e n t s o l u t i o n

. I n d o i n g s o

, B M P

- S A c a n a r r i v e a t a c o n s i s t e n t n e a r

- o p t i m u m B M P i m p l e m e n t a t i o n a n d m a n a g e m e n t s c e n a r i o m o r e

quickly than if purely random search techniques were employed. BMP Segment Period Sediment

leaving buffer

(tons)

Outslope 10 2 .01 0



## N one 27 4 .032

Pavement 13 8 .03560 Three BMP implementation and maintenance scenarios were modeled: New BMP

i n s t a l l a t i o n o n l y

, n e w B M P i n s t a l l a t i o n a n d m a i n t e n a n c e

, a n d e x i s t i n g B M P m a i n t e n a n c e

a l o n g w i t h n e w B M P i n s t a l l a t i o n a n d m a i n t e n a n c e

. I n t h o s e m o d e l i n g s c e n a r i o s

a c c o u n t i n g f o r B M P m a i n t e n a n c e

, B M P s w e r e a s s u m e d t o b e m a i n t a i n e d i n p e r p e t u i t y at

t h e i r a s s i g n e d f r e q u e n c i e s

. W h e n included

, e x i s t i n g B M P s w e r e a s s u m e d t o s t a r t t h e ir

m a i n t e n a n c e c y c l e i n p e r i o d o n e

. E a c h s c e n a r i o w a s m o d e l e d u s i n g m u l t i p l e b u d g e t

levels to assess model behavior under different bud get conditions.

3 .5 Results

3 .5a WEPP: Road e rosio n modeling r esults :

O f t h e 1 7 3 s e g m e n t s a n a l y z e d i n t h e s t u d y a r e a

, 9 9 o f t h e m ( a c c o u n t i n g f o r 3

. 6

m i l e s o f t h e s t u d y a r e a ) w e r e p r e d i c t e d t o produce zero s e d i m e n t l e a v i n g t h e b u f f e r over

t h e 3 0

- year mode l i n g p e r i o d

. Per

- s e g m e n t s e d i m e n t o u t p u t s r a n g e d f r o m

. 7 t o n s p e r y e a r

t o 0 t o n s p e r y e a r

, w i t h a m e a n o f l e s s t h a n

. 1 t o n s p e r y e a r

. W E P P : R o a d predicted a

t o t a l o f 5 5 .0 t o n s p e r y e a r o f s e d i m e n t l e a v i n g t h e r o a d a n d 3

. 0 tons o f s e d i m e n t l e a v i n g

t h e b u f f e r p e r y e a r ( T a b l e 8 )

. R a t e s o f s e d i m e n t l o s s w e r e l o w e r w i t h i n G l e n b r o o k t h a n

a c r o s s t h e e n t i r e s t u d y a r e a

. E r o s i o n r i s k d i d n o t s e e m t o foll o w a n y s p a t i a l p a t t e r n

(Figure 14 ).

I n t e r m s o f g e n e r a l t r e n d s r e l a t e d t o s p e c i f i c r o a d s e g m e n t p a r a m e t e r s

, n o

r e l a t i o n s h i p c o u l d b e e s t a b l i s h e d b e t w e e n r o a d w i d t h a n d e r o s i o n r a t e

. S e g m e n t l e n g t h

a n d r o a d g r a d i e n t

, i n c o n t r a s t

, s h o w e d w e a k p o s i t i v e r e l a t i o n s h i p s ( R 2

=

. 2 6 a n d

. 1 4

,

respectively) with erosion rate for sediment leaving th e road (Figures 15 and 16 ).61 T a b l e 8

. P r e d i c t e d s e d i m e n t l e a v i n g r o a d a n d s e d i m e n t l e a v i n g b u f f e r i n t on / y r a n d t on /acre /yr in

G l e n b r o o k C r e e k

, N V

. A v e r a g e r o a d w i d t h a c r o s s t h e e n t i r e s t u d y a r e a w a s u s e d t o c a l c u l a t e t on /acre /yr

values.

Study Area Sediment Leaving Road Sediment Leaving Buffer

ton/yr ton/acre /yr ton/yr ton/acre /yr

Entire Study Area 5 5 .0 6.1 3.0 0. 3

Glenbrook

Watershed 2 2.7 3.4 1. 6 0. 2

Note: tons are English short tons (1 short ton = 2000 pounds).

Figure 14

. Map of erosion risk by road segment, Glenbrook Creek forest road network.62 Although t h e r e w a s n o c o r r e l a t i o n b e t w e e n b u f f e r g r a d i e n t a n d s e d i m e n t l e a v i n g

t h e b u f f e r

, a negative logarithmic trend w a s e v i d e n t b e t w e e n s e d i m e n t l e a v i n g the buffer

and buffer length (R 2 = .2 1 ) (Figure 1 7 ).

Figure 1 5

. E rosion rates for sediment leaving native surface road segments at various segment l engths,

Glenbrook Creek, NV. Erosion rates were calculated using WEPP: Road erosion estimates.

Figure 1 6

. E rosion rates for sediment leaving native surface roads at various road gradients, Glenbrook

Creek, NV. Erosion rates were calculated using WEPP: Road erosion estimates. y = 0.0227x

- 1.7947

R2 = 0.2632

- 10 0 10 20 30 40 50 60 70 80 90 100

0 200 400 600 800 1000 1200Erosionrate(ton/acre/yr)

Segment length (feet)

y = 0.5221x

- 1.1747

R2 = 0.1364

- 10 0 10 20 30 40 50 60 70 80 90 100

0 5 10 15 20 25Erosionrate(ton/acre/yr)

Road gradient (%)63 Figure 17

. E rosion rates for sediment leaving the buffer from native surface roa ds at various buffer lengths,

Glenbrook Creek, NV. Erosion rates were calculated using WEPP: Road erosion estimates.

A v e r a g e e r o s i o n r a t e s o n t h r e e r o a d s u r f a c e t y p e s a r e p r e s e n t e d i n F i g u r e 1 8

.

N a t i v e s u r f a c e r o a d s h a d a n a v e r a g e e r o s i o n r a t e o f 7

. 4 t o n / acre /yr, w h i c h w a s higher

t h a n t h a t e s t i m a t e d b y W E P P : R o a d f o r g r a v e l e d a n d p a v e d s e g m e n t s

. P a v e d s e g m e n t s

e r o s i o n r a t e s w e r e e s t i m a t e d a t 5

. 1 t o n / a c r e / y r f o r s e d i m e n t l e a v i n g t h e r o a d

. E r o s i o n r a t e

fo r s e d i m e n t l e a v i n g t h e b u f f e r a d j a c e n t t o p a v e d s e g m e n t s w a s h i g h e r t h a n i n t h e other

two surface types, at .6 ton/acre /yr. y =

- 0.222ln(x) + 1.4664

R2 = 0.2121

- 0.5 0 0.5 1 1.5 2 2.5 3 3.5

0 200 400 600 800 1000 1200Sedimentleavingbuffer(ton/acre/yr)

Buffer length (feet)64 Figure 18 . Average erosion rates for three road surface types, Glenbrook Creek, NV. Erosion rates were

calculated using WEPP: Road erosion estimates.

W E P P : R o a d estimated s e g m e n t s i n loam s o i l s t o h a v e a n a v e r a g e e r o s i o n r a t e o f

18 .3 ton/acre / y r f o r s e d i m e n t l e a v i n g t h e r o a d

, t h r e e a n d a h a l f t i m e s t h a t o f s e g m e n t s i n

c l a y l o a m a n d s a n d y l o a m s o i l s ( F i g u r e 1 9 )

. S e g m e n t s i n c l a y l o a m w e r e p r e d i c t e d t o

h a v e t h e n e x t g r e a t e s t e r o s i o n r a t e f o r s e d i m e n t l e a v i n g t h e r o a d a t 4

. 9 t o n / a c r e /yr

,

f o l l o w e d b y s a n d y l o a m w i t h 3

. 8 t o n / a c r e /yr

. S e g m e n t s i n l o a m s o i l s w e r e also projected

t o h a v e t h e g r e a t e s t e r o s i o n r a t e s f o r s e d i m e n t l e a v i n g t h e b u f f e r

, a t

. 5 ton/acre /yr,

followed by sandy loam (.3 ton/acre /yr) and clay loam (.1 ton/acre /yr) , respectively. 1.8 7.4

5.1

0.2 0.3 0.6

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00

Gravel Native PavedErosionrate(ton/acre/yr)

Road surface type Sediment leaving road

Sediment leaving buffer65 Figure 19

. A verage erosion rates for native surface roads in three soil types, Glenbrook Creek, NV. Erosion

rates were calculated using WEPP: Road erosion estimates.

3 .5b BMP

- SA modeling r esults :

N e w B M P i n s t a l l a t i o n o n l y : T r e n d i n s e d i m e n t l e a v i n g t h e b u f f e r w i t h i n c r e a s i n g

i n i t i a l b u d g e t p e r p e r i o d ( h e r e a f t e r r e f e r r e d t o a s “ b u d g e t ” ) i s s h o w n i n F i g u r e 20

.

S e d i m e n t l e a v i n g t h e b u f f e r p r o d u c e d a n e g a t i v e e x p o n e n t i a l t r e n d w i t h i n creasing

b u d g e t

. N o t e t h a t t h e t h e o r e t i c a l m i n i m u m n u m b e r o f B M P s i n s t a l l e d i s z e r o

. B e l o w

$3,000, the model failed to find a feasible solution within one hour

.

T h e b e s t s o l u t i o n w a s a c h i e v e d w h e n a l l 3 8 s e g m e n t s h a d B M P s a p p l i e d t o t h e m

i n p e r i o d o n e

. S e d i m e n t w a s r e d u c e d f r o m 4 1

. 7 t o n s o v e r t h e c o u r s e o f t h e p l a n n i n g

h o r i z o n t o 1 1

. 5 t o n s t h r o u g h t h e c o u r s e o f t h e p l a n n i n g h o r i z o n

. W i t h t h i s m o d e l e d

s c e n a r i o

, a l l 3 8 B M P s w e r e i n s t a l l e d i n p e r i o d o n e w h e n b u d g e t e q u a l e d $ 2 0

, 0 0 0 ( F i g u r e

21 )

. I n c r e a s i n g b u d g e t b e y o n d t h i s l e v e l y i e l d e d n o r e d u c t i o n i n s e d i m e n t l e a v i n g t h e

buffer. 4.9 18.3

3.8

0.1 0.5 0.3

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

clay loam loam sandy loamErosionrate(ton/acre/yr)

Soil type Sediment leaving road

Sediment leaving buffer66 Figu re 20 . Sediment leaving road buffer through planning horizon with increasing in itial budget per period,

new BMP installation only model scenario

.

Figure 21

. N u m b e r o f B M P s i n s t a l l e d i n p e r i o d o n e a t v a r y i n g i n i t i a l b u d g e t s p e r p e r i o d

, n e w B M P

installation only model scenario

.

N u m b e r o f B M P s i n s t a l l e d i n p e r i o d o n e i n c r e a s e d w i t h i n i t i a l b u d g e t p e r p e r i o d

.

