Assessment of the Water Balance in the Karabakh and Eastern Zangezur Regions

The article assesses the elements of the water balance in river basins. Climate and landscape changes primarily affect the territory's heat-moisture balance and water resources. Methods of assessing water resources are one of the most reliable ways of determining the water balance. The water balance of river basins is determined by separating precipitation into three components: surface runoff, baseflow (underground river feeding) and actual evaporation from the basin surface. When assessing the water balance, the research took into account the influence of most factors affecting the area's heat and moisture conditions. Most of the information on land use and land cover (LULC) and morphometric factors was obtained through spatial imagery and digital elevation models (DEM). The climate input was based on data from existing hydrometeorological stations. Where no observations were available, climate indicators were reconstructed using the latest methods and technologies. The differences between the actual observations and the reconstructed climate variables were very small at up to ±10%, occurring in 81.4% of cases. To estimate the water balance of river basins for which there were no observations, surface runoff was calculated using runoff coefficients based on a synthesis of modern hydrological methods. Base flow was assessed using our proposed formula and actual evaporation was estimated by subtracting the sum of the surface runoff and base flow fractions from the amount of precipitation. Of the 547.3 mm of precipitation that fell on the study area during the average multi-year period, 75.7% (414.3 mm) was used for actual evaporation. Only 133.1 mm (24.3%) of the precipitation was used for total runoff, of which 67.46 mm was surface runoff and 65.58 mm was groundwater runoff. The water balance was also calculated separately for the main rivers in the study area, revealing significant differences in their surface and underground supply.