Daniel Karthe

Water resources and their management in central Asia in the early twenty first century: status, challenges and future prospects

Large parts of Central Asia are characterized by a semiarid to arid climate. Therefore, areas close to shallow groundwater, rivers and lakes are characterized by unique water-dependent ecosystems and human societies which have developed over millennia in close interaction with the naturally limited water resources. In the early 21st century, global climate change, population growth, river damming, large-scale water abstractions and rising levels of pollution exert multiple pressures on the region’s water resources, aquatic and terrestrial ecosystems at historically high levels. Water scarcity threatens the livelihood of populations locally and in transboundary settings by a growing competition over a limited resource. This context is of particular importance since all major rivers of the region cross at least one international border. The complexity and character of water-related challenges in the region mean that management approaches need to be integrative, taking into account the natural resource basis, environmental limits and the socio-cultural and geopolitical dimension. This paper frames the thematic issue of Environmental Earth Sciences and provides a comprehensive overview about the current state of knowledge about water resources and their management in Central Asia. There is a focus on case studies looking at the Selenga–Baikal–Angara Basin, the Lake Aral Basin including the Syr Darya and Amu Darya river systems, the Tarim and the Illi River Basins. Aiming to be an up-to-date interdisciplinary scientific reference on the region’s water-related challenges, this thematic issue gives theoretical and practical insights into solutions and best practice examples of water management.

IWRM in a country under rapid transition: lessons learnt from the Kharaa River Basin, Mongolia

Abstract Since it is representative in terms of environmental and socioeconomic conditions, the Kharaa River Basin in Northern Mongolia was chosen as a Central Asian model region for the development and implementation of a science-based IWRM approach. While a highly continental climate results in limited water availability, the combined effects of climate and land use changes and rising water consumption are likely to intensify quantitative and qualitative water scarcity. In such a context, water contamination due to deficient treatment of domestic, industrial and mining-related waste waters is particularly critical, putting at risk human health and aquatic ecosystems. In the recent past, water governance structures in transitional countries like Mongolia have not permitted to respond effectively to such complex challenges. For the model region of the Kharaa River Basin, considerable improvements in the scientific basis are currently coinciding with political reforms incorporating science-based river basin management as a guiding principle. This paper provides an integrative assessment of recent advancements which form the scientific basis for a future IWRM implementation in the region.

INTEGRATING MULTI-SCALE DATA FOR THE ASSESSMENT OF WATER AVAILABILITY AND QUALITY IN THE KHARAA—ORKHON—SELENGA RIVER SYSTEM

The environmental and socio-enonomic impacts of water pollution are particularly severe in regions with relatively limited water resources [WWAP, 2012]. Water quantity and quality are closely interlinked aspects which are relevant for surface water ecology, water use, and integrated management approaches. However, an intensive monitoring of both is usually prohibitive for very large areas, particularly if it includes the investigation of underlying processes and causes. For the Kharaa - Orkhon - Selenga River system, this paper combines results from the micro (experimental plots, individual point data), meso (Kharaa River Basin) and macro (Selenge River Basin) scales. On the one hand, this integration allows an interpretation of existing data on surface water quantity and quality in a wider context. On the other hand, it empirically underpins the complimentary character of intensive monitoring in selected model regions with more extensive monitoring in larger areas.

Assessment of runoff, water and sediment quality in the Selenga River basin aided by a web-based geoservice

The Selenga River is the main artery feeding Lake Baikal. It has a catchment of ~450000 km² in the boundary region between Northern Mongolia and Southern Siberia. Climate, land use and dynamic socioeconomic changes go along with rising water abstractions and contaminant loads originating from mining sites and urban wastewater. In the future, these pressures might have negative impacts on the ecosystems of Lake Baikal and the Selenga River Delta, which is an important wetland region in itself and forms the last geobiochemical barrier before the Selenga drains into Lake Baikal. The following study aims to assess current trends in hydrology and water quality in the Selenga-Baikal basin, identify their drivers and to set up models (WaterGAP3 framework and ECOMAG) for the prediction of future changes. Of particular relevance for hydrological and water quality changes in the recent past were climate and land use trends as well as contaminant influx from mining areas and urban settlements. In the near future, additional hydrological modifications due to the construction of dams and abstractions/water diversions from the Selenga’s Mongolian tributaries could lead to additional alterations.