P r o p o r t i o n o f s e g m e n t s w i t h o u t s l o p i n g c h o s e n a s a n a p p r o p r i a t e B M P a l s o i n c r e a s e d

w i t h b u d g e t

. I n s e v e r a l i n s t a n c e s

, s o l u t i o n s a t t w o d i f f e r e n t b u d g e t s y i e l d e d d e c r e a s e s i n

s e d i m e n t l e a v i n g t h e b u f f e r w h i l e h a v i n g t h e s a m e n u m b e r o f B M P s i n s t a l l e d i n p e r i o d

o n e

. I n a l l o f t h e s e i n s t a n c e s

, n u m be r o f s e g m e n t s w h e r e o u t s l o p i n g w a s i n s t a l l e d a s a

B M P w a s g r e a t e r i n t h e s o l u t i o n p r o d u c i n g l e s s s e d i m e n t l e a v i n g t h e b u f f e r

. O u t s l o p i n g 11.4 11.6 11.8 12 12.2 12.4 12.6 12.8 13

0 5000 10000 15000 20000 25000 30000 35000 40000Sedimentleavingbufferthroughcourseofplanninghorizon(tons)

Initial budget per period ($)

0 5 10 15 20 25 30 35 4030004000500060007000800090001000011000120001300014000150001600017000180001900020000NumberofBMPsinstalledinperiodone

Initial budget per period ($) outsloping

7 drain dips

3 drain dips

drain dips67 is a h i g h l y e f f e c t i v e B M P f o r reducing sediment l e a v i n g t h e r o a d a n d b u f f e r

, b u t a l s o

t e n d s t o b e m o r e e x p e n s i v e t h a n d r a i n d i p s ( L u c e a n d B l a c k 2 0 0 1 a

, E l l i o t e t a l

. 2 0 0 9

,

USDA 2008).

F i g u r e 2 2 s h o w s t h e n u m b e r o f s e g m e n t s w h e r e B M P s w e r e i n s t a l l e d i n e a c h

p e r i o d

. A t $ 3

, 0 0 0

, a l l B M P s w e r e i n s t a l l e d i n t h e f i r s t s e v e n p e r i o d s

. A s b u d g e t

increased, the number of periods r equired for all BMPs to be installed was reduced.

Figure 2 2

. N u m b e r o f B M P s i n s t a l l e d i n e a c h p e r i o d a t v a r y i n g i n i t i a l b u d g e t s p e r p e r i o d

, n e w B M P

installation only model scenario

.

N e w B M P i n s t a l l a t i o n a n d m a i n t e n a n c e : T h e n e w B M P i n s t a l l a t i o n a n d

m a i n t e n a n c e m o d e l i n g s c e n a r i o d i s p l a y e d a n e g a t i v e e x p o n e n t i a l t r e n d s i m i l a r t o t h e

t r e n d d i s p l a y e d w i t h p r e v i o u s m o d e l e d s c e n a r i o ( F i g u r e 2 3 )

. B e l o w $ 6

, 0 0 0

, t h e m o d e l

failed to produce feasible solutions in one hour

. 0 5 10 15 20 25 30 35 4030004000500060007000800090001000011000120001300014000150001600017000180001900020000NumberofBMPsinstalledthroughcourseofplanninghorizon

Initial budget per period ($) Period 7

Period 6

Period 5

Period 4

Period 3

Period 2

Period 168 Figure 2 3

. S e d i m e n t l e a v i n g r o a d b u f f e r t h r o u g h p l a n n i n g h o r i z o n w i t h i n c r e a s i n g i n i t i a l b u d g e t p e r p e r i o d

for new BMP installation and maintenance model scenario

.

A s w i t h t h e p r e v i o u s m o d e l i n g s c e n a r i o

, m i n i m u m s e d i m e n t l e a v i n g t h e b u f f e r

t h r o u g h t h e c o u r s e o f t h e p l a n n i n g h o r i z o n w a s 1 1.5 t o n s

. T h e l e s s

- than

- p e r f e c t n e g a t i v e

e x p o n e n t i a l t r e n d s e e n i n F i g u r e 2 3 s e r v e d a s e v i d e n c e o f t h e s o l u t i o n q u a l i t y

-

c o m p u t a t i o n t i m e t r a d e o f f t h a t o c c u r s w i t h h e u r i s t i c o p t i m i z a t i o n

. H a d t h e m o d e l b e e n

r u n f o r l o n g e r p e r i o d s o f t i m e a t e a c h b u d g e t l e v e l

, t h e c u r v e w o u l d l i k e l y b e c o m p l e t e l y

s m o o t h

. W i t h t h i s s c e n a r i o

, a l l 3 8 B M P s c a n b e i n s t a l l e d i n p e r i o d o n e a t a $ 3 4

, 0 0 0

budget.

F i g u r e 2 4 s h o w s t h e d i s t r i b u t i o n o f t y p e s o f B M P s i n s t a l l e d a t v a r y i n g b u d g e t s

.

W h i l e n o d i s t i n c t p a t t e r n w a s e v i d e n t

, a t $ 6

, 0 0 0 b u d g e t t w o s e g m e n t s h a d n o t r e a t m e n t

c h o s e n a s t h e b e s t p o s s i b l e o p t i o n

. T h i s r e s u l t i n d i c a t e s t h a t b u d g e t w a s s o l i m i t e d t h a t

n e i t h e r B M P i n s t a l l a t i o n n o r m a i n t e n a n c e w a s f e a s i b l e f o r t h e s e t w o s e g m e n t s

. H a d t h e r e

been sufficient budget available for installation, the model would have installed BMPs on

these segments late in the planning horizon so as to avoid maintenance costs. 11.4 11.6 11.8 12 12.2 12.4 12.6 12.8

0 5000 10000 15000 20000 25000 30000 35000 40000 45000Sedimentleavingbufferthroughcourseofplanninghorizon(tons)

I nitial budget per period ($)69 Figure 24

. N u m b e r a n d t y p e o f B M P s i n s t a l l e d o n t r e a t a b l e r o a d s e g m e n t s a t v a r y i n g i n i t i a l b u d g e t s p e r

period for new BMP installation and maintenance model scenario

.

Figure 25 presents t h e n u m b e r a n d t y p e s o f B M P s i n s t a l l e d i n p e r i o d o n e a t

v a r y i n g b u d g e t s f o r t h e n e w B M P i n s t a l l a t i o n a n d m a i n t e n a n c e scenario. Again

, number

of outsloped segments installed in period one relative to drain dips increased with budget.

Cost

- b e n e f i t t r a d e o f f s s i m i l a r t o t h o s e s e e n i n t h e p r e v i o u s l y m o d e l e d s c e n a r i o c o u l d a l s o

be found here

.

Figure 25

. N u m b e r a n d t y p e s o f B M P s i n s t a l l e d i n p e r i o d o n e a t v a r y i n g i n i t i a l b u d g e t s p e r p e r i o d for new

BMP installation and maintenance model scenario

. 0 5 10 15 20 25 30 35 40NumberofBMPsinstalled

Initial budget per period ($) none

outsloping

7 drain dips

3 drain dips

drain dips

0 5 10 15 20 25 30 35 40NumberofBMPsinstalledinperiodone

Initial budget per period ($) outsloping

7 drain dips

3 drain dips

drain dips70 T h e n u m b e r o f s e g m e n t s t r e a t e d d u r i n g a g i v e n p l a n n i n g p e r i o d a t v a r y i n g

b udgets i s p r e s e n t e d i n F i g u r e 2 6

. A s w i t h t h e p r e v i o u s l y m o d e l e d s c e n a r i o

, t h e n u m b e r

of BMPs installed in period one increased with budget.

Figure 26

. N u m b e r o f B M P s i n s t a l l e d i n e a c h p e r i o d a t v a r y i n g i n i t i a l b u d g e t s p e r p e r i o d for n e w B M P

i n s t a l l a t i o n a n d maintenance m o d e l s c e n a r i o

. N o t e t h a t n o t r e a t m e n t i s a p p l i e d t o t w o s e g m e n t s a t $ 6

, 0 0 0

initial budget per period.

E x i s t i n g B M P m a i n t e n a n c e a n d n e w B M P i n s t a l l a t i o n a n d m a i n t e n a n c e : T h e b e s t

s o l u t i o n a c h i e v e d w i t h t h i s s c e n a r i o w a s t h e s a m e a s w i t h t h e p r e v i o u s t w o m o d e l e d

scenarios

- 11.5 t o n s o f s e d i m e n t l e a v i n g t h e b u f f e r o v e r t h e c o u r s e o f t h e p l a n n i n g

horizon ( F i g u r e 2 7 )

. M a i n t e n a n c e o f e x i s t i n g B M P s r e q u i r e d approximately $3 5,000

minimum initial budget. Period 1 3 , with numerous preexisting BMPs hav ing maintenance

f r e q u e n c i e s o f 2

, 3

, o r 4 y e a r s ( i n s t a l l e d i n p e r i o d o n e )

, r e q u i r e d t h e g r e a t e s t i n i t i a l

budget

. A s a r e s u l t

, a n y new B M P s w i t h a t h r e e

- y e a r m a i n t e n a n c e f r e q u e n c y ( s u c h a s

outsloping) co u l d n o t b e i n s t a l l e d i n p e r i o d o n e u n t i l b u d g e t w a s i n c r e a s e d b e y o n d t h i s

minimum level. 0 5 10 15 20 25 30 35 40NumberofBMPsinstalledthroughcourseofplanninghorizon

Initial budget per period ($) Period 8

Period 7

Period 6

Period 5

Period 4

Period 3

Period 2

Period 171 Figure 27

. S e d i m e n t l e a v i n g b u f f e r t h r o u g h c o u r s e o f p l a n n i n g h o r i z o n a t v a r y i n g i n i t i a l b u d g e t s p e r p e r i o d

for existing BMP maintenance, new BMP installation, and new BMP maintenance model scenario

.

A g a i n

, s e d i m e n t l e a v i n g t h e b u f f e r d e c r e a s e d e x p o n e n t i a l l y w i t h i n c r e a s e i n

b u d g e t

. W i t h t h i s s c e n a r i o

, a b u d g e t o f $ 5 7

, 0 0 0 w a s n e c e s s a r y f o r a l l B M P s t o b e

installed in period one.

F i g u r e 2 8

. N u m b e r a n d t y p e o f B M P s i n s t a l l e d i n p e r i o d o n e a t v a r y i n g i n i t i a l b u d g e t s p e r p e r i o d for

existing BMP maintenance, new BMP installation, and new BMP maintenance model scenario

.

W h e n i n s t a l l a t i o n o f n e w B M P s a n d m a i n t e n a n c e o f a l l B M P s w a s a c c o u n t e d f o r

,

t h e n u m b e r o f B M P s i n s t a l l e d i n p e r i o d o n e i n c r e a s e d l i n e a r l y a s b u d g e t i n c r e a s e d 11.4 11.6 11.8 12 12.2 12.4 12.6

30000 35000 40000 45000 50000 55000 60000 65000 70000Sedimentleavingbufferthroughcourseofplanninghorizon(tons)

I nitial budget per period ($)

0 5 10 15 20 25 30 35 4036000370003800039000400004100042000430004400045000460004700048000490005000051000520005300054000550005600057000NumberofBMPsinstalledinperiodone

initial budget per period ($) outsloping

7 drain dips

3 drain dips

drain dips72 ( F i g u r e 2 8 )

. A s a r e s u l t o f a c c o u n t i n g f o r m a i n t e n a n c e c o s t s

, t h e s o l u t i o n b e c a m e m o r e

c o n s t r a i n e d

, m a k i n g t h e B M P i n s t a l l a t i o n s c e n a r i o l e s s v a r i a b l e t h a n w i t h t h e p r e v i o u s

s c e n a r i o

. O u t s l o p e d s e g m e n t s i n c r e a s e d w i t h b u d g e t a s w i t h t h e t w o p r e v i o u s l y m o d e l e d

scenarios.

