Technical papers in hydrology 15

Technical papers in hydrology 15

In this series

1 Perennial Ice and S n o w Masses. A Guide for Compila- tion and Assemblage of Data for a World Inventory.

2 Seasonal S n o w Cover. A Guide for Measurement, Compilation and Assemblage of Data.

3 Variations of Existing Glaciers. A Guide to Inter- national Practices for their Measurement.

4 Antarctic Glaciology in the International Hydrological Decade.

5 Combined Heat, Ice and Water Balances at Selected Glacier Basins. A Guide for Compilation and Assem- blage of Data for Glacier Mass Balance Measurements.

6 Textbooks on Hydrology—Analyses and Synoptic Tables of Contents of Selected Textbooks.

7 Scientific Framework of World Water Balance.

X Flood Studies—An International Guide for Collection and Processing of Data.

9 Guide to World Inventory of Sea, Lake, and River Ice.

10 Curricula and Syllabi in Hydrology.

11 Teaching Aids in Hydrology.

12 Ecology of Water Weeds in the Neotropics.

13 The Teaching of Hydrology.

14 Legends for Geohydrochemical M a p s . Legendes des cartes hydrogéochimiques.

Leyenda para mapas geohidroquímicos.

Jlerenna JUIA reorHApoxHMHiec¿HX xapT 15 Research on Urban Hydrology, vol. I.

A contribution to the

International Hydrological Programme

Research

on urban hydrology

Volume I

State-of-the-art reports from Australia, Canada, U . S . S . R . , United Kingdom, U . S . A .

General editor : M . B . McPherson

mnesoo

The designations employed and the presentation of the material do not imply the expression of any opinion what- soever on the part of Unesco concerning the legal status of any country or territory, or of its authorities, or con- cerning the frontiers of any country or territory.

Published in 1977 by the

United Nations Educational, Scientific and Cultural Organization

7, place de Fontenoy, 75700 Paris Printed by Imprimerie Beugnet, Paris I S B N 92-3-101488-9

© Unesco 1977 Printed in France

Preface

T h e 'Technical Papers in Hydrology' series, like the related collection of 'Studies and Reports in Hydrology', w a s started in 1965 w h e n the International Hydrological Decade w a s launched by the General Conference of Unesco at its thirteenth session. T h e aim of this undertaking w a s to promote hydrological science through the development of international co-operation and the training of specia- lists and technicians.

Population growth and industrial and agricultural development are leading to constantly increa- sing demands for water, hence all countries are endeavouring to improve the evaluation of their water resources and to m a k e more rational use of them. T h e I H D w a s instrumental in promoting this general effort. W h e n the Decade ended in 1974, I H D National Committees had been formed in 107 of Unesco's 135 M e m b e r States to carry out national activities and participate in regional and inter- national activities within the I H D programme.

Unesco w a s conscious of the need to continue the efforts initiated during the International Hydrological Decade and, following the recommendations of M e m b e r States, the Organization decided at its seventeenth session to launch a n e w long-term intergovernmental p r o g r a m m e , the International Hydrological P r o g r a m m e (IHP), to follow the decade. T h e basic objectives of the I H P were defined as follows: (a) to provide a scientific framework for the general development of hydro- logical activities; (b) to improve the study of the hydrological cycle and the scientific methodology for the assessment of water resources throughout the world, thus contributing to their rational use;

(c) to evaluate the influence of m a n ' s activities on the water cycle, considered in relation to environ- mental conditions as a whole; (d) to promote the exchange of information on hydrological research and on n e w developments in hydrology; (e) to promote education and training in hydrology; (f) to assist M e m b e r States in the organization and development of their national hydrological activities.

T h e International Hydrological P r o g r a m m e became operational on 1 January 1976 and is to be executed through successive phases of six years' duration. I H P activities are co-ordinated at the international level by an intergovernmental council composed of thirty M e m b e r States. The m e m b e r s are periodically elected by the General Conference and their representatives are chosen by national committees.

The 'Technical Papers in Hydrology' series is intended to provide a means for the exchange of information on hydrological techniques and for the co-ordination of research and data collection.

In order to co-ordinate scientific projects, however, it is essential that data acquisition, transmission and processing be conceived in such a w a y as to permit the comparison of results. In particular, the exchange of information on data collected throughout the world requires standard instruments, tech- niques, units of measurement and terminology.

It is believed that the guides on data collection and compilation in various specific areas of hydrology which have been published in the 'Technical Papers in Hydrology' series have already helped hydrologists to standardize their records of observations and thus have facilitated the study of hydrology on a world-wide basis.

