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� wav�.� r�tivw�UK <br /> -- �. Mh►.tuJtt,.. 8 <br /> rntite 2-sa <br /> Ground Caiet CoeLTieienn <br /> Tvoa e!Cover K (�round caver coef5cientl <br /> Foross vrlM heavy ground cnver ISO . <br /> Mlntmum tlUaae cultivstlor 280 <br /> Short paswre grau or Iawn • c20 <br /> Nearly bare grvund 600 <br /> Grawed watetway or rmall roadsida dlteh 900 <br /> Paved area 1,200 <br /> Gutter flo�v 0.23 t•eac deep I,500 <br /> 0.30 Le�tde�p 2,400 <br /> 0.77 E�etCaep ),100 <br /> Contrete CMP <br /> (�a O.OL2) ( v 0.026 <br /> Storm Sewers(Concrete) 12 Inth dlameter 3,000 1�500 <br /> 1! Ineh dlameter 3,900 1�9J0 <br /> I4 lnch diameter 4,700 2�330 <br /> Narrew d <br /> W D� l �.j . 9 <br /> Qpen Channel Flcw(n=0.090) 1 foot da�p 1,100 1�J00 2�000 <br /> 2 feetdaep 1,d00 2,�00 3,100 <br /> 0 ieecdeap 2.b00 ),700 5,000 <br /> 2-3A Rainfalllntetultv <br /> � A. Raln2all inuntiry Chotts <br /> � When Ne time of cancsntrnUon and storin lrequency ara knoWn, tha ninfall ln:enatty ts obtalned trom th� raintall <br /> lntensiry charta at the md oi Nb chepter (Appendlx Z-1). Fieh ehart d�ows tha Intsn�lty o! th� rtlnlall fer lOC-, <br /> 50-� 25-, IO-, and 3-year storm ftaquencles Sor a durotlon oi S to !00 minutes. 1t ls the pract(ce of the WSOOT <br /> Heedquartera Hydraullea 5lctlon to use a minlmum Ume of toncrntrntlon of IIvo minut��. It should be noted that the <br /> ralnfall Intenalty at any gN�n time b Me average from zaro minutes ta Ne tlme eonsldarad and Is not the <br /> Wmntaneous rsintall. <br /> B. RalntaU Intenii:; cqua�'.,n <br /> ln eddltlon to tho r�nul: i-�._c_�y cnnrtz, the designer alsa has the optlon of d¢tarmining raintall data by use of a <br /> mathomaticel equauor.. This equatlon has tho form: <br /> I e �— <br /> rn <br />� whercc m and n = dlmenslonlees CoeifiCienss <br /> T + the miniall duntlon Iminutes) <br /> i I - the averaga minfall lrtansity pnches per huur) , <br />' . ,. MR! - mean recurrence interval <br /> �, :. . <br /> Z _� llay 1959 <br />