Modular Concept for Municipal Water Management in the Kharaa River Basin, Mongolia

Mongolia is a country with limited water resources but a rising water consumption due to an increasing population, urbanization and economic growth, which is largely driven by a booming mining sector. These processes do not only lead to greater water abstractions, but also contribute to water quality and aquatic ecosystem deterioration. Urban areas play a key role in this context, since water abstractions and waste water generation are concentrated here. However, there are considerable disparities between urban centers with centralized water supply and sewage infrastructures and peri-urban regions. Where existant, infrastructures for drinking water supply and wastewater collection and treatment are often in a poor state of maintenance, leading to the contamination of groundwater and surface water bodies with pathogens, nutrients, and other chemical substances. This paper presents components of a modular concept for urban water management at the example of Darkhan Uul Aimag, which were developed and pilot-tested in the context of a project aiming at the development and implementation of an integrated water resources management (IWRM) for the North Mongolian Kharaa River Basin. It is discussed how solutions were adapted to local situations, considering both sustainable resource utilization and local acceptance.

Modular development of an inline monitoring system for waterborne pathogens in raw and drinking water

Abstract The state-of-the-art monitoring of drinking water hygiene is based on the cultivation and enumeration of indicator bacteria. Despite its proven reliability, this approach has the disadvantages of being (a) relatively slow and (b) limited to a small number of indicator bacteria. Ideally, alternative methods would be less time-consuming while providing information about a larger set of hygienically relevant microorganisms including viruses. In this paper, we present insights into the design of a modular concentration and detection system for bacteria, bacteriophages and viruses. Following further validation, this or similar techniques have the potential to extend and speed up the monitoring of raw and drinking water hygiene in the future. The system consists of different modules for the concentration of microorganisms, an amplification and detection unit that includes a module for the differentiation between live and dead microorganisms, and an automated system for decision support and self-diagnosis. The ongoing testing under controlled laboratory conditions and real-life conditions in the water supply industry yields further system improvements. Moreover, the increased sensitivity and broader range of microbiological parameters emphasize the need for a reconsideration of the currently used criteria for the assessment of (drinking) water hygiene.

Regional disparities of microbiological drinking water quality: assessment of spatial pattern and potential sociodemographic determinants

Abstract Even in industrialized countries like Germany, drinking water quality is a sensitive issue. Despite a generally high level of drinking water safety, contamination events do occur. We address the question whether demographic change may cause a spatial mismatch between installed capacities at the supply side and actual demand by water users, thereby increasing risks of microbiological contamination. Our investigation is based on a quantitative analysis using the largest publically available data-set on drinking water quality in Germany. We found that the number of reported contamination events in areas affected by population decrease was about twice as high as in areas with a stable or growing population. The relative frequency of microbiological contamination was found to be significantly correlated with rapidly depopulating areas. We conclude that in regions with negative population development, a statistically higher risk of microbiological drinking water contamination may coincide with a greater risk of recontamination during a longer passage in the distribution network.

