**A Mini-Workshop on "Development of a Comprehensive Forest Nutrient
Cycle & Export Modeling Package"**

![](media/image1.png){width="0.90625in" height="0.6979166666666666in"}

United States Department of Agriculture

Forest Service

Center for Forested Wetland Research

Santee Experimental Forest

3734 Highway 402

Cordesville, South Carolina 29434

March 6-7, 2008

**A Mini-Workshop on "Development of a Comprehensive Forest Nutrient
Cycle & Export Modeling Package",**

US Forest Service, Santee Experimental Forest, Cordesville, SC

March 6-7, 2008

1.  Welcome -- C.C. Trettin

2.  Preface -- D.M. Amatya and C.C. Trettin

3.  Participants Contact List

4.  Final Workshop Agenda

5.  Abstracts

> 5.1. Terrestrial Process and Fertilizer N Fate in Southern Pine
> Plantation: Needs
>
> for Research and Modeling -- E. Vance
>
> 5.2 Nutrient Fate in Southern Riparian Forests: Research Needs --
>
> E. Schilling
>
> 5.3 DRAINMOD: A Field-Scale Model for Simulating Hydrology and Water
>
> Quality for Shallow Water Table Soils -- M. Youssef/ W. Skaggs
>
> 5.4 DRAINMOD Based Models for Poorly Drained Watersheds -
>
> G. Chescheir/ W. Skaggs
>
> 5.5 Application APEX for Forestry -- A. Saleh
>
> 5.6 SWAT -- C. G. Rossi
>
> 5.7 Applications of the MIKE-SHE model in Forested Watershed in the
>
> Southeastern United States -- G. Sun
>
> 5.8 Forest-DNDC -- A Process-Based Biogeochemical Model - Z. Dai
>
> 5.9 REMM: Riparian Ecosystem Management Model -- R. Williams
>
> 5.10 Lessons on Forest Watersheds and Nutrients with an Emphasis on
> Western
>
> US Studies -- G. Ice
>
> 5.11 Long-term data for Modeling in SE -- D. Amatya and C. Trettin

**March 05, 2008**

**Welcome**

Dear workshop participants,

The enthusiasm for this workshop is reflected in the willing response
for your participation and contributions to the program; so thank you,
and welcome! While we have set a lofty goal for considering a common
initiative for developing a robust simulation framework for assessing
nitrogen dynamics in managed forests, the real value will come from the
discussions and interactions during the workshop. We're pleased to
provide the forum, as it's fitting that a facility, which has
contributed to forest hydrology science over the past 40 years provide
the basis for initiatives to address the contemporary issues of the next
40 years. Thank you!

Carl Trettin, Ph.D.

Team Leader/Soil Scientist,

USDA Forest Service

SRS-4353, Center for Forested Wetlands Research

Santee Experimental Forest,

Cordesville, SC

**PREFACE**

Forests of the Southeastern coastal are generally productive, when
properly managed for soil, water, and nutrients. Nutrient management is
usually required to maximize tree productivity. These forest lands also
provide important ecosystem services that need to be considered in any
management prescription. Nitrogen (N) fertilizer is typically applied to
increase productivity of intensively managed forests in the eastern US,
and phosphorus (P) is also commonly used in the lower coastal plain.
While the majority of the applied N remains in the soil -- plant system,
there are concerns that losses due to leaching could degrade surface
water quality (i.e. maintaining the stream water chemistry, for that
matter the TMDLs). The silvicultural prescription should also ensure the
integrity of the quantity and quality of water draining from these
lands. Accordingly, land managers are increasingly interested in
understanding the mechanisms controlling N fate (amount and forms of
uptake, retention, volatilization, and export in drainage waters (e.g.
in various phases like soil, water, aboveground and belowground biomass)
and their mechanisms etc.) in these forested lands in order to increase
N fertilizer use efficiency and productivity. Most fertilizer fate
studies have been conducted at the plot-scale with no basis for
assessing the fate of fertilizer N that may have been measured in the
soil water. Correspondingly, catchment-scale studies that have measured
stream water quality from N-fertilized stands have not typically
measured different components of the N balance with sufficient
resolution to assess the mechanisms controlling N cycling in forested
ecosystems. No studies have attempted to combine the two approaches
(Binkley et al. 1999), presumably because of the difficulties and
expenses associated with them.

A major limitation of the plot scale research has been the inadequate
consideration of the hydrologic cycle when attempting to address losses.
Correspondingly, many of the nutrient cycle models inadequately consider
the hydrologic budget and flow paths when attempting to address off-site
movement of applied nutrients on a watershed-scale. Because of the
challenges of the large-scale watershed studies, and the myriad of
factors that need to be considered in this scale, the application of
process based models is a means for integrated assessments. A wide range
of models have been developed to simulate and understand the N fate and
transport mechanisms at different spatial and temporal scales, in both
agricultural and forested ecosystems (Li et al., 2004; Styczen and
Storm, 1993; Lunn et al., 1996; El-Kadi and Ling, 1999; Gusman et al.,
1999; Ling and El-Kadi, 1998; Breve, et al., 1997a; 1997b; Youssef et
al., 2005a; 2005b; Fernandez et al., 2005; 2006; 2007; Amatya et al.,
2004; Gassman et al., 2007; Lowrance et al., 2000; Inamdar et al., 2005;
Saleh et al., 2000; Santhi et al., 2001; Pohlert et al., 2007; Stewart
et al., 2006; Styszen and Storm, 1993; Birkinshaw and Ewen, 2000). Each
of these models has strengths, but none are likely sufficiently robust
for general application across the uplands and poorly drained coastal
plains. A brief overview of models (SWAT, APEX coupled with SWAT
(SWAPP), DRAINMOD-NII and its watershed-scale version, MIKE-SHE, DNDC,
and REMM) that we consider to have particular merit during the workshop
are included here as abstracts followed by a tabular information.

**Workshop Objective**

The goal of this workshop is to share current state-of-the-knowledge and
consider the strengths and limitations of each of these models and
discuss whether development of a comprehensive modeling package for both
the uplands and lowlands, including BMPs, is feasible, and if so to
explore a potential approach and outline its details. The needed
organization and collaboration for such an effort, if deemed
appropriate, and work to secure funding through the USDA-NRI or NSF
grants or other similar agencies will also be discussed.

The workshop is hosting the modeling teams who are actively involved in
development, modification, testing, and application of the above models
to come together to brainstorm ideas for feasibility and potential
development of a comprehensive modeling package for simulating
biogeochemical cycling, particularly the nutrient fate and transport in
forest ecosystem.

With initial discussions with NCASI, Weyerhaeuser, and NC State
scientists, Devendra Amatya contacted the principals involved with the
models described above in October, 2007, and broached the idea of the
workshop. There was enthusiasm and consensus on the merits of the idea,
and each person stated that they were willing to participate.
Accordingly, the workshop was planned and scheduled.

A contact list of all workshop participants (both invited
speakers/modeling leaders, observers, and support staff) is also
attached at the end of the proceedings.

**Workshop Hosts:**

Devendra M Amatya, Ph.D., P.E., Research Hydrologist,
(<damatya@fs.fed.us>; 843-336-5612),

Carl Trettin, Ph.D., Research Soil Scientist (<ctrettin@fs.fed.us>;
843-336-5602)

Center for Forested Wetlands Research

USDA Forest Service, Santee Experimental Forest

3734 Highway 402,

Cordesville, SC 29434

**Workshop Sponsors:**

Dr. Jami E Nettles, PhD

Program Manager

Weyerhaeuser Co., Columbus, MS

Dr. Eric Vance, PhD

Manager, Forest Productivity Research

NCASI, Inc., RTP, NC

**A Mini-Workshop on "Development of a Comprehensive Forest Nutrient
Cycle & Export Modeling Package",**

US Forest Service, Santee Experimental Forest, Cordesville, SC

March 6-7, 2008

1\. **Amatya, Dr. Devendra M. (Host Coordinator/Speaker)**

Research Hydrologist

USDA Forest Service, SRS-4353

3734 Highway 402,

Cordesville, SC 29434

Tel: 843-336-5612

Fax: 843-336-5068

Email: [damatya@fs.fed.us](mailto:ctrettin@fs.fed.us)

2\. **Arnold, Dr. Jeff (Speaker - Not attending)**

Hydraulic Engineer

Grassland, Soil & Water Research Laboratory, USDA-ARS

808 East Blackland Road

Temple, TX 76502

Tel: 254-770-6502

Fax: 254-770-6561

Email: <jgarnold@spa.ars.usda.gov>

3\. **Bosch, Dr. David (Speaker -- Not attending)**

Research Engineer

USDA-ARS-SEWRL

2375 Rainwater Road

Tifton, GA 31794

Tel: 229-386-3899

Fax: 229-386-7294

Email: <David.Bosch@ars.usda.gov>

4\. **Chescheir, Dr. George ("Chip") M (Speaker)**

Research Assistant Professor

Biological & Agricultural Engineering Department,

Box 7625, North Carolina State University,

Raleigh, NC 27695-7625.

Tel: 919-515-6741 (615-438-7739 (cell))

Fax: 919-515-7760

Email: <cheschei@eos.ncsu.edu>

5\. **Dai, Dr. Zhaohua (Speaker)**

Research Scientist

University of New Hampshire

USDA Forest Service, SRS-4353

3734 Highway 402,

Cordesville, SC 29434

Tel: 843-336-5606

Fax: 843-336-5068

Email: [zdai@fs.fed.us](mailto:ctrettin@fs.fed.us)

6\. **Edwards, Amy (Participant/Support staff)**

Hydrologic Technician

USDA Forest Service, SRS-4353 (New) (4103- old)

3734 Highway 402,

Cordesville, SC 29434

Tel: 843-336-5608

Fax: 843-336-5068

Email: <aeedwards@fs.fed.us>

7\. **Grace, Dr. Johnny M III (Participant - Not attending)**

Research Engineer

USDA Forest Service, Southern Research Station

520 Duvall Drive,

Auburn, AL 36849.

Tel: 334-826-8700

Fax: 334-821-0037

Email: [jmgrace@fs.fed.us](mailto:rmradeck@cyf-kr.edu.pl)

8\. **Harrison, Andy (Participant/Support staff)**

Hydrologic Technician

USDA Forest Service, SRS-4353 (New) (4103- old)

3734 Highway 402,

Cordesville, SC 29434

Tel: 843-336-5603

Fax: 843-336-5068

Email: [caharrison@fs.fed.us](mailto:aeedwards@fs.fed.us)

9\. **Ice, Dr. George (Speaker)**

Program Manager

NCASI, Inc.

P.O. Box 458

Corvallis, OR 97339

Tel: 541-752-8801

Fax: 541-752-8806

Email: <GIce@wcrc-ncasi.org>

10\. **Hyunwoo, Kim (Participant)\
** Visiting Scholar from Korea\
USDA Forest Service, SRS-4353

3734 Highway 402,

Cordesville, SC 29434

Tel: 843-336-4868

Fax: 843-336-5068

Email: <kim20026@gmail.com>

11\. **Li, Dr. Harbin (Participant)**

Research Ecologist

USDA Forest Service, SRS-4353 (New) (4103- old)

3734 Highway 402,

Cordesville, SC 29434

Tel: 843-336-5604

Fax: 843-336-5068

Email: [hli@fs.fed.us](mailto:ctrettin@fs.fed.us)

12\. **Lockwood, Juanita (Support Staff)**

Support Services Specialist

USDA Forest Service, SRS-4353 (New) (4103- old)

3734 Highway 402,

Cordesville, SC 29434

Tel: 843-336-5601

Fax: 843-336-5068

Email: <jjlockwood@fs.fed.us>

13\. **Lowrance, Dr. Richard (Not attending)**

Ecologist

USDA-ARS-SEWRL

2316 Rainwater Road, Room 3

Tifton, GA 31793

Tel: 229-386-3894

Fax: 229-386-7294

Email: [richard.lowrance@ars.usda.gov](mailto:David.Bosch@ars.usda.gov)

14\. **Nettles, Dr. Jami (Speaker/Cosponsor)**\
Program Manager/Hydrologist

Weyerhaeuser Company

P.O. Box 2288

Columbus, MS 39704-2288

Tel: 662-245-5226

Fax: 662-245-5228

Email:
[jami.nettles@weyerhaeuser.com](mailto:peter.farnum@weyerhaeuser.com)

15\. **Rossi, Dr. C. Green (Speaker)**

Research Scientist

Grassland Soil and Water Research Laboratory

808 E. Blackland Rd.

Temple, TX 76502

Tel: 254-770-6507

Fax: 254-770-6561

Email: <cole.rossi@ars.usda.gov>

16\. **Saleh, Dr. Ali (Speaker)**

Research Scientist

Texas Institute for Applied Environmental Research

P.O. Box T410

Tarleton State University

Stephenville, TX 76402

Tel: 254-968-9799

Fax: 254-968-9790

Email: <saleh@tiaer.tarleton.edu>

17\. **Schilling, Dr. Erik B. (Speaker)**

Senior Research Scientist

National Council for Air and Stream Improvement, (NCASI), Inc.

Southern Regional center

402 SW 140^th^ Terrace

Newberry, Fl 32669.

Tel: 352-331-1745 (229)\
Fax: 352-331-1766\
Email: <eschilling@src-ncasi.org>

18\. **Skaggs, Dr. R. Wayne (Speaker)**

W.N.R. & Distinguished University Professor

Biological & Agricultural Engineering Department,

Box 7625, North Carolina State University,

Raleigh, NC 27695-7625.

