Evaluation of hydrological and sediment connectivity in catchments with mining activity in semiarid central Mexico

Abstract

Source–sink systems in arid and semiarid regions contain low plant cover areas (inter-patches) functioning as sources of runoff, sediments, and nutrients that are retained by vegetated patches, which act as sinks. The spatial configuration of these hydrological units largely determines the connectivity network of runoff sources. At the same time, their dynamics are essential for assessing ecohydrological functionality, which mining can modify through the alteration of the system's ability to retain water and sediments, causing increased runoff and soil erosion. The objectives of this work were to: (1) identify the spatio-temporal changes in ground cover (i.e., vegetated patches and inter-patches) in two areas with mining activity: Cerro de San Pedro (1970–2015) and Villa de la Paz (1983–2014); and (2) evaluate, from an ecohydrological perspective, the changes in hydrological and sediment connectivity as the result of changes in ground cover in the two periods within each study area. Ground cover maps were obtained from aerial photographs and high-resolution WorldView 2 satellite images calibrated with 2 × 2 m plots measured in the field. For each study area, a transition matrix was used to assess spatio-temporal changes of patches and inter-patches, while hydrological and sediment connectivity were evaluated with the index of connectivity (IC). The results showed that the area with vegetated patches has decreased in Cerro de San Pedro and Villa de la Paz, leading to increased hydrological and sediment connectivity related to mining infrastructure and urbanization. The results can be used to prioritize areas for restoring ecohydrological functioning by reducing the connectivity of runoff sources.