Streamflow reconstruction using tree rings is crucial for understanding the long-term hydrological variability, particularly in data-scarce regions like the Upper Indus River Basin (UIRB), in northern Pakistan. This information is essential for managing water resources, assessing climate change impacts, and supporting hydropower generation. Instrumental streamflow records in this region are limited in length, thus emphasizing the need for alternative approaches like dendrohydrology. Besham Qila gauging station is a vital monitoring point of the River Indus as it represents 100% of the UIRB discharge. The objective of the current study was to reconstruct mean annual streamflow for the Besham Qila gauging station, located at the main Indus River, using the regional tree-ring chronologies as predictors in a step wise linear regression model. The analysis successfully explained 63% of the variance in the instrumental discharge. The reconstruction extended the streamflow record to four centuries from the year 1593-1993, and revealed range of hydrologic extremes, encompassing both high and low flow conditions. These findings may have important implications for water resource management of the region and predicting future changes in the river's flow. Future research will focus on integrating tree-ring data with other proxy records to enhance our understanding of hydrological variability and support informed decision-making for water resource management in the UIRB.

Keywords- tree ring chronology, Upper Indus Basin, streamflow reconstruction, Besham Qila