Abstract
Porosity effects on the hydrodynamic equations are minimal in comparison with other resistance forces like drag and inertia that generated by water flow through vegetation in case of sparsely grown forests. However, in case of densely grown vegetation that have lowest porosity (high blockage) can impose considerable effects on final outcomes. Horizontal two-dimensional depth averaged momentum and continuity equations were derived in first principles with porosity enhancement and it was noticed that new derivations showed considerable contrast with early practiced equations. Two-dimensional numerical simulations were employed to show difference between the results of new and previous equations. It was found that, newly derived equations predicted maximum current velocity was higher than previous equations, maximum water depth was less than previous equations at mid and front of the forest, but maximum water depth was higher than previous equations at behind the forest.