Figure 29

. N u m b e r o f B M P s i n s t a l l e d p e r p e r i o d a t v a r y i n g i n i t i a l b u d g e t s p e r p e r i o d f o r e x i s t i n g B M P

maintenance, new BMP installation, and new BMP maintenance model scenario

.

I n g e n e r a l

, n u m b e r o f p e r i o d s r e q u i r e d t o i n s t a l l B M P s o n a l l s e g m e n t s d e c r e a s e d

with increase in budget (Figure 29 )

.

3 .6 Discussion

3 .6a Discussion of WEPP: Road modeling r esults:

T h e o u t s t a n d i n g B M P i n f r a s t r u c t u r e o n G l e n b r o o k C r e e k ’ s f o r e s t r o a d s p a r t i a l l y

explains t h e l a c k o f s p a t i a l t r e n d i n e r o s i o n r i s k p r e d i c t i o n

. T h e L T B M U ’ s B M P

i n s t a l l a t i o n a n d m a i n t e n a n c e r e g i m e n

, c o u p l e d w i t h t h e d r y c l i m a t e f o u n d i n t h i s

w a t e r s h e d

, e x p l a i n s t h e m i n i m a l a m o u n t o f s e d i m e n t p r e d i c t e d t o b e l e a v i n g t h e r o a d a n d

buffer. 0 5 10 15 20 25 30 35 4036000370003800039000400004100042000430004400045000460004700048000490005000051000520005300054000550005600057000NumberofBMPsinstalledthroughcourseofplanninghorizon

Initial budget per period ($) Period 5

Period 4

Period 3

Period 2

Period 173 T h o u g h c o r r e l a t i o n s b e t w e e n s e d i m e n t l e a v i n g t h e r o a d a n d b u f f e r f o r s e g m e n t

l e n g t h

, r o a d g r a d i e n t

, a n d b u f f e r l e n g t h w e r e n o t s t r o n g

, t h e t r e n d s d o s u g g e s t a g r e e m e n t

b e t w e e n W E P P : R o a d p r e d i c t i o n s a n d e m p i r i c a l r e s e a r c h ( L u c e a n d B l a c k 1 9 9 9

, L u c e

a n d B l a c k 2 0 0 1 a )

. N o t e t h a t regression s w e r e n o t f i t t e d w i t h t h e i n t e n t i o n o f p r e d i c t i n g

p a r a m e t e r r e s p o n s e w i t h i n W E P P : R o a d ; r a t h e r

, r e g r e s s i o n s w e r e u s e d t o e v a l u a t e

whether parameter response within WEPP: Road matched empirical research

.

M o d e l e d d i f f e r e n c e s i n s e d i m e n t l e a v i n g t h e r o a d a n d b u f f e r for t h e t h r e e s u r f a c e

types were not anticipated . While the reduction in sediment leaving the road and buffer in

g r a v e l e d s e g m e n t s c o m p a r e d t o n a t i v e s e g m e n t s w a s e x p e c t e d

, p a v e m e n t

, h a v i n g a n

i m p e r v i o u s s u r f a c e

, s h o u l d p r o d u c e e v e n l e s s s e d i m e n t l e a v i n g t h e r o a d t h a n g r a v e l e d

s e g m e n t s

. T h i s w a s n o t t h e c a s e w i t h W E P P : R o a d p r e d i c t i o n s f o r G l e n b r o o k C r e e k

.

N u m e r o u s p a v e d s e g m e n t s i n G l e n b r o o k C r e e k h a d u n v e g e t a t e d d i t c h e s

, w h i c h c o u l d

p a r t i a l l y e x p l a i n w h y t h e e r o s i o n r a t e f o r s e d i m e n t l e a v i n g t h e r o a d wa s g r e a t e r t h a n

d o u b l e t h a t f o u n d o n g r a v e l e d s e g m e n t s

. D u e t o m o r e a n d f l a s h i e r r u n o f f l e a v i n g p a v e d

s e g m e n t s

, b u f f e r s e d i m e n t c a n be m o r e r e a d i l y e n t r a i n e d than on road segments with

o t h e r s u r f a c e t y p e s

. I n s o m e c a s e s

, p a v e d segments i n G l e n b r o o k C r e e k h a d a r m o r e d

drainage surfaces below the road, but these BMPs cannot be modeled in WEPP: Road. As

a r e s u l t

, r o a d s e g m e n t s w i t h t h i s s u r f a c e t y p e we r e g e n e r a l l y p r e d i c t e d t o h a v e higher

average erosion rate s for sediment leaving the buffer tha n the other two surface types. N o

c o n c l u s i o n s c a n b e d r a w n r e g a r d i n g a c c u r a c y o f predictions for s e d i m e n t l e a v i n g t h e

buffer. P u b l i s h e d f i e l d research c o u p l e d w i t h a s e n s i t i v i t y a n a l y s i s o f W E P P : R o a d

s u g g e s t t h a t t h e m o d e l m a y b e o v e r e s t i m a t i n g s e d i m e n t l e a v i n g p a v e d r o a d s e g m e n t s

.74 F u r t h e r i n v e s t i g a t i o n i s n e c e s s a r y

, h o w e v e r

, to d e t e r m i n e w h e t h e r s e d i m e n t l e a v i n g

paved segments is truly being overpredicted

.

P a r t i c l e s i z e relationships a n d s o i l c o h e s i v e s t r e n g t h s g o v e r n W E P P : R o a d ’ s

e r o s i o n p r e d i c t i o n s a c r o s s d i f f e r e n t s o i l t y p e s ( C h a p t e r 2 )

. F o r e s t s o i l s h i g h e s t i n s i l t

c o n t e n t h a v e b e e n f o u n d t o b e m o s t e r o d i b l e

, h a v i n g l e s s c o h e s i v e s t r e n g t h t h a n clay

- rich

soils a n d s m a l l e r p a r t i c l e s i z e s t h a n s a n d y s o i l s ( L u c e a n d B l a c k 2 001 a )

. W i t h l o a m s o i l s

h a v i n g t h e g r e a t e s t s i l t c o n t e n t o f t h e s e t h r e e s o i l t y p e s

, W E P P : R o a d ’ s estimate of

s e d i m e n t l e a v i n g t h e r o a d i n t h i s s o i l t y p e i s appropriate t h o u g h q u i t e l a r g e

. I n c o n t r a s t

,

e s t i m a t e s f o r s e d i m e n t l e a v i n g t h e b u f f e r were suspect

. S e g m e n t s i n c l a y l o a m

, hav ing

l e s s m a s s i v e p a r t i c l e s i z e s

, c o u l d b e e x p e c t e d t o p o s t t h e g r e a t e s t l o s s e s f r o m t h e b u f f e r

.

T h i s d i s c r e p a n c y

, c o u p l e d w i t h t h e h i g h e r o s i o n r a t e e s t i m a t e f o r s e d i m e n t l e a v i n g t h e

r o a d

, i s l i k e l y d u e t o t h e h i g h s l o p e s

, l o n g c o n t i g u o u s s e g m e n t l e n g t h s

, a n d f e w B M P s

found on segments in loam soils

. Similar confounding factors may be influencing erosion

rate i n o t h e r s o i l t y p e s

. F i e l d v a l i d a t i o n u s i n g s t r a t i f i e d s a m p l i n g w o u l d b e n e c e s s a r y t o

discern the true effect of all three soil type s on sediment leaving the road and buffer.

S e g m e n t l e n g t h

, r o a d g r a d i e n t

, b u f f e r l e n g t h

, a n d s u r f a c e t y p e a p p e a r t o b e t h e

primary drivers for predicted erosion in the Glenbrook watershed. The weak

, nonexistent

,

o r c o n f o u n d e d s i g n a l s f r o m s p e c i f i c parameters a f f e c t i n g s e v e r i t y o f e r o s i o n i m p a c t

h i g h l i g h t t h e i n t e r p l a y o f m u l t i p l e f a c t o r s i n d i c t a t i n g sediment l o s s e s f r o m a g i v e n r o a d

segment. T h e s e r e s u l t s a l s o r e f l e c t t h e c o m p l e x i t y o f p r o c e s s

- b a s e d r o a d e r o s i o n

prediction.75 C o m p a r i s o n o f p r e d i c t i o n s w i t h e m p i r i c a l s t u d i e s : W E P P : R o a d B a t c h r e s u l t s fall

w i t h i n t h e r a n g e o f e m p i r i c a l r e s u l t s f o u n d i n o t h e r s t u d i e s

. M e g a h a n a n d K i d d ( 1 9 7 2 )

measured l e s s t h a n

. 1 ton /acre /yr o f b a c k g r o u n d e r o s i o n i n g r a n i t i c s o f t h e I d a h o

Batholit h

, w h i c h a r e l e s s e r o d i b l e t h a n t h e v o l c a n i c s u b s t r a t e s f o u n d i n t h e L a k e T a h o e

Basin ( G r i s m e r a n d H o g a n

, 2 0 0 4 ) b u t s i m i l a r t o t h e m u c h o f t h e p a r e n t m a t e r i a l f o u n d in

G l e n b r o o k C r e e k

. I n c o n t r a s t

, e r o s i o n r a t e s g r e a t e r t h a n 4 0 t o n / a c r e / y r a r e r o u t i n e l y

ob s e r v e d o n f o r e s t r o a d s ( G r a c e 2 0 0 8 )

. T a b l e 9 c o n t a i n s s o m e p u b l i s h e d e r o s i o n r a t e s f o r

reference. ( For more p ublished reference values, see Elliot and Foltz 2001).

Table 9

. F o r e s t r o a d e r o s i o n r a t e s f r o m m u l t i p l e p u b l i s h e d s t u d i e s

. N o t e t h a t t h e s e r a t e s c o m e f r o m a

v a r i e t y o f c l i m a t e s

, s o i l t y p e s

, r o a d d e s i g n s

, t r a f f i c l e v e l s

, s t u d y d e s i g n s

, a n d s a m p l e s i z e s

. R a t e s from

e i t h e r n a t i v e o r g r a v e l e d s u r f a c e r o a d s

. R e p o r t e d n u m b e r s a r e a v e r a g e s u n l e s s s p e c i f i e d o t h e r w i s e

. V a l u e s

are included here as a general reference against predicted WEPP: Road values.

Authors/source Erosion rate

(ton/acre/yr) Traffic Comments

Megahan and

Kidd 1972 32 .0 Logging /Truck Idaho Batholith, newly constructed

roads

Foltz 1996 1.4 Logging w estern Oregon, good aggregate

(graveled road)

Luce and Black

2001 b 4.4 Logging /Truck w estern Oregon, not graded, less

than one year study

Fransen et al.

