Potential recharge to groundwater estimation, grid dataset, McBride Basalt Province

This grid dataset is an estimation of the relative surface potential for recharge within the McBride Basalt Province. This process combined numerous factors together as to highlight the areas likely to have higher potential for recharge to occur. Soil permeability and surface geology are the primary inputs. Vegetation and slope were excluded from consideration, as these were considered to add too much complexity. Furthermore, this model does not include rainfall intensity – although this is known to vary spatially through average rainfall grids, this model is a depiction of the ground ability for recharge to occur should a significant rainfall event occur in each location.The relative surface potential recharge presented is estimated through a combination of soil and geological factors, weighting regions that are considered likely to have greater potential for recharge (e.g. younger basalts, vent-proximal facies, and highly permeable soils). Near-surface permeability of soil layers has been considered as a quantified input to the ability for water to infiltrate soil strata. It was hypothesised that locations proximal to volcanic vents would be preferential recharge sites, due to deeply penetrative columnar jointing. This suggestion is based on observations in South Iceland, where fully-penetrating columnar joint sets are more prevalent in proximal facies compared to distal facies in South Iceland (Bergh & Sigvaldson 1991). To incorporate this concept, preferential recharge sites are assumed to be within the polygons of vent-proximal facies as derived from detailed geological mapping datasets.Remaining geology has been categorised to provide higher potential recharge through younger lava flows. As such, a ranking between geological units has been used to provide the variation in potential recharge estimates.ReferencesBergh, S. G., & Sigvaldason, G. E. (1991). Pleistocene mass-flow deposits of basaltic hyaloclastite on a shallow submarine shelf, South Iceland. Bulletin of Volcanology, 53(8), 597-611. doi:10.1007/bf00493688

本网格数据集为麦克布赖德玄武岩省（McBride Basalt Province）内地下水补给相对地表潜力的评估成果。
该评估整合多类因子以识别补给潜力较高的区域，其中土壤渗透率与地表地质为核心输入参数。考虑到植被与坡度会引入过多建模复杂性，故未将其纳入考量。
此外，本模型未纳入降雨强度因子：尽管平均降雨栅格数据已证实降雨强度存在空间异质性，但本模型旨在刻画当某区域发生强降雨事件时，地表实现补给的固有能力。
本次发布的相对地表补给潜力值，通过土壤与地质因子的组合运算得到，并对被认为具备更高补给潜力的区域赋予更高权重——例如年轻玄武岩、喷口近源相（vent-proximal facies）与高渗透率土壤。
土壤层的近地表渗透率被作为量化输入参数，用于表征水分渗入土壤地层的能力。研究提出假设：火山喷口附近区域因发育深度贯通的柱状节理（columnar jointing），可作为优先补给位点。
该假设基于南冰岛的观测结果：相较于远源相，南冰岛近源相区域更发育全贯通柱状节理组（Bergh & Sigvaldson, 1991）。为纳入该逻辑，本模型将优先补给位点限定为源自详细地质填图数据集的喷口近源相多边形区域。
其余地质类型则依据年轻熔岩流的补给潜力进行分级，借此通过地质单元间的优先级排序，生成差异化的补给潜力评估结果。

参考文献
Bergh, S. G., & Sigvaldson, G. E. (1991). 南冰岛浅海陆架上的玄武岩玻屑碎屑岩第四纪块体流沉积. 《火山学通报》, 53(8), 597-611. doi:10.1007/bf00493688