M u c h still remains to be done in this field, however, even as regards the simple measurement of

basic elements such as precipitation, snow cover, soil humidity, run-off, sediment transport and ground-water phenomena.

Unesco therefore intends to continue the publication of 'Technical Papers in Hydrology ' as an indispensable means of bringing together and making k n o w n the experience accumulated by hydro- logists throughout the world.

Contents

Foreword 9 Urban hydrological modelling and catchment research in U . S . A . 11

Section I Introduction 13 Section 2 Urban hydrological modelling 15

Section 3 Urban catchment research 41 Urban hydrological modelling and catchment research in Australia 65

Section I Field research 67 Section 2 Hydrological models 76

Section 3 Applications 80 Section 4 Conclusions 87 Urban hydrological modelling and catchment research in Canada 89

Section 1 Urban catchment research 91 Section 2 Urban hydrological modelling 104 Section 3 S u m m a / y and conclusions 118 Appendix I Selected Canadian urban test catchments and s u m m a r y of urban

run-off field studies of limited scope 125 Appendix II Instrumentation considerations 137

Methods for calculating m a x i m u m flood discharges for natural watercourses and

urban areas in the U . S . S . R . 143 Computation of peak flow 145 Application of precipitation data 145 Use of run-off coefficients 150

Flood travel time 150 Flood volumes and flood hydrographs 153

Flood frequency 158 Urban hydrological modelling and catchment research in the United K i n g d o m 161

Section 1 General introduction 163 Section 2 Urban catchment research 165 Section 3 Urban hydrological modelling 179

Foreword

This volume has been prepared under International Hydrological P r o g r a m m e sub-project 7.1, 'Research on Urban Hydrology'. It contains the first five of the national state-of-the-art reports foreseen within the general framework of project 7, 'Effects of Urbanization on the Hydrological Regime and on Quality of Water', adopted by the Intergovernmental Council of the International Hydrological P r o g r a m m e at its 1975 session. T h e project includes also sub-project 7.2, 'Development of Mathematical Models applied to Urban Areas considering both Water Quality and Quantitative Aspects'.

T h e Bureau of the International Council of the International Hydrological P r o g r a m m e appointed M r . M . B . McPherson ( U . S . A . ) as rapporteur of sub-project 7.1 at its first session in August 1975, and defined the tasks to be carried out under the sub-project as follows:

1. T o prepare 'state-of-the-art' reports reviewing current research on urban hydrology based on case studies; the reports are to include descriptions of laboratory and field studies, instrumentation, methods of processing and analysing information from experiments, development of models on urban water systems and urban planning, water quantity and quality processes, etc.;

2. T o prepare outlines of the information manuals on urban water data collection, analysis and use.

This endeavour originated from activities and aspirations of the Unesco Subgroup on the Hydro- logical Effects of Urbanization of the International Hydrological Decade. Part I of the Subgroup final report1 entitled 'International S u m m a r y ' , was resolved by representatives of over thirty nations w h o participated in an International W o r s h o p at W a r s a w , Poland, N o v e m b e r 19731 at which ten crucial international research projects were proposed for inclusion in the Unesco component of the International Hydrological P r o g r a m m e .

T h e American Society of Civil Engineers ( A S C E ) took early supportive action by applying for an N S F grant to assist in two of the ten recommended projects: R . l . Catchment Studies Report, and R . 3 . Mathematical Models Report. In April 1975, the International Council for the I H P adopted I H P Project 7, which includes the two subjects in question and thus m a d e it possible for Unesco and the A S C E to co-operate closely on the state-of-the-art reports.

O f particular significance was the very strong emphasis of the W a r s a w W o r k s h o p and the Sub- group on the urgency of addressing all such reports to users of research findings. That is, an accentua- tion of user participation and user orientation of I H P urban products clearly indicated that facili- tation of the translation of research findings into implementation practice should be a central goal.

In most countries, economic growth, population growth, non-agricultural water use and pollu- tion are intertwined. Water in its m a n y manifestations plays a vital role in the extremely complex processes of urbanization, and thus affects a nation's health and growth. T h e most significant con- clusion reached by the I H D / U n e s c o Subgroup is that most urban hydrological problems and effects are similar in technologically and economically advanced countries. Further, m a n y problems confron- ting the developing nations have at one time or another already been encountered by m a n y deve-

9

loped nations. This strongly suggests that great benefits would result from the exchange of infor- mation and increased international co-operation in research and development.

