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Determining Peak-Discharge Frequencies in an Urbanizing Watershed: A Case Study July 1979 Approved for Public Release. Distribution Unlimited. TP-64

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4. TITLE AND SUBTITLE Determining Peak-Discharge Frequencies in an Urbanizing Watershed: A Case Study

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6. AUTHOR(S) Steven F. Daly, John C. Peters

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7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) US Army Corps of Engineers Institute for Water Resources Hydrologic Engineering Center (HEC) 609 Second Street Davis, CA 95616-4687

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12. DISTRIBUTION / AVAILABILITY STATEMENT Approved for public release; distribution is unlimited. 13. SUPPLEMENTARY NOTES Paper presented at the International Symposium on Urban Storm Runoff, University of Kentucky, Lexington, Kentucky, 23-26 July 1979. 14. ABSTRACT A case study is presented of a hydrologic investigation of the Red Run Drain-Lower Clinton River watershed, an area near Detroit, Michigan, that has undergone urbanization since the 1940's. The purpose of the study was to determine peak-discharge frequencies at gaged and ungaged locations for existing and future conditions. Population density was used as an indicator of urbanization in relationships defining unit hydrograph parameters and hydrologically significant impervious area. Input parameters for a single event rainfall-runoff simulation model (HEC-1) were developed to reflect watershed conditions in the years 1940, 1950, 1960 and 1975. The input parameters were verified by reconstructing observed flood events that occurred at these points in time. Sets of synthetic winter and summer storm hyetographs were input to HEC-1 to develop a series of curves for two gaging stations that relate peak discharge to magnitude of synthetic storm for each watershed condition. The curves were used to transform the series of recorded annual peak discharges at teach gage to a stationary series that reflects 1975 watershed conditions. Discharge frequency estimates were then developed for ungaged locations using winter and summer synthetic storms that were assigned exceedance frequencies consistent with actual exceedance frequencies at the gaged locations. Projections of future population density were the basis for developing HEC-1 input parameters representing year 2000 and 2025 watershed conditions. Estimates of peak discharge-frequencies for the future conditions were made at the gaged and ungaged locations using the methods described above. 15. SUBJECT TERMS peak runoff, flood peaks, storm runoff, peak discharge, frequency analysis, frequency curves, urban areas, urbanization

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Determining Peak-Discharge Frequencies in an Urbanizing Watershed: A Case Study

July 1979 US Army Corps of Engineers Institute for Water Resources Hydrologic Engineering Center 609 Second Street Davis, CA 95616 (530) 756-1104 (530) 756-8250 FAX www.hec.usace.army.mil TP-64

Papers in this series have resulted from technical activities of the Hydrologic Engineering Center. Versions of some of these have been published in technical journals or in conference proceedings. The purpose of this series is to make the information available for use in the Center's training program and for distribution with the Corps of Engineers. The findings in this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products.

DETERMINING PEAK-DISCHARGE FREQUENCIES IN AN URBANIZING WATERSHED - A CASE STUDY

S t e v e n F . Daly H y d r a u l i c E n g i n e e r , Corps o f E n g i n e e r s

D e t r o i t , Michigan 48231

John P e t e r s H y d r a u l i c E n g i n e e r , Corps o f E n g i n e e r s

The H y d r o l o g i c E n g i n e e r i n g C e n t e r D a v i s . C a l i f o r n i a 95616

A b s t r a c t . A c a s e s t u d y i s p r e s e n t e d of a h y d r o l o g i c i n v e s t i g a t i o n --- of t h e Red Run Drain-Lower C l i n t o n River w a t e r s h e d , a n a r e a near D e t r o i t , Michigan , t h a t h a s undergone u r b a n i z a t i o n s i n c e t h e 1 9 4 0 ' s . The purpose o f t h e s t u d y was t o d e t e r m i n e ~ e a k - d i s c h a r g e f r e q u e n c i e s a t gaged and ungaged l o c a t i o n s f o r e x i s t i n g and f u t u r e c o n d i t i o n s . P o p u l a t i o n d e n s i t y was used a s an i n d i c a t o r of u r b a n i z a t i o n i n r e l a t i o n s h i p s d e f i n i n g u n i t hydrograph p a r a m e t e r s and h y d r o l o g i c a l l y s i g n i f i c a n t imperv ious a r e a . I n p u t p a r a m e t e r s f o r a s i n g l e e v e n t r a i n f a l l - r u n o f f s i n l u l a t i o n model (HEC-1) were deve loped t o r e f l e c t w a t e r s h e d c o n d i t i o n s i n t h e y e a r s 1940, 1950 , 1960 and 1975. The i n p u t p a r a m e t e r s were v e r i f i e d by r e c o n s t r u c t i n g o b s e r v e d f l o o d e v e n t s t h a t occurxed a t t h e s e p o i n t s i n t i m e . S e t s o f s y n t h e t i c w i n t e r and summer s t o r m h y e t o g r a p h s were i n p u t t o HEC-1 t o d e v e l o p a s e r i e s o f c u r v e s f o r two g a g i n g s t a t i o n s t h a t r e l a t e peak d i s c h a r g e t o magni tude o f s y n t h e t i c s t o r m f o r e a c h w a t e r s h e d c o n d i t i o n . The c u r v e s were used t o t r a n s f o r m t h e s e r i e s o f r e c o r d e d a n n u a l peak d i s c h a r g e s a t each gage t o a s t a t i o n a r y s e r i e s t h a t r e f l e c t s 1975 w a t e r s h e d c o n d i t i o n s . D i s c h a r g e f r e q u e n c y e s t i m a t e s were t h e n deve loped f o r ungaged l o c a t i o n s u s i n g w i n t e r and summer s y n t h e t i c s t o r m s t h a t were a s s i g n e d exceedance f r e q u e n c i e s c o n s i s t e n t w i t h a c t u a l exceedance f r e q u e n c i e s a t t h e gaged l o c a t i o n s . P r o j e c t i o n s o f f u t u r e p o p u l a t i o n d e n s i t y were t h e b a s i s f o r d e v e l o p i n g HEC-1 i n p u t p a r a m e t e r s r e p r e s e n t i n g y e a r 2000 and 2025 w a t e r s h e d con- d i t i o n s . E s t i m a t e s o f peak d i s c h a r g e - f r e q u e n c i e s f o r t h e f u t u r e c o n d i t i o n s were made a t t h e gaged and ungaged l o c a t i o n s u s i n g t h e methods d e s c r i b e d above

I n t r o d u c t i o n --- I k t e r m i n i n g t h e impact o f u r b a n i z a t i o n on f l o o d

f l o w f r e q u e n c y i s an a r e a o f s u b s t a n t i a l i n t e r e s t f o r f l o o d c o n t r o l p l a n n i n g and d e s i g n and f o r s t u d i e s r e q u i r e d by t h e n a t i o n a l f l o o d i n s u r a n c e program I h i s paper r e p o r t s methodology used i n a Corps o f E n g i n e e r s s t u d y ( 7 ) t o e v a l u a t e c h a n n e l m o d i f i c a t i o n p r o p o s a l s f o r t h e Red Run D r a i n , which i s l o c a t e d immedia te ly n o r t h o f D e t r o i t i n t h e C l i n t o n River b a s i n The s t u d y was conducted t o d e t e r m i n e peak- d i s c h a r g e f r e q u e n c y c u r v e s a t two gaged and numerous ungaged l o c a t i o n s f o r e x i s t i n g (1975) l a n d u s e con- d i t i o n s a s w e l l a s f o r c o n d i t i o n s i n t h e y e a r s 2000 and 2025 Methodology i s r e p o r t e d h e r e i n f o r con- ver t i n g a n o n s t a t i o n a r y t ime s e r i e s o f a n n u a l peak

d i s c h a r g e s t o a s t a t i o n a r y t ime s e r i e s r e p r e s e n t i n g a s p e c i f i c s e t o f l a n d u s e c o n d i t i o n s , and p r o c e d u r e s a r e d e s c r i b e d f o r d e v e l o p i n g p e a k - d i s c h a r g e f r e q u e n c y c u r v e s a t ungaged s i t e s .

