Nature-based solutions as a missing link in climate-resilient lowland hydrology: evidence from the Middle Banat drainage system

Lowland agricultural landscapes are increasingly exposed to climate-driven hydrological instability manifested through intensified rainfall extremes, prolonged droughts, rising temperatures, and altered groundwater–surface water interactions. In flat regions such as the Middle Banat drainage system in Serbia, hydrological functioning is controlled by slow system response, high groundwater sensitivity, and strong dependence on recipient water stages, making these landscapes particularly vulnerable to climate non-stationarity. Traditionally, flood protection and drainage in such systems have relied almost exclusively on grey infrastructure, while the regulatory role of Nature-based Solutions (NbS) within canal networks and drainage corridors has remained largely underestimated. In this study, long-term time series (2003-2023) of precipitation, groundwater levels, and recipient water stages were analyzed using a combined deterministic–stochastic hydrological framework, while future temperature and precipitation dynamics were projected using CMIP6 climate scenarios. Deterministic analysis was applied to interpret physical processes of infiltration, percolation, baseflow generation, and surface runoff propagation, while stochastic methods were used to detect trends, seasonality, system memory, and correlation structures under increasing climatic uncertainty. The results reveal persistent positive coupling between precipitation, groundwater levels, and recipient stages, confirming the storage-controlled behavior typical of flat lowland drainage systems. A statistically significant increase in mean air temperature and a strong rise in the number of extreme dry days were detected, while annual precipitation shows a slight long-term decline combined with pronounced intra-annual irregularity. Climate projections further indicate increased evapotranspiration demand, enhanced drought probability, and growing pressure on both natural groundwater recharge and conventional drainage capacity. Within this hydro-climatic context, NbS implemented directly along canals and within agricultural drainage corridors emerge as a critical missing link between scientific diagnostics and practical climate adaptation. Vegetated buffer strips and riparian strips along canals reduce flow velocity, enhance sediment and nutrient retention, promote bank stability, and improve thermal and ecological regulation of drained waters. Constructed wetlands and vegetated detention zones within the canal network increase temporary flood storage, attenuate peak flows, and enhance groundwater recharge under high-water conditions. Soil-focused NbS, including organic matter enhancement, cover crops, and micro-retention in fields, further strengthen infiltration capacity and drought buffering. The integration of deterministic–stochastic hydrological analysis with spatial NbS planning enables the identification of where, when, and at what scale such measures provide maximum hydro-climatic benefit within drainage systems. Beyond their engineering function, these NbS measures directly support SDG 13 by strengthening climate-change adaptation, reducing flood and drought risks, and increasing system resilience under non-stationary conditions, while simultaneously contributing to SDG 15 through the restoration of riparian habitats, enhancement of biodiversity corridors, improvement of soil functions, and reduction of diffuse agricultural pressures on aquatic ecosystems. The Middle Banat case demonstrates that climate-resilient lowland hydrology cannot rely solely on structural drainage control, but must embed NbS as functional components of canal networks, capable of simultaneously stabilizing groundwater regimes, mitigating hydrological extremes, restoring ecosystem services, and supporting integrated water, climate, and biodiversity policies. The presented framework provides a transferable scientific basis for bridging hydrological science, NbS practice, and sustainability-oriented policy implementation in large lowland agricultural regions facing climate-driven water instability.