Analysis of Water Resources Supply and Demand and Security of Water Resources Development in Irrigation Regions of the Middle Reaches of the Heihe River Basin, Northwest China

Based on the data for meteorology, hydrology, soil, planting, vegetation, and socio-economic development of the irrigation region in the middle reaches of the Heihe River basin, Northwest China, the model of balance of water supply and demand in the region was established, and the security of water resource was assessed, from which the results that the effects of unified management of water resources in the Heihe River basin between Gansu Province and Inner Mongolia on regional hydrology are significant with a decrease in water supply diverted from Heihe River and an increase in groundwater extracted. In addition, it was found that the groundwater level has been steadily decreasing due to over pumping and decrease in recharges. In present year （2003）, the volume of potential groundwater in the irrigation districts is far small because of the groundwater overdraft; even in the particular regions, there is no availability of groundwater resources for use. By 2003, water supply is not sufficient to meet the water demand in the different irrigation districts, the sustainable development and utilization of water resources are not secured, and the water supply crisis occurs in Pingchuan irrigation district. Achieving water security for the sustainable development of society, agriculture, economy, industry, and livelihoods while maintaining or improving the abilities of the management and planning of water resources, determining of the reasonable percentage between water supply and groundwater utilization and water saving in agricultural irrigation are taken into account. If this does not occur, it is feared that the present performance of water development and planning may further aggravate the problem of scarcities of water resources and further damage the fragile ecological system.

Optimization research on supply and demand system for water resources in the Chang-Zhu-Tan urban agglomeration

Using system analysis theory and methods, a dynamic model of a water resource supply and demand system was built to simulate trends in the supply and demand of water in the Changsha-Zhuzhou-Xiangtan （Chang-Zhu-Tan） urban agglomeration for the period 2012 to 2030. Four scenarios were examined; namely, a traditional development model, an economic development model, a water-saving model, and a coordinated development model. （i） The problem of balancing water resource supply and demand is becoming increasingly conspicuous with a growing population and a rapidly developing economy. （ii） By 2030, water demand is set to reach a total of 105.1 × 10^8 m^3, with a water supply of 5.4 × 10^8 m^3. A coordinated development model for water resource supply could meet the growing demands of socio-economic development, and generate huge comprehensive benefits. This will be the best solution for the development and utilization of a water resource supply and demand system in the Chang-Zhu-Tan urban agglomeration. （iii） We should accelerate the construction of water conservation projects, strengthen the management of water conservation, optimize economic structures, enhance our awareness of the importance of protecting water resources, hasten the recycling of waste water and environmental improvement, and promote utilization efficiency, and support the capabilities of water resources to meet our expectations.

Modeling demand/supply of water resources in the arid region of northwestern China during the late 1980s to 2010

Water demand increases continuously with an increasing population and economic development. As a result, the difference between water supply and demand becomes a sig- nificant issue, especially in arid regions. To figure out the utilization of water resources in the arid region of northwestern China （ARNWC）, and also to provide methodologies to predict the water use in future, three models were established in this study to calculate agricultural irri- gation, industrial and domestic water use in the ARNWC from the late 1980s to 2010. Based on river discharges in the region, the supply and demand of water resources at the river basin level were analyzed. The results indicated that agricultural irrigation demand occupies more than 90% of the total water use in the ARNWC. Total water demand increased from 31.97 km3 in the late 1980s to 48.19 km3 in 2010. Most river basins in this arid region were under me- dium and high water stress. Severe-risk river basins, such as the Shiyang river basin and the eastern part of the northern piedmont of the Tianshan Mountains, were found in this region. It was revealed that the water supply became critical from April to May, which was the season of the lowest water supply as determined by comparing monthly water consumption.