Infiltration Ponds Research Articles

Productivity Improvement of Wasteland in Drought-Prone, Overdrafted and Rocky Terrain Watershed: A Case Study of Upper Thurinjalar Watershed in Ponnaiyar Basin Tamil Nadu, India

A great extent of productive land has become wasteland due to climatic change, frequent monsoon failure and inadequate water supply for irrigation. Identification of such lands can be helpful for conversion into productive land. Present study focuses on identification of wasteland in the watershed by utilising land use map of 2018 by interpreting satellite image of IRS-P6 LISS IV over upper Thurinjalar watershed in Thiruvannamalai district of Tamil Nadu. For this purpose, digital image processing software ERDAS IMAGINE 2015 and GIS Software ArcGIS 10.5 version were used. Fifty percentage of the total geographical area of the watershed is reported as wasteland in our study. Favourable wasteland layer was superimposed upon the administrative village boundary map by GIS overlay analysis. Type of wasteland was demarcated using remote sensing and GIS techniques, and thematic layers such as lineament map, geomorphology map and depth to bedrock map were generated. Through GIS overlay analysis, wasteland map of the study area was overlaid on the three thematic layers and favourable artificial recharge sites were identified. In upper Thurinjalar watershed, 61.06 km2 is highly favourable and 214.18 km2 is moderately favourable for recharge, and the sites are recommended for groundwater recharge using structures such as pits, percolation ponds, borewells and check dams. Among wastelands, degraded lands under plantation, lands with scrub and lands without scrub were prioritised for groundwater recharge. Technique adopted in our study can be applied over other watersheds and wasteland to convert them into productive land.

Needs of Effective Water Conservation

The earth’s supply of fresh water is fixed. Its distribution is skewed spatially and temporarily. The maximum usage of water withdrawals is by agricultural sector for irrigation. It is socially, economically and culturally entwined with the lives of people. In the course of irrigation development many irrigation projects have been evolved across India. There are various irrigation techniques followed in different parts of India. The continued growth of population, industrialization, urbanization, climate change, emission of greenhouse gases and deforestation build up pressure on available water resources and arable land for food production. It is further worsened with crop production loss, deterioration of water sheds, disappearance of wetlands and reoccurrence of erratic monsoon. The fall of ground water table, deterioration of quality water, salinization, soil degradation, water logging and irrational use of water emphasized the need for conservation of irrigation water sources. While we have adopted many conservation measures like artificial recharge scheme, percolation ponds, check dams, irrigated agriculture modernization and rehabilitation works on the one side, the problem of irrigation water scarcity and shortage in the availability of quality water still persists. Hence, an attempt has been made to study the need s and effective management on conservation of irrigation water resources.

The Impact of Lake Water Quality on the Performance of Mature Artificial Recharge Ponds

Artificial groundwater recharge is commonly used for drinking water supply. The resulting water quality is highly dependent on the raw water quality. In many cases, pretreatment is required. Pretreatment improves the drinking water quality, although how and to what extent it affects the subsequent pond water quality and infiltration process, is still unknown. We evaluated two treatment systems by applying different pretreatment methods for raw water from a eutrophic and temperate lake. An artificial recharge pond was divided into two parts, where one received raw water, only filtered through a microscreen with 500 µm pores (control treatment), while the other part received pretreated lake water using chemical flocculation with polyaluminum chloride (PACl) combined with sand filtration, i.e., continuous contact filtration (contact filter treatment). Water quality factors such as cyanobacterial biomass, microcystin, as well as organic matter and nutrients were measured in both treatment processes. Microcystin condition was screened by an immunoassay and a few selected samples were examined by ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) which is a chemistry technique that combines the physical separation capabilities of liquid chromatography with the mass analysis capabilities of mass spectrometry. Results showed that cyanobacterial biomass and microcystin after the contact filter treatment were significantly different from the control treatment and also significantly different in the pond water. In addition, with contact filter treatment, total phosphorus (TP) and organic matter removal were significantly improved in the end water, TP was reduced by 96% (<20 µg/L) and the total organic carbon (TOC) was reduced by 66% instead of 55% (TOC content around 2.1 mg/L instead of 3.0 mg/L). This full-scale onsite experiment demonstrated effective pretreatment would benefit a more stable water quality system, with less variance and lower microcystin risk. From a broader drinking water management perspective, the presented method is promising for reducing cyanotoxin risk, as well as TP and TOC, which are all predicted to increase with global warming and extreme weather.

