Evolution trend of the water quality in Dongping Lake after South-North Water Transfer Project in China

To investigate the evolution trend of water quality in Dongping Lake after South-North Water Transfer Project operation as well as to ensure the safe usage of the water receiving areas, water samples were collected and determined before and after water delivery in different hydrological seasons. Then, comprehensive pollution index method, comprehensive nutrition state index method and health risk assessment model were utilized to evaluate the quality, nutrition, and health risk of Dongping Lake water. Results showed that the quality of Dongping Lake water still met level Ⅲ (light pollution) no matter before or after water delivery. The nutrition state was improved from light eutropher before water delivery to mesotropher after water delivery. The health risk level was reduced from high-medium before water delivery to medium level after water delivery. In summary, the operation of the eastern route of South-North Water Transfer Project is beneficial for water environment improvement of Dongping Lake.

Eco-environmental benefit assessment of China's South-North Water Transfer Scheme——the middle route project

This paper assess the eco-environmental benefits that may come from the middle route project of China's South-North Water Transfer Scheme(SNWT) with principles and methods of eco-economics and planning reports of SNWT's middle route project. Some benefits were calculated in monetary units. To make sure that the results can be comparable with normal monetary indices, concrete assessment objects and the parameters are prudently selected according to the major characteristics of the project and its water import region. Primary assessment revealed that in different project construction stages, the benefit could be more than 13 07 billion RMB Yuan in 2010 and 19 79 billion RMB Yuan in 2030, respectively. The monetary value tends to increase with social-economic development. To realize these potential benefits, however, calls for more endeavors.

Estimating minimum ecological water required of the western route first stage project of China＇s south-to-north water transfer scheme for water exporting rivers

It is well known that there is abundant water resources in basin of the Yangtze River, the first largest river in China, which is mainly located in Southern China. However, water resources is very scarce in the basin of the Yellow River, which is mainly located in Northern China. So the western route project of south-north water transfer scheme （WRP-SNWTS） aims to transfer water from the Yangtze River to the Yellow River. The area of WRP-SNWT, located in the upper reaches of the Yangtze River and the main areas of Sichuan and the marginal areas of the Qinghai-Tibet Plateau, has sufficient water resources but fragile ecology and environment. Therefore, it is necessary for WRP-SNWT to analyze the ecology water required. Based on the planning principles of from low elevation to high elevation, from small to large, from short to long and from easy to difficulty, the WRP-SNWT will be constructed through three stage projects. The western route first stage project of the south-north water transfer scheme （WRFST-SNWTS） is planned to transfer 4×10^9m^3/a from six tributaries of the Yalong river and from Dadu river to Jiaqu of Yellow River.. Daqu river and Niqu river are the branches of Xianshui river. Sequ river, Duke river, Make river and Ake river are the branches of Dadu river, which account for 65-70% of the total river run-off. It need more research and the rest run-off can satisfy channel ecology water required. According to analysis ecological water required which mainly satisfy for aquicolous biology in water-exporting region, such as low air temperature. Fish and aquicolous biology main living from May to August, and rivers are iced up from December to March of next year, ecology water required mainly for fish and aquicolous biology. The flow criterion of Tennant method is modified. The ecology water required of WRFSP-SNWTS is estimated by the flow data of Zhuwo gauging station, Zhuba gauging station, Chuosijia gauging station and Zumuzu gauging station. The result show that the ecology water required calculated by modified Tennant less 1 l percent than that of Tennant. This estimating result can supply more water resources for transferring to Yellow River. Meanwhile, this can supply gist for research transferring water of WRFSP-SNWTS.

丹江河流枯水期水化学特征及离子来源分析

丹江河水水化学特征是南水北调中线水源地水质的重要指标之一。在2017年10月—2018年4月采集了丹江不同河段河水样品,研究枯水期河水中主要化学离子的质量浓度及其来源。结果表明:丹江水体中主要阳离子为Ca^(2+),主要阴离子为SO_(4)^(2-),各离子质量浓度与长江、汉江相似,唯有Mg^(2+)质量浓度高于长江、汉江水体;丹江水体表现出硝酸盐污染,且从上游到下游NO_(3)^(-)质量浓度在增加,表明人类活动对河流水质的影响在增强。丹江水离子主要来源为岩石风化,大气降水以及人类活动对丹江干流河水的水体也有一定影响。

Study on integrated calculation of ecological water demand for basin system

The operation of reservoir(s) has a certain impact on the downstream hydrologic regime,and even endangers the ecological water safety of river corridor and ecosystems which interact with river system.Therefore,ecological operation needs to be carried out in order to ensure ecological water use of downstream zone.The key technological support is the estimation and integrated calculation of ecological water demand.The connotation of the integrated calculation on ecological water demand lies on that the ecological water demand of different ecosystems is integrated to meet the requirements of water allocation and operation on watershed scale in terms of hydrological cycle.Considering the practical requirement of ecological operation of reservoir(s),this study proposed an integrated calculation approach of ecological water demand according to the ecological water demand in various ecosystems as well as the hydraulic connection among them;it established an integrated calculation model of regional ecological water demand by means of the distributed hydrological model,and studied the integrated calculation in Yalong River basin which is the source area of the west route of South-North Water Transfer Project as an example.The results indicated that the integrated calculation model more effectively combined the ecological water demand and hydraulic connection of ecosystems in time and space,compared with the lumped water balance analysis,since the former conquered the defect of insufficient ecological water source and supplement on multiple spatial and temporal scales,and met the demand of ecological operation of reservoir(s).

A new criterion for defining the breakpoint of the wetted perimeter-discharge curve and its application to estimating minimum instream flow requirements

The wetted perimeter method(WPM) is used in hydrology and hydraulics to calculate instream flows.The WPM requires few data.It requires only the values of the wetted perimeter,flow and water level,which can be obtained from the hydrologic stations of the river in question.In addition,the WPM is not limited by the impacts of human activities on the river runoff.Therefore,this method is generally suitable for the current conditions in China.However,the process of applying the WPM involves two key aspects:how to plot the curve describing the relationship between the wetted perimeter and the discharge and how to confirm the breakpoint of the wetted perimeter-discharge curve.The traditional method is to calculate the curvature or the slope of the wetted perimeter-discharge curve to obtain the minimum flow.According to this method,the minimum flow corresponds to the point of maximum curvature or to the point at which the slope of the curve is equal to 1.The wetted perimeter-discharge curve of a natural river is only part of the complete curve.Thus,the instream flow calculated by the traditional method is the minimum or maximum discharge.The new criterion for defining the breakpoint of the wetted perimeter-discharge curve is that the slope at the breakpoint is a relative maximum,the second-largest slope.The discharges at the breakpoints corresponded to the minimum flow levels required to maintain the ecological function of the river.The minimum instream flow requirements(MIFRs) of four typical reaches,Zhuba,Daofu,Ganzi and Zumuzu hydrological stations on the West Course of the First Stage Project of the South-North Water Transfer Project(WCFSPSNWTP),are calculated using an improved wetted perimeter method(IWPM).The results show that the MIFRs of Zhuba,Daofu,Ganzi and Zumuzu are approximately 9.06-14.5 m 3 s-1,20.7-43.5 m3 s-1,38.8-77.2 m 3 s-1 and 40.4-59.5 m 3 s-1,corresponding to 11.7%-33.9%,14.2%-37.6%,12.4%-28.4% and 17.5%-30.2%,respectively of the annual average flow(AAF).These MIFRs can maintain good ecological function in a river according to the criterion furnished by the Tennant method.