Remote Sensing-Based Extension of GRDC Discharge Time Series - A Monthly Product with Uncertainty Estimates

Abstract

The Global Runoff Data Center (GRDC) data set has faced a decline in the number of active gauges since the 1980s, leaving only 14% of gauges active as of 2020. We develop the Remote Sensing-based Extension for the GRDC (RSEG) data set that can ingest legacy gauge discharge and remote sensing observations. We employ a stochastic nonparametric mapping algorithm to extend the monthly discharge time series for inactive GRDC stations, benefiting from satellite imagery- and altimetry-derived river width and water height observations. After a rigorous quality assessment of our estimated discharge, involving statistical validation, tests and visual inspection, results in the extension of discharge records for 3377 out of 6015 GRDC stations. The quality of discharge estimates for the rivers with a large or medium mean discharge is quite satisfactory (average KGE value > 0.5) however for river reaches with a low mean discharge the average KGE value drops to 0.33.The RSEG data set regains monitoring capability for 83% of total river discharge measured by GRDC stations, equivalent to 7895 km3/month.

Benchmark Framework for Global River Model (Version 1.0)

“…Data coverage is especially limited in regions of Asia and Africa, where water resource scarcity and flood hazards are more pronounced (Kettner et al, 2021). The lack of recent data records after 1990s seriously undermines the reliability of model evaluations for the new environment with climate change and dense human activities (Elmi et al, 2024). Satellite remote sensing data has become increasingly popular for deriving water dynamic variables in recent years (Musa et al, 2015).…”