Rivers

High Mountain Asia supplies rivers that billions depend on, yet gauges are sparse and earlier assessments covered mainly high-altitude sub-catchments, leaving change along whole channels unmapped. Daily flow was reconstructed for 114,147 reaches from 2004 to 2019 by combining hydrologic modeling with satellite-derived discharge, resolving reach by reach what coarser work saw only in aggregate. Discharge rose significantly in 9.7% of reaches, skewed toward smaller tributaries, at a mean 8.3% per year, and 8% of reaches with existing or planned dams showed stream power rising 2.9% per year

Although there have been significant advances in river routing and sub-grid heterogeneity (i.e., tiling) schemes in Earth system models over the past decades, there has yet to be a concerted effort to couple these two concepts. This paper aims to bridge this gap through the development of a two-way coupling between tiling schemes and river networks in the HydroBlocks land surface model. The scheme is implemented and tested over a 1 arc degree domain in Oklahoma, United States.