T h e report for the U . S . A . served as the prototype for the series of national reports, and w a s circulated to experts in other countries for the purpose of obtaining analogous contributions.

Unesco wishes to thank the authors for assembling the reports presented in this volume, which should facilitate international communication on the state of the art in urban hydrology. Additional volumes will be issued in the future, as further contributions to sub-project 7.1.

References

1. Unesco, HydrologicalEffects of Urbanization, Paris, Unesco, 1974, 280 p. (Studies and Reports in Hydrology 18).

2. A S C E , 'Report, International Workshop on the Hydrological Effects of Urbanization, Warsaw, 1973'. N e w York, N . Y . , N S F , January 1974, 61 p.

10

Urban hydrological modelling and catchment research in U . S . A .

M . B . M c P h e r s o n

American Society of Civil Engineers 345 East 47th Street

N e w York, N . Y . 10017, U . S . A .

Section 1 Introduction

Scope of This Report

In keeping with the findings of the Subgroup and the Warsaw Workshop, modeling and catchment research for urban drainage systems is emphasized. This is the subject singled out as having the largest gaps in knowledge in urban hydrology.

Water quality aspects are accorded considerable attention because of the strong interest in environmental protection in the U.S. The issue has been succinctly stated: "When a city takes a bath, what do you do with the dirty w a t e r ? " ^ ' Precipitation removes considerable amounts of particulates from urban areas. As an indication of the extent of this potential burden, it has been estimated that the 330-km' of the City of Philadelphia, with a population of two million people, typically produces, in metric tons: 2,900-tons/day of pollution emissions;

780,000-tons/year of trash; 82,000-tons/year of garbage; 560,000-tons/year of incinerator residue; 24,000-tons/year of debris from inlets; and 83,000-tons/year of street sweepings.'^' In addition: Philadelphia replaces 30-kra to 40-km of asphalt paving per year; surfaces collect the wear from four million pair of

shoes; there is erosion from the 650,000 buildings in the City; the 250,000 animals contribute their droppings; there is erosion from over two million vehicle tires;

e t c . ^ ' A large share of these numerous residuals is washed away from the land surface and is transported to receiving bodies of water. This is over and above the contributions from municipal and industrial wastewater treatment plant effluents.

Figure l'5' is a simplified description of the stormwater and wastewater portion of the urban water resource system. This report emphasizes the quantity and quality aspects of the stormwater subsystem therein, described in Figure 1, Section 2.

References

1. Field, Richard, and John A. Lager, "Urban Runoff Pollution Control - State- of-the-Art." J.Envir.EngrR.Div., ASCE P r o c , Vol. 101, No. EE1, pp. 107-125, February, 1975.

2. Radziul, Joseph V., "City Pollution Loading Potential," pp. 12-13, Urban Runoff. Quantity and Quality, ASCE, New York, N.Y., 1975.

3. Sonnen, M. B., Larry A. Roesner and Robert P. Shubinski, "Urban Water Management Models," pp. 89-97, Urban Runoff. Quantity and Quality, ASCE, New York, N.Y., 1975.

13

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Section 2 Urban hydrological modelling

Introduction

Shown schematically in Figure l'1' is a simplified description of the major components of the urban stormwater disposal sub-system.

Natural watercourses occupy much less land area than that drained directly by systems of underground drainage conduits. It has been estimated that approximately one-sixth of U.S. "Urban Areas" (measure of metropolitan areas adopted for the 1970 Census) fall within natural 100-year flood plains,^2' whereas well over half of Urban Areas are drained by system's of underground conduits. Further, national

investment for storm drainage conduit facilities appears to be more than four times as great as that for flood plain protection works benefiting urban areas.

There is widespread interest in multi-purpose drainage facilities that exploit opportunities for water-based recreation, provide more effective protection of buildings from flooding, and allow for the use and re-use of storm water for

water supply. In addition, the 1972 Amendments to the Federal Water Pollution Control Act, which established a national goal of zero-pollution, has led to considerable

interest in reducing the entry of pollutants into receiving waters from combined sewer overflows and storm sewer discharges. All these emerging requirements call for the use of storage facilities and special treatment works, together with some kind of control system able to manage the sudden and brief impact of stormwater. In sum, over the last few years urban model development has greatly intensified, with sewered catchment models perhaps eclipsing urban receiving-water model development.

Because of this and of the tendency to use tailor-made or custom-adapted models for urban strearaflow discharge-quality, discussion of models for simulation of under- ground conduit system performance will predominate.

