Interactions of Microtopography, Slope and Infiltration Cause Complex Rainfall‐Runoff Behavior at the Hillslope Scale for Single Rainfall Events. Issue 7 (29th June 2021)

• Record Type: Journal Article
• Authors: Caviedes‐Voullième, Daniel; Ahmadinia, Ebrahim; Hinz, Christoph
• Is Part Of: Water resources research. Volume 57:Issue 7(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-29
• Subjects: microtopography -- surface roughness -- runoff‐infiltration partitioning -- runoff generation; Hydrology -- Periodicals; 333.91
• DOI: 10.1029/2020WR028127
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: Microtopography (MT) can govern runoff dynamics as a net result of local heterogeneities in the flow paths and ponding. This in turn controls the development of the surface water layer that connects and flows downslope. It is therefore important to understand which microtopographic features affect runoff generation dynamics and its macroscopic—hillslope scale—hydrological signatures (e.g., hydrographs, runoff and infiltration volumes). In this study, we numerically solve 2D overland flow from a single rain pulse on 1, 460 idealized hillslopes with different slopes and sinusoidal microtopographies and different infiltration capacities. We assess hydrodynamic distributions, hydrographs and hydrological indices to assess the effects of MT and infiltration on the (local) hydrodynamic and (larger scale) hydrologic responses in terms of surface runoff regimes. The results show that MT enhances infiltration and that infiltration and runoff depend in a strong non‐linear way on slope and the properties of MT. Three regimes of influence of MT were identified: one in which MT plays a negligible role but there is a high sensitivity to the infiltration capacity curve, a second regime in which hydrological partitioning is highly sensitive to MT and the infiltration capacity curve, and a third regime in which MT increases infiltration, but the response is insensitive to particular features, and more affected by the average slopes. The regimes are the product of the interplay between small (MT) and large scale (slope) properties. Furthermore, the results suggest that hydrological signatures can be interpreted and explained by the spatiotemporal variation of surface connectivity. Key Points: Microtopography plays a relevant role in rainfall‐runoff‐infiltration partitioning Different slopes and microtopographies result in a set of hydrodynamic regimes The hydrodynamic regimes can be related to hydrological regimes