|
BOX 7 Aquifer An underground stratum that is saturated with water and transmits water readily. Command and control A system of water supply or quality management based on administrative allocations (in contrast to incentive or price-based allocations). Cost recovery Fee structures to cover the cost of providing a service. Demand management The use of economic, legal, institutional and other policy interventions to influence the demand for water. Drip irrigation Localized drop-by-drop application of water that uses pipes, tubes, filters, emitters and ancillary devices to deliver water to specific sites at a point or grid on the soil surface. Ecosystem A complex system formed by the interaction of a community of organisms with its environment. Externality The uncompensated, unintended side-effects of one party's actions on another party. Gravity irrigation A system that depends on sloping canals and fields for the transportation of water to the irrigated site. Groundwater table The level of water storage (above mean sea level) in an aquifer; hence, the point at which the soil is fully saturated with water. Irrigated area i) Gross irrigated area. The area of land irrigated in a year (land having two irrigation seasons is counted twice). ii) Net irrigated area. The area of land surface that receives irrigation water in a year (two irrigation seasons are counted as one). Irrigation Human intervention to modify the distribution of water in natural channels, depressions, drainageways or aquifers and to manipulate this water for improving the production of agricultural crops or enhancing the growth of other desirable plants. Riparian state A state through or along which a portion of a river flows or in which a lake lies. River basin A geographical area determined by the watershed limits of a system of waters, including surface and underground waters, flowing into a common terminus. Seepage The infiltration of water downwards or laterally into soil or substrata from a source of supply such as a reservoir, irrigation canal or channel. Sewage Liquid refuse or waste matter carried off by surface water via sewers. Sewerage The removal and disposal of sewage and surface water by sewer systems. Sustainable development The management and conservation of the natural resource base and the orientation of technological and institutional change in such a manner as to ensure the attainment and continued satisfaction of human needs for the present and future generations. Such sustainable development (in the agricultural, forestry and fisheries sectors) conserves land, water, plant and animal genetic resources and is environmentally non-degrading, technically appropriate, economically viable and socially acceptable. Tube wells Wells consisting of perforated tubes or pipes placed in holes bored into the ground to tap groundwater supplies from one or more aquifers. Underflow The underground flow or movement of water in an aquifer. Underground transmission Water distribution by means of underflows within an aquifer system. Water quality This is defined by the level of dissolved salts and/or other contaminants. Acceptability may vary with the intended use, i.e. drinking-water requires higher-quality water than irrigation. Waterlogging and salinization Unproductive soil conditions that occur when the water table is very near the surface. Waterlogging is caused by overwatering and a lack of proper drainage. Salinity is caused by a combination of poor drainage and high evaporation rates that concentrate salts on irrigated land. Watershed An area drained by a river or stream system. Watershed management A process of formulating and implementing a course of action that involves natural and human resources, taking into account social, political, economic, environmental and institutional factors that operate within the watershed, the surrounding river basin and other relevant regions, to achieve desired social objectives. Wetlands Areas of marsh, fen, peat land or water that include natural,
artificial, permanent or temporary areas with either static or flowing fresh,
brackish or marine water. |