Effectiveness of check dam and percolation pond with percolation wells for artificial groundwater recharge using groundwater models

Abstract Population growth and higher living standards have resulted in ever-increasing demand for water. For the present study natural recharge was computed from a water balance model and daily water level fluctuations were measured to study the increase in water level due to artificial recharge. Numerical models were developed using MODFLOW to analyze the feasibility of different artificial recharge arrangements such as check dam and percolation pond with percolation wells individually and in combination and evaluate the effectiveness of the structures in recharging the aquifer. The maximum increase in water level was found to be 3.46 m, 2.54 m and 4.7 m respectively for the check dam, percolation pond with three percolation wells and combined structure arrangement after 2 years of artificial recharge. The zone of influence was obtained as 400 m, 600 m and 500 m respectively for the check dam, percolation pond and combined structure system. Water level fluctuations also proved the same. Water level increase obtained from the natural recharge study was only of the order of 0.2 m. Artificial recharge is found to be very effective for sustainable development of water resources and the percolation pond was found to be the most appropriate structure for groundwater recharge for the study area.

Effect of temperature variations on the travel time of infiltrating water in the Amsterdam Water Supply Dunes (the Netherlands)

Travel time is one of the important criteria in the design of managed aquifer recharge systems for securing good drinking water quality. Traditionally, groundwater travel time has been modelled without considering the effect of temperature. In this study, a cross-sectional heat transport model was constructed for the Amsterdam dune filtration system (in the Netherlands) to analyse the effect of temperature on groundwater travel times. A groundwater flow model, a chloride transport model, and a heat transport model were iteratively calibrated with measured groundwater levels, chloride concentrations, and temperature series in order to improve model calibration and reduce model uncertainty. The coupled flow and heat transport model with temperature-dependent density and viscosity provided more accurate estimation of travel times. The results show that seasonal temperature fluctuations in the source water in the infiltration pond cause temperature variations in the shallow groundwater. Viscosity is more sensitive to temperature changes and has a larger effect on groundwater travel times. Groundwater travel time in the shallow sand aquifer increases from 60 days when computed with the traditional groundwater flow model to 73 days in the winter season and 95 days in the summer season when computed with the coupled model. Longer travel time is beneficial for water quality improvement. Thus, it is important to consider the effect of temperature variations on groundwater travel times for the design and operation of managed aquifer recharge systems.

Identifying groundwater recharge zones using remote sensing & GIS techniques in Amaravathi aquifer system, Tamil Nadu, South India

In order to increase the sustainability of the wells and arrest the declining groundwater level trends in Amaravathi aquifer system, southern India, remote sensing and geographic information system (GIS) approach was attempted to identify favourable regions for construction of artificial recharge structures. GIS overlay analysis was carried out wherein 8 layers viz. geology, geomorphology, slope, soil, land use, post monsoon water level, weathering depth and waterbodies/drainage were integrated. Survey of India toposheet, Indian Remote Sensing Satellite IC data and ASTER data were used to develop the various thematic maps. These maps were later transferred to raster data. Groundwater level from the monitoring stations and weathering thickness data from the 248 deep wells constructed were used for the integration. Four zone namely very high, high, moderate and very poor have been demarcated. About 45% of the study area was categorised as high to very highly feasible zone. The existing artificial recharge structures in the region were also plotted and proposed artificial recharge structures were calculated. About 166 masonry check dam, 155 nala bunds, 575 recharge shafts (within tanks), 716 percolation ponds (repair, renovation and restoration) have been calculated and implementation of the proposed structures would create an additional water resource of 198 million m3 annually.

Multi-criteria-based approach for optimal siting of artificial recharge structures through hydrological modeling

Extensive use of groundwater and abandoned agriculture practices causing desertification and environmental degradation of ecosystem is of major concern to planners. Ecologically sensitive areas like Western Ghats in India which is identified as World Heritage Site by UNESCO is facing similar threat. Construction of suitable artificial recharge structures at appropriate location is essential to improve the groundwater resource for environment protection. Study of watershed morphology has indicated the elongated shape, low runoff, and highly permeable subsoil conditions. The study proposes integration of multi-criteria-based land suitability analysis with runoff modeling in HEC-HMS to identify suitable structures and their location for artificial recharge of ground water. Remote sensing and GIS tools were used for mapping, integration, and modeling of artificial recharge process. Results demonstrate the suitability of farm ponds along first-order streams, percolation ponds, and subsurface dykes in middle of watershed and check dams in higher-order stream network. It is concluded that improved groundwater resources facilitate better environment protection and ecological balance.

