Introduction

The Syr Darya Basin (Fig. 5.1) is one of two major basins in the Aral Sea Basin in Central Asia. It has an area of 402,760 km2 divided between the four ex-Soviet states of Kyrgyzstan, Uzbekistan, Tajikistan and Kazakhstan. Approximately 20 million people inhabit the basin, 73% living in rural areas, making their living from agriculture. About 55% of the land is used as pastures supporting livestock of sheep, cattle, goats, horses and camels. Furthermore, 8% of the land is used for crop production. The climate in the basin is hot and arid, but in the mountains the climate is more cool and humid. Soils are thin and infertile, but can be productive for certain crops with adequate irrigation, which is not abundant in the region. An immense irrigation network inherited from Soviet times is still in operation, but in part needs renovation and reconstruction in order to increase irrigation efficiency and hence better use of valuable water resources.

After the disintegration of the USSR, the strictly centralized water management system came to an end, and the problems with coordination of water management became a hot issue in the region. There is a distinct conflict of interests between the industrial and agricultural users of water across the different transboundary countries. The major hydropower plants are in the upper stream Kyrgyz Republic, while main irrigated crop land is in the other three countries, thus downstream agriculture is in a more vulnerable position. The largest reservoir in the basin, the Toktogul artificial lake (located in the territory of the Kyrgyz Republic), has the key position because of its location in the upper part of the basin and its capacity to hold more than half of all artificial water storage in the basin. The lake supports a hydropower plant. Before the disintegration of the Soviet Union in 1990, Toktogul lake outflow and hydropower production were regulated taking into consideration the demands for water for irrigation downstream. After

© CAB International 2004. Climate Change in Contrasting River Basins

Fig. 5.1. The Syr Darya Basin in Central Asia.

1990, Kyrgyzstan started acting in its own interests, generating more hydropower for domestic needs in the cold period of the year, when the demands are higher, thus drastically reducing water supply to the agricultural areas of Kazakhstan and Uzbekistan in summer (Fig. 2.9). An attempt to settle the crisis was made when Kazakhstan and Uzbekistan both signed bilateral swap agreements with Kyrgyzstan to exchange coal and electricity for water. Though these states failed a number of times to meet the agreed targets, nevertheless, the existing institutions for the regulation of the transboundary water allocation may be considered quite effective in solving the problem.

The main environmental issue in the Syr Darya Basin remains the collapse of natural ecosystems in the area of the Syr Darya Delta. Here, once productive wetlands have turned into a drying bed of the northern Aral Sea since the 1960s. As a consequence, the fish population of the lake has drastically reduced, virtually eliminating the commercial fishing industry in the region. Furthermore, the exposure of the dried-up bed of the Aral Sea allowed strong winds to erode the underlying sediments, con-

□ Average discharge R. Naryn, Uchkurgan (1960-1987) ■ Average discharge R. Naryn, Uchkurgan (1988-2000)

□ Average discharge R. Naryn, Uchkurgan (1960-1987) ■ Average discharge R. Naryn, Uchkurgan (1988-2000)

Fig. 5.2. Average monthly Toktogul lake outflow in 1960-1987 (grey columns) and 1988-2000 (black columns).

tributing to a deterioration of air quality for the nearby residents and soil quality due to salt-laden particles falling on arable land. Salinization and waterlogging due to irrigation represent serious threats to irrigated land. The area affected has increased during the last decade from roughly 25% to 50% of irrigated land (Raskin et al., 1992; Heaven et al., 2002). According to Rust et al. (2001), presently 31% of the irrigated area has a water table within 2 m of the surface and 28% of the irrigated area suffers from moderate to high salinity levels, which result in a crop yield decline of 20-30%.

The water development system of the region is called 'one of the most complicated water development systems in the world' (Raskin et al., 1992, p. 57). Six large artificial water reservoirs and a number of smaller ones constructed for the purposes of water storage for irrigation and hydropower production have in sum a water storage capacity of 35 km3. Agricultural water demands by far outweigh those of industry and domestic needs. In the last four decades, the water resources were heavily overexploited, which resulted in a dramatic decrease in the outflow of the Syr Darya to the Aral Sea (see Table 5.1). That, together with overexploitation of water resources in the Amu Darya Basin, led to a dramatic drop in the level of the Aral Sea and an environmental catastrophe in the delta areas of both rivers.

The last decade's changes in the running of the water reservoirs caused not only downstream water shortages over summer, but also an excess of water in winter that

Table 5.1. Syr Darya outflow to Aral Sea.

Period

Runoff (km3)

Before 1960

50-

60

1961-1973

25-

30

1974-1987

5-

10

After 1988

10

20

Fig. 5.3. Climate variability: current state and under climate change scenarios. The cross in the centre of each box corresponds to the mean annual values of temperature and precipitation, box length and height equals to two standard deviations, whiskers' outermost points are absolute maximum/minimum of the corresponding variable.

Fig. 5.3. Climate variability: current state and under climate change scenarios. The cross in the centre of each box corresponds to the mean annual values of temperature and precipitation, box length and height equals to two standard deviations, whiskers' outermost points are absolute maximum/minimum of the corresponding variable.

is not used for agriculture. However, the excess water in winter does not reach the Aral Sea. The water flows into an isolated Arnaysay depression, creating a system of lakes totalling 2000 km2 in area and raising the groundwater table. As a result, there are widespread newly formed swamps, covering an area of over 20,000 km2 in the Arnaysay depression.

Besides these expected changes as a result of internal socio-economic and policy factors, external changes such as climate change (CC) will have an impact on water resources and thus also on the socio-economic situation (UNFCCC, 1999, 2001). We will discuss the possible impacts of CC and assess some adaptations that will allow water managers to cope with these impacts.

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