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Initially a very d~tailed model of the catchments wus Amployed thus providing a fine soatial resolution but at rela- tively high cost. A simpl~ sch~m~ was developed in which th~ netailed model may b~ replac~d by a much cOnrs~r and less expensive mathematical mod~l with no significant loss of accur~cy. , BRAT~R, E.P. 1968: ~Steps towards A better understanding of urban runoff processes~. Water Resources Rosearch, Vol.~(2); p335-47. Key words: urb~nisation; rainfall-runoff relationships; urban drainage. Rainfall and runoff from dr~inaqe ba- sins in various stuges of urbanis0tion were analysed to determine th~ initial retention, the hydrologically siqnifi- c~nt impermeabl~ area. and the inf.il- tration cap0cities of th~ p~rmcablp portions of the basins. The drainage basins, varying in size fro~ 9.5 to 185 square miles. ~rc located in th~ D~tro- it metropolit2n ar~0. Techniqu~s w~re developed th~t largely e1i~in~t~d per- sonal judg~ment in separGting surfuc~ runoff from ground wat~r nisc~ar?p. Infiltrution cQoaciti~s in this region arc from 3 to 5 times hiqh~r in lute summer than in e<!.rly sprinq. The C.ver- age initial retpntjon for th~ b~sins slu1ied is approximately 0.2 inch. The hydrologically significant impermeable ar~a Bppears to be closely rel~ted to the population density, but the effect of other factors is being studi~d. ~n investigation of th~ cause of Season31 and short period v2riations of infil- tration capacity may provide a better understanding of the infiltration pro- cess. BRATER, E.F. et al. 1974: MSeasonal ef- fects in flood synthesis.. Water Re- sources Research, Vol.10(J): p441-445. Kozoy words: flood discharge, stor~ dies; mathematical forecast i ng; pea k runoff; moc'lel stu- models; snowmelt. , The effect of urbQnisation on flood flows is being investigat~d by analys- ing inputs 2nd corres?onding floon hy- drographs from many watersh2ds along with corresponding inputs and r~sponses from watersh",d mod'?ls. Tho: inputs con- sist of orccinit8tion plus snowmelt minus infiltration and retention. Because of th~ large seasonn1 variation in infiltration rates, accuracy was im- proved by treating rainfall frequencies s~usonally in predicting flood runoff from precipitation and snowmelt. As procedures W0re developed and improved in accuracy, it beca~e nec~ssary to ex- amine the effect of snow~elt on winter freauencies and the season3l variation in . time-intensity rainfall patterns more closely. A procedure was devel- oped for including snowm.:-lt with winter rains, and the resulting frequency curves of rain plus snowmelt are pre- sented and compared with conventional rainfall frequ~ncy curv~s. ^ method of deriving time-intensity patt~rns from daily rainfall was developed, and it w~s shown that a large difference ex- ists between typical winter and summer patterns in southeastern Michigan. BRATER, E.F. and SUR8SH S;a.NG^t, 1969: "effects of urb~nisation on peak flows". In, Effpcts of w2ter5he~ changes on streamflow, Section 3, urban watersh~ds (eds. W.t. ~oore~ C.~. Morgan), University of Texas, Austin; p201-214 . Key words: peak discharge~ storm ru- noff; urb~nisation; surface runoff; hydrographs. The authors point out thut the eff~cts of building structures mny ~~ to aggra- vate the flood problem. This is com- poun~ed by th~ evid~nce of increas~0 rainfall in urban ~reas. Ch3nges du~ to urbnnis~tion will be d~~nd~nt on the original state of th~ basin. The need for qu~ntitative means of study of the effects of urbanisation on surf~c~ runoff is str~ssed. One ~poroach is to establish rel?tions betw0~n par~m0t~rs defining the Sh3p~ of th~ unit hydro- qcaDh and some measur~s of b~sin char- act~ristics. preliminary r~sults fro~ 15 basins in the D~troit ar~3 reinforc~ the view that hydroqra~h p0aks 3re en- hanced and the period to rise shortenen with increa~0d urb~nis~tion. BRATER, E.F. and SRERRILL, J.D. 1975: "R~infall-runoff relet ions on urban and rural areas~. Final Report, Michigan University, Ann Arbor, Deet. of Civil Engineering; le8pp. (EPA/670/2-75-046) . K~y words: mathematical hydrographs; peak analytical techniques: relationships. 1\odels; discharge: rainfall-runoff ~ procedure was developed for estim~t- ing the frequ~ncy of storm rur.off of various magnitud~s from r3inf8]1 "nd/or snowmelt on small drainage basins in various staQ~S of urbanis~tion. T~? study WnS "based pri~arily on the n~?- lysis of storm rUnoff ~vpnts on r~~l basins varying in size from ~.~2 to 734 squ~re miles. The method is based on applying unit hydrograohs to precioit~- tions of various freauencies ~fter 0~- ductinQ infiltration and retention. A concurrent study with an analytical drninage basin model provi~0d addition- al understanding of tne effects of som~ par~mcters. The unit hydrograph-infiltration c~o~city con- cept was selecte0 as the most accurate practical method for predicting storm runoff. It was found that the form of the unit hydrograph coul~ be r~lated to drainage basin size and cegree of ur- banisation 3S measured by popul~tion density. Other characteristics of the drainage basin are much less important. BR~HM.ER, M.L. 1972: ~Agricultural and urban pollution~. In, Remote sensing of the Chesapeake Bay, U.S. NA5~, 73-76. U.S. Govt. Printing Office, washinqton, D.C. Contributions of the Virginia Institute of Marine Science, 1971-72, No.468.