Anticipating the possible future availability of new field data, an ASCE study team in 1968 defined considerations for modeling sewered urban catchment rainfall-runoff-quality processes^-3' and at the same time considerations for characterizing rainfall time and spatial distributions in future research were explored.^'

Space does not permit presentation of a more comprehensive background, and the reader is referred to a previous summary for a much broader coverage.^-*' Also, problems in modeling urban catchments have been discussed elsewhere,(°) and

findings have been reported of a general study of stormwater detention usage in the U.S.A.''' Eight lectures on urban runoff given at a training course are in- cluded in a report'"' that is suitable for use as a text or manual in addition to its value as a unique information source.

*: Numbered references are cited at the end of this Section. Sections 2 and 3 have been made as self-contained as possible, with their own reference lists. As a result, there is some duplication. The phrase "available from NTIS" in a number of entries refers to the National Technical Information Service, U.S. Department of Commerce, Springfield, Virginia 22151, from which reprints are available for a cost-recovery charge.

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Types of Models

Mathematical models used for the simulation of urban rainfall-runoff or rainfall-runoff-quality can be divided into three distinct categories: planning models, design/analysis models and operations models.

Planning Models are used in macro-scale applications, such as for metropolitan or city-wide master plans. As an example of the scale encountered, the City of Milwaukee has 2,200-km of separate storm drains and combined sewers within the 246-kra2 of the City,^*' and these conduits are distributed over 465 drainage catchments having a maximum size of 740-ha and a median size of 1 0 - h a . ^ ^ ' When dealing with so many components the model used must be as simple and as flexible as possible. That is, data processing for planning applications becomes a much more important practical consideration than the level of sophistication of hydrological process modeling.

Design/Analysis Models are hydraulically more sophisticated and thus are more detailed tools. They are used for analyzing individual catchments and sub- catchments where the simulation of detailed performance of discrete elements within a subcatchment must be achieved. Whereas hourly rainfall data is an appropriate input for planning models and for simulating flows in larger urban streams, 5-minute interval rainfall data (the shortest duration reported by the U.S. Weather Service) is the appropriate input for simulating flows in sewers and small urban streams for design applications. That is, the level of sophistication of hydrological process modeling for design becomes a much more important practical consideration than data processing, just the opposite of the emphasis imposed by planning requirements.

Operations Models are likely to be more application-specific than planning or design models because of wide diversities in management practices, operating problems and individual service-system configurations. However, the most potentially transferable technology will be for complete, "hands-off" automatic operational control of total community runoff, a capability that probably will not be reached for several years.v1 1' The mathematical models required are control algorithms, which will have to be painstakingly derived from numerous indicator applications of both detailed design models (for generalization of the performance of individual components by simulation) and planning models (for generalization of community-wide system performance by simulation). Here also, design/analysis models are used as tactical tools and planning models are used as tools of strategy.

Sewered Catchment Models

In keeping with the unanimous recommendation of the IHD/Unesco Subgroup on the Effects of Urbanization on the Hydrological Environment that state-of-the- art reports, including the present one, "should be addressed to users of research findings,"'12' only those models that have been tested against actual field data will be discussed. Table 1 lists 16 models and identifies and describes the catchments that were the source of field data which was used in their testing.

Table 1A lists the source references for Table 1 entries.

Explanation of Table 1 Entries. Instances where more than one model was tested by a given organization against data from one or more catchments are entered as capital letters above the diagonal indicating an entry. Singli nodel tente by * given organization againat data from on« or more catchmenta ara enterad as lower-cage letters below the diagonal indicating an entry, for each source

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reference involved. For the latter, instances where water quality (biochemical) parameters were also tested with the models are indicated by an underline of the identifying letter. Two Australian catchments and one Canadian catchment are included at the bottom of Table 1 because data from them was used in testing U.S.- developed models. Entries are not of equal validity because a few involved perhaps three dozen storm events whereas some involved only one or two. Entries were restricted to cases where a report describing the tests was available to

the public. "Total Imperviousness, Per Cent," is listed to give the reader some indication of the extent of urbanization; and the percentage may have changed over the period of record available, but the latest estimate has been entered in Table 1.

Comments on Table 1 Entries. Of considerable importance are the facts that: in almost every instance field flow measurements have been made only at one location; over half of the flow measurements have been indirect via stage gages, only a part of which have been related to the characteristics of downstream hydraulic controls, with the remainder depending on assumed conduit friction coefficients; and on less than half of the catchments water quality data has been collected, and only for a fraction of these has such data been used in model tests.

