Later these structures were built for various commercial purposes, but still without any scientific considerations and regulations. Finally they were built on the basis of scientific considerations and following certain regulations, but they served only relatively small interest groups. Until the nationalisation of the works they were built with simple local means of construction (by labourers using hand tools and wheelbarrows) and by relying on local funds (local associations). Recently they are built under government control by earth-moving machinery, subject to serious technical regulations and under supervision.
The contours and layers of earlier structures can still be identified in the levee cross-sections. These heterogeneous structures include organic materials and due to the pollution of surface waters several chemical processes were induced in them in addition to physical changes. This resulted in the ageing of the works and the deterioration of their protection potential.
Upon the effect of the changing hydraulic pressure caused by the flood waves the wetting of the body of the levees proceeds gradually from the water-side towards the protected side. In the simplest case this follows a linear seepage route. In the large levees steady seepage curves cannot be formed, not even upon the effect of long lasting and high flood waves. By comparing figures one can see that the wetting of the body of the levee proceeds even in the recession phase of the flood hydrograph.
The construction of the foundation of the levee is an extremely important technical task. The lower layers should be more carefully worked into the natural soil layer, than the higher ones with each other. Consequently the objective of having these works built up to a uniform level of flood-protection capacity is a hopeless and wrong one.
Flood defence activities should be urgently upgraded (training, organisation, technical development), since the expectations towards these activities became more sophisticated.
István Philipp C.E.
In: Vízügyi Közlemények
Vol. LXXXIII. Number 1/2002
All correspondence should be sent to:
VÍZÜGYI KÖZLEMÉNYEK
István Hegedüs
H-1453 Budapest, Pf. 27.
Information and Contacts:
Water Resources Research Centre - VITUKI
Prof. Dr. Lajos Szlávik
Kvassay Jeno út 1.
H-1095 Budapest
Telephone: +36 1 2156140
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