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The last 60 years has seen unprecedented groundwater extraction and overdraft as well as development of new technologies for water treatment that together drive the advance in intentional groundwater replenishment known as managed aquifer recharge (MAR). This paper is the first known attempt to quantify the volume of MAR at global scale, and to illustrate the advancement of all the major types of MAR and relate these to research and regulatory advancements. Faced with changing climate and rising intensity of climate extremes, MAR is an increasingly important water management strategy, alongside demand management, to maintain, enhance and secure stressed groundwater systems and to protect and improve water quality. During this time, scientific research—on hydraulic design of facilities, tracer studies, managing clogging, recovery efficiency and water quality changes in aquifers—has underpinned practical improvements in MAR and has had broader benefits in hydrogeology. Recharge wells have greatly accelerated recharge, particularly in urban areas and for mine water management. In recent years, research into governance, operating practices, reliability, economics, risk assessment and public acceptance of MAR has been undertaken. Since the 1960s, implementation of MAR has accelerated at a rate of 5%/year, but is not keeping pace with increasing groundwater extraction. Currently, MAR has reached an estimated 10 km3/year, ~2.4% of groundwater extraction in countries reporting MAR (or ~1.0% of global groundwater extraction). MAR is likely to exceed 10% of global extraction, based on experience where MAR is more advanced, to sustain quantity, reliability and quality of water supplies.

Chemical fertilizer use in Egypt has increased significantly since the construction of the Aswan High Dam in 1968. Increased applications of chemical fertilizers in irrigated lands are likely to create nonpoint contamination sources of chemical fertilizer species. This study was conducted to investigate the contamination of ground water by nitrogen and phosphorus chemical fertilizers, as well as the availability of ground water for irrigation and public water supply for the next century. Future concentrations of NO3, and PO3‐ in shallow and deep ground water in the Nile Valley were assessed under realizable rates of fertilizer application. A ground water modeling system (GMS) was used to simulate the three‐dimensional ground water flow and contaminant transport in the Tahta region of the Nile Valley Aquifer, and to predict the future concentrations of chemical fertilizer species. Results of the transport simulation predict the occurrence of ground water contamination at shallow depths (30 m) due to the high rate and method of chemical fertilizer applications. Best management practices should be employed to control and reduce the nitrate leaching and future impact of phosphorus and potassium fertilizer applications. At the same time, new deeper wells should be constructed. In addition, the use of hand pumps, in zones close to croplands (15 m depth) must be avoided due to susceptibility to fertilizer contamination. Ground water from existing deep wells can be used as an alternative water supply. Furthermore, a ground water quality monitoring system should be established for early detection of ground water contamination and to determine progress of the fertilizer contaminant plume. A properly designed system should monitor nitrate and phosphate composition in observation and water supply wells.