Water issues and prospects for hydrological science in China

As a country with one of the world＇s most rapidly developing economies, China is home to wonderful opportunities for its people and the nation as a whole. An essential element for continued economic prosperity is a water supply of guaranteed quality and quantity, providing critical insurance for food safety, health, and political stability. However, China＇s economic success has come with serious water resources problems, intensified by human activities and climate change. The nation is now facing extreme levels of water pollution, soil erosion, and sedimentation, along with floods, droughts, and urban storms. Taken together, these impacts have provided a serious headwind to socioeconomic development in China. This article discusses the problems and emerging opportunities for the coming generation of water scientists and engineers.

Evaluation of Social Perception on Water Issues in Cameron Highlands （Malaysia） by Principle Factor Analysis

Dealing with water resources issues requires understanding of the community perception. It is important to create a communicative partnership between community and government towards sustainable water resources management. Opinion survey is an essential step to gather the point of view from local community. However, it always generates a large and complex dataset that are difficult to be interpreted by decision maker. In order to overcome this difficulty, statistical methods are applied to develop an interpretability model for decision maker. This study demonstrated the application of Descriptive Analysis and Principle Factor Analysis （PFA） to reduce the complexity of opinion survey dataset by revealing underlying information. A total of 106 respondents were interviewed; consisting of 68 male and 38 female respondents respectively. This study first applied descriptive analysis to identify the basic score for each variable, and these variables are soil erosion （68.9%）, degradation of water quality （65.1%）, degradation of freshwater ecosystem （61.0%）, water shortage （50%）, agricultural solid waste problem （46.2%）, water borne diseases （23.6%）, illegal land clearing （21.7%）, legal land clearing （15.1%）, uncontrolled river water abstraction in upstream （54.7%））, poor solid waste management （34.0%）, low awareness of local community （61.3%）, haphazard planning and development （74.5%） and administration mistake （37.0%）. Based on the PFA result, a total of four rotated factors were extracted, representing different aspects of water related issues in Cameron Highlands. Factor 1, 2, 3 and 4 were summarised to four topics namely： （1） water environment degradation caused by illegal solid waste disposal and low awareness of community, （2） agricultural development leading to negative impacts on water resources such as water shortage and ecosystem deterioration, （3） land clearing activity leading to serious land erosion （4） human health problem due to e-coli bacterial pollution and administration mistake on land development in Cameron Highlands.

The Basin Water Resources Management System and Its Innovation in China

Water provides the origin of human survival and prosperity,and the basic resource for the maintenance of terrestrial eco-systems,their biodiversity,productivity and ecological services.With China’s recent,rapid growth both in population and economic development,the water shortage has become one of the most constraints on its ecological restoration and socio-economic development,especially in the arid inland regions of northwest China.At first glance,this water shortage in China appears to be a resource crisis.But second,an in-depth analysis reveals that the water shortage crisis arises mainly resulting from the poor water management system and operating mechanism that cannot facilitate fair allocation and efficient utilization of water resources both regionally and nationally and thus is viewed as a crisis of water manage-ment.The solution of China’s water shortage and low-efficient utilization problem will,in particular,require a fundamen-tal and substantial reform or innovation of the existing water management system and operating mechanism.In this paper,we address explicitly the problems existed in the current water management system,explore the basic theory of water re-sources management and provide some insights into the way how to establish a river basin based integrated water re-sources management system in China.

Urban water system theory and its model development and application

The urban water system theory is an extension of the basin water system science on an urban scale, providing a new systematic solution for the unbalanced human-water relationship and severe water challenges, such as waterlogging, black and odorous water, and ecological degradation caused by urbanization. Most existing studies on urban water systems have focused on individual water cycle processes linked with water supply and sewage treatment plants, but mutual feedback between the water cycle and its associated material circulation and water ecology, as well as human processes, still needs further exploration. In this paper, the concept, theory, and technical methodology of the urban water system were developed based on the water cycle and basin water system science. The Urban Water System 5.0(UWS 5.0) model was developed by integrating the Time Variant Gain rainfall-runoff Model with Urban water system(TVGM_Urban) in different underlying surface conditions for analyzing the natural-social water cycle processes and their associated water environmental and ecological processes and the influence of multiscale sponge measures. Herein, five major simulation functions were realized: rainfall-runoff-nonpoint source pollutant load,water and pollutant transportations through the drainage network system, terminal regulation and purification, socioeconomic water cycle, and water system assessment and regulation. The location for the case study used in this paper was Wuhan City. The findings showed that the entire urban water system should consider the built-up area and its associated rivers and lakes as the research object and explore the integrations among the urban natural-social water cycle and river regulations inside and outside of the city as well as the effects of socioeconomic development and sponge measures on the water quantity-quality-ecology processes. The UWS 5.0 model efficiently simulated the urban rainfall-runoff process, total nitrogen(TN) and total phosphorus(TP) concentrations in water bodies, and characteristic indicators of socioeconomic development. For the rainfall-runoff simulations, the correlation coefficient and Nash-Sutcliffe efficiency(NSE) fall under the excellent and good classes, respectively. For the TN and TP concentration simulations, results exhibited good bias and the correlation coefficients exceeded 0.90 for 78.1% of the sampled sites. The simulation of 18 socioeconomic indicators provided excellent bias, correlation coefficient, and NSE values of 100%, 83.3%, and 69.4% to total indicators, respectively. Based on the well-calibrated UWS 5.0 model, the source sponge,artificial enhancement, and source reduction-path interception-terminal treatment measures were optimized, which considerably mitigated waterlogging, black and odorous water, and lake eutrophication, respectively. The mitigation performance revealed that the maximum inundated area for a once-in-10-year rainfall event was reduced by 32.6%, the removal ratio of the black and odorous water area was 65%, the comprehensive trophic state index of water bodies was reduced by 37%, and the green development level of Wuhan City in 2020 increased from 0.56 to 0.67. This study is expected to advance the intersection and development of multidisciplinary fields(e.g., urban hydrology, environmental science, and ecology) and offer an important theoretical and technical basis for solving urban complex water issues and promoting green development of cities.