Each, however, contributes important flood control, groundwater recharge, water treatment, and habitat to the Bay watershed. Hydrology and soils are particularly important to the way a wetland functions. This morning, Rolband showed us a mitigation bank under restoration near Quantico. He has planned the project with extreme care, studying groundwater levels at different seasons, the nature and permeability of soils, and computer-generated runoff models to figure out precise elevations and overall shape. Textural feel of soils is an important part of the process.
Hands still count.
The key is to be thorough, to get the soils and the hydrology just right. Heavy equipment operators must carefully sculpt the land according to the voluminous forty-page plan, even down to the tracks their bulldozer cleats leave. Those tracks provide microtopography, variations in elevation of a couple of inches that encourage a diverse community of wetland plants. Now as we walk the Haymarket wetland, Rolband frequently stops to study how plants are growing in a particular spot or tinker with tiny clay dams holding puddles of water. He clearly knows every square foot of this project and follows how water lies on it.