2001 4.0 Unknown New Zealand, granitic, included

cutslope contribution

Sugden and

Woods 2007 2.4 Logging/Truck Belt Supergroup, w estern Montana

Sugden and

Woods 2007 2.3 Logging/Truck Glacial till, w estern Montana

T h e s e g e n e r a l n u m b e r s c a n b e c o m p a r e d w i t h e m p i r i c a l r e s u l t s s p e c i f i c t o t h e

Lake Tahoe area. On the west slope of the Sierra Nevada range, Coe (2006) found a mean

er o s i o n r a t e of 1

. 4 t o n / a c r e /yr o n n a t i v e s u r f a c e r o a d s o v e r three w e t s e a s o n s

( a p p r o x i m a t e l y O c t o b e r t h r o u g h June )

. D u r i n g t h e f i r s t w e t s e a s o n o f d a t a c o l l e c t i o n

,

w h e r e a v e r a g e a n n u a l p r e c i p i t a t i o n w a s n e a r t h e l o n g

- t e r m a v e r a g e o f 1 3 0 0 m m

, 3.676 ton/acre of sediment w e r e m e a s u r e d l e a v i n g t h e r o a d

. In comparison

, W E P P : R o a d

e r o s i o n p r e d i c t i o n s y i e l d ed an a v e r a g e r a t e o f 7.4 ton/acre / y r a c r o s s a l l n a t i v e s u r f a c e

s e g m e n t s i n the s t u d y a r e a

. P r e c i p i t a t i o n i n C o e ’ s s t u d y s i t e w a s approximately o n e a n d a

half times the average annual precipitation g e n e r a t e d b y P R I S M f o r W E P P : R o a d e r o s i o n

e s t i m a t e s i n G l e n b r o o k C r e e k (33

. 2 i n c h e s

, o r approximately 843 mm)

. A v e r a g e r o a d

gradients, se g m e n t l e n g t h s

, a n d p a r e n t m a t e r i a l s were comparable f o r b o t h s t u d i e s

, but

r o a d d e s i g n s a n d t r a f f i c l e v e l s f o r s e g m e n t s i n C o e ’ s s t u d y a r e unknown

. C o e ’ s s t u d y

segments were in primarily loam soils.

G r a v e l e d s e g m e n t s i n t h e C o e s t u d y a l s o y i e l d e d a l o w e r a verage e r o s i o n r a t e o f

.5 ton/acre /yr, c o m p a r e d t o 1

. 8 t o n / a c r e /yr predicted o v e r 3 0 y e a r s i n G l e n b r o o k C r e e k

.

F o r b o t h n a t i v e s u r f a c e a n d g r a v e l e d s e g m e n t s

, W E P P : R o a d e s t i m a t e s f o r sediment

leaving the road in Glenbrook Creek are higher than regional emp irical values

.

N o e m p i r i c a l v a l u e s f o r s e d i m e n t l e a v i n g r o a d s e g m e n t b u f f e r s i n t h e L a k e T a h o e

B a s i n c o u l d b e f o u n d

. T o g i v e s o m e p e r s p e c t i v e t o e s t i m a t e s f o r s e d i m e n t l e a v i n g t h e

buffer, S i m o n a n d o t h e r s f o u n d 9

. 7 ton / y r o f f i n e s e d i m e n t e n t e r i n g L a k e T a h o e f r o m

G l e n b r o o k C r e e k i n 2 0 0 3

. E v a l u a t e d a g a i n s t W E P P : R o a d o u t p u t s

, f o r e s t r o a d s i n t h i s

w a t e r s h e d a r e r e s p o n s i b l e f o r a p p r o x i m a t e l y 1 6 % o f G l e n b r o o k C r e e k ’s yearly sediment

load.

W E P P : R o a d i s i n t h e p r o c e s s o f b e i n g p a r a m e t e r i z e d s p e c i f i c a l l y f o r t h e L a k e

T a h o e B a s i n b y t h e R o c k y M o u n t a i n R e s e a r c h S t a t i o n i n M o s c o w

. T h i s p a r a m e t e r i z e d

m o d e l v e r s i o n m a y m i t i g a t e s o m e o f t h e d i f f e r e n c e s b e t w e e n e m p i r i c a l r e s e a r c h a n d

m o d e l e d p r e d i c t i o n s

. C u r r e n t l y

, t h e T A H O E C A S N O T E L s i t e i s t h e c l o s e s t b a s e s t a t i o n77 a v a i l a b l e w i t h i n t h e W E P P : R o a d c l i m a t e l i b r a r y

. S i t e

- s p e c i f i c c l i m a t e d a t a m a y a l s o

reduce prediction disagreement with field

- derived data.

3 .6b Discussion of BMP

- SA modeling r esults :

D e s p i t e t h e p o t e n t i a l d e v i a t i o n o f s o m e e r o s i o n p r e d i c t i o n s f r o m r e a l i t y

, B M P

- SA

a n d i t s a s s o c i a t e d m e t h o d o l o g y a r e a p p l i c a b l e n o m a t t e r w h e t h e r p r e d i c t i o n s a g r e e w i t h

a b s o l u t e v a l u e s f o u n d i n t h e f i e l d

. B M P

- S A u s e s p r e d i c t e d r e l a t i v e d i f f e r e n c e s b e t w e e n

t w o t r e a t m e n t s t o i d e n t i f y t h e m o s t a p p r o p r i a t e B M P i m p l e m e n t a t i o n a n d m a i n t e n a n c e

s c e n a r i o

. A s s u m p t i o n s w i t h i n t h e m o d e l n e v e r c h a n g e

, s o t h o u g h a b s o l u t e v a l u e s m a y b e

i n c o r r e c t

, r e l a t i v e p r e d i c t e d d i f f e r e n c e s b e t w e e n s e g m e n t s ( a n d a s s o c i a t e d B M P s ) w i l l be

consistent.

T h e b e s t p o s s i b l e B M P i n s t a l l a t i o n s c e n a r i o w a s a c h i e v e d w i t h a l l t h r e e m o d e l i n g

s c e n a r i o s

, a l b e i t a t h i g h e r b u d g e t l e v e l s w h e n m a i n t e n a n c e o f n e w a n d e x i s t i n g B M P s

w a s a c c o u n t e d f o r

. U n d e r t h e b e s t p o s s i b l e s o l u t i o n

, s e d i m e n t l e a v i n g t h e b u f f e r w a s

reduced by greater than 72 % if compared to buffer sediment outputs should no treatments

b e i n s t a l l e d t h r o u g h t h e c o u r s e o f t h e p l a n n i n g h o r i z o n ( T a b l e 1 0 )

. W i t h r e s p e c t t o t h e 3 8

t r e a t e d s e g m e n t s

, s e d i m e n t w a s r e d u c e d b y nearly 93 % i f c o m p a r e d t o b u f f e r s e d i m e n t

outputs should no treatments be installed through the course of the planning horizon. This

s a v i n g s i s s u b s t a n t i a l c o n s i d e r i n g t h a t t h e G l e n b r o o k w a t e r s h e d i s i n a d r y c l i m a t e a n d

a l r e a d y h a s n u m e r o u s w e l l

- m a i n t a i n e d B M P s

. A s s u m i n g t h a t m a n a g e r s a r e a w a r e o f h o t

s p o t s o n t h e r o a d n e t w o r k

, i n s t a l l i n g a n d m a i n t a i n i n g B M P s w i t h o u t u s i n g t h i s m o d e l

could yield significant sediment savings. Budget, maintenance, and equipment scheduling78 c o n s t r a i n t s

, h o w e v e r

, w o u l d n o t b e a c c o u n t e d f o r

. A l s o

, s e d i m e n t m a y n o t b e m i n i m i z e d

to the greatest degree possible.

U s i n g t h e b e s t a v a i l a b l e cost e s t i m a t e s f o r r o a d B M P i n s t a l l a t i o n a n d

m a i n t e n a n c e

, s e d i m e n t l e a v i n g t h e b u f f e r c a n b e m i n i m i z e d a t $ 5 7

, 0 0 0 b u d g e t p e r p e r i o d

t h r o u g h t h e c o u r s e o f a t w e n t y

- y e a r p l a n n i n g h o r i z o n

. T h i s r e s u l t a s s u m e s t h a t e x i s t i n g

B M P s a n d n e w B M P s a r e regularly maintained d u r i n g t h e h o r i z o n

. A l l B M P s m u s t b e

installed during period one to maximize sediment savings.

T able 10 . Reduction in predicted sediment leaving the buffer using BMP

- SA model.

Portion of study

area Sediment leaving

buffer with no new

BMPs installed (tons

through planning

horizon) Sediment leaving

buffer with best

possible BMP

installation scenario

(tons through

planning horizon) Percent reduction

Entire study area 4 1.7 1 1.5 72.4 %

38 treatable

segments 3 2.5 2.3 92.9 %

Note: sediment has been discounted using 4% discount rate.

T h e r e w e r e n o i n s t a n c e s w h e r e p a v i n g w a s c h o s e n a s a n a p p l i c a b l e n e w B M P

. I n

e v e r y i n s t a n c e w h e r e p a v e m e n t w a s a p o t e n t i a l B M P o p t i o n

, W E P P : R o a d m o d e l o u t p u t s

i n d i c a t e d t h a t p a v e m e n t i n c r e a s e d s e d i m e n t l e a v i n g t h e b u f f e r a b o v e e x i s t i n g l e v e l s

.

O t h e r r e s e a r c h e r s h a v e h a d s i m i l a r r e s u l t s i n a p p l y ing W E P P : R o a d t o p a v e d r o a d

segments in the Lake Tahoe Basin (Briebart et al. 2006).

3.7 Co nclusions

W h e n f o r e s t r o a d B M P p l a n n i n g i s s u e s a r e a p p r o a c h e d f r o m t h e o n e

- o r f e w

-

s e g m e n t p e r s p e c t i v e

, w a t e r s h e d

- s c a l e s e d i m e n t a t i o n

, m a i n t e n a n c e

, a n d e q u i p m e n t79 p l a n n i n g c o n c e r n s c a n n o t b e a d d r e s s e d

. A t t h e w a t e r s h e d s c a l e

, h o w e v e r

, a c c o u n t i n g f o r

a l l o f t h e s e i s s u e s a n d c o n c e r n s f o r e v e r y r o a d s e g m e n t b e c o m e s h i g h l y c o m p l i c a t e d a n d

,

i n s o m e c a s e s

, m a y b e s i m p l y t o o c o m p l e x t o a d d r e s s u s i n g c o n v e n t i o n a l m e t h o d s

. T h e

m e t h o d o l o g y p r e s e n t e d h e r e m a k e s w a t e r s h e d

- s c a l e f o r e s t r o a d B M P p l a n n i n g f e a s i b l e

.

Multi ple constraints can be accounted for consistently for every segment across the entire

road network.

