A digital elevation model (DEM) represents the topography of the earth's surface. An estimate of the elevation is generally available for each square meter. The “hydro-conditioning” process consists of modifying the DEM to reflect how water moves across the surface of the landscape (i.e., a hDEM).
For example, the DEM is modified to reflect how culverts and tile affect surface flows creating the hDEM. There are different levels of detail for hDEMs which reflect different business needs. The hDEM is a key input needed by the Prioritize, Target, and Measure Application (PTMApp) and affects how the products from PTMApp can be used.