The so-called emergency communications at the time of catastrophic disaster etc. is considered to use ad hoc network effectively. Therefore, it is important to configure emergency communications networks that offer required sufficient QoS in disaster conditions using ad hoc networks. We arrange information and communication required after a disaster from the viewpoint of time elapsed since the disaster. We propose a practical communication model for developing ad hoc network configuration technologies. We analyze the performance of ad hoc networks on this model by using a network simulator. Changing the attributes of ad hoc network protocols keep the data arrival rates high even when terminal are moving very fast. We also discuss the effect on data arrival rate of the probability that a terminal will change directions and of blocked areas where travel is impossible.