Are dominant microbial sub-surface communities affected by water quality and soil characteristics?

Subsurface microorganisms must deal with quite extreme environmental conditions. The lack of light, oxygen, and potentially nutrients are the main environmental stresses faced by subsurface microbial communities. Likewise, environmental disruptions providing an unbalanced positive input of nutrients force microorganisms to adapt to varying conditions, visible in the changes in microbial community diversity. In order to test microbial community adaptation to environmental changes, we performed a study in a surface Managed Aquifer Recharge facility, consisting of a settlement basin (two-day residence time) and an infiltration pond. Data on groundwater hydrochemistry, soil texture, and microbial characterization was compiled from surface water, groundwater, and soil samples at two distinct recharge operation conditions.Multivariate statistics by means of Principal Component Analysis (PCA) was the technique used to map the relevant dimensionality reduced combinations of input variables that properly describe the system behavior. The methodology selected allows including variables of different nature and displaying very different range values. Strong differences in the microbial assemblage under recharge conditions were found, coupled to hydrochemistry and grain-size distribution variables. Also, some microbial groups displayed correlations with either carbon or nitrogen cycles, especially showing abundant populations of denitrifying bacteria in groundwater. A significant correlation was found between Methylotenera mobilis and the concentrations of NO3 and SO4, and also between Vogesella indigofera and the presence of DOC in the infiltrating water. Also, microbial communities present at the bottom of the pond correlated with representative descriptors of soil grain size distribution.

Planting Values for Saving Groundwater through Family Education

This study aims to determine the planting values for saving groundwater through family education in Larangan Selatan sub-district of Tangerang. The research respondents were parents from 40 families in Citizen Association (RW) 10 Cileduk Tangerang. Data collection techniques using questionnaires, sampling techniques using purposive sampling. Research instruments include planting water-saving values through explanation, giving examples, reminding, direct reprimand, telling, getting used to. For observing, focus that be observed were 4 things on the house yard of respondent, were about: The provision of bio pores, rainwater infiltration ponds, the provision of land in the yard, increasing vegetation in the yard. The results of the study showed that parents carrying out educational tasks, namely instilling economical value in the use of groundwater were in good category, namely they conveyed to their children to save water. Parents often rebuke directly if it is seen that children do not use water sparingly. The result of the observation is the houses still provide land for rainwater infiltration and they are all plant a yard with plant and flowers on a pot. There is no houses has biopory and rain fed wells. For this reason, it is recommended that the head of citizen association (RW) give an example and invite community leaders who can explain the importance of instill low value in using water.

Managed aquifer recharge with reverse-osmosis desalinated seawater: modeling the spreading in groundwater using stable water isotopes

Abstract. The spreading of reverse-osmosis desalinated seawater (DSW) in the Israeli coastal aquifer was studied using groundwater modeling and stable water isotopes as tracers. The DSW produced at the Hadera seawater reverse-osmosis (SWRO) desalination plant is recharged into the aquifer through an infiltration pond at the managed aquifer recharge (MAR) site of Menashe, Israel. The distinct difference in isotope composition between DSW (δ18O = 1.41 ‰; δ2H = 11.34 ‰) and the natural groundwater (δ18O = −4.48 ‰ to −5.43 ‰; δ2H = −18.41 ‰ to −22.68 ‰) makes the water isotopes preferable for use as a tracer compared to widely used chemical tracers, such as chloride. Moreover, this distinct difference can be used to simplify the system to a binary mixture of two end-members: desalinated seawater and groundwater. This approach is validated through a sensitivity analysis, and it is especially robust when spatial data of stable water isotopes in the aquifer are scarce. A calibrated groundwater flow and transport model was used to predict the DSW plume distribution in the aquifer after 50 years of MAR with DSW. The results suggest that after 50 years, 94 % of the recharged DSW was recovered by the production wells at the Menashe MAR site. The presented methodology is useful for predicting the distribution of reverse-osmosis desalinated seawater in various downstream groundwater systems.

