Improvement of low flows simulation in the SASER hydrological modeling chain

The physically-based, spatially-distributed hydrometeorological model SASER, which is based on the SURFEX LSM, used to hydrological cycle in several domains Spain and southern France. In this study, modeled streamflows are validated a domain centered Pyrenees mountain range includes all surrounding river basins, including Ebro Adour-Garonne, with spatial resolution of 2.5 km. Low flows were found be poorly simulated by model. We present an improvement SASER modeling chain, introduces conceptual reservoir, enhance representation slow component (drainage) response. reservoir two new empirical parameters. First, parameters determined catchment-by-catchment basis, calibrating against daily observed data from 53 stations representing near-natural conditions (local calibration). results show, median value, (ΔKGE 0.11) respect reference simulation. Furthermore, relative bias low-flow indices calculated reported clear improvement. Secondly, regionalization approach was used, links physiographic information through linear equations. A genetic algorithm optimize equation coefficients KGE. Cross-validation test approach. KGE improved 0.60 (default simulation) 0.67 = 0.07) after execution routing scheme, 79 % independent catchments showed regionalized had performance, terms, very close that locally calibrated key benefit if allow us determine parameter basins where calibration not possible (ungauged or human-influenced basins).