Simulating Runoff Regime in a Glaciated High-Mountainous Basin: A Case Study of the Baksan River (Caucasus, Russia)

Abstract

The water resources of the North Caucasus depend mostly on the state of glaciers, which have been intensely losing their mass in the recent decades against the background of climate changes. The deglaciation leads not only to a decrease in the glacier runoff of mountain rivers, but also to changes in the annual distribution of runoff. The focus of this study is the adaptation of ECOMAG software complex to simulating river runoff in the Baksan River basin based on data on the relief and underlying surface of the drainage basin (soil, vegetation) and daily data on the surface air temperature, air saturation deficit, and precipitation. The calibration and validation of the model and the statistical estimate of calculation efficiency were based on the data on water discharges in the Baksan River over 2000–2017. The developed model of runoff formation in the Baksan River basin was used to carry out numerical experiments for assessing the sensitivity of runoff characteristics to glacier area variations. Depending on the rate of deglaciation process, the runoff of the Baksan River can drop by 10–30% because of a decrease in its glacial component, and the maximal water discharges can drop by 10–15%.