Arid and semi-arid regions constitute an area where approximately 20% of the global population lives and the groundwater represents the only source of fresh water supply in many cases. In Extra-Andean Patagonia, located in the south extreme of South America, the landscape dominated by basaltic plateaus is associated with wet meadows, which are the only source of fresh water for rural inhabitants in a region characterized by arid conditions. The aim of this work was to define the geological and geomorphological controls that condition the formation of wet meadows associated with basaltic plateaus in a sector of the Extra-Andean Patagonian. For this, fieldworks were carried out that included geological profiles, rock sampling and geomorphological description of the sectors associated with wet meadows. The perennial character of wet meadows is supported by lithostratigraphic, structural and geomorphological controls that regulate the recharge, storage, flows and discharge of the groundwater that sustains them. The subhorizontal position of the basaltic plateau and the presence of fractures allow the rapid infiltration of rainwater that recharges the aquifers. The lithology, structure and paleorelief of the underlying rocks to the basalts determine the storage and flow of groundwater. Despite the great extension of the basalt plateaus and their homogeneity, there are different geological-geomorphological combinations in the underlying rocks that give rise to a great variety of controls of the water flows that sustain the wet meadows. The data obtained provide new information for the knowledge of wetlands and water resources in arid environments such as Extra-Andean Patagonia, where wet meadows provide water supply of local people, livestock and vegetation, constituting a relevant ecosystem service.

干旱和半干旱地区构成了大约 20% 的全球人口居住的地区，在许多情况下，地下水是淡水供应的唯一来源。在位于南美洲最南端的安第斯巴塔哥尼亚外，以玄武岩高原为主的景观与潮湿的草地有关，这是干旱地区农村居民唯一的淡水来源。这项工作的目的是确定地质和地貌控制条件，这些控制条件影响了与外安第斯巴塔哥尼亚地区玄武质高原相关的湿草甸的形成。为此，开展了实地工作，包括与湿草地相关的部门的地质剖面、岩石取样和地貌描述。湿草甸的多年生特征得到了岩石地层学、结构和地貌控制的支持，这些控制调节了维持它们的地下水的补给、储存、流动和排放。玄武质高原的亚水平位置和裂缝的存在允许雨水快速渗透，为含水层补给。下伏岩石对玄武岩的岩性、结构和古地貌决定了地下水的储存和流动。尽管玄武岩高原有很大的延伸和它们的均质性，但在下伏岩石中存在不同的地质地貌组合，从而对维持潮湿草甸的水流进行了多种控制。