Title: Spatial and temporal variation of the soil moisture regime along a hillslope segment and a small mountain catchment

Authors: Daniel W. Woldie

Addresses: Environmental Consultant and Hydrologist, Addis Ababa, Ethiopia

Abstract: Relationship between spatial patterns of soil moisture pressure head, soil depth and topography is important to understand factors controlling the dynamics of infiltrated rainwater into the soil matrix. We analysed the spatial and temporal variability of soil moisture pressure head in a small catchment (0.2 ha) and along a heavily instrumented hillslope transect (25 m long) within a roaded catchment in the Fudoji experimental watershed, Shiga, Japan. We monitored these variations at different depths on 51 observation nodes on both sites. The pressure head measurements on the hillslope segment located within the roaded catchment revealed the importance of topography and geomorphic processes in dictating the propagation of the soil water pressure head. Geomorphic process strongly contributed to the variability in soil depth and soil vertical profiles of the upper, middle and lower parts of the hillslope segment. Similarly, results from systematically installed observation nodes on the small catchment shows a spatially organised soil moisture variation with depth in a relatively flat segment of the planar topographic unit. The changes in micro-topography and soil depth highly dictate the routing of infiltrated water to downslope sections and thus the amount of water stored in the soil profiles.

Keywords: tensiometers; saturated zones; hillslopes; topography; spatial variation; temporal variation; soil moisture; small catchments; mountain cachements; pressure head; soil depth; Japan; water storage.

DOI: 10.1504/IJHST.2016.075580

International Journal of Hydrology Science and Technology, 2016 Vol.6 No.2, pp.160 - 172

Received: 12 Mar 2015
Accepted: 26 Sep 2015

Published online: 28 Mar 2016 *

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