Abstract
New attempt of ensemble rainfall-runoff prediction is presented with radar rainfall prediction and spatial random error field simulation. A radar image extrapolation model gives deterministic rainfall predictions, and its prediction error structure is analyzed by comparing with the observed rainfall fields. With the analyzed error characteristics, spatial random error fields are simulated using covariance matrix decomposition method. The simulated random error fields successfully keep the analyzed error structure and improve the accuracy of the deterministic rainfall predictions; then the random error fields with the deterministic fields are given to a distributed hydrologic model to achieve an ensemble runoff prediction.