Rainfall Monitoring of Flood Events in Indonesia Using Gsmap and Rain Gauge Data
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i THESIS RAINFALL MONITORING OF FLOOD EVENTS IN INDONESIA USING GSMAP AND RAIN GAUGE DATA NYOMAN SUGIARTHA POSTGRADUATE PROGRAM UDAYANA UNIVERSITY DENPASAR 2013 i THESIS RAINFALL MONITORING OF FLOOD EVENTS IN INDONESIA USING GSMAP AND RAIN GAUGE DATA NYOMAN SUGIARTHA NIM 1191261007 MASTER DEGREE PROGRAM GRADUATE STUDY OF ENVIRONMENTAL SCIENCE POSTGRADUATE PROGRAM UDAYANA UNIVERSITY DENPASAR 2013 THESIS RAINFALL MONITORING OF FLOOD EVENTS IN INDONESIA USING GSMAP AND RAIN GAUGE DATA Thesis to get Master Degree at Graduate Study of Environmental Science Postgraduate Program Udayana University NYOMAN SUGIARTHA NIM 1191261007 MASTER DEGREE PROGRAM GRADUATE STUDY OF ENVIRONMENTAL SCIENCE POSTGRADUATE PROGRAM UDAYANA UNIVERSITY DENPASAR 2013 ii AGREEMENT SHEET THIS THESIS HAS BEEN APPROVED ON 5 SEPTEMBER 2013 Knowing Director of Head of Graduate Study Postgraduate Program of Environmental Science Udayana University Postgraduate Program Udayana University Prof. Dr. dr. A.A. Raka Sudewi, Sp.S (K). Prof. Made Sudiana Mahendra, PhD. NIP. 195902151985102001 NIP. 195611021983031001 iii RAINFALL MONITORING OF FLOOD EVENTS IN INDONESIA USING GSMAP AND RAIN GAUGE DATA Thesis Thesis to get Master Degree at Graduate Study of Environmental Science Postgraduate Program Udayana University By: NYOMAN SUGIARTHA Approved by Committee Committee Member Committee Member Dr. Ir. I Wayan Nuarsa, MSi. Ass. Prof. Dr. Takahiro Osawa NIP. 196805111993031003 Committee Member Committee Member Prof. Ir. I Wayan Arthana, MS, PhD. Prof. Dr. I Wayan Budiarsa Suyasa, MS. NIP. 196007281986091001 NIP. 196703031994031002 Head of Committee Prof. Made Sudiana Mahendra, PhD. NIP. 195611021983031001 iv This Thesis Has Been Examined and Assessed by the Examiner Committees of Postgraduate Program Udayana University on 19 August 2013 Based on Letter of Agreement from Rector of Udayana University Number : 1498/UN.14.4/HK/2013 Date : 16 August 2013 The Examiner Committees are: Head of Examiner: Prof. Made Sudiana Mahendra, PhD. Members: 1. Prof. Dr. I Wayan Budiarsa Suyasa, MS. 2. Prof. Ir. I Wayan Arthana, MS, PhD. 3. Dr. Ir. I Wayan Nuarsa, MSi. 4. Ass. Prof. Dr. Takahiro Osawa v STATEMENT FREE FROM PLAGIARISM The undersigned below: NAME : Nyoman Sugiartha NIM : 1191261007 DATE OF BIRTH : Singaraja, 26 October 1970 ADDRESS : Perumahan Tegal Jaya Permai I/28, Dalung, Kec. Kuta Utara, Kab. Badung, Bali THESIS TITLE : Rainfall Monitoring of Flood Events in Indonesia Using GSMaP and Rain Gauge Data Hereby declare that the scientific work is plagiarism free. If in the future prove to have plagiarism in scientific work, and then I am willing to accept sanctions in accordance with the regulations of the Minister of Republic Indonesia number 17 in 2010 and regulations applicable in the Republic of Indonesia. Denpasar, August 2013 I respectfully, Nyoman Sugiartha vi ACKNOWLEDGEMENTS “Om namah Shivaya”, praise to Almighty God for blessing me invaluable self realisation and strong courage to complete this thesis. I would like to highly dedicate this work to my beloved late father and late father in law, who live in eternity and always guide and inspire me about the essence of life and love. I would like to express my thanks and gratitude to the Ministry of Education and Culture Republic of Indonesia for awarding me scholarship under Beasiswa Unggulan scheme to pursue Double-Degree Master Program in Yamaguchi University, Japan. I would like to express my deeply thanks and appreciation to Udayana University and Prof. Made Sudiana Mahendra as a Head of Graduate Study of Environmental Sciences of Udayana University for giving me opportunity to undertake the Double-Degree Master study. It appreciably enhances my knowledge and experience. I would like to convey my high appreciation and gratitude to my supervisors Prof. Kakuji Ogawara and Prof. Tasuku Tanaka, a Director of Center for Remote Sensing and Ocean Sciences (CReSOS) Udayana University for their enthusiastic guidance throughout the study. I sincerely thank to Dr. Haruma Ishida, an assistant professor in the Laboratory of Instrumentation and Information Engineering, Department of Mechanical Engineering, Yamaguchi University for his kindly guidance and assistances. Many thanks to the GSMaP Project for granting permission to use satellite data. The GSMaP Project was sponsored by JST-CREST and is promoted by the JAXA Precipitation Measuring Mission (PMM) Science Team. Many thanks to Mr. Agit Setiyoko, a BMKG staff at Ngurah Rai Airport Station, Bali for assistance with rain gauge data access. I thank also to I.D.N. Nurweda Putra, a Doctoral Course student in the Department of Mechanical Engineering, Yamaguchi University for helpful discussion on using