P r e v i o u s S t u d i e s

A number o f s t u d i e s r e l a t i n g t o t h e h y d r o l o g y o f S o u t h e a s t e r n Michigan have been r e p o r t e d ( 1 , 2 , 3, 4 , 5 , 6 ) . I n p a r t i c u l a r , B r a t e r and S h e r r i l l ( 2 ) pro- v i d e d t h e r e s u l t s o f an e x t e n s i v e p r o j e c t i n i t i a t e d i n 1964 t o d e v e l o p a p r o c e d u r e f o r e s t i m a t i n g f r e q u e n c y o f s t o r m r u n o f f f o r s m a l l b a s i n s i n v a r i o u s s t a g e s o f u r b a n i z a t i o n . R e s u l t s of t h a t p r o j e c t were used i n a number o f i n s t a n c e s i n t h e s t u d y d e s c r i b e d i n t h i s p a p e r .

*Paper presented at the International Symposium on Urban Storm Runoff, University of Kentucky, Lexington, Kentucky, July 23-26 1979.

Watershed C h a r a c t e r i s t i c s

The C l in ton River Watershed covers an a r e a of 760 squa re mi les i n the s o u t h e a s t e r n p o r t i o n of the lower p e n i n ~ u l a of Michigan (F igu re 1) The C l i n t o n River Watershed inc ludes both r u r a l and urban a r e a s , and roughly resembles a maple l e a f , w i th t he stem o r base t h e o u t l e t t o Lake S t . C l a i r . The Main Branch of the C l i n t o n River o r i g i n a t e s i n t he h i l l y coun t ry o f Oakland County, where a g r e a t number of l a k e s , rang- ing i n s i z e from a few a c r e s t o s e v e r a l square m i l e s , remain as a legacy of the l a s t pe r iod of g l a c i a t i o n . I t i s from these l akes t h a t the r i v e r o b t a i n s much of i t s base flow. The Main Branch flows i n a gene ra l s o u t h e a s t e r l y d i r e c t i o n for 69 m i l e s , through s e v e r a l sma l l e r urban a reas ( P o n t i a c , Roches ter , U t i c a ) , where i t i s joined by t he North and Middle Branches , i h i r h d r a i n r e l a t i v e l y r u r a l a r e a s of 201 and 77 square m i l e s , r e s p e c t i v e l y The conf luence of the t h r e e t r i b u t a r i e s , known l o c a l l y a s the "Forks Area ," produces the C l in ton River p rope r , which meanders t h r o ~ ~ g h a l e v e l p l a i n i n a g e n e r a l l y e a s t e r l y d i .

r e c t i o n f o r 11 m i l e s , through t h e C i t y o f M t . Clemens, t o i t s o u t l e t i n Lake S t . C l a i r .

Four. mi l e s upstream of the Forks Area the Main Branch i s joi.ned by the Red Run Drain . The Red Run, which d r a i n s an a rea of approximate ly 1b0 squa re m i l e s , o r i g i n a t e s i n the h e a v i l y urbanized n o r t h e r n suburbs of D e t r o i t , and flows i n a n o r t h e a s t e r l y d i r e c t i o n through t h e r a p i d l y u rban iz ing s e c t i o n s of wes t e rn Macomb County. (F igu re 2)

Three d i s t i n c t types of topography a r e e v i d e n t i n the C l i n t o n River Watershed: The h i l l y , l ake covered r eg ion t h a t comprises the head wa te r s of t h e Main Branch; t he r o l l i n g , wel l -dra ined coun t ry t h a t comprises t he watershed of the Middle and North Branches; and t h e f l a t , poo r ly d ra ined a r e a s t h a t extend i n a broad p l a i n a long Lake S t . C l a i r and comprise t he watershed of the Red Run. I t i s i n t h i s a r e a of poor ly d ra ined g l a c i a l t i l l t h a t t he m a j o r i t y o f development i n the watershed has taken p l a c e . The Red Run Drain and i t t r i b u t a r i e s have been ex--

Figure 1. C l in ton River Watershed

t e n s i v e l y modif ied t o provide adequate c a p a c i t y for a v a i l a b l e f o r t h e pe r iod 1960-1975 from t h e South- s torm d ra inage from the urban a r e a s . However, t he e a s t e r n Michigacl Raingage Network, o f which about 25 r a t e of u r b a n i z a t i o n has exceeded the r a t e of s t a t i o n s l i e i n and around t h e C l i n t o n River Water- d ra inage improvement i n r e c e n t years and wlde-spread shed. Streamflow reco rds a v a i l a b l e fo r t h e 30 U.S. ove r l and and basement f l ood ing has r e s u l t e d . Geo log ica l Survey gaging s t a t i o n s on t h e C l ~ n t o n

River and t r i b u t a r i e s extend t o a maxirnum pe r iod o f Sumr.i~i >f Ava i l ab l e Data 41 y e a r s f o r t h e Yain Branch C l i n t o n River gage a t

Noravian Dr ive i n M t . Clemens. Meteorologic and s treamf low reco rds for t h e

C l i n t o n Rivec Basin a r e r e l a t i v e l y comprehensive and provide e x c e l l e n t coverage of t h e more r e c e n t f l oods . Parameter Development and HEC-1 C a l l b r a t l o n P r e c i p i t a t i o n r eco rds f o ~ ~ i l e C ~ t y of M t . Clemens, cons ide red t y p i c a l o f t he b a s i n , a r e a v a i l s b l e from Basin rnodellng c o n s l s t s of d e s c r i b i n g t h e topo- about 1897 t o tllp p i % o r . Yoully r a i n f a l l d a t a a r e l o g l c s t r u c t u r e of a bas ln (drainage b a s ~ n bound-

PLUM BROOK D A 2% 84 SO MI

HENRY GRAMM D A 21 08 SQ MI

TWELVE TOWNS D A 37 13 90 MI

0 S E M C O G R A I N G A G I N G S T A T I O N S

U . S . G . S . S T R E A M A G A G I N G S T A T I O N

W A T E R C O U R S E

- -- - S U B B A S I N B O U N D R Y

Flgure 2 Red Run Drain

3

RED RUN B A S I N

Table 1. L i s t i n g of U.S .G.S . Gages

STATION --

Main Branch

04161000 Clinton R. @ Auburn Hts 04161100 Galloway Cr nr. Auburn Hts . 04161540 Paint Cr at Rochester 04168000 Stoney Cr nr . Washington

Red Run Watershed

04162900 Big Beaver nr.. Warren 04163400 Plum Brook at Utica

Clinton River -- 04164000 Clinton River nr. Eraser 04164500 N. Br Clinton River nr. Mt . Clemens 28 04165500 Clinton River at Ht. Clemens

i n p u t t o t h e model i s a t ime h i s t o r y of p r e c i p i t a t i o n f o r each subbas in f o r t h e d u r a t i o n of t h e s to rm even t under s tudy . The b a s i c ou tpu t i s computed f l o o d hydrographs t h a t r e p r e s e n t a t ime h i s t o r y of t h e hydro log ic response o f t h e b a s i n s and s t r eam channe l s under s tudy .

