U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2009–5106 

Prepared in cooperation with the Kane County Department of Environmental and Building 

Management and the Illinois Department of Natural Resources–Office of Water Resources 

Effect of Detention Basin Release Rates on Flood Flows—

Application of a Model to the Blackberry Creek Watershed 

in Kane County, Illinois 
Cover: Detention basin and inlet at Fox Hill Lane at the upper part of the East Run tributary of Blackberry Creek in North Aurora, 

Illinois, 2002. (Photograph by U.S. Geological Survey personnel.) 
Effect of Detention Basin Release Rates 

on Flood Flows—Application of a Model 

to the Blackberry Creek Watershed in 

Kane County, Illinois 

By David T. Soong, Elizabeth A. Murphy, and Timothy D. Straub 

Prepared in cooperation with the Kane County Department of Environmental and 

Building Management and the Illinois Department of Natural Resources–Office 

of Water Resources 

Scientific Investigations Report 2009–5106 

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Soong, D.T., Murphy, E.A., and Straub, T.D., 2009, Effect of detention basin release rates on flood flows—Application 

of a model to the Blackberry Creek Watershed in Kane County, Illinois: U.S. Geological Survey Scientific Investigations 

Report 2009–5106, 33 p. 
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................2

Previous Studies ...................................................................................................................................2

Release Rates in Northeastern Illinois.....................................................................................2

Release Rates in Continuous Hydrologic Simulation.............................................................3

Detention Modeling.......................................................................................................................................3

Detention Basin Volume Estimation...................................................................................................3

Multiple Release Rates........................................................................................................................4

Blackberry Creek Detention Modeling Case Study .................................................................................5

Data.........................................................................................................................................................6

Methods..................................................................................................................................................6

Simulation Results ..............................................................................................................................10

Summary and Conclusions.........................................................................................................................28

Acknowledgments.......................................................................................................................................28

References Cited..........................................................................................................................................28

Appendix 1. Flood quantiles estimated for selected recurrence intervals based on 

Hydrological Simulation Program–FORTRAN analysis for the 1996 land 

uses, 2020 projected land uses without detention basins, and 2020 projected 

land uses with detention basins and release rates of 0.08, 0.10, and 0.12 cubic 

feet per second per acre at subbasins of the Blackberry Creek watershed in 

Kane County, Illinois...........................................................................................................32 

Figures

1. Graph showing the differences in storage volume required by a linear slot 

volume-discharge relation and an orifice-controlled storage volume-discharge 

relation............................................................................................................................................4

2. Graph showing the detention storage volume required per acre to achieve a 

0.08, 0.10, or 0.12 cubic feet per second per acre detention release rate for 

different amounts of impervious area .......................................................................................5

3. Map showing the location of the Blackberry Creek watershed in Kane County, 

Illinois..............................................................................................................................................5

4. Graph showing the comparison of flood frequency curves estimated at the 

U.S. Geological Survey streamflow-gaging station at Yorkville, Illinois, from 

Argonne National Laboratory precipitation data from 1950–99 and 1950–2003.................6

5. Maps showing the 1996 and projected 2020 land uses for the Kane County 

portion of the Blackberry Creek watershed.............................................................................7

6. Map showing the subbasins and naming system used in the Hydrological 

Simulation Program–FORTRAN model for the Blackberry Creek watershed 

in Kane County, Illinois.................................................................................................................8
iv

7–21. Graphs showing comparison of flood frequencies and selected storm hydrographs 

simulated for 1996 and 2020 land uses and selected detention basin release rates:

7. Downstream from Route 38 Branch tributary to Blackberry Creek, 

Kane County, Illinois ..........................................................................................................13

8. Downstream from Elburn Run tributary to Blackberry Creek, 

Kane County, Illinois ..........................................................................................................14

9. Downstream from Seavey Road Run tributary to Blackberry Creek, 

Kane County, Illinois ..........................................................................................................15

10. Downstream from Prestbury Branch tributary to Blackberry Creek, 

Kane County, Illinois ..........................................................................................................16

11. Downstream from Lake Run tributary to Blackberry Creek, 

Kane County, Illinois ..........................................................................................................17

12. Downstream from East Run tributary to Blackberry Creek, 

Kane County, Illinois ..........................................................................................................18

13. Downstream from Aurora Chain-of-Lakes tributary to Blackberry Creek, 

Kane County, Illinois ..........................................................................................................19

14. On Blackberry Creek at Route 47 downstream from the junction with 

Elburn Run (subbasin 220), Kane County, Illinois..........................................................20

15. On Blackberry Creek at Route 47 downstream from the junction with 

Seavey Road Run (subbasin 230), Kane County, Illinois..............................................21

16. On Blackberry Creek near the Village of Sugar Grove (subbasin 236), 

Kane County, Illinois ..........................................................................................................22

17. On Blackberry Creek upstream from the junction with Lake Run 

(subbasin 240), Kane County, Illinois ..............................................................................23

18. On Blackberry Creek upstream from the junction with East Run 

(subbasin 250), Kane County, Illinois ..............................................................................24

19. On Blackberry Creek downstream from the junction with East Run 

(subbasin 260), Kane County, Illinois ..............................................................................25

 20. On Blackberry Creek upstream from the junction with 

Aurora Chain-of-Lakes (subbasin 265), Kane County, Illinois.....................................26

21. On Blackberry Creek (subbasin 270), at the Kane and 

Kendall County, Illinois, line .............................................................................................27 
v

Tables

1. Land-use categories from the 2005 Blackberry Creek flood-hazard study 

and associated 2020 land-use categories................................................................................6

2. Drainage area, impervious area determined from the 1996 land-use map, 

and projected additional impervious area by 2020 for tributary subbasins 

of the Blackberry Creek watershed in Kane County, Illinois.................................................9

3. Drainage area, impervious area determined from the 1996 land-use map, 

and projected additional impervious area by 2020 along the main stem of 

the Blackberry Creek watershed in Kane County, Illinois....................................................10

4. Tributaries in the Blackberry Creek watershed, Kane County, Illinois, with 

numerical codes for the most downstream subbasin, and figure numbers 

where the simulation results are shown ................................................................................11

5. Detention basin release-rate evaluation locations along the main stem of 

Blackberry Creek in Kane County, Illinois, numerical codes for the subbasin 

upstream from each location, and figure numbers where the simulation 

results are shown .......................................................................................................................11

6. Ratios of peak flow and drainage area for pre- and postdevelopment 

scenarios at selected locations in the Blackberry Creek watershed, 

Kane County, Illinois ...................................................................................................................12 
vi

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 0.4047 hectare (ha)

square mile (mi2) 259.0 hectare (ha)

Volume

cubic foot (ft3) 0.02832 cubic meter (m3) 

acre-foot (acre-ft) 1,233 cubic meter (m3) 

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88). 

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83). 

Conversion Factors 

Acronyms and Abbreviations 

AMS annual maximum series

CBBEL Christopher B. Burke Engineering, Ltd.

HSPF Hydrological Simulation Program–FORTRAN

KCDEM Kane County Department of Environmental and Building Management

MWRD Metropolitan Water Reclamation District 

NIPC Northeastern Illinois Planning Commission

USGS U.S. Geological Survey

WY water year

ft3/s-acre cubic foot per second per acre
Abstract

The effects of stormwater detention basins with specified release rates are examined on the watershed scale with 

a Hydrological Simulation Program–FORTRAN (HSPF) 

continuous-simulation model. Modeling procedures for specifying release rates from detention basins with orifice and weir 

discharge configurations are discussed in this report. To facilitate future detention modeling as a tool for watershed management, a chart relating watershed impervious area to detention 

volume is presented. The report also presents a case study of 

the Blackberry Creek watershed in Kane County, Ill., a rapidly 

urbanizing area seeking to avoid future flood damages from 

increased urbanization, to illustrate the effects of various 

detention basin release rates on flood peaks and volumes and 

flood frequencies. The case study compares flows simulated 

with a 1996 land-use HSPF model to those simulated with 

four different 2020 projected land-use HSPF model scenarios—no detention, and detention basins with release rates of 

0.08, 0.10, and 0.12 cubic feet per second per acre (ft3/s-acre), 

respectively. Results of the simulations for 15 locations, 

which included the downstream ends of all tributaries and 

various locations along the main stem, showed that a release 

rate of 0.10 ft3/s-acre, in general, can maintain postdevelopment 100-year peak-flood discharge at a similar magnitude to 

that of 1996 land-use conditions. Although the release rate is 

designed to reduce the 100-year peak flow, reduction of the 

2-year peak flow is also achieved for a smaller proportion of 

the peak. Results also showed that the 0.10 ft3/s-acre release 

rate was less effective in watersheds with relatively high 

percentages of preexisting (1996) development than in watersheds with less preexisting development.

