A NEW DERIVATION OF HORIZONTAL TWO DIMENSIONAL DEPTH AVERAGED MOMENTUM EQUATION AND CONTINUITY EQUATION, WHICH INCLUDE TOTAL EFFECT OF POROSITY INSIDE THE VEGETATION

摘要

Porosity effects on the hydrodynamic equations are minimal in comparison with other resistance forceslike 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 imposeconsiderable effects on final outcomes. Horizontal two-dimensional depth averaged momentum andcontinuity equations were derived in first principles with porosity enhancement and it was noticed thatnew derivations showed considerable contrast with early practiced equations. Two-dimensional numericalsimulations were employed to show difference between the results of new and previous equations. It wasfound that, newly derived equations predicted maximum current velocity was higher than previousequations, maximum water depth was less than previous equations at mid and front of the forest, butmaximum water depth was higher than previous equations at behind the forest.