Author
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Bouwer, Herman |
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Submitted to: Hydrogeology Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/1/2002 Publication Date: N/A Citation: N/A Interpretive Summary: Artificial recharge of groundwater can be expected to increase worldwide as populations rise, demands for water increase, water resources are finite, dams for surface storage are increasingly difficult to build. Also, dams can have significant evaporation losses. Seasonal or long-term underground storage (water banking), where possible, is often preferred. Artificial recharge also plays an important role in water reuse because it gives wate quality improvement (soil-aquifer treatment) and storage opportunities to absorb differences between supply and demand for reclaimed sewage effluent. Where sewage effluent is to be used for potable purposes, recharge and recovery breaks the toilet-to-tap connection of water reuse and enables blending with natural groundwater. Combined with soil-aquifer treatment, these aspects enhance the aesthetics and public acceptance of potable water reuse. Water reuse and storage of surplus water for use in times of water shortage also must be increasingly relied upon to cope with uncertainties in future climates and their effect on surface and groundwater supplies. Design and management of artificial recharge systems involves geological, geochemical, hydrological, and engineering aspects. Since soils and underground formations are inherently heterogeneous, planning, design and construction of groundwater recharge schemes must be piecemeal, first testing for fatal flaws and general feasibility, and then proceeding with pilot and small scale systems until the complete system can be designed and constructed. Beneficiaries are water resources planners and managers, consultants, municipalities, government agencies, environmentalists, and the public at large. Technical Abstract: Artificial recharge of groundwater is achieved by putting surface water in basins, furrows, ditches, or other facilities where it can infiltrate into the soil and move downward to recharge aquifers. Artificial recharge is increasingly used for short or long-term storage where it has several advantages over surface storage, and in water reuse. Artificial recharge requires permeable surface soils. Where these are not available, trenches shafts in the unsaturated zone can be used, or water can be directly inject into aquifers through wells. To design a system for artificial recharge of groundwater, infiltration rates of the soil must be determined and the unsaturated zone between land surface and the aquifer must be checked for adequate permeability and absence of polluted areas. The aquifer should be sufficiently transmissive to avoid excessive buildup of groundwater mounds. This requires field investigations and, if no fatal flaws are detected, tes sbasins to predict system performance. Water quality issues must be evaluat especially with respect to formation of clogging layers on basin bottoms or other infiltration surfaces, and to geochemical reactions in the aquifer. Clogging layers are managed by desilting or other pretreatment of the water and by remedial techniques such as drying, scraping, disking, ripping, or other tillage. Recharge wells should be pumped periodically to backwash clogging layers. |
