Considerations for Developing Effective Groundwater Recharge Policies

Derrik Williams gave this talk to Groundwater Association of California’s San Francisco Branch meeting June 17, 2013.

Mapping and quantifying natural groundwater recharge is arguably one of the most important factors in successful groundwater management. Unfortunately, recharge is often very difficult to measure directly. Recharge estimates are therefore often based on assumptions: some which are valid and some which are questionable. These assumptions can lead to, and have led to, land use policies that can be counterproductive to groundwater managers. A clear discussion of recharge mechanisms, physical factors limiting recharge, groundwater quality impacts from recharge, and ecological/habitat impacts from enhancing recharge must precede any land use decisions.

Because groundwater recharge is often viewed in the context of providing urban supplies, we will focus on recharge in urban areas – and land use policies that can enhance this recharge. This talk reviews the current understanding of the influences of urbanization on groundwater recharge from both a quantity and quality perspective. We will compare what is known about recharge with existing policies and recently passed legislation requiring mapping of recharge zones. Based on our understanding of recharge mechanisms, we can outline what hydrogeologists should consider when negotiating with land use planners, and how they should be influencing land use policy.

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