A coupled mechanistic and in situ data approach to quantify the water retention potential of Nature-Based Solutions

EGU NH1.7

A coupled mechanistic and in situ data approach to quantify the water retention potential of Nature-Based Solutions

 

The increasing frequency and intensity of droughts poses great challenges to water availability and the functioning of natural ecosystems. In response to this, nature-based solutions (NbS) have emerged as a promising alternative to traditional infrastructure. NbS offer multiple benefits, including water retention, improved water quality, biodiversity conservation, and carbon sequestration. However, despite the growing recognition of their potential, the hydrological benefits of NbS remain poorly understood. The hydrological effects of NbS, such as water retention and groundwater recharge, are complex and require an integrated understanding of surface and groundwater interactions. However, current models for assessing water retention benefits are either too complex or not specialized to capture the unique features of NbS interventions. As such, the hydrological benefits associated with NbS are not fully understood. Furthermore, long-term in situ data that provides evidence of the benefits of NbS is also lacking. Consequently, the adoption of NbS remains limited due to the lack of clear evidence regarding their effectiveness in mitigating water scarcity.

 

In our study, we address these gaps by developing a simplified hydrological model designed to quantify water retention benefits of reclaimed and rewetted areas in a nature conservation area. The model is based on physically-based hydrological properties, which allow it to represent the fundamental water retention mechanisms of NbS. The model captures the interaction between the catchment area, the water retention zone (the NbS intervention), and the exchange between surface and groundwater. To validate the model and provide robust evidence, we complement the modelling approach with in situ data collected from a network of low-cost soil moisture sensors and groundwater piezometers. The deployment of these sensors allows for extensive monitoring at a relatively low cost, which is crucial for obtaining long-term data on the performance of NbS.

Our study demonstrates that NbS have the potential to mitigate water scarcity by enhancing both surface and groundwater storage, and the findings provide evidence that NbS can contribute to drought adaptation, with the added benefit of providing other ecosystem services. We also conclude that this coupled approach could serve as a useful tool for promoting the wider adoption of NbS in water resource management strategies as a multi-benefit alternative or companion to traditional infrastructure-based solutions.