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The COMPUTE TRAVEL TIME command is used to compute the normal flow travel time relationship used in ROUTE. The input data aze storage location number, reach identification number, number of valley sections in the reach, reach length, and slope. The reach identification number can be any number from 0.1 to 999.9. The maximum number of valley sections per reach is six. The slope can be either the channel or flood-plain slope or a weighted average of the two. If flow is confined to the channel, the channel slope is of course applicable. If most of the flow is in the flood plain, usually the flood-plain slope is used. However, a weighted slope based on the relative rates of flow in the channel and the flood plain may be used. The COMPUTE TRAVEL TIME command considers each rating curve in the reach in computing the travel time flow relationship. COMPUTE TRAVEL TIME automatically selecis the flow rates that aze used in computing individual travel times. The flow rates of the rating curve with the lowest maximum flow rate aze chosen. If the flow rates of any other rating curve in the reach were chosen, the rating curve with the lowest. rnaximum flow rate would have to be extrapolated. The travel time table is limited to 19 points because of the 20-point limit for rating curves. The STORE TRAVEL TIME command is one of the two computer-punched commands. When the punch code is a positive number, the output from COMPUTE TRAVEL TIME is punched on cards with the STORE TRAVEL TIME com- mand. Therefore, it is not necessary to re- compute rating curves or travel time for future routings. Instead, STORE TRAVEL TIME reads the previously computed travel time flow rela- tionship into the program, thus saving consider- able computer time. The input data for STORE TRAVEL TIME are not punched manually, but a list of data items may be helpful in checking computer- ptmched cazds. The input data aze storage location number, reach identification number, reach length, slope, and individual points of the relationship defined by depth, flow, and travel time. The ROUTE command is used to route floods through streams and valleys. The input data aze storage location number and hydrograph identi• fication number of the outflow hydrograph, storage location number of the inflow hydro- graph, and time increment. The storage location number of the outflow hydrograph must be the same as the storage location number used in COMPUTE TRAVEL TIME for the reach. To prevent unnecessary program stoppage, ROUTE extrapolates the travel-time table when it is exceeded and writes the message, "TRAVEL TIME TABLE EXCEEDED." The ROUTE RESERVOIR command is used to route floods through reservoirs. The input data aze storage location number and hydro- graph identification number of the outflow hydrograph, storage location number of the inflow hydrograph, and individual points of the reservoir's outflow storage relationship. The out- flow-storage relationship must be expressed in 20 points or less. If the outflow-storage relation- ship is exceeded, ROUTE RESERVOIR will extrapolate the relationship and write the mes- sage, "STORAGE-DISCHARGE TABLE EX- CEEDED." The ERROR ANALYSIS command is used to determine the error standazd deviation and the percentage error in peak flow between any two hydrographs in a HYMO program. These fw~c- tions make ERROR ANALYSIS useful in re- search. The input data aze the storage location numbers of the two hydrographs to be analyzed. The SEDIMENT YIELD command is used to compute the sediment yield at any point in a watershed. Input data required are storage loca- tion number of the hydrograph from the azea, a soils factor, a crop factor, a slope length and gradient factor, and a conservation practice factor (8). The FINISH command is used to end HYMO programs. There aze no data associated with FINISH. EXAMPLE HYMO PP.OORAM • i • A short example problem is presented to Riesel, Tex. A flood will be routed t'7rough the • demonstrate HYMO. Figure 4 is a map of the watershed in its present condition, and the `.. 6.84-squaze-mile Brushy Creek watershed neaz routed outflow hydrograph will be compazed to 7-6-1-9