T h i s r e s e a r c h t e s t e d a m e t h o d ology f o r i n c r e a s i n g e f f i c i e n c y o f B M P planning on

a f o r e s t r o a d n e t w o r k

. R o a d

- r e l a t e d s e d i m e n t l e a v i n g t h e f o r e s t b u f f e r w a s m i n i m i z e d

o v e r t h e c o u r s e o f a p l a n n i n g h o r i z o n w h i l e a c c o u n t i n g f o r b u d g e t c o n s t r a i n t s a s w e l l a s

e q u i p m e n t s c h e d u l i n g c o n s i d e r a t i o n s

. T h e s o l u t i o n s p r e s e n t e d h e r e u s e d m o d e l e d WEPP:

R o a d e r o s i o n d a t a f r o m a h i g h

- d e n s i t y r o a d s u r v e y a s w e l l a s g u i d e l i n e s for prioritizing

appropriate BMPs f o r a g i v e n r o a d s e g m e n t

. T o m i n i m i z e s e d i m e n t l e a v i n g t h e r o a d

b u f f e r

, t h i s d a t a w a s i n p u t i n t o a n a d a p t e d s i m u l a t e d a n n e a l i n g o p t i m i z a t i o n a l g o r i t h m

.

U n d e r t h e b e s t B M P i m p l e m e n t a t i o n s c e n a r i o

, predicted sediment leavi n g t h e r o a d b u f f e r

was reduced by greater than 70% over the course of a planning horizon. From these tests,

i t c a n b e c o n c l u d e d t h a t W E P P : R o a d e r o s i o n m o d e l i n g c o m b i n e d w i t h simulated

a n n e a l i n g o p t i m i z a t i o n p r o v i d e s a v i a b l e a p p r o a c h t o w a t e r q u a l i t y i s s u e s a s s o c i a t e d w i t h

s e d i m e n t a t i o n f r o m f o r e s t r o a d s

. W h i l e t h e d a t a u s e d h e r e i s f r o m t h e L a k e T a h o e B a s i n

,

this methodology can be applied to any watershed. This methodology is also applicable at

a s c a l e g r e a t e r t h a n a s i n g l e w a t e r s h e d

, t h o u g h p r o b l e m c o m p l e x i t y m a y s u b s t a n t i a l l y

increase.

S e d i m e n t s a v i n g s w i t h B M P

- S A w a s c o n s i d e r a b l e

, i n p a r t b e c a u s e l i t t l e s e d i m e n t

w a s p r e d i c t e d t o l e a v e t h e r o a d b u f f e r f r o m t h e G l e n b r o o k C r e e k w a t e r s h e d

. I f p r e d i c t e d80 s e d i m e n t l e a v i n g t h e r o a d b u f f e r w a s g r e a t e r

, p e r c e n t d e c r e a s e i n s e d i m e n t l e a v i n g t h e

b u f f e r a s a r e s u l t o f B M P i n s t a l l a t i o n c o u l d b e lower

. I n a w a t e r s h e d w i t h o u t a w e l l

-

d e v e l o p e d B M P i n f r a s t r u c t u r e

, h o w e v e r

, t h e r e w o u l d m o r e p o t e n t i a l f o r a t o o l l i k e B M P

-

SA to minimize sediment leaving the buffer.

T h e r e a r e t w o c r i t i c a l a s s u m p t i o n s o f t h i s m o d e l i n g e x e r c i s e

. O n e i s t h a t B M P s

m u s t b e m a i n t a i n e d a t a p p r o p r i a t e i n t e r v a l s i n p e r p e t u i t y

, o t h e r w i s e m o n e y s p e n t

i n s t a l l i n g B M P s i s n o t w o r t h w h i l e

. I n a d d i t i o n

, t h i s m o d e l i n g p r o c e s s r e l i e s o n t h e

a c c u r a c y o f r o a d s e d i m e n t a t i o n p r e d i c t i o n f o r d e t e r m i n i n g p r o b l e m a t i c r o a d s e g m e n t s

a n d t h e e f f e c t s o f B M P i n s t a l l a t i o n o n s e d i m e n t s a v i n g s

. W E P P : R o a d i s a n e a s y

- to

- use,

process

- b a s e d m o d e l i n t e r f a c e f o r e s t i m a t i n g r o a d s e d i m e n t l o s s e s a n d h a s g a i n e d

w i d e s p r e a d u s e a m o n g r e s e a r c h e r s a n d m a n a g e r s

. I t i s i m p o r t a n t t o n o t e t h a t W E P P :

R o a d e s t i m a t e s h a v e b e e n s h o w n t o d e v i a t e f r o m f i e l d m e a s u r e m e n t s b y + /

- 5 0 % ( E l l i o t

e t a l

. 1 9 9 9 )

. A c c o r d i n g l y

, t h e i m p o r t a n c e o f h a v i n g a c c u r a t e m o d e l i n p u t s c a n n o t b e

understated.

B M P i m p l e m e n t a t i o n i s o f t e n s i t e

- s p e c i f i c i n n a t u r e

. F o r t h a t r e a s o n

, some hot

s p o t s m a y n o t b e a b l e t o b e t r e a t e d u s i n g o n e o f o n l y a h a n d f u l o f g e n e r i c B M P s ; o n l y

p r o f e s s i o n a l j u d g m e n t i n t h e f i e l d m a y p r o v i d e t h e i d e a l o p t i o n i n s u c h s i t u a t i o n s

. With

th i s p o i n t i n m i n d

, c o u p l e d w i t h a l l o f t h e a b o v e a s s u m p t i o n s a n d l i m i t a t i o n s

, t h e r e s u l t s

o f B M P

- S A a r e n o t m e a n t t o r e p l a c e p r o f e s s i o n a l j u d g m e n t i n t h e f i e l d

. R a t h e r

, t h i s t o o l

i s m e a n t t o a s s i s t i n the decision

- m a k i n g p r o c e s s a s s o c i a t e d w i t h f o r e s t r o a d management

a n d p l a n n i n g

. B y i m p l e m e n t i n g a m e t h o d o l o g y a n d / o r t o o l s l i k e t h o s e u s e d h e r e

,

m a n a g e r s c a n i d e n t i f y w h e r e t o f o c u s l i m i t e d r e s o u r c e s t o a c h i e v e t h e g r e a t e s t e c o n o m i c

and environmental benefit across multiple spatial and temporal scales.81 3 .8 R eferences

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we still need to learn? Hydrological Process es 16: 2901

– 2904.

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Oregon

. Water Resources Research 35(8): 2561

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Luce, C.H., and Black, T.A. 2001 a . Spatial and Temporal Patterns in Erosion from Forest

Roads. In I n f l u e n c e o f U r b a n a n d F o r e s t L a n d U s e s o n t h e H y d r o l o g i c

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, E d i t e d b y M

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Monographs, American Geophysical Union, Washington, D.C. pp. 165

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r o a d s e d i m e n t p r o d u c t i o n

. I n P r o c e e d i n g s o f t h e S e v e n t h F e d e r a l I n t e r a g e n c y

Sedimentation Conference, March 25

- 29, 2001, Reno, NV. pp. V67

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Sediments from Forest Roads in Idaho. Water Resources Bulletin 32(2): 371

- 382.

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. E f f e c t s o f L o g g i n g a n d L o g g i n g R o a d s i n E r o s i o n

and Sediment Deposition on Steep Terrain. Journal of Forestry 7: 136

- 141.

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. J o u r n a l o f C h e m i c a l

Physics 21(6): 1087

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R esearch E ngineer. Email c ommunication, September 3, 2008.83 R o b e r t s

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D a i l y L o a d T e c h n i c a l R e p o r t

, C a l i f o r n i a a n d N e v a d a

. C a l i f o r n i a W a t e r Q u a l i t y C o n t r o l

Board, Lahontan Region and Nevada Division of Environmental Protection.

Row, C., Kaiser, H.F., and Sessions, J. 1981. Discount Rate for Long

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Service Investments. Journal of Forestry. 79(6): 367

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Rowe, T.G., Saleh, D.K., Watkins, S.A., Kratzer, C.R., 2002. Stream fl ow andWater

- Quality Data for Selected Watersheds in the Lake Tahoe Basin, California and Nevada,

Through September 1998. Water Reso urces Investigations Report 02

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Geological Survey, Carson City, p. 118 pp.

S c h o e n

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Simon, A., E.J. Langendoen, R.L. Bingner, R. Wells, A. Heins, N. Jokay and I. Jaramillo.

2003. Lake Tahoe Basin Framework Implementation Study: Sediment Loadings and

Channel Erosion. USDA

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39. 3 77 p.

S u g d e n

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Montana. Journal of American Water Resources Association 43(1): 193

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U S D A F o r e s t S e r v i c e : P a c i f i c S o u t h w e s t R e s e a r c h S t a t i o n

. 2 0 0 0

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A s s e s s m e n t

. M u r p h y

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175.

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University of Montana. Personal communication May 2009.

W e m p l e

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L o g g i n g R o a d s i n T w o B a s i n s

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, O r e g o n

. W a t e r R e s o u r c e s B u l l e t i n

32(6): 1195

- 1207.

U S D A F o r e s t S e r v i c e : Intermountain

, S o u t h w e s t

, a n d R o c k y M o u n t a i n R e g i o n s

. 2 008

Cost Estimating Guide for Road Construction.A Appendix es

A. Example Solution from BMP

- SA A lgorithm

Notes about solution:

T h i s i s a r a w s o l u t i o n o u t p u t

. T h e f a c t t h a t t h e s o l u t i o n s t a r t s a t P e r i o d 0 a n d e n d s

a t P e r i o d 1 9 i s a n a r t i f a c t o f a l g o r i t h m p r o g r a m m i n g

, s i n c e a r r a y s s t o r e v a l u e s s t a r t i n g a t

0. Results are correct despite this discrepancy; simply add 1 to each period value.

N o n z e r o v a l u e s f o r p e r i o d s w h e r e t h e r e i s n o i n s t a l l a t i o n o r m a i n t e n a n c e a c t i v ity

i s d u e t o a d d i t i o n a n d s u b t r a c t i o n o f f l o a t i n g p o i n t v a l u e s

. N o t e t h a t

, i n a l l i n s t a n c e s

where this occurs, values are zero to at least the second decimal place.

