In water-stressed agricultural regions, reuse of reclaimed water has emerged as a promising alternative that improves supply reliability, alleviates water scarcity and contributes to circular economy. The European Union has recently launched several initiatives to facilitate the adoption of water reuse for irrigation. However, its adoption is still far below its potential in most areas. This is the case of the Western La Mancha aquifer, in central Spain, where reclaimed water reuse is considered an alternative source to groundwater that may contribute to reduce overexploitation. A stakeholder-based Fuzzy Cognitive Map (FCM) was developed to provide insights into the current situation of reclaimed water reuse in this area, as well as to explore the outcomes of different simulated scenarios (cost recovery, agricultural transformation, social awareness and political will increase). The FCM-based dynamic simulations showed that political will increase would generate the highest increase of reclaimed water reuse in agriculture in the study area, providing the highest increase of water reuse in agriculture. Agricultural extensification and increased social awareness delivered similar positive outcomes, however, only public awareness campaigns would increase water reuse, with agricultural extensification outcomes being more oriented towards the reduction of water abstractions and pollution. The cost recovery scenario was the only one that resulted in non-desired changes, mainly caused by reduced farmers’ income due to higher costs of reclaimed water. Finally, the analysis also evidenced the key role that the newly enacted EU Water Reuse Regulation may play in promoting reclaimed water use, even reversing the negative outcomes of the cost recovery scenario.
Anthropic pressure deteriorates river water quality, so authorities need to identify the causes and define corrective action. Physically based water quality models are a useful tool for addressing physico-chemical pollutants, but they must be calibrated with an amount of data that is often unavailable. In this study we explore the characterization of a model to design corrective intervention in the context of sparse data. A calibration indicator that is both A c c e p t e d M a n u s c r i p t 2 simple and flexible is proposed. This approach is applied to the Middle Tagus Basin in central Spain, where the physico-chemical concentration of pollutants is above legal standards. We quantify the effects of the main existing pressures (discharge from wastewater treatment plants, agricultural diffuse pollution and a major inter-basin water transfer) on the receiving waters. In particular, the study finds that wastewater treatment plant effluent concentrations should be reduced to up to 0.65 mg/L of ammonium and 0.55 mg/L of phosphate to achieve the environmental goals. We propose and prioritize a set of policy actions that would contribute to the good status of surface water bodies in the region.
<p>Continental water ecosystems and human water uses may be jeopardized by degradation of water quality. &#160;To prevent this degradation, the maximum concentration of pollutants for freshwater bodies may need to be set in the legislation. In some cases, the actions needed to achieve those environmental objectives may be technically challenging or financially overburdening. In the case of the European Union (EU), the Water Framework Directive (WFD, Article 4) requires the achievement of the good status of water bodies but allows for the declaration of exemptions due to lack of technical feasibility or disproportionate costs. Twenty years after the WFD approval, the conditions to declare exemptions remain unclear and in practice their declaration &#160;is highly discretional.</p><p>The extant scientific literature suggests several methods to formulate the justification of exemptions. Although the methodologies are diverse, they all require to select a threshold (e.g. in terms of cost disproportionality) above which a relaxation of the environmental objectives may be accepted. This threshold should be uniform across the EU River Basin Districts in order to guarantee a fair distribution of efforts across Member States. To date, however, there are very few studies that compare the application of exemptions in different regions to assess the uniformity of approaches to the declaration of exceptions.</p><p>When defining actions to achieve the good status of water bodies, the quantification of the different pressures, their interactions and the effects on receiving water bodies can be challenging. In the case of physico-chemical pollutants, however, it can be easier to define policy actions as pressures can be quantified (point loads of wastewater treatment plants, diffuse loads emanated by different land uses) and the evolution in receiving waters can be modelled.</p><p>In our research, we analyzed over one thousand water bodies in the River Basin Districts of five different Member States of the European Union (Estonia, a transboundary Ireland-United Kingdom basin, Italy, Spain and Portugal), using the available databases on Digital Elevation Models (Copernicus EU-DEM), land use (CORINE land cover), urban pressures (European Urban Wastewater Treatment Directive dissemination platform and reported data), runoff and gauged flows (Water Information System for Europe, national gauging networks) and WFD exemption databases. Each water body was characterized according to the level of nitrogen and phosphorus pressures deriving from point and diffuse loads, and the declaration of exemptions to the environmental objectives for those nutrients. The exemption threshold is assessed for each River Basin District, allowing for a critical review of the different water policies in this significant aspect of the Water Framework Directive implementation.</p>
Water reuse is a strategic priority for Water Authorities in Europe to reduce the pressure on water resources. However, its implementation is lagging behind expectations largely due to financial concerns. In this context, there is a special interest to identify in which specific Wastewater Treatment Plants it would be interesting to add a Water Regeneration Plant, taking account of potential existing clients in the vicinity and the implied costs and benefits. This paper proposes a methodology to quantify the infrastructure and operation costs of project implementation, and the benefits generated by the additional water offer. An algorithm designs the distribution network, allowing for a quick infrastructure cost analysis. The methodology is applied to the Upper Guadiana in Central Spain, where irrigation led to the overexploitation of the local aquifers and the subsequent restrictions on water use. Taking account of the existing Wastewater Treatment Plants, candidate reuse projects are classified according to their benefit/cost ratio, showing large differences according to the location and potential use of the regenerated water. The methodology allows for a quick assessment of the costs and benefits implied in different reuse projects and scenarios, providing science-based evidence to support water policy decisions.
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