An Ecological Network Analysis Based Approach For Assessing Water Use Systems Sustainability

To meet the demands of an ever-increasing population and growing economic production, societies extract large quantities of water from rivers, lakes, wetlands and underground aquifers. As such, water scarcity problems have intensified and have emerged as a crucial environmental problem at the international scale. To sustain the benefits accrued to society and the economy from increased access to water, the sustainability of water use systems must be guaranteed. For water use systems, as all of the water use sectors directly and indirectly depend on and are affected by the other sectors, careful consideration of their interlinkages and dynamics is necessary. Thus, there is a need to treat social, economic and environmental aspects as an integrated one for sustainabiiity quantification, and a systems approach is therefore required to be addressed.Ecological network analysis (ENA) is a systems-oriented methodology, and it has been used in water use systems for a better understanding of water use sustainability. In this study, in order to asess water use sustainability, we develop our earlier optimal balanced water use network structure theory for measuring the sustainability of water use further; we address its shortcomings and propose a conceptual model and two new indicators to evaluate sustainability. We then combine the new indicators with a conventional composite indicator system to obtain an improved assessment of the sustainability of a water system. This new conceptual model and indicators builds on the metric of the distance between the optimal sustainable water use state and the present water use state. The new indicators can evaluate the ability of a water use network to transform and use water resources, and to adapt to stresses and changes. The new model is an example of how network efficiency and resilience can be incorporated into indicators of sustainability.A case study to test the proposed methodology is explored, using the four sub-basins of the Huaihe River during periods of2005-2011as our study site. In the case study, we calculated the balanced water use network structure and the present network structure, and then we quantified the distance between the optimal and present water use through the proposed two indicators to assess its sustainability of water use level. Also, we assessed sustainable water use in the study areas using specific conventional composite indicators. We then added the proposed new indicators to the conventional composite indicators to assess the sustainability. Finally, we compared and discussed the results computed from the three methods. We conclude with a summary of the key results, and suggest directions for future research.