Introduction

Urbanization increases impervious surfaces in residential, commercial and industrial areas and alters the hydrologic response of a watershed to rainfall. Altered hydrologic 

responses include reduced interception by vegetation and 

reduced detention capacity due to elimination of depressional 

storage. Consequently, storm runoff occurs faster and can 

have larger peak-discharges and runoff volumes from developed areas. Runoff corresponding to short-duration rainfall 

appears more frequently and less water infiltrates the soil, 

which decreases ground-water storage capacities in developed 

landscapes and alters baseflows (Konrad, 2003; Bedient and 

Huber, 2002). Urbanization can also impact water quality; 

storm runoff from urban areas may contain high concentrations of suspended solids and chemicals, such as nitrogen, 

phosphorus, trace elements, and organics, or oils and greases 

(Sherwood, 2001). Increases in flood-peak magnitude, floodpeak frequency, and runoff volumes, along with the resulting 

increases in sediment and pollutant loads, can cause more 

flooding, erosion, water pollution, and destruction of stream 

habitat. 

Stormwater facilities, such as detention basins, retention 

basins, and infiltration areas, store storm runoff on site and 

reduce runoff rates from the site. Among stormwater facilities, 

detention or retention basins are the most widely used in practice. A detention basin temporarily stores storm runoff, and 

the stored storm runoff is later released downstream through 

a flow-control structure that regulates the rate of release. A 

retention basin retains a specified amount of stormwater runoff 

without releasing it except by means of evaporation, infiltration, emergency bypass, or pumping. Infiltration areas reduce 

runoff by moving water from the surface into the ground-water 

system through permeable soils. Devices or plants that filter 

or remove sediment, excess nutrients, and toxic chemicals 

can be installed on detention basins to enhance water-quality 

protection. Basins can be designed for multiple purposes 

and integrated into neighborhoods for open space and recreation, aesthetics, and wildlife-habitat enhancement (King 

County Stormwater Services, 2008). However, a detention 

basin can control runoff effectively only if its total volume 

is not exceeded. Once flows overtop the basin, the runoff is 

no longer controlled and damaging downstream flows are 

normally assumed. Thus basin volume is the ultimate determinant of detention basin performance. The primary factors for 

determining the basin volume are the contributing drainage 

area, basin release rate, local soil, hydrological, climatologic 

characteristics, and time to release the stored runoff.

Effect of Detention Basin Release Rates on Flood Flows—

Application of a Model to the Blackberry Creek Watershed 

in Kane County, Illinois 

By David T. Soong, Elizabeth A. Murphy, and Timothy D. Straub 
2 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Runoff from a natural watershed is inherently distributed 

in time and space, unlike the water released from a detention 

basin, which enters the stream at one location. Release rate is 

the amount of flow that a control outlet structure is designed 

to pass in a given duration. The release rate varies with the 

type of outlet structure implemented, such as a weir or orifice. 

Release rates are determined by the size of the contributing 

watershed area and the chosen goal of the detention, either 

mitigation of the effects of peak-flood discharge or duration. 

Typical release-rate design requirements do not consider 

modifications to the shape of the outflow hydrographs, such as 

longer postdevelopment flood-peak discharge than predevelopment flood-peak discharge given the increased volume and 

the timing of released flow. The prolonged release may cause 

flooding to continue or worsen in larger drainage systems. 

It is challenging to design release rates that produce outflow 

emulating storm events that vary both in intensity and duration 

and extend over long periods of time but still satisfy floodpeak reduction and flow-duration requirements (King County 

Stormwater Services, 2008).

The Kane County Department of Environmental and 

Building Management (KCDEM) developed a stormwater 

ordinance to manage continuing growth and to protect natural 

resources in Kane County (Kane County Stormwater Management, 2005). The ordinance specifies that detention storage 

should be constructed in all new development areas in the 

county and that detention basins should have a release rate 

set at 0.1 cubic feet per second per acre of developed area 

(ft3/s‐acre) for controlling the 100-year flood. However, uncertainty remains about the extent of protection given by this 

release rate on the watershed scale. The U.S. Geological Survey (USGS), in cooperation with the KCDEM, undertook this 

study to determine the effect of detention basin release rates 

on flood flows for stormwater management in the Blackberry 

Creek watershed in Kane County.

Purpose and Scope

The purpose of this report is to document the modeling 

approach used to simulate flows from detention basins with 

specified release rates. Modeling procedures for specifying 

release rates from detention basins with an orifice and weir 

discharge configuration are discussed. To facilitate future 

detention modeling as a tool for watershed management, a 

chart relating watershed impervious area to detention volume is presented. The report also presents a case study of 

the Blackberry Creek watershed in Kane County, a rapidly 

urbanizing area seeking to avoid future flood damages from 

increased urbanization, to illustrate the effects of various 

release rates on flood peaks and volumes, and the flood 

frequencies. The case study compares flows simulated with a 

1996 land-use Hydrological Simulation Program-FORTRAN 

(HSPF) model (Bicknell and others, 2000) to those simulated 

with four 2020 land-use HSPF model scenarios—no detention, and detention basins with release rates of 0.08, 0.10, and 

0.12 ft3/s-acre, respectively. 

Previous Studies

A literature review on the use of detention release rates in 

northeastern Illinois and the implementation of release rates in 

other HSPF models was completed.

Release Rates in Northeastern Illinois

Communities in northeastern Illinois began adopting stormwater detention requirements in the early 1970s. 

Approximately 80 percent of the municipalities and counties 

in the region have detention requirements for new development (Dreher and others, 1989). Local detention requirements 

vary widely, in terms of storage volumes, release rates, and 

suggested computational requirements. A brief review of 

the establishment of stormwater ordinances in areas of the 

Metropolitan Water Reclamation District of Greater Chicago 

(MWRD) and neighboring counties is presented to illustrate how communities in a rapidly developing region adopt 

detention basin and release rate ordinances. The MWRD area 

covers Cook County and parts of DuPage and Will Counties. More detailed information can be found in the reports 

prepared by Dreher and others (1989) and the Northeastern 

Illinois Planning Commission (NIPC) (1985). 

In 1972, MWRD began to require that stormwater detention be provided for new development (Dreher and others, 

1989). This detention ordinance called for all residential developments more than 10 acres and all commercial and industrial 

developments more than 5 acres to provide stormwater detention to limit postdevelopment 100-year event runoff peaks to 

predevelopment peak flows. The allowable postdevelopment 

release rate for the 100-year storm is equivalent to the predevelopment 3-year storm runoff rate based on the modified 

rational formula (Chow and others, 1988) with a maximum 

runoff coefficient “C” of 0.15. Given the rainfall statistics and 

physical characteristics of typical watersheds in northeastern 

Illinois, a typical maximum release rate is about 0.3 ft3/s-acre, 

and it may range from 0.2 ft3/s-acre to 0.5 ft3/s-acre. Smaller 

release rates are used as watershed size increases. This 

MWRD detention ordinance has been the basis of other detention policies in northeastern Illinois (Dreher and others, 1989). 

The NIPC (1985) examined 38 local stormwater detention requirements outside Cook County. Several ordinances 

eliminated the 10-acre minimum residential development size 

for required stormwater detention if the site impervious area 

exceeded 50 percent, and some ordinances required detention 

for all new development regardless of development size or 

amount of impervious area. The choice of the majority of the 

municipalities was to design the postdevelopment release rate 

for control of the 100-year event. In practice, the most widely 

used method of determining allowable detention release rate 

was the MWRD method using either a 3-year or a 2-year 

event. About one-third of the communities specified a fixed 

release rate; the rates were almost evenly divided between 0.1 

and 0.12 ft3/s-acre. 
Detention Modeling 3

The effectiveness of existing detention policies in northeastern Illinois was evaluated by NIPC (Dreher and others, 

1989). As a result, release rates for the 2-year and 100-year 

storm events were recommended for use in northeastern Illinois in the absence of a comprehensive stormwater management plan for a particular watershed. Price and Dreher (1991) 

found that the design storm methods appear to either over- or 

underpredict detention requirements based on different landuse assumptions. Because of the difficulty in using the design 

storm methods, the unit area-detention volume requirements 

were developed based on over 40 years of continuous hydrologic simulation (Price and Dreher, 1991; Price, 1997) as 

an alternative to the design storm approach for determining 

detention requirement and release rate. The resulting unit areadetention volumes requirements have been used in DuPage 

and Lake Counties to develop stormwater ordinances (Price, 

1997). 

Release Rates in Continuous Hydrologic 

Simulation

Donigian and others (1997) used HSPF to investigate 

improvements in flood control and water quality by including various detention basin design scenarios in a study of 

Calabazas Creek, California. A 50-year continuous simulation was performed at an hour time step, and the routing and 

release of flow through detention basins were described by a 

set of depth-surface area-volume-discharge relations called 

“Ftables” in the HSPF model. The surface runoff was routed 

from impervious areas to detention basins, and the amount of 

flow released from a detention basin to a downstream stream 

channel was determined from the detention Ftable. Typical 

detention basin design information was obtained from the 

Santa Clara Valley Water District to develop an appropriate 

Ftable, and the stage, volume, surface area, and discharge relation were calculated accordingly. The first Ftable was designed 

for an 800-acre drainage area. Ftables for other drainage-area 

sizes were developed by adjusting discharge, volume, and 

surface-area values proportionally to the drainage area. For the 

Calabazas Creek watershed, the results showed that none of 

the detention basin scenarios had a substantial impact on mean 

annual flow volumes, but daily peak discharge decreased for 

events of 10-year recurrence interval or less. However, flow 

rates for less frequent (more extreme) floods changed little, 

and some locations showed small increases in peak-flow rates 

in the simulation. 

