Temporal And Spatial Dynamics Of Land Use And Evaluation Of Ecological Effect In Hanjiang River Water Source Area Of ​​Southern

China is a country with an acute shortage of water, where per capita water resources account for only a quarter of the average world, and the difference of the spatial distribution makes water more serious shortage in north China, so south-to-north water transfer project bears allocation of the water resources in northern region. Han River upstream in southern shaanxi province is one of the important main water resources region of south-to-north water transfer project, and the changes of land use lead to their ecological environment and safety of water source region, in the other time, have a profound impact on water security and the social economic development in northern China.Land use and cover change is one of the key problems in global change research, and the ecological effect of land use change is current hotspot research issues. Based on GIS and RS, with multi-source data, such as remote sensing, meteorology, vegetation, soil, statistics, Geodatabase database built to manage spatial data and attribute data, from the analysis of land use change, based on the transfer matrix of land use dynamic degree and land use and landscape pattern index,Ⅰ quantitatively assessed the land use change situation, then estimated vegetation net primary productivity, soil conservation and water conservation caused by land use change, finally produced the ecological effect value. This study optimized the land use pattern in han river catchment, and improved the capacity of water conservation, provided the reference of the opportunity cost of compensation on land use change,then had important theoretical and practical significance on realizing national optimization allocation of water resources.Main results are as follows:(1) Ecological land increased and active region of land use change concentrated in the valley basin and the low hilly land. Cultivated land and forest land changed biggest, which cultivated land decreased by484.44km2and forests increased by425.54km2, the cultivated land transferred by forest land account for43%of the total, mainly manifested cultivated land transfer to forest land; the largest increasing is the water and construction land, which an average annual dynamic reached1.19%and0.98%respectively, but has low proportion, ecological impact is not big; The active areas of land use changes mainly concentrated in the valley basin and the low hilly land, will be the focus on land use change monitoring region.(2) Land fragmentation degree is high, the landscape spatial pattern has big differences, and connectivity has the enhanced trend. The largest patch area of forest land is364.28hm2, connectivity is highest, where plaques quantity in high mountain is little, the area is large, whereas, forest land in low mountain hills and valleys basin area brake up and plaques are numerous. Cultivated land patch number is the most,55647, in which the valley basin has good connectivity, number of patches is less and the area is large, from low mountains and hills to the first-hand, plaque is tend to decline, arable land scattered distribution, fragmentation degree is high, reflect the macroscopic characteristics of the cultivated land distribution of qinba mountain.CA, CONTAG, AI, TE, ED landscape dynamic change index shows that the gathered degree of type plaque in studied area has increased, the tendency of the connectivity enhanced.(3) Quality of the ecological effect on land use change increased significantly and spatial differences are big. of primary productivity of vegetation in2000,2006,2012is6.05×107t7.25×107t,7.42×107t, respectively; the soil conservation reached3.85×108,2.53×108and4.20×108t/a, water conservation is14.23×108,15.41X108,16.38×108, a huge number, ecological effects significantly increased, the ecological environment material production ability and the ability of water to soil rapidly ascended. Ecological effect in low quality area has focused on the valley basin, and the high value area is in north and south on both sides of the mountain. Spatial distribution show that with increasing elevation, the ecological effects of the natural vegetation coverage increased significantly. But from a dynamic perspective, the biggest increasing region focus on an altitude of1000m, is the key area of ecological quality of effector future ascension.(4) Soil erosion intensity and spatial difference are huge, where low valley basin hilly land is the key area of soil conservation work. But from the actual soil erosion coefficient, actual erosion degree in low hilly land and river valley basin area is higher, reached more than40%, the key area of ecological environmental governance.(5) Total value of the ecological effect on land use change is huge, growing, and opportunity cost of water conservation is highest. The total ecological benefits are88.257,855.23and723.97,billion yuan in2000,2006and2012; increased by15.86billion yuan. High value area of NPP, soil and water conservation value, and carbon sequestration are on both sides of the mountains, low values are in the valley basin and reflects the natural vegetation environment effect increased with the increasing elevation, but from the perspective of ecological change total value, lower value in valley basin and the low hilly land increased bigger, reflect the biggest change area of regional ecological effect of land use change is also should be the regional focus ecological compensation.(6) paper innovation points:①Based on system thinking, for the first time, this study researched soil and water conservation effect on lucc change for the middle route of south-to-north water transfer project in Han River upstream section.②On the basis of predecessors’ universal soil erosion equation, using the soil conservation measures factor and vegetation cover and management factor, soil erosion actual coefficients was obtained, which can effectively reflect the degree of soil erosion, more accurately explain the influence of human activities on the soil erosion.