Impact of climate change and water regime in the Khovd River basin

Ховд голын сав газрын уур амьсгалын өөрчлөлт ба усны горимд үзүүлэх нөлөө

Abstract

The study covers climate change and its impact on the flow regime in the Khovd River Basin, which originates from the glacier valley of the southwestern valley of Tavan Bogd Mountain in the Mongolian Altai Mountains. Mann-Kendall analysis (MK), Innovative Trend Analysis Method (ITAM), and Sen’s Slope Estimator Test (SSET) were used for runoff and impact analysis in this study. The basin evapotranspiration is estimated by the Blaney-Cridle method (BC) and also some other statistical analysis methods were used in this study. Concerning used, data on climate and flow series from hydrological and meteorological stations located in the in Bayannuur, Nogoonnuur, Olgii, Yalalt, and Khovd sum of Bayan-Olgii provinces. The climate and water flow data for 1990-2020 were used in Bayannuur, Nogoonnuur, Olgii, Yalalt, and Khovd sum of Bayan-Olgii province. According to the results of the research, the flow series along the Khovd river has a decreasing trend for the last 30 years (1990-2020). This trend is certainly impacted by climate change in the river basin. During the past 30 years of climate change, the average annual air temperature has increased by 0.78^oC in the Khovd river basin. The total annual precipitation in the Khovd river basin is estimated to be 127.3 mm. Although the rainfall variability is relatively low, the sum of annual precipitation was below the regional long-term mean in the last 10 consecutive years. The estimated average basin evapotranspiration during the warm season is estimated to be about 130.5 mm in the basin. The precipitation and its change have a key impact on the flow of the Khovd river in terms of climate change and according to the studies, river, precipitation amount is almost unchanged in the basin. However, the air temperature value increases by 0.026 degrees every year and due to the increase of evapotranspiration rate, caused by air temperature increase, river flow in the basin is reducing in the last 30 years, from 1990 to 2020.