Hourly surface meltwater routing for a Greenlandic supraglacial catchment across hillslopes and through a dense topological channel network

Abstract. Recent work has identified complex perennial supraglacial stream and river networks in areas of the Greenland Ice Sheet (GrIS) ablation zone. Current surface mass balance (SMB) models appear to overestimate meltwater runoff these compared in-channel measurements discharge. Here, we constrain SMB using hillslope routing model (HRR), a spatially explicit flow used terrestrial hydrology, 63 km2 catchment southwest Greenland. HRR conserves water momentum explicitly accounts for (i.e., over ice and/or firn on GrIS), produce hourly flows nearly 10 000 channels given inputs an digital elevation (DEM), remotely sensed channel network, SMB-modeled runoff, situ discharge dataset calibration. Model calibration yields Nash–Sutcliffe efficiency as high 0.92 physically realistic parameters. We confirm earlier assertions that exceeds conserved measured this (by 12 %–59 %) large do not dewater overnight despite diurnal shutdown production. further test network density controls conclude including through fine-channel (as opposed excluding coarse-channel network) produces most accurate results. Modeling processes is thus both possible necessary accurately simulate timing magnitude flows, highlight need additional datasets better calibrate apply method elsewhere sheet.