Creation of an environmental sustainability index for water resources applied to watersheds

One of the problems regarding water resources is the management and interactions with the environment in terms of ensuring conservation. An efficient way to assess problems arising from the interaction of water resources with management and the environment is to apply water quality indicators. In view of this, a water sustainability index for a watershed was developed. The watershed under study predominantly uses soil and water for agricultural purposes. The indicator was called water resources sustainability index (WRSI). The values range from 0 (worst condition) to 1 (best condition) based on an integration of water quality parameters, environmental sanitary conditions, and vegetation indexes analyzed by geoprocessing techniques and weighted by analytic hierarchy process. The results show that the lowest WRSI values are obtained in regions with predominantly agricultural activities and extremely poor basic sanitary conditions. Approximately 24% of the study area had WRSI values around 0.6, indicating a regular status; values above 0.9 would be desirable. Precarious conditions mean poor basic sanitary conditions and agricultural activities that, in addition to the high load of organic fertilizers, also produce a high load of sediments, causing degradation of the water environment. It is also noteworthy that urban areas, in comparison with rural areas, presented on average higher WRSI values, which is related to the population's access to better basic sanitation conditions and to low exposure to possible water contamination.