Study of watershed hydrological spatio-temporal variability analysis based on information entropy

The Chaobai River Basin lies in the upper reaches of the Hai River Basin and also the upstream of Miyun Reservoir which is the Beijing municipal tap water main resources. The precipitation is one of the most important hydrological factors and its variability analysis is crucial for further understanding hydrological process and hydrological modelling. Traditional spatial variability was quantitatively described using coefficient of variation (Cv) based on statistics. Combining information entropy theory with GIS spatial analysis technology, the spatio-temporal variability of annual precipitation is analyzed. A new spatio-temporal variability analysis method which is based on the differential information entropy relative measure is also presented. This study was conducted using 58 gauge stations rainfall data and 2 gauges streamflow data of Chaobai River Basin during the period from 1973 to 2002. Results of this study not only show that the new spatio-temporal variability analysis method is feasible and effective, but also indicate that the rainfall isn t the main reasons of Miyun Reservoir s inflow rapid reducing.