Natural Water Quality and Its Suitability in the Northern Tianshan Catchments (Central Asia)

Abstract

The use of water resources in arid lands is strongly limited by their quantity. To add to such knowledge, this study evaluates the natural water quality and its suitability for drinking, agricultural and industrial purposes in the northern Tianshan catchments (Central Asia), using chemical-physical indicators. The waters are neutral to alkaline and most of them are soft-fresh waters. The total dissolved solid (TDS) varies over two orders of magnitude. Much of the solutes and physicochemical parameters in water are under the highest desirable limits of the World Health Organization (WHO) for drinking purpose and most waters are of good water quality for irrigation. The effects of local pollution are minimal in the montane and piedmont areas of these watersheds but are significant in the oases and central areas of the drainage basins. Although the headwaters of the northern Tianshan catchments represent natural background conditions (soft-fresh water in salinity and hardness) and population densities within the catchment are relatively low, the river basin is facing relatively high anthropogenic pressure on water quality in the low reaches. The main contributors to the nutrient emissions are agricultural land use and, to a lesser extent, unban settlements with a high proportion of households without connection to wastewater treatment plants. Proposals for regional water resources management are advised, i.g. the geographic data and information should be detailedly included in the assessment and monitoring procedure, a water quality model should be built, and information technology such as visualization technology and the internet should be used.