Hydrograph Synthesis for Watershed Subzones from Measured Urban Parameters

An analog computer program was developed to simulate the outflow hydrographs at four locations within the 38th Street Waller Creek urban watershed at Austin, Texas. Actual outflow was gaged at the final outlet of the watershed. This provided a checkpoint for comparing the simulated and observed final outflow hydrographs. The outflow hydrographs for each subzone were obtained by chronologically abstracting interception, infiltration, and depression storage from their precipitation hyetographs. These outflow hydrographs were then routed through Waller Creek channel to obtain the hydrographs at the four desired locations. The advantages of this model are the flexibility in varying the precipitation inputs to each subzone and the ability to obtain the contribution to the final flood hydrograph of each subzone.