Environmental change in the Selenga River—Lake Baikal Basin

Lake Baikal’s most important tributary is the Selenga River, which contributes about 50 to 60% of its surface water influx (Chalov et al. 2015; Opp 1994; Törnqvist et al. 2015). Moreover, the Selenga’s 447.060-km watershed covers 82% of the Lake Baikal Basin (Nadmitov et al. 2014) (Fig. 1), which means that any environmental changes along the Selenga and its tributaries may ultimately impact Lake Baikal. However, north of the Buryatian capital Ulan Ude, the Selenga River branches into the largest freshwater inland delta in the world (Logachev 2003). The associated wetland constitutes a unique ecosystem (Гармаев and Христофоров 2010) and acts as the final geobiochemical barrier before the Selenga discharges into Lake Baikal (Chalov et al. 2016). Therefore, it has a great impact on pollution delivery to Lake Baikal, storing up to 60–70% of the sediment load of the Selenga River (Chalov et al. 2017). The protection of Lake Baikal and the planning of water management measures in the Selenga river basin require a good understanding of current trends regarding hydrology, water quality, aquatic and riparian zone ecology of the Selenga and its key tributaries (Karthe et al. 2016), and geoand biochemical processes governing the ecological functioning of the Selenga delta (Khazheeva et al. 2004). The following anthropogenic impacts constitute threats to the ecology of the Selenga from its tributaries down to its delta: Various mining activities are found in the Selenga river basin, including the exploitation of coal, gold, copper, molybdenum and wolfram (Sandmann 2012; Timofeev et al. 2015). As a consequence, elevated levels of heavy metals and other mining-related pollutants (cyanides, phosphorus) have been detected in the water and sediments of the Selenga and its tributaries, as well as floodplain soils and groundwater (Battogtokh et al. 2014; Brumbaugh et al. 2013; Chalov et al. 2015; Inam et al. 2011; McIntyre et al. 2016; Nadmitov et al. 2014; Pavlov et al. 2008; Pfeiffer et al. 2015; Stubblefield et al. 2005; Thorslund et al. 2012). Even though contaminant transport towards the Selenga delta does take place (Chalov et al. 2015; Khazheeva et al. 2004; Karthe et al. 2014), it should be noted that contaminations currently have the largest effects in local hot spots (Hofmann et al. 2010; Inam et al. 2011; Pfeiffer et al. 2015). Currently, there are different views regarding their impact on Lake Baikal itself (Chebykin et al. 2010; Pavlov et al. 2008). However, bioaccumulation and toxicological effects observed in aquatic biota ranging from insects to fish provide indication that water quality deterioration in the Selenga river system does have an ecological impact (Avlyush 2011; Kaus et al. 2016; Komov et al. 2014). * Sergey Chalov hydroserg@mail.ru

Chemical water quality gradients in the Mongolian sub-catchments of the Selenga River basin

Even though the Selenga is the main tributary to Lake Baikal in Russia, the largest part of the Selenga River basin is located in Mongolia. It covers a region that is highly diverse, ranging from almost virgin mountain zones to densely urbanized areas and mining zones. These contrasts have a strong impact on rivers and their ecosystems. Based on two sampling campaigns (summer 2014, spring 2015), we investigated the longitudinal water quality pattern along the Selenga and its tributaries in Mongolia. While headwater regions typically had a very good water quality status, wastewater from urban areas and impacts from mining were found to be main pollution sources in the tributaries. The highest nutrient concentrations in the catchment were found in Tuul River, and severely elevated concentrations of trace elements (As, Cd, Cu, Cr, Fe, Mn, Ni, Pb, Zn), nutrients (NH4+, NO2−, NO3−, PO43−), and selected major ions (SO42−) were found in main tributaries of Selenga River. Moreover, trace element concentrations during spring 2015 (a time when many mines had not yet started operation) were markedly lower than in summer 2014, indicating that the additional metal loads measured in summer 2014 were related to mining activities. Nevertheless, all taken water samples in 2014 and 2015 from the main channel of the Mongolian Selenga River complied with the Mongolian standard (MNS 1998) for the investigated parameters.

Water in Central Asia: an integrated assessment for science-based management

Central Asia contains one of the largest internal drainage basins in the world, and its continental location results in limited availability of both surface and groundwater. Since the twentieth century, water resources of the region have been exploited beyond sustainable levels. From small Mongolian headwater streams to the mighty Aral Sea, surface waters have been partially desiccated. Demands from the agricultural, energy and raw material sectors as well as population growth have not only increased water abstractions, but also left a diverse and strong pollution footprint on rivers, lakes and groundwater bodies. Such changes in water quantity and quality have not only led to a degradation of aquatic and riparian ecosystems, but also they have placed the region’s socioeconomic development at risk. Because of the complexity of Central Asia’s water problems, integrated assessment and management approaches are required. Despite some shortcomings in practical implementation, the widespread adoption of the Integrated Water Resources Management and water–food–energy nexus approaches may be keys to a more sustainable future. This thematic issue aims to provide documentation of the current state of scientific knowledge, ranging from hydrological research to water quality investigations, and offers an assessment of ecosystems and the services provided by them. Reviews and case studies on different management options conclude the thematic issue by providing insights into field-tested solutions for the region’s water challenges.