R--HEC-RAS 2D Only Mode and New 2D Boundary Conditions

This contract action was accomplished using other than competitive procedures because there is only one responsible source as this is a follow-on contract, and no other supplies or services will satisfy agency requirements (FAR 6.302-1). See posted J&A for further information. Two Dimensional (2D) modeling capabilities have been recently added to HEC-RAS and the enhancements contained in this PWS are necessary to improve the new 2D capabilities prior to public release of HEC-RAS version 5.0. This sole source contract includes a task to add a new boundary condition type to the 2D code. Currently, water can only move between a 2D area and a 1D river reach through a lateral structure. An additional boundary condition type, added through this contract, will allow water to move between the river and 2D areas. This sole source contract includes tasks to improve the computational speed of the 2D engine. These tasks include the solution of 2D flow only in cells with water, explore how the FORTRAN code is compiled in order to gain shorter simulation times, and enhance the computation of water flowing between storage areas. Another task included in this contract will add the ability to solve the 2D equation solver by itself without requiring a 1D river reach in the model. Finally, this contract contains a task to update technical documentation describing the 2D code within HEC-RAS.