Abstract

LUNA RAMOS, Lourdes  and  SOLE BENET, Albert. SOIL EROSION EXACERBATED BY A GRAVEL CUSHION ON A HILLSIDE UNDERGOING RESTORATION IN CANTERAS DE ALMERIA (SPAIN SITE). Rev.EIA.Esc.Ing.Antioq [online]. 2015, n.spe2, pp.13-19. ISSN 1794-1237.

One of the main soil degradation processes that occur in environments undergoing restoration is water erosion, to which mining hillsides are especially sensitive. The substrates used for restoration of these surfaces typically have a low infiltration capacity and high erodibility. Other factors can be combined with these conditions, including the presence of runoff contribution areas at the head of the restored hillsides, favoring the accumulation of runoff. Likewise, hillsides with steep slopes lead to surface flow acceleration, which can cause processes of erosion. In an experimental soil restoration design in 10 x 5 m parcels on limestone quarries implemented in March, 2012 in Almeria (SE of Spain), a gravel cushion (4-8 mm) between 5 and 10 cm thick was tested and compared with a non-cushion terrain along with the addition of organic amendment to the inert substrate and planting of native species. Cushions in semiarid Mediterranean environments mitigate soil temperature and evaporation, encourage infiltration, and reduce runoff and erosion. However, a single intense rain at the beginning of fall, 2012 (P = 40 mm; I₃₀ = 51.2 mm/h) caused a great deal of runoff on parcels with slopes between 15 and 30% and linear erosion of the cushion and the restoration substrate that reached an average of 0.224 m³ per parcel (63.5 t ha^-1) compared to half these values on non-cushioned parcels. This fact forces us to reconsider the benefits of gravel cushions as an anti-erosion measure on hillsides subject to torrential Mediterranean rains.

Keywords : Substrates; Soil Degradation; Linear Erosion; Restoration.

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