Impact of climate change on groundwater recharge in dry areas: An ecohydrology approach

Abstract

This work proposes an ecohydrology-based approach to study the impact of climate change on groundwater recharge in dry areas. It is largely based on a concept that in dry areas, vegetation community can be divided into two different groups, shallow- and deep-rooted vegetation, with the growing-season average of root-zone soil water saturation tending to be at its optimum value for the growth of deep-rooted vegetation. The concept is supported by data sets collected from different dry areas. Analytical results of soil water dynamics developed in previous studies are adapted here for investigating the impact of climate change. Because the conceptual model allows deep-zone soil–water saturation, averaged over growing seasons, to remain fixed during different climate conditions, we can construct a relationship among groundwater recharge, the coverage of deep-rooted vegetation, and climate. As an illustrative example, we apply the developed approach to the Yucca Mountain area. Our estimated recharge value under the current climate and the vegetation coverage is generally consistent with results estimated from other methods or observed from the site. We also evaluate how the recharge will change under several assumed future climate scenarios. The results show that both groundwater recharge and deep-rooted vegetation coverage increase with decreasing rainfall frequency (for a given amount of annual rainfall), with increasing average rainfall depth per rainfall event (for a fixed frequency) and with increasing frequency (for a fixed rainfall depth per rainfall event). The latter indicates a relatively large degree of buffering effects of vegetation on changes in groundwater recharge.