interest tliat are less tlian the lowest measured calibration flow should 

 improve over calculations previously made with zf = 0. 



The program should be run using three sets of stage-di scharge data collected 

 at a high, intermediate and low flow. Additional data sets are desirable, but 

 not necessary. The three measurements are made when runoff is receding (high 

 flow), near the end of runoff (intermediate flow) and during late summer-early 

 fall (low flow). The high flow should be considerably less than the bankfull 

 flow, while the low flow should approximate the lowest flow that normally 

 occurs during the summer-fall field season. Sufficient spread between the 

 highest and lowest calibration flows is needed in order for the program to 

 compute a linear, sloping rating curve. 



The WETP program will run using only two sets of stage-discharge data. This 

 practice is not reconmended since substantial "two-point" error can result. 



In addition to wetted perimeter (WETP), the program also predicts other 

 hvdraullc characteristics that can be used in deriving flow recommendations 

 for selected time periods and life I unctions. These are the moan depth (DRAT) 

 in ft, mean velocity CVHAP.) in ft/sec, top width (WDTH) in ft, cross-sectional 

 area (AREA) in ft', stage (STCE) in ft, and maximum depth (DMAX) in ft. 



A useful program option, termed the width-at-given-depth (WAGD) option, will 

 calculate for up to 10 given depths the width (in ft) and percentage of the 

 top width having depths greater than or equal to the given values. The width 

 and percentage of the longest, continuous segment having the required depths 

 is also listed for each flow of interest. This option is illustrated in 

 Appendices B and C. 



