Assessment of agri-spillways as a soil erosion protection measure in Mediterranean sloping vineyards

Suitable vineyard soils enhance soil stability and biodiversity which in turn protects roots against erosion and nutrient losses. There is a lack of information related to inexpensive and suitable methods and tools to protect the soil in Mediterranean sloping vineyards (>25° of slope inclination). In the vineyards of the Montes de Málaga (southern Spain), a sustainable land management practice that controls soil erosion is actually achieved by tilling rills in the down-slope direction to canalize water and sediments. Because of their design and use, we call them agri-spillways. In this research, we assessed two agri-spillways (between 10 m and 15 m length, and slopes between 25.8° and 35°) by performing runoff experiments under extreme conditions (a motor driven pump that discharged water flows up to 1.33 l s^-1 for 12 to 15 minutes: ≈1000 l). The final results showed: i) a great capacity by these rills to canalize large amounts of water and sediments; and, ii) higher water flow speeds (between 0.16 m s^-1 and 0.28 m s^-1) and sediment concentration rates (up to 1538.6 g l^-1) than typically found in other Mediterranean areas and land uses (such as badlands, rangelands or extensive crops of olives and almonds). The speed of water flow and the sediment concentration were much higher in the shorter and steeper rill. We concluded that agri-spillways, given correct planning and maintenance, can be a potential solution as an inexpensive method to protect the soil in sloping Mediterranean vineyards.