Estimation of overland flow metrics at semiarid condition: Patagonian Monte
Author:
Rossi M. J.,Ares J. O.
Abstract
Abstract. Water infiltration and overland flow (WIOF) processes are relevant in considering water partition among plant life forms, the sustainability of vegetation and the design of sustainable hydrological management. WIOF processes in arid and semiarid regions present regional characteristic trends imposed by the prevailing physical conditions of the upper soil as evolved under water-limited climate. A set of plot-scale field experiments at the semi-arid Patagonian Monte (Argentina) was performed in order to estimate infiltration-overland descriptive flow parameters. The micro-relief of undisturbed field plots at z-scale <1 mm was characterized through close-range stereo-photogrammetry and geo-statistical modelling. The overland flow areas produced by experimental runoff events were video-recorded and the runoff speed was measured with ortho-image processing software. Antecedent and post-inflow moisture were measured, and texture, bulk density and physical properties of the soil at the upper vadose zone were estimated. Field data were used to calibrate a physically-based, time explicit model of water balance in the upper soil and overland flows with a modified Green-Ampt (infiltration) and Chezy's (overland flow) algorithms. Modelling results satisfy validation criteria based on the observed overland flow areas, runoff-speed, water mass balance of the upper vadose zone, infiltration depth, slope along runoff-plume direction, and depression storage intensity. The experimental procedure presented supplies plot-scale estimates of overland flow and infiltration intensities at various intensities of water input which can be incorporated in larger-scale hydrological grid-models of arid regions. Findings were: (1) Overland flow velocities as well as infiltration-overland flow mass balances are consistently modelled by considering variable infiltration rates corresponding to depression storage and/or non-ponded areas. (2) The statistical relations presented allow the estimation of theoretical hydrodynamic parameters (Chezy's frictional C, average overland flow depth d*) through measurable characteristics of the surface soil and overland flow kinetics. (3) A protocol of field experiments and coupled time-distributed modelling to 1–2 above is described. The methodology and results obtained in this study are probably relevant to similar arid-semiarid areas of the world.
Publisher
Copernicus GmbH
Reference52 articles.
1. Abrahams, A. D., Parsons, A. J., and Luk, S.: Field experiments on the resistance to overland flow on desert hillslopes. Erosion, Transport and Deposition Processes, in: Proceedings of the Jerusalem Workshop, Jerusalem, March–April 1990, IAHS Publ. no. 189, 1990. 2. Aguiar, M. R. and Sala, O. E.: Patch structure, dynamics and implications for the functioning of arid ecosystems, Trends Ecol. Evol., 14, 273–277, 1999. 3. Antoine, M., Chalon, C., Darboux, F., Javaux, M., and Bielders, C.: Estimating changes in effective values of surface detention, depression storage and friction factor at the interril scale, using a cheap and fast method to mold the soil surface microtopography, Catena, 91, 10–20, 2011. 4. Ares, J. O., Beskow, M., Bertiller, M. B., Rostagno, C. M., Irisarri, M., Anchorena, J., Deffosé, G., and Merino, C.: Structural and dynamic characteristic of overgrazed grassland of Northern Patagonia, Argentina, in: Managed Grassland, edited by: Breymeyer, A., Elsevier Science, Amsterdam, 149–175, 1990. 5. Ares, J. O., del Valle, H. F., and Bisigato, A.: Detection of process-related changes in plant patterns at extended spatial scales during early dryland desertification, Global Change Biol., 9, 1643–1659, 2003.
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