Eco,environmental sensitivity is defined as the possibility of formation and generation of eco,environmental problems in a given region influenced by natural factors.The Heihe River Basin,located in the northwestern China,is a typical arid and semiarid area.In recent years,the original ecological balance has been seriously destroyed in this basin,many environmental problems such as land desertification,soil salinization or alkalization and soil and water loss,occurred along with rapid population growth,development of industrial and agricultural production and increase of water consumption.For regional social and economic sustainable development,strengthening eco,system management at basin scale is a prerequisite.One of the most effective methods is to identify the critical or sensitive area which is easy to be degraded.Based on investigation and previous studies,integrated assessments of sensitivity to water erosion,desertification,salinization and its spatial distribution in the Heihe River Basin have been done by GIS spatial analysis method,and the spatial distribution of eco,system sensitivity and service importance were characterized.The ecological function regionalization is worked out according to the assessment results,and the ecological protection and construction measures for each ecological region are also recommended. The results show that:(1)In the total area of sensitive or more sensitive region,the more sensitive region to soil erosion makes up 2.05% of the total area of the basin,mainly in Qilian mountain region,and there is no most sensitive region to soil erosion.The most sensitive region to desertification covers 37.06%,mainly in Ejina County,the lower reaches of the Heihe River,and the more sensitive region to desertification covers 5.59%,mainly at the northwest edge of Badanjilin Desert and the middle,lower reaches of the Heihe River.The most sensitive region to salinisation makes up 0.37%,mainly locating in the oasis of the middle reaches of the river.And the more sensitive region to salinisation accounts for 0.56% of the total area,mainly in the west and the north of Ejina County.(2)The sensitivity distributed regions are the same regions suffering from eco,environmental problems,and these regions should be taken as priority area for ecological protection and constru,ction.(3)Based on the above assessment,seven eco,functional zones were subdivided.They are:Mazong Mountain Hill Eco,region,High Torso Plain and Gobi Eco,region,Ruo River Delta Eco,region,Erosion,protected North Corridor Shrub Eco,region,Farmland,protected Fluvial Plain Eco,region,Low Mountain Meadow and Dry Farmland Eco,region,and Qilian Mountain forest and Meadow Eco,region.
