Environmental Change Monitoring - A Case Study in the Region of Yinchuan, Ningxia, China From July to Sept. in 1987: 96.4mm in Yinchuan and 149.3mm in Xining (TM images acquired on 20 Sept.); From June to Aug. in 1999: 78mm in Yinchuan and 278.4mm in Xining (ETM images acquired on 12 Aug.). Between 1999 and 1987, a difference of –18.6mm in Yinchuan and 129.1mm in Xining is observed. Thus the rainfall varies probably from region to region in the upper reaches of the river. It is difficult to say that the river surface narrowing is a result of precipitation reduction in the region of Yinchuan. Hydraulically, the river has been largely exploited during the last decades: damming in the upstream valley. Currently, five great hydroelectric power stations have been built up: Longyangxia, Lijiaxia, Yanguoxia, Bapanxia and Qingtongxia. This explains partially the impacts of human activity on the flow and surface of the river. In agriculture, local people have made use of the river water for irrigation and pisciculture in northwestern China, especially in the Yinchuan Plain. With the extension of croplands, fish-ponds and water reserves against the aridity, river water has been increasingly extracted. An increase of 49km2 in water surface in the region is a good sign. The use even overuse of water from the river may be also one of the factors influencing the surface narrowing of the river. Surely, the climate change has made a certain contribution to, however, the human activity should have played a leading part in this narrowing. In the setting of global warming, the running course is likely to be dried after 2010 in the study area if the cropland extension and abusive use of water continue in the upper reaches. The lower reaches in the scope of Henan and Shandong have become from time to time dried. This phenomenon reminds us of the importance to save and control the mother river of China. Under the dryer and warmer background, how to exploit the river and how to allocate the feasible water quantities to each province in the upper and middle reaches are a challenge for the decision-makers. 6. CONCLUSIONS AND REFLECTIONS The research uncovers that 11.7% of the total territory in the region of Yinchuan has evolved since 1987, among which the farmland extension — a conversion from the wild sandy land, is the most outstanding environmental change (around 471km2) and associated with the DAgricultural output (R2 = 0.731). However, the agricultural output plays an unsignificant role in the economy of the region (11.6% of the total GDP growth).  Figure 4 : Precipitation recorded in two major stations in the upper reaches of the Yellow River The urban extension, driven by the DUrban population (R2=0.971), having consumed 36km2 of previously cultivated land and enjoying 3.6% of the total environmental change, is related to 88.4% of the GDP growth. The changes in water surface, narrowing of the river, etc, have been observed. Water resource is surely the first essential for the socio-economic development. However, abuse, or to a certain sense, waste in water, has lead to an increase in water-body surface, formation of marsh, and locally soil salinisation. Probably, the abuse would not only happen in the region of Yinchuan but also in all upstream regions of the river, as local people fight for water for their agricultural and industrial development. In this way, how can the river not be dry in its downstream? No desertification was observed. However, the signs of environmental degradation marked by vegetation disappearance, soil salinisation, etc, have taken place due to deforestation, overgrazing, exploitation of the natural resources (e.g., coal) and poor environmental management. The coal mining in the mountains (e.g., Shitanjing, Ruqigou), especially, some poorly organised private mining in the valleys and coal industries in Shizuishan, have provoked an environmental degradation, e.g., air pollution, soil erosion, locally destruction of the cultivated land and covering of coal residues and dusts around mines and transport routes. These coal mining related developments have brought about an improvement in the economy of the region but at a cost of environmental degradation. It is necessary to take certain feasibly effective measures to evaluate the potential impacts on the environment before the colliery exploitation. The aridity can be a priori a disadvantage, but the leading cause provoking the impoverishment of soil is the human activity, which is deeply related to the complex socio-economic and political backgrounds. The future confronted with is not too optimistic: no much arable land left for the cropland extension, no much water resource available for the future development, and the Yellow River might become dry… These are worthy of thinking and thinking in the sustainable development planning and environmental management. ACKNOWLEDGEMENT The author wants to thank first Prof. Eric F. Lambin for his supervision and strong support throughout this study. A gratitude will be sent to the Federal Office for the Scientific, Technical and Cultural Affairs (OSTC) of the Belgium Government for funding the research of the Sino-Belgian co-operation project on Northwest China (Contract No.: BL/10/C15). A cordial thank will go to Dr H. Yoshida and Fukui Research Group, Keio University, Japan, for their permission to access the Landsat TM data (1987). The author is grateful to the Chinese partners, especially, Ningxia Remote Sensing Centre and Mr Wenfeng Zhang, for their reception during the field investigation and provision of the topographic maps and socio-economic data so that this research has been achieved smoothly. Finally, a personal thank would be given to Dr Zhengping Wang for his contribution of the meteorological data of 1999 concerning the Yinchuan City. REFERENCES
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