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Title:	Pemodelan statistik ribut ekstrim dan profil statistik ribut di semenanjung Malaysia
Authors:	Noratiqah Mohd Ariff (P59508)
Supervisor:	Abdul Aziz Jemain, Prof. Dr.
Keywords:	Ribut ekstrim Profil statistik Rain and rainfall
Issue Date:	21-Jul-2014
Description:	Dua kaedah yang biasa digunakan untuk memproses maklumat daripada data curahan hujan ialah analisis berasaskan tetingkap (ABT) dan analisis peristiwa ribut (APR). ABT mentakrifkan cerapan hujan sebagai jumlah hujan terkumpul di dalam satu selang masa yang telah ditetapkan. Oleh itu, cerapan hujan daripada ABT dianggap tidak menggambarkan peristiwa hujan yang sebenar. APR pula menggunakan data curahan hujan pada skala yang lebih halus untuk mentakrifkan cerapan ribut sebagai jumlah hujan terkumpul bagi tempoh masa suatu peristiwa ribut. Bagaimanapun, APR jarang digunakan kerana kekurangan data yang berskala kecil berbanding data curahan hujan harian. Kini, data curahan hujan per jam lebih mudah didapati dan APR yang menganggap amaun serta tempoh masa ribut sebagai pemboleh ubah rawak boleh digunakan dengan meluas. Tujuan kajian ini adalah untuk menganalisis curahan hujan setiap jam dari 45 stesen hujan di Semenanjung Malaysia menggunakan APR. Ini dilakukan dalam tiga tahap iaitu perbandingan ABT dan APR, pembinaan profil statistik ribut dan pemodelan statistik ribut ekstrim. Perbandingan ABT dan APR dilihat berdasarkan statistik perihalan dan ciri berskala cerapan hujan dan ribut. Ciri statistik kedua-dua cerapan menunjukkan perbezaan yang jelas manakala ciri berskala kedua-duanya mengimplikasikan kewujudan sifat penskalaan mudah. Profil statistik bagi komponen ribut yang terdiri daripada kekerapan, tempoh masa, tempoh kering antara peristiwa dan amaun ribut dikaji dari segi taburan ruang melalui peta kontur dan taburan masa melalui kajian trend yang menggunakan ujian Mann-Kendall dan butstrap serta kajian titik perubahan yang menggunakan ujian Pettitt. Dua indeks ribut iaitu keamatan ribut (KR) dan indeks penumpuan ribut (IPR) digunakan dalam analisis kelompok. Peristiwa ribut didapati berbeza di empat kawasan berlainan di Semenanjung Malaysia hasil daripada keunikan bentuk geografinya dan pengaruh musim monsun. Pemodelan statistik ribut ekstrim pula dijalankan melalui pembentukan lengkung keamatan-tempoh-kekerapan (IDF) bagi mewakili hubungan antara komponen ribut ekstrim. Lengkung IDF dibina menggunakan beberapa kaedah dan persamaan IDF berlainan yang dibandingkan menggunakan tiga indeks ketepatan padanan iaitu pekali variasi punca min ralat kuasa dua (PPVPMRK), min peratus perbezaan mutlak (Δ) dan pekali penentuan (R²). Beberapa kaedah pembinaan lengkung IDF dibincangkan dalam proses pengitlakan yang dilakukan secara berparameter menggunakan kaedah L-momen. Lengkung IDF turut dibina menggunakan algoritma L-momen serantau dalam proses penyerantauan dan menggunakan kaedah empirikal melalui kedudukan memplot. Kaedah multi kriteria VIKOR diaplikasikan untuk membandingkan lengkung IDF yang diperoleh daripada sembilan kedudukan memplot yang dipertimbangkan dan enam daripadanya didapati sama-sama berkelebihan. Akhir sekali, hubungan IDF diperoleh berdasarkan analisis dwivariat dengan menggunakan kaedah copula yang mana copula Frank bersyarat didapati sesuai digunakan. Perbezaan yang kecil diperhatikan antara kesemua set lengkung IDF yang dikaji dan semua kaedah ini didapati sesuai bagi membentuk lengkung dan menggambarkan hubungan IDF peristiwa ribut di Semenanjung Malaysia. Oleh itu, penyelidik dalam pelbagai bidang dapatlah memanfaatkan kaedah dan hasil kajian mengikut kesesuaian matlamat masing-masing.,Two commonly used methods in processing information from rainfall data are the window based analysis (WBA) and storm event analysis (SEA). WBA defined observed rainfall as the accumulated rainfall in a predetermined interval. Therefore, the observed rainfall from WBA does not represent actual rainfall event. SEA, on the other hand, uses finer scaled data to define observed storm as the accumulated rainfall within the duration of a storm event. However, it is less used due to lack of smaller scaled data compared to daily rainfalls data. Nowadays, hourly rainfall data is easier to obtain and SEA which treat storm amount and duration as random variables can be used widely. The aim of this research is to analyze hourly rainfall from 45 rainfall stations in Peninsular Malaysia using SEA. This is done in three phases which are comparing WBA and SEA, building a statistical profile for storms and modelling extreme storms. Comparisons between WBA and SEA are performed based on the descriptive statistics and scaling properties of observed rainfall and storm. The statical properties of both observations show clear differences while both of their scaling properties show the existence of simple scaling behaviour. The statistical profile of storm's components which consist of storm occurrence, duration, dry period between events and amount are investigated by looking at their spatial distribution through contour plots and temporal distribution through trend analysis which uses Mann-Kendall and bootstrap test as well as change point analysis using Pettitt test. Two storm indices, storm intensity (SI) and storm concentration index (SCI), are used in cluster analysis. Storms are found to be different in four different regions of Peninsular Malaysia due to its unique geography and the monsoon season. The statistical model for extreme storms is done through the intensity-duration-frequency (IDF) curves to represent the relationship between the components of extreme storm. IDF curves are built using various methods and IDF equations which are compared by using three goodness of fit indices consisting of the percentage for coefficient of variation of root mean square error (PCVRMSE), mean percentage of absolute difference (Δ) and the coefficient of determination (R² ). Some methods of constructing the IDF curves are discussed in the generalization process which is done parametrically using the L-moment method. IDF curves are also built by using the regional L-moment algorithm in the regionalization process and by using empirical method with plotting positions. The multi criteria VIKOR method is applied in comparing IDF curves from nine plotting positions where six of them are found to be equally superior. Lastly, IDF relationship is obtained using the copula method in bivariate analysis where the conditional Frank copula is found to be suitable. The differences between all these IDF curves are found to be small and all the different methods are suitable to build IDF curves and to represent IDF relationship for storms in Peninsular Malaysia. Hence, researchers in various fields could benefit from the methods and the results of this study according to the suitability of their objectives.,Bachelor
Pages:	288
Call Number:	QC942.N646 2014 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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