Detention Modeling

In an HSPF schematic, the inflow to a river reach 

(RCHRES) may consist of the flow entering the reach from an 

upstream reach, or flow from contributing pervious land and 

impervious land segments, or both. To describe outflows from 

a reach, an Ftable is needed that describes the relations among 

the outflow rates and channel-reach geometry including 

depth, surface area, and volume. Donigian and others (1997) 

suggested that the Ftable concept can be applied to outflow 

from a detention basin by:

1. Decreasing the outflow rates associated with the 

given storage volumes to simulate a flow-control 

structure across the channel, or

2. Increasing the channel-storage volumes associated 

with the given discharges to simulate creation of 

one or more storage pools adjacent to the channel or 

upstream from the discharge point. 

Modifications to the outflow discharge and storage relations could be achieved by using either hypothetical or computed design based on field or proposed basin dimensions or 

a combination of both. Proper determination of these outflow 

discharge and storage relations is essential for sizing the detention basin and, therefore, also determines the how effective the 

detention basin is for stormwater management.

Detention Basin Volume Estimation

In a study for DuPage County, Price (1997) devised a 

method that uses the HSPF continuous simulation approach 

to estimate the sizing requirement for a 100-year detention 

basin with an outlet release rate of 0.1 ft3/s-acre from a linear 

slot outflow structure (fig. 1). The design chart allows users to 

determine detention volumes based on the amount of hydraulically connected impervious area (expressed as a percentage) in 

the watershed. Price (1997) found that the required detentionbasin storage ranged from 0.245 to 0.554 acre-ft/acre for 

contributing watersheds with impervious areas ranging from 0 

to 100 percent. Price (1997) first assumed a group of 100-acre 

hypothetical watersheds with impervious land areas ranging 

from 0 to 100 percent. A trial-and-error approach was developed with the following steps:

1. Determine a set of assumed (initial) detention 

volume-discharge relations, which will be the data 

for constructing Ftables, for the linear slot outlet 

structure, then 

2. Run the HSPF model with the Ftable implemented, 

and simulate hourly flow at the outlet using the longterm precipitation record from water years1

 (WY) 

1949 to 1993 recorded at Wheaton, Ill., as the input. 

3. Generate the annual maximum time series (AMS) 

from the simulated outflow, and determine flood 

frequencies from the AMS using the Log Pearson 

Type III distribution with procedures outlined in 

Bulletin 17B (Interagency Advisory Committee on 

Water Data, 1982).

4. Stop the process if the 100-year discharge is equal to 

0.1 ft3/s-acre of the drainage basin; if not, then a new 

volume-discharge relation is chosen for the process 

until the desired release rate is achieved.

1

 A water year (WY) is the 12-month period from October 1 through 

September 30 and is designated by the calendar year in which it ends. For 

example, WY 2007 is from October 1, 2006, through September 30, 2007.
4 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

In the current study, an orifice-weir outlet structure was 

modeled. Water is released from a detention basin first through 

an orifice and then over a weir if the storm exceeds the design 

storage of the detention basin. The orifice outlet is the structure specified by Kane County (Kane County Stormwater 

Management, 2005). The release rate discharge and detention 

storage volume relations for the linear slot and orifice outlet 

structures were computed for the release rate of 0.1 ft3/s-acre 

and are compared in figure 1. 

of 1 ft3/s-acre for runoff exceeding the 100‐year 

magnitude. This set of relations was developed with 

a spreadsheet modified from one obtained from 

CBBEL (Darren Olsen, Christopher B. Burke, Ltd., 

written commun., 2005) for detention basins.

2. Incorporate the Ftable determined in step 1 into the 

HSPF model, and simulate hourly flow at the outlet 

using precipitation data from Argonne National 

Laboratory, Argonne, Ill., for WY 1949 to WY 2003. 

3. Generate an AMS from this simulated flow time 

series, and analyze flood frequency with the 

PEAKFQ program (Flynn and others, 2006) to 

estimate flood frequencies with the Bulletin 17B 

method. Note that the 1996 annual maximum was 

removed from the AMS because it is considered an 

outlier for the purpose of determining release rate. 

The 1996 annual maximum discharge measured 

at Yorkville, Ill., was larger than a 500-year peak 

discharge. Inclusion of this data point in the release 

rate analysis would have biased the flood frequencies 

computed for other recurrence intervals. 

4. Stop the process if the 100-year discharge is equal to 

the desired release rate; if not, then a new diameter 

(and therefore detention basin volume) is tested until 

the desired release rate is achieved.

The procedure presented above presents an estimate of 

the total detention basin volume needed in each subbasin. For 

example, the resulting detention basin storage volume for subbasins in the Blackberry Creek watershed ranged in size from 

approximately 3 to 810 acre-ft. The detention basins larger 

than 400 acre-ft were judged to be unlikely to be constructed 

in residential developments and were split into detention 

basins of 350 acre-ft or less for modeling purposes. 

Multiple Release Rates

The required 100-year detention volumes (in acre-ft/acre) 

for an orifice-outlet structure for different amounts of impervious area and for the multiple release rates of 0.08, 0.10, 

and 0.12 ft3/s-acre are shown in figure 2. This diagram was 

developed to aid watershed planning for new development 

areas. When an orifice-outlet structure is used, approximately 

0.47–0.52 acre-ft of storage per acre of impervious land is 

required to achieve a release rate of 0.10 ft3/s-acre for the 

100-year storm. In addition, 0.495–0.565 acre-ft of storage per 

acre of impervious land was required to achieve a release rate 

of 0.08 ft3/s-acre, and 0.43–0.475 acre-ft of storage per acre 

of impervious land was required to achieve a release rate of 

0.12 ft3/s-acre. 

Figure 1. The differences in storage volume required by a linear 

slot volume-discharge relation and an orifice-controlled storage 

volume-discharge relation. A release rate of 0.1 cubic feet per 

second per acre was used in the analysis. 

0

2

4

6

8

10

12

0 10 20 30 40 50 60

STORAGE VOLUME, IN ACRE-FEET

DISCHARGE, IN CUBIC FEET PER SECOND

Orifice

Linear

The volumetric requirement for the orifice structure is 

usually smaller than that required by the linear slot outlet 

except at a very small release discharge. The intent of the 

linear slot structure used by Price (1997) was to derive a simplified relation. Use of an orifice-outlet structure gives a more 

realistic estimate of detention basin volume and, therefore, 

more accurate analysis in the Blackberry Creek watershed. 

The Price (1997) method is modified in this study to size 

detention basins and outlet structures as outlined below.

1. Determine an initial set of depth-surface area-storage 

volume-discharge relations (Ftables) with a trial orifice diameter and weir elevation. For this study, the 

detention basin has a general trapezoidal shape, flat 

bottom, and side slope of 4 to 1. The orifice is placed 

at the bottom of the outlet structure and the diameter 

is determined in the subsequent trial-and-error exercise until the desired release rate is met at the outlet. 

The elevation of the weir is designed to detain runoff 

magnitudes up to the 100-year recurrence interval 

before water overtops the weir, and the effective 

weir width is designed to release discharge at a rate 
Blackberry Creek Detention Modeling Case Study 5

Blackberry Creek Detention Modeling 

Case Study

The Blackberry Creek watershed is a 68.1 mi2 (Murphy 

and others, 2007) watershed approximately 40 mi west of metropolitan Chicago in Kane and Kendall Counties, Ill. (fig. 3). 

Land use in the watershed is primarily agricultural; however, 

in the past few decades, urban areas have been developed 

throughout the watershed. In 2005, the USGS–Illinois Water 

Science Center, in cooperation with the KCDEM, developed, 

calibrated, and verified an HSPF hydrologic model to investigate flood-hazards in the watershed (Soong and others, 2005). 

This hydrologic model, based on 1996 land use, was modified 

in this study to incorporate projected 2020 land-use changes 

(Price, 2003) and detention basins simulated with Ftables 

incorporating the release rates as previously described. 

Figure 3. Location of the Blackberry Creek watershed in Kane County, Illinois. 

Figure 2. Detention storage volume required per acre to achieve 

a 0.08, 0.10, or 0.12 cubic feet per second per acre detention 

release rate for different amounts of impervious area. 

