The model optimization features were developed in the late 1990s. Technology in this area has advanced
significantly in recent years. The optimization trial is currently being completely rebuilt to take advantage of the
new advances. In particular, new methods will provide probabilistic parameter estimates in addition to the
traditional methods that are already available in the program.
The surface erosion methods currently available in the program provide results for whole subbasins, both
agricultural and urban. A new method is under development that will be physically-based by computing erosion
due to raindrop splash, sheet erosion, and rill erosion. The new method will allow for spatial variability in computed
erosion across each subbasin.
The Basin Map component of HEC-HMS is currently being modernized. The work will allow users to display new
data formats as background maps. The new Basin Map component will improve the display of subbasin, reach,
reservoir elements, and will also allow the easy importing of mapping data for the elements.
The Applications Guide is currently being updated. The current manual continues to provide good guidance for
using the software to conduct many different types of studies. However, the software now includes new features
that can make it easier and faster to perform some tasks. The chapter on reservoir spillway capacity studies will
be updated to show how to compute the probable maximum precipitation so that the probable maximum flood can be
computed at a reservoir. The chapter will also be enhanced to show improved methods for representing
spillway flow at reservoirs.
The current Technical Reference Manual was published in 2000 and was intended to describe Version 2. The
manual still accurately describes the features included in the software at that time. When time permits,
CEIWR-HEC will update the manual with new chapters about the many features that have been added to the
software since 2000.