Evaluation of groundwater sustainability based on groundwater age simulation in the Zhangye Basin of Heihe River watershed, northwestern China

Water resources, as the primary limiting factor, constrain the economic and social development in arid inland areas. The Zhangye Basin is a representative area of inland river basins, which is located in the middle parts of the Heihe River watershed, northwestern China. Facing with the huge water shortage, people exploited ground- water at a large scale in recent years. The reducing recharge from surface water and over-exploitation of ground- water led to the decline of groundwater levels and threatened the sustainability of water resources. This study con- structed a conceptual and numerical groundwater flow model and calibrated the model based on the observed wells A solute transport model was built using MT3DMS to calculate the groundwater age distribution in the Zhangye Basin. The simulated result shows that the youngest groundwater is distributed near the most upstream areas in the model domain, which is less than 1,000 a, older groundwater is distributed in deeper parts of the aquifer and near the discharge outlets, ranging from 6,000 a to over 20,000 a. Spatial variation of groundwater ages in the middle area indicates the recharge diversity between unconfined and confined aquifer. Groundwater age can serve as an indicator to evaluate groundwater＇s renewal capacity and sustainability. The formation of groundwater resources in the lower stream area would spend 10,000 a or even more than 20,000 a, so exploitation of groundwater in these areas should be restrained.

Measurement and assessment of water resources carrying capacity in Henan Province, China

As demands on limited water resources intensify, concerns are being raised about water resources carrying capacity（WRCC）, which is defined as the maximum sustainable socioeconomic scale that can be supported by available water resources and while maintaining defined environmental conditions. This paper proposes a distributed quantitative model for WRCC, based on the principles of optimization, and considering hydro-economic interaction, water supply, water quality, and socioeconomic development constraints. With the model, the WRCCs of 60 subregions in Henan Province were determined for different development periods. The results showed that the water resources carrying level of Henan Province was suitably loaded in 2010, but that the province would be mildly overloaded in 2030 with respect to the socioeconomic development planning goals. The restricting factors for WRCC included the available water resources, the increasing rate of GDP, the urbanization ratio, the irrigation water utilization coefficient, the industrial water recycling rate, and the wastewater reuse rate, of which the available water resources was the most crucial factor. Because these factors varied temporally and spatially, the trends in predicted WRCC were inconsistent across different subregions and periods.

Emergency Plan for Water Supply in Consecutive Droughts and Sustainable Water Resources Management in Beijing

Beijing, the capital city of China, has suffered from acute water shortage, with only 300 m3/a of water resources available per capita. In addition, Beijing has experienced a prolonged period of consecutive droughts from 1999 to 2010. Water crisis has constrained the socio-economic development of Beijing. Meanwhile, the national "South-to-North Water Transfer"（STNWT） project, which is expected to provide some relief to the water crisis in Beijing, is still under development. In order to ensure the security of water supply in Beijing before the completion of the STNWT project, several measures have been implemented to cope with droughts, including pumping groundwater from emergency well fields,water saving, recycling of water, rain and flood water harvesting, and the diversion of water from neighboring rivers and groundwater basins. Groundwater from four emergency well fields contributes the most to the public and domestic water supplies in Beijing, supplying a total volume of 1.8×10;m;.The water crisis is supposed to be mitigated by the completion of the STNWT project. After the completion of this project, more sustainable management of water resources will be implemented,including the use of aquifers as groundwater reservoirs and conjunctive use of surface water and groundwater resources.

Research progress of socio-economic water cycle in China

China has made great progress in the study of socio-economic water cycle. She has completed national water resources appraisement and medium to long-term water supply planning. She has been engaging in study on water-deficient regions in North China and Northwest China for about half a century. For solving water shortage problem in northern China, she has put forward the famous South-to-North Water Transferring Projects, which has been set as one of the four biggest national projects in the Tenth Five-Year-Plan period although there are still debates. For promoting water use efficiency, China has been reforming her water management system, including water right system and water price system. There has already been a case of water right purchase. China has also done a lot of research on the interaction between human activity, water and ecosystem. For meeting the need of sustainability and coordinating water resources development and environmental protection, the study of ecological water requirement became very hot in recent years. There are three focuses of socio-economic water cycle study now in China: water transfer projects from the south to the north, water resources management and ecological water requirement.

Operating mechanism and set pair analysis model of a sustainable water resources system

There is no altemative to the world＇s water resources, and their increasing scarcity is making it difficult to meet the world population＇s water needs. This paper presents a sustainable water resources system （SWRS） and analyzes the operating mechanism that makes it possible to evaluate the status of such a system. A SWRS can be described as a complex coupling system that integrates water resources, social, economic and ecological systems into a whole. The SWRS＇s operating mechanism is composed of dynamic, resistance and coordination components, and it interacts with and controls the system＇s evolution process. The study introduces a new approach, set pair analysis theory, to measure the state of a SWRS, and an evaluation index system is established using the subsystems and operating mechanism of a SWRS. The evaluation index system is separated into three levels （goal level, criteria level and index level） and divides the index standard into five grades. An evaluation model of the SWRS based on set pair analysis theory is constructed, and an example of SWRS evaluation in Shanghai is presented. The connection degrees of the index in the three levels are calculated, and the connection degree of the goal index is calculated to be 0.342, which classifies the city＇s SWRS condition as grade 2. The sustainable use of water resources in the region is determined to be at a relatively adequate level that meets the requirements of sustainable development.

Sustainable Water Resources Management: River Basin Modelling and Decision Support Framework

Sustainability is a key objective of water resources management and this paper describes a modelling and decision support framework that achieves this, illustrated by applications on the UK Thames and Mekong river basins. The decision support framework contains several modules, including an interactive user＇s interface linked to a GIS, a geo-database, knowledge base, simulation models and optimization procedures. Based on the analysis of scenarios and proposed interventions, efficient modelling and optimization tools form a comprehensive integrated decision support framework for the analysis and operational management of water resources in the river basin, our emphasis has been on a practical implementation through careful screening of alternatives, consideration of the institutional framework and direct involvement of stakeholders in the decision making process. Operating in this environment is transparent, reproducible and auditable, securing the trust of all interested parties. This paper discusses its applications to water utilisation on the Mekong river basin and drought management of the Lower Thames stored reservoir system.