Analysis on ecological use of water of Changchuan watershed in the Soft Rock Area of Middle Yellow River

The Changchuan watershed,Inner Mongolia,belongs to the typical region of the Soft Rock Area of Middle Yellow River.Based on experimental research data of the ecological use of water,this paper applies the GIS and scenarios analysis methods to analyse the ecological use of water of the Changchuan watershed and different scenarios of ecological construction in the water-shed.The vegetation evapotranspiration and ecological use of water at Changchuan watershed averaged 274.3mm and 370.7mm respectively.This indicates that though evapotranspiration of vegetation was quite high on the regional scale,yet the rainfall can still meet the requirement of evapotranspiration of vegetation. Generally speaking, the ecological use of water was moderate in this region.In terms of ecological use of water under different scenarios of ecological consreuction,4 land use patterns,B2RL1,namely restoring all bare land and sandy land at Changchuan watershed into woodland,brush-land or grassland,B2RL2,namely no bare land and turning cultivated land on above 5° slopes back into woodland or grassland at Changchuan watershed,B2RL3,namely no bare land and turning cultivated land on above 15° slopes back into woodland or grassland,and B2RL4,namely no bare land and turning cultivated land on above 25° slopes back into woodland or grassland can stand the water stress for a short term,but the vegetation can not grow and develop very well under the water regime of the watershed in the long run.