Reserch On Lucc Of The Water-level-fluctuating Zone Of The Three Gorges Reservior Based On 3S Technology

The water-level-fluctuating zone appears periodically because of the seasonal fluctuation of water level in the reservoir.It is necessroy to explore the land land resources of water-level-fluctuating zone,which can play a key role to make a harmony between the residents and eco-environment. But there are some problems we should solve before land utilizaiton in the water-level-fluctuating zones,which foucu on land resouce problem,land use and cover change mechanism and land use change tendency forecast.The Three Gorges Project which has considerable comprehensive benefits in the flood control,power generation and navigation is one of the greatest hydro-junction engineerings.Since the operation plan of this huge reservoir is to'store clean water and disharege turbid water'after Sep.2009,the water level will alternate between 145m and 175m,finally,there will be forming water-level-fluctuating zone.In this paper,remote sensing images,DEM and other data were employed to make ananlsis on the quantity structrue and spatial pattern of land use and cover change in water-level-fluctuating zone,with integrated 3S technology and landscape indices.Then the markov chain model was applied to land use change tendency forecast.Finally, some contermeasures were brought forward to improve the land resource in the water-level-fluctuating zone.The main research results were as follows:(1)The total area of Wushan County is 24.02km2 , and the area of water-level-fluctuating zone is 24.02km2,which occupies 0.81% of the total land.(2)The quantity and the type of land resources in the region of water-level-fluctuating zone of Wushan county in 2000 are analyzed,and also the distribution in different elevation and slope.The results show that in 2000,the area of cultivated land,forest land,grassland,waters,waters and unutilized land is respectively 10.55km2,6.11km2,3.38km2,3.09km2,0.83km2 and 0.04km2,accounting for 43.90%,25.49% ,14.12% ,12.83% ,3.46% and 0.17% respectively in the area of the water-level-fluctuating zone.The area of the 145m～155m elevation zone is 8.986km2,the 155m～170m elevation zone is 10.667km2,the 170m～175m elevation zone is 4.367km2,accounting for the total area of 37.4%,44.41% and 18.18% respectively. The area of the slope in the 0°～15°,15°～25°and >25°is 46.25%,28.56% and 25.19%.(3)Land use and land cover change in the water-level-fluctuating zone from 1986 to 2000 has been studied.The results shows that in the fourteen years from 1986 to 2000 year,the area of cultivated land and construction land increased,the forest land and grassland decreased,the waters and unutilized land almost had no change.The change of use types of land resources mainly occurred on cultivated land,forest land,grassland and construction land.Cultivated land mainly convert to forest and construction land,the conversion area is 0.293km2 and 0.247km2 respectively.The largest area of convert-out is 0.594km2 which mainly convert forest to cultivated land.The grassland mainly convert to cultivated,forest and construction land,the conversion area is 0.346km2.(4)To the extent of land use change,composite index of land use has increased from 247.43 to 250.69 during the year of 1986-2000 in the range of water-level- fluctuating zone.It shows that the extent of land use change is in the degree of development period,but the level of use is low and the pace of development is slow.(5)The spatial change and its evolution of landseape pattern from 1986 to 2000 year the range of water-level-fluctuating zone has been researehed by using quantitative indices of landscape pattern.The result shows that: cultivated land is the matrix of landscape;the Patch Cohesion Index which decreased because of human activity is high both in 1986 and 2000 year,Shannon's Diversity Index increased from 1.361 to 1.378 and Shannon's Evenness Index increased from 0.759 to 0.769 between 1986 and 2000 year,it shows that the diverse types of landscape inclined to equality,Contagion Index decreased from 58.562 to 57.944 between 1986 and 2000 year,it shows that the number of small patches was increased.(6)The trend of land use and land cover change of in the region of water-level-fluctuating zone which is forecasted by markov chain model shows that cultivated land,forest land and grassland will reduce,construction land and unutilized land will grow,and waters will not chang if the Three Gorges Project had not building.(7)Some methods and countermeasurs were put forward to coorinate the land resouce protection and explotation.