From the present study, the capability of the DANS method to be used to understand the spatial flow characteristics in shallow conditions over gravel- and cobble-bed have been confirmed. From the Chapter 3, the approach to estimate the double-averaging velocity profiles still need some improvements, especially about how to obtain general expression to determine bed roughness with variation of bed topography. Actually, some way to represent the bed roughness have been studied in the past years through numerical simulations or with another advanced method. The challenge is how to make it applicable for practical use in the field. It should be simple but reliable. Another thing is, the performance of DANS method for larger area, such as reach-scale, also need to be examined.
Chapter 5 69 Acknowledgements
Alhamdulillah wasyukurillah, finally this thesis is finished. First and foremost I praise and acknowledge Allah SWT, the most beneficent and the most merciful.
My humblest gratitude to the Holy Prophet Muhammad (Peace be upon him) whose way of life has been a continuous guidance for me. I thank to Allah SWT, for the way Allah SWT has upheld me and sustained me the throughout the study period.
I thank for Allah SWT for giving me strength, health and for being gracious.
In this great opportunity, I want to express my profound gratitude to my academic advisors Prof. Ichiro Tamagawa and Assoc. Prof. Morihiro Harada for their patience, motivation, enthusiasm, immense knowledge and assistance throughout my years in their lab and also my daily life, best supervision and supporting me during my study. They taught me and also showed me about what are the meaning become a PhD student and researcher. I feel that I have been trained, not only to be a beginner of researcher, but also in my mentality. I want to write my favorite quote here for them as a teacher, “It takes a big heart to help shaping our (students) little minds.”
I would like to say thank you to Prof. Yuichiro Fujita, who guided me during my two years as a research student and master student. His broad knowledge about river engineering research and also another field had inspired me to know and study more.
I express my sincere thank to Prof. Tomonao Kobayashi, for the evaluation of the thesis and for his valuable comments and advices.
Chapter 5 70
I should not forget to thank to all the teachers, especially Prof. Li Fusheng, Assoc. Prof. Wei Yongfen, Assistant Prof. Yasushi Ishiguro, and staffs of BWEL Program of Gifu University who always supported my study and helped me with documents-related things during these five and half years.
I also want to say my special thanks to all of my teachers from Andalas University, especially to my late teacher, Prof. Edison Munaf, who introduced me to the BWEL Program in Gifu University and encouraged me to continue my study to the higher level. I am also being grateful to have not only teacher but also mentor like Prof. Rahmiana Zein, who has inspired me to study more and taught me to never give up. I also want to say thank you to Prof. Safni, my academic advisor during my bachelor degree. She is a person who is also become one of my big inspiration, not only in academic field, but also in leadership.
I greatly appreciate the important assistance and help from all laboratory members during my study in Gifu University in this five and half years. I came to the Basin Hydrology Dynamic Laboratory with a poor skill and knowledge about river engineering. I could not be in this stage without receiving help and assistance from all of you. Thank you for giving me such a valuable time in laboratory.
I would like to give my very special and gratitude to my parents, my brother, and my big families, who have been supporting me in each and every step I take.
Thank you for patiently listening to all of my stories and thank you for your endless love. I also never forget to say thank you to my big families, who helped me to look after my parents when I was studying in Japan.
To all members of PPI (Indonesian Student Society in Gifu, Japan), I thank you for your moral support, for many helps and kind friendship. Specials thank to
Chapter 5 71 Dr. Aster Rahayu, Elsya Risky M.Eng., Dr. Edwina Zainal, Radhia Putri M.Sc., Weny Zuwirna M.Eng., Sofa Nur Azizah, Irwan Laming, Ali Rahmat M.AppSc., Antoni Pardede M.Sc., Amanatullah Savitri, Rio, and for other friends who I can write it one by one here. Thank you for many helps, kind friendship and great moments that we shared together.
Finally, I am very sorry that I am not able to mention all people who have given a contribution to this thesis. I am sure that some people will be missing to be mentioned. I would like to thank all of you.
Thank you very much Doumo Arigatou gozaimashita Terima Kasih
Chapter 5 72
List of Publications
1. Yanda, R., Harada, M., and Tamagawa, I.: The effect of sediment supply on hydraulic characteristics of flow over imbricated cobbles, Journal of Japan Society of Civil Engineering, Ser.B1 (Hydraulic Engineering), 72(4): 613-618, 2016.
http://doi.org/10.2208/jscejhe.72.I_613
2. Yanda, R. Harada, M., and Tamagawa, I.: Prediction of vertical velocity profile of streamwise velocity using double-averaging method. Proceeding of 37th IAHR World Congress, Kuala Lumpur, Malaysia, 2017.
3. Harada, M., Yanda, R., Onoda, and Y., Kayaba, Y.: Swimming fish habitat evaluation concept focusing on flow characteristics around the roughness layer in streams, Proc. of the 37th IAHR World Congress, Kuala Lumpur, Malaysia, 2017.
4. Yanda, R. Harada, M, and Tamagawa, I.: Study on double-averaged velocity profile for rough beds and low-flow conditions, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 74(4): 619-624, 2018.