Tel: 919-515-6739

Fax: 919-515-7760

Email: <wayne_skaggs@ncsu.edu>

19\. **Sun, Dr. Ge (Speaker)**\
Research Hydrologist

Southern Global Change Program,

SRS, USDA Forest Service

SGCP-920 Main Campus Drive,

Venture II, Suite 300, Raleigh, NC 27606

Tel: 919-515-9498

Fax: 919-513-2978

Email: gsun@fs.fed.us

20\. **Trettin, Dr. Carl C. (Host Sponsor/Speaker)\
** Team Leader

USDA Forest Service, SRS-4353

3734 Highway 402,

Cordesville, SC 29434

Tel: 843-336-5602

Fax: 843-336-5068

Email: <ctrettin@fs.fed.us>

21\. **Vance, Dr. Eric D. (Speaker/Cosponsor)**

Manager, Forest Carbon Cycle & Productivity

NCASI, Inc.

Research Triangle Park, NC 27708

Tel: 919-558-1999

Fax: 919-558-1998

Email: <EVance@ncasi.org>

22\. **Williams, Randall (Speaker)**

Agricultural Engineer

USDA-ARS-SEWRL

2375 Rainwater Road

Tifton, GA 31794

Tel: 229-386-3895

Fax: 229-386-7294

Email: <randy.williams@ars.usda.gov>

23\. **Williams, Dr. Thomas M (Participant)\
**Professor of Forestry\
Bell Baruch Institute of Coastal Ecology and Forest Science

P.O. Box 596

Georgetown, SC 29442

Tel: 843-546-6318

Fax: 843-546-6296

Email: <tmwllms@clemson.edu>

24\. **Youssef, Dr. Mohamed (Speaker)**

Assistant Professor,\
Biological & Agricultural Engineering Department,

Box 7625, North Carolina State University,

Raleigh, NC 27695-7625.

Tel: 919-515-6717

Fax: 919-515-7760

Email: <Mohamed_Youssef@ncsu.edu>

# 

# Tentative Final Agenda for the March 6-7, 2008 Modeling Mini-Workshop

## Thursday, March 06, 2008

[14:00 -- 15:45 PM]{.underline}

-   Welcome and FS CFWR perspectives on Forest
    Eco-Hydrologic/Biogeochemical Cycling Research (Trettin) -- 5 min

-   Workshop Background, Logistics and Participants' Introduction
    (Amatya) -- 10 min

-   Forest Nutrient Issues in the East (Nettles/Vance/Schilling) -- 30
    min

-   DRAINMOD-NII (Skaggs/Youssef) -- 30 min

-   DRAINMOD-NII-Watershed-scale (Skaggs/Chescheir) -- 30 min

[15:45 -- 16:00 PM]{.underline} -- Break

[16:00 -- 18:00 PM]{.underline}

-   SWAPP: SWAT+APEX (Saleh) -- 30 min

-   SWAT Hydrology & Nutrient Cycling (Rossi) -- 30 min

-   MIKE-SHE (Sun) -- 30 min

-   DNDC (Dai) -- 30 min

[18:00 PM]{.underline} onwards -- Dinner on your own

# Friday, March 7:

[8:30 -- 10:15 AM]{.underline}

-   REMM (Williams) -- 30 min

-   Forest Nutrient Issues in the West (Ice) -- 30 min

-   Long-term data sets for Modeling (Amatya) -- 15 min

-   Discussions on models, questions/answers on all models (Moderator:
    Amatya) -- 30 min

10:15 -- 10:30 -- Coffee break

[10:30 AM]{.underline} --[12:30 PM- Brainstorming session -- Facilitator
(Trettin)]{.underline}

-   "Where do we go from here? What are the strengths in each model that
    can be linked with other models? What modifications/improvements
    could be done to enhance the predictive capability? Where linkages
    can be made with each other? Is it possible, practical and
    cost-effective for users or beneficiaries like NCASI, Weyerhaeuser,
    and other forest industries/land managers/regulators/researchers to
    "Develop a more Comprehensive Watershed-scale Eco-hydrological
    Model" (includes hydrology, in-stream, biogeochemical and nutrients
    for uplands and lowlands) by a multi-collaboration, if and when such
    an opportunity becomes available? If so, who would be willing to
    lead such an effort and how?

[12:30 -- 13:30 PM]{.underline} -- Lunch (Provided)

[13:30-13:50 PM]{.underline}

-   Synthesis and resolution/recommendation (Skaggs/Amatya)-- 10 min

-   Industries' Remarks (If needed, Who ??) -- 5 min

-   Note of Thanks (Trettin) -- 5 min

[13:50 -- 15:00 PM]{.underline}

-   An optional tour of Santee experimental watersheds (Amatya/Harrison)

[15:00 PM]{.underline}- An option for participants to spend time on
Friday evening and weekend in beautiful historic Charleston. ***Thank
you for your participation and Have a Safe Trip!!!***

**Terrestrial Processes and Fertilizer N Fate in Southern Pine
Plantations:**

**Needs for Research and Modeling**

Eric D. Vance

National Council for Air and Stream Improvement (NCASI)

Research Triangle Park, NC

Evidence suggests that forest fertilization is a minor contributor to
water and air quality impairment, particularly when considered in the
context of other land uses. The extent and intensity of forest
fertilizer use could increase in the future, however, if more productive
forests are needed to meet demands for traditional products or emerging
markets for energy and biomaterials. Southern pine plantations, in
particular, could be relied upon to meet an increasing share of the
nation's fiber needs. Understanding the fate of fertilizer nitrogen and
its potential environmental impacts is particularly complex due to a
wide range of abiotic and biotic factors affecting its forms and
movement.

There have been many terrestrial N cycling studies in pine plantations
but relatively few have comprehensively addressed linkages between
terrestrial processes and the ultimate fate of fertilizer N. Because of
the high cost and complexity of such studies, most have instead focused
on particular system components, have missed windows where N fluxes are
particularly high, and have not been designed to directly trace the fate
of applied N. Because the current suite of studies is inadequate,
additional data and models are needed to begin to project fertilizer N
fate across a range of sites and practices. Once validated, outputs from
such models can be used in the development of general fertilizer
guidelines for resource managers and can help document how fertilizer
can be safely and effectively used at the stand and landscape scales.

**Nutrient Fate in Southern Riparian Forests: Research Needs**

Erik B. Schilling

Senior Research Scientist

National Council for Air and Stream Improvement, Inc.

Southern Regional Center

402 SW 140^th^ Terrace

Newberry, FL 32669-3000

Watersheds that possess high amounts of forest cover often have the
highest water quality compared to those watersheds dominated by other
land uses. While relationships between forests and indices of water
quality are well documented, questions still remain regarding the impact
of silvicultural activities on water resources. This is particularly
evident with regard to non-point source pollution (i.e., sediment,
nutrients, and herbicides) even though voluntary forestry Best
Management Practices (BMPs) have been repeatedly demonstrated to
effectively reduce anthropogenic disturbances to water resources in the
eastern United States. However, concerns still exist about the
influences of forest management and are manifested in the development of
Total Maximum Daily Load allocations and attempts to reclassify forestry
management activities, which include use of fertilizers and herbicides,
as point sources of pollution subject to National Pollution Discharge
Elimination System permits.

While an overwhelming number of studies monitoring the effectiveness of
forestry BMPs on water resources have reported positive results, some
critical issues are still prevalent, particularly for those management
prescriptions utilized in riparian forests. Concerns over management of
riparian forests and the fate of nutrients and chemicals used in upland
forests are examples of issues facing the forest products industry
today. Additionally, variation in technical specifications among the
Eastern states further complicates issues surrounding BMP prescription
effectiveness in riparian forests. As a result, additional research is
necessary to improve our understanding of the relationships between
forest management activities and water quality responses in aquatic and
semi-aquatic environments.

**DRAINMOD: A Field-Scale Model for Simulating Hydrology and Water
Quality for Shallow Water Table Soils**

M.A. Youssef^1^, R.W. Skaggs^1^, G.M. Chescheir^1^, C. Tian^1^, and D.M.
Amatya^2^

^1^Assistant Professor, WNR Distinguished Univ. Professor, Research
Assistant Professor, and Graduate Student, Biological and Agricultural
Engineering Department, North Carolina State University, Raleigh, NC
27695

^2^Research Hydrologist, Center for Forested Wetlands Research, USDA
Forest Service, Cordesville, SC 29434.

DRAINMOD (Skaggs, 1978) was originally developed for design and
evaluation of agricultural drainage and related water management
systems. DRAINMOD is a field-scale, one dimensional model that simulates
water and heat flow for high water table soils with artificial drainage
systems. It uses the water balance approach with functional
relationships to describe the main hydrologic processes and predict
subsurface drainage, surface runoff, infiltration, water table depth,
soil water content and evapotranspiration in response to given
climatological conditions, soil and crop properties, and drainage and
irrigation management. DRAINMOD simulates heat flow using finite
difference solution to the heat equation and predicts the temperature
distribution throughout the soil profile (Luo et al, 2000). The model
uses an empirical approach to predict the relative grain yield as
affected by planting date delays, soil water related stresses, and soil
salinity on crop yield (Evans et al., 1991; Seymour et al., 1992, Kandil
et al., 1995). The model has been extended to simulate the hydrology of
drained forests (McCarthy et al., 1992; Amatya et al., 1997). DRAINMOD
is well documented (e.g. Skaggs 1978, 1999) and several reports of model
validation and application (e.g. Skaggs et al. 1981; Skaggs 1982; Fouss
et al. 1987) have shown that DRAINMOD can reliably predict water table
fluctuations and drainage volumes.

DRAINMOD-N II (Youssef, 2003; Youssef et al. 2005), a major upgrade of
the original DRAINMOD-N model (Brevé et al., 1997), is a field-scale,
process-based model that simulates C and N dynamics in drained cropland
for a wide range of soil types, climatic conditions and farming
practices. As the name implies, DRAINMOD-N II is a companion model to
the widely used hydrologic model DRAINMOD. DRAINMOD-N II simulates
organic carbon dynamics using a C-cycle similar to that of the CENTURY
model (Parton et al., 1993). It simulates a detailed N cycle that
considers both mineral N (NO~3~-N, NH~4~-N, and NH~3~-N) and organic N
and their interaction as affected by C cycling. The model simulates
atmospheric deposition, plant uptake, N fixation by legumes, N
mineralization/immobilization, nitrification, denitrification, NH~3~
volatilization, and N losses via subsurface drainage and surface runoff.
It simulates farming practices such as tillage and plant residue
management and the application of mineral N fertilizers and animal
manure. It simulates nitrogen transport using numerical solution to a
multiphase form of the one dimensional advection-dispersion-reaction
equation. DRAINMOD-N II solves the ADR equation using a first-order,
explicit finite difference scheme (Youssef et al. 2005). Model
predictions include daily concentrations of mineral N (i.e. NO3 and NH4)
in soil solution and drain flow, organic C content of top 20 cm soil
layer, and rates of simulated N processes on daily, monthly, and annual
basis. DRAINMOD N II has been successfully tested using field data from
artificially drained soils with contrasting soil types, climatic
conditions, and farming practices (e.g. Youssef et al. 2006, Bechtold et
al., 2007).

Currently, a forestry version of DRAINMOD-N II is being developed by
adding a tree phenology and physiology component. This version of the
model will be capable of simulating tree growth and forest productivity
and water, C, and N dynamics in drained forests. The model will simulate
forest management practices such as fertilization, thinning, harvesting
and re-generation, and prescribed burning. The model will be tested
using data sets from two forested sites: Carteret 7 site, a managed pine
forest owned and operated by Weyerhaeuser Company at Carteret County in
eastern North Carolina, and WS 80 site, a naturally drained first order
watershed on a mixed hardwood and pine stand at USDA Forest Service,
Santee Experimental Forest in coastal South Carolina.

Comparative Features of Strengths, Weaknesses, Applications, and
Limitation of Five Hydrology and Water Quality Models for Nutrient
Cycling (Fate) and Transport Modeling

