An Integrated Analysis of the Eutrophication Process in the Enxoé Reservoir within the DPSIR Framework

Abstract

The Enxoé reservoir in southern Portugal has been exhibiting the highest trophic state in the country since its early years of operation. The problem has attracted water managers’ and researchers’ attention as the reservoir is the water supply for two municipalities. Extensive research was thus conducted over the last few years, including field monitoring and modelling at the plot, catchment, and reservoir scales. This study now frames all partial findings within the Driver-Pressure-State-Impact-Response (DPSIR) framework to better understand the eutrophication process in the Enxoé reservoir. Agriculture and grazing were found to have a reduced role in the eutrophication of the reservoir, with annual sediment and nutrient loads being comparably smaller or similar to those reported for other Mediterranean catchments. Flash floods were the main mechanism for transporting particle elements to the reservoir, being in some cases able to carry up three times the average annual load. However, the main eutrophication mechanisms in the reservoir were P release from deposited sediment under anoxic conditions and the process of internal recycling of organic matter and nutrients. Reducing the P load from the catchment and deposited sediment could lead to a mesotrophic state level in the reservoir. However, this level would only be sustainable by limiting the P internal load ability to reach the photic zone.

Depth profile of reservoir water quality in the Southwest of Ethiopia

“…Agriculture is frequently attributed as the main cause of surface water eutrophication. Ineffective practices cause substantial nutrient surpluses to be transmitted to water bodies through runoff and leaching [ 9 ]. Terrestrial organic matter also plays a significant role in riverine runoff [ 10 ].…”

Linking DPSIR Model and Water Quality Indices to Achieve Sustainable Development Goals in Groundwater Resources

“…The related Hydrology 2021, 8, 90 2 of 16 impacts subsequently encourage scientists, policymakers and stakeholders to respond (R) indirectly or directly to the environmental status [3]. In order to generate a clear picture of threats against soil and water resources, many researchers have applied the DPSIR model [5][6][7][8][9][10][11][12]. Recent developments in the application of the DPSIR framework include research topics related to: (a) a pressure-oriented water quality monitoring approach to ecological river restoration [5]; (b) the support of water governance [6]; (c) integrated analysis of the eutrophication process in a water reservoir [7]; (d) an investigation of the drivers related to agricultural activities leading to nitrogen pressures on water [8]; (e) identification of socio-ecological stressors affecting aquatic ecosystems in semi-arid countries [9]; (f) a sustainability assessment of water resources in Beijing (China) [10]; (g) implementation of a comprehensive evaluation model of regional water resource carrying capacity [11]; and (h) the evaluation of hydrologic characteristics of streamflow [12].…”

“…Moreover, they reported that an ecology-based pressure-oriented water quality monitoring system might contribute to restoration plans and water quality management [5]. The DPSIR framework is also applied to quantify the importance of various water quality factors in reservoirs and propose mitigation measures [7].…”

Some Observations on Phytoplankton Community Structure, Dynamics and Their Relationship to Water Quality in Five Santiago Island Reservoirs, Cape Verde

“…Dams have been used as important strategies to face water scarcity in regions where this resource needs to be stored for human development. In this situation, arid, semi-arid, and Mediterranean regions stand out since reservoirs have provided valuable services such as drinking water supplies, hydropower, and irrigation [1][2][3][4].…”