Microrelief-Controlled Overland Flow Generation: Laboratory and Field Experiments

G Padmanabhan,Xuefeng Chu,Daniel Bogart

doi:10.1155/2015/642952

G Padmanabhan, Xuefeng Chu + Show 1 more

Open Access

https://doi.org/10.1155/2015/642952

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Abstract

Surface microrelief affects overland flow generation and the related hydrologic processes. However, such influences vary depending on other factors such as rainfall characteristics, soil properties, and initial soil moisture conditions. Thus, in-depth research is needed to better understand and evaluate the combined effects of these factors on overland flow dynamics. The objective of this experimental study was to examine how surface microrelief, in conjunction with the factors of rainfall, soil, and initial moisture conditions, impacts overland flow generation and runoff processes in both laboratory and field settings. A series of overland flow experiments were conducted for rough and smooth surfaces that represented distinct microtopographic characteristics and the experimental data were analyzed and compared. Across different soil types and initial moisture conditions, both laboratory and field experiments demonstrated that a rough soil surface experienced a delayed initiation of runoff and featured a stepwise threshold flow pattern due to the microrelief-controlled puddle filling-spilling-merging dynamics. It was found from the field experiments that a smooth plot surface was more responsive to rainfall variations especially during an initial rainfall event. However, enhanced capability of overland flow generation and faster puddle connectivity of a rough field plot occurred during the subsequent rain events.

Highlights

Surface microrelief is one of the major factors that control overland flow generation, surface runoff, and other related processes
This study focused on examining overland flow generation under the influence of surface microrelief through a series of laboratory and field experiments
For the two finer soils, the smooth surfaces yielded more surface runoff. The hydrographs of their rough and smooth surfaces were characterized by a sharp increase almost immediately after runoff began at the outlets

Summary

Introduction

Surface microrelief is one of the major factors that control overland flow generation, surface runoff, and other related processes. During the P2P stage, excess rain water begins to fill depressions that eventually spill when the ponded water level reaches the maximum depression storage, which further triggers threshold flow, merging of puddles, and cascaded drainage towards the final outlet of the surface [1]. During this phase, contributing areas expand as hydrologic connectivity is strengthened. Surface microrelief influences runoff (its initiation, flow dynamics, and retention) indirectly through depression storage and surface ponding [9,10,11,12,13]

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