Assessillg Water Scarcity Based On The Concept Of Water Footprint

There are growing concerns about unsustainable use of freshwater resources and conflicts between wa-ter demand and supply. Water problem has been a main constraint for future socio-economic develop-ment among many regions. Traditional methods of water scarcity assessment are mainly based on water quantity, and there is a lack of an approach that considers both water quantity and quality. Water foot-print, as an analytical tool that can describe the relationship between human activities and water scarcity, offer an innovative approach to integrated water resources management.Based on water footprint concept, this study introduced water quantity and quality scarcity indices and developed a simple approach to assess water scarcity integrating water quantity and quality. To illus-trate the approach, we choose Beijing, the Heihe River Basin and China as our study areas and assessed water scarcity at different levels.The main findings of this study are shown below:(1) The water scarcity index remained at a high value of3.5with a water quantity and quality scarcity index of1.2and2.3in2009(exceeding the thresholds of0.4and1, respectively), thus Beijing is char-acterized by serious quantity-and quality-induced water scarcity. Beijing made a huge progress in mit-igating water scarcity betweenl999and2009. The water quantity and quality scarcity index decreased by59%and62%, respectively. These achievements were made through great efforts of water-saving measures and wastewater treatment. Despite this progress, as a result of unsustainable water use and pollution, groundwater levels continued to decline, and water quality showed a continuously deteriorat-ing trend.(2) The Heihe River Basin was suffering from serious water scarcity during2004-2006, with a water quantity and quality scarcity index of1.3and1.6, respectively. Annual blue water footprint of the Heihe River Basin between2004and2006was8.11×108m3yr-1,and green water footprint was9.56×108m3yr-1, while grey water footprint was42.22×108m3yr-1. Agricultural production was the largest water consumer and the biggest sector of water pollution. It’s found that the environmental flow requirements are not met during two thirds of a year and this leads to unsustainable water use, causing several eco-logical problems.(3) Water scarcity condition of10river basins and31provinces in China had been assessed during2007-2009. From river basin perspective, there were4river basins had quantity-and quality-induced water scarcity problems,1river basin only had water quantity scarcity problem,4river basins only had water quality scarcity problem and1river basin was not confronted with water scarcity problem. From province perspective, there were14provinces had quantity-and quality-induced water scarcity prob-lems,10provinces only had water quality scarcity problem and7provinces was not confronted with serious water scarcity problem.Our research also demonstrates that as a tool to analyze water consumption and pollution, water foot-print is able to qualified water problems in different scales. The assessing approach of water scarcity integrating water quantity and quality we developed can be easily used in water scarcity assessment regardless graphic limitations, so as to provide theoretical support for better water resources manage-ment. When making water resources management policy, conditions of different river basins and pollu-tants should be taken into consideration in order to water resources protection and waste water disposal. Measures should also be taken to reduce grey water footprint below available water resources.