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Advisor(s)
Abstract(s)
Diffuse pollution from agricultural activities is a major environmental problem. The extent of the
impacts is driven, e.g., by local topography due to the influence on hydrological processes. This study aims to
investigate the use of different scale topographic data in assessing runoff-erosion processes. The TopAGNPS
module, a component of the AnnAGNPS model (Annualized Agriculture Nonpoint Source), was used to assess
the impact of the vertical resolution of the Digital Elevation Model (DEM) on the topographic and hydrological
configuration of a basin, and on the simulation of soil erosion. The study focuses on a small agro-forestry basin
(190 ha) located in the municipality of Idanha-a-Nova, Portugal. A georeferenced survey of the basin's surface drainage network was carried out and then compared with the results of the simulated drainage networks generated by the TopAGNPS module using two DEMs with vertical resolutions of 1m and 5m. The results show
that the DEM with a vertical resolution of 5m did not generate a reliable drainage network, given the relevant
differences between the modelled network and the field observations. On the other hand, the drainage network
generated with the DEM of 1m resolution was very similar to the observed drainage network. The use of
distinct topographic configurations modelled based on different vertical resolution DEMs on the estimation of
soil erosion by water using the RUSLE model (Revised Universal Soil Loss Equation), resulted in significant
differences considering the values of 5.85 and 4.17 ton/ha.year for the DEM with 1m and 5m vertical resolution, respectively. Considering that soil erosion by water and other processes, such as the transport of pollutants, are distributed processes, it is of great relevance to consider good topographic and hydrologic configurations to achieve more reliable simulations and better support decision-making.
Description
Keywords
Digital Elevation Model Data resolution AnnAGNPS model Soil erosion Agroforestry basin
Pedagogical Context
Citation
DUARTE, A.C. ; FERREIRA, C. ; VITALI, G. (2024) - Topography and hydrology modeling and influence on soil erosion simulation, at small basin scale. In the Mediterranean Geosciences Union Annual Meeting 2023 - Proceedings. SPRINGER (Artigo aceite para publicação).