Computer Program HEC-1 ( 8 ) u s e s a lumped-para- meter approach f o r de termining runof f from each sub- a r e a under c o n s i d e r a t i o n , i . e . , t h e parameters and/or computa t ions f o r a p a r t i c u l a r subbas in a r e assumed t o app ly f o r i t s e n t i r e a r e a . Because o f t h e many p o i n t s of i n t e r e s t throughout t h e Red Run b a s i n and t h e Lower C l i n t o n R ive r , t h e s tudy a r e a was d iv ided i n t o a t o t a l o f 22 subbas ins r ang ing i n s i z e from roughly 5 t o 200 squa re mi l e s a s shown i n t h e schemat ic diagram i n F i g u r e 3 .

Unit Hydrograph Parameters - To develop t h e r e q u i r e d u n i t hvdrographs f o r p a s t , e x i s t i n g and f u t u r e land u s e c o n d i t i o n s f o r t h e numerous subbas ins of t he

a r i e s , s t r eam channe l s , and t h e l o g i c a l r e l a t i o n s h i p s C l i n t o n River Watershed, r e g i o n a l r e l a t i o n s h i p s were between t h e d ra inage a r e a s and s t r eam channe l s ) and determined fo r u n i t hvdrograph parameters In ad- d e f i n i n g t h e parameters t h a t d e s c r i b e t h e p r e c i p i t a - d i t i o n , u n i t hydrograph parameters f o r f i v e r u r a l t i on - runof f response of t h e subbas ins and t h e subbas ins were determined by o p t i m i z a t i o n t echn iques channels t h a t comprise t h e bas in . The b a s i c d r i v i n g from recorded d a t a

HENRY GRAMM z u >

+ + + cx - c 3 -

z z 2 L z z z - RED RUN 0 / 5 BEAR CR .2 - -

z z 2

E

z SCHOENHERR D R A I N

SCHOENHERR OR LOCAL INFLOW AT

S T E R L I N G D R A I N

RED RUN U / S F I F T E E N MILE RED RUN

S T E R L I N G D R A I N ( 1 5 M I L

RED RUN U I S PLUM BROOK

C L I N T O N R LOCAL INFLOW A T RED RUN

FORKS f lREA ( R E S E R V O I R ROUT1

5 0 C L I N T O N R A T M O R A V I A N OR

C L I N T O N R A T FRASER a C L I N T O N R L O C A L lNFLOW AT FRASER

C L I N T O N R LOCAL

0 L Y u m R E n

0 - HYOROGRAPH

R n l l l l N T I R E n r k

- RESERVOIR

Figure 3 . HEC-1 Schematic Diagram

4

Table 2 Drainage Basin C h a r a c t e r i s t i c s and Uni t Hydrograph Parameters

Popu la t ion USGS Densi ty

Drainage Gage Area Pe r sons / Qp( l ) TR (2) Basin No. S a . . M i . So. Hi.. CFS H r s -- -- - --

Big Beaver Creek near IJarren, M I 4-1629.0 23.5 774 799 13 .0

Plum Brook near U t i c a , 1II 4-1633.0 22.9 731 779 15.9

'ouge River Birmingham, PI1 4-1660.0 36.9 1212 1107 12 .5

Rouge River S o u t h f i e l d , M I 4-1661. 0 88 .0 1390 2288 15. .0

Rouge River D e t r o i t , M I 4-1665.0 185.0 2710 3700 27..0

C l in ton River Xt. Clemens, MI 4-1655.0 734 .0 1000 98 36 38 . O

XcBride Drain near >facomb, M I 4-1644.5 5.8 11 4 223 9 . 3

Tupper Brook Ray Cen te r , M I 4-1642 ..5 8 .6 6 0 318 5 .. 0

Evans Di t ch S o u t h f i e l d , "I1 4-1662 .. 0 9 . 5 2376 603 12 .0

Eas t Branch Coon C r . Armada, M I 4-1643.0 13 .0 56 520 10 .0

Gloede Di t ch near Waldenburg, M I 4-1652.0 1 6 . 0 560 432 1 4 . 1

Upper Rouge River Farmington, M I 4-1663.0 17 .5 1129 700 10 .0

Red Run n e a r Royal Oak, M I 3 6 . 5 7500 5110 4 .. 0

(1) Qp = u n i t hydrograph peak d i scha rge .

( 2 ) TR = pe r iod of r i s e of u n i t hydrograph..

C r l t e r i a fo r r e l a t i n g u n i t hydrograph parameters t o watershed c h a r a c t e r i s t i c s fo r use i n s o u t h e a s t e r n Michigan were g iven by B r a t e r and S h e r r i l l ( 2 ) U ~ l t hydrograph parameters fo r 13 gaged b a s i n s i n south- e a s t e r n Michigan a r e summarized i n Table 2 The u n i t hydrograph parameters i n Table 2 a r e fo r average u n i t hydrographs developed from a number of storms fo r each b a s i n Extens ive a n a l y s i s by Bra t e r and Sher- r i l l showed t h a t popu la t ion d e n s i t y and d ra inage a r e a were t h e most s i g n i f i c a n t watershed c h a r a c t e r i s t i c s i n de termining u n i t hydr ograph parameters Data from Table 2 were en t e red i n t o HEC's m u l t i p l e Linear Re- g r e s s i o n computer program t o develop equa t ions fo r u n i t hydrograph peak d i s c h a r g e , Q , and pe r iod of r i s e , Tr. The r e s u l t i n g equa t ions % r e g iven below:

Qp = a n t i l o g (l.85+.69410gA+.000099Pd) ( 1 )

T = a n t i l o g ( 66+ 3591ogA- 000067Pd) ( 2 )

where :

Q =peak d i scha rge of u n i t hydrograph i n CFS P

T , = t i m e of r i s e of u n i t hydrograph i n hours

A=drainage a r e a i n square m i l e s

P =popu la t ion d e n s i t y i n pe r sons per sq. m i l e d

The e r r o r i n u s i n g equa t ion 1 t o e s t i m a t e Q f o r t h e 1 3 b a s i n s ranges from .3% t o 33%, wi th a n av&rage of 10%. The c o r r e l a t i o n c o e f f i c i e n t fo r equa t ion 1 i s .991. The e r r o r i n u s ing equa t ion 2 t o e s t i m a t e T f o r t h e 13 b a s i n s ranges from 4% t o 95%, wi th a; average of 24%. The c o r r e l a t i o n c o e f f i c i e n t f o r equa t ion 2 i s .831.

Equat ions 1 and 2 were used t o develop u n i t hydrogr aph parameters f o r t h e ungaged subbas ins i n t h e Red Run bas in . Required popu la t ion d e n s i t i e s fo r t h e y e a r s 1940, 1950, 1960, and 1975 were ob ta ined from census d a t a . Popu la t ion p r o j e c t i o n s f o r t h e y e a r s 2000 and 2025 were ob ta ined from t h e South- e a s t e r n Michigan Council of Governments. To f a c i l i - t a t e u s e of HEC-1, v a l u e s f o r Q and T from equations

1 and 2 were t ransformed toPequ iv21en t v a l u e s of Snyder u n i t hydrograph parameters , t and C . Adopted v a l u e s f o r t h e s e parameters a r g shown Pn Table 3.

