Before you can even make out the green tops of palm trees, strange silhouettes on the sandstone eroded by the wind whisper of the existence of water in this scorching desert. These geological formations act as an incredible reservoir for water, which allowed the oasis to develop. This extremely precious resource was used for millennia thanks to wells dug to the underground reservoir of this massive aquifer system known as “Saq”. Based on hydrological, geochemical, and climatological data, the analysis of water resources by the WAO Project (Past, present and future Water resources in AlUla Oasis) makes it possible to evaluate its impact on the evolution of the landscape and agrarian practices, which in turn contributes to our ambition to create sustainable development in AlUla.