EPHEMERAL FLOW MODELING IN ARID REGIONS

Flow hydrographs in arid upland basins, where the runoff is directly r elated to the rainfall, are simulated by a combination of regression a nd differential equation techniques. The rising limb of the hydrograph is modelled through a regression analysis and the recession portion t hrough a conceptual analog of discharge from a single leaky reservoir, which is described by a continuity equation and by discharge-stage an d storage-stage relations at the basin outlet. A good agreement betwee n observed and model-predicted recession curves was obtained by optimi zing the reservoir leakage rate and the initial storage in the reservo ir. Best parameter values are physically realistic and best reservoir configuration has leakage that varies as the cube of stage for the ini tial event of the season in the organised stream network and as the sq uare of the stage for rest of the events. The technique can be applied to the ungauged flow events through parameterization. (C) 1996 Academ ic Press Limited