Re: O'Geen et al., “Soil suitability index identifies potential areas for groundwater banking on agricultural lands,” California Agriculture 69:75–84:

I believe we should also consider old approaches that at the time weren't considered aquifer recharge, but water wasted to the ground. Being raised in the Central Valley, I remember many a hot day spent swimming in cool canals carved into the soil. Then I observed the conversion of nearly all dirt-lined canals to concrete-lined canals, mostly in the name of water conservation. While probably reducing maintenance needs, this also eliminated miles (and acres) of recharge surfaces. If we could return lined canals back to earthen canals, this “old” approach could expand recharge across many portions of the state crisscrossed with canal systems. Furthermore, if the purpose of canal management could be expanded from water delivery conveyances to include water storage (i.e., kept watered year-round except during periods of maintenance), there might be enough water stored in them to obviate the need for new a reservoir or two.

Brad Valentine, Santa Rosa

April–June 2015

I found the concept behind the article — artificial infiltration and accelerated recharge — fascinating.

Resource management looks at stormwater as an economic resource. In the climate upheavals to come, the predictions are for sudden, massive storms that shorten the infiltration intervals. The kind of flood infiltration talked about in the article tends to this direction.

I think we do need to design farms for recharge rather than drainage. Sustainable design aims at preserving the structure and function of the natural water cycle, including groundwater recharge, despite an unstable climate. Ecology tends to look at the structure and function of the natural world, and how best to preserve natural cycles is a high priority of sustainability. But this is a difficult, if not impossible, task that challenges the best of us. We need to know the natural recharge capacity of the land, and derive a realistic threshold value for recharge — what nature would do had the land remained wild and unconverted to farmland. “Ecological farming” strains my imagination, because I am not an ecologist — but I wonder if we couldn't model natural thresholds in the same manner as this article models artificial recharge.

Bud Hoekstra, Glencoe