1. Basinwide flood control/waffle project

AN INNOVATIVE APPROACH TO BASINWIDE FLOOD CONTROL: THE EVALUATION OF THE W AFFLE@ CONCEPT EXECUTIVE SUMMARY The following summary describes a multiyear study to evaluate the feasibility of employing a basinwide, distributed, temporary storage strategy as a means of augmenting existing dikes and controlling the devastating effects of springtime flooding in the Red River ofthe North Basin (RRB). With funding provided by the U.S. Department of Agriculture Natural Resources Conservation Service (NRCS) and input and guidance from two advisory boards, the Energy & Environmental Research Center (EERC) evaluated the feasibility of utilizing a basinwide system for temporary storage of floodwater in the RRB. The flood mitigation approach, referred to as the Waffle concept, could be accomplished by temporary storage of springtime runoff in existing "depressions" within the basin, primarily ditches and low-relief fields bounded by existing roads. The storage areas, roads, and existing drainage systems could act as a distributed network of channels and control structures for the temporary storage and controlled release of the retained water to reduce peak flood crests along the Red River and its tributaries. In order to evaluate the efficacy of the Waffle concept, it was necessary to 1) determine if sufficient storage capacity is present in the RRB to provide significant mitigation of major springtime floods; 2) develop a comprehensive combined hydraulic/hydrologic model of the Red River drainage basin to evaluate the flood mitigation benefits of Waffle storage during floods of various magnitude; 3) evaluate the impacts of temporary Waffle storage on downstream flood reduction and on the landscape through multiple field trials; 4) examine the economic feasibility ofthe Waffle concept to mitigate large springtime floods, including the costs of implementation, administration, and maintenance, as well as the benefits of mitigating flood damages; and 5) evaluate stakeholder receptivity to the concept. Simulated effects of the Waffle vary widely over the RRB and with different event scenarios. For one 1997 flood scenario, the largest simulated reduction in peak flood stage (as much as 6.2 feet) occurred in Fargo, North Dakota, and the least reduction (as little as 0.2 feet) occurred in Wahpeton, North Dakota. Numerous field trials conducted over the course of the study verified the effectiveness of the concept for flood mitigation and suggested that the Waffle approach can reduce overall flood volumes through increased evaporation and infiltration, increase soil moisture, and supplement groundwater reserves without adversely affecting the environment. The predicted flood mitigation benefits for several larger communities along the Red River as well as the estimated cost of implementing the Waffle were used to determine the net economic benefit of the concept. The estimated net benefit of Waffle implementation over the next 50 years was on the order of hundreds of millions of dollars, with some implementation scenarios exceeding $800 million in benefits. While the economic benefits of the Waffle estimated herein are alone sufficient to warrant evaluation of implementation options,