TITLE:
Calibration of HEC-RAS Model for One Dimensional Steady Flow Analysis—A Case of Senegal River Estuary Downstream Diama Dam
AUTHORS:
Raymond Diedhiou, Soussou Sambou, Seidou Kane, Issa Leye, Samo Diatta, Mousse Landing Sane, Didier Maria Ndione
KEYWORDS:
Diama Dam, Estuary, Flood, HEC-RAS, Senegal River
JOURNAL NAME:
Open Journal of Modern Hydrology,
Vol.10 No.3,
June
4,
2020
ABSTRACT: The Sahelian regions have experienced a drought that
has made them vulnerable to hydro-climatic conditions. Strategies have been
developed to reduce this vulnerability. The
governments of Senegal, Mauritania, Mali and Guinea have created the
Organization for the development of the Senegal River (OMVS in french) with the
aim of realizing large hydraulic installations. This resulted in the
construction of the Diama and Manantali dams in the Senegal River Basin. The
first aims to stop the saline intrusion, the second to regulate the flow of the
river, to allow the irrigation of agricultural perimeters, and to produce
electrical energy. The impoundment of the Diama dam has modified the hydraulic
behavior of the estuary. The purpose of this study is to carry out the hydraulic modeling of the estuary of Senegal
river downstream of the Diama Dam in transient mode by the HEC-RAS software.
Two geometric models were constructed on the basis of a digital terrain
model (DTM) using the Arc-GIS and HEC GeoRAS soft wares after processing the
collected topographic data. The first geometric model, of which the areas of
Senegal river downstream Diama Dam have been represented by cross-section, is
one-dimensional. The second one is also one
dimensional; in this model, the area of the Senegal River estuary
downstream Diama Dam is introduced as water storage zones. The components of
these models are the stream sections, lateral links, and storage areas. The
flood hydrograph downstream Diama Dam is introduced as conditions at the
upstream limits of the models while the tidal is introduced as a downstream
condition. After the stability and calibration, the results given by HEC-RAS simulations
are the variations of the water levels, the temporal variations of the flow
rates for each section, the maximum flow velocities and the propagation times
of the flood waves. The analysis and comparisons of these results strongly
suggest using HEC-RAS issues as a decision-making tool helping to manage floods
during times of crisis.