Table 3. Uni t Hydrograph Parameters and Impervious Areas f o r t h e Red Run Drain

F a s i n .-- --- sq. A ~ i . 1"' Twelve Town 37.13 10.2

j Bcnry Gramm 21.08 - - -,

Local Inflow a t Bear Creek

Bear Creek

1 Big Beaver I

Local Inflow a t S ter l ing

I i Plum Brook i i I---.

j (1) t - Snyder "Standard" Lag i n Hours P

I (2) C - Snyder Peak Discharge Coeff ic ient P I

(3) Inp. - Hydrologically s ign i f i cant imper.vious area expressed as a proportion of subbasin area

I n f i l t r a t i o n Ana lys i s - Hydrographs recorded f o r e i g h t subbas ins were analyzed t o determine average s o i l i n f i l t r a t i o n c a p a c i t y . I n a d d i t i o n , d a t a from o t h e r subbas ins of t h e C l i n t o n R ive r and t h e a d j a c e n t R ive r Rouge were analyzed and publ ished by Bra t e r and S h e r r i l l ( 2 ) . There i s c o n s i d e r a b l e s c a t t e r around t h e ave rage seasona l v a l u e s , depending p r i m a r i l y on an t eceden t r a i n f a l l and evapo- t r ansp i r a t i on . The adopted average va lues f o r i n f i l t r a t i o n were .40 inch/hour f o r summer c o n d i t i o n s and .10 inch/hour fo r

e-F-- eon&&io*s ~-~ ~ - - ~ ------

Impervious A r e ~ . An impor t an t e f f e c t of u rban iza - t i o n i s t o c r e a t e a d d i t i o n a l impervious a r e a . An e s t i m a t e f o r t he a r e a o f impervious s u r f a c e s may be made from a e r l a l photographs , but a l l p r e c i p i t a t ~ o n on such i m p e r v ~ o n s a r e a s does no t c o n t r i b u t e t o su r - f a c e r u n o f f . For t h i s r ea son , Bra t e r (2 ) employed t h e concept of a "Hydrologica l ly S i g n i f i c a n t Imper- v ious Area" (HSIA), which r e p r e s e n t s t he pe rcen t of t he t o t a l a r e a ryhich always contributes a runoff equa l t o t h e t o t a l p r e c l p i t a t l o n mlnus r e t e n t i o n , o r , i n o t h e r words, a lmost 100% r u n o f f . Values fo r HSIA can be de r ived from t h e a n a l y s i s of hydrographs r e s u l t i n g from l a r g e s torms o c c u r r i n g a f t e r a long summer d r y s p e l l , when t h e i n f i l t r a t i o n c a p a c i t y of t he pervious p o r t i o n i s ve ry h igh and t h e r e f o r e t h e e n t i r e s u r f a c e runof f i s de r ived from t h e Hydro- l o g i c a l l y S i g n i f i c a n t Impervious Area. I n south- e a s t e r n Michigan, t h e HSIA i s approximate ly twenty f i v e pe rcen t of t h e g ros s phys i ca l impervious a r e a a s de termined from a e r i a i photographs. B r a t e r showed a c o r r e l a t i o n between HSIA and popu la t ion d e n s i t y , P , f o r twelve watersheds i n s o u t h e a s t e r n Michigan ( 2 7 . This r e l a t i o n s h i p i s a s fo l lows:

HSIA = 1.38 P d ( 3 )

where :

Pd = t he popu la t ion d e n s i t y i n thousands of persons per square mi l e

RSIA i s i n pe rcen t of t o t a l a r e a

P r e c i p i t a t i o n - I n order t o s imu la t e t he hydro log ic response of t he C l i n t o n River Basin us ing t h e HEC-1 program, i t was neces sa ry t o review and c o l l e c t t h e per t -he f l r p iecIpi' m€i-o~-da~tZi T i ~ f K i X - t h e T F g i ~ h ~ ~ f o ~ ~ 5 number of h i s t o r i c s torms. P r e c i p i t a t i o n amounts were i n p u t i n t o t h e HEC-1 program on a subbas in b a s i s u s i n g t h e i h i e s s e n polygon or i s o h y e t a l method, de- pending on t h e e x t e n t of t h e d a t a a v a i l a b l e .

Stream Flow Rout ing - Stream flow r o u t i n g was done u s i n g t h e Modified Pu l s methods. With t h e Modified Pu l s method, d i s c h a r g e i s cons idered a unique func- t i o n of s t o r a g e . A number of reaches were e s t ab - l i s h e d fo r t h e Main Branch of t h e C l i n t o n R ive r and t h e Red Run Drain . S to rage volumes v e r e determined fo r each r each u s i n g the REC-2 Vater Su r face P r o f i l e s Program. (11) Discharge-s torage r e l a t i o n s h i p s were then developed t o provide t h e r e q u i r e d inpu t fo r t h e HEC-1 program.

C a l i b r a t i o n and V e r i f i c a t i o n - S i x s e p a r a t e HEC-1 d a t a models were developed i n t h i s s t u d y , r ep re - s e n t i n g d i f f e r e n t s t a g e s of t h e development and ur- b a n i z a t i o n of the C l i n t o n River Watershed. These nodels r e p r e s e n t c o n d i t i o n s i n the 19401s , 1 9 5 0 1 s , 19601s , 1 9 7 0 1 s , yea r 2000, and year 2025. The e i g h t l i s t o r i c s torm e v e n t s l i s t e d i n Table 4 were simu- l a t e d t o v e r i f y t h a t t h e parameters used were reasonable . From gage r e c o r d s , f l ood hydrographs dere determined f o r t he C l i n t o n River a t F r a s e r , which inc ludes runof f from both the Upper C l i n t o n

0 C O M P U T E D F L O W

HOURS 2 M A Y

Figure 4. Hydrograph F.eproduction

CLINTON R. AT FRASER 25 - 29 JUNE 1968

30 0 COMPUTED FLOW

I O

24 4 8 7 2 9 6

HOURS

Figure 5 , Hydrograph Reproduction

o C O M P U T E D F L O W

-- O B S E R V E D F L O W

HOURS

Figure 6. Hydrograph Reproduction

River and the Red Run Drain; the North Branch at Mt. Clemens, which includes runoff from the North Branch; and the Clinton River at Mt. Clemens, which includes runoff from almost the entire Clinton River Basin. The rainfall associated with each historic event was input to HEC-1 and computed flood hydrographs were compared to the observed hydrographs. The infiltra- tion parameter DLTKR, which is an index of antecedent moisture conditions, ( 8 ) was calibrated within rea- sonable limits to provide the best hydrograph repro-. duction. Typical hydrograph reproductions are shown in Figures 4 , 5, and 6 .

Frequency Curves At Gaged Sites

Two key stream gage sites in this study are the Clinton River near Fraser and the Clinton River at Mt, Clemens. The Fraser gage has been in operation since 1947 and measures runoff from a 444 square mile area that includes the Upper Clinton River and the Red Run Drain. The Mt Clemens gage has been in operation since 1934 and measures runoff ~IOIII i 3 4 square miles, which is nearly the entire Clinton River basin.. Records from these two gages were of substantial importance in this study for calibrating the rainfall-runoff simulation model, and for assign- ing the exceedance frequencies to synthetic storm- loss rate combinations.

