Loading...
7 results
Search Results
Now showing 1 - 7 of 7
- Assessing the use of harvested greenhouse runoff for managed aquifer recharge to improve groundwater status in South PortugalPublication . Costa, Luis; P. Monteiro, J.; Hugman, Rui TwohigConcentration of nitrates in groundwater at the Nitrate Vulnerable zone of Faro, south Portugal, reaches values as high as 300 mg/l; therefore, according to the EU Water Framework Directive, mitigation measures need to be implemented. A Managed Aquifer Recharge scheme is proposed to accelerate the dilution and natural discharge of nitrates from the system. Source water availability is estimated from rainfall intercepted at existing greenhouses. Within the highest nitrate concentration area, estimated water availability for injection in existing wells is 1.50 hm(3)/year, a significant volume which represents approximately 15% of the aquifer direct recharge. It is proposed this is recharged to the aquifer through existing large-diameter traditional wells that are no longer used for abstraction. Injection test results suggest that the likely infiltration capacity of such wells is more than sufficient to allow collection of 95% of daily rainfall events. The effect of injecting this volume in the aquifer was estimated with the support of a 3D numerical groundwater flow and transport model. Results show considerable improvement in nitrate concentrations in the study area, in certain locations decreasing up to 70 mg/l by 2027. The model results predict a decrease in the number of nitrate threshold exceedances in observation points, from 33 to 30 by 2027 and 14 to 9 by 2040. It is likely that this measure may have a positive effect on other issues identified in the area, mostly related with quantity problems and seawater intrusion. Notwithstanding, issues including landowner support, clogging, conditions of greenhouses and wells, water quality, and climate change impacts will require further consideration to develop a successful and beneficial MAR scheme.
- In-channel managed aquifer recharge: a review of current development worldwide and future potential in EuropePublication . Standen, Kathleen; Costa, Luis; Monteiro, José PauloManaged aquifer recharge (MAR) schemes often employ in-channel modifications to capture flow from ephemeral streams, and increase recharge to the underlying aquifer. This review collates data from 79 recharge dams across the world and presents a reanalysis of their properties and success factors, with the intent of assessing the potential of applying these techniques in Europe. This review also presents a narrative review of sand storage dams, and other in-channel modifications, such as natural flood management measures, which contribute to the retardation of the flow of flood water and enhance recharge. The review concludes that in-channelMARsolutions can increase water availability and improve groundwater quality to solve problems a ecting aquifers in hydraulic connection with temporary streams in Europe, based on experiences in other parts of the world. Therefore, to meet the requirements of the Water Framework Directive (WFD), in-channel MAR can be considered as a measure to mitigate groundwater problems including saline intrusion, remediating groundwater deficits, or solving aquifer water quality issues.
- Integration of managed aquifer recharge into the water supply system in the Algarve region, PortugalPublication . Standen, Kathleen; Costa, Luís; Hugman, Rui; Monteiro, José PauloThe Algarve region of Portugal is experiencing severe water scarcity with existing water supplies insufficient to meet demand, with limited resilience to drought. Managed aquifer recharge (MAR) can provide intermediate storage and bridge the gap between water availability and demand, with success depending on the water available and the aquifer capacity to accept and store the water. We present the results of a regional study quantifying both these aspects to estimate the regional potential for MAR. Our results demonstrate that MAR can comprise 10% of the total water demand of the region (24 Mm3/yr) using water that is not otherwise captured, with quality that meets the requirements of the Groundwater Directive. MAR can replace 15 Mm3/yr of surface water used in the public irrigation perimeters and 9 Mm3/yr can be used to develop and maintain a strategic groundwater resource in the aquifers of the Central Algarve. Although climate change is predicted to result in an 8–13% decrease in MAR recharge, this can be addressed by incrementally increasing MAR design capacity. MAR has similar water resource benefits to the planned major infrastructure projects (desalination and River Guadiana abstraction), with reduced environmental impacts and lower costs than almost all feasible alternatives. We conclude that MAR is an important measure to increase water supply security and drought resilience in the Algarve region.
- Predicting the impact of management and climate scenarios on groundwater nitrate concentration trends in southern PortugalPublication . Costa, Luis; Hugman, Rui; Stigter, Tibor Y.; Monteiro, José PauloThe dynamics related to evolution of nitrate-contaminated groundwater are analyzed with focus on the impact of intrinsic aquifer properties, agricultural activities and restoration measures at Campina de Faro aquifer (M12), southern Portugal. Agricultural practices in the region developed in the 1970s and resulted in high abstraction rates, nitrate contamination and salinization. Despite the implementation of the European Union (EU) Nitrates Directive since 1997, nitrate levels still show increasing trends at some locations, constituting a threat to the chemical status of M12 and consequent nitrate discharge to Ria Formosa coastal lagoon. Simultaneously, groundwater levels are not dropping consistently, despite apparent overexploitation. A groundwater flow and mass transport model is developed for M12 to assess the evolution of nitrate under different scenarios. Model results reveal that M12 has a hydraulic connection with northernmost aquifers, a process not properly assessed so far. Results further show that nitrate contamination in the upper Plio-Quaternary layer of M12 is extremely persistent and mostly linked to unbalanced fertilizer application practices and irrigation return flows. The response of M12 to implementation of good agricultural practices in compliance with EU policies is slow, indicating that good qualitative status would be impossible to reach by the required EU deadlines. Integration of climate change scenarios into the transport model reveals that despite the implementation of restoration measures, there could be a retardation of the nitrate levels' decrease in the upper aquifer as a result of enhanced evapoconcentration caused by lower recharge, higher water demands and incomplete mixing within the aquifer.