+---------------+---------+------+------------+------+-------+------+
| **Model       | **Eq    | **M  |            |      |       |      |
| Features and  | uations | odel |            |      |       |      |
| Char          | (P-B,   | Na   |            |      |       |      |
| acteristics** | E, S,   | me** |            |      |       |      |
|               | Q, or   |      |            |      |       |      |
|               | C)^1^** |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
|               |         | **DN | **         | **MI | **R   | **SW |
|               |         | DC** | DRAINMOD-N | KE-S | EMM** | AT** |
|               |         |      | II**       | HE** |       |      |
+---------------+---------+------+------------+------+-------+------+
| Developed     |         |      | Youssef et |      |       |      |
| by/at         |         |      | al, at     |      |       |      |
|               |         |      | NCSU-BAE   |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Field and/or  |         |      | Field      |      |       |      |
| Watershed     |         |      | scale      |      |       |      |
| scale         |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Forest Land   |         |      | No         |      |       |      |
| Use:          |         |      |            |      |       |      |
|               |         |      |            |      |       |      |
| Yes or No     |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| U             |         |      | Lowland    |      |       |      |
| pland/Lowland |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Largest area  |         |      | 480 km^2^  |      |       |      |
| applied,      |         |      |            |      |       |      |
| km^2^         |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Surface       |         |      | E          |      |       |      |
| Runoff/Flow   |         |      |            |      |       |      |
| generation    |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Subsurface    |         |      | P-B        |      |       |      |
| flow/Drainage |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Evapo         |         |      | Th         |      |       |      |
| transpiration |         |      | ornthwaite |      |       |      |
|               |         |      |            |      |       |      |
|               |         |      | or Direct  |      |       |      |
|               |         |      | input      |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Water Table   |         |      | P-B        |      |       |      |
| Dynamics      |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Nitrogen (N)  |         |      | P-B        |      |       |      |
| cycling       |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Phosphorus    |         |      | Not        |      |       |      |
| (P) cycling   |         |      | Included   |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Carbon (C)    |         |      | P-B        |      |       |      |
| cycling       |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| In-stream N   |         |      | Not        |      |       |      |
| transport     |         |      | Included   |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| In-stream P   |         |      | Not        |      |       |      |
| transport     |         |      | Included   |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| In-stream C   |         |      | Not        |      |       |      |
| transport     |         |      | Included   |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Riparian      |         |      | Not        |      |       |      |
| process for   |         |      | Included   |      |       |      |
| hydrology     |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Riparian      |         |      | Not        |      |       |      |
| process for   |         |      | Included   |      |       |      |
| nutrient      |         |      |            |      |       |      |
| cycling       |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Primary Input |         |      | Soil,      |      |       |      |
| Data          |         |      | Climate,   |      |       |      |
|               |         |      | Drain      |      |       |      |
|               |         |      | design,    |      |       |      |
|               |         |      | Crop and   |      |       |      |
|               |         |      | m          |      |       |      |
|               |         |      | anagement, |      |       |      |
|               |         |      | C and N    |      |       |      |
|               |         |      | tran       |      |       |      |
|               |         |      | sformation |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Temporal      |         |      | Hourly and |      |       |      |
| Scale         |         |      | less       |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Uncertainty   |         |      | No         |      |       |      |
| Analysis      |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Model         |         |      | NCSU-BAE   |      |       |      |
| Supported by  |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Possibility   |         |      | Y          |      |       |      |
| of Linkage;   |         |      |            |      |       |      |
| Y/N           |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Most recent   |         |      | The model  |      |       |      |
| published     |         |      | has not    |      |       |      |
| paper(s) for  |         |      | been       |      |       |      |
| forest        |         |      | applied to |      |       |      |
| eco-systems   |         |      | forestland |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Recent        |         |      | Developing |      |       |      |
| ongoing works |         |      | a forestry |      |       |      |
| including     |         |      | version of |      |       |      |
| extension     |         |      | DRAINMOD-N |      |       |      |
|               |         |      | II,        |      |       |      |
|               |         |      | Linking    |      |       |      |
|               |         |      | DRAINMOD-N |      |       |      |
|               |         |      | II to      |      |       |      |
|               |         |      | DRAI       |      |       |      |
|               |         |      | NMOD-based |      |       |      |
|               |         |      | watershed  |      |       |      |
|               |         |      | scale      |      |       |      |
|               |         |      | models.    |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Public Domain |         |      | Y          |      |       |      |
| (Y/N)         |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Other         |         |      |            |      |       |      |
| relevant info |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Model Contact |         |      | Mohamed    |      |       |      |
| person        |         |      | Youssef    |      |       |      |
+---------------+---------+------+------------+------+-------+------+

*^1^P-B = Process-based, E = Empirical, Q = Quasi-process-based, S=
Statistic*

**DRAINMOD Based Watershed-scale Models for Poorly Drained Watersheds**

G.M. Chescheir^1^, R.W. Skaggs^1^, M.A. Youssef^1^, G.P. Fernanadez^2^,
and D.M. Amatya^3^

^1^ Research Assistant Professor, WNR and Distinguished Univ. Professor,
and Assistant Professor, Biological and Agricultural Engineering
Department, North Carolina State University, Raleigh, NC 27695

^2^Senior Hydrologic Modeler, Applied Technology and Management, Inc.,
Gainesville,FL

^3^Research Hydrologist, Center for Forested Wetlands Research, USDA
Forest Service, Cordesville, SC 29434.

A suite of models has been developed for poorly drained watersheds. The
models use DRAINMOD to predict hydrology at the field scale and a range
of methods to predict channel hydraulics and nitrogen transport.
In-stream changes of N load are estimated with a lumped parameter
exponential decay function. The models have been tested using data from
a 10,000 ha eastern NC watershed. The models have been applied to four
other watersheds in eastern NC to predict nitrogen loads at the
watershed outlets and to predict the effect of land use changes on those
nitrogen loads. A brief description of the individual models is given
below.

### 

### Model 1, WATGIS (Fernandez et al., 2002) *is a GIS based, lumped parameter water quality model which uses spatially distributed delivery ratio (DR) parameters to account for nitrogen retention or loss along a drainage network. DR values are calculated from time of travel and an exponential decay model for in-stream processes. More complex models such as those below, or field observations can be used to develop relationships between travel time and daily flow depth, upstream drainage area and length of flow path from the field to the outlet. Once the relationships are developed WATGIS can be used to predict effects of land use and management practices on nutrient load at the outlet. Run times are fast, results can be displayed on GIS. Uncertainty analyses can be conducted within the model using Latin Hypercube Sampling (LHS) design.* 

*Model 2, DRAINMOD-GIS* (Fernandez et al., 2006) uses a simplified canal
routing model based on methods presented by Olivera and Maidment (1999).
Stream/canal routing is simulated with a kernal function based on the
first passage of time distribution to characterize the time of travel.
Nutrient transport is assumed to be by convection without dispersion
(slug flow) and in-stream losses of nitrogen are estimated with an
exponential decay function. The model performs uncertainty analyses
using LHS.

*Model 3*, *DRAINMOD-W*. (Fernandez et. al, 2005) This model combines
DRAINMOD with numerical solutions to the St.Venant equations for channel
hydraulics and solves the ADR equations for transport of chemicals. The
model uses a daily time step for updating channel water levels as a
boundary condition in DRAINMOD. The model is structured such that other
field scale models could be substituted for DRAINMOD so upland
watersheds could be considered. The model performs uncertainty analyses
using LHS.

*Model 4*, *DRAINMOD-DUFLOW* (Fernandez et al., 2003a) links DRAINMOD
for field predictions with DUFLOW (Aalderink et al., 1995) to describe
channel hydraulics and in-stream hydrodynamics. Flows from the field
outlet are routed on an hourly time step to the watershed outlet.
Routines in DUFLOW allow user specified models for predicting in-stream
changes in water quality. A lumped parameter exponential decay function
is used to predict loss of nitrogen as the water moves through the
canal/stream system.

*Model 5*, *DRAINWAT* (Amatya et al.,1997, 2003) This model combines
DRAINLOB (McCarthy et al., 1992) with FLD&STRM (Konyha and Skaggs, 1992)
which uses numerical solutions to the St.Venant equations for channel
hydraulics. DRAINLOB is a field scale model with modifications in
rainfall interception, subsurface drainage, and ET components of
DRAINMOD to more accurately describe hydrologic processes in pine
forests. Daily average stream velocities are used to calculate residence
times and in-stream losses or retention of nitrogen are estimated with
an exponential decay function built in a separate water quality module
outside of DRAINWAT. Dispersion during nutrient transport in the stream
is not considered.

Comparative Features of Strengths, Weaknesses, Applications, and
Limitation of Five Hydrology and Water Quality Models for Nutrient
Cycling (Fate) and Transport Modeling

+---------------+---------+------+------------+------+-------+------+
| **Model       | **Eq    | **M  |            |      |       |      |
| Features and  | uations | odel |            |      |       |      |
| Char          | (P-B,   | Na   |            |      |       |      |
| acteristics** | E, S,   | me** |            |      |       |      |
|               | Q, or   |      |            |      |       |      |
|               | C)^1^** |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
|               |         | **DN | **         | **MI | **R   | **SW |
|               |         | DC** | DRAINMOD-W | KE-S | EMM** | AT** |
|               |         |      | atershed** | HE** |       |      |
+---------------+---------+------+------------+------+-------+------+
| Developed     |         |      | NCSU-BAE   |      |       |      |
| by/at         |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Field and/or  |         |      | Field and  |      |       |      |
| Watershed     |         |      | Watershed  |      |       |      |
| scale         |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Forest Land   |         |      | Yes        |      |       |      |
| Use:          |         |      |            |      |       |      |
|               |         |      |            |      |       |      |
| Yes or No     |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| U             |         |      | Lowland    |      |       |      |
| pland/Lowland |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Largest area  |         |      | 15 km^2^   |      |       |      |
| applied,      |         |      |            |      |       |      |
| km^2^         |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Surface       |         |      | P-B        |      |       |      |
| Runoff/Flow   |         |      |            |      |       |      |
| generation    |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Subsurface    |         |      | P-B        |      |       |      |
| flow/Drainage |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Evapo         |         |      | Th         |      |       |      |
| transpiration |         |      | ornthwaite |      |       |      |
|               |         |      |            |      |       |      |
|               |         |      | or Direct  |      |       |      |
|               |         |      | input      |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Water Table   |         |      | P-B        |      |       |      |
| Dynamics      |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Nitrogen (N)  |         |      | E          |      |       |      |
| cycling       |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Phosphorus    |         |      | N          |      |       |      |
| (P) cycling   |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Carbon (C)    |         |      | N          |      |       |      |
| cycling       |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| In-stream N   |         |      | E          |      |       |      |
| transport     |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| In-stream P   |         |      | N          |      |       |      |
| transport     |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| In-stream C   |         |      | N          |      |       |      |
| transport     |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Riparian      |         |      | N          |      |       |      |
| process for   |         |      |            |      |       |      |
| hydrology     |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Riparian      |         |      | N          |      |       |      |
| process for   |         |      |            |      |       |      |
| nutrient      |         |      |            |      |       |      |
| cycling       |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Primary Input |         |      | Soil,      |      |       |      |
| Data          |         |      | Climate,   |      |       |      |
|               |         |      | Drain      |      |       |      |
|               |         |      | design,    |      |       |      |
|               |         |      | Crop       |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Temporal      |         |      | Hourly     |      |       |      |
| Scale         |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Uncertainty   |         |      | Yes        |      |       |      |
| Analysis      |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Model         |         |      | NCSU-BAE   |      |       |      |
| Supported by  |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Possibility   |         |      | Y          |      |       |      |
| of Linkage;   |         |      |            |      |       |      |
| Y/N           |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Most recent   |         |      | Fernandez  |      |       |      |
| published     |         |      | et al,     |      |       |      |
| paper(s) for  |         |      | (          |      |       |      |
| forest        |         |      | 2006,2007) |      |       |      |
| eco-systems   |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Recent        |         |      | Linking    |      |       |      |
| ongoing works |         |      | DRAINMOD N |      |       |      |
| including     |         |      |            |      |       |      |
| extension     |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Public Domain |         |      | Y          |      |       |      |
| (Y/N)         |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Other         |         |      |            |      |       |      |
| relevant info |         |      |            |      |       |      |
+---------------+---------+------+------------+------+-------+------+
| Model Contact |         |      | G.M.       |      |       |      |
| person        |         |      | Chescheir  |      |       |      |
+---------------+---------+------+------------+------+-------+------+

*^1^P-B = Process-based, E = Empirical, Q = Quasi-process-based, S=
Statistical, and C = Conceptual*

#### Application of APEX for Forestry

*Ali Saleh, Texas Institute for Applied Environmental Research, Tarleton
State University*

Forested watersheds are generally associated with higher water quality
than watersheds in other major land uses. However, the amount of
nutrients leaving a forested watershed may increase in response to
silvicultural practices such as timber harvesting and residue removal or
treatment. In response to this concern, all states with significant
commercial forests have developed BMPs to minimize water quality impacts
of forestry. Most individual forest products companies have voluntarily
adopted their own policies on company lands to protect water quality.

There are several benefits of modeling compared to watershed
experiments: modeling can represent the mean conditions of the simulated
area; it can explore the effects of a larger spectrum of possible
sequences of events; and it is not subject to environmental events, such
as meteorological extremes, that can affect to a great degree the
results of short-term watershed experiments.

The APEX model has components for routing water, sediment, nutrients,
and pesticides across complex landscapes and channel systems to the
watershed outlet. APEX also has groundwater and reservoir components. A
simulation area can be subdivided as much as necessary to assure that
each sub-area is relatively homogeneous in terms of soil, land use,
management, etc. The routing mechanisms provide for evaluation of
interactions between sub-areas involving surface runoff, return flow,
sediment deposition and degradation, nutrient transport, and groundwater
flow. The recent work has focused on adaptation of APEX to forest
conditions. To date, the predictive capabilities of APEX have been
validated using data from the Alto Watershed and, presently, using data
from the Dry Creek Watershed. Additional refinement and validation of
APEX, however, is needed to improve model capability to appreciate SMZ
contributions to water quality maintenance at the stand and watershed
scales. Furthermore, deciphering the beneficial role SMZs play in water
quality maintenance in mixed landuse watersheds also must be identified.

Scientists from the Texas Institute for Applied Environmental Research
in collaboration with researchers from the USDA-ARS Southeast Watershed
Research Laboratory in Tifton, GA propose to enhance our understanding
of nutrient storage and transformation processes in SMZs using modeling
techniques verified by in-house data maintained by ARS personnel.
Objectives of this study are twofold. First, to Evaluate the APEX
predictions of SMZ reductions in stream water sediment and nutrient
levels from mixed landuse watersheds in the Georgia Coastal Plain.
Second, utilize SWAPP ( Saleh and Gallego, 2007) to evaluate forested
SMZ influences on water quality within a mixed landuse watershed.
Environmental models are used to assess and evaluate various best
management practices (BMPs) at field (e.g., APEX) and watershed (e.g.,
Soil and Water Assessment Tool, SWAT) levels. However, models such as
SWAT and APEX are only capable of simulating, mechanistically, a limited
number of BMP scenarios individually. Therefore, the automated program,
SWAPP, was developed to convert SWAT files to-and-from APEX format and
simulate SWAT and APEX simultaneously.

The results and status of the above studies will be presented.

