Yizi Shang

Temporal and spatial characteristics of pan evaporation trends and their attribution to meteorological drivers in the Three-River Source Region, China

Pan evaporation is an important indicator of atmospheric evaporative demand, and its long-term variation is of much concern in studies of climate change. Based on data from 33 meteorological stations from 1962 to 2012, this work considered the temporal and spatial trends of pan evaporation and the meteorological variables that affect them in the Three-River Source Region (TRSR) of southwestern China. Pan evaporation in the TRSR has decreased significantly since 1988 with an obvious abrupt change from 1993 to 2003. Furthermore, a 27 year period of oscillation has existed over the past 51 years. Pan evaporation reflects the combined effects of four meteorological variables: net radiation (Rn), wind speed (u2), actual vapor pressure (ea), and air temperature (Ta). Based on this research, a number of conclusions were drawn. (1) The pace of climate change increased after 1980 and pan evaporation decreased at a rate of −13.3 mm/a2 from 1980 to 2012, which is much faster than the rate of −1.2 mm/a2 from 1962 to 1979. (2) For the decrease of pan evaporation from 1980 to 2012, the quantifying contributions of Rn, u2, ea, and Ta were −8.7, −6.4, −1.8, and +3.6 mm/a2, respectively. Thus, it was established for the TRSR that “global dimming” was the main reason, and “wind stilling” was a close second to global dimming for the decrease in pan evaporation. (3) Different regions of the TRSR are affected differently by the effects of the meteorological variables. Low-elevation regions in the TRSR are more susceptible to the effects of net radiation and wind speed, whereas high-elevation regions are affected more by actual vapor pressure and air temperature.

Beijing's Water Resources: Challenges and Solutions

Beijings local water resources have been overexploited and the ecological and environmental pressures exceed the carrying capacity of this densely populated megacity. This article examines the current status of Beijings water resources with respect to its industrial, residential, and eco-environmental water usage and the challenges it may face in the near future. The article describes the context of water uses, the steps taken by Beijing to alleviate the water shortage problems, and challenges to Beijings abilities to meet its urgent and future water needs. A multipronged strategy is proposed that aims at both the present problems and the anticipated future challenges. In particular, engineering and institutional approaches for Beijings successful transition from overexploitation to sustainable utilization of water resources are explained. Actions include reasonable water utilization, water conservation, reclaimed wastewater, and importing water from neighboring areas. We conclude that Beijing must take additional steps in water resource management to ensure its sustainable development that involves continued urbanization sprawls and population growth. Future water resource management strategies should focus on strengthening water demand management through water conservation, efficient interbasin water transfers, use of nontraditional water resources, strategically reserving water supply, and promoting rehabilitation of the eco-environments.

An analysis of the factors that influence industrial water use in Tianjin, China

Abstract This study identifies the driving forces behind maximizing Tianjin’s industrial water use efficiency in China. For this purpose, a decomposition method is developed to quantify the degree of the impact of each factor. The results show that industrial expansion was responsible for an increase in annual water use of 78 million m³, while technical advances and water efficiency measures contributed annual water savings of about 76 million m³. Further, the results highlight that Tianjin has not considered the rise in water efficiency to be the primary goal of restructuring local industries over the past decade.

Flash Flood Early Warning Research in China

Abstract Flash floods cause extensive loss of property and human life. Early warning systems present a more efficient approach to flood prevention and mitigation than engineering measures. This article reviews research on flash flood early warnings in China, including long-term prediction methods based on statistical regularity and flood mechanisms, and real-time warning indicators relying on multi-source data and automated systems. Current research shortcomings are discussed, and suggestions for future improvements are proposed. This research can provide public officials with knowledge of flash flood early warnings, influencing policy and protecting people from flash flood disasters.

China’s campaign to create artificial water surfaces in drought-affected regions must consider prevention measures for ecological problems

Many new cities have developed in China in recent years and older cities have expanded substantially. These newly built urban areas incorporate vast expanses of water landscapes for aesthetic purposes and enhance the quality of the living environment. Considering the uneven distribution of water resources in China, concerns have been raised over the impact of creating such large-scale water surfaces on ecosystems of the country’s northern arid region. The methods for creating surface water bodies in the arid cities of northern China are examined and the internal driving factors are analyzed. The authors advocate that these cities should exercise caution when creating artificial water landscapes and that such projects must be scientifically sound.

Assessing emergency regulation technology in the Middle Route of the South-to-North Water Diversion Project, China

Abstract The Middle Route of the South-to-North Water Diversion Project is important for China. Any sudden water pollution accident along the route would threaten normal water supply. We studied four technologies (hydrodynamic and water quality simulation, source identification, emergency regulation, and evaluation of emergency measures) and developed and implemented a decision support system that provides technical support in managing pollution accidents. The achievements, which include four technologies and a system, have practical significance for emergency management in the Middle Route as they can help deal with accidents and policy formulation, and can be applied to other water transfer projects.

