the interrelation between water inflow and discharge for any part of the land surface during a given time, taking human economic activity into consideration.
A water-conservation balance is drawn up for the basins of inland seas (for example, the Caspian) or for rivers or their parts, both for years of varying water levels and for the most critical months during years when there is a water shortage. The inflow portion of the balance is composed of the dis-charge of surface and underground waters formed by precipitation from the atmosphere, recycled water from sewer systems, water that filters through from irrigated fields, and water that has come from other basins. The discharge portion comprises evaporation from the surface, water collected for production needs (for example, irrigation or industrial water supply) and for household water supply, and water that flows out to other basins. The water-conservation balance gives an idea of the water supply of a given basin and, when there is a negative balance, of the necessity for measures to make up the water shortage. The basin of the Caspian Sea is an example of a negative water-conservation balance: from 1929 through 1945 its inflow was 49 cu km less than the long-term average, which resulted in a sharp (2.5 m) lowering of the level of the Caspian Sea in comparison with the level ob-served over the past 100 years.
G. G. GANGARDT