Comprehensive Evaluation On Soil-Water Utilization Ecological Risk Of Oasis

Shiyang river is a typical basin which is lack of water in northwest arid zone, theoasis cities relying on river basin are the cluster centers of human production and lifeand they also have a special and sensitive human-environment relationship.With thesocial and economic development of oasis towns, the pattern, depth, strength oflanduse changes and the diversification of land use type all together makefar-reaching influence on land ecological system and determine the ecologicalsecurity within the area.The water demands of industrial and agriculturual production,living and environment have been increased, the water quantity and its time-spacedistribution will also change, both will make further influence on stability of urbanstructure system and spatial evolutionary directions. By regional economic, culturaland ecological activities, the water-soil combination patterns take differentperformance within each regional scale, then comes out the ecological risks ofdifferent types.Referring to domestic and foreign assessment of the related research, this articletakes Wuwei city as the case, take water-soil resource time-spatial distributioncharacteristics and its utility process as the research objects, then constructs LUCCecological risk model, with the help of GIS and statistical method, it reveals thedynamic and spatial ecological risk change of land utilization; besides, the paperestablishes the water utilization risk model by referring to bulletin of water resourceand statistic yearbook(2003-2009)of Wuwei to comparatively analyze waterutilization risk change trend. The conclusions show:(1)During the study period, land cover landscape high ecological risk distributionarea has been expanded increasingly, the high risk landscape area got the ratio of52.30%within whole region in1987and57.52%in2010which were mainlyconcentrated on cultivated land、grassland and unused land.(2)The land use integrated risk index has increased during research period inWuwei, changes of land use pattern may produce certain degree ecological risk.(3)Water resources utilization ecological risk level has been raised upsignificantly during2003-2009. The risk rank of Liangzhou changed from slight tomoderate; the risk rank changed from moderate to lay particular stress degree ofupstream agricultural area in Gulang and Tianzhu; Minqin county in downstream areakept in severe level during study period. (4)The shortage-risk is mainly influnced by water supply and demand, the watershortage-risk value takes an overall growing trend, from1.148in2003to2.594in2009, and at present, it stays at next to high rank. During study period, populationkept on stable with a slight decrease while GDP value made steady increase. A smallfluctuation in2007was mainly dued to the change of precipitation.According to the results of water-soil utilization ecological risk assessment inWuwei city above, the paper finally puts forward some countermeasures andsuggestions against risks by refering to actual situation in different study areas.