Water storage dynamics in a till hillslope: the foundation for modeling flows and turnover times
2017 (English)In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 31, no 1, p. 4-14Article in journal (Refereed) Published
Abstract [en]
Studies on hydrology, biogeochemistry, or mineral weathering often rely on assumptions about flow paths, water storage dynamics, and transit times. Testing these assumptions requires detailed hydrometric data that are usually unavailable at the catchment scale. Hillslope studies provide an alternative for obtaining a better understanding, but even on such well-defined and delimited scales, it is rare to have a comprehensive set of hydrometric observations from the water divide down to the stream that can constrain efforts to quantify water storage, movement, and turnover time. Here, we quantified water storage with daily resolution in a hillslope during the course of almost an entire year using hydrological measurements at the study site and an extended version of the vertical equilibrium model. We used an exponential function to simulate the relationship between hillslope discharge and water table; this was used to derive transmissivity profiles along the hillslope and map mean pore water velocities in the saturated zone. Based on the transmissivity profiles, the soil layer transmitting 99% of lateral flow to the stream had a depth that ranged from 8.9 m at the water divide to under 1 m closer to the stream. During the study period, the total storage of this layer varied from 1189 to 1485 mm, resulting in a turnover time of 2172 days. From the pore water velocities, we mapped the time it would take a water particle situated at any point of the saturated zone anywhere along the hillslope to exit as runoff. Our calculations point to the strengths as well as limitations of simple hydrometric data for inferring hydrological properties and water travel times in the subsurface.
Place, publisher, year, edition, pages
John Wiley and Sons Ltd , 2017. Vol. 31, no 1, p. 4-14
Keywords [en]
flow pathways, storage, storage dynamics, turnover time, Catchments, Digital storage, Dynamics, Energy storage, Exponential functions, Groundwater, Soils, Travel time, Water, Extended versions, Hillslope discharge, Hydrological properties, Mineral weathering, Vertical equilibriums, Rivers, discharge, flow modeling, hillslope, phreatic zone, porewater, runoff, water storage, water table
National Category
Oceanography, Hydrology and Water Resources
Identifiers
URN: urn:nbn:se:ri:diva-57260DOI: 10.1002/hyp.11046Scopus ID: 2-s2.0-85006246948OAI: oai:DiVA.org:ri-57260DiVA, id: diva2:1616170
2021-12-022021-12-022023-06-02Bibliographically approved