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Amudarya River Basin

Water losses along the Amudarya River

Water flow varies along the course of the river. Its variations depends on groundwater influx into the river in the zone of flow formation, return waters inflow into the transit area which varies according to water level, and flow losses in the lowest delta area. Some loss also occurs due to evaporation and filtration in reservoirs. At present, summary loss from reservoirs due to evaporation and filtration amounts to about 1.4 km3/year in the Amudarya basin.

A considerable amount of water is lost in riverbeds. Observation is the most reliable measurements available to assess the losses; water balance calculations are only approximate assessments. Previous observations gave the following average figures on water losses from the riverbed:

- River reach from confluence of the Payndj and Vaksh rivers up to Kerki 1.2 km3/year;

- KerkiTuyamuyun 3.6 km3/year;

- Downstream from Tuyamuyun 1.4 km3/year.

At present, the most difficult is assessing riverbed losses in the Amu River downstream from the town of Kerki. Last five years observations in this part of river have shown that the losses vary considerably, from 7.0 up to 13.0 km3/year. This amount comparable with 20...40% of total water intakes value to the canals. Tables 2 and 3 represent the analyses of water balances for two river reaches between Kerki and Tuyamuyun in 1996 (one of the problematic years). From these Tables it is seen, that even taking into account the losses for evaporation, filtration and riverbed storage, there is a huge imbalance. The reason for these high imbalances is unexplainable, as general climatic and hydrologic factors do not support them. A more thorough study of this problem is necessary in the nearest future. In addition to recording observational data, a number of control measurements of riverbed losses should be made. Actual water losses due to evaporation in former river beds, floodplains and natural depressions should be assessed with the help of remote sensing methods. From these measurements, proposals may be made to reduce unproductive flow losses in the Amudarya river basin exceeding 3.5-5.0 km3/year.

Another related to this problem, mainly from operational point of view, is long distance between gauging stations, where river flow is measured. For example, water flows from Nurek water reservoir to Tuyamuyan reservoir during about 14-16 days. It creates also a certain problems in accounting of flow transformation along the river and decision making in water resources management.