Land Use And Land Cover Change Modeling Based On Water Restriction Mechanism In Zhangye City

Land use and land cover change(LUCC), is the main reason and response of globe change, has a closely relation with sustainable development. LUCC modeling is the important way to predict future land use change. This thesis apply the advanced model "CLUE-S", to model land use and land cover change in Zhangye City.There is no precedent to model land use and land cover change of arid region in China. And Zhangye City located in the transition of three physical geographical region of China, is the significant part of North-west arid region, which is the sensitive area and zoological brittle zone. The evolutive process and mechanism of land cover change law is different from east region. Therefore the study of LUCC modeling in Zhangye City has a vital theory and practice meaning.The modeling period is from 2000 to 2020. The study area is 36306 km2.The base map is the land use map from TM image of 2000. Land use type is redivided into 6 types,- (1) Field, (2)Woodland, (3)Grassland?(4)Water area, (5)City and Town, (6)Unused area. And 7 kinds driving factors, which represent import contribution to LUCC in this area were chosen. They are, distance to city, distance to river, distance to road, population density, altitude, slope, and slope aspect, which is produced with Arcview spatial analysis means. Then the weighting coefficient î–™) of every land use was analysed use with SPSS 10.0. Modeling builds 3 kinds scenarios according to water resource restriction, namely modeling LUCC when available water resource is 18x108m3, 26.5x108m3and 35x108m3 respectively in this region.Each proportion of 6 kinds land use types in initial year of modeling respectively is (1) Field: 10.45%, (2) Woodland: 10.07%, (3) Grassland: 32.36%, (4) Water area: 2.17%, (5) City and Town: 1.05%, (6) Unused area: 43.90%o And to the end year of modeling, the proportion of 6 land use types in three scenarios respectively is (1)Field: 6.47%, 8.13%, 9. 57% (2)Woodland: 15. 70%, 23.18%, 33. 86% (3) Grassland: 33. 47%, 36. 04%, 36. 73% (4) Water area: 2.17%, 3. 30%, 2. 22% (5) City and town: 1. 05%, 1. 25%, 1. 67% (6) Unused area: 41.14%, 28.11%, 15. 96%.The modeling result are (1) With 3 scenarios, the area of field decreases all, the reduced quantity is negative correlation with available water resource, namely the more available water resource, the more the area reduced quantity (2) The increasing of woodland area isvery large, woodland area and available water resource are in positive correlation . (3) Grassland also increases in three scenarios, and the more available water resource ,the more the increasing area, although the increasing area is less than woodland ,the increasing area and available water resource still are in positive correlation. (4) The change of water area is not visible .There is no change in scenario 1 ,and a little increasing in scenario 2 and scenario 3. (5) City and Town don't change in scenario 1. And increases 19.5% in scenario 2, 59.19% in scenario 3.So the area of city and town also is in positive correlation. (6) The unused area decreases unceasingly. The reducing area is very large. The decreasing rate is 6.28% in scenario 1,35.98% in scenario 2,63.65% in scenario 3.Finally verified the model with ROC(relative operating characteristic) method. Thefitness of every land use type is, field: 0.792, woodland: 0.841, grassland: 0.825, water area: 0.798, city and town: 0.779, unused area: 0.902. The fitness is more than 0.5 of all, the fitness is very good.