Id this weed
Hi - This is a type of smartweed (Persicaria sp.). We have several species of Persicaria in Maryland; some are native plants, some are not. https://www.marylandbiodiversity.com/viewChecklist.php?genus=Persicaria
Based on the flowers and leaf characteristics I can see in your photo, this looks like it might be the native Persicaria sagittata.
If you don't want it, you can pull it out before it disperses seeds.
More concerning is that there is Japanese stiltgrass in your photo as well. Japanese stiltgrass is an invasive species and a very aggressive spreader by seeds. It can be difficult to manage. It is an annual plant, so a key to its management is to remove it before seed dispersal. Seeds can persist in the soil for 5+ years. Here is more information about it and what you can do. https://extension.umd.edu/hgic/topics/japanese-stiltgrass
Any plants covering the ground, especially deep-rooted ones, will help to mitigate runoff, at least to some extent. We do often see other species of smartweeds growing alongside Japanese stiltgrass. They prefer a similar type of habitat.
If runoff and erosion are persistent problems for you, you might want to explore some of the options and resources on our stormwater management page. https://extension.umd.edu/hgic/topics/stormwater-management