Geographic and Geometric Properties of the Watershed

All hydrologic analyses for TxDOT studies require collection of data about the geographic and geometric properties of the watershed. These data include, but are not limited to, the following:
  • Geographic location of the point at which design flow must be computed.
  • Location of the boundaries of the watershed from which runoff contributes to flow at the point of interest. This information will, for example, govern selection of design rainfall intensities that will be used with the
    rational method
    if that is selected for design flow computation.
  • Properties of the watershed within those boundaries. These properties include area, slope, shape, and topographic information. This information is needed, for example, to develop a model with which to simulate overland flow, as shown in
    Figure 4-10
    whereby water ponded on the surface moves across the watershed into channels.