Uncertainty in flood wave routing in a lateral inflow-dominated stream

The field of water resources engineering is concerned with the planning, design, construction, and operation of facilities for the management of water. In some situations, the so-called flood wave routing problem becomes an important part of answering questions related to planning, design, or operation. Traditional approaches to the solving the problem have relied on deterministic analysis techniques. However, current practice in the field is increasingly focusing on probabilistic techniques. This shift in focus allows the engineer to attach a level of assurance to a design, for example, a 90% probability that the plans will meet the operational requirements.;Adoption of probabilistic techniques is hampered by a lack of data. This study investigates a small, lateral-inflow dominated stream within this context. Such streams are poorly studied whereas large rivers with little or no lateral inflow are more frequently investigated. The necessary data were obtained for Pistol Creek, Tennessee, USA. A total of 158 cross sections were available for analysis which makes this one of the most detailed studies of its kind. The result in this study is that probability distributions are developed for key parameters in the flood wave routing problem. For two of the parameters, this appears to be the first reported example of the development of such data.;The probability data is subsequently used to simulate the movement of a flood wave in the channel, and investigate the relative sources of uncertainty: upstream and lateral boundary conditions, and routing parameters. It was found that the uncertainty due to upstream and lateral boundary conditions was significantly greater than the uncertainty due to routing parameters. Subsequently, a synthetic example is also developed for comparison of the results for Pistol Creek to a situation without the heavy influence of lateral inflow. In this synthetic example it was found that the uncertainty in the upstream boundary condition was greater than the uncertainty due to routing parameters. However, differences in the Pistol Creek were greater than in the synthetic example, highlighting the significant importance of lateral inflow in a small stream.