Inferring groundwater dynamics in a coastal aquifer near wastewater infiltration ponds and shallow wetlands (Kwinana, Western Australia) using combined hydrochemical, isotopic and statistical approaches

A proposal to increase wastewater infiltration at the Kwinana Wastewater Treatment Plant (KWTP) to an unconfined aquifer near a groundwater flow-through wetland (The Spectacles) in Western Australia, prompted a study of the groundwater geochemistry and water levels to identify the water types and to develop a conceptual model for groundwater flow and geochemical evolution. Within the catchment, the water table has dramatically declined (e.g up to −70 to −90 mm/yr over three decades) due to the drying climate and increasing demand for groundwater. Annual rainfall has declined by 9 mm/decade on average or about 1.4% of the annual mean over the last three decadesWastewater infiltration began in 1975 and has increased to the current rate of 4.7 thousand cubic meters per day. Groundwater-surface water interactions were interpreted using multivariate statistical analysis of major ion and stable isotope (δ18O, δD) data. Rainwater infiltrating through the aquifer interacts with carbonate minerals while flowing westward to produce a Ca-HCO3 type of water (Group 1). Below the wetland, groundwater has an evaporative signature (Group 2) that has higher concentrations of TDS (>1 g/L) and distinctively higher δ18O (>2.5 per mil) than groundwater derived from wastewater infiltration (Group 3). The ratio of ions (K:Cl) was used to understand the mixing of water types and to quantify the proportions of wastewater at the site. Water samples collected in 2014 reveal a high proportion (>34%) of wastewater within the uppermost 30 m of aquifer and generally decreasing proportions with distance away from the source. Further investigation of The Spectacles water balance and hydrochemistry is needed to optimally manage and prevent degradation of the water quality. Proposed increases in wastewater recharge may continue to help offset the impact of the drying climate on lake levels.

Infiltration of Sulfate to Enhance Sulfate‐Reducing Biodegradation of Petroleum Hydrocarbons

AbstractThe lack of sufficient electron acceptors, particularly sulfate, can limit the rate of biodegradation of petroleum hydrocarbons (PHCs). Hence, there is a growing interest by remediation practitioners to deliver sulfate to a PHC impacted saturated zone to enhance biodegradation. When shallow contamination is present in a relatively permeable aquifer and site constraints allow, a cost‐effective approach is to apply sulfate on the ground surface. In this investigation a pilot‐scale experiment was conducted to increase our understanding of the delivery of sulfate using a surface‐based method and the resulting impact on a shallow PHC contaminated aquifer. A surficial infiltration pond positioned on the ground surface above a well‐characterized residual PHC source zone was used to control sulfate dosing. A high‐resolution network near the infiltration pond and downgradient of the source zone was employed to monitor relevant geochemical indicators and PHC concentrations. Compound‐specific isotope analysis (CSIA) was used to identify biodegradation patterns and to investigate the occurrence of microbial sulfate reduction. Selected metabolites and reverse‐transcriptase quantitative polymerase chain reaction analyses of expressed biodegradation genes (as mRNA) were also used to characterize the response of indigenous microorganisms (especially sulfate‐reducing bacteria) to the added sulfate. Three sulfate application episodes (5000 L each) at various Na2SO4 concentrations were allowed to infiltrate under a constant hydraulic head. Although the applied sulfate solution was impacted by density‐driven advection, detailed monitoring data indicated that the sulfate‐enriched water mixed with upgradient groundwater as it migrated downward through the residual PHC zone and formed a co‐mingled downgradient plume with the dissolved PHC compounds. The enrichment of δ34S of sulfate in conjunction with a decrease in sulfate concentration showed the occurrence of sulfate reduction due to the applied sulfate. Increased dissolved inorganic carbon (DIC) concentrations associated with a shift toward more depleted values of δ13C of DIC was indicative of an input of isotopically depleted DIC from biodegradation of PHCs. Despite fluctuations in benzene, toluene, and o‐xylene (BTX) concentrations, the CSIA data for BTX showed that these compounds were biodegraded. The biomarker data provided supporting evidence that toluene and o‐xylene were undergoing anaerobic biodegradation due to sulfate reduction. This study provides insight into factors controlling surface‐based delivery of sulfate to shallow PHC impacted groundwater systems, and the value of isotopic and molecular‐biological procedures to augment conventional monitoring tools.

