ISO/TR 11651:2015

TECHNICAL ISO/TR
REPORT 11651
First edition
2015-08-15
Estimation of sediment deposition
in reservoir using one dimensional
simulation models
Estimation du dépôt de sédiments dans le réservoir en utilisant des
modèles de simulation à une dimension
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
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ii © ISO 2015 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Definitions . 2
4 Units of measurement . 2
5 Principles of quasi-unsteady sediment modelling . 2
6 Principles of unsteady flow models . 2
6.1 General . 2
6.2 Governing equations . 3
6.3 Numerical techniques for solution of governing equations . 6
6.3.1 Explicit finite-difference methods . 7
6.3.2 Implicit finite-difference methods . 7
6.3.3 Finite element methods . 7
6.3.4 Finite volume methods . 8
6.4 Sediment transport . 8
7 Data requirements .10
7.1 Selection of model boundaries .12
7.2 Cross-section data .12
7.2.1 General.12
7.2.2 Manning’s n values .13
7.2.3 Movable bed and dredging .13
7.3 Stage data.13
7.4 Velocity data .13
7.5 Discharge data .13
7.6 Lateral inflows and withdrawals .14
7.7 Sediment data . 14
8 Formulation, calibration, testing and validation of models .15
8.1 Formulation of numerical models .15
8.1.1 Hydrology .15
8.1.2 Geometry .16
8.1.3 Selection of transport equation .16
8.1.4 Bed mixing and armoring algorithm .16
8.2 Preliminary tests .16
8.3 Computational grid and time step.17
8.4 Convergence testing .18
8.5 Boundary and initial conditions .18
8.6 Calibration .18
8.7 Validation .19
8.8 Predictive simulation .20
8.9 Sensitivity testing .20
8.10 Specific models .20
9 Uncertainties .21
9.1 Model parameters .21
9.2 Data for model development, testing and application .21
9.3 Governing equations .22
9.4 Numerical approximations to governing equations .22
Annex A (normative) Models and case studies .24
Bibliography .25
Foreword
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The committee responsible for this document is ISO/TC 113, Hydrometry, Subcommittee SC 6,
Sediment transport.
iv © ISO 2015 – All rights reserved

Introduction
Storage reservoirs built across rivers or streams lose their capacity on account of deposition of sediment.
Surveys indicate that world-wide reservoirs are losing their storage capacity, at an annual rate of about
one percent, due to accumulation of sediments. The impacts of sedimentation on the performance of the
reservoir project are manifold. Some of the important aspects are the following:
a) reduction in live storage capacity of the reservoir;
b) accumulation of sediment at or near the dam may interfere with the functioning of water intakes
and hence is an important parameter in deciding the location and level of various outlets;
c) increased inflow of sediment into the water conveyance systems and hence to be considered in the
design of water conductor systems, desilting basins, turbines, etc;
d) sediment deposition in the head reaches may cause rise in flood levels;
e) the location and quantity of sediment deposition affects the performance of the sediment sluicing
and flushing measures used to restore the storage capacity.
Hence, prediction of sediment distribution in reservoirs is essential in the following:
a) feasibility studies during planning and design of various components of new projects;
b) performance assessment of existing projects.
The most simple and earliest models to predict the sedimentation processes in reservoirs are the
empirical ones. The trap-efficiency curves derived from records of existing reservoirs are among the
most commonly used empirical methods. Recently, due to better understanding of the fundamentals
of reservoir hydraulics and morphology, along with the rapid growth of computational facilities,
development and application of mathematical models have become a normal practice.
Compared to empirical methods, the mathematical approach of the sediment distribution enables more
time and space dependent and more accurate modelling. A large number of mathematical models have
been developed during the past few decades. Flow in the reservoir can be represented by the basic
equations for conservation of momentum and mass of water and sediment.
TECHNICAL REPORT ISO/TR 11651:2015(E)
Estimation of sediment deposition in reservoir usi
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