A dry well is a good solution for temporary flooding problems that may leave large pools of water around a house or cause basement flooding. Dry wells allow water to flow away into a catch basin, where it is slowly absorbed back into the soil away from the home.
Ideally, precipitation runoff should flow away from a house, flowing down the natural gradient of the land to drains and gutters to be carried away. However, subsidence and other issues can affect the way surface water flows. A low spot in the yard collects water, creating a small, temporary puddle or pond. If the earth subsides near the house itself, water can pool against the foundation and seep through to cause water damage inside the basement.
A dry well involves digging a trench away from where the water naturally ponds to a deeper hole, where it falls into the basin and is reabsorbed into the earth. The drainage trench needs to be consistently angled downwards to prevent the water pooling elsewhere along the channel. The dry well itself needs to have a perforated bottom to allow water to flow away, and rocks and gravel in the trench and well keep the shape of the earth while not impeding the flow of water.