Water-Sediment Physicochemical Dynamics in a Large Reservoir in the Mediterranean Region under Multiple Stressors

Abstract

Nowadays, the Mediterranean freshwater systems face the threat of water scarcity, along with multiple other stressors (e.g., organic and inorganic contamination, geomorphological alterations, invasive species), leading to the impairment of their ecosystem services. All these stressors have been speeding up, due to climate variability and land cover/ land use changes, turning them into a big challenge for the water management plans. The present study analyses the physicochemical and phytoplankton biomass (chlorophyll-a) dynamics of a large reservoir, in the Mediterranean region (Alqueva reservoir, Southern Portugal), under diverse meteorological conditions and land cover/land use real scenarios (2017 and 2018). The most important stressors were identified and the necessary tools and information for a more effective management plan were provided. Changes in these parameters were further related to the observed variations in the meteorological conditions and in the land cover/land use. The increase in nutrients and ions in the water column, and of potentially toxic metals in the sediment, were more obvious in periods of severe drought. Further, the enhancement of nutrients concentrations, potentially caused by the intensification of agricultural activities, may indicate an increased risk of water eutrophication. The results highlight that a holistic approach is essential for a better water resources management strategy.

The Use of Sentinel-3/OLCI for Monitoring the Water Quality and Optical Water Types in the Largest Portuguese Reservoir

“…However, there are periods and areas of the reservoir (mainly the northern region of the reservoir, between Monsaraz and Lucefecit-see Figure 17) with the presence of high Chl-a and cyanobacteria concentrations. This conclusion is in line with results from previous works [30,64,65] identifying the northern area as the key area for the emergence of microalgae…”

Automated Monitoring of a High-Speed Flocculation Flat-Bottomed Sludge Blanket Clarifier Pond during Drought and Flood Conditions

“…To ascertain whether the raw water in a reservoir is polluted by heavy metals, the Sediment Quality Guidelines can be used to analyze sediment toxicity and pollutants in the water column [4,5]. Palma et al [6] used land use/land cover changes to explain nutrient and organic matter concentrations in reservoirs, thereby providing guidance for water management policies to reduce surface water pollution. In many countries, large amounts of resources have been dedicated to the elimination of pollution sources.…”

The Physicochemical Properties of Deposited Sediments at the Maruba Dam Reservoir Inlet, Machakos County, Kenya

“…e availability of water in the right quantity and quality is a serious challenge that engulfs many water resources, especially in developing countries [1,2]. e scarcity of water triggers the actions of related problems, for instance, degradation and abstraction [3]. e available freshwater resources in developing countries are unable to meet the huge demand for water in domestic, agricultural, and industrial operations [4].…”

“…Reservoirs, therefore, play an important economic role, which sorely depends on the water storage capacity [8][9][10]. However, reservoir operations are often subjected to recurring stresses associated with huge water demands from the rising human population and agricultural activities [3,11,12]. e problems are further compounded by climate change uncertainties [4,13].…”