Soil infiltration characteristics and Manning roughness coefficient change with the Tillage, irrigations, meteorology, Crop growth and other factors. Based on the experiment data we analysed the variation rate of the soil infiltration parameters and surface roughness coefficient in different irrigation seasons. Furthermore, we used WinSRFR4.1 to simulate the influence of the quality of irrigation and irrigation process. The results showed that the soil infiltration parameters and the surface roughness coefficient had a moderate degree of variation rate. These time variants had a significant influence on the irrigation process and the irrigation quality.

Through two years lysimeter experiments, the variation of leaf area index, water consumption and grain yield of winter wheat under different soil water deficits were analyzed. The results showed that the regular nutritional growth of winter wheat was inhibited by severe water deficit, its grain yield and water consumption were also decreased. The reduced tiller number of winter wheat was the main reason for LAI values decreased rapidly after reaching its maxima at the end of the jointing stage. The maximum yield reduction rate and water consumption amplitude of winter wheat were 50.02% and 44.44% in 2012-2013, 50.14% and 26.52% in 2013-2014, respectively. In order to achieve high yield and high WUE, priority should be avoided is continuous drought, and the recommended low limits of soil moisture index was 45%FC (field capacity), 55%FC, 70%FC and 65%FC at seedling stage, jointing stage, heading stage and filling stage, respectively.

Abstract: Non-point source(NPS) pollution is now becoming the main cause of water quality problem in Changyang reach of Qingjiang river basin. In this study, we simulated the situation of non-point pollution in this region using SWAT model. At first, by using the data of hydrological and water quality in this area from 2011 to 2013 for simulated calibration and validation, the values of R2 and Ens (Nash-Suttclife effiency) are satisfying, indicating this model performing well in simulating the runoff and yields of ammonia nitrogen and total nitrogen in this region. After that, analysis of simulation results indicated that the temporal distribution of pollution charge is accord with the runoff, while the spatial trend showed a decline from upper reaches to lower reaches. Finally, we simulated some new situations by setting filter strip, reducing the usage of fertilizer and forbidding cage culture, to figure out the reduction effectiveness of pollution amount in Geheyan reservoir area in Changyang. The reaults showed that among all the single programs, setting filter strip can make the best effect while reducing the usage of fertilizer cannot make a obvious difference. Among all the combined programs, the one using 10m filter strip can achieved the best results but the one with 2m filter strip can be the most highly cost effective program.