Assessing the Effects of Miedzyodrze Area Revitalization on Estuarine Flows in the Odra River

Abstract

The estuarine section of the Odra River network is influenced by various phenomena that shape its hydrological regime. The Lower Odra region includes “Miedzyodrze,” an area between the main branches of the Odra River that was previously used for agriculture. However, due to a lack of maintenance in the 20th century, Miedzyodrze’s infrastructure suffered significant damage, resulting in blockages and channel shallowing. Previous models of the lower Odra River network overlooked Miedzyodrze’s hydrodynamic impact on flow. To address this, a study aimed to assess Miedzyodrze’s influence on flows within the network. Three computational scenarios were developed: one treating Miedzyodrze as an uncontrolled floodplain, another excluding it from the flow like past models, and a third incorporating the hydraulic capacity of selected Miedzyodrze channels with hypothetical restoration. The construction of the models involved extensive field research, including bathymetric surveys and an inventory of channels and structures. Challenges arose from legal and technical constraints during the research. The hydraulic network model was developed using Hec-Ras software and underwent calibration and verification processes for accuracy and reliability. The study focused on analyzing changes in water distribution, flow reduction along the East Odra, flow ratios at specific points, and downstream flow alterations based on different scenarios and the aperture extent of the Widuchowa weir. The conducted analyses and deductions validate the thesis proposed in this study that the potential process of channel dredging and renovation of the hydraulic infrastructure in Miedzyodrze will significantly influence the flow distribution within the lower Odra River network. The significant impact of the Międzyodrze area on water distribution in the lower course of the Odra River has been successfully demonstrated. Under specific hydrological scenarios, a potential increase in flow through the Międzyodrze area from approximately 10–100 m3/s to a range of 60–420 m3/s has been identified. This dynamic alteration of river flow exerts a pronounced influence on further water distribution within the entire river network. For the purpose of addressing the matter at hand within this study, the following procedures were undertaken: → analysis of characteristic flow regimes and states, → bathymetric measurements, → flow measurements at selected cross-sections, → construction of a numerical model of the river network, → model calibration, → formulation of a set of boundary conditions, → modeling, → results analysis.