Hydromorphological conditions of the lower Vistula in the development of navigation and hydropower

Abstract

The article presents general principles of development of the lower Vistula channel in the Holocene period, with a particular emphasis on the unintentional human interference in the fluvial processes associated with deforestation and cultivation of cereals and root crops. It also characterises the basic hydraulic engineering works in the form of construction of embankments, adjustment of the bed and construction of the Wloclawek barrage as factors of deliberate human interference and their impact on channel changes. The article characterises morphological and morphodynamic conditions of the basic bed forms, i.e. sandy and gravel bars and pools determining the possibility of river transport, and its development in time and space (depth of navigable route). Perspectives of multi-directional hydraulic development are presented, including the main cascade developments of the lower Vistula. The article presents the opportunities for a comprehensive use of the waterway, which forms route E40 in the section of the lower Vistula, taking into account sustainable development and compensation in the form of restoration of the valley bottom. DOI: 10.12736/issn.2300-3022.2013206 Introduction The use of river waters for economic purposes is dependent on the hydromorphological features of their channels, shaped by the climate and human activity. The climate affects the fluvial processes by precipitation (water regime) and air temperature (growth of vegetation in the basin and ice phenomena), phenomena independent of humans. Human activity can have a direct and indirect impact on changes in river channels. The first case concerns a change in the structure of forests for agricultural fields; such works accelerate the natural water flow (runoff) and increase the supply of load to channels. In the second case we are dealing with deliberate water management, aimed at control of the water regime by all kinds of hydraulic structures, including embankments, adjustment of channels or dams. An additional factor affecting the development of inland navigation is the change in technical conditions of vessels, e.g. an increase in draft of river boats associated with the transition to motor power. However, the river water regime and the transport volume of bed load have a leading role in the conditions of development of water transport and hydropower; those phenomena shape the channel patterns with the system of bed mesoforms of positive sandbars and the opposing negative forms, pools. They determine the parameters of waterways (width and depth of water routes), durability and functionality of hydraulic structures, including hydropower (reservoir filling time). The purpose of this article is to present the main stages and general trends in the development of the bottom of the lower Vistula (dolna Wisla) valley on the section from the mouth of the Narew to the mouth of the Vistula (dolna Wisla) to the Baltic Sea (Fig. 1), with particular emphasis on the influence of human economic activity. This applies mainly to changes in the spatial arrangement of the river channel, as well as to vertical movements of the bottom associated with the process of erosion and deposition of clastic load, mainly bed load. The main purpose is to define the dynamics of bed mesoforms like sandbars and pools, with an indication of possible directions of adaptation in terms of development of international waterway E40, improvement for ferry and road passages, construction of dams, improvement (elimination) of flood conditions while maintaining sustainable development (environmental protection). Furthermore, the article is to present the possible full utilisation of water in the lower Vistula (dolna Wisla) for economic purposes, including revitalization of the valley floor. The study has been prepared on the basis of the literature and own research in the field of hydromorphological changes occurring in the lower Vistula (dolna Wisla) channel. The analysis Z. Babinski, M. Habel | Acta Energetica 2/15 (2013) | 83–90