Catchment scale analysis of the effect of topography, tillage direction and unpaved roads on ephemeral gully incision

Abstract

High-resolution airphotographs and digital elevation models (DEMs) were used to study areas prone to gully incision in a small agricultural catchment in northern Israel. Data are analyzed to understand better the integrated effect of environmental and human factors on gully incision. The effect of fl ow accumulation, slope, unpaved roads density and tillage direction on gully width and length is found discontinuous and topography -in the form of the topographic threshold -was found to be the most dominant factor on gully incision in the catchment scale. The topographic threshold coeffi cients observed in Yehezkel catchment were lower than those found in previous studies, due to the effect of large rainfall events during the early winter season, when the soil in fi elds is still unprotected by crops. In addition, a survey of previous studies shows that, in cultivated areas, there is relationship between the topographic threshold coeffi cients a (multiplier) and b (exponent). The infl uence of unpaved roads and tillage direction on gully incision was also found signifi cant and consistent during the two seasons observed, while the nonparametric test showed that it added to the prediction in ~15% of the gullies. Incision points density plot show that of the two parameters, the unpaved roads were found to have greater infl uence on gully-head location than tillage direction. Studying the phenomenon on the catchment scale allows better understanding of the effect of spatial variation on gully-head location. Copyright

Scale effects on the estimation of erosion thresholds through a distributed and physically-based hydrological model

“…The relationship between the local slope of a gully or a channel head, S, and the drainage area, A, has often been used for the identification of erosion thresholds Dietrich, 1988, 1994;Willgoose et al, 1991;Tarboton et al, 1992;Prosser and Abernethy, 1996;Schoorl et al, 2000;Vandekerckhove et al, 2000;Hancock and Evans, 2006a;Svoray and Markovitch, 2009), mainly due to its potential for describing surface morphology and ability to integrate the major geological, climatic and vegetation-cover features of a basin (Hancock, 2005). This relation can be represented by the power function (Vandaele et al, 1996) …”

Gully erosion susceptibility assessment by means of GIS-based logistic regression: A case of Sicily (Italy)

“…In the Mediterranean landscape, expansion of pastures is often reported as one of the main drivers of gully erosion (Zucca et al, 2006;Gómez Gutiérrez et al, 2009b). The latter can also be enhanced by roads that intercept and concentrate overland flow, draining it on downstream slopes (Jungerius et al, 2002;Nyssen et al, 2002;Takken et al, 2008;Svoray and Markovitch, 2009).…”

The origin and control of mega-gullies in Kinshasa (D.R. Congo)

“…This has been recently shown in SW-Nigeria (Adediji et al, 2013) and in China (Sun and Wang, 2013). In many instances, researchers have focused on the role of paved as well as earth roads in producing and concentrating runoff and hence in reorganizing the natural drainage in Europe (Boardman, 2013;Waldykowski and Krzemien, 2013), in SE-Australia (Munoz-Robles et al, 2010), in northern Israel (Svoray and Markovitch, 2009) and in Kenya (Jungerius et al, 2002). We prefer the term of 'axial' gully instead of 'road'-gully, because in Kinshasa gully development is observed not only upon roads, but upon all structures which produce and/or concentrate runoff, including sewers.…”