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• (~ • the computed and stored hydrographs on cazds; it is therefore not necessary to recompute hydrographs for future routings. Instead, the previously computed hydrographs are read into the program, thus saving considerable computer time. Although the input data for the RECALL HYD command aze never punched manually, a list of the data items may be helpful in checking computer-punched cazds. The input data aze storage location number, hydrograph identifica- tion number, time increment, drainage azea, peak flow rate, runoff volume, number of hydrograph points, and flow rates of the hydro- graPh. The PRINT HYD command is used to print coordinates of a hydrograph, volume of runoff, and peak flow rate. The required input data are the storage location number and apeak-volume code. The peak-volume code is deleted if a complete hydrograph printout is desired. If a printout of only the runoff volume and the peak flow rate is needed, the peak-volume code is set to a positive value. The PUNCH HYD command is used to punch any hydrograph in a HYMO program in the proper form for 'the RECALL HYD command. PUNCH HYD has two purposes: (1) If the punch code is not used, PUNCH HYD can be used to punch one or more hydrographs for future use; and (2) if it is desirable to punch outflow hydrographs associated with ROUTE, ROUTE RESERVOIR, or ADD HYD, PUNCH HYD must be used because the punch code only provides for punching hydrographs associated with STORE HYD and COMPUTE HYD. The only datum required for PUNCH HYD is the storage location number of the hydrograph to be punched. The PLOT HYD command is used to plot hydrographs in a HYMO program. It will plot one hydrograph on a set of axes, or if a comparison is desired, it will plot two hydro- graphs on the same set of axes. The required input data aze the storage location numbers of the hydrogxaphs to be plotted. The ADD HYD command adds the coordi- nates of any two hydrographs. The hydrographs aze added at a time increment equal to that of the hydrograph with the shorter time increment. The only data required aze the storage locatioh number and hydrograph identification number 7-6-1-5 of the added hydrograph and the storage loca- tion numbers of the two hydrographs to be added. The STORE RATING CURVE command is used to store rating curves that have been measured or computed previously. STORE RATING CURVE will save considerable com- puter time if measured or computed rating curves aze available. The input data aze the storage location number, valley, section number, and individual rating curve points described by elevation, end-area, and flow rate. The number of points used to describe a rating curve is limited to 20. The COMPUTE RATING CURVE command is used to compute the stage-azea-flow relation- ship for a valley section. The input data are storage location number, alley section number, number of segments in the valley section, minimum elevation, maximum elevation, chan- nel and flood-plain slopes, Manning's n value and segment boundary point for each segment, and horizontal and vertical position of points de- scribing the valley section. The storage location numbers of the valley sections in a particulaz reach must begin with 1 and increase by one for each valley section in the reach. However, the numbers aze assigned without regazd to upstream or downstream order. The valley section identification number can be any number from 0.1 to 999.9. These rules concerning storage location and valley section identification numbers also apply to the STORE RATING CURVE command. Normally, valley sections aze divided into three segments (two flood-plain segments and a channel segment) for computing the rating curve. However, some valley sections may have more than one channel or may have an extreme vaziation in n values across the flood plain, thus requiring more than three segments. A maxi- mum of six segments is permitted. Manning's n values for each segment aze input with seg- ment boundary point (distance from the begin- ning of the valley section to the end of the segment). Flood-plain it values aze positive and channel rt values aze negative. Twenty points aze used to define a rating curve. The location of the points is determined by dividing the difference between the maxi- mum and minimum elevations into 19 equal increments.