Impacts of agriculture in the largest irrigated perimeter region from Latin America: effects on land degradation in the Samambaia River Basin

Abstract

The increasing demand for water resources has resulted in environmental degradation and conflicting interests among diverse users. This research aimed to scrutinize the causes and repercussions of land use exploitation and degradation within the Samambaia River Basin (SRB), focusing on potential environmental impacts linked to the management of irrigated agriculture. The study encompassed the entire SRB. Adopting climatological data from 1981 to 2010, distinct dry and wet seasons in the SRB were delineated. A precise slope map has been produced based on an elevation dataset, while vegetation indices like the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) have been computed. Indices such as the Woody Vegetation Biomass Index (WVBI), Vegetation Vulnerability Index (VVI), and Land Vulnerability Index (LVI) were derived from the NDVI. The dataset underwent descriptive statistical analysis, incorporating adjustment and validation factors. The root mean square error (RMSE) values for the daily rainfall data were notably low (7.0711 and 7.9223 mm). The years 2015, 2016, and 2018 experienced heightened rainfall during the dry season, while 2015 and 2018 recorded significant rainfall in the wet season. NDWI ranged from − 0.41 to 0.24, with positive values indicating the presence of water bodies in the SRB. During the dry season, regions with denser vegetation are largely associated to areas with central pivot irrigation. The WVBI revealed intensified vegetation in the wet seasons of 2014 and 2019. The LVI during the dry season varied from moderate to very low, with limited high-risk areas predominantly along water body boundaries.