Pre

- existing BMP codes:

- rld: rock

- lined ditch

- nd: native ditch

- god: gravel on drain dip

________________________________________________________________________

BMP SIMULATED ANNEALING ALGORITHM RESULTS

The best solution has a sediment output over the course of the planning horizon of:

11.512097 tons

Cost of the best solution over the co urse of the planning horizon: 127083.781250 dollars

Initial budget: 57000 .000000 dollars per period

THE SOLUTION:

PERIOD 0

install BMP 3draindips on segment 6 at install cost 300.000000

install BMP outslope on segment 7 at install cost 89.520454

ins tall BMP draindip on segment 31 at install cost 100.000000

install BMP draindip on segment 33 at install cost 100.000000

install BMP outslope on segment 38 at install cost 72.805679

install BMP outslope on segment 41 at install cost 50.951530

install B MP draindip on segment 49 at install cost 100.000000

install BMP draindip on segment 52 at install cost 100.000000

install BMP 3draindips on segment 59 at install cost 300.000000

install BMP draindip on segment 60 at install cost 100.000000

install BMP draindip on segment 62 at install cost 100.000000

install BMP draindip on segment 65 at install cost 100.000000

install BMP draindip on segment 66 at install cost 100.000000

install BMP 3draindips on segment 67 at install cost 300.000000

install B MP draindip on segment 69 at install cost 100.000000

install BMP draindip on segment 71 at install cost 100.000000B install BMP draindip on segment 79 at install cost 100.000000

install BMP draindip on segment 80 at install cost 100.000000

install BMP d raindip on segment 93 at install cost 100.000000

install BMP outslope on segment 95 at install cost 133.189194

install BMP outslope on segment 96 at install cost 122.434662

install BMP outslope on segment 108 at install cost 143.797150

install BMP outs lope on segment 112 at install cost 123.576141

install BMP 3draindips on segment 113 at install cost 300.000000

install BMP draindip on segment 115 at install cost 100.000000

install BMP outslope on segment 116 at install cost 486.000000

install BMP dr aindip on segment 117 at install cost 100.000000

install BMP 7draindips on segment 119 at install cost 700.000000

install BMP draindip on segment 120 at install cost 100.000000

install BMP draindip on segment 121 at install cost 100.000000

install BMP outslope on segment 127 at install cost 1143.000000

install BMP draindip on segment 133 at install cost 100.000000

install BMP draindip on segment 134 at install cost 100.000000

install BMP outslope on segment 136 at install cost 91.398865

install BMP outslope on segment 141 at install cost 47.919949

install BMP outslope on segment 142 at install cost 390.000000

install BMP 7draindips on segment 146 at install cost 700.000000

install BMP draindip on segment 174 at install cost 100.000000

Treatment cost for period 0: 32494.597656 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 1

Treatment cost for period 1: 0.000000 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 2

maintain preexisting BMP rld on segment 66 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 67 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 68 at maintenance cost 94.500000

main tain preexisting BMP rld on segment 70 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 72 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 109 at maintenance cost 94.500000

Treatment cost for period 2:

- 0.00097 7 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 3C maintain BMP outslope on segment 7 at maintenance cost 29.840151

maintain preexisting BMP outsloping on segment 8 at maintenance cost 43.489964

maintain preexisting BMP gravel on segment 32 at maintenance cost 154.104172

maintain preexisting BMP outsloping on segment 32 at maintenance cost 35.023674

maintain preexisting BMP gravel on segment 34 at maintenance cost 34.347500

maintain BMP outslope on segment 38 at maintenance cost 24.268560

maintain BMP outslope on segment 41 at maintenance cost 16.983845

maintain preexisting BMP gravel on segment 42 at maintenance cost 161.444168

maintain preexisting BMP outsloping on segment 50 at main tenance cost 25.320456

maintain preexisting BMP gravel on segment 66 at maintenance cost 175.522491

maintain preexisting BMP gravel on segment 67 at maintenance cost 351.648315

maintain preexisting BMP gravel on segment 68 at maintenance cost 76.655334

maintain preexisting BMP gravel on segment 70 at maintenance cost 112.001663

maintain preexisting BMP gravel on segment 72 at maintenance cost 115.975838

maintain preexisting BMP gravel on segment 80 at maintenance cost 175.290009

maintain preexisting BMP outsloping on segment 81 at maintenance cost 57.188446

maintain preexisting BMP outsloping on segment 94 at maintenance cost 19.917046

maintain BMP outslope on segment 95 at maintenance cost 44.396400

maintain BMP outslope on segment 96 at maintenan ce cost 40.811554

maintain BMP outslope on segment 108 at maintenance cost 47.932384

maintain preexisting BMP gravel on segment 109 at maintenance cost 49.375500

maintain BMP outslope on segment 112 at maintenance cost 41.192047

maintain preexisting BM P gravel on segment 114 at maintenance cost 80.570831

maintain BMP outslope on segment 116 at maintenance cost 162.000000

maintain BMP outslope on segment 127 at maintenance cost 381.000000

maintain preexisting BMP outsloping on segment 135 at maintenan ce cost 185.059280

maintain BMP outslope on segment 136 at maintenance cost 30.466288

maintain preexisting BMP outsloping on segment 138 at maintenance cost 60.063633

maintain BMP outslope on segment 141 at maintenance cost 15.973315

maintain preexisti ng BMP outsloping on segment 143 at maintenance cost 20.971781

maintain BMP outslope on segment 142 at maintenance cost 130.000000

maintain preexisting BMP outsloping on segment 148 at maintenance cost 48.701519

Treatment cost for period 3: 6964.864258 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 4

maintain preexisting BMP nd on segment 34 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 42 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 50 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 53 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 63 at maintenance cost 400.000000

maintain preexisting BMP rld on se gment 66 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 67 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 68 at maintenance cost 94.500000D maintain preexisting BMP rld on segment 70 at maintenance cost 94.50 0000

maintain preexisting BMP rld on segment 72 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 109 at maintenance cost 94.500000

maintain preexisting BMP nd on segment 114 at maintenance cost 400.000000

Treatment cost for period 4: 0.000549 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 5

maintain BMP 3draindips on segment 6 at maintenance cost 300.000000

maintain preexisting BMP dd on segment 8 at maintenance cost 150.00 0000

maintain BMP draindip on segment 31 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 32 at maintenance cost 150.000000

maintain BMP draindip on segment 33 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 3 4 at maintenance cost 150.000000

maintain preexisting BMP dd on segment 42 at maintenance cost 150.000000

maintain BMP draindip on segment 49 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 50 at maintenance cost 150.000000

maintain BMP draindip on segment 52 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 53 at maintenance cost 150.000000

maintain BMP 3draindips on segment 59 at maintenance cost 300.000000

maintain BMP draindip on segment 60 at maint enance cost 100.000000

maintain preexisting BMP dd on segment 61 at maintenance cost 150.000000

maintain BMP draindip on segment 62 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 63 at maintenance cost 150.000000

maintain BMP dra indip on segment 65 at maintenance cost 100.000000

maintain BMP draindip on segment 66 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 67 at maintenance cost 150.000000

maintain BMP 3draindips on segment 67 at maintenance cost 300. 000000

maintain preexisting BMP dd on segment 68 at maintenance cost 150.000000

maintain BMP draindip on segment 69 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 70 at maintenance cost 150.000000

maintain BMP draindip on segment 71 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 72 at maintenance cost 150.000000

maintain BMP draindip on segment 79 at maintenance cost 100.000000

maintain BMP draindip on segment 80 at maintenance cost 100.000000

maintain p reexisting BMP dd on segment 81 at maintenance cost 150.000000

maintain BMP draindip on segment 93 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 94 at maintenance cost 150.000000

maintain BMP 3draindips on segment 113 at maintena nce cost 300.000000

maintain preexisting BMP dd on segment 114 at maintenance cost 150.000000

maintain BMP draindip on segment 115 at maintenance cost 100.000000

maintain BMP draindip on segment 117 at maintenance cost 100.000000

maintain BMP 7draindip s on segment 119 at maintenance cost 700.000000

maintain BMP draindip on segment 120 at maintenance cost 100.000000E maintain BMP draindip on segment 121 at maintenance cost 100.000000

maintain BMP draindip on segment 133 at maintenance cost 100.000000

maintain BMP draindip on segment 134 at maintenance cost 100.000000

maintain BMP 7draindips on segment 146 at maintenance cost 700.000000

maintain BMP draindip on segment 174 at maintenance cost 100.000000

Treatment cost for period 5: 17599.998047 dolla rs

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 6

maintain BMP outslope on segment 7 at maintenance cost 29.840151

maintain preexisting BMP outsloping on segment 8 at maintenance cost 43.489964

maintai n preexisting BMP gravel on segment 32 at maintenance cost 154.104172

maintain preexisting BMP outsloping on segment 32 at maintenance cost 35.023674

maintain preexisting BMP gravel on segment 34 at maintenance cost 34.347500

maintain BMP outslope on se gment 38 at maintenance cost 24.268560

maintain BMP outslope on segment 41 at maintenance cost 16.983845

maintain preexisting BMP gravel on segment 42 at maintenance cost 161.444168

maintain preexisting BMP outsloping on segment 50 at maintenance cost 2 5.320456

maintain preexisting BMP gravel on segment 66 at maintenance cost 175.522491

maintain preexisting BMP rld on segment 66 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 67 at maintenance cost 351.648315

maintain preexis ting BMP rld on segment 67 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 68 at maintenance cost 76.655334

maintain preexisting BMP rld on segment 68 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 70 a t maintenance cost 112.001663

maintain preexisting BMP rld on segment 70 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 72 at maintenance cost 115.975838

maintain preexisting BMP rld on segment 72 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 80 at maintenance cost 175.290009

maintain preexisting BMP outsloping on segment 81 at maintenance cost 57.188446

maintain preexisting BMP outsloping on segment 94 at maintenance cost 19.917046

maintain BMP ou tslope on segment 95 at maintenance cost 44.396400

maintain BMP outslope on segment 96 at maintenance cost 40.811554

maintain BMP outslope on segment 108 at maintenance cost 47.932384

maintain preexisting BMP gravel on segment 109 at maintenance cost 49 .375500

maintain preexisting BMP rld on segment 109 at maintenance cost 94.500000

maintain BMP outslope on segment 112 at maintenance cost 41.192047

maintain preexisting BMP gravel on segment 114 at maintenance cost 80.570831

maintain BMP outslope on s egment 116 at maintenance cost 162.000000

maintain BMP outslope on segment 127 at maintenance cost 381.000000

maintain preexisting BMP outsloping on segment 135 at maintenance cost 185.059280

maintain BMP outslope on segment 136 at maintenance cost 30.4 66288

maintain preexisting BMP outsloping on segment 138 at maintenance cost 60.063633

maintain BMP outslope on segment 141 at maintenance cost 15.973315F maintain preexisting BMP outsloping on segment 143 at maintenance cost 20.971781

maintain BMP outs lope on segment 142 at maintenance cost 130.000000

maintain preexisting BMP outsloping on segment 148 at maintenance cost 48.701519

Treatment cost for period 6: 6964.864746 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 7

Treatment cost for period 7:

