Yes / The upper reach of the Yellow River from Daliushu to Shapotou consists of five bends and has complex topography. A two-dimensional Re-Normalisation Group (RNG) k-ε model was developed to simulate the flow in the reach. In order to take the circulation currents in the bends into account, the momentum equations were improved by adding an additional source term. Comparison of the numerical simulation with field measurements indicates that the improved two-dimensional depth-averaged RNG k-ε model can improve the accuracy of the numerical simulation. A rapid adaptive algorithm was constructed, which can automatically adjust Manning's roughness coefficient in different parts of the study river reach. As a result, not only can the trial computation time be significantly shortened, but the accuracy of the numerical simulation can also be greatly improved. Comparison of the simulated and measured water surface slopes for four typical cases shows that the longitudinal and transverse slopes of the water surface increase with the average velocity upstream. In addition, comparison was made between the positions of the talweg and the main streamline, which coincide for most of the study river reach. However, deviations between the positions of the talweg and the main streamline were found at the junction of two bends, at the position where the river width suddenly decreases or increases. / National Natural Science Foundation of China (Grants No. 11361002 and 91230111), the Natural Science Foundation of Ningxia, China (Grant No. NZ13086), the Project of Beifang University of Nationalities, China (Grant No. 2012XZK05), the Foreign Expert Project of Beifang University of Nationalities, China, and the Visiting Scholar Foundation of State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, China (Grant No. 2013A011).

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Several studies indicates China is experiencing a water crisis, were several regions are suffering of severe water scarcity and rivers are heavily polluted. On the other hand, water is used inefficiently and wastefully: water use efficiency in the agriculture sector is only 40% and within industry, only 40% of the industrial wastewater is recycled. However, based on statistical data, China’s total water resources is ranked sixth in the world, based on its water resources and yet, Yellow River and Hai River dries up in its estuary every year. In some regions, the water situation is exacerbated by the fact that rivers’ water is heavily polluted with a large amount of untreated wastewater, discharged into the rivers and deteriorating the water quality. Several regions’ groundwater is overexploited due to human activities demand, which is not met by local. Some provinces have over withdrawn groundwater, which has caused ground subsidence and increased soil salinity. So what is the situation in China? Is there a water crisis, and if so, what are the causes?This report is a review of several global water scarcity assessment methods and summarizes the findings of the results of China’s water resources to get a better understanding about the water situation. All of the methods indicated that water scarcity is mainly concentrated to north China due to rapid growth, overexploitation from rivers and reduced precipitation. Whereas, South China is indicated as abundant in water resources, however, parts of the region are experiencing water scarcity due to massive dam constructions for water storage and power production. Too many dam constructions in a river disrupts flow of the river water and pollutants are then accumulated within floodgates.Many Chinese officials and scholars believe that with economic growth comes improved environmental quality when the economy has reached to a certain of per-capita level. However, with the present water situation it is not sustainable or possible for China to keep consuming and polluting its water resources. Improvement of environmental quality does not come automatically with increased income, and policies, laws and regulations are needed in order to stop further deterioration of the environment.China’s water situation is not any news and the key factor is human activities, but the question is how to solve it. China’s water crisis is much more complex than over exploitation of groundwater and surface water. There are three water issues in China: “too much water – floods, too little water – droughts, and too dirty water – water pollution” (Jun & Chen, 2001). Thus, solving China’s water crisis is a huge challenge to solve without negatively affecting the economic growth.