Abstract:

Different landuse types influnce the surface runoff,the infiltration and evapotranspiration in the soil.Changes of landuse patterns would impact the elemental distribution of water balance,as well as the changes of water conservation capacity.The hydrological response to landuse types was the basis of studies on water resource management and ecological remediation.It is important,therefore,for the reasonable utilization of water resources and the sustainable development of ecological system.The Muyang River watershed refers to the lower part of the Jinsha Jiang River basin,and is chosen as the study area in this paper.Taking the meteorological data within and nearby the study area,combining with the landuse,soil and topography data in this area as the basis,a SWAT model was built.The feasibility of the model in the Muyang River watershed was evaluated afterwards.The landuse data from 1986 to 2009 were collected.By presupposing four different scenarios of landuse changes with the intense human activities and the improving ecological system,the hydrological responses to the landuse changes in the watershed were analyzed using the SWAT model.The results indicated that the modelling error in the Muyang River watershed was+10%,and the NashSutcliffe efficiency coefficient was larger than 075 both in the calibration period and the validation period,which proved the SWAT model was suitable for the evaluation of the hydrological response in the Muyang River.The runoff decreased in accordance with the landuse pattern of 1986,2000,2009 and 1995,and the evapotranspiration decareased by the order of 2009,1986,2000 and 1995.The influence of landuse changes on runoff and evapotranspiration in the flood season was greater than that in the dry season.The runoff would decrease with the increasing area of forest.Changes of the present arable landuse type to forest or grass landuse type would contribute to the decrease of the runoff.The evapotranspiration in forest area was higher than that in grass land.Therefore,the construction of the composite forestandgrassland system was favorable for the decrease of runoff and evapotranspiration, and for the increase of infiltration.All the results will provide scientific knowledge for the water resource protection and the construction of the forest for conservation of water supply