**Comparative Features of Strengths, Weaknesses, Applications, and
Limitation of Five Hydrology and Water Quality Models for Nutrient
Cycling (Fate) and Transport Modeling**

+-------------+-------+----------+----------+----------+------+-----+
| **Model     | *     | **Model  |          |          |      |     |
| Features    | *Equa | Name**   |          |          |      |     |
| and         | tions |          |          |          |      |     |
| Charac      | (P-B, |          |          |          |      |     |
| teristics** | E, S, |          |          |          |      |     |
|             | Q, or |          |          |          |      |     |
|             | C)    |          |          |          |      |     |
|             | ^1^** |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
|             |       | **APEX** | **SWAT** | **CEEOT  | **RE | **  |
|             |       |          |          | -SWAPP** | MM** | SWA |
|             |       |          |          |          |      | T** |
+-------------+-------+----------+----------+----------+------+-----+
| Developed   | P-S   | USDA-ARS | USDA-ARS | TIAER    |      |     |
| by/at       |       | Temple,  |          |          |      |     |
|             |       | TEXAS    | Temple,  | Steph    |      |     |
|             |       |          |          | enville, |      |     |
|             |       |          | TEXAS    | Texas    |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Field       |       | FIELD    | W        | BOTH     |      |     |
| and/or      |       |          | ATERSHED |          |      |     |
| Watershed   |       |          |          |          |      |     |
| scale       |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Forest Land |       | YES      | YES      | YES      |      |     |
| Use:        |       |          |          |          |      |     |
|             |       |          |          |          |      |     |
| Yes or No   |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Upl         |       | YES      | YES      | YES      |      |     |
| and/Lowland |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Largest     |       | U        | LIMITED  | U        |      |     |
| area        |       | NLIMITED |          | NLIMITED |      |     |
| applied,    |       |          |          |          |      |     |
| km^2^       |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Surface     |       | YES      | YES      | YES      |      |     |
| Runoff/Flow |       |          |          |          |      |     |
| generation  |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Subsurface  |       | YES      | YES      | YES      |      |     |
| fl          |       |          |          |          |      |     |
| ow/Drainage |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Evapotr     |       | 5        | 5        | 5        |      |     |
| anspiration |       | OPTIONS  | OPTIONS  | OPTIONS  |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Water Table |       | YES      | YES      | YES      |      |     |
| Dynamics    |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Nitrogen    |       | YES      | YES      | YES      |      |     |
| (N) cycling |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Phosphorus  |       | YES      | YES      | YES      |      |     |
| (P) cycling |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Carbon (C)  |       | NOT      | YES      | YES      |      |     |
| cycling     |       | C        |          |          |      |     |
|             |       | URRENTLY |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| In-stream N |       | YES      | NO       | YES      |      |     |
| transport   |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| In-stream P |       | YES      | NO       | YES      |      |     |
| transport   |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| In-stream C |       | NO       | NO       | NO       |      |     |
| transport   |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Riparian    |       | POSSIBLE | YES      | YES      |      |     |
| process for |       |          |          |          |      |     |
| hydrology   |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Riparian    |       | POSSIBLE | YES      | YES      |      |     |
| process for |       |          |          |          |      |     |
| nutrient    |       |          |          |          |      |     |
| cycling     |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Primary     |       |          |          |          |      |     |
| Input Data  |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Temporal    |       | DAIL     | DAIL     | DAIL     |      |     |
| Scale       |       | Y-MONTHL | Y-MONTHL | Y-MONTHL |      |     |
|             |       | Y-ANNUAL | Y-ANNUAL | Y-ANNUAL |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Uncertainty |       | YES      | NO       | YES      |      |     |
| Analysis    |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Model       |       | USDA-ARS | USDA-ARS | TIAER    |      |     |
| Supported   |       |          |          |          |      |     |
| by          |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Possibility |       | YES      | YES      | YES      |      |     |
| of Linkage; |       |          |          |          |      |     |
| Y/N         |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Most recent |       | A        | A        | A        |      |     |
| published   |       | VAILABLE | VAILABLE | VAILABLE |      |     |
| paper(s)    |       |          |          |          |      |     |
| for forest  |       |          |          |          |      |     |
| eco-systems |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Recent      |       |          |          |          |      |     |
| ongoing     |       |          |          |          |      |     |
| works       |       |          |          |          |      |     |
| including   |       |          |          |          |      |     |
| extension   |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Public      |       | YES      | YES      | YES      |      |     |
| Domain      |       |          |          |          |      |     |
| (Y/N)       |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Other       |       |          |          |          |      |     |
| relevant    |       |          |          |          |      |     |
| info        |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+
| Model       |       | Jeff     | Jimmy    | Ali      |      |     |
| Contact     |       | Arnold   | Williams | Saleh    |      |     |
| person      |       |          |          |          |      |     |
+-------------+-------+----------+----------+----------+------+-----+

*^1^P-B = Process-based, E = Empirical, Q = Quasi-process-based, S=
Statistical, and C = Conceptual*

# SWAT Abstract: Cole Green Rossi and Jeff Arnold

The SWAT model is a compilation of USDA ARS efforts to model
environmental processes in agricultural systems. Components of the
CREAMS (daily rainfall hydrology), GLEAMS (pesticide) and EPIC (crop
growth) models are incorporated into SWAT. The current SWAT model is a
direct descendant of the Simulator for Water Resources in Rural Basins
(SWRRB) model which simulates management impacts on water and sediment
movement for ungauged rural basins across the U.S. The SWAT model has
been evolving since the early 1990s in Temple, Texas. Its development,
modifications, and support continue to be made in Temple with assistance
from domestic and international contributors and users. The code is
public domain and is monitored using version control software. This
watershed-scale model has simulated areas from 0.006 km^2^ (Riesel,
Texas) to 795,000 km^2^ (Mekong River Basin).

Basic input data required by the model are: soils, temperature,
precipitation, runoff, land use, and watershed delineation. Climatic
inputs are: daily precipitation, maximum and minimum temperature, solar
radiation data, relative humidity, and wind speed data.
Evapotranspiration methods include: Penman-Montieth (P-B),
Priestly-Taylor (Q), and Hargreaves (E). The hydrologic balance
simulated in SWAT is simulated per hydrologic response unit (HRU: unique
combination of land use, soil, and management characteristics); canopy
interception; partitioning of precipitation, snowmelt water and
irrigation water between surface runoff (Green-Ampt (P-B) and Curve
Number (E) methods) and infiltration, redistribution of water within the
soil profile, evapotranspiration, lateral subsurface (kinematic storage)
flow from the soil profile, and return flow from shallow aquifers.
Groundwater is simulated via exponential baseflow recession. SWAT can
generate sub-hourly runoff; all other constituents are reported on a
daily timestep. Flows are summed from all HRUs to the subwatershed
level, and then routed through the stream system using a variable-rate
storage method or the Muskingum method. Additional routines include in
SWAT that impact hydrology include a soil cracking and tile drain
routines. Hooghoudt's and Kirkham tile equations are being adapted from
DRAINMOD as an option in SWAT by Dr. Moriasi (ARS, OK). A current
work-in-progress is the development of a landscape position routing
scheme to the HRUs (Volk, Allen, Arnold). Usage of this landscape
version will enhance SWAT's spatial detail capability as a water quality
and land management decision-making tool.

SWAT can estimate HRU-level and in-stream sediment, nitrogen (N),
phosphorus (P), bacteria and pesticide losses. These concentrations or
loadings are summed at the subwatershed level and the losses are routed
through channels, ponds, wetlands, depressional areas, and/or reservoirs
to the watershed outlet. SWAT has the option to select the routing of
in-stream nutrient loadings with (QUAL2E) or without transformations.
Both N and P have inorganic and organic pools which are impacted by the
amount of organic carbon (C) present in the soil. SWAT currently assumes
that soil carbon contents are static. Sediment transport is simulated as
a function of peak channel velocity. Carbon fractionation and the impact
of tillage operations and root decomposition are currently being adapted
from the CFARM model. Phosphorus can now move throughout the soil
profile and through subsurface drains.

In order to simulate vegetative buffer strips, SWAT uses a loss rate and
does not yet include process modeling. Wetlands can be simulated on the
basis of one wetland per subwatershed, which is assumed to capture
discharge and pollutant loads from a user-specified percentage of the
overall subwatershed. SWAT can simulate forest land use however, species
are not competitively grown. SWAT does not have a biomass burn equation
but a burn can be scheduled based on change in CN (no processes
simulated).

SWAT2005 includes automated sensitivity, calibration, and uncertainty
analysis components. SWAT has multiple interfaces including AV-SWATX,
ArcSWAT and VizSWAT, and MapWindows. SWAT has been linked with APEX,
REMM, MODFLOW, WEPP, DNDC (for N), and 3-PG (plant growth).

Gassman, P.W., M. R. Reyes, C.H. Green, and J.G. Arnold. 2007. The Soil
and Water Assessment Tool: Historical Development, Applications, and
Future Research Directions. 50(4):1211-1250

**Comparative Features of Strengths, Weaknesses, Applications, and
Limitation of Five Hydrology and Water Quality Models for Nutrient
Cycling (Fate) and Transport Modeling**

+-------------+-------+-----+----------+-----+------+----------------+
| **Model     | *     | *   |          |     |      |                |
| Features    | *Equa | *Mo |          |     |      |                |
| and         | tions | del |          |     |      |                |
| Charac      | (P-B, | Nam |          |     |      |                |
| teristics** | E, S, | e** |          |     |      |                |
|             | Q, or |     |          |     |      |                |
|             | C)    |     |          |     |      |                |
|             | ^1^** |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
|             |       | **  | **DRAINM | **M | **RE | **SWAT**       |
|             |       | DND | OD-NII** | IKE | MM** |                |
|             |       | C** |          | -SH |      |                |
|             |       |     |          | E** |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Developed   |       |     |          |     |      | Temple; Arnold |
| by/at       |       |     |          |     |      | & Williams     |
+-------------+-------+-----+----------+-----+------+----------------+
| Watershed   |       |     |          |     |      | Watershed      |
| scale       |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Forest Land |       |     |          |     |      | Yes and no     |
| Use:        |       |     |          |     |      |                |
|             |       |     |          |     |      |                |
| Yes or No   |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Upl         |       |     |          |     |      | In progress    |
| and/Lowland |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Largest     |       |     |          |     |      | 795000         |
| area        |       |     |          |     |      |                |
| applied,    |       |     |          |     |      |                |
| km^2^       |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Surface     | E and |     |          |     |      | CN, Green-Ampt |
| Runoff/Flow | P-B   |     |          |     |      |                |
| generation  |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Subsurface  | E     |     |          |     |      | Kinematic      |
| fl          |       |     |          |     |      | st             |
| ow/Drainage |       |     |          |     |      | orage-lateral; |
|             |       |     |          |     |      | GW-exp. BF     |
|             |       |     |          |     |      | recession      |
+-------------+-------+-----+----------+-----+------+----------------+
| Evapotr     | E,    |     |          |     |      | P-M, P-T,      |
| anspiration | P-B,  |     |          |     |      | Hargreaves     |
|             | Q     |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Water Table | P-B   |     |          |     |      | Tile drains    |
| Dynamics    |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Nitrogen    | E     |     |          |     |      |                |
| (N) cycling |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Phosphorus  | E     |     |          |     |      |                |
| (P) cycling |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Carbon (C)  | E & Q |     |          |     |      | Static/CFARM   |
| cycling     |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| In-stream N | E     |     |          |     |      | QUAL2          |
| transport   |       |     |          |     |      | E/Conservative |
+-------------+-------+-----+----------+-----+------+----------------+
| In-stream P | E     |     |          |     |      | QUAL2          |
| transport   |       |     |          |     |      | E/Conservative |
+-------------+-------+-----+----------+-----+------+----------------+
| In-stream C | None  |     |          |     |      |                |
| transport   |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Riparian    | E     |     |          |     |      | Quasi-buffers  |
| process for |       |     |          |     |      |                |
| hydrology   |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Riparian    | P-B   |     |          |     |      | Plant uptake   |
| process for |       |     |          |     |      |                |
| nutrient    |       |     |          |     |      |                |
| cycling     |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Primary     | P-B/E |     |          |     |      | Weather,       |
| Input Data  |       |     |          |     |      | soils, land    |
|             |       |     |          |     |      | use, runoff,   |
|             |       |     |          |     |      | watershed      |
|             |       |     |          |     |      | delineation    |
+-------------+-------+-----+----------+-----+------+----------------+
| Temporal    |       |     |          |     |      | Daily          |
| Scale       |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Uncertainty |       |     |          |     |      | yes            |
| Analysis    |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Model       |       |     |          |     |      | Temple, TX ARS |
| Supported   |       |     |          |     |      |                |
| by          |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Possibility |       |     |          |     |      | Y              |
| of Linkage; |       |     |          |     |      |                |
| Y/N         |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Most recent |       |     |          |     |      | See Gassman et |
| published   |       |     |          |     |      | al. (2007)     |
| paper(s)    |       |     |          |     |      | citation       |
| for forest  |       |     |          |     |      |                |
| eco-systems |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Recent      |       |     |          |     |      | C, landscape   |
| ongoing     |       |     |          |     |      | position, P,   |
| works       |       |     |          |     |      | pesticides,    |
| including   |       |     |          |     |      | Almanac        |
| extension   |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Public      |       |     |          |     |      | Yes            |
| Domain      |       |     |          |     |      |                |
| (Y/N)       |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Other       |       |     |          |     |      |                |
| relevant    |       |     |          |     |      |                |
| info        |       |     |          |     |      |                |
+-------------+-------+-----+----------+-----+------+----------------+
| Model       |       |     |          |     |      | Jeff           |
| Contact     |       |     |          |     |      | Arnold/Cole    |
| person      |       |     |          |     |      | Rossi/Nancy    |
|             |       |     |          |     |      | Sammons        |
+-------------+-------+-----+----------+-----+------+----------------+

*^1^P-B = Process-based, E = Empirical, Q = Quasi-process-based, S=
Statistical, and C = Conceptual*

Applications of the **MIKE SHE** model in Forested Watersheds in the
Southeastern United States

Ge Sun^1^, Jianbiao Lu^1^, Zhaohua Dai,^2^ Devendra Amayta^3^, and Jim
Vose^4^

1\. Southern Global Change Program,

Southern Research Station, US Forest Service. Email: Ge_Sun@ncsu.edu

2\. University of New Hampshire

3\. Center for Forested Wetlands Research

USDA Forest Service

4\. Coweeta Hydrologic Lab, USDA Forest Service

Hydrologic pathways and processes vary greatly from the coastal plains
to the mountainous uplands across the southeastern U.S. due to the large
physiographic and climatic gradients. We hypothesized that different
regions have different hydrologic responses to forest management and
climate change due to different conditions - topography, climate, soil
and vegetations. The objectives of this study were: 1). To evaluate the
applicability of a physically-based, distributed modeling system - MIKE
SHE/MIKE 11 in the southeastern U.S.; and 2). To use the MIKE SHE/MIKE
11 modeling system to examine the hydrologic processes and study the
responses to forest management practices and climate change on the
coastal plain and the mountainous upland in the southeastern U.S. Four
experimental watersheds with three in wetlands on the coastal plain
(Florida pine flatwoods, Santee WS#80, NC drained Loblolly pine
plantations) and one at the Appalachian mountainous upland (Coweeta
WS#2) were selected. The model was first evaluated to determine if it
can sufficiently describe the hydrological processes in these diverse
watersheds in these two contrasting regions. Then, the model was applied
to simulate the hydrologic impacts of forest management and climate
change at these four study sites. Four simulation scenarios were
performed at each site. These included the base line, clearcut, 2 C
temperature increase and 10% precipitation decrease scenarios. The water
table level and streamflow amount were used as two responses to evaluate
the forest management and climate change impacts.

