February 2012 Article (Early View): “Decentralized Groundwater Recharge Systems Using Roofwater and Stormwater Runoff,” by Daniel B. Stephens, Mark Miller, Stephanie J. Moore, Todd Umstot, and Deborah J. Salvato.
Conceptual Diagram of Water Balance Components for (a) an Undeveloped Site and (b) a Home Site With Low-Impact Development Technology.
This article assesses the importance of decentralized methods to reduce stormwater runoff, including methods such as low-impact development (LID) technology, and to enhance recharge in urban areas. For urban watersheds with net excess runoff, the authors examine the role for more widely distributed, artificial recharge systems at the home lot, subdivision, neighborhood, shopping mall, or business park scale, using captured roof or hardscape runoff to gradually replenish groundwater supplies without adding significant new large-scale infrastructure.
In this conceptual model of a decentralized urban recharge system, runoff is limited to the predevelopment condition. Thus, on a partially hardscaped lot, the water volume that could be salvaged from runoff would then be the precipitation minus the predevelopment runoff, minus natural recharge and evapotranspiration. Capturing runoff close to its source helps minimize dissolved chemicals or entrained sediment in runoff. By encouraging LID options that favor recharge, the benefits double; that is, groundwater storage increases and surface water quality improves.
Costs to implement decentralized systems seem to be favorable in comparison to centralized and heavily engineered systems, but, the authors note, there are few incentives currently in place to encourage public support; consequently, implementation is likely to be a slow process. Nevertheless, there is evidence that a movement toward decentralized systems may have already begun, as some municipalities, counties, states, and now likely federal facilities have begun to encourage or mandate groundwater recharge from stormwater at the local scale to a great extent.
[Please note: I have quoted and paraphrased freely from the article, but the interpretation is my own.]
