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<br />HEC-l INPUT DESCRIPTION <br />BASm RUNOFF DATA (B Cards) <br /> <br />6.2 BF CARD - BASE FLOW CHARACTERISTICS <br /> <br />Base flow parameters (STRTQ, QRCSN, and RTIOR) will be assumed equal <br />to zero unless this card is supplied. Once this card is supplied, all <br />following subbasins will be assumed to have these values unless overriden <br />by another BF card. <br /> <br />FIELD VARIABLE VALUE DESCRIPTION .. <br />Col 1+2 ID BF Card identification. <br />1 STRTQ + Flow at start of storm in cfs (cu'ls). <br /> Will be receded in same manner as QRCSN <br /> below. <br /> <br />2 <br /> <br />QRCSN <br /> <br />+ <br /> <br />When negative, this is cfs/sq mi <br />(eu m/s/sq km) which ~.i;],J..15",~ltiplied by <br />subbasin area, TAREA, tQ.4'~,,!II!ne 'STRTQ. <br />"'.;;': .r.:}~5!,~_,:_:i ":"'/~'~~"-':"ii - . <br />Flow in cfs (eu m/s) beloW'wtlieh baSe fl_ <br />recession occurs in accordance with tftl <br />recession constant RTIOR. QRCSN is that <br />flow where the straight line (in semilQ9 <br />paper) recession deviates from. the falling <br />limb of the hydrograph. <br /> <br />3 <br /> <br />RTIOR <br /> <br />+ <br /> <br />f-!ri:,,;" <br />When negative, it is the ratio'bY'which the <br />peak discharge is multiplied to compute <br />QRCSN. <br /> <br />Ratio of recessioD'~low, QR<$N~o ~hat flow <br />occurring one tibfig:.:.~. '. Must be greater <br />than or equal tol'.' . <br /> <br />,,: <br />NOTE - The definition of RTIOR has been changed from tbe~loUl ' version <br />of HEC-l. The old value is QA/QB in the following equatioir:::, . <br />,,}. <br /> <br />New RTIOR = (QA/QB) ** (l/DT) <br /> <br />. <br /> <br />Where QB is a recession flow occurring DT hours after recession fl~QA. <br /> <br />~ <br /> <br />Page 22 <br />