STUDIES FOR INTAKE STRUCTURES OF FLOOD DETENTION BASINS TO BE ESTABLISHED ALONG THE UPPER RHINE

Abstract

The regulation of the Upper Rhine between the cities Basel and Mannheim, further its subsequent development for energy production by construction of 10 hydropower plants caused a significant diminution of the natural flood retention areas and consequently an enhancement of the flood peaks. In order to counterbalance this effect three types of measures are considered: 1. special operation mode of the power stations, 2. construction of flood retention weirs in the by-passed stretch of the Rhine, 3. establishment of flood-retention basins beyond the flood control dykes (levees). The author has been commissioned to elaborate design proposals for retention basins to be possibly erected in selected regions. Equations for calculation of the filling/emptying times are presented in the paper.. Besides, the headworks (inlet/outlet structures) of the basins have been tested under the guidance of the author in the Theodor-Rehbock Hydraulic Laboratory in order to obtain appropriate designs. The main requirements are: high discharging efficiency, reasonable openings as regards the movable gates, simple safety measures against scouring with respect to the two-direction flow, last but not least some aspects of environmental and landscape protection. The paper describes the results of the scale model tests and shows the design proposal. The discharge measurements in the model manifested a very good agreement with the equations.