Flood control and land use management in Mengwa retention area, Huai River Basin†

Retention areas have a very important role in flood alleviation in the Huai River Basin. With economic and societal development the former retention areas have been developed and some of them even became very important urban areas. When floods come, there is a lot of damage. The government has realized that the flood control standards in the whole river basin are low and has made a plan to increase flood control standards for the Mengwa retention area. The design water level will be 28.00 m+MSL at Runheji. In light of this the use of the Mengwa retention area needs to be considered. To arrive at decisions that reduce flood damage, one should take into account the following uncertainties: the river discharge, the flood damage given the discharge, the downstream water level given the discharge, and the costs of constructing embankments and dredging the river. By using the DUFLOW model and a GIS model, the present situation and the alternative development options have been analysed. How to use the Mengwa retention area is also discussed. Copyright © 2004 John Wiley & Sons, Ltd. Les zones d'expansion jouent un role important dans la reduction des crues du fleuve Huia. Ces zones ont connu le meme developpement economique et social que le reste de la region, et certaines sont maintenant fortement urbanisees. Les crues y provoquent beaucoup de degâts. Le gouvernement a pris conscience que les criteres pour controler les crues dans le bassin versant sont insuffisants, et a elabore un plan pour ameliorer ce controle dans l'aire d'epandage de Mengwa. Le niveau d'eau de reference retenu est a la cote 28 m, prise a Runheji. Ceci implique de reconsiderer l'utilisation de la zone d'expansion. Les decisions permettant de reduire les degâts dus aux crues ont ete elaborees a partir des parametres suivants: debit du fleuve, relation entre le debit et les degâts dus aux crues, niveau d'eau en aval, couts de renforcement des digues, cout du dragage. La situation actuelle et les possibilites d'amelioration ont ete analysees avec le modele DUFLOW et un SIG. L'utilisation de la zone d'expansion de Mwenga est examinee egalement. Copyright © 2004 John Wiley & Sons, Ltd.