- 0.000366 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 8

maintain preexisting BMP nd on segment 34 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 42 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 50 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 53 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 63 at maintenance cost 400.000000

maintain preexisting BMP rld on segment 66 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 67 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 68 at maintenance cost 94.500000

ma intain preexisting BMP rld on segment 70 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 72 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 109 at maintenance cost 94.500000

maintain preexisting BMP nd on segm ent 114 at maintenance cost 400.000000

Treatment cost for period 8: 0.000000 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 9

maintain BMP outslope on segment 7 at maintenance cost 29.840151

main tain preexisting BMP outsloping on segment 8 at maintenance cost 43.489964

maintain preexisting BMP gravel on segment 32 at maintenance cost 154.104172

maintain preexisting BMP outsloping on segment 32 at maintenance cost 35.023674

maintain preexisting BMP gravel on segment 34 at maintenance cost 34.347500

maintain BMP outslope on segment 38 at maintenance cost 24.268560

maintain BMP outslope on segment 41 at maintenance cost 16.983845

maintain preexisting BMP gravel on segment 42 at maintenance cost 161.444168

maintain preexisting BMP outsloping on segment 50 at maintenance cost 25.320456

maintain preexisting BMP gravel on segment 66 at maintenance cost 175.522491

maintain preexisting BMP gr avel on segment 67 at maintenance cost 351.648315

maintain preexisting BMP gravel on segment 68 at maintenance cost 76.655334

maintain preexisting BMP gravel on segment 70 at maintenance cost 112.001663G maintain preexisting BMP gravel on segment 72 at m aintenance cost 115.975838

maintain preexisting BMP gravel on segment 80 at maintenance cost 175.290009

maintain preexisting BMP outsloping on segment 81 at maintenance cost 57.188446

maintain preexisting BMP outsloping on segment 94 at maintenance cost 19.917046

maintain BMP outslope on segment 95 at maintenance cost 44.396400

maintain BMP outslope on segment 96 at maintenance cost 40.811554

maintain BMP outslope on segment 108 at maintenance cost 47.932384

maintain preexisting BMP gravel on segment 109 at maintenance cost 49.375500

maintain BMP outslope on segment 112 at maintenance cost 41.192047

maintain preexisting BMP gravel on segment 114 at maintenance cost 80.570831

maintain BMP outslope on segment 116 at maintenance cost 162.000000

maint ain BMP outslope on segment 127 at maintenance cost 381.000000

maintain preexisting BMP outsloping on segment 135 at maintenance cost 185.059280

maintain BMP outslope on segment 136 at maintenance cost 30.466288

maintain preexisting BMP outsloping on se gment 138 at maintenance cost 60.063633

maintain BMP outslope on segment 141 at maintenance cost 15.973315

maintain preexisting BMP outsloping on segment 143 at maintenance cost 20.971781

maintain BMP outslope on segment 142 at maintenance cost 130.0000 00

maintain preexisting BMP outsloping on segment 148 at maintenance cost 48.701519

Treatment cost for period 9: 6964.864746 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 10

maintain BMP 3draindips on segment 6 at maintenance cost 300.000000

maintain preexisting BMP dd on segment 8 at maintenance cost 150.000000

maintain BMP draindip on segment 31 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 32 at maintenan ce cost 150.000000

maintain BMP draindip on segment 33 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 34 at maintenance cost 150.000000

maintain preexisting BMP dd on segment 42 at maintenance cost 150.000000

maintain BMP draindi p on segment 49 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 50 at maintenance cost 150.000000

maintain BMP draindip on segment 52 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 53 at maintenance cost 150. 000000

maintain BMP 3draindips on segment 59 at maintenance cost 300.000000

maintain BMP draindip on segment 60 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 61 at maintenance cost 150.000000

maintain BMP draindip on segment 62 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 63 at maintenance cost 150.000000

maintain BMP draindip on segment 65 at maintenance cost 100.000000

maintain preexisting BMP rld on segment 66 at maintenance cost 94.500000

maintain BMP draindip on segment 66 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 67 at maintenance cost 150.000000

maintain preexisting BMP rld on segment 67 at maintenance cost 94.500000H maintain BMP 3draindips on segment 67 at mainten ance cost 300.000000

maintain preexisting BMP dd on segment 68 at maintenance cost 150.000000

maintain preexisting BMP rld on segment 68 at maintenance cost 94.500000

maintain BMP draindip on segment 69 at maintenance cost 100.000000

maintain preexisti ng BMP dd on segment 70 at maintenance cost 150.000000

maintain preexisting BMP rld on segment 70 at maintenance cost 94.500000

maintain BMP draindip on segment 71 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 72 at maintenance cost 150.000000

maintain preexisting BMP rld on segment 72 at maintenance cost 94.500000

maintain BMP draindip on segment 79 at maintenance cost 100.000000

maintain BMP draindip on segment 80 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 81 at maintenance cost 150.000000

maintain BMP draindip on segment 93 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 94 at maintenance cost 150.000000

maintain preexisting BMP rld on segment 109 at maintenance cost 94.500000

maintain BMP 3draindips on segment 113 at maintenance cost 300.000000

maintain preexisting BMP dd on segment 114 at maintenance cost 150.000000

maintain BMP draindip on segment 115 at maintenance cost 100.000000

maint ain BMP draindip on segment 117 at maintenance cost 100.000000

maintain BMP 7draindips on segment 119 at maintenance cost 700.000000

maintain BMP draindip on segment 120 at maintenance cost 100.000000

maintain BMP draindip on segment 121 at maintenance cost 100.000000

maintain BMP draindip on segment 133 at maintenance cost 100.000000

maintain BMP draindip on segment 134 at maintenance cost 100.000000

maintain BMP 7draindips on segment 146 at maintenance cost 700.000000

maintain BMP draindip on segme nt 174 at maintenance cost 100.000000

Treatment cost for period 10: 17600.000000 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 11

Treatment cost for period 11:

- 0.000244 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 12

maintain BMP outslope on segment 7 at maintenance cost 29.840151

maintain preexisting BMP outsloping on segment 8 at maintenance cost 43.489964

maintain preexisting BMP gravel on segment 32 at maintenance cost 154.104172

maintain preexisting BMP outsloping on segment 32 at maintenance cost 35.023674

maintain preexisting BMP gravel on segment 34 at maintenance cost 34.347500

maintain preexisting BMP nd on segment 34 at maintenance cost 400.000000

maintain BMP outslope on segment 38 at maintenance cost 24.268560

maintain BMP outslope on segment 41 at maintenance cost 16.983845I maintain preexisting BMP gravel on segment 42 at maintenance cost 161.444168

maintain preexisting BMP nd on segment 42 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 50 at maintenance cost 400.000000

maintain preexisting BMP outsloping on segment 50 at maintenance cost 25.320456

maintain preexisting BMP nd on segment 53 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 63 at maintenance cost 400.000000

maintain preexisting BMP gravel on segment 66 at maintenance cost 175.522491

maintain preexisting BMP rld on segment 66 at maintenan ce cost 94.500000

maintain preexisting BMP gravel on segment 67 at maintenance cost 351.648315

maintain preexisting BMP rld on segment 67 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 68 at maintenance cost 76.655334

maintain preexisting BMP rld on segment 68 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 70 at maintenance cost 112.001663

maintain preexisting BMP rld on segment 70 at maintenance cost 94.500000

maintain preexisting BMP gravel on seg ment 72 at maintenance cost 115.975838

maintain preexisting BMP rld on segment 72 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 80 at maintenance cost 175.290009

maintain preexisting BMP outsloping on segment 81 at maintenance cost 57.188446

maintain preexisting BMP outsloping on segment 94 at maintenance cost 19.917046

maintain BMP outslope on segment 95 at maintenance cost 44.396400

maintain BMP outslope on segment 96 at maintenance cost 40.811554

maintain BMP outslope on segment 108 at maintenance cost 47.932384

maintain preexisting BMP gravel on segment 109 at maintenance cost 49.375500

maintain preexisting BMP rld on segment 109 at maintenance cost 94.500000

maintain BMP outslope on segment 112 at maintenance cost 41.192047

maintain preexisting BMP gravel on segment 114 at maintenance cost 80.570831

maintain preexisting BMP nd on segment 114 at maintenance cost 400.000000

maintain BMP outslope on segment 116 at maintenance cost 162.000000

maintain BMP outslope on segment 127 at maintenance cost 381.000000

maintain preexisting BMP outsloping on segment 135 at maintenance cost 185.059280

maintain BMP outslope on segment 136 at maintenance cost 30.466288

maintain preexisting BMP outsloping on segment 138 at main tenance cost 60.063633

maintain BMP outslope on segment 141 at maintenance cost 15.973315

maintain preexisting BMP outsloping on segment 143 at maintenance cost 20.971781

maintain BMP outslope on segment 142 at maintenance cost 130.000000

maintain pree xisting BMP outsloping on segment 148 at maintenance cost 48.701519

Treatment cost for period 12: 6964.864258 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 13

Treatment cost for period 13:

- 0.001 923 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment costJ PERIOD 14

maintain preexisting BMP rld on segment 66 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 67 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 68 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 70 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 72 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 109 at maintenance cost 94.500000

Treatment cost for period 14:

- 0.002686 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 15

maintain BMP 3draind ips on segment 6 at maintenance cost 300.000000

maintain BMP outslope on segment 7 at maintenance cost 29.840151

maintain preexisting BMP dd on segment 8 at maintenance cost 150.000000

maintain preexisting BMP outsloping on segment 8 at maintenance cost 43.489964

maintain BMP draindip on segment 31 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 32 at maintenance cost 150.000000

maintain preexisting BMP gravel on segment 32 at maintenance cost 154.104172

maintain preexisting BMP outsloping on segment 32 at maintenance cost 35.023674

maintain BMP draindip on segment 33 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 34 at maintenance cost 150.000000

maintain preexisting BMP gravel on segment 34 at maintena nce cost 34.347500

maintain BMP outslope on segment 38 at maintenance cost 24.268560

maintain BMP outslope on segment 41 at maintenance cost 16.983845

maintain preexisting BMP dd on segment 42 at maintenance cost 150.000000

maintain preexisting BMP gra vel on segment 42 at maintenance cost 161.444168

maintain BMP draindip on segment 49 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 50 at maintenance cost 150.000000

maintain preexisting BMP outsloping on segment 50 at maintenance cost 25.320456

maintain BMP draindip on segment 52 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 53 at maintenance cost 150.000000

maintain BMP 3draindips on segment 59 at maintenance cost 300.000000

maintain BMP draindip on segment 60 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 61 at maintenance cost 150.000000

maintain BMP draindip on segment 62 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 63 at maintenance cost 150.000000

maintain BMP draindip on segment 65 at maintenance cost 100.000000

maintain preexisting BMP gravel on segment 66 at maintenance cost 175.522491

maintain BMP draindip on segment 66 at maintenance cost 100.000000

maintain pre existing BMP dd on segment 67 at maintenance cost 150.000000

maintain preexisting BMP gravel on segment 67 at maintenance cost 351.648315

maintain BMP 3draindips on segment 67 at maintenance cost 300.000000

maintain preexisting BMP dd on segment 68 at m aintenance cost 150.000000K maintain preexisting BMP gravel on segment 68 at maintenance cost 76.655334

maintain BMP draindip on segment 69 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 70 at maintenance cost 150.000000

maintain preexisting BMP gravel on segment 70 at maintenance cost 112.001663

maintain BMP draindip on segment 71 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 72 at maintenance cost 150.000000

maintain preexisting BMP gravel on segment 72 at maintenance cost 115.975838

maintain BMP draindip on segment 79 at maintenance cost 100.000000

maintain preexisting BMP gravel on segment 80 at maintenance cost 175.290009

maintain BMP draindip on segment 80 at maintenance cost 100.000000

maintain preexisting BMP dd on segment 81 at maintenance cost 150.000000

maintain preexisting BMP outsloping on segment 81 at maintenance cost 57.188446

maintain BMP draindip on segment 93 at maintenance cost 100.000000

maintain preexisting BMP outsloping on segment 94 at maintenance cost 19.917046

maintain preexisting BMP dd on segment 94 at maintenance cost 150.000000

maintain BMP outslope on segment 95 at maintenance cost 44.396400

maintain BMP outslope on segment 96 at maintenance cost 40.811554

ma intain BMP outslope on segment 108 at maintenance cost 47.932384

maintain preexisting BMP gravel on segment 109 at maintenance cost 49.375500

maintain BMP outslope on segment 112 at maintenance cost 41.192047

maintain BMP 3draindips on segment 113 at ma intenance cost 300.000000

maintain preexisting BMP dd on segment 114 at maintenance cost 150.000000

maintain preexisting BMP gravel on segment 114 at maintenance cost 80.570831

maintain BMP draindip on segment 115 at maintenance cost 100.000000

maintai n BMP outslope on segment 116 at maintenance cost 162.000000

maintain BMP draindip on segment 117 at maintenance cost 100.000000

maintain BMP 7draindips on segment 119 at maintenance cost 700.000000

maintain BMP draindip on segment 120 at maintenance co st 100.000000

maintain BMP draindip on segment 121 at maintenance cost 100.000000

maintain BMP outslope on segment 127 at maintenance cost 381.000000

maintain BMP draindip on segment 133 at maintenance cost 100.000000

maintain preexisting BMP outslopin g on segment 135 at maintenance cost 185.059280

