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            Dam Structure built to hold back a flow of water 
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            Delta Fan-shaped area at the mouth of a river formed by deposition of sediments 
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            Demand management Measures taken to predict and meet consumer demand for environmentally sensitive goods such as water, e.g. through activities that alter water use 
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            Depletion The loss of water from surface water reservoirs or groundwater aquifers due to usage at a greater rate than they are recharged 
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            Deposition The gradual dropping or laying down of matter by a natural process, or getting rid of sediments as performed by an agent of erosion, such as a river or glacier; also called sedimentation 
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            Desalination The process of removing salt from seawater or brackish water 
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            Desertification Land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities 
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            Developed water Water that is produced or brought into a water system through the efforts of people (where it would not have entered the water system on its own accord) 
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            Disbursement The action of paying out money 
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            Discharge The amount of water flowing past a location in a river or stream in a certain amount of time; usually expressed in volumes (liters per second or gallons per minute) 
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            Drainage basin All the land that serves as the drainage area of a specific stream or river; See Basin 
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            Drip irrigation Common method of irrigation, in which water trickles slowly through pipes or tubes onto crops. Drip irrigation is a low-pressure method of irrigation with the advantage that less water is lost to evaporation than with high-pressure spray  
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            Drought The naturally occurring phenomenon that exists when precipitation has been significantly below normal recorded levels, causing serious hydrological imbalances that adversely affect land resource production systems