The first 14 models cited are of the analysis/design type, and all fit a distributed classification because they take into account sub-catchment physical characteristics in some way, and most accommodate underground conduit transport hydraulics. On the other hand, "STORM" is a planning model and does not have any transport

reckoning capability. Unit hydrograph entries are included only where this method was one of several tested by a given organization; and some other applications will be discussed subsequently. Greater frequency of tests on particular catch- ments is not accidental and can be credited to the ASCE Urban Water Resources Research Program for rescuing and reporting field data for the Northwood,(13) Oakdale,^ ' Grey Havení1^) ancj Boneyardí-*-5^ catchments, together with details on physical catchment characteristics suitable for modeling. Other catchment

descriptions and/or data compilations not cited in Table 1A include: a series of reports'1'' for Castro Valley, Strong Ranch and Ross and Peralta Creeks in

California; papers^1 8'1 9^ on water quality data for the Durham, N.C., catchment;

details on the Mt. Washington (Cincinnati) catchment;(20) data on the seven Seattle, Washington, catchments;(^1) and data displays for the Baker Street, San Francisco, catchment.(•*

Availability of Computer Programs

Illinois Urban Drainage Area Simulator. Entered in Table 1 is the testing record for a U.S. adaptation of the British Road Research Laboratory method. ILLUDAS utilizes the directly connected impervious area concept of the RRL method but also recognizes and reproduces runoff from grassed and non-

connected impervious areas. The verification report^3^ includes a user's manual, and the computer program is available to the public. Water quality considerations are not accommodated, and the intended uses of the model are the sizing of conduits and the evaluation of existing underground systems.

Environmental Protection Agency SWMM and Variants. Subroutines for the EPA Storm Water Management Model are represented symbolically in Figure 2.(") A user's manual'^-1' and the computer program are available to the public for the

latest version developed for EPA, by the University of Florida. A user's manual'17/ and the computer program are also available to the public for the version

*: References indicated by letters appear in Table 1A.

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developed for the City of San Francisco by Water Resources Engineers. The

"Runoff" module of the EPA Version I I ^2 3' and the "Transport" module of the SF version are considered to represent significant advances. The "Cost" and

"Receiving Water" modules have not yet been interfaced with the SF version; and it has also been tested on field data from nine catchments in Hamburg, Federal Republic of G e r m a n y . '2^ Three organizations developed jointly the original EPA SWMM, two of which developed the versions noted above. The third, Metcalf and Eddy, Inc., developed a version used by the firm in studies in the Boston area, and in Chicago(v' and Cleveland.(X-J Developed expressly for quantity and quality evaluation of sewered systems, the various versions of SWMM collectively have been subjected to more verification than any other such models. Several catchment tests have included receiving-water simulation, with comparisons of observed and computed water quality parameter magnitudes in the vicinity of outfalls. It is expected that refinement and improvement of the various versions will continue.

University of Cincinnati. Components of the University of Cincinnati model are symbolized in Figure 3.(25) A model description and the computer program are publicly available.(n)

Hydrocomp. The Hydrocomp Simulation Program System, outlined in Figure 4,(26.) fundamentally simulates watershed hydrology and flow routing.(27) The HSP is the commercial successor to the Stanford Watershed Model, first reported in 1960.(28) Several versions of the latter have been developed by others,(29) notably the Kentucky Watershed Model,(30,31) which has been tested using data from several urban streams. The non-proprietary Stanford Watershed Model has been tested against field data for five streams in California in connection with simulations of the effects of changes in urbanization.

(32) However, only the proprietary HSP accommodates water quality considerations, and some metropolitan planning examples will be cited later. A distinctive feature of the HSP and the Stanford Watershed Model is a continuous simulation capability.

Massachusetts Institute of Technology. The general structure of the MIT Catchment Model is shown in Figure 5.(n)Predominantly an analysis/design model, the current computer program is proprietary. However, a modified version developed for estimating sewered catchment and stream runoff for the master plan development of the 1000-km2 County of Fairfax, Virginia,(33) may be made publicly available.

University of Illinois Models. A user's manual with part of the computer program listing is available to the public,(34) and other portions are reported elsewhere.(c'

University of Nebraska. A model description and the computer program listing are publicly available for quantity(k' and quality^6' simulation.

Dorsch Consult. Analogous in complexity and capabilities with SWMM-type models, the Dorsch Hydrograph-Volume-Method models-") ¿s proprietary.

Georgia Institute of Technology. A model description and the computer program listing are publicly available. ( O

Battelle Northwest. A general description of the model has been published but details are in a report to a client.(37) While the model is being utilized in the analysis of existing sewer systems in Cleveland, Ohio,

24