This study indicated that forest management and climate change would
have potential impacts on the wetland water table, especially during dry
periods. The absolute magnitudes of streamflow reduction were larger in
a wet year than in a dry year for the two watersheds under two climate
change scenarios of 2 C temperature increase and 10% precipitation
decrease. In terms of streamflow reduction percentages, the results
seemed to suggest that climate change would have higher impacts on the
coastal plain than the mountainous upland. However, more field data and
research are needed to further test this hypothesis.

This study also showed that MIKE SHE is well suited for describing
hydrologic processes in the humid southeastern forest ecosystems at a
watershed scale. It is easy to apply to ungaged watersheds when GIS data
are available, and most parameters can be derived from published
literature. MIKE SHE over-predicted soil evaporation from disturbed
harvested lands. Thus, the model might have underestimated the
streamflow impacts due to clearcut. Also, a process-based
evapotranspiration model is needed to fully describe the evaporation
processes under the harvested conditions. Parameterization of
distributed models remains challenging. Internal model validation of the
hydrologic processes is needed.

**Comparative Features of Strengths, Weaknesses, Applications, and
Limitation of Five Hydrology and Water Quality Models for Nutrient
Cycling (Fate) and Transport Modeling**

+--------------+--------+------+-----------+----------+------+------+
| **Model      | **Equ  | **M  |           |          |      |      |
| Features and | ations | odel |           |          |      |      |
| Chara        | (P-B,  | Na   |           |          |      |      |
| cteristics** | E, S,  | me** |           |          |      |      |
|              | Q, or  |      |           |          |      |      |
|              | C      |      |           |          |      |      |
|              | )^1^** |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
|              |        | **DN | **DRAIN   | **MI     | **RE | **SW |
|              |        | DC** | MOD-NII** | KE-SHE** | MM** | AT** |
+--------------+--------+------+-----------+----------+------+------+
| Developed    |        |      |           | DHI, Inc |      |      |
| by/at        |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Field and/or |        |      |           | W        |      |      |
| Watershed    |        |      |           | atershed |      |      |
| scale        |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Forest Land  |        |      |           | YES      |      |      |
| Use:         |        |      |           |          |      |      |
|              |        |      |           |          |      |      |
| Yes or No    |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Up           |        |      |           | both     |      |      |
| land/Lowland |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Largest area |        |      |           | 10\^3    |      |      |
| applied,     |        |      |           |          |      |      |
| km^2^        |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Surface      | P-B    |      |           | both     |      |      |
| Runoff/Flow  |        |      |           |          |      |      |
| generation   |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Subsurface   | P-B    |      |           | yes      |      |      |
| f            |        |      |           |          |      |      |
| low/Drainage |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Evapot       | F      |      |           | Yes      |      |      |
| ranspiration | AO-P-T |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Water Table  | P-B    |      |           | Yes      |      |      |
| Dynamics     |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Nitrogen (N) | n      |      |           | n        |      |      |
| cycling      |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Phosphorus   | n      |      |           | n        |      |      |
| (P) cycling  |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Carbon (C)   | n      |      |           | n        |      |      |
| cycling      |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| In-stream N  | n      |      |           | n        |      |      |
| transport    |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| In-stream P  | n      |      |           | n        |      |      |
| transport    |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| In-stream C  | n      |      |           | n        |      |      |
| transport    |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Riparian     | P-B    |      |           | n        |      |      |
| process for  |        |      |           |          |      |      |
| hydrology    |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Riparian     | N      |      |           | n        |      |      |
| process for  |        |      |           |          |      |      |
| nutrient     |        |      |           |          |      |      |
| cycling      |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Primary      | P-B    |      |           | Climate, |      |      |
| Input Data   |        |      |           | soil,    |      |      |
|              |        |      |           | LAI, DEM |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Temporal     |        |      |           | n        |      |      |
| Scale        |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Uncertainty  |        |      |           | n        |      |      |
| Analysis     |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Model        |        |      |           | n        |      |      |
| Supported by |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Possibility  |        |      |           | Y        |      |      |
| of Linkage;  |        |      |           |          |      |      |
| Y/N          |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Most recent  |        |      |           | Lu, J.B. |      |      |
| published    |        |      |           | Diss     |      |      |
| paper(s) for |        |      |           | ertation |      |      |
| forest       |        |      |           |          |      |      |
| eco-systems  |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Recent       |        |      |           | Appl     |      |      |
| ongoing      |        |      |           | ications |      |      |
| works        |        |      |           | in China |      |      |
| including    |        |      |           | s        |      |      |
| extension    |        |      |           | emi-arid |      |      |
|              |        |      |           | regions  |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Public       |        |      |           | N        |      |      |
| Domain (Y/N) |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Other        |        |      |           | Co       |      |      |
| relevant     |        |      |           | mmercial |      |      |
| info         |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+
| Model        |        |      |           |          |      |      |
| Contact      |        |      |           |          |      |      |
| person       |        |      |           |          |      |      |
+--------------+--------+------+-----------+----------+------+------+

*^1^P-B = Process-based, E = Empirical, Q = Quasi-process-based, S=
Statistical, and C = Conceptual*

**Forest-DNDC -- A process-based biogeochemical model**

Changsheng Li ^1^, Carl Trettin ^2^ and Zhaohua Dai ^1,3^

1.  CSRC, EOS, University of New Hampshire, 39 College Rd. Durham, NH
    03824

2.  Center for Forested Wetlands Research, SRS, USDA, 3734 Highway 402,
    Cordesville, SC 29434

3.  Working address: Center for Forested Wetlands Research, SRS, USDA,
    3734 Highway 402, Cordesville, SC 29434

Forest-DNDC (DNDC stands for DeNitrification-DeComposition) is a
process-based computer simulation model of carbon and nitrogen
biogeochemistry in soil-plant ecosystems. It can be used for predicting
tree growth, soil temperature and moisture regimes, soil carbon
dynamics, nitrogen leaching, and emissions of trace gases including
nitrous oxide (N2O), nitric oxide (NO), dinitrogen (N2), ammonia (NH3),
methane (CH4) and carbon dioxide (CO2). 

The current version is a field scale for both pine and hardwoods,
especially for popular species. The applied size depends on the
geography and topography. C and N cycling is mainly concentrated on C
and N balance in soil and vegetation, as well as greenhouse gas
production and emission. Soil N balance is\
SN = litterN + fertilizerN + PrecipitationN -- plantUptakeN - leachingN
-- gasN

Soil C balance is

SOC = litterC + fertilizerC -- leachingC - soilRespC

Its temporal size is daily for both input and output. The main input
data include soil properties, vegetation info (depends on the study
objectives), climate, hydrology (depends on the study objectives),
geographic coordinates, land use and land management.

In Forest-DNDC, surface and subsurface flows are not simulated; only
one-dimensional water movement is simulated, including ET. Soil water
content is

SW = P -- ET -- to-aquifer -- other

In DNDC, soil water content only depends on soil hydraulic properties to
determine how much water can be kept in soil during raining, any extra
water (approximate to runoff) will be removed from the model; and then
how much water loss to ET and aquifer will be calculated. Lateral flow
is not considered. Therefore, it only works well for uplands. For
lowlands it needs a good hydrologic model to be linked although an
empirical hydrologic functionality has been developed for lowlands.
Currently MIKE SHE is being linked to Forest-DNDC for lowlands.

Forest-DNDC is an academic software, but commercial, like DRAINMOD. It
can be free for any users, and possible to be linked. In fact, some
model developers have let DNDC developer know that some codes have been
used in their models.

Recent published papers:

> Leip et al., 2007. Linking an economic model for European agriculture
> with a mechanistic model to estimate nitrogen and carbon losses from
> arable soils in Europe, Biogeosciences, 5, 73-94, 2008
>
> Beheydt et al., 2007. Validation of DNDC for 22 long-term N2O field
> emission measurements. Atmospheric Environment 41:6196-6211
>
> Li, 2007. Quantifying greenhouse gas emissions from soils: Scientific
> basis and modeling approach. Soil Science and Plant Nutrition
> 53:344-352
>
> Tonitto et al., 2007, Application of the DNDC model to tile-drained
> Illinois agroecosystems: model calibration, validation, and
> uncertainty analysis, Nutrient Cycling in Agroecosystems DOI
> 10.1007/s10705-006-9076-0

**Comparative Features of Strengths, Weaknesses, Applications, and
Limitation of Five Hydrology and Water Quality Models for Nutrient
Cycling (Fate) and Transport Modeling**

+--------------+--------+----------+-----------+------+------+------+
| **Model      | **Equ  | **Model  |           |      |      |      |
| Features and | ations | Name**   |           |      |      |      |
| Chara        | (P-B,  |          |           |      |      |      |
| cteristics** | E, S,  |          |           |      |      |      |
|              | Q, or  |          |           |      |      |      |
|              | C      |          |           |      |      |      |
|              | )^1^** |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
|              |        | **DNDC** | **DRAIN   | **MI | **RE | **SW |
|              |        |          | MOD-NII** | KE-S | MM** | AT** |
|              |        |          |           | HE** |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Developed    |        | UNH      |           |      |      |      |
| by/at        |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Field and/or |        | Field    |           |      |      |      |
| Watershed    |        |          |           |      |      |      |
| scale        |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Forest Land  |        | Yes      |           |      |      |      |
| Use:         |        |          |           |      |      |      |
|              |        |          |           |      |      |      |
| Yes or No    |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Up           |        | Upland   |           |      |      |      |
| land/Lowland |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Largest area |        | Depend   |           |      |      |      |
| applied,     |        | on       |           |      |      |      |
| km^2^        |        | to       |           |      |      |      |
|              |        | pography |           |      |      |      |
|              |        | &        |           |      |      |      |
|              |        | g        |           |      |      |      |
|              |        | eography |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Surface      |        | C        |           |      |      |      |
| Runoff/Flow  |        |          |           |      |      |      |
| generation   |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Subsurface   |        | C        |           |      |      |      |
| f            |        |          |           |      |      |      |
| low/Drainage |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Evapot       |        | Thor     |           |      |      |      |
| ranspiration |        | nthwaite |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Water Table  |        | N        |           |      |      |      |
| Dynamics     |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Nitrogen (N) |        | P-B      |           |      |      |      |
| cycling      |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Phosphorus   |        | P-B      |           |      |      |      |
| (P) cycling  |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Carbon (C)   |        | P-B      |           |      |      |      |
| cycling      |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| In-stream N  |        | N        |           |      |      |      |
| transport    |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| In-stream P  |        | N        |           |      |      |      |
| transport    |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| In-stream C  |        | N        |           |      |      |      |
| transport    |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Riparian     |        | N        |           |      |      |      |
| process for  |        |          |           |      |      |      |
| hydrology    |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Riparian     |        | N        |           |      |      |      |
| process for  |        |          |           |      |      |      |
| nutrient     |        |          |           |      |      |      |
| cycling      |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Primary      |        | Climate, |           |      |      |      |
| Input Data   |        | soil,    |           |      |      |      |
|              |        | plant    |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Temporal     |        |          |           |      |      |      |
| Scale        |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Uncertainty  |        |          |           |      |      |      |
| Analysis     |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Model        |        |          |           |      |      |      |
| Supported by |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Possibility  |        | Y        |           |      |      |      |
| of Linkage;  |        |          |           |      |      |      |
| Y/N          |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Most recent  |        | Li et    |           |      |      |      |
| published    |        | al.      |           |      |      |      |
| paper(s) for |        |          |           |      |      |      |
| forest       |        |          |           |      |      |      |
| eco-systems  |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Recent       |        | Linking  |           |      |      |      |
| ongoing      |        | MIKE SHE |           |      |      |      |
| works        |        |          |           |      |      |      |
| including    |        |          |           |      |      |      |
| extension    |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Public       |        | Y        |           |      |      |      |
| Domain (Y/N) |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Other        |        |          |           |      |      |      |
| relevant     |        |          |           |      |      |      |
| info         |        |          |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+
| Model        |        | Ch       |           |      |      |      |
| Contact      |        | angsheng |           |      |      |      |
| person       |        | Li       |           |      |      |      |
+--------------+--------+----------+-----------+------+------+------+

*^1^P-B = Process-based, E = Empirical, Q = Quasi-process-based, S=
Statistical, and C = Conceptual*

**REMM: Riparian Ecosystem Management Model**

Lowrance, R., Williams, R., and Bosch, D.

