PROGRESS IN GEOGRAPHY ›› 2009, Vol. 28 ›› Issue (4): 575-583.

• Original Articles •

### Effects of Spatial Resolution of Soil Data on Hydrological Processes Modeling

YE Xuchun1,2, |ZHANG Qi1, LIU Jian1,2, |LI Lijiao1,2, |ZUO Haijun1,2

1. 1. Nanjing Institute of Geography and Limnology, State Key Laboratory of Lake Science and Environment|Nanjing 210008, China； 2. Graduate University of Chinese Academy of Sciences|Beijing 100049, China
• Online:2009-07-25 Published:2009-07-25

Abstract:

The prediction accuracy of a distributed hydrological model depends on how well the model input spatial data describe the characteristics of the watershed. Especially, in a large scale catchment, could a higher resolution of input data contribute to a more accurate result? As an important component of input data, soil information directly impacts the accuracy of the simulation of hydrologic model. In this study, surveyed soil data with two different spatial resolutions were used as input data for a SWAT model simulation in a large scale catchment of Xinjiang River basin (15535km2) in China. Simulations of stream flow, soil water storage and evapotranspiration using the two soil datasets were compared, and the applicability of fine resolution of soil data was analysed. The results indicate that the different resolutions of soil data have a great impact on the distribution of hydrological response units in the SWAT model, but show no obvious differences in stream flow simulation and evapotranspiration (ET). Our observations also show that the lower resolution data improved slightly in average monthly stream flow simulation before and after calibration, but there is no substantial difference. The finer resolution data produced a higher monthly soil water storage (SW) simulation than the lower resolution data across the whole watershed during the simulating period. Results also show that the evapotranspiration calculation method in the SWAT model is insensitive to soil resolution. The implications of this study are that improvement of the resolution of soil data does not necessarily contribute to a more accurate prediction of streamflow in large scale catchments. In practical studies, modellers need to select an appropriate resolution of soil data depending on the scale of watershed and the level of accuracy required, and also need to consider the principle of the model and the physical meanings of some key parameters to explain the simulation result.