Amudarya River Basin

Water resources of Amudarya River Basin

The total mean annual flow of all rivers in the Amudarya river basin (without the Zeravshan) estimated about 74.22 km3. In accordance with flow probabilities at 5% (high wet years) and 95% (dry years), the annual flow ranges from 102 to 55.1 km3.

Natural surface flow in the Amudarya River basin (mean annual runoff, km3/year)

River basin

River flow generated within the countries

Total Amudarya Basin

Kyrgyzstan

Tajikistan

Uzbekistan

Turkmenistan

Afghanistan and Iran

Pyandj

30.081

3.300

33.381

Vakhsh

1.654

18.400

20.054

Kafirnigan

5.575

5.535

Surkhandarya

4.841

4.841

Sherabad

0.228

0.228

Kashkadarya

1.222

1.222

Murgab

0.771

0.771

1.542

Tedjen

0.488

0.489

0.977

Atrek

0.136

0.137

0.273

Rivers of Afghanistan

6.167

6.167

Total (km3)

1.654

54.056

6.291

1.405

10.814

74.22

Amudarya Basin (%)

2.2

72.8

8.5

1.9

14.6

100



Estimated regional reserves of groundwater in the Amudarya basin are about 14.7 km3. Because exploitation of groundwater can have an impact on surface water flows, the quantification of groundwater resources must, therefore, be careful to identify that portion of the reserves that could be used without significantly diminishing surface runoff. The reserves confirmed for extraction are estimated at 7.1 km3 per year. Total actual (1998) groundwater extraction in the Amudarya river basin was about 4.8 km3.

There are presented figures about return flow in the Amudarya river basin in the Table below. Return water is the main source of environmental pollution in the Amudarya river basin. Sulphates, chlorides and sodium ions prevail in drainage water, which also contains pesticides, nitrogen and phosphate compounds. Up to 25 percent of the nitrogen, 5 percent of phosphate and up to 4 percent of pesticides introduced into the soil are carried into drainage collectors from fields. The concentration of these pollutants in drainage water exceeds the maximum permissible concentration by 5 to 10 times. Mineralization and the content of principal ions are also high, increasing from mountainous regions downwards. Calculation of the amount of salt carried by drainage water has shown that the Amudarya section between the Nurek reservoir and its confluence with the Vakhsh river receives about 8.5 million tons of salt annually, and the Pyanj River, up to 0.8 million tons. Between the confluence of the Vakhsh and the Pyanj rivers and the Tuyamuyun reservoir, up to 16.5 million tons are dumped into the Amudarya.

Below Tuyamuyn, another 1.6 million tons of salt are dumped into the Amudarya. Water mineralization data in the two main cross-sections of the Amudarya show that irrigation resulted in greater than permissible mineralization in the Tuyamuyun bed reaching up to 1.76 g/l already in the beginning of 1980s.

The dynamics of changes affecting the middle reaches of the Amudarya River

Factors

Unit

1965-1970

1971-1975

1976-1980

1981-1985

1986-1990

Irrigation area

th. ha

386.1

641.7

984.1

1238

1352.3

River flow at Kerki

km3

61.3

55.5

60.5

56.2

46.7

Mineralization at Kerki

g/l

0.43

0.53

0.64

0.60

0.60

Salt runoff at Kerki

mln. t

26.4

28.9

36.9

33.7

27.6

Water consumption

km3

16.6

18.1

22,2

23.5

28.3

Drainage outflow to river

km3

1.26

1.69

2.59

3.55

2.57

Mineralization of drainage runoff

g/l

3.02

3.2

3.50

3.84

3.97

Salt disposal

mln. t

3.8

5.4

9.3

13.6

10.2

River flow at Tuyamuyun

km3

44.7

37.4

38.3

32.7

18.4

Mineralization at Tuyamuyun

g/l

0.44

0.58

0.78

0.95

1.06