OpenGrads software. Last but not least, I would like to express my indebtedness to my beloved family: my mother, my mother in law, my wife, my daughters, my son and my sisters who always praying and wishing me all the best. I would like to express my great gratitude to them for their fortitude and patience during my study in Yamaguchi University. Denpasar, August 2013 Author vii ABSTRACT Indonesia which lies in equatorial region is recognised having potential of large rainfall amount during rainy season. As a consequence, the rainfall related natural disaster, such as flood is prominent and spreading in many places throughout the country. Study on the rainfall as well as its accurate monitoring is therefore one of fundamental importance for understanding flood mechanism and early warning. This study evaluates rainfall intensity variation and patterns preceding flood events in Indonesia for the period of 2003-2010 using the GSMaP_MVK satellite-based rainfall product with one hour and 0.1o x 0.1o resolutions and rain gauge station data as a benchmark. The analysed data are 3-hourly average and daily accumulation time steps. The chosen research locations are Medan City, Pekanbaru City, Indragiri Hulu Regency, Samarinda City and Manado City. The study also verifies accuracy of the GSMaP_MVK in detecting rain/no- rain conditions with respect to the rain gauge data for the flood events over the research locations using continuous and categorical verification statistics. Visual comparison of the two observation data have been made in the forms of time- series and scatter plots based on point to point analysis method. Graphical comparisons of the GSMaP_MVK with the rain gauge data show discrepancies in capturing rainfall events and intensity. The GSMaP_MVK performs underestimation for the most areas, except Samarinda City, which is overestimated. Short-term period rainfall pattern is the most frequent occurred preceding flood events for the entire study areas which indicate that the areas are more susceptible to flash floods and river overflows. Overall, the GSMaP_MVK product provides promising potentiality for the application of monitoring rainfall conditions preceding flood events over the research locations. Statistical verifications reveal that on average, correlation coefficients are (0.22-0.54) and (0.65-0.83) for 3-hourly and daily scale, respectively. While, probability of rain detections (PODs) are (0.57-0.75) and (0.93-0.99), accordingly. Keywords: rainfall, monitoring, accuracy, GSMaP_MVK, rain gauge, flood events viii ABSTRAK Indonesia yang berada di daerah ekuator dikenal memiliki potensi jumlah curah hujan yang besar pada musim hujan. Sebagai konsekuensinya, bencana alam yang berhubungan dengan curah hujan menjadi menonjol dan tersebar di banyak tempat. Studi tentang curah hujan dan juga akurasi dalam pemantauannya, oleh karena itu merupakan salah satu hal mendasar yang penting untuk memahami mekanisme banjir dan peringatan dini. Studi ini mengevaluasi variasi intensitas dan pola curah hujan yang terjadi sebelum kejadian banjir di Indonesia untuk periode tahun 2003-2010 dengan menggunakan produk curah hujan dari satelit yaitu GSMaP_MVK yang memiliki resolusi 1 jam dan 0.1o x 0.1o dan dengan data penakar curah hujan sebagai pembanding. Data yang dianalisis adalah rata-rata interval 3 jam-an dan akumulasi harian. Lokasi penelitian adalah Kota Medan, Kota Pekanbaru, Kabupaten Indragiri Hulu, Kota Samarinda dan Kota Manado. Studi ini juga memverifikasi akurasi dari GSMaP_MVK dalam mendeteksi kondisi adanya hujan atau tidak ada hujan terhadap data dari penakar curah hujan untuk kejadian banjir di lokasi penelitian dengan menggunakan verifikasi statistik kontinu dan kategori. Perbandingan visual dari kedua data pengamatan disajikan dalam bentuk runut waktu dan diagram hambur berdasarkan metode analisis titik ke titik. Perbandingan secara grafis dari data GSMaP_MVK dan data penakar curah hujan menunjukkan adanya perbedaan dalam memantau kejadian curah hujan dan intensitasnya. Data GSMaP_MVK menunjukkan estimasi lebih kecil dibandingkan dengan data penakar curah hujan untuk sebagian besar lokasi, kecuali Kota Samarinda yang menunjukkan estimasi lebih besar. Pola curah hujan dengan interval singkat adalah paling sering terjadi sebelum kejadian banjir untuk semua lokasi yang mengindikasikan bahwa lokasi tersebut lebih rentan terhadap banjir bandang dan banjir oleh luapan sungai. Secara keseluruhan, produk GSMaP_MVK memberikan potensi yang menjanjikan dalam aplikasi untuk memantau kondisi curah hujan sebelum kejadian banjir di lokasi penelitian. Verifikasi statistik menunjukkan bahwa secara rata-rata koefisien korelasi adalah 0.22-0.54 untuk data 3 jam-an dan 0.65-0.83 untuk data harian. Sementara itu, angka probabilitas pemantauan terjadinya hujan adalah 0.55-0.75 untuk data 3 jam-an