Assessment of water and sediment quality in intermittent streams across different land uses in the Brazilian semiarid region: implications for sustainable irrigation and resource management.

Abstract

Water scarcity is a critical global issue, especially in semiarid regions where limited water resources are increasingly pressured by socioeconomic vulnerabilities and agricultural demands. In this study, we evaluated the quality of water and sediment from intermittent streams in a watershed located in Brazil's semiarid northeastern region, assessing their suitability for irrigation while considering the influence of different land uses. Based on the Brazilian Environmental Council classification, we found that 82% of the sampled sites were categorized as freshwater, indicating general suitability for irrigation. However, the hydrochemical and sediment analyses revealed significant anthropogenic impacts, particularly at agricultural and urban sites, where higher levels of salinity, nutrients, heavy metals, and other pollutants were observed. Moderate salinization risks were noted at 70% of the sites, primarily linked to anthropogenic land-use practices, with total dissolved solids, chlorides, and bicarbonates emerging as key indicators of degradation. Riparian forests demonstrated a notable buffering effect, reducing salinity and nutrient levels, although elevated concentrations of manganese and iron were also detected, likely due to natural geochemical mobilization and upstream contamination. These results highlight the critical role of riparian vegetation in mitigating environmental impacts and emphasize the need for targeted soil and water management strategies, such as crop selection, irrigation practices, and land-use planning. By addressing the combined effects of land use and natural pressures on water quality, we provide essential insights for sustainable irrigation and resource management in semiarid regions, supporting both agricultural productivity and ecological preservation.