Combining satellite precipitation products and tree ring data for streamflow reconstructions: long-term surface water assessment in poorly gauged basin

It has been demonstrated in many river basins worldwide that short instrumental streamflow records can be augmented with tree ring data to obtain a better assessment of surface water availability. Yet, this approach is not immediately feasible in poorly gauged basins, where the available data are even too short to calibrate dendrohydrological models. To tackle this challenge, we adopt a novel two-stage approach, combining satellite precipitation products and tree ring data. Using three test catchments in Vietnam, we first calibrate a hydrological model (SWAT) using the most recent streamflow and rain gauge data (2010-2019). We then feed the calibrated models with two global precipitation products (MSWEP and CHIRPS) to extend the streamflow time series back as far as 1980. Finally, we use the extended streamflow record to calibrate a tree-ring-based reconstruction model, producing a streamflow record dating back to 1600. Results show that (1) the satellite precipitation-forced simulation match well with observations, and (2) the tree-ring-based reconstructions match well with both the satellite-based and instrumental time series. These encouraging results demonstrate the potential of combining global precipitation products and tree ring data for streamflow reconstruction in poorly gauged basins. This interdisciplinary approach also provides a promising venue toward more reliable assessments of surface water availability in developing countries.