Volume 3 nr 1 / 2011 - Academia Oamenilor de Stiinta din Romania

84 Lorand Catalin Stoenescu5. The calculation method for the propagation of the accidental flood waveThe propagation of the flood wave and the extension of the flooded areas weredetermined through a two-dimensional hydrodinamical calculation, withHYDRO_AS-2D computer program. The modeling of the discharge hydraulicconditions is based on the numeric solution of the bidimensional equation ofmedium water depth with Galerkin type volume elements. In this case, thedischarge speed is approximated with respect to the water depth. In order tosimulate such flow, a rectangular and triangular elements model was created,having a series of pre-established initial and boundary conditions. The calculationis controlled by the pre-established time step and by the total calculation duration.The general modeling and calculation procedure is presented here-under.5.1. Programs used for modeling and calculationsModel creation and flow calculation were realized with the help of two computerprograms:- Surface Water Modelling System (SMS) from BOSS International INC, USAand- HYDRO_AS-2D created by Dr. Nujic, Rosenheim, Germany.So, SMS is a pre- and post-processing program with which one can create anetwork of elements constitutes the digital terrain model and there are defined theboundary conditions, the control structures of the discharge (such as weirs andbridges) and control points of the discharge. With the help of SMS computerprogram, a linear unstructured network was modeled by using triangular andrectangular elements. This means that the model can be perfectly adjusted afterthe contour surface. The data regarding the relief, the inner part of the blowers ofthe bridges and the control points of the discharge are connected to the elements’knots and the roughness is attached to each element.5.2. Pre-processing (creation of the model)For the creation of the digital model of the land, topographical data were used tosum up approx. 10000 marking points, representing approx. 80 transverse sectionsand multiple points on a weight plan with a width of 200-800 m along the minorriver bed of the analyzed sector. The model was then created on the basis of thesemeasurements and on the basis of the photographs and information gathered onthe site visit. (fig. 10, 11 and 12).The standard values of the roughness’s from the minor and major river bed wereestablished on the basis of the information gathered during the site visit and of theexisting maps. The roughness from the major river bed were estimated on theCopyright © Editura Academiei Oamenilor de Știință din România, 2011Watermark Protected