Evaluation Of Ecosystem Health Based On RS And GIS Heihe River

Heihe basin is a continental river basin which is important in the northwest of China, as it is the lifeblood of socio-economic development. Since1949, its ecological environment has deteriorated increasingly because of the movement, such as wasteland reclamation and filling a lake for farming. In order to restrain the deterioration, programs about short-term comprehensively management of Heihe river basin were launched in2001. Therefore, studying spatio-temporal variation rules of its ecosystem health status has important theoretical guiding significance to comprehensive management of Heihe river basin and empirical significance to the sustainable development of Heihe river basin.Based on RS/GIS, an evaluation index system is established by PSR model and a comprehensive index model is used to evaluate the health status of the ecosystem. Then, the health status of Heihe river basin from2000to2010is monitored dynamically and the influencing factors of ecosystem health status are analyzed deep. The main conclusions are as follows:(1) The temporal and spatial variation characteristics of ecosystem health status from2000to2010in Heihe river basin are analyzed.In the time dimension, its health degree rises from2000to2010. The differences of healthy degree narrow inside of the region. The ecosystem structure tends to stabilization, however, it is still in the critical state. It shows that the ecosystem health level of Heihe river basin has been improved, but it is still coerced in a strong degree.In the space dimension, the years of average of ecosystem health index is in the range between0.34and0.58in Heihe river basin. The average of these areas, such as Gaotai, Jinta and Ejinaqi, is in the range between0.34and0.40. The average of Shandan, Qilian and the central of Sunan is in the range between0.40and0.45. The average of Jiayuguan, Jiuquan and the west of Sunan is in the range between0.45and0.50. The average of Zhangye is in the range between0.50and0.58There are five types on the changes of ecosystem health of Heihe river basin in the past11years, including the only obvious variation zone, slightly worse zone, no obvious changes zone, slightly better zone, obviously better zone. And there are no significant variation zone and significantly better zone. The only obvious variation zone is distributed in the north of Shandan County, which is a small area and accounts for0.004%of the total area. The slightly worse zone is distributed found in Qilian, the southeastern of Sunan, Shandan, Zhangye, Gaotai and the Local local area of Minle, the area which accounts for23.01%of the total area. The no obvious changes zone is distributed in the northwestern Sunan, Minle, the most parts of Linze, Jinta and the south of Ejinaqi, accounting for50.97%, which has the largest proportion. Jiayuguan, the west of Jiuquan,the edge of Swan lake in Ejinaqi belong to the slightly better area, which accounts for15.28%. The area of Swan lake in Ejinaqi belongs to the obviously better zone, accounting for10.74%.(2) The temporal and spatial variation characteristics of ecosystem health from2000to2010in the each cities of the Heihe river basin are analyzed.In the time dimension, there are obvious differences on the changes of ecosystem health in the each cities of the Heihe river basin. The ecosystem health index declines in Zhangye, Minle, Shandan, Qilian, Sunan, Linze, Gaotai, while the ecosystem health index rises in Jiuquan, Jiayuguan, Jinta, Ejinaqi. It shows that the ecosystem of the former is deteriorated, however, the ecosystem of the latter is improved.In the space dimension, the health degree of ecosystem from2000to2010is high in Zhangye, Minle, Qilian, Sunan, Shandan, Jiayuguan, Jiuquan and Linze, whose ecosystem health index is over0.4. But the health degree of ecosystem is low in Gaotai, Jinta and Ejinaqi, whose ecosystem health index is below0.4in2000. With the implementation of the management work in Heihe river basin, the indexes of Ejinaqi and Jinta reach the highest point in2010,but they are still below the health level of the other eight cities.(3) The trends of ecosystem health development of each cities are predicted by GM (1,1) model. The health status of these four counties, Jiayuguan, Jiuquan, Jinta and Ejinaqi rises. And the health status of Jiayuguan, Jiuquan and Jinta will reach the more healthy level in2022,2024and2026respectively. The health status of Ejinaqi, whose ecosystem health is improved quickly, will reach this level in2086, because its ecosystem health status is low relatively now.The health status of these six cities, Gaotai, Qilian, Linze, Minle, Zhangye, Sunan, and Shandan declines. The health level of Gaotai is the lowest and its rate of degeneration is the fastest, which will reduce to the pathological level in2078. The health index of Qilian is0.413, which will drop to sub-0.400in2042. The health index of Linze County will drop to sub-0.400in2016and to0.300in2060. The health index of Minle and Zhangye will drop to sub-0.400in2076and in2090respectively. The rate of decline is relatively slow in Sunan and Shandan and their health degree is same in2010. Their health index are0.430and0.431and will drop to sub-0.420in2044and2068respectively. The health level of Sunan decline more quickly, whose health index will drop to sub-0.400in2096. However, Sandan’s will still more than0.410at that time.(4)The contribution degree of the three subsystems to the integrated ecosystem health is different in the each cities, which shows that the degree of ecosystem health changes are affected by the different subsystems. Zhangye City and Jinta County are influenced by the pressure subsystem. Linze and Gaotai are influenced by the status subsystem. Jiayuguan, Jiuquan, Ejinaqi, Minle, Shandan, Qilian and Sunan are influenced by the respose subsystem. At last, according to the analysis results, this study put forward the following measures:increase the effective quantity of water, dividing into different areas to management, strict implementation the water diversion program, protection by padlock and establishment the ecosystem health system.