In this study, a procedure is established for estimating and assessing the amount of flooding debris following a flood disaster. The per unit generation of flood disaster debris, which takes into account criteria such as the extent of housing damage as a function of inundation duration time, is examined. It is shown that this estimation procedure would make it possible to estimate debris discharge, which is helpful for the establishment of disaster management systems not just as emergency response measures, but also for pre-disaster planning. The proposed Relative Quantity of disaster Debris (ReQD) provides insight that makes it possible to ascertain the emergency response capability of local governments. The ReQDs of selected flood disasters in Japan are examined. For the establishment of effective emergency response systems, it is important to evaluate information on both the ReQD and the quantity of flood debris. From these facts, it is concluded that the implementation of ReQD can help in the establishment of effective support systems with a wide range of cooperative measures for districts in the process of flood recovery and reconstruction, as well as in the emergency response stage.