Changes in snowmelt flooding and driver factors in the China-Pakistan Economic Corridor

Flooding is one of the most frequent disasters in the China-Pakistan Economic Corridor (CPEC), which is highly dangerous and destructive, and seriously hinders regional socio-economic development. In this study, the Block Maximum (BM) model and the Peak Over Threshold (POT) model were used to analyze the spatial and temporal characteristics of snowmelt floods in the Kashgar River Basin and the Indus River Basin of CPEC during 1948–2022. Historical floods were classified based on principal component analysis and the k-means clustering algorithm. The main climatic factors of snowmelt floods were analyzed using Spearman’s rank correlation coefficient and random forest model. The results indicated that 85 and 93 snowmelt flood events occurred respectively in the two basins, mainly in spring (March–May). The occurrence of snowmelt floods was advanced in the Kashgar River Basin, while that in the Indus River Basin was delayed. Five and four flood classes were identified in the Kashgar River Basin and the Indus River Basin, respectively. Attribution analysis suggested that the snow factors are key preconditions, especially the 14-day antecedent maximum SWE (MSWE). The Kashgar River Basin was more sensitive to 7-day cumulative precipitation (CPr7) from 1982 to 1999, but to 7-day cumulative daily average temperature (TEMP7) from 2000 to 2020. The Indus River Basin was more sensitive to 1-day cumulative precipitation (CPr1) from 1982 to 1999. However, the impact of CPr7 on snowmelt floods increased from 2000 to 2020. The study provides scientific and technological support for snowmelt flood forecasting and prevention in CPEC and regional disaster prevention and mitigation efforts.