Sudden water pollution accidents and reservoir emergency operations: impact analysis at Danjiangkou Reservoir

ABSTRACT Danjiangkou Reservoir is the source reservoir of the Middle Route of the South-to-North Water Diversion Project (MRP). Any sudden water pollution accident in the reservoir would threaten the water supply of the MRP. We established a 3-D hydrodynamic and water quality model for the Danjiangkou Reservoir, and proposed scientific suggestions on the prevention and emergency management for sudden water pollution accidents based on simulated results. Simulations were performed on 20 hypothetical pollutant discharge locations and 3 assumed amounts, in order to model the effect of pollutant spreading under different reservoir operation types. The results showed that both the location and mass of pollution affected water quality; however, different reservoir operation types had little effect. Five joint regulation scenarios, which altered the hydrodynamic processes of water conveyance for the Danjiangkou and Taocha dams, were considered for controlling pollution dispersion. The results showed that the spread of a pollutant could be effectively controlled through the joint regulation of the two dams and that the collaborative operation of the Danjiangkou and Taocha dams is critical for ensuring the security of water quality along the MRP.

Remote sensing of water quality based on HJ-1A HSI imagery with modified discrete binary particle swarm optimization-partial least squares (MDBPSO-PLS) in inland waters: A case in Weishan Lake

Abstract Remote sensing has been recognized as an effective tool to monitor water quality in inland waters. An adaptive model coupled with a modified discrete binary particle swarm optimization algorithm utilizing the catastrophe strategy and partial least squares (MDBPSO-PLS) was developed to retrieve the water quality indexes (chlorophyll a (chl-a), total suspended matter (TSM), and turbidity) in Weishan Lake. Based on the selective bands for water quality retrieval, the proposed MDBPSO algorithm was compared with original DBPSO and Genetic Algorithm (GA) in order to validate the feasibility and efficiency of the proposed algorithm. The comparison results indicated that MDBPSO with the catastrophe strategy could avoid the premature convergence phenomenon of DBPSO algorithm. The hyperspectral data from HJ-1A Hyperspectral Imager (HSI) selected by MDBPSO were utilized to establish the PLS model by correlating the spectral data with measured water quality parameters. Then the established PLS model was compared with the PLS model established with full spectral data and measured water quality parameters. MDBPSO-PLS showed the better performance in retrieving the above-mentioned three parameters in Weishan Lake. The comprehensive errors between measured and retrieved parameters in MDBPSO-PLS (chl-a (R2 = 0.97, CE = 3.16%), TSM (R2 = 0.97, CE = 5.84%), and turbidity (R2 = 0.97, CE = 7.40%)) were lower than those in PLS model (chl-a (R2 = 0.55, CE = 18.71%), TSM (R2 = 0.49, CE = 49.50%), and turbidity (R2 = 0.50, CE = 50.46%). The three water quality parameters were mapped by using MDBPSO-PLS. Our observations indicated that the MDBPSO-PLS model showed the significantly higher retrieval accuracy than the PLS model and could provide realistic information on the distribution of chl-a, TSM, and turbidity in Weishan Lake based on HJ-1A HSI.

Hierarchical prediction of industrial water demand based on refined Laspeyres decomposition analysis

A recent study decomposed the changes in industrial water use into three hierarchies (output, technology, and structure) using a refined Laspeyres decomposition model, and found monotonous and exclusive trends in the output and technology hierarchies. Based on that research, this study proposes a hierarchical prediction approach to forecast future industrial water demand. Three water demand scenarios (high, medium, and low) were then established based on potential future industrial structural adjustments, and used to predict water demand for the structural hierarchy. The predictive results of this approach were compared with results from a grey prediction model (GPM (1, 1)). The comparison shows that the results of the two approaches were basically identical, differing by less than 10%. Taking Tianjin, China, as a case, and using data from 2003-2012, this study predicts that industrial water demand will continuously increase, reaching 580 million m3, 776.4 million m3, and approximately 1.09 billion m3 by the years 2015, 2020 and 2025 respectively. It is concluded that Tianjin will soon face another water crisis if no immediate measures are taken. This study recommends that Tianjin adjust its industrial structure with water savings as the main objective, and actively seek new sources of water to increase its supply.

Influence of Daily Regulation of a Reservoir on Downstream Navigation

AbstractDaily flow regulation of a hydropower station has a greater influence on waterway transport than long-term regulation such as seasonal or annual regulation. Although a physical model can re...