Evolution of the hydro-climate system in the Lake Baikal basin

Abstract

Selenga River Basin Climate change CMIP5 Hydrology Permafrost s u m m a r yClimatic changes can profoundly alter hydrological conditions in river basins. Lake Baikal is the deepest and largest freshwater reservoir on Earth, and has a unique ecosystem with numerous endemic animal and plant species. We here identify long-term historical ) and projected future hydro-climatic trends in the Selenga River Basin, which is the largest sub-basin (>60% inflow) of Lake Baikal. Our analysis is based on long-term river monitoring and historical hydro-climatic observation data, as well as ensemble mean and 22 individual model results of the Coupled Model Intercomparison Project, Phase 5 (CMIP5). Study of the latter considers a historical period (from 1961) and projections for 2010-2039 and 2070-2099. Observations show almost twice as fast warming as the global average during the period 1938-2009. Decreased intra-annual variability of river discharge over this period indicates basin-scale permafrost degradation. CMIP5 ensemble projections show further future warming, implying continued permafrost thaw. Modelling of runoff change, however, is highly uncertain, with many models (64%) and their ensemble mean failing to reproduce historical behaviour, and with indicated future increase being small relative to the large differences among individual model results.

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

“…In the high mountain river basins of the Northern Tien Shan, for example, glacier melt contributes 18-28% to annual runoff and up to 70% to summer runoff (Aizen et al 1996;Dikich and Hagg 2003). Moreover, there is observational evidence that large-scale permafrost thaw in mountain regions of Central Asia has decreased the annual maximum flows and increased the annual minimum flows (Törnqvist et al 2014), due to a dampening effect of increased groundwater storage in areas of reduced permafrost. In particular, decreased maximum flows may have large impacts beyond the mountain regions, due to the importance for basin-wide sediment and pollutant transport Pietroń et al 2015;Thorslund et al 2016).…”

“…However, global climate models are known to perform poorly in the region and tend to overestimate precipitation (Malsy et al 2013;Mannig et al 2013;Bring et al 2015). Therefore, there is a considerable uncertainty about both the direction and magnitude of future precipitation change, with current global circulation models unable to reproduce recently observed changes (Bhend and Whetton 2013;Törnqvist et al 2014). For several Central Asian rivers, it is nevertheless predicted that the combined effects of water withdrawals and climate change are likely to lead to a reduced streamflow in the future Malsy et al 2016;Stone 2008;Varis 2014).…”

Speciation and hydrological transport of metals in non-acidic river systems of the Lake Baikal basin: Field data and model predictions

“…Additionally, hydrological processes may transport metals to downstream regions with different environmental conditions. Changing environmental conditions within the Lake Baikal basin is still a research area with many unknowns, for example regarding hydroclimatic and permafrost changes (Törnqvist et al 2014).…”

“…The combined influences of land use alterations (the expansion of mining areas) and projected climate changes (the expected increased frequency of peak flow events; Altansukh and Davaa 2011;Törnqvist et al 2014) will likely result in increased discharge and erosion in the Lake Baikal drainage basin. Therefore, the transport of metals from the Zaamar site to the connected river systems will also likely increase.…”

Water Balance and Level Change of Lake Babati, Tanzania: Sensitivity to Hydroclimatic Forcings

“…From sunshine duration estimates in this world region [28], cloud cover can be expected to be between 0.3 and 0.5. Furthermore, from analyses of different hydroclimatic regions (including tropical, temperate and arid conditions), X c has been found to range between 0.7 and 1.2 [12,47,[52][53][54]. This reflects an error in the estimated evapotranspiration on the order of 20% to 30%, which e.g., is lower Model parameters (Table 1) were, to a large extent, independently derived from available meteorological, hydrogeological and lake level records, as described in previous sections.…”