A river routing model for Orkla river Cao Tri Nguyen Hydropower Development Submission date: June 2017 Supervisor: Oddbjørn Bruland, IBM Norwegian University of Science and Technology Department of Civil and Environmental Engineering DECLARATION OF AUTHORSHIP I, Nguyen Cao Tri hereby declare that this master’s thesis titled “A routing model for Orkla river” and the work presented in it are my own and has been generated by me as the result of my own original research. I confirm that: 1. This work was done wholly or mainly while in candidature for a research degree at the Norwegian University of Science and Technology. 2. Where any part of this thesis has previously been submitted for a degree or any other qualification at this University or any other institution, this has been clearly stated. 3. Where I have consulted the published work of others, this is always clearly attributed. 4. Where I have quoted from the work of others, the source is always given. With the exception of such quotations, this thesis is entirely my own work. 5. I have acknowledged all main sources of help. 6. This thesis is based on work done by myself with the guidance of my supervisor Professor Oddbjørn Bruland and co-supervisor Frode Vassenden. Signature: Nguyen Cao Tri Date and Time: 8th of June, 2017, Trondheim, Norway ACKNOWLEDGEMENTS First of all I would like to convey my deepest appreciate towards my supervisor, Professor Oddbjørn Bruland, whose always support me from the beginning of the project til the successful completion of my work. I was impressed by his expertise and knowledge of hydraulic science and most of all, his guidance. Professor Oddbjørn continuously encourage me to provide better results and suggest the ideals for the topic. The communications did help me to go deeper into the topic and open up new ideals. I also would like to thank you Mr. Frode Vassenden from Trønderenergi. As a mathematician and a hydrologist, Mr. Frode gaves me a clear insight about the modeling and provided me all of the data needed for my analisys. Without his support I would hardly finish my thesis successfully. Futhermore I would like to express my sincere gratitude for Professor Knut Alfredsen and the research at the department, Abebe Girmay Adera for great help at the early stage of the project. Nguyen Cao Tri ABSTRACT In a large and complex hydropower system with multiple intake and outlet locations, the time lag in stream flow has a significant impact on downstream hydropower production. The impact becomes more important for power producer in an Energy Market. This is even more important in a Cascade Hydropower system where how to maximize utilize the water released from the upstream power plant is always an important question. At Orkla river, the Time Delay has been estimated since 2009 with a fix Time Delay of about 4 hours for Grana production flow and 12 hours for Brattset production flow. However, Time Delay and Time Constant has a mutual interaction and are vary in different flow conditions. Therefore, how to identify precisely Time Delay is an important task to look into in this thesis. The project aims to: a. Understand the flow pattern in Orkla river in different operations flow from Brattset and Grana power plan, both on dry and wet weather condition. b. Determine Time Delay in Orkla river in above conditions c. Have an overview of developed river routing model, and build a model that can reproduce the flow in Orkla river d. Produce a reference to estimate the Time Delay in other hydropower systems. Upon investigation, a brief summary of river routing models has been provided. Based on that, a model has been built to meet specific conditions at Orkla river. The model is verified to use with several historical data sets. Due to itæs simpleness, the model is fast and easy to embedded into current hydropower control system. Furthermore, a reference to estimate Time Delay was made for further research and application. TABLE OF CONTENTS I. INTRODUCTION ................................................................................................................ 1 1.1. Hydropower in Norway ................................................................................................. 1 1.2. Power market: ................................................................................................................ 1 1.3. Scope of the thesis .......................................................................................................... 2 II. OVERVIEW OF RIVER FLOW MODELLING ............................................................ 3 III. MATERIALS AND METHODOLOGY ......................................................................... 5 3.1. STUDY SITE.................................................................................................................. 5 3.2. INTRODUCTION TO HEC-RAS MODEL ............................................................... 8 3.2.1. Steady Flow Simulation using Hec-Ras ................................................................... 8 3.2.2. Unsteady Flow simulation using Hec-Ras .............................................................. 11 3.3. METHODOLOGY USES IN THE STUDY .............................................................. 11 3.3.1. Methodology ........................................................................................................... 11 3.3.2. Model Definition ..................................................................................................... 13 3.3.3. Re-Calibrate Hec-Ras model .................................................................................. 14 a) Method for calibration: ............................................................................................ 15 b) Lateral Flow calculation .......................................................................................... 16 c) Hec-Ras model setup ................................................................................................ 18 d) Derive Travel Time from Hec-Ras .......................................................................... 19 3.3.4. Estimation of the Time Constant and Time Delay for ADT model ........................ 22 3.3.5. The Correspondence of Time Delay and Geometry conditions.............................. 25 IV. RESULTS & DISCUSSION ........................................................................................... 27 4.1. HEC-RAS RECALIBRATION RESULTS ............................................................... 27 4.2. PARAMETERS FOR ADT MODEL ........................................................................ 29 4.2.1. Derived α and β results: .......................................................................................... 29 a) Results for Travel time generated by Hec-Ras ........................................................ 29 4.2.2. Time Constant and Time Delay after optimization ................................................. 31 4.3. ADT MODEL SIMULATION RESULT .................................................................. 37 4.3.1. Compare ADT model and Hec-Ras model ............................................................. 37 4.3.2. Correlation between Time Delay and geometry conditions ................................... 38 4.4. DISCUSSION ............................................................................................................... 39 References ............................................................................................................................... 40 APPENDIX A: MANNING’S COEFFICIENT TABLE BEFORE & AFTER RE- CALIBRATION ..................................................................................................................... 42 APPENDIX B: TIME CONSTANT AND TIME DELAY RESULTS .............................. 50 LIST OF FIGURES Figure 1: Open of Orkla river to the fjord, photo by Trondheim Havn/Åge Hojem .................. 5 Figure 2: Overview of Orkla Study Site ..................................................................................... 6 Figure 3: Methodology used in the study ................................................................................. 12 Figure 4: Calibrated Hec-Ras model by (Beckers, Jan 2014) .................................................. 14 Figure 5: Performance of Hec-Ras model by (Beckers, Jan 2014) .......................................... 15 Figure 6: Example of Optimization model used in the study ................................................... 23 Figure 7: Simulated flow from Hec-Ras period 1/6/2010 – 28/2/2012 .................................... 27 Figure 8:Simulated flow from Hec-Ras period 1/1/2015 – 30/12/2016 ................................... 27 Figure 9: Performance of Hec-Ras model after calibration, 8-15 Mar2015 ............................ 28 Figure 10: Simulated flow by Hec-Ras to derive ADT's parameters ....................................... 29 Figure 11: Travel time generated by Hec-Ras, section 110-55 ................................................ 29 Figure 12: Travel time generated by Hec-Ras, section 55-54 .................................................. 30 Figure 13: Travel time generated by Hec-Ras, section 54-22 .................................................. 30 Figure 14: Travel time generated by Hec-Ras, section 22-21 .................................................. 30 Figure 15: Travel time generated by Hec-Ras, section 21-2 .................................................... 31 Figure 16: Time constant and Time Delay for river