Salt pond analysis using ALOS PALSAR case study Sampang, Madura-Indonesia

Indonesia is a country that has a large sea area of about 96,079.15 km2. With this condition we can utilize the natural resources that are infested in the sea, such as fish, and salt. Indonesia has exceptional salt pond commodities from various areas such as Cirebon, Sampang, Indramayu Madura, and Rembang. These resources need to be monitor and inventory in proper way. The development of science and technology, there is an effective and efficient way to identify, monitoring and inventory of salt ponds using remote sensing technology. In this last period the saltwater pond infiltration is still inclined to utilize optical sensor system to monitor and infuse. The method used is visual interpretation through multipolarization composite radar image by using interpretation key. The weakness of passive sensors is affected by the presence of cloud cover. The location of salt ponds in Indonesia is mostly located on the coastal regions that is visually affected cloud cover. In addition the use of active sensor is become a challenging for this aspect. This study was conducted to analysis of hues, patterns, and textures in order to recognize the salt pond object using Alos PALSAR Image (Active Sensor). The salt pond object in multi-polarized composite HH-HH / HV composite radar images is recognizable in dark blue with regular pattern plots with characterized by brighter / clear / bright pink ridges.

Monitoring induced denitrification during managed aquifer recharge in an infiltration pond

Managed aquifer recharge (MAR) is a well-known technique for improving water quality and increasing groundwater resources. Denitrification (i.e. removal of nitrate) can be enhanced during MAR by coupling an artificial recharge pond with a permeable reactive layer (PRL). In this study, we examined the suitability of a multi-isotope approach for assessing the long-term effectiveness of enhancing denitrification in a PRL containing vegetal compost. Batch laboratory experiments confirmed that the PRL was still able to enhance denitrification two years after its installation in the infiltration pond. At the field scale, changes in redox indicators along a flow path and below the MAR-PRL system were monitored over 21 months during recharge and non-recharge periods. Results showed that the PRL was still releasing non-purgeable dissolved organic carbon five years after its installation. Nitrate concentration coupled with isotopic data collected from the piezometer network at the MAR system indicated that denitrification was occurring in the saturated zone immediately beneath the infiltration pond, where recharged water and native groundwater mix. Furthermore, longer operational periods of the MAR-PRL system increased denitrification extent. Multi-isotope analyses are therefore proved to be useful tools in identifying and quantifying denitrification in MAR-PRL systems.

Assessing the efficiency of a coastal Managed Aquifer Recharge (MAR) system in Cyprus

Managed Aquifer Recharge (MAR) is becoming an attractive water management option, with more than 223 sites operating in European countries. The quality of the produced water, available for drinking or irrigation processes is strongly depended on the aquifer's hydrogeochemical characteristics and on the MAR system design and operation. The objective of this project is the assessment of the operation efficiency of a MAR system in Cyprus. The coupling of alternative methodologies is used such as water quality monitoring, micro-scale sediment sorption experiments, simulation of groundwater flow and phosphate and copper transport in the subsurface using the FEFLOW model and evaluation of the observed change in the chemical composition of water due to mixing using the geochemical model PHREEQC. The above methodology is tested in the Ezousa MAR project in Cyprus, where treated effluent from the Paphos Waste Water Treatment Plant, is recharged into the aquifer through five sets of artificial ponds along the riverbed. Additionally, groundwater is pumped for irrigation purposes from wells located nearby. A slight attenuation of nutrients is observed, whereas copper in groundwater is overcoming the EPA standards. The FEFLOW simulations reveal no effective mixing in some intermediate infiltration ponds, which is validated by the inverse modeling simulation of the PHREEQC model. Based on the results, better control of the infiltration capacity of some of the ponds and increased travel times are some suggestions that could improve the efficiency of the system.

Geochemical Processes During Managed Aquifer Recharge With Desalinated Seawater

AbstractWe study geochemical processes along the variably‐saturated zone during managed aquifer recharge (MAR) with reverse‐osmosis desalinated seawater (DSW). The DSW, post‐treated at the desalination plant by calcite dissolution (remineralization) to meet the Israeli water quality standards, is recharged into the Israeli Coastal Aquifer through an infiltration pond. Water quality monitoring during two MAR events using suction cups and wells inside the pond indicates that cation exchange is the dominant subsurface reaction, driven by the high Ca2+ concentration in the post‐treated DSW. Stable isotope analysis shows that the shallow groundwater composition is similar to the recharged DSW, except for enrichment of Mg2+, Na+, Ca2+, and . A calibrated variably‐saturated reactive transport model is used to predict the geochemical evolution during 50 years of MAR for two water quality scenarios: (i) post‐treated DSW (current practice) and (ii) soft DSW (lacking the remineralization post‐treatment process). The latter scenario was aimed to test soil‐aquifer‐treatment (SAT) as an alternative post‐treatment technique. Both scenarios provide an enrichment of ∼2.5 mg L−1 in Mg2+ due to cation exchange, compared to practically zero Mg2+ currently found in the Israeli DSW. Simulations of the alternative SAT scenario provide Ca2+ and remineralization due to calcite dissolution at levels that meet the Israeli standard for DSW. The simulated calcite content reduction in the sediments below the infiltration pond after 50 years of MAR was low (<1%). Our findings suggest that remineralization using SAT for DSW is a potentially sustainable practice at MAR sites overlying calcareous sandy aquifers.