IMPERVIOUS AREA, ACRES

0 50 100 150 200 250 300 350

DETENTION VOLUME, RATIO IN ACRE FEET PER ACRE 0.420

0.440

0.460

0.480

0.500

0.520

0.540

0.560

0.580

Release Rate 0.08

Release Rate 0.10

Release Rate 0.12

Batavia

Montgomery

(05551675)

US 30 / Rt 47

Rt 47

I-88

Main St

US 30

Rt 38

Bliss Rd

Jericho Rd

Randall Rd

Rt 56

Union Pacific RR

Galena Blvd

Oak St

Hankes Rd

Burlington RRPouley Rd

Green Rd

US 30

Prairie St

88°30' 88°25' 88°20'

41°45'

41°50'

41°55'

Base from U.S. Geological Survey

,

and Illinois Department of Natural Resources 1:24,000

Digital Data Illinois State Plane East Coordinate System (Feet), NAD83 Datum

Kendall Co.

Kane Co.

EXPLANATION

CITY

STREAM

INTERSTATE HIGHWAY

U.S. HIGHWAY

STATE HIGHWAY

ROAD

RAILROAD

COUNTY BOUNDARY

STREAMFLOW-GAGING

STATION AND IDENTIFIER

WATERSHED BOUNDARY

Montgomery

(05551675)

U

Creek

Bl er ackb ry

Aurora

North

Aurora

Jericho Lake

0 1.25 2.5 5 KILOMETERS

0 1.25 2.5 5 MILES

Elburn Run

.

Seavey Roa u d R n

Lake Run

Prestbur . y Br

East Run

Aurora

Chain-of-Lakes

Route 38

Branch

ILLINOIS

Blackberry Creek

Watershed

Sugar

Grove

Elburn

U+
6 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Data 

Meteorological data, geographic information system data 

layers for the analysis, subwatershed boundaries, and channel 

geometry are described in the 2005 flood-hazard study (Soong 

and others, 2005). However, the current study extended 

the meteorological data and the simulation period through 

WY 2003, whereas the 2005 study used the period WY 1950 

to WY 1999. In addition, the Kane County projected 2020 

land-use data (Price, 2003) were used as the basis for sizing 

the detention basins in this study. Changes in flood frequencies 

resulting from these additional four years of meteorological 

data can be observed in the two curves in figure 4. The flood 

frequency streamflow values from the WY 1950 to WY 2003 

simulation period are slightly lower for the smaller exceedance probabilities. The slight changes in flood frequencies 

are expected because estimation of recurrence intervals is 

improved with longer records. 

After these land-use categories were incorporated in the 

watershed geographic information system (GIS) layer, the surface area for each land use in each subbasin (fig. 6) was calculated in acres and updated in the 1996 land-use HSPF model 

to create the 2020 land-use HSPF model. The key differences 

between the 1996 and 2020 land-use models were the increase 

in impervious land area and the corresponding decrease in 

pervious land area. The total drainage areas, percentage of 

impervious area in 1996, and percentage of increased impervious area by 2020 for each tributary subbasin are shown in 

table 2 and for the Blackberry Creek main stem subbasins in 

table 3. Note that the largest amounts of projected development are planned for the tributary subwatersheds of Elburn 

Run, Prestbury Branch, East Run, and Aurora Chain-of-Lakes, 

and along the main stem in subbasin 236. 

Methods

The land areas that were reclassified from pervious areas 

in the 1996 land use to impervious area in the 2020 land use 

were considered new development that would require detention. Detention basins with the three different release rates of 

0.08, 0.10, and 0.12 ft3/s-acre were created in all Kane County 

subbasins of the Blackberry Creek watershed. A version of the 

model that incorporated the 2020 land use without detention 

basins was used as the “worst-case scenario” for comparison 

with the detention scenario model versions.

Figure 4. Comparison of flood frequency curves estimated at 

the U.S. Geological Survey streamflow-gaging station at Yorkville, 

Illinois, from Argonne National Laboratory precipitation data from 

1950–99 and 1950–2003. 

The projected 2020 land-use conditions (fig. 5) were 

based on the 2020 land-use map developed by Price (2003). 

The Price (2003) map used the Kane County data (Karen 

Kosky, Kane County Department of Environment and Building Management, written commun., October 2002) and 

incorporated urban development in the Blackberry Creek 

watershed. It also incorporated the municipal planning maps 

of Aurora, North Aurora, Batavia, Elburn, Montgomery, and 

Sugar Grove. For consistency of the analysis, the 2020 landuse categories were associated with the 1996 land-use categories used in the 2005 Blackberry Creek watershed flood-hazard 

study as described in table 1. The 2020 land-use category of 

“existing open space” was overwritten with the 1996 land-use 

category.

Table 1. Land-use categories from the 2005 Blackberry Creek 

flood-hazard study and associated 2020 land-use categories. 

[1996 land-use categories from Soong and others (2005)] 

1996 land-use category 2020 land-use category

Cropland Agriculture

Grassland Agriculture resource buffer, 

additional open space, proposed 

open space, existing rural 

grassland, urban grassland

High-density urban Crossroad commercial, urban 

residential, commercial, 

office/research, industrial, light 

industrial, warehouse, urbanized 

municipality, rural municipality

Medium-density urban Rural residential, agricultural 

business, institutional

Low-density urban Countryside/estate residential

Transportation Transportation

Water bodies Water

Wetland Wetland

Barren land Barren land

EXCEEDANCE PROBABILITY, IN PERCENT

DISCHARGE, IN CUBIC FEET PER SECOND

90.0 70.0 50.0 30.0 10.0 1.0 0.1

400

1,000

5,000

100-year flood

2-year flood

LU1996 (1950-1999)

LU1996 (1950-2003)
Figure 5. 1996 and projected 2020 land uses for the Kane County portion of the Blackberry Creek watershed. 

Land cover base from Luman and others, 1996. Land cover base from Price

88°30'

88°25'

41°45' 41°45'

41°50'

41°55'

88°30'

88°25'

88°20'

41°50'

41°55'

Sugar

Grove

Elburn

Rt 47

I-88

Rt 38

US 30 Rt 56

Kendall Co.

Kane Co.

Aurora

North

Aurora

Sugar

Grove

Elburn

Batavia

Rt 47

I-88

US 30

Rt 38

US 30 Rt 56

Kendall Co.

Kane Co.

B

l

e

r

a

c

k

b

ry

C

reek

Base for maps from U.S. Geological Survey

,

and Illinois Department of

Natural Resources 1:24,000 Digital Data Illinois State Plane East

Coordinate System (Feet), NAD83 Datum

EXPLANATION

LAND COVER

Barren and exposed

WATERSHED BOUNDARY

High density urban

Medium density urban

Low density urban

Transportation

Cropland

Grassland

Wooded and forested land

Wetland

Open water

0 5 KILOMETERS

0 5 MILES

1996 Land Cover Pr

La

Montgomery 
8 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Figure 6. Subbasins and naming system used in the Hydrological Simulation Program–FORTRAN model 

for the Blackberry Creek watershed in Kane County, Illinois. 

Jericho Lake

Route 38 Branch Tributary (10)

Seavey Road Run

(30-33)

Tributary

Lake Run Tributary

(50-57)

East Run

Tributary

(60-64)

Aurora

Chain-of-Lakes

Tributary

(70-79)

Prestbury Branch

Tributary

(40-41)

Main Stem of

Blackberry Creek

(208-276)

Elburn Run

(20-22)

Tributary

53

52

51

276

33

41

31

30

32

236

223

50

62

240

213

226

220

210

230

21

64

60

73

74

75

76

77

78 79

216

22

63

20

260

265

218

208

250

10

54

70

57

233

56

55

88°30' 88°25' 88°20'

41°40'

41°45'

41°50'

41°55'

0 1.25 2.5 5 KILOMETERS

0 1.25 2.5 5 MILES

Blackberry

Creek

Base from U.S. Geological Survey

,

and Illinois Department of Natural

Resources 1:24,000 Digital Data Illinois State Plane East Coordinate

System (Feet), NAD83 Datum

40 61

U+

270

72

71

U

EXPLANATION

SUBBASIN AND IDENTIFIER

STREAMFLOW-GAGING STATION

230

Kendall Co.

Kane Co.

Montgomery

(05551675)
Blackberry Creek Detention Modeling Case Study 9

Table 2. Drainage area, impervious area determined from the 1996 land-use map, and projected 

additional impervious area by 2020 for tributary subbasins of the Blackberry Creek watershed in 

Kane County, Illinois. 

[1996 land use from Luman and others, 1996; projected additional impervious area by 2020 from Price, 2003, and 

Karen Kosky, Kane County Department of Environmental and Building Management, written commun., October 2002]

Subbasin number 

(figure 6)

Subbasin drainage 

area (acres)

Impervious area in 1996 

(percent)

Projected additional 

impervious area 

by 2020 (percent)

Route 38 Branch

10 367.4 1.06 9.99

Elburn Run

22 522.2 7.75 50.49

21 627.1 2.07 34.15

20 502.1 2.71 16.8

Seavey Road Run

33 1,204.20 1.53 2.43

32 1,044.30 .51 0

31 1,124.60 1.3 .48

30 1,124.80 1.52 1.94

Prestbury Branch

41 1,132.80 4.01 44.49

40 235.3 7.38 46.95

Lake Run

57 1,104.70 1.2 0

56 391 1.02 3.77

55 383.7 2.99 2.48

54 247.1 .63 0

53 1,915.00 2.46 9.08

52 1,902.10 1.4 2.39

51 1,741.60 1.13 2.17

50 903.4 2.97 30.03

East Run

64 613.2 4.54 38.82

63 518 7.93 56.8

62 879.4 3.25 66.46

61 312.6 2.6 43.81

60 557.2 5.61 25.24

Aurora Chain-of-Lakes

79 405.6 15.09 52.45

78 239.5 17.95 48.09

77 504.9 21.54 60.15

76 325.6 41.16 42.33

75 253.4 25.18 55.54

74 87.8 9.49 57.89

73 343.5 21.99 69.24

72 136.8 13.96 78.26

71 84.7 3.11 41.57

70 223.4 5.4 42.53
10 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Table 3. Drainage area, impervious area determined from the 

1996 land-use map, and projected additional impervious area by 

2020 along the main stem of the Blackberry Creek watershed in 

Kane County, Illinois. 

