Selecting reference streamflow forecasts to demonstrate the performance of NWP-forced streamflow forecasts

Abstract

We assess four different reference forecasts for the purpose of measuring the skill of streamflow forecasts generated from Numerical Weather Prediction (NWP) model rainfall forecasts. The reference forecasts we investigate are 1) streamflow climatology, 2) persistence, 3) a hydrological model forced by zero rainfall and 4) a hydrological model forced by an ensemble of resampled historical rainfall. We assess performance of reference forecasts to lead-times of 9 days. Reference forecasts should be simple to produce, but also must be reasonably accurate to establish a robust performance threshold. We show that because streamflows are strongly autocorrelated, streamflow climatology is a very lo..