Comparison of different flow direction methods for the preliminary estimation of saturated zones in the Luis Alves river basin – Santa Catarina, Brazil.
ISBN 978-85-88783-11-9
Authors
1Gerente, J.; 2Luiz, E.L.; 3Gomes, R.A.T.; 4de Oliveira, F.H.; 5Alves Dal Santo, M.
1UDESC Email: jessicagerente@gmail.com
2UDESC Email: elinluiz@uol.com.br
3UNB Email: robertogomes@unb.br
4UDESC Email: chicoliver@yahoo.com.br
5UDESC Email: m4rid4ls4nto@yahoo.com.br
Abstract
The formation of saturated zones in soils and regolith may trigger erosion dangerous processes such as mass movements. Topography characteristics exert great influence in convergence or divergence of surface and groundwater flows. From a digital elevation model (DEM) it is possible to extract important information about the potential of a given area for different erosion processes. The mathematical modeling enables to create different scenarios, in which the soil properties and external conditions may be calibrated. The O’Loughlin’s (1991) saturation model was used to recognize the most prone portions to saturation conditions at the Luis Alves River catchment – Santa Catarina, Brazil. It was also tested the response of three different flow direction methods used as input in the modeling: D8 (O’Callaghan & Mark, 1984), D-Infinite (TARBOTON, 1997) and the Multi directional flow (MDF) (Quinn et al, 1991). It was used a rain value of 250 mm/day (the same amount that triggered several landslides in this catchment in November 2008). Due the extension of this area, heterogeneity of material and depth of soil it were used three different values of transmissivity: 5 m²/day, 30 m²/day and 65 m²/day. Overlaying the results with a landslide inventory from 2008 it could be seen that considerable part of the landslides occurred in areas classified as susceptible to saturation. Since there are not steep slopes (steeper than 45º) in the catchment, the flow path in actual conditions tends to follow multiple directions. Therefore, the D-inf and MDF methods were the most suitable for a preliminary estimation of saturated zones in the study area. Systematic field investigations in order to calibrate and improve the validation of the model are suggested for future research.