Experiment in infiltration studies as a water treatment process

This article contains the concept of research methodology of the water infiltration process. The described research was conducted at Dębina intake in Poznan, Poland. Based on the temperature variation curves, it was possible to determine the water retention time in the ground during the flow of water from the infiltration pond through piezometers to the collecting well

Identifying Possible Locations to Construct Soil Water Conservation Structures by Using Hydrogeological and Geospatial Analysis

Abstract Identification of soil water conservation structures (SWCs) necessitates as the proximity of study area (Shivganga watershed) to the Western Ghats imparts high rainfall and runoff, resulting to accelerate soil erosion. To decrease soil erosion and improve water storage as well as recharge, the investigation of new possible structures is necessary. With this intent, suitable sites for SWC structures (check dam and percolation ponds) were identified by using hydro-spatial data such as soil, land use/cover, slope, runoff, infiltration data from IRS P6 LISS-IV imagery and other collateral data. Further, acquired data were processed to derive runoff by employing Soil Conservation Service Curve Number (SCS-CN) method and infiltration by Allen (2008) method. The Integrated Mission for Sustainable Development (IMSD) specifications were used for the identification of locations for constructing SWC structures. The results revealed that about 28% area is suitable for implementation of SWC structures. Total 45 locations SWC structures were derived with the present method, out of that 20 were already built. The superimposition of derived and existing locations shows (80-100%) accuracy, authenticates the reliability of the method. The present modified method will definitely help in speedy identification of a location for SWC structures.

Water quality of stormwater generated from an airport in a cold climate, function of an infiltration pond, and sampling strategy with limited resources.

Monitoring pollutants in stormwater discharge in cold climates is challenging. An environmental survey was performed by sampling the stormwater from Luleå Airport, Northern Sweden, during the period 2010-2013, when urea was used as a main component of aircraft deicing/anti-icing fluids (ADAFs). The stormwater collected from the runway was led through an oil trap to an infiltration pond to store excess water during precipitation periods and enhance infiltration and water treatment. Due to insufficient capacity, an emergency spillway was established and equipped with a flow meter and an automatic sampler. This study proposes a program for effective monitoring of pollutant discharge with a minimum number of sampling occasions when use of automatic samplers is not possible. The results showed that 90% of nitrogen discharge occurs during late autumn before the water pipes freeze and during snow melting, regardless of the precipitation during the remaining months when the pollutant discharge was negligible. The concentrations of other constituents in the discharge were generally low compared to guideline values. The best data quality was obtained using flow controlled sampling. Intensive time-controlled sampling during late autumn (few weeks) and snow melting (2 weeks) would be sufficient for necessary information. The flow meters installed at the rectangular notch appeared to be difficult to calibrate and gave contradictory results. Overall, the spillway was dry, as water infiltrated into the pond, and stagnant water close to the edge might be registered as flow. Water level monitoring revealed that the infiltration capacity gradually decreased with time.

Concentrating solar power plants versus groundwater resources in Mediterranean areas of Spain: The environmental dilemma

Concentrating solar power plants (CSPPs) are considered to be particularly respectful of the environment but under Mediterranean climate where surface water scarcity is a key issue, these types of electrical plants usually require groundwater for their cooling towers and use the same aquifers to discharge their salinized effluents. This study analyses de Spanish case, where fifteen out of the fifty active CSPPs use groundwater directly, four discharge their effluents to infiltration ponds and forty-three to surface watercourses most of which recharge underlying aquifers. The volume of water withdrawn and discharged varies greatly among similar plants. The salinity of the effluent exceeds 2.5 times that of the withdrawn water in half of the plants and it may alter the current or potential use of the water turning it unsuitable for drinking or even for irrigation. There is a risk that the impact on groundwater can be extended to related ecosystems such as wetlands. This can become a serious environmental problem, but specific impacts on groundwater are often overlooked in environmental impact assessments of CSPPs and no research on the matter has been reported so far. Other legal and political implications of CSPPs are further discussed.