Effects of climate and land cover changes on water availability in a Brazilian Cerrado basin

The effects of riparian restoration and soil and water conservation practices on catchment hydrology are still unclear. Here, we assess whether a positive change in soil and water conservation practices and riparian reforestation will affect the water availability and boost resilience in a Brazilian Cerrado basin under climate change scenarios. This study was developed in the Três Marias basin (50.600 km²) located in southeastern Brazil. First, we calibrated (1992–2005) and evaluated (2006–2012) the Soil and Water Assessment Tool (SWAT) model. Then, we created a land cover and land use change (LCLUC) scenario that considers improving soil and water conservation practices and the reforestation of riparian zones, following the recommendations of the Brazilian Payment for Ecosystem Services (PES). We also used the trend SSP2-4.5 and the fossil-based economy SSP5-8.5 (Shared Socioeconomic Pathways) climate scenarios data from the Coupled Model Intercomparison Project Phase 6 (CMIP6) project for the period of 2015–2100. Along with a decrease of 5 %–15 % in precipitation in the projected period, an increase of 7 %–15 % in forest areas due to the LCLUC scenarios generated an increase in evapotranspiration values up to 38 %, resulting in a decrease of surface runoff and baseflow. Riparian reforestation and soil and water conservation practices did not necessarily enhance water availability on the simulations performed, as expected by many PES. © 2021 The Author(s)Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Significant baseflow reduction in the sao francisco river basin

Water scarcity is a key challenge to global development. In Brazil, the Sao Francisco River Basin (SFB) has experienced water scarcity problems because of decreasing streamflow and increasing demands from multiple sectors. However, the drivers of decreased streamflow, particularly the potential role of the surface-groundwater interaction, have not yet been investigated. Here, we assess long-term trends in the streamflow and baseflow of the SFB during 1980–2015 and constrain the most likely drivers of observed decreases through a trend analysis of precipitation (P), evapotranspiration (ET), and terrestrial water storage change (TWS). We found that, on average, over 86% of the observed decrease in streamflow can be attributed to a significant decreasing baseflow trend along the SFR, with a spatial agreement between the decreased baseflow, increased ET, and irrigated agricultural land in the Middle SFB. We also noted a decreasing trend in TWS across the SFB exceeding –20 mm year−1 . Overall, our findings indicate that decreasing groundwater contributions (i.e., baseflow) are providing the observed reduction in the total SFR flow. A lack of significant P trends and the strong TWS depletion indicate that a P variability only has likely not caused the observed baseflow reduction, in mainly the Middle and Sub-middle SFB. Therefore, groundwater and surface withdrawals may likely be a driver of baseflow reduction in some regions of the SFB. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]