Soil erosion triggered by the archeological excavation and conservation of trenches. The case of “Cerro de las Trincheras” in Bailén (Jaén, Spain)

Abstract

Gully erosion is a landform developed due to accelerated soil erosion rates. Gullies can be identified by human impacts on geomorphological processes, as well as hydrological and erosional systems. In Spain, the trenches or "trincheras" from the Spanish Civil War (1936-1939) are considered of archaeological interest for several reasons. At Cerro de las Trincheras in Bailén (Jaén, Spain), a trench was built during the Spanish Civil War. In 2020, an archaeological excavation took place to restore the ruins, triggering the development of gullies and rills and a decrease in vegetation quality. We present a first approximation of the variations in vegetation cover and the decrease in quality (using NDVI, the normalized difference vegetation index) due to the trench acting as a gully (1956, 2005-2020) and the increase in rills and gullies after the excavation. We strongly advocate for future archaeological excavations to include a protocol (soil mapping, vegetation survey, and hydrological connectivity index) to reduce soil degradation and prevent damage to vegetation and associated ecosystems, thereby curbing the increase in soil erosion rates.