Theory Of Water Resources System Coupling And Its Application To Study Of Water Resources And Hydrology In Jinghe River

Water resources system of watershed is a coupling system with natural system and man-made system. Climate changes and human activities have direct influence on water resources. In addition, human activities can also change the underlaying surface condition of river basin and the formation mechanism of runoff. Therefore, it's important to reveal the role and effect of climate changes and human activities on water resources system and to perform the evaluation and utilization of watershed water resources. This dissertation consists of two components, the theoretical research part and the applied one. In the theoretical part, (1) the theoretical basis of water resources system coupling has been expatiated, the model of water resources coupling system has been built and the fractal formulas for the elasticity coefficients of the model have been proposed, which offers one simple and effective tool to analyze human activities of watershed; (2) spatial autocorrelation of watershed hydrological elements has been analyzed with geostatistics and the Krigine interpolation method has been selected by comparing; (3) on the basis of the characteristic of runoff and water resources utilization, a grade statistical method to calculate coefficient of abandoned water in flood season has been presented to determine effectively and conveniently the river available amount of water resources under different sand limit of river water resources utilization, which provides a new approach for the study of sustainable exploitation and utilization of watershed water resources. In the application part, the characteristics such as the evolvement of hydrological elements, the impact of climate change and human activities etc. have been analyzed deeply with the presented theories, models and methods in this study and some innovation achievements have been obtained. Major results obtained are shown as follows:(1) The precipitation of Jinghe River Basin shows strong spatial autocorrelation. The mean annual precipitation exhibits a decreasing trend from south to north in spatial distribution and a distinct decreasing trend in temporal distribution. The interannual change of mean annual precipitation is evident. The values of coefficient of variation (Cv) for rainfall decrease from the north to the south, the west to the east of the Jinghe River Basin. The evaporation capacity of Jinghe River Basin shows a north-to-south decreasing trend in spatial distribution. The interannual change of evaporation is rather distinct. The values of Cv from evaporation are smaller than those from rainfall, which demonstrates that the interannual change of evaporation is weaker than that of precipitation. The air temperature in the south of Jinghe River Basin is higher than that in the northern. The watershed has a distinct increase of 0.71℃in temperature from the year of 1984.(2) The natural annual runoff from the hydrologic station of Zhangjiashan in the Jinghe watershed exhibits a remarkable decrease trend, which has close relationship with the decrease trend of precipitation in the river basin. About half of the decrease degree of natural annual runoff from Zhangjiashan has been resulted from the decrease of precipitation. The precipitation change in Jinghe River Basin is the most important influence factor on natural runoff change.(3) The influence of mean annual precipitation from the watersheds controlled by hydrologic station of Yangjiaping, Yuluoping or among the station of Yangjiaping- Yuluoping- Zhangjiashan on the natural annual runoff of Zhangjianshan over 70-year (from 1956 to 2004) time periods with the approach of stepwise regression has been carried out. Results demonstrate that when the mean annual precipitation from the watershed controlled by Yangjiaping varies 10mm (532.5mm±10mm), the natural annual runoff of Zhangjiashan will vary 0.011 billion m~3 (1.98 billion m~3±0.011 billion m~3), while the precipitation from the watershed of Yuluoping or Yangjiaping- Yuluoping- Zhangjiashan varies 10mm, respectively, that is (513.5mm±10mm) or (591.8mm±10mm), the natural annual runoff of Zhangjiashan will vary 0.024 billion m~3 (1.98 billion m~3±0.024 billion m~3) or 0.010 billion m~3 (1.98 billion m~3±0.010 billion m~3).(4) On the basis of system theory and the coupling relationship of water resources system, the coupling system of water resources was built. The coupling of natural hydrological process and influence from human activities of man-mad system has been achieved. A fractal method has been presented to determine the two elasticity coefficients, that is, the input-to-output one and the inner state-to-output one, of the water resources coupling system. Therefore, the study on influence of human activities is easy to perform.(5) The influence of human activities on runoff has been carried out based on the presented model of water resources coupling system. The performance of the proposed water resources coupling model is compared with that of other methods used by other researchers. Results show that data demanded for the presented model in this study is few and easier obtained, the calculating process is simpler and the calculating results are more rational and credible with the proposed water resources coupling model in this study, which offers a simple and efficient tool to analyze the influence of human activities on runoff.(6) If the influence intensity of human activities on runoff is defined as the ratio of influence amount of human activities on runoff to natural runoff, the influence intensity is only 0.071 before 1970's, while 0.104 in 1970's, 0.132 in 1980's, 0.168 in 1990's and 0.270 in 2000-2003, which shows that the influence intensity increases. The influence intensity before 1970's is very small and the state of river basin at that time period can be considered as the natural one. The influence intensity becomes stronger and stronger after 1970's.(7) The available amount of river water resources is controlled by the smallest amount of water required by the inner river entironment and the flood discharge hard to control and utilize or abandoned flood amount in flood season. A grade statistical method has been proposed to calculate the available amount of river water resources based on the runoff characteristic of Jinghe River. The results from the presented grade statistical method are compared with those from the traditional method. Results demonstrate that the results from the grade statistical method are more rational. When the sand limit of river water resources utilization is set as 10 percent, according to the results of the grade statistical method, the mean annual available amount of river water resources from 1981 to 2001 for Jinghe River is 0.987 billion m~3, the available amount of diversion project for Jinghuiqu irritation district is 0.866 billion m~3, the available potential amount of diversion project for Jinghuiqu irritation district is 0.509 billion m~3; the ratio of the available amount of diversion project to the natural runoff is 0.4492; the ratio of the available potential amount of diversion project to the natural runoff or the available amount of diversion project is 0.2640 or 0.5878.(8) The available amount and the available potential amount of diversion project for Jinghuiqu irritation district will increase with the increase of the sand limit of river water resources utilization. For example, when the sand limit of river water resources utilization is 12%, 14%, 16%, 18% or 20%, the mean annual available amount of diversion project for Jinghuiqu irritation district over 21-year (from 1981-2001) time periods is 0.878 billion m~3, 0.887 billion m~3, 0.894 billion m~3, 0.899 billion m~3 or 0.907 billion m~3, respectively, which is larger 0.012 billion m~3, 0.021 billion m~3, 0.028 billion m~3, 0.033 billion m~3 or 0.041 billion m~3 than that of 10% sand limit of river water resources utilization; the available potential amount of diversion project is 0.521 billion m~3, 0.531 billion m~3, 0.537 billion m~3, 0.543 billion m~3 or 0.551 billion m~3, respectively, which is larger 0.012 billion m~3, 0.021 billion m~3, 0.028 billion m~3, 0.033 billion m~3 or 0.041 billion m~3 than that of 10% sand limit of river water resources utilization.