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INTRODUCTION . The runoff response of a drainage basin on precipitation is influenced by the nature of the event, the basin's physi- cal structure, configuration, topogra- phy, geological foundation, soil condi- tions and the amount and kind of vege- tation cover. Land development and u[- banisation have usually a minor effect upon an area's basic topography or geo- logical base. However, man's impact on land surfaces, top soil, vegetation cover, and hence the hydrological re- gime, is nowhere more intensive than in urban areas (Bryan, 1972; IUD Subgroup (UNESCO), 1974). The massive increase in urbanisation expected during the next several decades cl~arly implies that present problems are likely to be compounded alarmingly. . Research on urban water resources has legged behind large catchment research in nearly every nation, is complex, time consuming, and requires a consid- erable financial commitment. Moreover, many more types of hydrological prob- lems will be found in densely populated regions than in rural areas. Most of the urban hydrological problems and ef- fects in developing countries are simi- lar to those in technologically and economically advanced countries. Further, many problems now confronting the developing nations have at one time or another been encountered by the more developed nations (UNESCO, 1976). . A brief .state-of-the-art- summary on the hydrological consequences of urban development is therefore now appropri- ate, and is accompanied by a extensive annotated bibliography for the periOd to OctOber 1978. . Of the thousands of refer~nces which have been published in the liquid wa~te and pollution field. the list qiven here is judged to contain information useful to the planner and other profes- sionals involved in researcn on urban land use and its effects on water quan- tity or quality. Several very good but obscure sources have been omitted, as have detailed lists of peripheral as- pects such as sewa9~ disposal, waste water treatment, tip leachates and ground water pollution these have been the theme of extensive bibliogra- phies elsewhere and need not be repeat- ed, thouqh some suggestions for retri- eval are given. . Many items on specific topics come from a few sources, but the major sources of information for this study wete Journal of the Hydraulics Division ASCE, Envi- ronmental Health and Pollution Control, EPA Reports, Journal of the WPCF, Water Research, Water Resources Research, Water Resources Bulletin, Journal of Hydrology, USGS Professional and water Supply Papers, Water pOllution Control Journal, and the numerous conference proceedings produced by organisations such as the American Society of Civil Engineers, American Public works Asso- ciation, US Public Health Service, Water Pollution Control Federation and other educational institutions. More immediate sources of material are pob- liahed in Pollution Abstracts, Water Pollution Abstracts, Geo Abstracts, Se- lected Water Resou~ces Abstracts, Water << Research Centre Information, and in the irregular annotated bibliographies pro- duced by the Council of Planning Li- brarians and by various US Government Agencies. HYDROUlGICAL EFFECTS OF URBAN DEVE LOPMENT Many reports ~ich deal with the ef- fects of urban development on stream- flow have been published in recent yearsa These effects are summarised by Coughlin and H,mmer (1973) as:- (a) increases in peak flow magnitude and frequency of flooding due to rendering of land impervious and altering of the drainage systems~ (b) possible reduction of baseflow of the stream in periods of low rain- fall due to decreased infiltration to ground water storage~ and (cl enlargement and degradation of stream channels due to changes in the strea~flow regimen identified in (a) above. In more detail, Waugh (1978) and Schou- ten (1979) list the important Quantita- tive effects reported in the literature as:- 1. Severing a rural basin can increase the mean annual flood by almost two times. 2. With about 15 percent of the catch- ment as sealed surface, the mean annual flood peak is at least dou- bled. When the urban basin is 25 percent impervious, the five-year flood may be equal to a 40-year flood for an equivalent rural catchment. 3* A fully impervious basin completely severed and with channels re~liqned can lead to an eiqht-fold increase in flood peak discharge for small floods of around mean annual size. 4* Floods with a return period of 100 years may be doubled in size by complete urbanisation of a catch- ment, if development results in at least a 30 percent paving of the basin. s. Floods beyond the lea-year flood show a relatively lesser effect fro. urbanisation, and a 159-year flood is not materially affected. 6. For, catchment which is 29 percent sewered and 20 percent impervious, tbe number of bank overflows may double. 7. In a completely sewered basin, or for a 58 percent impervious catch- ment, lag time to flood peak can reduce to about 10 percent of that in an equivalent rural catchment. Tbe qteatest change in lag time oc- curs as the basin develops from rural to 20 percent impervious. An important effect of this reduction on basin lag time is that it makes Short-duration high-intensity rain- falls the critical flood-producing storats*