Initial Characterization and Water Quality Assessment of Stream Landscapes in Northern Mongolia

Abstract

A comprehensive monitoring project (2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013) provided data on hydrology, hydromorphology, climatology, water physico-chemistry, sedimentology, macroinvertebrate community and fish diversity in the Kharaa River basin in northern Mongolia, thus enabling, for the first time, a detailed characterization of the stream landscapes. Surface waters were categorized into separate "water bodies" according to their identifiable abiotic and biocoenotic features, subsequently creating the smallest management sub-units within the river basin. Following the approach of the European Water Framework Directive (EC-WFD), in order to obtain a good ecological status (GES), four clearly identifiable water bodies in the Kharaa River main channel and seven water bodies consisting of the basin's tributaries were delineated. The type-specific undisturbed reference state of various aquatic ecosystems was identified in the assessment and used to set standards for OPEN ACCESSWater 2015, 7 3167 restoration goals. With regards to water quality and quantity, the upper reaches of the Kharaa River basin in the Khentii Mountains were classified as having a "good" ecological and chemical status. Compared with these natural reference conditions in the upper reaches, the initial risk assessment identified several "hot spot" regions with impacted water bodies in the middle and lower basin. Subsequently, the affected water bodies are at risk of not obtaining a level of good ecological and/or chemical status for surface waters. Finally, a matrix of cause-response relationships and stressor complexes has been developed and is presented here. The applicability of management approaches is discussed to better foster the development of a sustainable river basin management plan. The application of natural references states offers a sound scientific base to assess the impact of anthropogenic activities across the Kharaa River basin.

Science-Based IWRM Implementation in a Data-Scarce Central Asian Region: Experiences from a Research and Development Project in the Kharaa River Basin, Mongolia

“…Results of nutrient emission modeling confirm that urban settlements are the main sources for nitrogen and phosphorus emissions [44][45][46]. Since only 35% of the total population in the river basin is connected to wastewater treatment plants (WWTPs), unconnected urban areas represent an important proportion of the total emissions.…”

“…These eleven water bodies could be assigned to five river types, comparable to the European river typology. Type-specific reference conditions could be identified [46]. Scientific information on the state of aquatic ecosystems did not exist.…”

“…A comprehensive inventory of the aquatic fauna, physico-chemical and hydromorphological parameters was used to develop reference based ecological assessment tools incorporating several biological indicators and metrices [46]. An initial assessment revealed river sections being at risk of failing the good ecological status.…”

“…Compared to the natural reference conditions in the Khentii Mountains (water body Kh_Trib_2 in Figure 4) the phosphorus enrichment is clearly visible, particularly after the confluence of the Zagdalin Gol (water body Kh_Trib_5) with the main channel of the Kharaa River (water body Kh_Main_4). Based on the long-term series of discharge and water quality measurements, the resulting loads could be calculated for the river basin outlet, showing evidence for a continuous increase of phosphorus concentrations [46].…”

“…River-bank erosion was identified as the predominant fine sediment source [47,48]. For the period 2007 to 2013, the transport loads of sediments, nutrients, heavy metals, and sediments were calculated based on water quality and hydrological data [37,[44][45][46].…”