River Flow Modelling and Forecasting

Advances in computer technology, in the technology of communication and in mathematical modelling of processes in the hydrological cycle have recently improved our potential to protect ourselves against damage through floods and droughts and to control quantities and qualities in our water systems. This development was demonstrated in a 1983 post-experience course at Wageningen University where an international group of experts reviewed successful modelling techniques and described the design and operation of a number of forecasting and control systems in drainage basins and river reaches of various sizes and under various geographical and climat­ ological conditions. A special effort was made to bridge the gap between theory and practice; case studies showed that each forecasting system was designed to meet a set of specific requirements and they illustrated that the forecasting system can only be expected to operate reliably if, on the one hand, it is based on sound theoretical concepts and methods and if, on the other hand, it is robust so that, also under adverse conditions, it will continue to collect and process the necessary input­ data and produce correct and timely signals. We were pleased to meet with encouragement for preserving the course material and making it available to a wider public. This was effected by the team of authorf who elaborated, updated and harmonized the materia in two stages; first into an issue of our university department and finally into the manuscript of this book.

Contenu

1. Introduction.- 1.1 Objectives.- 1.2 Objectives of forecasting.- 1.3 Criteria for successful forecasts.- 1.4 Systems approach.- 1.5 Principles and elements of river flow forecasting.- 1.6 Concluding remarks.- Symbols.- References.- 2. Deterministic Catchment Modelling.- 2.1 Introduction.- 2.2 Linearity/Non-linearity.- 2.3 Analysis/Synthesis.- 2.4 Illustrative example.- 2.5 Linear treatment of catchment behaviour.- 2.6 Non-linear treatment of catchment behaviour.- Symbols.- References.- 3. Theory of Flood Routing.- 3.1 Continuity equation for unsteady flow.- 3.2 Momentum equation for unsteady flow.- 3.3 Equations of characteristics for unsteady flow.- 3.4 Boundary conditions in flood routing.- 3.5 The finite difference approach.- 3.6 Characteristic finite difference schemes.- 3.7 Explicit finite difference schemes.- 3.8 Implicit finite difference schemes.- 3.9 Linearisation of the St. Venant equations.- 3.10 Simplification of the St. Venant equations.- 3.11 Comparison of hydraulic solutions.- 3.12 Nature of hydrologic methods.- 3.13 Linear conceptual models.- 3.14 Comparison of linear hydrologic models.- 3.15 Calibration of linear models.- 3.16 Non-linear hydrologic models.- Symbols.- References.- 4. Low Flow Sustained by Ground Water.- 4.1 Introduction.- 4.2 Discussion of rainfall-discharge relations.- 4.3 Examples.- Symbols.- References.- 5. Forecasting Meltwater from Snow-Covered Areas and from Glacier Basins.- 5.1 Introductory remarks.- 5.2 The snow cover and its determination.- 5.3 The determination of the meltrates.- 5.4 Practical methods to determine the meltrates.- 5.5 Operational forecasting equations for glacier basins where past records are available.- 5.6 Thermal and capillary retention capacity.- 5.7 Long range, seasonal forecasting.- Symbols.- References.- 6. Time-Series Methods and Recursive Estimation in Hydrological Systems Analysis.- 6.1 Introduction.- 6.2 The simplest first order, linear hydrological model.- 6.3 More complicated linear hydrological models.- 6.4 Recursive estimation of a simple time-series model.- 6.5 Recursive estimation of general linear time-series models.- 6.6 Model structure (order) identification.- 6.7 Flow modelling for the river Wyre.- 6.8 Time-variable parameter estimation.- 6.9 Salinity variations in the Peel Inlet-Harvey Estuary Western Australia.- 6.10 Time-series analysis and flow forecasting.- 6.11 Flow forecasting and the Kalman Filter.- 6.12 The Extended Kalman Filter.- 6.13 Conclusions.- Acknowledgements.- Symbols.- Appendix 1. The Microcaptain Computer Program Package.- References.- 7. Relationship between Theory and Practice of Real-Time River Flow Forecasting.- 7.1 Link between theoretical chapters and case studies.- 7.2 Model input fields.- 7.3 Theory versus practice in real-time river flow forecasting.- 7.4 Conclusions.- References.- 8. Case Studies in Real-Time Hydrological Forecasting from the UK.- 8.1 Introduction.- 8.2 Real-time flow forecasting system for the river Dee.- 8.3 The Haddington flood warning system.- 8.4 An on-line monitoring, data management and water quality forecasting system for the Bedford Ouse river basin.- 8.5 Discussion.- Symbols.- References.- 9. River Flow Simulation.- 9.1 Introduction.- 9.2 Finite difference methods.- 9.3 Numerical properties.- 9.4 The Delft Hydraulics Laboratory method.- 9.5 Practical aspects.- 9.6 Case study: Flood control of the rivers Parana and Paraguay.- 9.7 Strategy for implementation of forecasting models.- Symbols.- References.- 10. The Forecasting and Warning System of 'Rijkswaterstaat' for the River Rhine.- 10.1 Introduction.- 10.2 General description of Rijkswaterstaat and its warning services.- 10.3 Organization of the riverflood warning system.- 10.4 The empirical forecasting model.- 10.5 The multiple linear regression model.- 10.6 Low flow forecasting.- References.- 11. Short Range Flood Forecasting on the River Rhine.- 11.1 Introduction.- 11.2 Flow forecasting.- 11.3 A deterministic hydrological model for the river Rhine.- 11.4 A stochastic real-time forecasting model.- 11.5 Conclusions.- Symbols.- References.- 12. Design and Operation of Forecasting Operational Real-Time Hydrological Systems (Forth).- 12.1 Introduction.- 12.2 Components of a FORTH system.- 12.3 Selection of forecasting procedures.- 12.4 Forecast updating and evaluation (WMO, 1983).- 12.5 Benefit and cost analysis of hydrological forecasts.- 12.6 Examples of established FORTH systems.- Symbols.- References.- Annex I.- Annex II.- 13. Case Studies on Real-Time River Flow Forecasting.- 13.1 Introduction.- 13.2 The Santa Ynez River, California, USA.- 13.3 Derwent River system, England.- 13.4 Orchy River system, Scotland.- Symbols.- References.