Peak Discharge Peak Discharge

a t F r a s e r a t M t . Clemens

Table 4. H i s t o r i c Storm Events Used f o r The t ime s e r l e s of annual peak d i scha rges a t V e r i f i c a t i o n and C a l i b r a t i o n each s i t e i s n o n s t a t i o n a r y and nonhomogeneous - non-

s t a t i o n a r y because of t he time-dependent e f f e c t s of urban development; nonhomoge~leous because i n some y e a r s a winter event produces t he annual maximum d i s c h a r g e , whereas i n o t h e r yea r s a summer event produces t h e annual maximum. Winter runoff e v e n t s a r e c h a r a c t e r i z e d by cyc lon ic storms and ve ry low l o s s r a t e s , summer e v e n t s by thunders torms and relatively l a r g e l o s s r a t e s . Ihe following pro- cedures were used f o r transforming t h e recorded annual peak discharges a t F ra se r and M t . Clemens I n t o consistent s e r l e s t h a t r e f l e c t s e x l s t l n g land use c o n d l t l o n s and channel c h a r a c t e r l s t l c s ( 1 2 )

As i n d i c a t e d p rev ious ly , i npu t d a t a s e t s f o r HEC-1 were developed and c a l i b r a t e d t o r e f l e c t e x i s t - i ng watershed c o n d i t i o n s and c o n d i t i o n s i n 1960, 1950, and 1940 S y n t h e t i c winter and summer s torm e v e n t s were prepared us ing s torm p a t t e r n s ( i e , t ime d i s t r i b u t i o n s ) developed by Bra t e r and S h e r r i l l ( 2 ) They found t h a t :

"Typical l a r g e r a in s to rms i n S o u t h e a s t e r n Michigan have a n e a r l y symmetrical t ime d i s t r i b u t i o n wi th t he maximum hour near t h e c e n t e r of t he r a i n storm I n winter t he maximum hour c o n t a i n s about 24 pe rcen t of t h e r a i n and i n summer the maximum hour u s u a l l y provides about 55 pe rcen t of t he t o t a l storm r a i n f a l l . "

The magnitude of a "base" s torm was f i x e d by adop t ing a 25-year r ecu r rence i n t e r v a l , 24-hour dur-

SUMMER WINTER

a t i o n p l e c i p i t a t i o n depth from NOAA's Technica l Paper No 40 ( 9 ) . The r ecu r rence i n t e r v a l of 25 y e a r s was a r b i t r a r y . I t was not assumed i n t h e approach des- c r i b e d h e r e i n t h a t t he frequency of runoff i s equal t o t he f requency a s s o c i a t e d wi th the s y n t h e t i c s torm Ra the r , t h e purpose was t o e s t a b l i s h a base storm fo r u se i n subsequent s t e p s i n t he a n a l y s i s

S i x s y n t h e t i c storms for each season , summer and w i n t e r , were developed by app ly ing s c a l r n g r a t i o s t o t h e base storms Ra t io s were s e l e c t e d so t h a t peak d i s c h a r g e s r e s u l t i n g from the stornis would cover t h e range of d i scha rges r equ i r ed t o de f ine d ischarge- f requency curves a t the Fraser and M t Clemens gage l o c a t i o n s . Winter s y n t h e t i c storms were developed us ing s c a l i n g r a t i o s of 2 , 6 , 1 0 , 1 4 , 1 .8 and 2 2 Summer s y n t h e t i c storms were developed wi th r a t i o s of . 2 5 , 5 , 1 . 0 , 1 5 , 2 0 , and 2 5

The m u l t i p l a n - m u l t i r a t i o c a p a b i l i t y of HEC-1 pe rmi t t ed c a l c u l a t i o n of d i scha rge hydrographs f o r s i x s torms and four s e t s of runoff parameters ( f o r watershed cond i t i ons i n 1975, 1960, 1950, and 1940) i n one run of the program. Hence two runs were r e q u i r e d - one f o r summer cond i t i ons and one fo r winter c o n d i t i o n s . R e s u l t i n g r e l a t i o n s h i p s f o r c a l - c u l a t e d peak d i scha rge ve r sus s c a l i n g r a t i o f o r t h e F ra se r and M t Clemens gages a r e shown i n F igu res 7 and 8 . The r e l a t i o n s h i p s were used t o t ransform each r eco rded annual peak d i scha rge ( f o r each season) t o an e x i s t i n g - c o n d i t i o n annual peak.. This was achieved by e n t e r i n g t h e a p p r o p r i a t e s e t of curves hor izon- t a l l y w i t h t h e recorded peak d i scha rge t o t he i n t e r - s e c t i o n with a curve ( o r i n t e r p o l a t e d curve) f o r t he

year i n which the d i scha rge was r eco rded , and then moving v e r t i c a l l y t o an i n t e r s e c t i o n wi th t h e 1975 cu rve , from which the t ransformed peak d i scha rge could be determined The l a r g e s t of t he two t r a n s - formed peaks f o r each year was inco rpo ra t ed I n a t i m r s e r i e s of annual peaks S t a t i s t i c a l a n a l y s e s of t he r e s u l t i n g s e r i e s was performed us ing t echn iques i n B u l l e t i n 17 o f t he Water Resources Council (10) The r e s u l t i n g f requency curves a r e shown i n F igu res 9 and 10 Also shown a r e frequency curves based on ob- served (unt ransformed) peak d i scha rges Urban iza t ion has had a s u b s t a n t i a l i n f luence on the f requency curve f o r F r a s e r , whereas the i n f luence a t M t Clemens i s minor

Seasonal Frequency Curves At F r a s e r

Subsequent developiwnt of d i scha rge f requency cu rves f o r ungaged s i t e s r equ i r ed s e p a r a t e f requency curves f o r w in t e r and summer cond i t i ons f o r t h e C l i n t o n River a t F r a s e r . The curves a r e shown i n F igu re 11. The annual curve i s t h e same a s shown i n Figure 9. The win te r curve was obta ined g r a p h i c a l l y u s i n g Weibull p l o t t i n g p o s i t i o n s f o r t h e transforlned win te r peaks. The s e r i e s of summer peaks was t runca - t e d because f o r a number of y e a r s t he observed summer peaks were smal ler than t h e base va lue used by t h e U.S. Geologica l Survey a s a b a s i s f o r pub l i sh ing in s t an t aneous peaks. The sumlller f requency curve was t h e r e f o r e ob ta ined by s u b t r a c t i o n us ing t h e fo l lowing equa t ion :

SUMMER WINTER

Figure 8. Peak Discharges v s R a t i o s of T o t a l R a i n f a l l a t t h e Tlt. Clemens Gage

30-- ----. Frequency Curve Using Annual Series

Frequency Curve Using Corrected Annual Series

-- - - Confidence L i m i t s f o r Corrected Annual Ser ies

e Weibull P l o t t i n g P o s i t i o n

F i g u r e 9 . Frequency Curve a t F r a s e r

where:

PSUFmEK = Exceedance p r o b a b i l i t y f o r a g i v e n d i s c h a r g e on t h e summer-season f r e - quency c u r v e .

PWIN,.dR= Exceedance p r o b a b i l i t y f o r a g i v e n d i s c h a r g e on t h e w i n t e r - s e a s o n f r e - quency c u r v e .

