Hydraulic model to assess the hydromorphological changes within the Danube Delta

Abstract

Morphological changes of the hydrographic networks (rivers /channels /brooks /lakes) as result of fluvial processes (erosion and alluvial sedimentation) induce modification on hydrologic regime with positive /negative impacts on biodiversity. This paper aims at emphasizing the amplitude of these processes within the Danube Delta Biosphere Reserve (Romanian part) inner hydrographic network, by means of the morphologic model, as maincomponent of 3D mathematical /hydraulic model. It is constructed based on geo-referenced database as resulted from hydraulicand bathymetric field measurements carried out within 2008-2010. Hydro-morphological changes are assessed by analyzingthose zones where fluvial processes have been identified to be active, meaning that specific hydraulic conditions are fulfilled,such as: water flow with high energy /high values of hydraulic parameters: level, speed, slope, and solid transport (upstream ofdelta: erosion) followed by a decrease of these values (middle part: alluvia sedimentation) and ending with very clear water at very low flow velocity (downstream of delta: no fluvial processes). Both erosion and, especially, alluvial sedimentation zones, in low water level conditions lead to disconnection of some channels /lakes generating ecological disequilibrium with negative impact on some flora and fauna species. Thus, the gained knowledge on the aquatic ecosystem function is used as scientific tool for decision making on a sound management of such an environment system in order to improve the quality of aquatic life by restoration of hydrographical network with impacts on habitats and overall ecological reconstruction.

Keywords

• fluvial processes amplitude
• hydraulic conditions
• hydromorphological changes
• 3D hydraulic model