[1996 land use from Luman and others, 1996; projected additional 

impervious area by 2020 from Price, 2003, and Karen Kosky, Kane County 

Department of Environmental and Building Management, written commun., 

October 2002]

Subbasin 

number

Subbasin 

drainage 

area (acres)

Impervious 

area in 1996 

(percent)

Projected additional 

impervious area 

by 2020 (percent)

208 632.3 0.39 0.49

210 980.4 2.86 9.3

213 1,080.00 1.06 35.01

216 792.7 1.86 5.78

218 634.2 1.67 8.14

220 1,003.30 2.16 9.98

223 1,415.80 2.46 11.41

226 1,033.60 3.28 2.68

230 947.8 2.2 6.6

233 1,278.70 4.79 12.27

236 1,471.00 4.65 55.13

240 1,269.30 3.79 15.09

250 556.4 2.22 11.21

260 663.9 2.55 13.41

265 635.2 .87 4.61

270 428.5 3.66 13.54

The surface runoff from new impervious areas was routed 

to detention basins. The routing and release of flow through 

detention basins was described by using Ftables in the HSPF 

model as previously discussed. The amount of flow released 

from a detention basin to the channel was determined from the 

corresponding detention Ftable. The flow released from the 

detention basin plus the flow from the pervious and impervious surface areas were routed using the channel routing Ftable 

developed in the 1996 land-use HSPF model. The annual 

maximum series was compiled from the simulated flow time 

series. Design recurrence intervals flows were determined 

through statistical analysis of the annual maximum series. 

The areas selected for analysis, listed from upstream to 

downstream along Blackberry Creek in Kane County, include: 

the confluences of Blackberry Creek with Route 38 Branch 

tributary, Elburn Run tributary, Seavey Road Run tributary, 

Prestbury Branch tributary, Lake Run tributary, East Run 

tributary, Aurora Chain-of-Lakes tributary; the stream crossing 

at Route 47 downstream from Elburn Run; the outlets of subbasins 230, 236, 240, 250, 260, 265; and at the Kane-Kendall 

county line (fig. 6). Flood-peak magnitudes for 2-, 10-, 100-, 

and 500-year recurrence intervals from selected storm events 

were analyzed. 

Simulation Results

Simulated flood frequencies and flood hydrographs at the 

outlet of each tributary (table 4) and selected locations along 

the main stem of Blackberry Creek in Kane County (table 5) 

are presented in this section. For each selected subbasin, 

five scenarios were simulated: the 1996 and 2020 land uses 

and the 2020 land uses with the three detention basin release 

rates of 0.08, 0.10, and 0.12 ft3/s-acre (figs. 7–21). The 1996 

and 2020 land-use scenarios are plotted for the full range of 

recurrence intervals, whereas the detention basin scenarios are 

only plotted for the 2- through 100-year recurrence intervals. 

The results of the simulations for the five scenarios for one 

subbasin are grouped in a single illustration for a comparative 

evaluation. A summary table of estimated flood quantiles for 

the 2-, 10- , 50-, and 100-year recurrence intervals is presented 

in the appendix. Among the four storm runoff events selected, 

the July 1996 event is larger than a 100-year event, and the 

May 1999 event is approximately a 2-year event, according 

to the flood frequencies based on the 1950–2003 discharge 

record measured at the USGS streamflow-gaging station at 

Yorkville (station number 05551700). 

Analysis of the flood frequencies and storm-runoff 

hydrographs for the five scenarios at different locations in the 

watershed (figs. 7–21) reveals the effectiveness of detention 

basins with different release rates and the effect of detention 

basins on downstream reaches. Some general observations 

from these plots include: 

1. an increase in impervious area results in an increase 

in the storm-runoff magnitudes; 

2. the addition of detention basins reduces flood peaks 

but also prolongs the release of stored flood water, 

thus producing a flood hydrograph that shows a longer recession time and larger discharge magnitude; 

3. although the release rate is designed to reduce the 

100-year peak flow, reduction of the 2-year peak flow 

is also achieved for a smaller proportion of the peak; 

and 

4. the shape of the hydrographs generated by different 

detention basin release rates are similar but the magnitudes and duration of recessional flows tend to vary 

among storm events and locations.

The hydrographs from the July 1996 event (larger than 

a 100-year event) and the May 1999 event (approximately 

a 2-year event) can be used to examine the magnitude of 

flood-peak discharge increases with the 2020 land uses and no 

detention basins (figs. 7–21). The hydrographs demonstrate 

that projected new development occurring between 1996 and 

2020 will increase flood peaks for both large and small storms. 
Blackberry Creek Detention Modeling Case Study 11

Table 4. Tributaries in the Blackberry Creek watershed, Kane 

County, Illinois, with numerical codes for the most downstream 

subbasin, and figure numbers where the simulation results are 

shown. 

Tributary name Subbasin 

number

Figure 

number

Route 38 Branch 10 7

Elburn Run 20 8

Seavey Road Run 30 9

Prestbury Branch 40 10

Lake Run 50 11

East Run 60 12

Aurora Chain-of-Lakes 70 13

Table 5. Detention basin release-rate evaluation locations 

along the main stem of Blackberry Creek in Kane County, Illinois, 

numerical codes for the subbasin upstream from each location, 

and figure numbers where the simulation results are shown. 

Location name Subbasin 

number

Figure 

number

Stream crossing Route 47, downstream 

from the junction with Elburn Run

220 14

Stream crossing Route 47 downstream from 

the junction with Seavey Road Run

230 15

Stream crossing Village of Sugar Grove 236 16

Near Route 56 stream crossing upstream 

from the junction with Lake Run

240 17

Upstream from the junction with East Run 250 18

Downstream from the junction with 

East Run

260 19

Upstream from the junction with Aurora 

Chain-of-Lakes

265 20

At Kane and Kendall County line 270 21

The storm hydrographs also can show the effect of the 

land-use changes on the runoff-generation characteristics—

storms that did not produce major runoff events with the 1996 

land uses would produce runoff with the 2020 land uses—the 

June 1994 event, for example. Therefore, subbasins projected 

to have rapid development between 1996 and 2020 will have 

more frequent small flood runoffs than other subbasins even if 

climatic conditions are the same. Changes in the occurrences 

and magnitudes of small floods may contribute to the increase 

in flood frequencies at short recurrence intervals, such as a 

2-year storm (Q2). Examples of this increase can be seen in 

flood frequency curves for the 1996 and 2020 land uses such 

as those in figures 7, 8, 16, and 17.

On the watershed scale, implementing detention basins 

with a release rate of 0.1 ft3/s-acre controls the Q100 from the 

2020 land-uses level to close to the 1996 land-uses level at 

the Kane-Kendall county line (fig. 21). At the county line, 

implementation of detention basins reduced simulated flood 

quantiles of recurrence intervals shorter than 100 years from 

the 2020 land-use levels even though the detention basin were 

designed to control the Q100 peak flows. However, the effectiveness of detention-controlled Q100’s for individual subbasins 

was shown to vary. This variation in effectiveness is due to the 

variation in the amount of urban development in each subbasin 

between the 1996 and 2020 land-use data. The detention-controlled Q100’s are lower than the 1996 land-use levels at Route 

38 Branch (subbasin 10), Elburn Run (20), Prestbury Branch 

(40), and Lake Run (50) tributaries,at the stream crossing 

Route 47 downstream from junction with Elburn Run (220), 

the stream crossing Route 47 downstream from junction with 

Seavey Road Run (230), and Village of Sugar Grove (236) 

on the main stem. The detention-controlled Q100’s are higher 

than the 1996 land-use levels at East Run (60) and Aurora 

Chain-of-Lakes (70) tributaries. The 0.1 ft3/s-acre release rate 

could not reduce the Q100’s to the 1996 land-use levels at the 

outlet of East Run and Aurora Chain-of-Lakes tributaries. A 

smaller release rate, such as 0.08 ft3/s-acre, would be required 

to achieve comparable flow reduction.

