SPATIAL ASSESSMENT AND ANALYSIS OF MUDFLOW HAZARD ZONES IN THE SURKHANDARYA RIVER BASIN USING GIS AND REMOTE SENSING-BASED STATISTICAL MODELS

Mountainous and foothill regions of Surkhandarya Province (Uzbekistan) are increasingly affected by mudflow events driven by climate change, glacier retreat and intense seasonal rainfall. This study presents a spatial assessment of mudflow hazard zones in the Surkhandarya River basin (13 500 km²) using an integrated GIS and remote sensing approach. A geospatial database of 115 mudflow inventory points (2022-2024) was compiled and seven conditioning factors (TWI, SPI, rainfall, drainage density, lithology, NDVI and slope aspect) were standardized at 30 m resolution. Hazard zonation was carried out using the Frequency Ratio (FR) model, validated with ROC/AUC analysis (AUC=0.856). The study area was classified into five hazard categories. Results indicate that the very high hazard zone covers 265.17 km², of which 60% lies in Tajikistan (Tursunzoda district, 124.17 km²) and 40% in Uzbekistan (Sariosiyo district, 77.98 km²). Land cover analysis revealed that 163.05 km² of very high hazard areas overlap with cropland and 82.42 km² with settlements, highlighting the urgent need for risk reduction measures along the Karatag-Tupalang river confluence.