Experimental water drainage using selected Cenozoic deposits from the Sudetes and their Foreland

Stefan Kowalski


Presented are the results of hydrogeological investigations performed on samples of Cenozoic deposits from intermontane valleys of the Sudety Mts and from their foreland. Taken into account are hydrogeological parameters of the samples and also the conditions of water drainage. The report begins with an outline of geology and hydrogeology of the areas studied, accompanied by a detailed description of structural features shown by water-permeable sediments. The mineral composition of the sediments, their granulometric characteristics (grain size, roundness, sorting etc.) and the degree of consolidation of samples have been established. The total porosity and various kinds of bounded waters (especially adhesive and capillary waters) were next considered in connection with the above structural characteristics. Further, a differentiation in capillary water content in the processes of water-saturation and drainage has been shown. This differentiation was the greatest in samples of sediments from the intermontane valleys and the least in the sediments of the Mała Panew valley near Turawa Lake (Silesia Lowland). The content of bounded water, however, depends, first of all, on the grain size. It has been shown that even-grained samples of d10 grain--size exceeding 0.2 mm revealed similar adhesive water content and lack or low content of suspended capillary waters.
The above results became the starting point to achieve the principal objective of the work, that is to perform an analysis of drainage in conditions of different water saturation. For the complete saturation kinds and magnitudes of drainage perturbations have been established. It follows that the disturbances of homogeneity of the media in which the drainage takes place, is dependent on, among others, the ground air and mechanical suffosion. These relationships allowed an explanation of the existence of variations in pressure, in flow velocity and in value of water permeability coefficient, which change slightly following changes in the gradient of water table. Presented was also the role of water-permeability coefficient in the drainage process depending on particular structural features of sediment samples. Among others, a strict interdependence between the coefficients of drainage regression and of water-permeability was demonstrated.
It follows from the investigations that the main factor disturbing the values of parameters of drainage are conditions of undersaturation of the rock medium. It is mostly affected by drainage interrupting and temporal changes in the content of suspended capillary waters. The decrease of sediment consolidation results in a decrease of water-permeability, but in an increase of gravity storage coefficient. It follows from the present writer's work that the continuity of draining flow is conditioned by the degree of saturation exceeding approx. 0.7.
The results shown in several tens of diagrams and plots lead to conclusion that each draining flow depends on an association of structural features and on deformation of the medium during the water flow. Therefore its course should be considered separately for the conditions of saturation (filtration) and for the conditions of undersaturation (storage). The results of laboratory research was presented using a few examples of natural and artificial drainage in the field conditions.    


Experimental water sudetica

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