Переведите текст , без переводчиков. the scope remains global and macroscopic, though there may be regional differences depending on the water sources available in a particular setting. structures such as dams may be used to impound water for consumption. there are various challenges that large-scale dam projects may present to sustainability: negative environmental impacts on wildlife habitats, fish migration, water flow and quality, and socioeconomic impacts resulting from resettled local communities. a sustainability impact assessment should therefore be performed to determine the environmental, economic and social consequences of the construction. groundwater accounts for greater than 50% of global freshwater; thus, it is critical for potable water (lozan et al, 2007). groundwater can be a sustainable water supply source if the total amount of water entering, leaving, and being stored in the system is conserved. there are three main factors which determine the source and amount of water flowing through a groundwater system: precipitation, location of streams and other surface-water bodies, and evapotranspiration rate; it is thus not possible to generalize a sustainable withdrawal or pumping rate for groundwater (usgs, 1999). unsustainable groundwater use results in water-level decline, reduced streamflow, and low water quality, jeopardizing the livelihood of effected communities. various practices of sustainable groundwater supply include changing rates or spatial patterns of ground-water pumpage, increasing recharge to the ground-water system, decreasing discharge from the groundwater system, and changing the volume of groundwater in storage at different time scales (usgs, 1999). a long-term vision is necessary when extracting groundwater since the effects of its development can take years before becoming apparent. it is important to integrate groundwater supply within adequate land planning and sustainable urban drainage systems.