Groundwater & Basement Water Intrusion in Des Moines, IA

Both, and specifically whether they are forecast to peak together. Each drains a different agricultural basin, so a storm centered over one can raise it while the other stays low, and the level at the confluence is far worse when the two coincide. Following both gauge forecasts rather than a single downstream number gives a much better picture, and the difference between coincident and staggered peaks is often the difference between a wet basement and a flooded floor.

On the bottomland the honest answer is no, and it is better designed around than resisted. Groundwater rises with the rivers during prolonged high stages and reaches basement floors from below regardless of the levees, so the space gets wet on a schedule set by weather rather than by anything an owner controls. Storage that tolerates wetting, equipment raised where possible, and no finished space at the lowest level turns a recurring loss into a recurring inconvenience.

Yes, and this city has a specific reason to. Municipal infrastructure sits in the same floodplain, and a major flood has previously interrupted water treatment for an extended period. That means a flood plan should include drinking water and sanitation independent of the house being dry. It is the kind of thing that seems excessive until the one time it happens.