Abstract: It is very difficult to simulate hydrological processes in alpine basin because of the impact of ice-snow and limited availability of ground observation stations. Satellite imagery is an attractive alternative to supplement ground based data in ungauged basin. The Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite sensors are particularly attractive due to their high temporal and spatial resolution. The objective of this study is to integrate temperature data with meteorological stations and SCA (Snow Covered Area) estimated from MODIS into Xinanjiang Ｍodel and test if MODIS data could be helpful for runoff modeling in an ungauged alpine basin. The analysis was performed for Niqu Basin in the upper reach of Yangtze River. The study was carried out as follows. Firstly, a critical temperature was acquired according to SCA from MODIS data for judging the periods with snow accumulation, snow melting and no snow. Then the precipitation form was identified and snowmelt water equivalent was computed accordingly. Finally the classified precipitation was as input to the Xinanjiang Model for simulating runoff series. The simulated runoff data by Xinanjiang Model with such a modified input were compared with pure precipitation input. The result indicated that model performance with the modification scheme of precipitation was better than that with original input of precipitation. The result suggests the potential for developing modification scheme and the possibility of improving the accuracy of the prediction of hydrological processes for water resources management and ecological water demand in ungauged alpine basin by Xinanjiang Model.

Key words: ungauged alpine basin, hydrological processes, MODIS, Niqu basin, Xinanjiang Model