Combining a Physics-based Model and Spatial Interpolation of Scarce Bed Topography Data in Meandering Alluvial Rivers

Abstract

All human life is dependent on fresh water and activities related to monitoring its availability have become crucial for financial and survival reasons. Most rivers are being constantly investigated today by both the private and public sector using various means. In advanced countries, the researches cover extensively the riverbed in order to fully assess its topography. However, there are quite often cases where the data collected are disorderly scarce, resulting in questionable assumptions and interpolated predictions. The purpose of this thesis is to provide a new method for reconstructing the riverbed topography when data are scarce, so as to achieve better results than the ones conventional methods currently give. The chosen course of action involves a combination of the datasets outputted by a simplified physics-based model and spatial interpolation of the available scarce topography data. The surrounding research involves numerous aspects of mathematics, physics and spatial analysis, which together are called in to provide a complete solution to an existing problem. The focus lies on meandering alluvial rivers, whose planform style is the most common in human-populated river basin areas. Three rivers of different extent and interest are explored, namely the Danube (Romanian area), IJssel (Netherlands) and Kootenai (United States). The study cases comprise river areas extracted from each of them, in order to focus on bends and mildly widening or narrowing parts of the rivers. The final outcome of this Master Graduation Thesis project was achieved through literature research, exploration and implementation of ideas and scientific methods, made possible through cooperation with the Deltares independent institute for applied research. The proposed method combines scarce riverbed topography data with the basics of river morphology and spatial interpolation techniques to come to a new method that achieves a result of higher value in the complex field of river and geomatics engineering. The method is further assessed and evaluated and will ideally be incorporated in the Rapid Assessment Tool for Inland Navigation (RAT-IN) which is currently under development at Deltares.