Spatiotemporal Dynamics of Slow-Flow Responses in Glaciated and Nonglaciated Catchments

Abstract

Slow-flow, the delayed component of streamflow, plays a critical role in water management in mountainous catchments. However, a comprehensive assessment of slow-flow through hydrologic signatures and linking it to catchment attributes has been less explored in Himalayan catchments. This study introduces the application of hydrologic signatures to characterize and interpret the slow-flow response obtained through numerical techniques. It was observed that glaciated catchments exhibit a significantly lower annual slow-flow contribution (65%) than nonglaciated catchments (72%), with declining trends tied to reduced snow cover dynamics. Meltwater sustains stable slow-flows in summer, unlike winter-dominated slow-flows in nonglaciated catchments driven by subsurface flow. The study shows that meltwater sustains more consistent (described by the slope of slow-flow duration curve) slow-flow periods in glaciated catchments, whereas slow-flows in nonglaciated catchments exhibit high variability linked to catchment attributes. The annual rainfall strongly drives the low to moderate regimes of slow-flows, and soil texture, bedrock depth, and snow cover control the temporal dynamics of slow-flows. These findings emphasize the need for improved understanding of the interactions among snow cover, catchment characteristics, and slow-flow processes to manage water resources in mountainous catchments. © 2025 Elsevier B.V., All rights reserved.