ABSTRACT
DYNAMIC FLOOD CONTROL ALONG ARTERIAL DRAINAGE NETWORKS, A CASE STUDY Y. NEDELEC, D. ZIMMER, C. CHAUMONT and M.D. PORCHERON Cemagref, division ouvrages pour le drainage et 1'etancheite, Antony, France
Abstract Sub-surface drainage peak flow rates are in general smoothed at the plot scale because of an increase of local infiltration capacity and a reduction of surface runoff, whereas transfers are accelerated by the arterial drainage system, which is often over-designed due to the depth of the collector drains. This flow acceleration can be reduced by letting the network overflow in its less critical zones. This solution, which can result from adequate reduced cross sections such as crossovers for roads, is referred to as dynamic flood control. But very few methods are available to correctly define how to obtain these overflows and to afford maintenance problems. In order to describe the peakflow transfer through a small agricultural catchment, an hydraulic model based on St-Venant's equations was used, and applied to an experimental catchment near Paris (Orgeval, Seine-et-Marne), in which runoff comes essentially from subsurface drainage. The experiment and model results are used to build recommendations on dynamic flood control at a small catchment scale, by means of a correctly designed surface network, especially its reduced cross sections. These recommendations are now to be validated by multi-scale experiments, and design of effective equipment. Keywords: Arterial drainage, dynamic flood control, flood routing, modelling, peak flow, subsurface drainage
1 Introduction
Many floods occurred in France during the past five years, and agriculture intensification was accused by media and public opinion, of being largely at their origin. The development of agriculture may lead to a greater influence of human activities on
Water and the Environment: Innovative Issues in Irrigation and Drainage. Edited by Luis S.. Pereira and John W. Gowing. Published in 1998 by E & FN Spon. ISBN 0 419 23710 0
water regime, because of larger plots or specific hydraulic equipment, but responsibilities are not so easy to evaluate.