USDA-ARS, Southeast Watershed Research Laboratory, Tifton, Georgia

In many landscapes, riparian buffer zones can be effective conservation
practices for mitigating nonpoint source pollution. Their potential use
as a best management practice has been limited because of the lack of a
design procedure that can quantify their effectiveness for different
climatic, soil, and vegetation conditions. The Riparian Ecosystem
Management Model (REMM) was developed for researchers and natural
resource agencies as a modeling tool that can help to quantify the water
quality benefits of riparian buffers under varying site conditions.
Processes simulated in REMM include surface and subsurface hydrology;
erosion, sediment transport, and deposition; carbon, nitrogen, and
phosphorous transport, removal, and cycling; and vegetation growth. The
model operates on a daily time step. Management options such as
vegetation type, buffer configuration, and biomass harvesting can be
simulated. Recent work with the REMM model has focused upon parameter
sensitivity and application for optimizing buffer sizes based upon
potential nutrient loading. REMM can be used in conjunction with upland
models, empirical data, or estimated loadings to examine buffer design
for hillslope transport. Efforts are underway to link REMM with the
upland components of the SWAT and the AnnAGNPS models.

**Comparative Features of Strengths, Weaknesses, Applications, and
Limitation of Five Hydrology and Water Quality Models for Nutrient
Cycling (Fate) and Transport Modeling**

+------------+-------+----+------+----+---------------+--------------+
| **Model    | *     | *  |      |    |               |              |
| Features   | *Equa | *M |      |    |               |              |
| and        | tions | od |      |    |               |              |
| Charact    | (P-B, | el |      |    |               |              |
| eristics** | E, S, | Na |      |    |               |              |
|            | Q, or | me |      |    |               |              |
|            | C)    | ** |      |    |               |              |
|            | ^1^** |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
|            |       | ** | **DR | ** | **REMM**      | **SWAT**     |
|            |       | DN | AINM | MI |               |              |
|            |       | DC | OD-N | KE |               |              |
|            |       | ** | II** | -S |               |              |
|            |       |    |      | HE |               |              |
|            |       |    |      | ** |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Developed  |       |    |      |    | USDA-ARS,     |              |
| by/at      |       |    |      |    | SEWRL Tifton, |              |
|            |       |    |      |    | GA            |              |
+------------+-------+----+------+----+---------------+--------------+
| Field      |       |    |      |    | Field         |              |
| and/or     |       |    |      |    |               |              |
| Watershed  |       |    |      |    |               |              |
| scale      |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Forest     |       |    |      |    | Yes           |              |
| Land Use:  |       |    |      |    |               |              |
|            |       |    |      |    |               |              |
| Yes or No  |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Upla       |       |    |      |    | Lowland       |              |
| nd/Lowland |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Largest    |       |    |      |    | 0.1           |              |
| area       |       |    |      |    |               |              |
| applied,   |       |    |      |    |               |              |
| km^2^      |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Surface    |       |    |      |    | P-B, modified |              |
| R          |       |    |      |    | Green-Ampt    |              |
| unoff/Flow |       |    |      |    |               |              |
| generation |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Subsurface |       |    |      |    | P-B, mass     |              |
| flo        |       |    |      |    | balance based |              |
| w/Drainage |       |    |      |    | on field      |              |
|            |       |    |      |    | capacity      |              |
+------------+-------+----+------+----+---------------+--------------+
| Evapotra   |       |    |      |    | P-B, modified |              |
| nspiration |       |    |      |    | Pe            |              |
|            |       |    |      |    | nman-Monteith |              |
+------------+-------+----+------+----+---------------+--------------+
| Water      |       |    |      |    | P-B, Darcy\'s |              |
| Table      |       |    |      |    | equation      |              |
| Dynamics   |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Nitrogen   |       |    |      |    | P-B           |              |
| (N)        |       |    |      |    |               |              |
| cycling    |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Phosphorus |       |    |      |    | P-B           |              |
| (P)        |       |    |      |    |               |              |
| cycling    |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Carbon (C) |       |    |      |    | P-B           |              |
| cycling    |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| In-stream  |       |    |      |    | None,         |              |
| N          |       |    |      |    | simulation    |              |
| transport  |       |    |      |    | ends with     |              |
|            |       |    |      |    | delivery to   |              |
|            |       |    |      |    | the stream    |              |
+------------+-------+----+------+----+---------------+--------------+
| In-stream  |       |    |      |    | none,         |              |
| P          |       |    |      |    | simulation    |              |
| transport  |       |    |      |    | ends with     |              |
|            |       |    |      |    | delivery to   |              |
|            |       |    |      |    | the stream    |              |
+------------+-------+----+------+----+---------------+--------------+
| In-stream  |       |    |      |    | none,         |              |
| C          |       |    |      |    | simulation    |              |
| transport  |       |    |      |    | ends with     |              |
|            |       |    |      |    | delivery to   |              |
|            |       |    |      |    | the stream    |              |
+------------+-------+----+------+----+---------------+--------------+
| Riparian   |       |    |      |    | P-B, same as  |              |
| process    |       |    |      |    | upland        |              |
| for        |       |    |      |    |               |              |
| hydrology  |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Riparian   |       |    |      |    | P-B, same as  |              |
| process    |       |    |      |    | upland        |              |
| for        |       |    |      |    |               |              |
| nutrient   |       |    |      |    |               |              |
| cycling    |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Primary    |       |    |      |    | Climate,      |              |
| Input Data |       |    |      |    | soils,        |              |
|            |       |    |      |    | vegetation,   |              |
|            |       |    |      |    | management    |              |
+------------+-------+----+------+----+---------------+--------------+
| Temporal   |       |    |      |    | Daily         |              |
| Scale      |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| U          |       |    |      |    | Inamdar et al |              |
| ncertainty |       |    |      |    | 1999a, 1999b  |              |
| Analysis   |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Model      |       |    |      |    | USDA-ARS,     |              |
| Supported  |       |    |      |    | SEWRL,        |              |
| by         |       |    |      |    | Tifton, GA    |              |
+------------+-------+----+------+----+---------------+--------------+
| P          |       |    |      |    | Y             |              |
| ossibility |       |    |      |    |               |              |
| of         |       |    |      |    |               |              |
| Linkage;   |       |    |      |    |               |              |
| Y/N        |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Most       |       |    |      |    | Bhat et al.   |              |
| recent     |       |    |      |    | 2007          |              |
| published  |       |    |      |    |               |              |
| paper(s)   |       |    |      |    |               |              |
| for forest |       |    |      |    |               |              |
| e          |       |    |      |    |               |              |
| co-systems |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Recent     |       |    |      |    | Linkage to    |              |
| ongoing    |       |    |      |    | SWAT (Liu, et |              |
| works      |       |    |      |    | al. 2007) and |              |
| including  |       |    |      |    | to AnnAGNPS   |              |
| extension  |       |    |      |    | (Yuan et al., |              |
|            |       |    |      |    | 2007)         |              |
|            |       |    |      |    |               |              |
|            |       |    |      |    | Adding        |              |
|            |       |    |      |    | pesticide     |              |
|            |       |    |      |    | component.    |              |
+------------+-------+----+------+----+---------------+--------------+
| Public     |       |    |      |    | Y             |              |
| Domain     |       |    |      |    |               |              |
| (Y/N)      |       |    |      |    |               |              |
+------------+-------+----+------+----+---------------+--------------+
| Other      |       |    |      |    | Requires      |              |
| relevant   |       |    |      |    | estimates of  |              |
| info       |       |    |      |    | upland        |              |
|            |       |    |      |    | loading       |              |
+------------+-------+----+------+----+---------------+--------------+
| Model      |       |    |      |    | Lowrance,     |              |
| Contact    |       |    |      |    | Ric           |              |
| person     |       |    |      |    | hard.lowrance |              |
|            |       |    |      |    | @ars.usda.gov |              |
+------------+-------+----+------+----+---------------+--------------+

*^1^P-B = Process-based, E = Empirical, Q = Quasi-process-based, S=
Statistical, and C = Conceptual*

References

Bhat, S., Hatfield, K., Jacobs, J., Lowrance, R.R., Williams, R.G. 2007.
Surface runoff contribution of nitrogen during storm events in a
forested watershed: Application of the Riparian Ecosystem Management
Model (REMM). Biogeochemistry. 85(3):253-262.

Inamdar, S.P., J. M. Sheridan, R. G. Williams, D. D. Bosch, R. R.
Lowrance, L. S. Altier, D. L. Thomas. 1999a. RIPARIAN ECOSYSTEM
MANAGEMENT MODEL (REMM): I. TESTING OF THE HYDROLOGIC COMPONENT FOR A
COASTAL PLAIN RIPARIAN SYSTEM. Transactions of the ASAE. VOL. 42(6):
1679-1690.

Inamdar, S.P., R. R. Lowrance, L. S. Altier, R. G. Williams, R. K.
Hubbard. 1999b. RIPARIAN ECOSYSTEM MANAGEMENT MODEL (REMM): II. TESTING
OF THE WATER QUALITY AND NUTRIENT CYCLING COMPONENT FOR A COASTAL PLAIN
RIPARIAN SYSTEM. Transactions of the ASAE. VOL. 42(6): 1691-1707.

Liu, Y., Yang, W, Wang, X. 2007. GIS-BASED INTEGRATION OF SWAT AND REMM
FOR ESTIMATING WATER QUALITY BENEFITS OF RIPARIAN BUFFERS IN
AGRICULTURAL WATERSHEDS. Transactions of the ASABE, 50(5):1549-1563.

Yuan, Y., Bingner, R.L., Williams, R.G., Lowrance, R.R., Bosch, D.D.,
Sheridan, J.M. 2007. Integration of AnnAGNPS and REMM for watershed
riparian buffer system assessment. International Journal of Sediment
Research, 22(1): 60-69.

**LESSONS ON FOREST WATERSHEDS AND NUTRIENTS\
WITH AN EMPHASIS ON WESTERN US STUDIES**[^1]

George G. Ice, NCASI; Matthew W. McBroom, SFASU;\
V. Cody Hale, OSU; John Gravelle, UI; and John D. Stednick, CSU

The effect of forest management activities on nutrient levels has long
been an issue for the forestry community. Attention was heightened with
development of Total Maximum Daily Load (TMDL) assessments and the need
to predict load contributions from alternative management activities.
Here we summarize some lessons learned about forest watersheds and
nutrients, focusing on key western studies including the Mokelumne River
in California; Tualatin River, Alsea Watersheds, and H.J. Andrews
Experimental Forest in Oregon; Mica Creek Experimental Watershed in
Idaho; and Alto Watersheds in Texas. These studies and companion work
from other regions show that:

-   Geology and other intrinsic site factors, such as vegetation, often
    predetermine the nutrient status of runoff from forest watersheds.

-   Water quality standards proposed for nutrients may be unachievable
    even for least-impaired watersheds.

-   Specific practices, such as prescribed burning or timing of
    fertilizer application, can moderate or increase potential nutrient
    responses to forest management activities.

-   Natural disturbance events can also affect nutrient loads from a
    watershed.

-   In some cases nutrient responses to management practices, such as
    buffers, may be counter-intuitive if in-stream biological uptake is
    not considered.

-   In-stream nutrient dynamics are complex, and contributing source
    areas can be variable but appear to display consistent patterns.

-   Biological responses to nutrient concentrations are highly variable
    and depend on the forms of nutrients, light levels, residence times,
    turbulence, and other factors.

**INTRODUCTION**

Concerns about the impacts of forest management activities on nutrient
runoff go back at least to watershed experiments at Hubbard Brook, New
Hampshire, in the 1960s. In those experiments, forest clearcutting and
repeated applications of herbicides to suppress regrowth resulted in
elevated nutrient losses from the watershed (Likens et al. 1970).
Concerns about forest management effects on nutrients were later
heightened when TMDL assessments began to protect beneficial uses and
address impaired waterbodies that did not meet water quality standards.
Watershed planners developing TMDLs called for load factors and other
tools to assess nutrient contributions from alternative management
practices (Ice 1999). Guidelines for ecoregion-based nutrient criteria
from the United States Environmental Protection Agency stimulated the
USDA Forest Service and the National Council for Air and Stream
Improvement, Inc. (NCASI) to fund a synthesis of forest watershed data
on nutrients by Dr. Dan Binkley of Colorado State University (Binkley
2001). That review found that runoff from many reference and
least-impaired forested watersheds could not meet the ecoregion-based
guidelines (Ice and Binkley 2003). Those finding are confirmed by recent
forest watershed research across the country.

Given the long-standing and continuing concerns about nutrient responses
to forest activities, it is important to review some key lessons based
on past watershed monitoring. Models that can incorporate these lessons
are likely to be more powerful tools to help explain the consequences of
alternative management choices.

**ALSEA WATERSHED, OREGON**

The Alsea Watershed Study was the first in the US to look at the effects
of forest practices on runoff, water quality, fish habitat, and
biological response simultaneously (Moring 1975; Stednick 2008). The
study included a control watershed (Flynn Creek), and two treated
watersheds: one 25% patch cut with buffers left around fish-bearing
streams (Deer Creek) and one completely clearcut without riparian
buffers (Needle Branch). After harvesting the clearcut basin was
broadcast burned. Nitrate-N flux (discharge and concentration) initially
increased about fivefold in Needle Branch. Deer Creek, with patch
cutting and buffer strips around the fish-bearing reaches, showed no
change in nitrate-N flux. Monitoring after harvest showed recovery of
nutrient concentrations in Needle Branch. However, Flynn Creek (the
control watershed) had higher nitrate-N concentrations than either of
the treated watersheds before and after initial harvest. The high
nitrate-N in Flynn Creek was believed to result from the red alder
(*Alnus rubra*) stands (a nitrogen fixing species) that covered parts of
the basin. Closer inspection of the sources of elevated nitrate-N in
Flynn Creek found that some subbasins exhibited especially high
concentrations. Ongoing work (Hale 2007) found patterns in nutrient
concentrations for basin tributaries that persisted throughout the year.
Hale also found a long-term increase in nitrate-N concentrations for
Needle Branch that is believed to result from development of a riparian
alder stand after the initial harvest. He also confirmed persistent
spatial patterns of nitrate concentrations throughout these watersheds
and a seasonal trend, with highest concentrations during the fall and
declining levels over the rest of the year.

