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The surface water hydrochemistry of the Syr Darya River in Kazakhstan was investigated at 39 locations to analyze regional hydrochemical characteristics and evaluate the irrigation suitability of the studied regions. The cations in the surface water are mainly Na+, Ca2+, and Mg2+, while the anions are mainly SO42−. The main hydrochemical type is Ca-Mg-SO4-Cl. From the perspective of natural factors, the hydrochemical characteristics in the study area are derived from the dual effects of rock weathering and evaporation-concentration; however, the influence of anthropogenic factors include industrial and agricultural production near the river and the inflow of urban domestic sewage on the hydrochemical characteristic is also present. The irrigation suitability evaluation of the surface water based on SAR, Na% and KI showed that the majority of the water is suitable for irrigation, and from the TDS content analysis, 71.43% of the samples are in a critical state, indicating that the influence of TDS concentration on irrigation suitability cannot be ignored. The results have practical significance for maintaining the sustainable use of water resources in the Syr Darya River. Electronic supplementary material The online version of this article (10.1007/s10661-019-7713-8) contains supplementary material, which is available to authorized users.

Lakes of Kazakhstan are very numerous. There are 48,262 lakes in size of one hectare and above with a total surface area of 45,002 km2. This list is not included in Caspian and Aral Seas, ponds, reservoirs, and plexus lakes. Small lakes in size 1 km2 with an area of 40,769 km2 (90%) (Fig. 3.1). There are 20 lakes larger than 100 km2 and are with an area of 26,886 km2 (Fig. 3.1), which is 59% of the water surface of all lakes. The total volume of water in these natural bodies is 190 km3 (Fig. 3.2).

According to the conditions of water exchange, there are differentiated drainage, periodically sewage, sewage, and flowing lakes in the territory of Kazakhstan. Main of them are drainless. The components of the water balance of the drainless lakes (surface runoff, precipitation falling on the surface of the lake, groundwater, filtration, and evaporation) are subject to large intra-annual and long-term changes. They are in conditions of shallow water lead to a characteristic for Kazakhstan in inconstancy level, the drying out of a significant part of the water bodies in summer and autumn seasons, as well as in perennial low-water periods.

There are 1300 natural lakes in Tajikistan, with a total water surface area of 705 km2 and a total volume of about 50 km3.

The basis of the hydrographic system in Kyrgyzstan is the river systems and water catchments that are separated by watershed mountain ranges from each other (Fig. 8.1). The hydrographic system of river basins is made up of lakes, glaciers, groundwaters, swamps, and wetlands. All of them are products of orography, relief/topography, underlying surface, and climate. They have an interaction and mutual influence and take a direct part in the formation of the water balance of the river flow regime.

There are two river basins in Uzbekistan that form the Aral Sea Basin: The Amudarya and Syrdarya river basins. The Amudarya river basin covers 81.5% of the country’s territory. There are three sections of the river: (1) the upper course flowing along the border with Afghanistan and Tajikistan, where most of the water flow is formed; (2) the middle course, which first passes along the border of Uzbekistan and Afghanistan and then enters Turkmenistan, (3) as well as the lower course passing through the territory from Uzbekistan to the confluence of the Aral Sea.

This paper presented the results from the study of irrigation erosion of irrigated lands in southern Kazakhstan. The main purpose of the work is the conservation of the fertility of irrigated soils, and then the soils of the upper, middle and lower sections of the slopes at the experimental site were studied. Based on field investigations, authors studied the water resistance of aggregates of gray-brown soils and light gray soils before and after irrigation and qualitative indicators of changes in physical and chemical properties of structured soils in irrigation were determined by conventional methods of soil research. The results indicated that the changes in the physical properties of soils by using polymeric compounds created a fundamentally new opportunity to control water erosion of soils.