- Decision-support groundwater modelling of managed aquifer recharge in a Coastal Aquifer in South PortugalPublication . Standen, Kathleen; Hugman, Rui; Monteiro, José PauloThe Vale do Lobo sector of the Campina de Faro aquifer system in the Algarve (Portugal) is at risk of seawater intrusion. Managed Aquifer Recharge (MAR) is being considered to avoid groundwater quality deterioration. Numerical modelling was undertaken to assess the feasibility of several proposed MAR schemes. Although some data is available, many aspects of system behaviour are not well understood or measured. We demonstrate the use of a structurally simple but parametrically complex model for decision-making in a coastal aquifer. Modelling was designed to facilitate uncertainty reduction through data assimilation where possible, whilst acknowledging that which remains unknown elsewhere. Open-source software was employed throughout, and the workflow was scripted (reproducible). The model was designed to be fast-running (rapid) and numerically stable to facilitate data assimilation and represent prediction-pertinent uncertainty (robust). Omitting physical processes and structural detail constrains the type of predictions that can be made. This was addressed by assessing the effectiveness of MAR at maintaining the fresh-seawater interface (approximated using the Ghyben-Herzberg relationship) below specified thresholds. This enabled the use of a constant-density model, rather than attempting to explicitly simulating the interaction between fresh and seawater. Although predictive uncertainty may be increased, it is outweighed by the ability to extract information from the available data. Results show that, due to the limit on water availability and the continued groundwater extraction at unsustainable rates, only limited improvements in hydraulic heads can be achieved with the proposed MAR schemes. This is an important finding for decision-makers, as it indicates that a considerable reduction in extraction in addition to MAR will be required. Our approach identified these limitations, avoiding the need for further data collection, and demonstrating the value of purposeful model design.
- Integration of managed aquifer recharge into the water supply system in the Algarve region, PortugalPublication . Standen, Kathleen; Costa, Luís; Hugman, Rui; Monteiro, José PauloThe Algarve region of Portugal is experiencing severe water scarcity with existing water supplies insufficient to meet demand, with limited resilience to drought. Managed aquifer recharge (MAR) can provide intermediate storage and bridge the gap between water availability and demand, with success depending on the water available and the aquifer capacity to accept and store the water. We present the results of a regional study quantifying both these aspects to estimate the regional potential for MAR. Our results demonstrate that MAR can comprise 10% of the total water demand of the region (24 Mm(3)/yr) using water that is not otherwise captured, with quality that meets the requirements of the Groundwater Directive. MAR can replace 15 Mm(3)/yr of surface water used in the public irrigation perimeters and 9 Mm(3)/yr can be used to develop and maintain a strategic groundwater resource in the aquifers of the Central Algarve. Although climate change is predicted to result in an 8-13% decrease in MAR recharge, this can be addressed by incrementally increasing MAR design capacity. MAR has similar water resource benefits to the planned major infrastructure projects (desalination and River Guadiana abstraction), with reduced environmental impacts and lower costs than almost all feasible alternatives. We conclude that MAR is an important measure to increase water supply security and drought resilience in the Algarve region.
- Evaluation of GRACE data for water resource management in Iberia: a case study of groundwater storage monitoring in the Algarve regionPublication . Neves, Maria C.; Nunes, Luís; Monteiro, José PauloStudy region: Iberia, Algarve basin, South Portugal. Study focus: This study evaluates the performance of several GRACE products in Iberia using the closure of the water budget. Then, it focusses on the Algarve region and explores the potential of GRACE as a tool of quantitative groundwater monitoring capable of bridging gaps in the existing ground-based network. Monthly data from GRACE, ancillary datasets from E-OBS, GLEAM, GRUN and ERA5, and groundwater level measurements from 12 karst-porous aquifers in the Algarve basin (5000 km2) are analyzed from 2004 to 2014. New Hydrological Insights for the Region: When considering the closure of the water budget at the Iberian scale, GRACE Mascon solutions perform remarkably well and better than the products based on spherical harmonics. When considering only the Algarve region, the results are similar to the ones obtained for Iberia, but the GRACE solution that performs the best is the average of the CSR and JPL Mascon products. In spite of the Algarve’s extremely small area when compared to the GRACE footprint, the satellite is capable of capturing the regionally averaged seasonal and deseasonalized variations in observed groundwater storage (correlation between GRACE-derived and regionally averaged ground-based measurements is 0.82). For the first time ever at the regional Algarve scale, bounds are placed on the aquifer’s storage properties which vary from 3.65 × 10 3 to 4.92 × 10 2.