Study On The Driving Forces Of Urban Water Consumption Change In Xi'an

With the rapid development of urbanization process, Xi'an urban areas have been expanding, non-agricultural population have been increasing, economy has been growing and industrial structure has been upgrading, which making urban water consumption, urban water structure and urban water use efficiency are also taking place along corresponding changes.Urban water consumption contradiction between supply and demand become increasingly prominent, which will seriously condition the city's sustainable development.At the same time, climate is also experiencing evident changes. In the context of climate warming and drying trend,there is likely to increase urban water supply and demand furtherly, which will add new variables to increasingly serious urban water consumption change.Therefore, under the combined influence of climate change factors and urbanization development factors, this paper researches into urbanization level of Xi'an that influences on urban water consumption changes and trends of urban main sectional water, researches and analyzes the urban water consumption's response to the climatic variation,explores the effects of climatic factors fluctuations on the urban water consumption.On the base of it, the urban water consumption are predicted and several measures about sustainable utilization of urban water resources are proposed.That means great practical significance to promote the sustainable development of Xi'an city.Based on the features of the inter-annual changes and structures in urban water consumption,the relationships between urban water consumption and its driven factors as urbanization and climate change are discussed and analysed by using the related mathematical statistical models,according to the urban water consumption's data and the urbanization indicator data and the climate data series collected from 1978 to 2007 in Xi'an. And these human-driven factors and climate-driven factors influencing on urban water consumption and urban water structure are explored by using SPSS 15.0 software and Morlet wavelet procedures and so on. On the base of it, GA-BP-ANN network prediction model for the urban water consumption is established,and several measures about sustainable utilization of urban water resources are proposed. Those provide scientific reference to allocate urban water consumption reasonably and work out water-saving measures.The main conclusions are shown as follow:(1) On the whole, urban water consumption of Xi'an has gone through a variety process from slow increasing to rapid increasing to increasing-converge towards a stable state except for individual years. After 1998, the urban domestic water consumption began more than the urban productive water consumption,and then Xi'an became a city with the type of mainly domestic water consumption.(2) The relationships between urban water consumption and its driven factors as urbanization and climate change are entered regression analysis by using double-logarithmic function model.The results show that:The urbanization factors which affect urban water consumption are the main driving factors and they have great consistency; Also climatic factors have a certain degree of contribution on urban water consumption. With the climate warming and drying in Xi'an, dry and hot weather increase, people increase urban water demand to adapt to these changes.(3) The relationship between urban water consumption and logarithm of urbanization degree in Xi'an shows up linear growth, but the growth rate gradually decreases.Urban main sectional water and main urbanization indicators as non-agricultural population and economic development are fitted by matched curves. The result shows that urban domestic water consumption increase monotonically with the population urbanization rate,and the curve-fitting between them is similar to the form of exponential curve. That means people would increase urban water demand with the rising population urbanization rate, leading to urban domestic water consumption rising. The relationship between urban production water consumption and GDP show "∽" type line trend which is a manifestation of the Environment Kuznets Curve. That can be interpreted as urban production water consumption and economic development and industrial restructuring have great relevance.(4) Climate warming is an important factor which lead to urban water fluctuations changes.Then the urban domestic water consumption is more sensitive in response to temperature change, the correlative coefficients between it and the annual mean temperature,the annual mean maximum temperature,the annual mean minimum temperature respectively reach to 0.644,0.437 and 0.721. But the correlationships between it and annual precipitation anomaly percentage, summer precipitation anomaly percentage, autumn precipitation anomaly percentage are not significant, the correlative coefficients are rather poor,and the correlative coefficient between urban domestic water consumption and autumn precipitation anomaly percentage is -0.229.Using polynomial model to extract the climatic water consumption, the deviated coefficient is 10.97. That means its fluctuations discreteness is lager,so the vulnerability of the climatic water consumption is relatively stronger.(5) According to main driving factors influencing on the urban water consumption, GA-BP-ANN network prediction model is built. The forecasts of the urban water consumption, the urban domestic water consumption and the urban production water consumption are obtained from 2011 to 2015 through the network training simulation. The forecasts of the urban water consumption in Xi'an are 40816 million m3,42866 million m3,44857 million m3,43844 million m3 and 45904 million m3,and the forecasts of the urban domestic water consumption are 16785 million m3,19957 million m3,20583 million m3,20729 million m3 and 23094 million m3, and the urban production water consumption are 5938 million m3,5945 million m3,6790 million m3,6527 million m3 and 7411 million m3.The development between social, economic and resource of Xi'an city are lack of coordination because the urban water demand is still increasing. Therefore, several measures about sustainable utilization of urban water resources are proposed in the context of limited water resources.Those can provide scientific reference to promote the sustainable development of Xi'an city.