Streamflow reconstruction for the Upper Indus Basin

The sustainability of water resources in Pakistan faces mounting challenges due to population growth, climate change, and declining groundwater reserves. The Indus River, vital for the country’s agriculture, energy, and economy, suffers from limited instrumental discharge records that do not capture long-term hydrologic variability or extreme flow events. This study addressed this gap by developing streamflow reconstructions for the Upper Indus Basin (UIB) using tree-ring chronologies (TRC) combined with sea surface temperature (SST) data—an approach not previously applied in this region—for four discharge stations: Partab, Daniyor, Besham Qila, and Kachora. Stepwise linear regression models using TRC and SST predictors explained 81 %, 70 %, 71 %, and 56 % of the variance in the instrumental data for Kachora, Partab, Besham Qila, and Daniyor, respectively. The results indicated strong linkages between Pacific and Atlantic Ocean climate variability and UIB streamflow. Snowmelt-dominated flows showed greater sensitivity to Atlantic SST, while glacier- and mixed-flow regimes were more closely associated with Pacific SST. These findings provide valuable insights for water managers and policymakers to support effective planning and management of UIB water resources. The methodology is readily transferable to other data-scarce mountain watersheds.