maintain BMP draindip on segment 134 at maintenance cost 100.000000

maintain BMP outslope on segment 136 at maintenance cost 30.466288

maintain preexisting BMP outsloping on segment 138 at maintenance cost 60.063633

maintain BMP outslope on segment 141 at maintenance cost 15.973315

maintain preexisting BMP outsloping on segment 143 at maintenance cost 20.971781

maintain BMP outslope on segment 142 at maintenance cost 130.000000

maintain BMP 7draindips o n segment 146 at maintenance cost 700.000000

maintain preexisting BMP outsloping on segment 148 at maintenance cost 48.701519

maintain BMP draindip on segment 174 at maintenance cost 100.000000

Treatment cost for period 15: 24564.867188 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 16L maintain preexisting BMP nd on segment 34 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 42 at maintenance cost 400.000000

maintain pree xisting BMP nd on segment 50 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 53 at maintenance cost 400.000000

maintain preexisting BMP nd on segment 63 at maintenance cost 400.000000

maintain preexisting BMP rld on segment 66 at m aintenance cost 94.500000

maintain preexisting BMP rld on segment 67 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 68 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 70 at maintenance cost 94.500000

maintai n preexisting BMP rld on segment 72 at maintenance cost 94.500000

maintain preexisting BMP rld on segment 109 at maintenance cost 94.500000

maintain preexisting BMP nd on segment 114 at maintenance cost 400.000000

Treatment cost for period 16:

- 0.001190 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 17

Treatment cost for period 17:

- 0.000977 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 18

maintain BMP outslope on segment 7 at maintenance cost 29.840151

maintain preexisting BMP outsloping on segment 8 at maintenance cost 43.489964

maintain preexisting BMP gravel on segment 32 at maintenance cost 154.104172

maintain preexisting BMP outsloping on segment 32 at maintenance cost 35.023674

maintain preexisting BMP gravel on segment 34 at maintenance cost 34.347500

maintain BMP outslope on segment 38 at maintenance cost 24.268560

maintain BMP outslope on segment 41 at maintenance cost 16.983845

maintain preexisting BMP gravel on segment 42 at maintenance cost 161.444168

maintain preexisting BMP outsloping on segment 50 at maintenance cost 25.320456

maintain preexisting BMP gravel on segment 66 at maintenance cost 175.522491

maintain preexisting BMP rld on segment 66 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 67 at maintenance cost 351.648315

maintain preexisting BMP rld on segment 67 at maintenance cost 94.500000

maintain preexisting BMP gravel on seg ment 68 at maintenance cost 76.655334

maintain preexisting BMP rld on segment 68 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 70 at maintenance cost 112.001663

maintain preexisting BMP rld on segment 70 at maintenance cost 94 .500000

maintain preexisting BMP gravel on segment 72 at maintenance cost 115.975838

maintain preexisting BMP rld on segment 72 at maintenance cost 94.500000

maintain preexisting BMP gravel on segment 80 at maintenance cost 175.290009

maintain preexist ing BMP outsloping on segment 81 at maintenance cost 57.188446M maintain preexisting BMP outsloping on segment 94 at maintenance cost 19.917046

maintain BMP outslope on segment 95 at maintenance cost 44.396400

maintain BMP outslope on segment 96 at maint enance cost 40.811554

maintain BMP outslope on segment 108 at maintenance cost 47.932384

maintain preexisting BMP gravel on segment 109 at maintenance cost 49.375500

maintain preexisting BMP rld on segment 109 at maintenance cost 94.500000

maintain BMP outslope on segment 112 at maintenance cost 41.192047

maintain preexisting BMP gravel on segment 114 at maintenance cost 80.570831

maintain BMP outslope on segment 116 at maintenance cost 162.000000

maintain BMP outslope on segment 127 at maintenance cost 381.000000

maintain preexisting BMP outsloping on segment 135 at maintenance cost 185.059280

maintain BMP outslope on segment 136 at maintenance cost 30.466288

maintain preexisting BMP outsloping on segment 138 at mai ntenance cost 60.063633

maintain BMP outslope on segment 141 at maintenance cost 15.973315

maintain preexisting BMP outsloping on segment 143 at maintenance cost 20.971781

maintain BMP outslope on segment 142 at maintenance cost 130.000000

maintain pre existing BMP outsloping on segment 148 at maintenance cost 48.701519

Treatment cost for period 18: 6964.863281 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment cost

PERIOD 19

Treatment cost for period 19: 0.001 938 dollars

NOTE: preexisting BMP cost already accounted for, so it won't show up in treatment costN B. Flowchart Describing Adapted Simulated Annealing Algorithm

No Ye No

Stop, report best solution Lower temperature Time to change

temperature?

Have stopping criteria

been reached? Ye

s No

Ye

s Input initial budget per period, length of

planning horizon; Define initial temperature

Compute cost of maintaining existing

BMPs over course of planning horizon,

subtract from initial budget

Develop initial (current) solution, including maintenance regime

Formulate new solution and maintenance

regime: change BMP or period of

installation for one road segment in current

s olution

Compute sediment leaving buffer over

course of planning horizon for

each solution Compute proximity between segments

Compute acceptance probability Does the new solution save

more sediment than the current

solution?

Go to next iteration; update

current solution N

o

Ye

s Accept solution?O C . Example Input Table for BMP

- SA A lgorithm

segment number BMP type installation cost maintenance cost maintenance frequency sediment leaving buffer

_______________________________________________________________________

6 none 0 0 0 0 draindip 100 100 5 0.001 outslope 128.4272706 42.8090902

3 0 3draindips 300 300 5 0

7 n one 0 0 0 0 draindip 100 100 5 0 outslope 89.52045294 29.84015098

3 0 none 0 0 0 0

31 none 0 0 0 0 draindip 100 100 5 0.001 none 0 0 0 0 none

0 0 0 0

33 none 0 0 0 0 draindip 100 100 5 0.002 none 0 0 0 0 none

0 0 0 0

38 none 0 0 0 0 outslope 72.80567942 24 .2685598 3 0.005 none 0 0 0

0 none 0 0 0 0

41 none 0 0 0 0 outslope 50.95153236 16.98384412 3 0 none 0 0 0

0 none 0 0 0 0

49 none 0 0 0 0 draindip 100 100 5 0 outslope 210.00 70.00 3 0

none 0 0 0 0

52 none 0 0 0 0 draindip 100 100 5 0 pave 14494.16309 887. 397766 7

0.012 outslope 177.00 59.00 3 0

59 none 0 0 0 0 draindip 100 100 5 0.023 outslope 399.00 133.00 3 0

3draindips 300 300 5 0

60 none 0 0 0 0 draindip 100 100 5 0 outslope 171.00 57.00 3 0

none 0 0 0 0

62 none 0 0 0 0 draindip 100 100 5 0 outslope 471.00 157.00 3 0

none 0 0 0 0

65 none 0 0 0 0 draindip 100 100 5 0.001 none 0 0 0 0 none

0 0 0 0

66 none 0 0 0 0 draindip 100 100 5 0.012 none 0 0 0 0 none

0 0 0 0P 67 none 0 0 0 0 draindip 100 100 5 0.04 3draindips 300 300 5 0.009

none 0 0 0 0

69 none 0 0 0 0 draindip 100 100 5 0.034 none 0 0 0 0 pave

7479.089355 457.903442 7 0.2115

71 none 0 0 0 0 draindip 100 100 5 0.026 pave 7758.704102 475.022705 7

0.1355 none 0 0 0 0

79 none 0 0 0 0 draindip 100 100 5 0 none 0 0 0 0 none

0 0 0 0

80 none 0 0 0 0 draind ip 100 100 5 0.008 none 0 0 0 0 none

0 0 0 0

93 none 0 0 0 0 draindip 100 100 5 0.022 none 0 0 0 0 none

0 0 0 0

95 none 0 0 0 0 draindip 100 100 5 0.024 outslope 133.1892 44.3964

3 0.0065 none 0 0 0 0

96 none 0 0 0 0 draindip 100 100 5 0.025 outslope 122.4 346618 40.81155392

3 0.009 none 0 0 0 0

108 none 0 0 0 0 draindip 100 100 5 0.021 outslope 143.7971559 47.93238529

3 0.001 none 0 0 0 0

112 none 0 0 0 0 draindip 100 100 5 0.017 outslope 123.5761412 41.19204706

3 0.001 none 0 0 0 0

113 none 0 0 0 0 draindi p 100 100 5 0.063 3draindips 300 300 5 0.016

none 0 0 0 0

115 none 0 0 0 0 draindip 100 100 5 0 none 0 0 0 0 none

0 0 0 0

116 none 0 0 0 0 draindip 100 100 5 0 outslope 486.00 162.00 3 0

none 0 0 0 0

117 none 0 0 0 0 draindip 100 100 5 0 outslope 354.00 11 8.00 3 0

none 0 0 0 0

119 none 0 0 0 0 pave 46355.11 2835 7 0.933 3draindips 300 300 5 0.009

7draindips 700 700 5 0Q 120 none 0 0 0 0 draindip 100 100 5 0 none 0 0 0 0 none

0 0 0 0

121 none 0 0 0 0 draindip 100 100 5 0 outslope 294.00 98.00 3 0

none 0 0 0 0

127 none 0 0 0 0 draindip 100 100 5 0.001 outslope 1143.00 381.00 3

0 none 0 0 0 0

133 none 0 0 0 0 draindip 100 100 5 0 pave 23765.00 1440.00 7

0.024 none 0 0 0 0

134 none 0 0 0 0 draindip 100 100 5 0 none 0 0 0 0 none

0 0 0 0

136 none 0 0 0 0 draindip 1 00 100 5 0.017 outslope 91.39886177 30.46628725

3 0.004 none 0 0 0 0

141 none 0 0 0 0 outslope 47.91994706 15.97331569 3 0 none 0 0 0

0 none 0 0 0 0

142 none 0 0 0 0 outslope 390.00 130.00 3 0.0045 3draindips 300 300 5 0.09

7draindips 700 700 5 0.028

146 n one 0 0 0 0 draindip 100 100 5 0.117 3draindips 300 300 5 0.03

7draindips 700 700 5 0.004

174 none 0 0 0 0 draindip 100 100 5 0 none 0 0 0 0 none

0 0 0 0