Combining COSMO-SkyMed satellites data and numerical modeling for the dynamic management of artificial recharge basins

Many urbanized areas in the world are using artificial recharge basins (ARB) as an efficient solution to maintain adequate groundwater recharge while coping with flooding problems. The effective management of these basins to adequately maintain their functionality over mid-to-long term requires a suitable monitoring network. Here, we explored the use of a temporal satellite analysis to closely evaluate the efficiency of the ARB in terms of infiltration capacity, depending on hydraulic conditions of the topsoil transitioning from unclogged to clogged conditions in the ARB. COSMO-SkyMed synthetic aperture radar (SAR) images were integrated with ground data and numerical modeling to advance the capability for monitoring low water levels and flooded areas within the ARB. The understanding of biofilm development and effects was achieved by identifying anomalous drawdown phases, by constraining ponding boundary conditions in the numerical model, and by estimating subsequent infiltration rate changes under progressive clogging. With appropriate meteorological conditions (consecutive rainfall events separated by few dry days), the biofilm could develop rapidly and cover large surfaces (e.g., 22 ha) in about two months. During this process, the hydraulic conductivity of the basin surface could decrease by more than three orders of magnitude, completely altering the relationship with the local groundwater regime. Quantitative estimation of the evolution of the infiltration rate provides crucial insights about the overall recharge behavior of ARBs to make reliable economical plans in both the design and monitoring phase.