**H.J. ANDREWS EXPERIMENTAL FOREST, OREGON**

A watershed experiment in the H.J. Andrews Experiment Forest was
contemporary to the study in the Alsea Watersheds. H.J. Andrews
Watershed 1 received the most severe treatment, with complete
clearcutting of the basin without a riparian buffer. That clearcutting
caused little, if any, increase in nitrate-N until after a prescribed
burn (Figure 1).

Dr. Sherri Johnson, USDA Forest Service Pacific Northwest Research
Station, is summarizing nutrient findings for the watershed studies
conducted at the H.J. Andrews Experimental Forest and is involved in a
synthesis of lessons from the H.J. Andrews and other long-term research
watersheds.

![](media/image2.png){width="4.520833333333333in" height="2.625in"}

Figure 1. Nitrate-N Response to Clearcutting and a Broadcast Prescribed
Burn\
in the H.J. Andrews Experiment Forest Watershed 1 (Fredricksen 1973)

**MOKELUMNE RIVER, CALIFORNIA**

The 512 mi^2^ Mokelumne River watershed in the central Sierra Nevada
Mountains of California provides both timber from managed timberlands in
the upper basin and water for electrical power generation and municipal
water supplies (Costick et al. 1996). Concerns were raised that
increased forest management activities were negatively affecting water
quality in Pardee and Camanche Reservoirs at the bottom of the
watershed. A synoptic (source-search) survey was conducted by scientists
from the University of California at Davis to determine sources of
nitrogen (N) contributing to reservoir eutrophication (Dahlgren 1996).
Holloway et al. (1998) found that 90% of nitrate-N came from the lower
10% of the basin, below commercial timberlands. Metasedimentary rock
rich in total nitrogen (TN) and organic N was found to be the source of
elevated nitrate concentrations and loads in streamwater runoff. Annual
variations in blue-green algae observed in Camanche Reservoir were
attributed to rates of timber harvest in the basin. Later, water yield
from the basin (which relates to residence time in the reservoir) was
found to explain these annual variations (Costick et al. 1996). A recent
study by Schoenholtz (2007) found that streams adjacent to soils with
high TN, labile N, and poor drainage with low amounts of coarse material
had the highest dissolved N concentrations and were the most susceptible
to increased concentrations from management applications.

**TUALATIN RIVER, OREGON**

The Tualatin River was the first watershed in Oregon to have a TMDL
assessment. A key water quality concern was the development of nuisance
algae populations in the summer, believed to result from excessive
phosphorus (P) concentrations. Forest management occurs in the
headwaters, so forest load allocations were proposed. In Oregon, the
Forest Practices Act regulates commercial forestry operations, and the
Board of Forestry was reluctant to accept load allocations without a
critical review. Degenhart and Ice (1996) described forest management
options considered for the Tualatin River and monitoring to determine
patterns in nutrient concentrations coming from managed forests. It was
found that P concentrations did not differ between basins with a range
of recent harvest levels. Instead, geology was found to be the key
factor controlling P concentrations. A USGS report (Kelly et al. 1999)
concluded:

> Because large natural supplies of highly mobile phosphorus exist in
> the upper 500 feet of valley-fill sediments throughout the Tualatin
> Basin, groundwater in the basin is naturally enriched with phosphorus.
> While improvement in wastewater treatment efficiencies and land
> management have resulted in significant reduction in nutrient
> concentrations in the Tualatin River, phosphorus concentrations
> continue to exceed TMDL criterion concentrations. The presence of
> significant geologic sources of phosphorus in the basin will confound
> the achievement of current criteria for phosphorus in the Tualatin
> River and its tributaries.

**MICA CREEK EXPERIMENTAL WATERSHED, IDAHO**

Since 1992 the Mica Creek Experimental Watershed in northern Idaho has
been the site of a study testing the effectiveness of the Idaho Forest
Practices Act regulations. The study is designed to look at the
propagation of impacts as they cumulatively move downstream by having
stations located at several sites downstream of treated basins. The most
notable change following harvesting occurred for nitrate/nitrite-N for a
clearcut basin, compared to a smaller increase for a partially harvested
basin. Interestingly, the basin showing the largest response had always
displayed elevated nitrate-N compared to the rest of the Mica Creek
Experimental Watershed. This was found to result from riparian alder.
Impacts in the headwaters were diluted as they moved downstream to lower
sampling sites (Figure 2). These are low nutrient streams, and even the
basin with the largest increase never had a nitrate-N concentration
reaching 1 mg/L. The nutrient data collected at Mica Creek also provide
more information to support the findings that nutrient concentrations in
relatively undisturbed forest watersheds are much lower than in
watersheds associated with other land uses (Omernick 1976).

![](media/image3.wmf){width="6.490972222222222in"
height="2.8958333333333335in"}

Figure 2. Nitrate/Nitrite-N Concentrations during Calibration, Post-Road
Construction, and Post-Timber Harvest Periods for F1 (clearcut); F4 (
includes flow from F1, F2 (partial harvest), and F3 (control) basins);
and F7 (farther downstream) watersheds (Gravelle et al. in prep)

**ALTO WATERSHEDS, TEXAS**

The Alto Watersheds in East Texas allowed comparisons of water quality
impacts from contemporary timber harvesting and regeneration practices
to impacts from historic management practices and more intensive
management regimes. Nine small (about 2.5 ha) and four large (70 to 135
ha) watersheds were studied. Baseflow nutrient concentrations remained
largely unchanged. However, baseflow samples for both the pre- and
post-treatment periods frequently exceeded EPA's Ecoregion IX proposed N
and P criteria, indicating that these standards may not be appropriate
for dynamic headwater streams. McBroom et al. (2008) found small
increases in N and P runoff in stormwater, especially the first year
after timber harvesting or fertilizer applications. P and N did not
increase where DAP was applied to a five year old stand, but a small
increase in nutrients was observed for a fertilizer application to a
recently clearcut stand (large watershed response). There was high
variability in small basin responses in terms of the amounts and forms
of nutrient increases, but in all cases the changes in nutrient loads
were a small fraction of the annual input levels (atmospheric deposition
or fertilizer application) and were not believed to be biologically
significant. One additional lesson learned at the Alto Watersheds was
the effect of large storm systems on nutrient response. In early June
2001 Tropical Storm Allison dumped 11.8 cm of rain on saturated soils,
generating 73 and 95% of the annual flow and sediment, respectively, for
the year within a few hours (McBroom et al. 2003). This pre-treatment
event also produced a greater nutrient loss than clearcutting and
fertilization did on most of the watersheds, illustrating the
sensitivity of nutrient response in these systems to large stormflows.

**BIOLOGICAL RESPONSES TO NUTRIENTS**

A key factor determining biological responses in many of these studies
is the characteristics of the receiving water. In the case of the
Mokelumne River, residence time resulting from the annual runoff pattern
appears to affect algae buildup in the key downstream reservoir (Costick
et al. 1996). In the Tualatin River, Willey and LeSieur (1990) described
a stream system that was highly sensitive to algal outbreaks:

> ...most of the time and most of the \[stream\] distance, the water
> runs slowly because of the very gradual drop in the river's elevation.
> In one, 24-mile stretch, the river drops only 12 in. In the summer,
> the Tualatin often looks and behaves more like a pond than a river.

Stewart (1997) found that:

> When samples taken on the same date were compared, water within the
> forestry land use class remained of high quality and free of algal
> blooms, although soluble and total P concentrations were the same as
> those found in other stream segments experiencing blooms and
> degradation. These observations, coupled with the high quality of the
> spring water, reflect the importance of additional variables on
> surface water quality, such as light, temperature, kinetic energy
> (flow velocity), and healthy riparian areas.

Stark et al. (2001) found higher nitrate-N concentrations in streams
with forest cover in the Upper Mississippi Basin. This relationship is
believed to result from shade limiting biological uptake by aquatic
plants.

Nutrient form is also important in determining biological responses
observed in lakes or streams. Lee (2002) noted that while total N and
total P have been proposed to set water quality criteria and estimate
biological response, a large fraction of those nutrients may be
unavailable for biological activity. For example, Lee found that "Aged
organic-N can be highly refractory... where only a limited amount will
convert to algal-available N." Lee also noted that either N or P can be
limiting, thus determining the potential response to a change in
concentration.

**NATURAL DISTURBANCE**

We often model management impacts against recently undisturbed systems,
but all forest ecosystems are subject to natural disturbance regimes.
Typical disturbances include floods, fires, windstorms, landslides, and
insect and disease outbreaks. Monitoring results from the Alto
Watersheds for Tropical Storm Allison (McBroom et al. 2003) demonstrated
just how significant extreme events can be for nutrient outputs from a
watershed. Ice and Schoenholtz (2003) described water quality responses
to some disturbance events. For example, they found that fire is
generally thought to increase nutrient concentrations and loads in
nearby streams as a result of disrupted nutrient cycling, accelerated
mineralization of organic matter, and runoff of ash and sediment to
streams. Similarly, Eshleman et al. (1998) and Fiscus (1998) showed that
N concentrations and loads can increase in streams where defoliating
insect outbreaks occur (Figure 3). This can involve disruption of
nutrient recycling, direct deposition of N-rich frass in streams, and
even a change in the rate of detritus processes (Hutchens and Benfield
2000). Eshleman et al. (2004) described an attempt to validate a
regional disturbance model for predicting N leakage from mid-Appalachian
forests that would result from an insect defoliation episode based on a
unit nitrogen export response function (UNERF).

![](media/image4.png){width="5.208333333333333in"
height="2.4270833333333335in"}

Figure 3. Flow-Weighted Annual Concentration of Nitrate in White Oak
Run, Virginia,\
Following a Gypsy Moth Outbreak in 1991 (Fiscus 1998)

**CONCLUSIONS**

Modeling efforts to help forest managers and watershed specialists
assess alternative management strategies need to consider lessons
learned from these and other watershed studies. Geology and vegetation
can have major influences on water quality. Disturbance events can
disrupt nutrient cycling and, in some cases, increase mineralization and
nutrient availability for leaching or runoff. Even in recently disturbed
systems most inputs of N and P are retained in the watershed. For
established stands, retention of inputs from fertilizer applications
appears to be even greater. Measured impacts are attenuated downstream
by dilution and nutrients may also be taken up by instream primary
productivity. Biological responses are complex and depend on factors
such as temperature, turbulence, and light availability, as well as
total nutrient concentrations and whether the nutrients are in forms
that are bioavailable and limiting to aquatic plant growth.

**REFERENCES**

Binkley, D. 2001. *Patterns and processes of variation in nitrogen and
phosphorus concentrations in forested streams*. Technical Bulletin No.
836. Research Triangle Park, NC: National Council for Air and Stream
Improvement, Inc.

Costick, L., Monk, R., and Ice, G. 1996. Monitoring and forest
management activities designed to address water quality concerns in the
Mokelumne River basin. D-19 to D-29 in *Proceedings of the 1995 NCASI
West Coast Regional Meeting*. Special Report No. 96-04. Research
Triangle Park, NC: National Council for Air and Stream Improvement, Inc.

Dahlgren, R.A. 1996. The use of a source-search study to address
concerns about eutrophication of lakes in the Mokelumne River basin.
D-17 to D-19 in *Proceedings of the 1995 NCASI West Coast Regional
Meeting*. Special Report No. 96-04. Research Triangle Park, NC: National
Council for Air and Stream Improvement, Inc.

Degenhardt, D., and Ice, G. 1996. Forest management options to control
excess nutrients for the Tualatin River, Oregon. D-2 to D-17 in
*Proceedings of the 1995 NCASI West Coast Regional Meeting*. Special
Report No. 96-04. Research Triangle Park, NC: National Council for Air
and Stream Improvement, Inc.

Eshleman, K.N., Fiscus, D.A., Castro, N.M., Webb, J.R., and Herlihy,
A.T. 2004. Regionalization of disturbance-induced nitrogen leakage from
mid-Appalachian forests using a linear systems model. *Hydrological
Processes* 18(14):2713-2725.

Eshleman, K.N., Morgan R.P., II, Webb, J.R., Deviney, F.A., and
Galloway, J.N. 1998. Temporal patterns of nitrogen leakage from
mid-Appalachian forested watersheds: Role of insect defoliation. *Water
Resources Research* 34(4):2005.

Fiscus, D. 1998. Integrative study links gypsy moth defoliation,
nitrogen leakage and surface water quality in Mid-Atlantic Region.
*NWQEP Notes*, No. 90. Raleigh, NC: North Carolina State University,
North Carolina Cooperative Extension Service. Available at:
<http://www.bae.ncsu.edu/programs/extension/wqg/issues/90.html>.

Fredriksen, R.L. 1973. Impact of forest management on stream water
quality in western Oregon. 37 to 50 in *Pollution abatement and control
in the forest products industry, 1971-1972*. Portland, OR: United States
Department of Agriculture Forest Service.

Gravelle, J., Ice, G.G., Link, T.E., and Cook, D. In preparation.
Nutrient concentration patterns in a northern Idaho watershed before and
after timber harvest.

Hale, V.C. 2007. *A physical and chemical characterization of stream
water draining three Oregon Coast Range catchments*. MS thesis, Oregon
State University, Corvallis, OR.

Holloway, J.M, Dahlgren, R.A., Hansen, B., and Casey, W.H. 1998.
Contribution of bedrock nitrogen to high nitrate concentrations in steam
water. *Nature* 395:785-788.

Hutchens, J.J., Jr., and Benfield, E.F. 2000. Effects of forest
defoliation by gypsy moth on detritus processing in southern Appalachian
streams. *American Midland Naturalist* 143(2):397‑404.