S y n t h e t i c w i n t e r and summer s t o r m s were b a s e d on c r i t e r i a from NOL4A's T e c h n i c a l Paper No. 40 ( 9 ) and t h e t ime d i s t r i b u t i o n s d e v e l o p e d by B r a t e r and S h e r r i l l ( 2 ) . A p p l i c a t i o n of a r e a l a d j u s t m e n t s from T e c h n i c a l P a p e r No. 40 t o p o i n t r a i n f a l l s o f v a r i o u s d u r a t i o n s r e s u l t s i n s t o r m h y e t o g r a p h s t h a t a r e a f u n c t i o n of d r a i n a g e a r e a s i z e . T h e r e f o r e , s e p a r a t e HEC-1 r u n s were made u s i n g s t o r m h y e t o g r a p h s a s - s o c i a t e d w i t h d r a i n a g e a r e a s o f 1 0 s q u a r e m i l e s and 400 s q u a r e m i l e s . Peak d i s c h a r g e f o r any p a r t i c u l a r (ungaged) d r a i n a g e a r e a s i z e was o b t a i n e d by l o g - a r i t h m i c i n t e r p o l a t i o n between t h e peak d i s c h a r g e a s s o c i a t e d w i t h t h e s t o r m h y e t o g r a p h s f o r 10 s q u a r e m i l e s and 400 s q u a r e m i l e s .

= Exceedance p r o b a b i l i t y f o r a g i v e n Winter and summer f r e q u e n c y c u r v e s were deve lop- P ~ ' ~ u A L d i s c h a r g e on t h e a n n u a l ( a l l - r e a s a n ) e d a t a l l ungaged l o c a t i o n s of i n t e r e s t , f o r e x i s t i n g

f r e q u e n c y c u r v e . l a n d u s e c o n d i t i o n s and f o r l a n d u s e c o n d i t i o n s i n t h e y e a r s 2000 and 2025, u s i n g t h e t e c h n i q u e s d e s - c r i b e d above . Winter and summer f r e q u e n c y c u r v e s f o r

The a v a i l a b l e t r a n s f o r m e d summer peaks a r e p l o t t e d i n a g i v e n l a n d u s e c o n d i t i o n were t h e n combined t o ~ i ~ ~ ~ ~ e 1 1 f o r co lnpar i son u s i n g ' r l z ibu l l p l o t t i n g o b t a i n a n a n n u a l c u r v e b a s e d on t h e p r o b a b i l i t y o f

p o s i t i o n s . u n i o n o f i n d e p e n d e n t e v e n t s . F i g u r e 12 shows a t y p i c a l s e t o f f r e q u e n c y c u r v e s f o r a n ungaged l o c a -

Frequency Curves At Ungaged S i t e s t i o n .

The b a s i s f o r d e v e l o p i n g p e a k - d i s c h a r g e f r e - quency c u r v e s a t ungaged s i t e s t h r o u g h o u t t h e 140 F i n d i n g s s q u a r e m i l e Red Run Bas in was t o u s e b a l a n c e d s y n t h e t i c s t o r m s a s i n p u t s t o c a l i b r a t e d SEC-1 models The Red Run D r a i n and Lower C l i n t o n R i v e r w a t e r - f o r t h e b a s i n . S y n t h e t i c s t o r m - - l o s s r a t e combina- s h e d s have under gone u r b a n i z a t i o n s i n c e t h e 1 9 4 0 ' s . t i o n s were a s s i g n e d exceedance Erequencies i n a c - The e f f e c t of t h i s u r b a n i z a t i o n on t h e peak d is - . c o r d a n c e w i t h exceedance f r e q u e n c i e s o f c a l c u l a t e d c h a r g e s r e c o r d e d a t t h e i r a s c r and M t . Clemens g a g e s peak d i s c h a r g e s o b t a i n e d from t h e p r e v i o u s l y d e v e l o p - c a n be s e e n i n F i g u r e s 7 and 8. U r b a n i z a t i o n h a s had ed f r e q t l ~ n ~ : y c u r v e s f o r F r a s e r . a s u h s t a n t i a l i n f l u e n c e on t h e f r e q u e n c y of d i s c h a r g e

f o r F r a s e r , a s shown i n F igu re 9 . The peak d i scha rge a t Fraser i s comprised a lmost e n t i r e l y of runoff from t h e Red Run Drain , which peaks much sooner t han runof f from t h e main branch of t he C l in ton River . The Red Run h a s been s u b s t a n t i a l l y urbanized, and s o t h i s change i n f requency i s no t unexpected. The i n f l u e n c e o f u r b a n i z a t i o n a t M t . Clemens i s minor a s shown i n F igu res 8 and 10. Peak d i scha rges a t M t . Clemens a r e a combination o f runof f from the North Branch Water- shed, l a r g e l y r u r a l , and t h e Red Run Drain. Urbani- z a t i o n has decreased t h e peaking t ime of t h e Red Run Drain , which tends t o move a p a r t t h e time of occur- rence of t h e peak runof f r a t e s o f t h e North Branch and t h e Red Run Drain. This phenomenon has tended t o c o u n t e r a c t t h e i n c r e a s e i n peak d i scha rge r a t e s due t o u r b a n i z a t i o n .

Summa2 -- The development of peak-discharge f requency

e s t i m a t e s a t ungaged l o c a t i o n s i n an u rban iz ing watershed f o r e x i s t i n g and f u t u r e cond i t i ons i s , i n our op in ion , one of t he most challenging t a s k s a h y d r o l o g i s t can f ace . Three f a c t o r s a ided subs t an - t i a l l y i n t h e conduct of t h e s tudy ; (1) a v a i l a b i l i t y of r e s u l t s of previous e x t e n s i v e s t u d i e s p e r t a i n i n g t o t h e hydrology of Sou theas t e rn Pfichigan, ( 2 ) a r e l a t i v e abundance of p r e c i p i t a t i o n d a t a and ( 3 ) t h e f i n d i n g o f a s t a t i s t i c a l l y s i g n i f i c a n t index of u r - b a n i z a t i o n , popu la t ion d e n s i t y , t o which runoff para- meters could be r e l a t e d i n a convenient f a sh ion .

The b a s i c approach was t o use a s i n g l e even t r a i n f a l l - r u n o f f model t o t r ans fo rm n o n s t a t i o n a r y , nonhomogeneous s e r i e s of recorded annual peak d i s - charges t o c o n s i s t e n t s e r i e s r e p r e s e n t i n g e x i s t i n g and f u t u r e c o n d i t i o n s . The problem of nonho~nogeneity was handled by us ing s e p a r a t e a n a l y s e s for t h e summer and winter seasons . N o n s t a t l o n a r l t y was t r e a t e d by developing a s e t of s to rm magnitude vs . peak d i s - charge r e l a t i o n s h i p s f o r v a r i o u s p o i n t s i n t ime and u s i n g t h e s e r e l a t i o n s h i p s t o t ransform n o n s t a t i o n a r y s e r i e s t o s t a t i o n a r y ones. I n u t i l i z i n g s y n t h e t i c s torms t o develop peak d i s c h a r g e s for ungaged loca - t i o n s , s torm-loss r a t e combinations were a s s i g n e d exceedance E r + q n ~ n c i e s equa l t o t h e exceedance f r e - quenc ie s of c a l c u l a t e d peak d i scha rges a t t h e gage a t F ra se r .

Acknowledgements

The o r i g i n a l s tudy was performed t o accompany t h e Phase I , Plan Formula t ion Nemorandum of t h e Genera l Design Memorandum and Environmental Impact Sta tement fo r t h e a u t h o r i z e d Red Run Drain and lower C l i n t o n River , Michigan, Flaod Control M ~ j o r Drainage and A l l i e d Purposes p r o j e c t . The w r i t e r s exp res s t h e i r thanks t o t h e many people of t h e Hydrologic Engineer ing Center and t h e D e t r o i t D i s t r i c t oE the Corps o f Engineers who c o n t r i b u t e d t h e i r w o ~ k , sup- p o r t , guidance and encouragement.

