Abstract ID: 3.13193 | Not reviewed | Requested as: Talk | TBA | TBA

There is no environmental information available for the Khentii Mountains in Mongolia. In a highly continental climate, the ecotone of boreal forests turns into semi-arid steppe. The mountain range is of paramount importance for the water supply of its forelands. To better understand the hydrology, we started field studies 10 years ago, under challenging environmental conditions. The investigated catchment covers 480 km² and ranges from 800 to 2700 metres.
The central question of our investigations was whether we could reliably reproduce the water availability and hydrological dynamics of the basin using a combination of measured point data, detailed knowledge of the catchment physiography, global data products and hydrological modelling. Further analysis should also show whether the increased occurrence of forest fires has had an impact on the hydrology of the region.
We operate monitoring stations in the catchment to document climatological variables, soil moisture and soil temperatures. Measurement campaigns recorded key parameters for hydrological modelling, such as soil properties, forest structure and leaf area index. In 2023, the areas affected by forest fires were intensively analysed.
The hydrological model TRAIN was applied to simulate the water balance. We used globally available products to characterise the region, drive the TRAIN model and later validate the simulations. Daily values from ERA5, MODIS, GLEAM, and SMAP were validated using our station data before they were fed into TRAIN. The results show that the model forcing data reasonably reflects the climatic conditions. The agreement between the simulated values of evapotranspiration (ETA) and root soil zone moisture (RZSM) and data provided by the global products can be described as good overall, although there are significant deviations in individual years. The studies show that there has been a pronounced decrease in precipitation over 1980-2022 and that simulated runoff, RZSM and ETA have all decreased, in some cases drastically. It also shows that the areas affected by forest fires have reached a size that influences the hydrology of the basin. Overall, the combination of the above methods has led to a significant increase in knowledge and the water balance of the region can be determined with reliable accuracy.