资源环境科技发展态势分析平台

Microtopography 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 work, we numerically solve 2D overland flow from a single rain pulse on 1460 idealised hillslopes with different slopes and sinusoidal microtopographies and different infiltration capacities. We assess hydrodynamic distributions, hydrographs and hydrological indices to assess the effects of microtopography and infiltration on the (local) hydrodynamic and (larger scale) hydrologic responses in terms of surface runoff regimes. The results show that microtopography enhances infiltration and that infiltration and runoff depend in a strong non-linear way on slope and the properties of microtopography. Three regimes of influence of microtopography were identified: one in which microtopography 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 microtopography and the infiltration capacity curve, and a third regime in which microtopography 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 (microtopography) and large scale (slope) properties. Furthermore, the results suggest that hydrological signatures can be interpreted and explained by the spatiotemporal variation of surface connectivity.

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