Integrated water resources management in central Asia: nutrient and heavy metal emissions and their relevance for the Kharaa River Basin, Mongolia

摘要

Within the framework of Integrated Water Resources Management (IWRM) the nutrient and heavynmetal levels within the Kharaa river basin were investigated. By the application of the MONERISnmodel, which quantifies nutrient emissions into river basins, various point and diffuse pathways,nas well as nutrient load in rivers, could be analysed. Despite seasonal variations and inputs ofnpoint sources (e.g. Wastewater Treatment Plant Darkhan) the nutrient concentrations in most ofnthe subbasins are on a moderate level. This shows evidence for a nutrient limited ecosystem asnwell as dilution effects. However, in the middle and lower reaches heavy metal concentrations ofnarsenic and mercury, which are linked to mining activities in many cases, are a point of concern.nThus measures are necessary to protect the valuable chemical and ecological status of thenKharaa River and its tributaries. As a result of the growing economic pressure Mongolia willnenhance the agricultural production by irrigation. Until 2015 about 60% of the agricultural landnshall be irrigated. In addition the gold mining activities shall increase by 20% a year. Both sectorsnhave a high demand for water quantity and quality. The model MONERIS allows the assessmentnof measures which are inevitable to protect the water quality under shrinking water availability.