Existing channel-routing characteristics are an additional 

consideration in evaluating the effect of detention basins at 

downstream locations. The Prestbury Branch, East Run, and 

Aurora Chain-of-Lakes tributaries have higher projected urban 

development by 2020 (table 2) and have existing engineered 

channel modifications, such as flow-through lakes, incorporated in the 1996 land-use HSPF model. Although an in-depth 

evaluation of the effect of the channel modifications on the 

downstream flow conditions is beyond the scope of this 

study, appreciable peak attenuation and runoff smoothing can 

be observed in Prestbury Branch tributary (fig. 10). These 

hydrograph characteristics result from the tributary’s comparatively large storage capacity in two large lakes and from 

mild channel slopes. This channel storage allows the Q100’s to 

be controlled to the 1996 level for this subbasin despite the 

projected urban development. 

Subbasins along the main stem of the Blackberry Creek 

in the middle part of the watershed have minimal impervious 

area (table 3) and are primarily agriculture and pasture land 

uses in the 1996 land-use data. Simulated detention-controlled 

Q100’s lower than the 1996 levels could indicate an overdesigned system from using an overly strict detention basin 

release rate. Over- and under-design of stormwater facilities 

such as detention basins can cause undesirable impacts to the 

aquatic habitat or channel stabilization, as well as flooding. 
12 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

The changes in flood quantiles due to release rate 

controlled detention throughout the watershed are inconsistent. To illustrate this inconsistency, ratios of QT (T denotes 

a specific recurrence interval) to drainage area (DA) were 

computed for subbasins in the Blackberry Creek watershed. 

The QT/DA ratios with QT’s simulated by the 1996 land-use 

HSPF model were compared to those QT’s simulated with the 

2020 land uses with 0.1 ft3/s-acre release rate detention basins 

HSPF model (table 6). Ratios for two recurrence intervals, 

Q2 and Q100, were analyzed. In small headwater watersheds, 

runoff from rainfall begins more quickly and is less attenuated 

because of small available storage. Therefore, Q100/DAratios 

of small watersheds are higher (higher than 0.1 ft3/s-acre) than 

larger watersheds. Requiring a low release rate for a watershed 

with higher initial urban development may result in a lower 

postdevelopment Q100, such as in subbasin 240. 

Table 6. Ratios of peak flow and drainage area for pre- and postdevelopment scenarios at selected locations in the Blackberry Creek 

watershed, Kane County, Illinois. 

[ft3/s-acre, cubic foot per second per acre; Q2 and Q100 are the 2-year and 100-year flood quantiles, respectively; 0.1 RR, 0.1 ft3/s-acre release rate] 

Subbasin 

number 

(figure 6)

Total 

drainage area 

(acres)

100-year flood/drainage area

(ft3/s-acre)

2-year flood/drainage area

(ft3/s-acre)

Q100 based on 

1996 land uses

Q100 based on 

2020 land uses 

and 0.1 RR

Q2 based on 

1996 land uses

Q2 based on 

2020 land uses 

and 0.1 RR

10 367 0.29 0.27 0.07 0.07

20 1,651 .54 .42 .09 .08

30 4,498 .16 .16 .03 .03

40 1,368 .05 .05 .01 .02

50 8,588 .12 .11 .03 .03

60 2,880 .06 .08 .01 .02

70 2,605 .03 .07 .01 .01

220 7,142 .19 .16 .04 .03

230 15,037 .13 .12 .03 .03

236 17,787 .11 .1 .03 .03

240 20,424 .1 .1 .02 .03

250 29,569 .09 .09 .02 .02

260 33,113 .09 .09 .02 .02

265 33,748 .08 .08 .02 .02

270 36,782 .07 .08 .01 .02
Blackberry Creek Detention Modeling Case Study 13

Figure 7. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates downstream from Route 38 Branch tributary to Blackberry Creek, Kane County, 

Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

06/23/94

07/17/96

06/25/94

07/19/96

06/27/94

07/21/96

0

4

8

12

16

01/12/95

05/21/99

01/14/95

05/22/99

01/16/95

05/23/99 05/24/99

0

0

2

4

6

8

10

12

5

10

15

20

25

30

20

0

40

60

80

100

120

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

1

10

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
14 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Figure 8. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates downstream from Elburn Run tributary to Blackberry Creek, Kane County, Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/17/96 07/18/96 07/19/96 07/20/96 05/21/99 05/22/99 05/23/99 05/24/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

1

10

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/25/94 06/27/94

0

0

50

100

150

200

01/12/95 01/14/95 01/16/95

0

0

20

40

60

80

100

120

200

400

600

800

1,000

1,200

1,400

50

100

150

200

250

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
Blackberry Creek Detention Modeling Case Study 15

Figure 9. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates downstream from Seavey Road Run tributary to Blackberry Creek, Kane County, 

Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/17/96 07/19/96 07/21/96 05/21/99 05/23/99 05/25/99

0

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

1

10

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/25/94 06/27/94 01/12/95 01/15/95 01/18/95

0

5

10

15

20

200

400

600

800

1,000

1,200

0

0

10

20

30

40

50

60

70

20

40

60

80

100

120

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
16 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Figure 10. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates downstream from Prestbury Branch tributary to Blackberry Creek, Kane County, 

Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

06/23/94

07/17/96

06/25/94

07/19/96

06/27/94

07/21/96 05/21/99 05/24/99 05/27/99

0

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

1

10

100

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

0

5

10

15

01/13/95 01/16/95 01/19/95

0

0

5

10

15

20

100

200

300

400

500

600

700

10

20

30

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
Blackberry Creek Detention Modeling Case Study 17

Figure 11. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates downstream from Lake Run tributary to Blackberry Creek, Kane County, Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

06/23/94

07/17/96

06/25/94

07/20/96

06/27/94

07/23/96

01/12/95

05/21/99

01/15/95 01/18/95

05/24/99 05/27/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

1

10

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

0

0

20

40

60

80

100

0

0

20

40

60

80

100

120

500

1,000

1,500

2,000

50

100

150

200

250

2-year

10-year

100-year

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
18 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Figure 12. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates downstream from East Run tributary to Blackberry Creek, Kane County, Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/17/96 07/20/96 07/23/96 05/23/99 05/26/99 05/29/99 06/01/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

1

10

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/26/94 06/29/94

0

0

10

20

30

40

50

60

70

01/12/95 01/15/95 01/18/95

0

0

10

20

30

40

50

60

70

400

200

600

800

1,000

20

10

30

40

50

60

70

80

90

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
Blackberry Creek Detention Modeling Case Study 19

Figure 13. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses 

and selected detention basin release rates downstream from Aurora Chain-of-Lakes tributary to Blackberry Creek, Kane 

County, Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/17/96 07/20/96 07/23/96 05/23/99 05/26/99 05/29/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

1

10

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/26/94 06/29/94

0

0

5

10

15

20

25

30

01/12/95 01/15/95 01/18/95

0

5

5

10

15

20

25

30

200

400

600

800

1,000

10

15

20

25

30

35

40

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
20 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Figure 14. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates on Blackberry Creek at Route 47 downstream from the junction with Elburn Run 

(subbasin 220), Kane County, Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/17/96 07/20/96 07/23/96 05/21/99 05/24/99 05/27/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

10

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/25/94 06/27/94

0

0

50

100

150

200

250

500

01/12/95 01/15/95 01/18/95

0

0

50

50

100

150

200

250

1,000

1,500

2,000

2,500

3,000

100

150

200

250

300

350

400

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
Blackberry Creek Detention Modeling Case Study 21

Figure 15. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates on Blackberry Creek at Route 47 downstream from the junction with Seavey Road 

Run (subbasin 230), Kane County, Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/17/96 07/20/96 07/23/96 05/21/99 05/24/99 05/27/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/25/94 06/27/94

0

0

50

100

150

200

250

01/12/95 01/15/95 01/18/95

0

0

50

100

150

200

250

300

350

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

100

200

300

400

500

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
22 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Figure 16. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates on Blackberry Creek near the Village of Sugar Grove (subbasin 236), Kane County, 

Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/19/96 07/22/96 07/25/96 05/21/99 05/24/99 05/27/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/25/94 06/27/94

0

0

50

100

150

200

250

300

350

01/12/95 01/15/95 01/18/95

0

0

50

100

150

200

250

300

350

400

1,000

2,000

3,000

4,000

5,000

100

200

300

400

500

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
Blackberry Creek Detention Modeling Case Study 23

Figure 17. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates on Blackberry Creek upstream from the junction with Lake Run (subbasin 240), 

Kane County, Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/19/96 07/22/96 07/25/96 05/21/99 05/24/99 05/27/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/25/94 06/27/94

0

0

50

100

150

200

250

300

350

400

01/12/95 01/15/95 01/18/95

0

0

50

100

150

200

250

300

350

400

450

1,000

2,000

3,000

4,000

5,000

100

200

300

400

500

600

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
24 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Figure 18. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates on Blackberry Creek upstream from the junction with East Run (subbasin 250), 

Kane County, Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/18/96 07/20/96 07/22/96 07/24/96 07/26/96 05/21/99 05/23/99 05/25/99 05/27/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/25/94 06/27/94

