28 - Water regime management of desertificated ecotone systems in the Amudarya delta (Aral Sea basin)

Summary

ABSTRACT Regularities of the changes of ecosystems of the ecotones of stream and lake banks under the natural evolution of landscapes in the Amudarya delta are studied. Regimes of flooding and groundwater, typical to each stage of development, are revealed. Investigation of the modern conditions for two types of ecotone ecosystems (wetland and terrestrial) enable us to determine the degree of their desertification. The main concept of water regime management is to protect the biological diversity by means of conservation of all the variants of land – water ecotone systems.

Based on the present-day state-of-the-art of lake and tugai ecosystems in the Amudarya river delta, recommendations on their watering are developed to guarantee optimum functioning or rehabilitation of the ecosystems.

INTRODUCTION

The Aral Sea is situated in the centre of Turan desert area in Central Asia. Its water balance depends on the Amudarya and Syrdarya rivers inflow. Historically, the Aral Sea region has been desertified on several occasions. Recent desertification is a human-induced phenomenon brought about mainly by overuse of river flow in the middle and upper reaches of the Amudarya and Syrdarya rivers for the needs of developing irrigation. That leads to a lack of available water resources in deltas. Decreasing the input of the river water in the Aral sea and in the Amudarya and Syrdarya river deltas reached its critical means in 1960, where the main reservoirs was built and the irrigated area in the Aral Sea basin became 1 × 10⁶ ha. Since this time the Aral Sea level has dropped from the absolute elevation of 53 metres to 30 metres in 1991.