Nature-Based Managed Aquifer Recharge solutions for mitigating water shortage at Danube-Tisza Interfluve, Hungary

Water shortage is a common challenge worldwide, and the Hungarian Great Plain is no exception. Climate change and human impacts (canal construction, afforestation, overpumping) have been causing severe water level declines in the area since the 1960’s. Water retention solutions are needed to preserve the natural vegetation and wet ecosystems and to ensure sustainable agriculture in the region. Water retention can be achieved in many ways, but consideration of the subsurface environment is inevitable. The Nature-Based MAR solution is based on the NaBa-MAR^© ELTE concept that integrates MAR methods and systematic groundwater flow for comprehensive landscape-scale water replenishment. In this way, not only is the storage capacity of aquifers considered, but the governing groundwater movement is also incorporated in the design of the water retention in an area. The naturally moving groundwater transports the retained water providing benefits locally and also further away. The main objective of introducing the concept^© is to match the demands and potentials in an area from a hydrogeological, social, and legal perspective. The applicability of the concept was assessed for the Danube-Tisza Interfluve area on a regional and local scale. As a first step, the available water sources were counted and the possibility of the infiltration MAR methods were investigated with MAR suitability mapping on a regional scale. Knowing this, the design of the possible MAR solutions was carried out on a local scale study area, taking into account the natural groundwater flow. Field measurements and numerical simulation helped to choose the most appropriate solution for rehabilitating a shallow lake environment. The results highlighted that local water retention solutions in regional recharge and through-flow areas have limited local effects. However, comprehensive NaBa-MAR solutions can have a landscape-scale impact in restoring the water level conditions in the area.

The work has been implemented by the National Multidisciplinary Laboratory for Climate Change (RRF-2.3.1-21-2022-00014) project within the framework of Hungary's National Recovery and Resilience Plan supported by the Recovery and Resilience Facility of the European Union. The work received funding from the European Commission and Ministry of Culture and Innovation of Hungary from National Research, Development and Innovation Fund; the Irish Enviromental Protection Agency; the Dutch Research Council and the Agencia Española de Investigación in the frame of the collaborative international consortium ClimEx-PE financed under the 2022 Joint call of the European Partnership 101060874 — Water4All. Project no. 2023-1.2.2-HE_PARTNERSÉG-2023-00005 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the 2023-1.2.2-HE_PARTNERSÉG funding scheme.