F igu re 10 . Frequency Curve a t P I t . . Clenens

WINTER PEAKS o SUMMER PEAKS

Correc ted Annual Curve.

Der ived Summer Curve

EXCEEDENCE FREQUENCY - PERCENT

Figure 11. Seasonal Frequency Curves a t F ra se r

F igu re 1 2 . Typ ica l Frequency Curves a t an Ungaged Locat ion

1 2

Ref ex ences

1 . B r a t e r . E. F . , and S h e r r i l l , J . D . , " P r e d i c t i o n o f Magnitudes and Frequencies of Floods i n Michigan," Report t o Michigan Department of S t a t e Highways and U.S. Bureau of P u b l i c Roads, 1971.

2. B r a t e r , E. F . , and S h e r r i l l , J . D . , " R a i n f a l l Runoff R e l a t i o n s on Urban and Rural Areas." EPA-67-/2-75-046, U. S. Environmental Pro- t e c t i o n Agency, C i n c i n n a t i , Ohio, May, 1975.

3 . B r a t e r , E. F . , "A Study of Flood Condi t ions Along t h e C l in ton River i n t h e Region Which Inc ludes t h e Western P a r t of Pon t i ac , Waterford Township and West Bloomfield Township,'' The C l i n t o n River Watershed Counci l , March, 1976.

4. Flood P l a i n Informat ion Report on t h e Main R ive r and Main Branch C l i n t o n R ive r i n Macomb County, U . S. Army Corps of Eng inee r s , D e t r o i t D i s t r i c t , August, 1964.

5. Flood P l a i n Informat ion Report on t h e Middle Branch o f t h e C l i n t o n River i n Macomb County, Michigan, U. S. Army Corps of Engineers , D e t r o i t D i s t r i c t , October, 1965.

6 . Flood P l a i n Informat ion Report on t h e North Branch o f t h e C l i n t o n River i n Macomb County, Michigan, U. S. Army Corps of Engineers , D e t r o i t D i s t r i c t .

7. Red Run Dra in and Lower C l i n t o n River Flood Con t ro l P r o j e c t , Phase 1 Genera l Design Memoran- dum, Hydrology Appendix, U. S. Army Corps of Engineers , D e t r o i t D i s t r i c t , October, 1977.

8 . HEC-1, Flood Hydrograph Package Users Manual, U. S. Army Corps of Engineers , Hydrologic Engineer ing Cen te r , Davis , C a l i f o r n i a , J anua ry , 1973.

9. R a i n f a l l Frequency A t l a s of t he United S t a t e s fo r Dura t ions froin 30 Minutes t o 24 Hours and Return Pe r iods from 1 t o 100 Years, Techn ica l Paper No. 40 , U . S . Weather Bureau, Washington, D . C . , May, 1961.

10. Gu ide l ines f o r Determining Flood Flow Frequency, B u l l e t i n No. 17 of t h e Hydrology Committee, U . S. Water Resources Counci l , March, 1976.

11. HEC-2, Water Su r face P r o f i l e s - Users Manual, U.S. Army Corps of Engineers , Hydrologic En- g i n e e r i n g Cen te r , Davis , C a l i f o r n i a , December 19'78.

12. Gundlach, D.L., "Adjustment of Peak Discharge Ra te s f o r Urbaniza t ion ," J o u r n a l of t h e I r - r i g a t i o n and Drainage Div i s ion , Proceedings o f t h e American S o c i e t y of C i v i l Engineers , Vol. 104, No. IR3, September, 1978.

Technical Paper Series TP-1 Use of Interrelated Records to Simulate Streamflow TP-2 Optimization Techniques for Hydrologic

Engineering TP-3 Methods of Determination of Safe Yield and

Compensation Water from Storage Reservoirs TP-4 Functional Evaluation of a Water Resources System TP-5 Streamflow Synthesis for Ungaged Rivers TP-6 Simulation of Daily Streamflow TP-7 Pilot Study for Storage Requirements for Low Flow

Augmentation TP-8 Worth of Streamflow Data for Project Design - A

Pilot Study TP-9 Economic Evaluation of Reservoir System

Accomplishments TP-10 Hydrologic Simulation in Water-Yield Analysis TP-11 Survey of Programs for Water Surface Profiles TP-12 Hypothetical Flood Computation for a Stream

System TP-13 Maximum Utilization of Scarce Data in Hydrologic

Design TP-14 Techniques for Evaluating Long-Tem Reservoir

Yields TP-15 Hydrostatistics - Principles of Application TP-16 A Hydrologic Water Resource System Modeling

Techniques TP-17 Hydrologic Engineering Techniques for Regional

Water Resources Planning TP-18 Estimating Monthly Streamflows Within a Region TP-19 Suspended Sediment Discharge in Streams TP-20 Computer Determination of Flow Through Bridges TP-21 An Approach to Reservoir Temperature Analysis TP-22 A Finite Difference Methods of Analyzing Liquid

Flow in Variably Saturated Porous Media TP-23 Uses of Simulation in River Basin Planning TP-24 Hydroelectric Power Analysis in Reservoir Systems TP-25 Status of Water Resource System Analysis TP-26 System Relationships for Panama Canal Water

Supply TP-27 System Analysis of the Panama Canal Water

Supply TP-28 Digital Simulation of an Existing Water Resources

System TP-29 Computer Application in Continuing Education TP-30 Drought Severity and Water Supply Dependability TP-31 Development of System Operation Rules for an

Existing System by Simulation TP-32 Alternative Approaches to Water Resources System

Simulation TP-33 System Simulation of Integrated Use of

Hydroelectric and Thermal Power Generation TP-34 Optimizing flood Control Allocation for a

Multipurpose Reservoir TP-35 Computer Models for Rainfall-Runoff and River

Hydraulic Analysis TP-36 Evaluation of Drought Effects at Lake Atitlan TP-37 Downstream Effects of the Levee Overtopping at

Wilkes-Barre, PA, During Tropical Storm Agnes TP-38 Water Quality Evaluation of Aquatic Systems

TP-39 A Method for Analyzing Effects of Dam Failures in Design Studies

TP-40 Storm Drainage and Urban Region Flood Control Planning

TP-41 HEC-5C, A Simulation Model for System Formulation and Evaluation

TP-42 Optimal Sizing of Urban Flood Control Systems TP-43 Hydrologic and Economic Simulation of Flood

Control Aspects of Water Resources Systems TP-44 Sizing Flood Control Reservoir Systems by System

Analysis TP-45 Techniques for Real-Time Operation of Flood

Control Reservoirs in the Merrimack River Basin TP-46 Spatial Data Analysis of Nonstructural Measures TP-47 Comprehensive Flood Plain Studies Using Spatial

Data Management Techniques TP-48 Direct Runoff Hydrograph Parameters Versus

Urbanization TP-49 Experience of HEC in Disseminating Information

on Hydrological Models TP-50 Effects of Dam Removal: An Approach to

Sedimentation TP-51 Design of Flood Control Improvements by Systems

Analysis: A Case Study TP-52 Potential Use of Digital Computer Ground Water

Models TP-53 Development of Generalized Free Surface Flow

Models Using Finite Element Techniques TP-54 Adjustment of Peak Discharge Rates for

Urbanization TP-55 The Development and Servicing of Spatial Data

Management Techniques in the Corps of Engineers TP-56 Experiences of the Hydrologic Engineering Center

in Maintaining Widely Used Hydrologic and Water Resource Computer Models

TP-57 Flood Damage Assessments Using Spatial Data Management Techniques

TP-58 A Model for Evaluating Runoff-Quality in Metropolitan Master Planning

TP-59 Testing of Several Runoff Models on an Urban Watershed

TP-60 Operational Simulation of a Reservoir System with Pumped Storage

TP-61 Technical Factors in Small Hydropower Planning TP-62 Flood Hydrograph and Peak Flow Frequency