Ice, G.G. 1999. Technical problems associated with the use of Total
Maximum Daily Load limits for forest practices--Revisted. 37 to 44 in
Olsen, D.S, and Potyondy, J.P. \[Eds.\]. *Wildland Hydrology*. TPA-99-3.
Herndon, VA: American Water Resources Association.

Ice, G., and Binkley, D. 2003. Forest streamwater concentrations of
nitrogen and phosphorus. *Journal of Forestry* 101(1):21-28.

Ice, G.G., and Schoenholtz, S.H. 2003. Understanding how extremes
influence water quality: Experience from forest watersheds.
*Hydrological Science and Technology* 19(1-4):99‑108.

Kelly, V.J., Lynch, D.D., and Rounds, S.A. 1999. *Sources and transport
of phosphorus and nitrogen during low-flow conditions in the Tualatin
River, Oregon, 1991-1993*. Water-Supply Paper 2465-C. United States
Geological Survey. 94 p.

Lee, G.F. 2002. Evaluating nitrogen and phosphorus control in nutrient
TMDLs. *Stormwater* 3(1):10-12,14-16,18,21-22,24.

Likens, G.E., Borman, F.H., Johnson, N.M., Fisher, D.W., and Pierce,
R.S. 1970. Effects of forest cutting and herbicide treatment on nutrient
budgets in the Hubbard Brook Watershed ecosystem. *Ecological
Monographs* 40(1):24-47.

McBroom, M.W., Beasley, R.S., Chang, M., Gowin, B., and Ice, G.G. 2003.
Runoff and sediment losses from annual and unusual storm events from the
Alto Experimental Watersheds, Texas: 23 years after silvicultural
treatments. 607 to 613 in Renard, K.G. et al. (Eds.). *First Interagency
Conference on Research in the Watersheds*. 27--30 October 2003.
Washington, DC: USDA-ARS.

McBroom, M.W., Beasley, R.S., Chang, M., and Ice, G.G. 2008. Water
quality effects of clearcut harvesting and forest fertilization with
best management practices. *Journal of Environmental Quality*
37:114-124.

Moring, J.R. 1975. *The Alsea Watershed Study: Effects of logging on the
aquatic resources of three headwater streams of the Alsea River, Oregon.
Part II - Changes in environmental conditions*. Fish Research Report 9.
Oregon Department of Fisheries and Wildlife.

Omernick, J.M. 1976. *The influence of land use on stream nutrient
levels*. EPA 6000/3-76-014. Washington, DC: United State Environmental
Protection Agency.

Schoenholtz, S.H. 2007. *Managed forests and their role in maintaining
water quality in a multi-land use river basin: Final report 2007*.
Submitted to the Fish and Wildlife in Managed Forest Program, Oregon
State University, Corvallis, OR.

Stark, J.R., Hanson, P.E., Goldstein, R.M., Fallon, J.D., Fong, A.L.,
Lee, K.E., Kroening, S.E., and Andrews, W.J. 2001. *Water quality in the
upper Mississippi River Basin, Minnesota, and Wisconsin, South Dakota,
Iowa, and North Dakota. 1995-1998*. Summary Circular 1211. Reston, VA:
United States Geological Survey.

Stednick, J.D. \[Ed.\]. 2008. *Hydrological and biological responses to
forest practices: The Alsea Watershed Study*. Ecological Studies No.
199. New York: Springer.

Stewart, S. 1997. *Summary of a discussion: The relationship between
land use and surface water phosphorus concentrations*. Special Report
No. 980. Corvallis, OR: Oregon State University Extension Service.

Willey, B.R., and LeSieur, S.A. 1990. The Tualatin River: A commitment
to water quality. *Water Environment and Technology* 81:42-47.

**Comparative Features of Strengths, Weaknesses, Applications, and
Limitation of Five Hydrology and Water Quality Models for Nutrient
Cycling (Fate) and Transport Modeling**

+------------+-------+-----------------+----------+-----+-----+-----+
| **Model    | *     | **Model Name**  |          |     |     |     |
| Features   | *Equa |                 |          |     |     |     |
| and        | tions |                 |          |     |     |     |
| Charact    | (P-B, |                 |          |     |     |     |
| eristics** | E, S, |                 |          |     |     |     |
|            | Q, or |                 |          |     |     |     |
|            | C)    |                 |          |     |     |     |
|            | ^1^** |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
|            |       | **WARMF**       | **DRAINM | **M | **  | **  |
|            |       |                 | OD-NII** | IKE | REM | SWA |
|            |       |                 |          | -SH | M** | T** |
|            |       |                 |          | E** |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Developed  |       | Systech         |          |     |     |     |
| by/at      |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Field      |       | Watershed,      |          |     |     |     |
| and/or     |       | multiple river  |          |     |     |     |
| Watershed  |       | basins w/ lakes |          |     |     |     |
| scale      |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Forest     |       | yes             |          |     |     |     |
| Land Use:  |       |                 |          |     |     |     |
|            |       |                 |          |     |     |     |
| Yes or No  |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Upla       |       | yes             |          |     |     |     |
| nd/Lowland |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Largest    |       | 6000 sq mi      |          |     |     |     |
| area       |       |                 |          |     |     |     |
| applied,   |       |                 |          |     |     |     |
| km^2^      |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Surface    |       | Sheet flow      |          |     |     |     |
| R          |       | Manning         |          |     |     |     |
| unoff/Flow |       |                 |          |     |     |     |
| generation |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Subsurface |       | Darcy's         |          |     |     |     |
| flo        |       |                 |          |     |     |     |
| w/Drainage |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Evapotra   |       | yes             |          |     |     |     |
| nspiration |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Water      |       | yes             |          |     |     |     |
| Table      |       |                 |          |     |     |     |
| Dynamics   |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Nitrogen   |       | yes             |          |     |     |     |
| (N)        |       |                 |          |     |     |     |
| cycling    |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Phosphorus |       | yes             |          |     |     |     |
| (P)        |       |                 |          |     |     |     |
| cycling    |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Carbon (C) |       | yes             |          |     |     |     |
| cycling    |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| In-stream  |       | yes             |          |     |     |     |
| N          |       |                 |          |     |     |     |
| transport  |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| In-stream  |       | yes             |          |     |     |     |
| P          |       |                 |          |     |     |     |
| transport  |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| In-stream  |       | yes             |          |     |     |     |
| C          |       |                 |          |     |     |     |
| transport  |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Riparian   |       | yes             |          |     |     |     |
| process    |       |                 |          |     |     |     |
| for        |       |                 |          |     |     |     |
| hydrology  |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Riparian   |       | yes             |          |     |     |     |
| process    |       |                 |          |     |     |     |
| for        |       |                 |          |     |     |     |
| nutrient   |       |                 |          |     |     |     |
| cycling    |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Primary    |       | Meteorology,    |          |     |     |     |
| Input Data |       | fertilizer      |          |     |     |     |
|            |       | application,    |          |     |     |     |
|            |       | productivity    |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Temporal   |       | Hourly, daily   |          |     |     |     |
| Scale      |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| U          |       | Jack-knife      |          |     |     |     |
| ncertainty |       |                 |          |     |     |     |
| Analysis   |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Model      |       | EPRI, EPA,      |          |     |     |     |
| Supported  |       | Systech         |          |     |     |     |
| by         |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| P          |       | Yes. forest     |          |     |     |     |
| ossibility |       | fire model,     |          |     |     |     |
| of         |       | GCM, Airshed    |          |     |     |     |
| Linkage;   |       | model,          |          |     |     |     |
| Y/N        |       | CE-QUAL2,       |          |     |     |     |
|            |       | Estuary Model   |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Most       |       | Mica Creek      |          |     |     |     |
| recent     |       | Watershed       |          |     |     |     |
| published  |       |                 |          |     |     |     |
| paper(s)   |       |                 |          |     |     |     |
| for forest |       |                 |          |     |     |     |
| e          |       |                 |          |     |     |     |
| co-systems |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Recent     |       | 2006, mercury   |          |     |     |     |
| ongoing    |       |                 |          |     |     |     |
| works      |       |                 |          |     |     |     |
| including  |       |                 |          |     |     |     |
| extension  |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Public     |       | yes             |          |     |     |     |
| Domain     |       |                 |          |     |     |     |
| (Y/N)      |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Other      |       |                 |          |     |     |     |
| relevant   |       |                 |          |     |     |     |
| info       |       |                 |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+
| Model      |       | <carl@syst      |          |     |     |     |
| Contact    |       | echenging.com>, |          |     |     |     |
| person     |       |                 |          |     |     |     |
|            |       | <joel@sy        |          |     |     |     |
|            |       | stechwater.com> |          |     |     |     |
+------------+-------+-----------------+----------+-----+-----+-----+

*^1^P-B = Process-based, E = Empirical, Q = Quasi-process-based, S=
Statistical, and C = Conceptual*

# Long Term Data Sets for Forest Hydrologic and Nutrient Fate Modeling in the Southeastern USA 

## D.M. Amatya and Carl Trettin[^2]

**Abstract.** Long term (LT) hydrologic and nutrient cycling data are
essential for advancing the understanding of the physical processes
governing the eco-hydrologic cycle, as base line data for evaluating
impacts of land management practices and land use changes, and for
developing/testing field and watershed scale models that are being used
as decision making tools. Furthermore, the LT data provides a basis for
understanding the inherent natural variability and reducing uncertainty
by more accurate input and parameter estimations. Recent developments in
eco-hydrology will put even more demands on such data as scientists
expand their hydrologic research in conjunction with generating new
hypotheses, conservation of regional eco-systems, and trend analysis
e.g. climate change, water demand. Forests are an important part of the
eco-system. However, there is a limited research done on this eco-system
compared to agricultural landscapes. An estimated 70% of the freshwater
in the United States originates in forests with the headwaters often
occurring in National Forests. Currently there are 18 long-term
Experimental Forest and Range networks (EFR) including the seven LTER
sites within the Forest Service National Forests besides the NSF's NEON
and WATERS sites. Other similar long-term sites include USDA ARS and
USGS stations. Long-term hydrologic data from small, paired,
experimental watersheds at Forest Service Coweeta Hydrologic Laboratory
in North Carolina (one of the LTER sites) integrated with an eco-system
approach have provided basic understanding of eco-hydrological processes
for regional upland forested watersheds (Swank et al., 2001). However,
there are only a few studies done for the pine forest eco-systems that
occur along the lowlands of southeast where 55% of the land is on
forests. Some of the other experimental watersheds in the southeast that
are worth mentioning are: B.F. Grant Memorial Forest (GA), Santee
Experimental Watersheds (SC), Bradford watersheds (FL), Riparian Wetland
Watershed (VA), Upland Hardwood Lands (AK), Carteret watersheds (NC),
Isaac Creek watershed (NC), Parker Tract watersheds (NC), Bell Baruch
Watersheds (SC), Trice Forest (SC). Ice and Stednick (2004), Chescheir
et al. (2003), Sun et al (2001), Binkley (2001); Shepard (1994) document
details of hydrologic and water quality studies conducted on various
types of forest ecosystems found in the southeastern USA. Researchers
involved in eco-hydrologic modeling are encouraged to develop and test
their models using multi-site and multiple years of data for increasing
the confidence in model predictions and their wider applications.
Although most of the studies (Yapo et al. 1996) emphasize in a LT (\> 8
yrs) data for a better model calibration some (Gan and Biftu in Duan et
al (2003) report that at least one year of data may be adequate given
enough information. They reported that model structure and data quality
(measurement uncertainties/QAQC) are more crucial than the model
complexity and data length. Similarly, studies have shown that accurate
simulation of water flux is crucial for simulating the nutrient fate and
transport. However, only a limited data exists for nutrient cycling
processes in terrestrial ecosystems compared to the nutrient
concentrations of streams and water bodies (Binkley, 2001). A
comprehensive nutrient fate and transport modeling requires an extensive
data on both the processes as well as the stream water chemistry besides
the hydrology data (e.g. flow, ET, WT). U.S. Nitrogen Plan (2004)
(Holland et al., 2005) also emphasizes on an interdisciplinary approach
and a LT base line data for addressing regional and global N cycling
issues in terrestrial, atmospheric, and aquatic systems. This
presentation provides the scope of the monitoring, available data and
past studies for a long-term USDA Forest Service coastal forest
experimental station in South Carolina Amatya et al. (2007) and a
20-year old monitoring station on a managed pine forest owned by
Weyerhaeuser Company in coastal North Carolina Amatya et al. (2006).

**References:**

Amatya, D.M., C.A. Harrison, and C.C. Trettin. 2007. Water Quality of
Two First-order Forested Watersheds in Coastal South Carolina. In Proc.,
*ASABE sponsored 4^th^ TMDL specialty conference*, San Antonio, TX,
March 11-14, 2007, pp: 507-515.

Amatya, D.M., R.W. Skaggs, and J.W. Gilliam. 2006. Long-term hydrology
and water quality of a drained loblolly pine plantation in coastal North
Carolina. *In Proc. of the ASABE-Weyerhaeuser sponsored Int'l Conference
on Hydrology and Management of Forested Wetlands*, eds. Williams and
Nettles, New Bern, North Carolina, April 8-12, 2006.

Binkley, D. 2001. Patterns and processes of variation in nitrogen and
phosphorus concentrations in forested streams. *NCASI Technical Bulletin
#836*, 147p, Research Triangle Park, NC.

Chescheir, G.M., M.E. Lebo, D.M. Amatya, J.E. Hughes, J.W. Gilliam, R.W.
Skaggs, and R.B. Herrmann. 2003.Hydrology and Water Quality of Forested
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[^1]: Paper presented at the Workshop to Develop a Comprehensive Forest
    Nutrient Cycle and Export Modeling Package, Santee Experimental
    Forest, Cordesville, SC.

[^2]: Research Hydrologist and Team Leader/Soil Scientist, USDA Forest
    Service, Southern Research Station, Cordesville, SC; Contact: D.M.
    Amatya; Tel: 843-336-5612, Email: damatya@fs.fed.us.