The Tuul River Basin is the most important socioeconomic and political base area of Mongolia. Therefore, studying the interrelationships between changes in the ecohydrological processes of this basin and its land cover is of great importance for maintaining sustainability and the environment. This study investigated the annual average air temperature, total annual precipitation, and river discharge variability, and land cover changes at selected stations of the basin by using the hydrometeorological analysis, satellite analysis, and land cover determination statistical analysis. During the study period, the average annual air temperature rose from −1.5 °C to +0.3 °C (1.8 °C 361 °C). The average annual precipitation exhibits relatively low change during this period. River discharge varied during the study period. A significant decreasing trend in river discharge was observed at the Terelj (φ = −2.72) and Ulaanbaatar (φ = −5.63) stations, whereas the other stations, Altanbulag, Lun, and Orkhontuul, showed a significant increasing trend. During the study period, changes in land cover were directly related to main hydrometeorological parameters. Between 2000 and 2020, the amount of grassland decreased by 319.67 km2, while the area of water bodies increased by 28.36 km2. In the study area, mainly water bodies and sensitive areas of the land cover types were changed due to changes in precipitation. Studies in the arid and semiarid regions of Central Asia show that changes of ecohydrological processes have a significant impact on land cover changes.

Wildfire is a natural disaster that harms human and animal habitats and the socio-economy. Remote sensing techniques are commonly used in the research of natural disasters, natural resources and monitoring. Timely and accurate estimation of the location of forest fires is particularly important for post-fire management and decision-making. Sentinel-2 satellite images of the European Space Agency ‘ESA’ were used to estimate the area affected by forest fires at Bayan-Uul and Bayandun soums in Dornod province, and classified the burn severity levels and comparison with other influencing factors in this study.  The normalized burn ratio ‘NBR' and indices on pre-fire and post-fire were calculated.  The total burned area was calculated as 58,131.6 ha, and low, moderate-low, moderate-high, and high burn severity levels cover 15,423.7 ha (26.3%), 29,529.4 ha (50.4%), 13,160.2 ha (22.5%), and 18.3 ha (0.03%), respectively. The 87.6% of the burned area is situated in Mongolian territory, while the remaining area (12.4%) belongs to the Russian Federation. Comparing 10 natural and geographical factors that can influence the burn severity and calculating the correlation coefficients by Pearson.  Four of them related a positive lower, and six of them related negative lower. The weak relationships of Normalized Difference Vegetation Index ‘NDVI’, elevation were 0.4 and 0.23. However, the precipitation correlation was -0.22 (negative weak). The distribution of wildfire is strongly influenced by the wind, and the correlation coefficient demonstrates a negative correlation with no effect on combustion. The conditions of socio-economic and ecological disastrous consequences such as loss of plant species and resources, changes in plant structure, depletion of pasture resources, extinction of rare animals and plants, reduction of forest resources, and large-scale air pollution resulting in the loss of human and animal in post-fire. Therefore, this research is important to due for studying the burning, distribution and, coverage area of the fire, and create conditions for the prevention of future risks.

No abstract