Groundwater Recharge in Old Cemeteries
I have a delightfully ghoulish topic of what happens to groundwater recharge in old cemeteries. As I have talked about before, groundwater recharge is important. First, the water table needs to be refreshed. Drawdowns reduce the water supply. Second, the ability of groundwater to absorb rainwater is important for reducing flooding. Old cemeteries pose interesting risks for groundwater infiltration. The first is that older cemeteries, especially those with without regular maintenance are unlikely to have good ground cover, with respect to greenery. This is a problem because grass, trees, and so on ensure better water infiltration and can also rerelease some water through transpiration. On the other hand, modern cemeteries are perfectly groomed and any pesticides will also infiltrate the groundwater. Another problem is that the graves themselves block infiltration. A grave is typically six-feet deep and inside a burial vault. The earliest burial vaults come from the middle 19th century and were introduced due to "coffin collapse." Basically, a coffin is not terribly rigid and eventually collapses under the weight of soil. The collapse leaves indentations in the grounds. The vault, made of brick, concrete, or some other rigid material reinforces the grave. Those material are pretty impermeable. It keeps the grave from contaminating the water table. But water moving through the upper soil layers are stopped, too. That water has to move around the burial vaults and means less rainfall is necessary to reach saturation. That slows the recharge rate, overall. It's basically the same as covering the surface with an equivalent sized impermeable surface. This is why you should get yourself turned into a tree. This helps in a lot of ways but protects the groundwater most of all.