0

0

50

100

150

200

250

300

350

01/12/95 01/14/95 01/16/95 01/18/95

0

0

100

200

300

400

500

1,000

2,000

3,000

4,000

5,000

6,000

7,000

100

200

300

400

500

600

700

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
Blackberry Creek Detention Modeling Case Study 25

Figure 19. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates on Blackberry Creek downstream from the junction with East Run (subbasin 260), 

Kane County, Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/19/96 07/22/96 07/25/96 05/21/99 05/24/99 05/27/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

100

1,000

10,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/25/94 06/27/94

0

0

50

100

150

200

250

300

350

400

01/12/95 01/15/95 01/18/95

0

0

100

200

300

400

500

600

1,000

2,000

3,000

4,000

5,000

6,000

7,000

100

200

300

400

500

600

700

800

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
26 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Figure 20. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses 

and selected detention basin release rates on Blackberry Creek upstream from the junction with Aurora Chain-of-Lakes 

(subbasin 265), Kane County, Illinois. DISCHARGE, IN CUBIC FEET PER SECOND

07/19/96 07/22/96 07/25/96 05/21/99 05/24/99 05/27/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/26/94 06/29/94

0

0

50

100

150

200

250

01/12/95 01/15/95 01/18/95

0

0

100

200

300

400

500

1,000

2,000

3,000

4,000

5,000

6,000

100

200

300

400

500

600

700

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
Blackberry Creek Detention Modeling Case Study 27

Figure 21. Comparison of flood frequencies and selected storm hydrographs simulated for 1996 and 2020 land uses and 

selected detention basin release rates on Blackberry Creek (subbasin 270), at the Kane and Kendall County, Illinois, line. DISCHARGE, IN CUBIC FEET PER SECOND

07/19/96 07/22/96 07/25/96 07/28/96 05/21/99 05/24/99 05/27/99

100.0 99.9 99.0 90.0 70.0 50.0 30.0 10.0 1.0 0.1 0.0

EXCEEDANCE PROBABILITY, IN PERCENT

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

2-year

10-year

100-year

06/23/94 06/26/94 06/29/94

0

0

50

100

150

200

250

300

1,000

2,000

3,000

4,000

5,000

6,000

100

200

300

400

500

600

700

01/12/95 01/14/95 01/16/95 01/18/95

0

0

100

200

300

400

500

EXPLANATION

2020 land use 0.08 release rate

2020 land use 0.10 release rate

2020 land use 0.12 release rate

2020 land use

1996 land use
28 Effect of Detention Basin Releases on Flood Flows—Application of Model to Blackberry Creek Watershed, Kane County, Illinois

Summary and Conclusions

The Kane County Department of Environmental and 

Building Management (KCDEM) developed a stormwater 

ordinance for managing continuing growth and protecting 

natural resources in Kane County. The ordinance specifies that 

detention storage should be constructed in all new development areas in the county and that detention basins should have 

a release rate set at 0.1 cubic feet per second per acre of developed area (ft3

/s-acre) for controlling the 100‐year flood. However, uncertainty remains about the extent of protection given 

by this release rate on the watershed scale. The U.S. Geological Survey (USGS), in cooperation with the KCDEM, 

undertook this study to determine the effect of detention basin 

release rates on flood flows for stormwater management in the 

Blackberry Creek watershed in Kane County.

The effects of stormwater detention basins with specified 

release rates are examined on a watershed scale with a Hydrological Simulation Program-FORTRAN (HSPF) continuoussimulation model. The outlet structure of the simulated 

detention basins was an orifice and a weir, and procedures for 

estimating the detention basin storage with a given release rate 

and for implementation in the HSPF models were developed 

and described. To facilitate future detention modeling as a tool 

for watershed management, a chart relating impervious area in 

a watershed to detention volume is presented. 

A case study of the Blackberry Creek watershed in Kane 

County, Illinois, a rapidly urbanizing area seeking to avoid 

future flood damages from increased urbanization, illustrates 

the effects of various detention basin release rates on peak 

flows and volumes and flood frequencies. A detention basin 

was simulated in each subbasin where urban development 

was projected to occur between 1996 and 2020. Simulated 

flows based on a 1996 land-use HSPF model were compared 

to those based on four projected 2020 land-use HSPF model 

scenarios: no detention, and detention basins with release rates 

of 0.08, 0.10, and 0.12 ft3/s-acre, respectively. 

Flood-frequency analyses and selected flood hydrograph 

plots showed the effect of increased urban development and 

implementation of detention basins with specific release rates 

in the watershed. Overall, the detention basin storm runoff 

hydrographs show reduction in flood peaks; however, the 

recession limbs were prolonged with higher discharge magnitudes. The release-rate effectiveness was evaluated by whether 

100-year flood-peak discharge could be maintained at or 

below the 1996 land-use conditions. 

The results of the simulations at 15 locations, which 

included the downstream ends of all major tributaries and strategic locations along the main stem, showed that a detention 

basin release rate of 0.10 ft3/s-acre, in general, could maintain 

postdevelopment 100-year peak flows at a similar magnitude 

to that of 1996 land-use conditions. Although the release rate 

is designed to reduce the 100-year peak flow, reduction of the 

2-year peak flow is also achieved for a smaller proportion of 

the peak. Results also showed that the 0.10 ft3/s-acre release 

rate was less effective in watersheds with relatively high 

percentages of preexisting (1996) development than in watersheds with less preexisting development.

Acknowledgments

The Kane County Department of Environmental and 

Building Management and the Illinois Department of Natural 

Resources–Office of Water Resources, in cooperation with 

the USGS–Illinois Water Science Center, conducted this 

investigation of stormwater management strategies for the 

Blackberry Creek watershed in Kane County. Darren Olson, 

of Christopher Burke Engineering, Ltd. (CBBEL), provided 

a detention basin sizing spreadsheet that was the basis of the 

detention basin spreadsheet developed in this study. Valuable input was received from the following technical reviewers: William Coon, USGS–New York Water Science Center; 

Karen Kosky, Kane County Department of Environmental and 

Building Management; Chad Ostheimer, USGS–Ohio Water 

Science Center; Loren Wobig, Illinois Department of Natural 

Resources–Office of Water Resources.

References Cited

Bedient, P.B., and Huber, W.C., 2002, Hydrology and floodplain analysis: Englewood Cliffs, N.J., Prentice-Hall, 763 p.

Bicknell, B.R., Imhoff, J.C., Kittle, J.L., Jr., Jobes, T.H., 

and Donigian, A.S., Jr., 2000, Hydrological simulation 

program—FORTRAN (HSPF) User’s manual for release 

12: Athens, Ga., U.S. Environmental Protection Agency 

Research Laboratory [variously paged].

Chow, V.T., Maidment, D.R., and Mays, L.W., 1988, Applied 

Hydrology: New York, McGraw–Hill, Inc., 572 p.

Donigian, A.S., Chinnaswamy, R.V., and Jobes, T.H., 1997, 

Conceptual design of multipurpose detention facilities for 

flood protection and nonpoint source pollution control: 

Mountain View, Calif., Aqua Terra Consultants, 151 p.

Dreher, D.W., Schaefer, G.C., and Hey, D.L., 1989, Evaluation of stormwater detention effectiveness in Northeastern 

Illinois: Northeastern Illinois Planning Commission, 135 p.

Flynn, K.M., Kirby, W.H., and Hummel, P.R., 2006, User’s 

manual for program PeakFQ annual flood-frequency 

analysis using Bulletin 17B guidelines: U.S. Geological 

Survey Techniques and Methods Book 4, Chapter B4, 42 p., 

accessed July 10, 2009, at http://pubs.usgs.gov/tm/2006/

tm4b4/.
References Cited 29

Interagency Advisory Committee on Water Data, 1982, Guidelines for determining flood flow frequency, Bulletin 17B of 

the Hydrology Subcommittee: Reston, Va., U.S. Geological 

Survey, Office of Water Data Coordination, 183 p. [Available from National Technical Information Service, Springfield, VA 22161, as report no. PB 86 157 278. Also available in PDF format (28 Mbyte file size) from the Federal 

Emergency Management Agency Web site http://www.fema.

gov/library/viewRecord.do?id=2360]

Kane County Stormwater Management, 2005, Countywide 

stormwater ordinance, accessed July 16, 2008, at 

http://www.co.kane.il.us/kcstorm/.

King County Stormwater Services, 2008, Stormwater facilities, accessed August 27, 2008, at http://www.kingcounty.

gov/environment/waterandland/stormwater/introduction/

facilities.aspx.

Konrad, C.P., 2003, Effects of urban development on floods: 

U.S. Geological Survey Fact Sheet FS–076–03, 4 p.

Luman, D., Joselyn, M., and Suloway, L., 1996, Critical Trends Assessment land cover database of Illinois, 

1991–1995: Champaign, Ill., Illinois Department of Natural 

Resources, 157 p.

Murphy, E.A., Straub, T.D., Soong, D.T., and Hamblen, C.S., 

2007, Hydrologic, hydraulic, and flood-hazard analysis of 

the Blackberry Creek watershed, Kendall County, Illinois: 

U.S. Geological Survey Scientific Investigations Report 

2007–5141, 27 p.

