Wykorzystanie metod geoinformacyjnych w badaniach morfodynamiki koryta Wisły w Warszawie

Abstract

The use of geoinformation methods in Vistula channel morphodynamic research in Warsaw.A b s t r a c t. Prerequisite for rational river valleys management is estimation of its evolution processes causes and directions. Such analysis requires from geologist great number of different information, acquisition of which is very often associated with difficulties resulting (for instance) from channel zone inaccessibility. Besides accuracy in location of the observation points such works require also ability in registration of environment changes during short observation periods (e.g. on the base of subsequent measurement campaigns results) as well as during long periods (e.g. comparison of the topographic or remote sensing archival data ). The perfect tool for such purposes, which is capable to integrating variousresearch results are geographic information systems. In the regulated, downtown section of the Warsaw Vistula channel since the 60s of the last century to the early XXI century was recorded a steady decline in the level of the medium and low water flow. This process became a threat for the channel zone infrastructure. At the same time above and below this channel section, in the zone less equipped with the hydro-technical structures the process of aggradation was observed. This leads to increase of flood risk. The paper presents results of investigations, which were conducted in the Vistula River channel zone in Warsaw. During the research it was found that the reason for a particular channel environment behaviour in reaction on the management is the channel geology. In the narrow, regulated downtown channel section the contemporary alluvia substrate (built up with erosion resistant deposits) creates morphologically diverse protrusion. Upstream and downstream of that channel section the roof of alluvia substratum lowers. Lack of possibilities to deepening channel during the high waters passage in downtown narrowed channel reach affects the higher flow speeds and creates conditions of sediment transit . Shallow position of erosion resistant deposits floor affects also the thalweg course. Beyond the culmination of substratum Vistula represents the wild river, overloaded by alluvia.