Mountain block recharge (MBR) mechanisms are an important component of the water budget for many alluvial aquifers worldwide. The MBR dynamics are complex, difficult to constrain, and quantification is highly uncertain. These challenges are magnified in data-scarce study areas, including the Cul-de-Sac and Leogane plains, two of Haiti’s largest alluvial aquifers, which are flanked by the Massif de la Selle mountain block. The associated groundwater supplies the regional metropolitan area of Port-au-Prince (RMPP) and it is facing increasing pressure, requiring improved understanding of the aquifer system to guide management and protection. This report introduces the aquifers and investigates the significance of river infiltration from flows originating from the mountain block. The approach to derive important insight on recharge included analysis of broad datasets on piezometry, isotopes, hydrochemistry, and streamflow. The findings indicate that river infiltration is a major source of recharge to the alluvial aquifers. Grise and Blanche river infiltration may account for >80% of recharge to the Cul-de-Sac aquifer, exhibiting temporal variation correlated to climate events such as cycles of the El Niño/La Niña Southern Oscillations. Momance and Rouyone river infiltration may account for >50% of recharge to the Leogane aquifer. The results direct attention to the Massif de la Selle carbonate aquifer system, where bulk recharge is estimated to be four times greater than both alluvial aquifers. The Massif not only supplies the RMPP with ~65% of its water supply from karst springs, but its streamflow also recharges the alluvial aquifers that supply the balance of RMPP supply.

山地补给 (MBR) 机制是全球许多冲积含水层水预算的重要组成部分。MBR 动力学是复杂的，难以约束，并且量化是高度不确定的。这些挑战在数据稀缺的研究区域被放大，包括 Cul-de-Sac 和 Leogane 平原，这是海地最大的两个冲积含水层，两侧是 Massif de la Selle 山脉。相关的地下水供应太子港 (RMPP) 的区域大都市地区，它面临着越来越大的压力，需要更好地了解含水层系统以指导管理和保护。本报告介绍了含水层，并研究了源自山区的河流入渗的重要性。获得关于补给的重要见解的方法包括分析测压法、同位素、水化学和水流的广泛数据集。研究结果表明，河流入渗是冲积含水层补给的主要来源。Grise 和 Blanche 河入渗可能占 Cul-de-Sac 含水层补给的 80% 以上，表现出与气候事件相关的时间变化，例如厄尔尼诺/拉尼娜南方涛动的周期。Momance 和 Rouyone 河流入渗可能占 Leogane 含水层补给量的 50% 以上。结果直接关注 Massif de la Selle 碳酸盐含水层系统，该系统的总补给量估计是两个冲积含水层的四倍。Massif 不仅为 RMPP 提供约 65% 的岩溶泉水供水，