Northeastern Illinois Planning Commission, 1985, Survey of 

detention basin maintenance problems: Chicago, Ill., Northeastern Illinois Planning Commission. 

Price, T.H., 1997, Unit area detention volumes based on continuous simulation recommended for use with the DuPage 

Countywide stormwater management ordinance: Northeastern Illinois Planning Commission, prepared for Stormwater 

Management Division, Environmental Concerns, DuPage 

County, March 1997.

Price, T.H., 2003, Blackberry Creek watershed alternative 

futures analysis: Elmhurst, Ill., Conservation Design Forum, 

54 p.

Price, T.H., and Dreher, D.W., 1991, Investigation of hydrologic methods for site design in northeastern Illinois—Draft 

report, August 1991: Chicago, Ill., Northeastern Illinois 

Planning Commission [variously paged].

Sherwood, D.A., 2001, Effect of a vegetated stormwaterdetention basin on chemical quality and temperature of runoff from a small residential development in Monroe County, 

New York: U.S. Geological Survey Water-Resources Investigations Report 01–4099, 11 p., accessed July 10, 2009, at 

http://ny.water.usgs.gov/pubs/wri/wri014099/.

Soong, D.T., Ishii, A.L., Sharpe, J.B., and Avery, C.F., 2004, 

Estimating flood-peak discharge magnitudes and frequencies for rural streams in Illinois: U.S. Geological Survey 

Scientific Investigations Report 2004–5103, 158 p. and 

1 CD-Rom.

Soong, D.T., Straub, T.D., and Murphy, E.A., 2005, Continuous hydrologic simulation and flood-frequency, hydraulic, and flood-hazard analysis of the Blackberry Creek 

watershed, Kane County, Illinois: U.S. Geological Survey 

Scientific Investigations Report 2005–5270, 78 p.. 1 pl., and 

1 CD-Rom. 
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Appendix 1 
Appendix 1. Flood quantiles estimated for selected recurrence intervals based on Hydrological Simulation Program–FORTRAN analysis for the 1996 laland uses without detention basins, and 2020 projected land uses with detention basins and release rates of 0.08, 0.10, and 0.12 cubic feet per second pBlackberry Creek watershed in Kane County, Illinois. —Continued [ft3/s-acre, cubic foot per second per acre; tributaries shown on figure 2; QT, flood quantile at T-year recurrence interval, in cubic feet per second; presented QT are for 2, 10, 50, an

Sub- basin number 1996 land use without detention basin 2020 projected land use without detention basin 2020 projected land use with detention basin and 0.08 ft3/s-acre release rate 2020 projected land use with detention basin and 0.10 ft3/s-acre release rate 

Q2 Q10 Q50 Q100 Q2 Q10 Q50 Q100 Q2 Q10 Q50 Q100 Q2 Q10 Q50 Q100 

Route 38 Branch 10 26 59 91 105 38 67 93 104 24 55 86 100 24 55 86 100 

Elburn Run 22 54 104 145 162 110 152 187 201 36 72 107 121 36 72 107 121 

21 107 277 478 576 284 476 657 738 81 196 336 408 83 200 342 414 20 151 411 728 886 350 633 916 1,047 127 319 559 682 131 325 566 690 1

Seavey Road Run 33 60 158 284 349 65 164 287 350 57 152 272 335 57 152 272 335 

32 77 218 407 507 77 218 407 507 77 218 407 507 77 218 407 507 31 146 344 570 680 151 349 572 679 145 342 566 675 146 342 567 675 130 153 361 609 734 161 373 622 746 152 359 606 730 152 359 606 730 1

Prestbury Branch 41 12 36 71 90 40 98 168 203 4 10 20 26 4 10 20 26 

40 14 32 54 66 30 62 93 108 22 37 51 56 24 41 57 63 

Lake Run 57 74 205 373 460 74 204 373 460 74 204 373 460 74 204 373 460 

56 10 40 95 129 12 42 97 132 9 32 72 98 9 32 72 98 55 24 76 158 206 25 79 160 206 22 68 140 182 22 68 140 182 54 101 283 521 647 103 284 521 645 100 277 508 629 100 277 509 630 153 17 38 54 60 22 38 51 56 14 35 54 62 14 35 54 62 52 288 678 1,095 1,288 296 681 1,082 1,266 275 656 1,065 1,255 277 658 1,067 1,257 251 305 663 1,009 1,160 320 673 1,006 1,150 298 650 995 1,147 300 651 998 1,151 350 236 525 845 999 287 584 894 1,038 225 495 798 945 226 497 800 947 2

East Run 64 93 209 328 382 171 297 421 478 60 133 208 243 60 133 208 243 

63 115 285 481 576 321 546 751 841 73 165 273 327 74 169 278 332 62 65 157 274 335 222 367 505 567 44 89 138 162 48 95 148 173 61 61 144 249 303 213 363 510 576 70 131 195 225 78 148 222 257 60 39 89 151 182 124 258 407 480 59 114 173 201 64 129 200 234 
Appendix 1. Flood quantiles estimated for selected recurrence intervals based on Hydrological Simulation Program–FORTRAN analysis for the 1996 lland uses without detention basins, and 2020 projected land uses with detention basins and release rates of 0.08, 0.10, and 0.12 cubic feet per second pBlackberry Creek watershed in Kane County, Illinois. —Continued[ft3/s-acre, cubic foot per second per acre; tributaries shown on figure 2; QT, flood quantile at T-year recurrence interval, in cubic feet per second; presented QT are for 2, 10, 50, an

Subbasin 

number

1996 land use 

without detention basin

2020 projected land use 

without detention basin

2020 projected land use 

with detention basin and 

0.08 ft3/s-acre release rate

2020 projected land use 

with detention basin and 

0.10 ft3/s-acre release rate

Q2 Q10 Q50 Q100 Q2 Q10 Q50 Q100 Q2 Q10 Q50 Q100 Q2 Q10 Q50 Q100 

Aurora Chain-of-Lakes

79 4 13 29 39 25 93 207 275 1 2 4 5 1 2 4 5 78 5 12 21 26 12 29 50 60 7 11 16 18 7 13 18 21 77 30 102 207 265 166 325 494 575 29 74 127 153 31 77 130 157 76 65 208 398 497 278 502 711 803 82 190 304 357 87 199 314 367 75 30 115 271 370 284 611 938 1,085 45 142 295 386 52 162 329 425 74 4 5 6 6 6 7 8 9 4 5 5 5 4 5 5 5 73 32 91 177 225 249 668 1,139 1,361 45 111 196 241 52 129 229 282 72 3 9 19 24 26 72 137 172 1 3 5 7 1 3 5 7 71 4 9 16 20 16 47 94 120 6 11 16 18 6 12 18 21 70 21 46 74 88 74 235 487 633 34 74 118 139 38 86 143 171 

Blackberry Creek main stem

208 67 175 302 364 68 176 302 363 67 174 300 362 67 174 300 362 210 131 323 545 654 168 363 578 681 126 307 516 618 126 308 516 618 1213 136 347 612 748 257 510 782 912 113 279 485 590 114 281 487 592 1216 128 299 511 620 211 420 652 765 124 275 456 548 129 282 466 559 1218 138 312 526 635 216 433 674 791 135 291 473 565 140 298 484 578 1220 258 625 1,092 1,336 465 913 1,403 1,640 243 551 928 1,121 250 562 941 1,135 2223 295 711 1,237 1,511 501 989 1,526 1,786 280 637 1,075 1,300 287 647 1,085 1,309 2226 314 713 1,197 1,443 498 971 1,486 1,734 311 669 1,092 1,304 318 681 1,105 1,318 3230 441 985 1,638 1,970 613 1,229 1,916 2,250 442 951 1,550 1,851 450 964 1,567 1,868 4233 450 994 1,646 1,976 617 1,243 1,942 2,282 452 963 1,561 1,860 461 978 1,579 1,879 4236 457 984 1,605 1,916 663 1,254 1,881 2,179 450 942 1,508 1,789 461 959 1,530 1,812 4240 482 1,020 1,646 1,958 716 1,322 1,946 2,237 514 1,038 1,624 1,910 532 1,072 1,675 1,969 5250 636 1,380 2,262 2,706 870 1,771 2,786 3,284 678 1,405 2,236 2,646 702 1,450 2,302 2,722 7260 667 1,452 2,383 2,853 973 1,988 3,136 3,699 731 1,505 2,385 2,819 761 1,565 2,478 2,928 7265 529 1,300 2,286 2,801 832 1,811 2,926 3,474 598 1,359 2,269 2,728 630 1,417 2,343 2,805 6270 535 1,286 2,225 2,709 872 1,871 2,978 3,511 618 1,367 2,240 2,673 653 1,434 2,330 2,771 6
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Soong and others—Effect of Detention Basin Releases on Flood Flows—Application to Blackberry Creek Watershed, Illinois—Scientific Investigations Report 2009–5106

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