SOIL MOISTURE DYNAMICS, GEOPROCESSING, AND HYDROLOGICAL MODELING AS SUPPORT FOR WATER SECURITY
Hydrological modeling; Water security; Peri-urban watersheds; Ecosystem services
Soil moisture regulates hydrological cycle processes, including infiltration, evapotranspiration, surface runoff, and groundwater recharge, constituting the central link between ecohydrological processes and water-related ecosystem services for water provision. In northeastern Brazil, this dynamic is particularly complex due to the seasonal rainfall regime, pedological heterogeneity, and increasing anthropogenic pressure on water resources. The Pitimbu River Watershed exemplifies this context: it encompasses Jiquí Lagoon, which is responsible for approximately 30% of the public water supply for the southern, eastern, and western zones of Natal, and has been subjected to intense urbanization processes, with direct consequences for regional water security. Despite its importance, the watershed lacks systematic hydrometeorological monitoring, limiting the calibration and validation of models. Given this scenario, this study investigates soil moisture dynamics in the Pitimbu River Watershed through an integrated approach that combines: a bibliometric review of the state of the science; assessment of the watershed’s environmental vulnerability; hydrometeorological monitoring; and distributed hydrological modeling, using soil moisture as the main variable for calibration and validation of hydrological fluxes. The bibliometric analysis on soil moisture revealed growth in Brazilian scientific production after 2010, with a concentration on agricultural drought studies and gaps in the integration of soil moisture and ecosystem service-oriented modeling. The environmental vulnerability of the watershed progressively increased between 1985 and 2024, with urbanized areas expanding by 138.7%, urban growth being one of the main drivers of the increase in vulnerability from High to Very High. Experimental monitoring showed distinct hydrological patterns among the studied soils: the Yellow Oxisol presented greater water retention and a dampened response to precipitation, whereas the Quartzipsamment showed rapid infiltration and high temporal variability in soil moisture, with direct implications for model parameterization. Upon completion of the modeling, the study is expected to accurately estimate hydrological fluxes and provide support for territorial planning and regional water management, with potential for replication in northeastern Brazilian watersheds with limited hydrological data availability.