title: Qualitative simulation of bathymetric changes due to reservoir sedimentation: A Japanese case study.
abstract: Sediment-dynamics modeling is a useful tool for estimating a dam's lifespan and its cost-benefit analysis. Collecting real data for sediment-dynamics analysis from conventional field survey methods is both tedious and expensive. Therefore, for most rivers, the historical record of data is either missing or not very detailed. Available data and existing tools have much potential and may be used for qualitative prediction of future bathymetric change trend. This study shows that proxy approaches may be used to increase the spatiotemporal resolution of flow data, and hypothesize the river cross-sections and sediment data. Sediment-dynamics analysis of the reach of the Tenryu River upstream of Sakuma Dam in Japan was performed to predict its future bathymetric changes using a 1D numerical model (HEC-RAS). In this case study, only annually-averaged flow data and the river's longitudinal bed profile at 5-year intervals were available. Therefore, the other required data, including river cross-section and geometry and sediment inflow grain sizes, had to be hypothesized or assimilated indirectly. The model yielded a good qualitative agreement, with an R2 (coefficient of determination) of 0.8 for the observed and simulated bed profiles. A predictive simulation demonstrated that the useful life of the dam would end after the year 2035 (±5 years), which is in conformity with initial detailed estimates. The study indicates that a sediment-dynamic analysis can be performed even with a limited amount of data. However, such studies may only assess the qualitative trends of sediment dynamics.
authors.affiliation: College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, China.
authors.forename: Ahmed
authors.identifier: http://orcid.org/0000-0002-6903-1126
authors.initials: A
authors.lastname: Bilal
authors.affiliation: College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, China.|State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing China.|National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Nanjing, China.
authors.forename: Wenhong
authors.initials: W
authors.lastname: Dai
authors.affiliation: Department of Water Resources Engineering, Lund University, Lund, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Larson
authors.affiliation: Department of Water Resources Engineering, Lund University, Lund, Sweden.
authors.forename: Qaid Naamo
authors.initials: QN
authors.lastname: Beebo
authors.affiliation: College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, China.
authors.forename: Qiancheng
authors.initials: Q
authors.lastname: Xie
mesh_terms: D019015:Geologic Sediments; D007564:Japan; D014872:Water Movements; D014876:Water Pollution