CHIRPWeb, an online tool for providing a bias corrected CHIRP grid dataset using field measurements

Precipitation data play a crucial role in hydrological modeling. Although rain ground stations data have traditionally been used, their uneven distribution and numerous gaps raise some doubts about their reliability. As a result, satellite rainfall data sets are increasingly used in hydrological assessments. However, these estimates are prone to inaccuracies due to instrumental problems or theoretical simplifications, and it is essential to eliminate systematic errors before using them in hydrological applications. This paper presents an online tool to select a CHIRP grid in a region and correct its bias derived from field measurements. Furthermore, the tool is designed to generate SWAT-compatible rainfall data input. As an example of the application, the performance of the SWAT model in the Spanish Oskotz river basin has been evaluated. In general, better results are achieved with the corrected grids, obtaining improvements of around 30% in Nash-Sutcliffe efficiency and decreasing PBIAS by around 15%.