Land Use/cover And Evapotranspiration Dynamic Change And Their Relationship In Three Gorges Reservoir Area

The three gorges reservoir area are abundant in water resource, and the evapotranspiration is frequent in activity in this area, and the surface evaporation is an important part of the surface water cycle and is of great significance for water resources protection. Since the construction of the three gorges reservoir, significant changes have taken place within the reservoir surface cover, Therefore, the effect of land use change on climate of the reservoir study has attracted many linguists’ attention.This paper chooses Landsat TM5images of the three gorges reservoir area in June1997, July2003and July2006as the basis data, by conducting field investigation, and combining with remote sensing visual interpretation methods, in accordance with the national land use type classification standard, found the three periods of land use/cover data and their change rule.and it uses the data of the meteorological site records in the reservoir area. And employs Peng-Man software calculation and ANUSPLIN interpolation formula to reveal the spatial distribution characteristics and change law of time of evaporation in the three gorges reservoir area. Finally, It further discusses the relationship between the surface evaporation and different land use types in the three gorges reservoir area.The major finding yielded in this:(1)The three gorges reservoir area land exploitation degree is higher, the land utilization is more than99%. Forest and grassland are mainly distributed in the downstream of the three gorges reservoir area.Cultivated land, construction land and unused land are mainly distributed in the upstream region. Between1997and2003, the vegetation coverage was significantly reduced, forest land and grassland area of the average decrease rate is bigger, the area of cultivated land and construction land shows increasing trend. Water area increased significantly. from2003to2006, the period of the rapid growth of vegetation coverage, gradually reduce the cultivated land and grassland, mainly to turn into a forest Construction land and waters continue to rise. Overall, land use/cover changes significantly in the three gorges reservoir area over10years, it has changed33.55%of reservoir area range.(2)The monthly evapotranspiration is larger, the water cycle activity More frequent in three gorges reservoir area. Within the distribution difference of surface evapotranspiration in large, surface evapotranspiration values larger areas are mainly distributed in the downstream area, and the evapotranspiration in the upper reaches of the phenomenon is relatively mild. In the long run, compared with1997evaporation quantity significantly reduced in the three gorges reservoir in2003, the area accounted for about46%, it mainly distributed in the downstream of the three gorges reservoir area; but the evaporation have significant increased in2006, not only more than in2003, but also slightly higher than the initial conditions of the1997, the enlarged area accounts had38%of total area of the region, the change area in downstream of the reservoir.(3) Various land use types basically control the distribution of the surface evaporation in three gorges reservoir area. It is presently obvious difference. Evapotranspiration volume average of the various land cover types. As following the change rule:water> forestland> cultivated land> grassland> construction land> unused land. The surface evaporation has a certain relationship with different surface land use. Frequent surface modification by the people has a profound influence for surface water circulation.(4) The changes of the amount of evapotranspiration and the change of the forest land has strong correlation in the three gorges reservoir area in1997and2003,2003and2006. Changes in a certain period of time evaporation Are mainly influenced by the changes of the vegetation coverage. Its change rule is:the higher vegetation coverage area, The bigger evaporation coverage is; On the contrary, the lower vegetation coverage is, the less evaporation amount is. in a long period of time, changes in vegetation coverage are main factors that affects the change of the evaporation.Through the research of the land use/cover and evapotranspiration in the three gorges reservoir area In this decade, it reveals the climatic effect of the three gorges reservoir area, to predict the future development trend, meanwhile it will be helpful for people of understanding of the three gorges reservoir area. Meanwhile, it plays an important role in the protection of.regional water resources., the conservation of the Y angtze river upstream of the water and the construction of the three gorges reservoir area ecological environment.