Analysis TP-63 HEC Contribution to Reservoir System Operation TP-64 Determining Peak-Discharge Frequencies in an

Urbanizing Watershed: A Case Study TP-65 Feasibility Analysis in Small Hydropower Planning TP-66 Reservoir Storage Determination by Computer

Simulation of Flood Control and Conservation Systems

TP-67 Hydrologic Land Use Classification Using LANDSAT

TP-68 Interactive Nonstructural Flood-Control Planning TP-69 Critical Water Surface by Minimum Specific

Energy Using the Parabolic Method

TP-70 Corps of Engineers Experience with Automatic Calibration of a Precipitation-Runoff Model

TP-71 Determination of Land Use from Satellite Imagery for Input to Hydrologic Models

TP-72 Application of the Finite Element Method to Vertically Stratified Hydrodynamic Flow and Water Quality

TP-73 Flood Mitigation Planning Using HEC-SAM TP-74 Hydrographs by Single Linear Reservoir Model TP-75 HEC Activities in Reservoir Analysis TP-76 Institutional Support of Water Resource Models TP-77 Investigation of Soil Conservation Service Urban

Hydrology Techniques TP-78 Potential for Increasing the Output of Existing

Hydroelectric Plants TP-79 Potential Energy and Capacity Gains from Flood

Control Storage Reallocation at Existing U.S. Hydropower Reservoirs

TP-80 Use of Non-Sequential Techniques in the Analysis of Power Potential at Storage Projects

TP-81 Data Management Systems of Water Resources Planning

TP-82 The New HEC-1 Flood Hydrograph Package TP-83 River and Reservoir Systems Water Quality

Modeling Capability TP-84 Generalized Real-Time Flood Control System

Model TP-85 Operation Policy Analysis: Sam Rayburn

Reservoir TP-86 Training the Practitioner: The Hydrologic

Engineering Center Program TP-87 Documentation Needs for Water Resources Models TP-88 Reservoir System Regulation for Water Quality

Control TP-89 A Software System to Aid in Making Real-Time

Water Control Decisions TP-90 Calibration, Verification and Application of a Two-

Dimensional Flow Model TP-91 HEC Software Development and Support TP-92 Hydrologic Engineering Center Planning Models TP-93 Flood Routing Through a Flat, Complex Flood

Plain Using a One-Dimensional Unsteady Flow Computer Program

TP-94 Dredged-Material Disposal Management Model TP-95 Infiltration and Soil Moisture Redistribution in

HEC-1 TP-96 The Hydrologic Engineering Center Experience in

Nonstructural Planning TP-97 Prediction of the Effects of a Flood Control Project

on a Meandering Stream TP-98 Evolution in Computer Programs Causes Evolution

in Training Needs: The Hydrologic Engineering Center Experience

TP-99 Reservoir System Analysis for Water Quality TP-100 Probable Maximum Flood Estimation - Eastern

United States TP-101 Use of Computer Program HEC-5 for Water Supply

Analysis TP-102 Role of Calibration in the Application of HEC-6 TP-103 Engineering and Economic Considerations in

Formulating TP-104 Modeling Water Resources Systems for Water

Quality

TP-105 Use of a Two-Dimensional Flow Model to Quantify Aquatic Habitat

TP-106 Flood-Runoff Forecasting with HEC-1F TP-107 Dredged-Material Disposal System Capacity

Expansion TP-108 Role of Small Computers in Two-Dimensional

Flow Modeling TP-109 One-Dimensional Model for Mud Flows TP-110 Subdivision Froude Number TP-111 HEC-5Q: System Water Quality Modeling TP-112 New Developments in HEC Programs for Flood

Control TP-113 Modeling and Managing Water Resource Systems

for Water Quality TP-114 Accuracy of Computer Water Surface Profiles -

Executive Summary TP-115 Application of Spatial-Data Management

Techniques in Corps Planning TP-116 The HEC's Activities in Watershed Modeling TP-117 HEC-1 and HEC-2 Applications on the

Microcomputer TP-118 Real-Time Snow Simulation Model for the

Monongahela River Basin TP-119 Multi-Purpose, Multi-Reservoir Simulation on a PC TP-120 Technology Transfer of Corps' Hydrologic Models TP-121 Development, Calibration and Application of

Runoff Forecasting Models for the Allegheny River Basin

TP-122 The Estimation of Rainfall for Flood Forecasting Using Radar and Rain Gage Data

TP-123 Developing and Managing a Comprehensive Reservoir Analysis Model

TP-124 Review of U.S. Army corps of Engineering Involvement With Alluvial Fan Flooding Problems

TP-125 An Integrated Software Package for Flood Damage Analysis

TP-126 The Value and Depreciation of Existing Facilities: The Case of Reservoirs

TP-127 Floodplain-Management Plan Enumeration TP-128 Two-Dimensional Floodplain Modeling TP-129 Status and New Capabilities of Computer Program

HEC-6: "Scour and Deposition in Rivers and Reservoirs"

TP-130 Estimating Sediment Delivery and Yield on Alluvial Fans

TP-131 Hydrologic Aspects of Flood Warning - Preparedness Programs

TP-132 Twenty-five Years of Developing, Distributing, and Supporting Hydrologic Engineering Computer Programs

TP-133 Predicting Deposition Patterns in Small Basins TP-134 Annual Extreme Lake Elevations by Total

Probability Theorem TP-135 A Muskingum-Cunge Channel Flow Routing

Method for Drainage Networks TP-136 Prescriptive Reservoir System Analysis Model -

Missouri River System Application TP-137 A Generalized Simulation Model for Reservoir

System Analysis TP-138 The HEC NexGen Software Development Project TP-139 Issues for Applications Developers TP-140 HEC-2 Water Surface Profiles Program TP-141 HEC Models for Urban Hydrologic Analysis

TP-142 Systems Analysis Applications at the Hydrologic Engineering Center

TP-143 Runoff Prediction Uncertainty for Ungauged Agricultural Watersheds

TP-144 Review of GIS Applications in Hydrologic Modeling

TP-145 Application of Rainfall-Runoff Simulation for Flood Forecasting

TP-146 Application of the HEC Prescriptive Reservoir Model in the Columbia River Systems

TP-147 HEC River Analysis System (HEC-RAS) TP-148 HEC-6: Reservoir Sediment Control Applications TP-149 The Hydrologic Modeling System (HEC-HMS):

Design and Development Issues TP-150 The HEC Hydrologic Modeling System TP-151 Bridge Hydraulic Analysis with HEC-RAS TP-152 Use of Land Surface Erosion Techniques with

Stream Channel Sediment Models

TP-153 Risk-Based Analysis for Corps Flood Project Studies - A Status Report

TP-154 Modeling Water-Resource Systems for Water Quality Management

TP-155 Runoff simulation Using Radar Rainfall Data TP-156 Status of HEC Next Generation Software

Development TP-157 Unsteady Flow Model for Forecasting Missouri and

Mississippi Rivers TP-158 Corps Water Management System (CWMS) TP-159 Some History and Hydrology of the Panama Canal TP-160 Application of Risk-Based Analysis to Planning

Reservoir and Levee Flood Damage Reduction Systems

TP-161 Corps Water Management System - Capabilities and Implementation Status