Sains Malaysiana 45(1)(2016): 87–97

The Use of BLRP Model for Disaggregating Daily Rainfall Affected by Monsoon in Peninsular Malaysia

(Penggunaan Model BLRP untuk Mengasingkan Curahan Hujan Harian Terjejas oleh Monsun di Semenanjung Malaysia)

HARISAWENI, ZULKIFLI YUSOP* & FADHILAH YUSOF

Centre for Environment Sustainability and Water Security (IPASA)

Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim, Malaysia

Diserahkan: 16 Julai 2014/Diterima: 14 November 2014

ABSTRACT

Rainfall intensity is the main input variable in various hydrological analysis and modeling. Unfortunately, the quality of rainfall data is often poor and reliable data records are available at coarse intervals such as yearly, monthly and daily. Short interval rainfall records are scarce because of high cost and low reliability of the measurement and the monitoring systems. One way to solve this problem is by disaggregating the coarse intervals to generate the short one using the stochastic method. This paper describes the use of the Bartlett Lewis Rectangular Pulse (BLRP) model. The method was used to disaggregate 10 years of daily data for generating hourly data from 5 rainfall stations in Kelantan as representative area affected by monsoon period and 5 rainfall stations in Damansara affected by inter-monsoon period. The models were evaluated on their ability to reproduce standard and extreme rainfall model statistics derived from the historical record over disaggregation simulation results. The disaggregation of daily to hourly rainfall produced monthly and daily means and variances that closely match the historical records. However, for the disaggregation of daily to hourly rainfall, the standard deviation values are lower than the historical ones. Despite the marked differences in the standard deviation, both data series exhibit similar patterns and the model adequately preserve the trends of all the properties used in evaluating its performances.

Keywords: Bartlett Lewis rectangular pulse model; daily to hourly; disaggregation; Inter-monsoon; monsoon

ABSTRAK

Keamatan hujan adalah pemboleh ubah input utama dalam pelbagai analisis hidrologi dan pemodelan. Malangnya, kualiti data hujan selalunya lemah dan rekod data yang boleh dipercayai diperoleh pada jangka masa kasar seperti tahunan, bulanan dan harian. Rekod hujan selang pendek adalah terhad kerana kos yang tinggi serta kebolehpercayaan pengukuran yang rendah dan sistem pemantauan. Salah satu cara untuk menyelesaikan masalah ini adalah dengan mengasingkan selang kasar untuk menghasilkan yang pendek menggunakan kaedah stokastik. Kertas kerja ini menghuraikan penggunaan model segiempat denyut Bartlett Lewis (BLRP). Kaedah ini digunakan untuk mengumpul data 10 tahun setiap hari untuk menjana data setiap jam dari 5 stesen hujan di Kelantan sebagai kawasan wakil dipengaruhi oleh tempoh monsun dan 5 stesen hujan di Damansara dipengaruhi oleh tempoh antara monsun. Model dinilai berdasarkan keupayaan mereka untuk menghasilkan semula statistik model piawai dan hujan melampau yang diperoleh daripada rekod lampau ke atas penyampaian simulasi pengasingan. Pengasingan daripada setiap hari untuk hujan setiap jam dihasilkan melalui cara bulanan dan harian dan perbezaan yang rapat sepadan dengan rekod lampau. Walau bagaimanapun, bagi pengasingan daripada setiap hari untuk hujan setiap jam, nilai sisihan piawai adalah lebih rendah daripada rekod lampau. Walaupun perbezaan ketara dalam sisihan piawai, kedua-dua siri data menunjukkan corak yang sama dan model mengekalkan trend semua sifat secukupnya yang digunakan dalam menilai prestasinya.

Kata kunci: Antara-monsun; harian kepada jam; model segiempat denyut Bartlett Lewis; monsun; pengasingan

RUJUKAN

Ashraf, M.A., Maah, M.J. & Yusoff, I. 2011. Proposed design of anaerobic wetland system for treatment of mining waste water at former tin mining catchmet. Oriental Journal of Chemistry 27(3): 789-810.

Bo, Z., Islam, S. & Eltahir, E.A.B. 1994. Aggregation-disaggregation properties of a stochastic rainfall model. Water Resources Research 30: 3423-3435.

Burguen͂o, A., Martínez, M.D., Lana, X. & Serra, C. 2005. Statistical distributions if the daily rainfall regime in Catalonia (Northeastern Spain) for the years 1950 – 2000. International Journal Climatology 25: 1381-1403.

Chang, C-L., Lo, S-L. & Yu, S-L. 2006. The parameter optimization in the inverse distance method by genetic algorithm for estimating precipitation. Environmental Monitoring and Assessment 117: 145-155.

Cowpertwait, P.S.P. 1991. Further developments of the Neyman- Scott clustered point process for modeling rainfall. Water Resources Research 27: 1431-1438.

Cowpertwait, P.S.P., O’Connell, P.E., Metcalfe, A.V. & Mawdsley, J.A. 1996a. Stochastic point process modelling of rainfall. I. Single-site fitting and validation. Journal of Hydrology 175: 17-46.

Cowpertwait, P.S.P., O’Connell, P.E., Metcalfe, A.V. & Mawdsley, J.A. 1996b. Stochastic point process modelling of rainfall. II. Regionalisation and disaggregation. Journal of Hydrology 175: 47-65.

Debele, B., Srinivasan, R. & Parlange, J.Y. 2009. Hourly analyses of hydrological and water quality simulations using the ESWAT model. Water Resources Management 23: 303-324.

Deidda, R. & Puliga, M. 2006. Sensitivity of goodness-of-fit statistics to rainfall data rounding off. Physics and Chemistry of the Earth 31: 1240-1251.

Duan, J., Sikka, A.K. & Grant, G.E. 1995. A comparison of stochastic models for generating daily precipitation at the H.J. Andrews Experimental Forest. Northwest Science 69: 318-329.

Entekhabi, D., Rodriguez-Iturbe, I. & Eagleson, P.S. 1989. Probabilistic representation of the temporal rainfall process by a modified Neyman-Scott rectangular pulse model: Parameter estimation and validation. Water Resources Research 25: 295-302.

Glasbey, C.A., Cooper, G. & McGechan, M.B. 1995. Disaggregation of daily rainfall by conditional simulation from a point-process model. Journal of Hydrology 165: 1-9.

Gupta, H., Sorooshian, S. & Yapo, P. 1999. Status of automatic calibration for hydrologic models: Comparison with multilevel expert calibration. Journal of Hydrologic Engineering 4: 135-143.

Gyasi-Agyei, Y. 2005. Stochastic disaggregation of daily rainfall into one-hour time scale. Journal of Hydrology 309: 178-190.

Gyasi-Agyei, Y. 1999. Identification of regional parameters of a stochastic model for rainfall disaggregation. Journal of Hydrology 223: 148-163.

Gyasi-Agyei, Y. & Mahbub, S.M.P.B. 2007. A stochastic model for daily rainfall disaggregation into fine time scale for a large region. Journal of Hydrology 347: 358-370.

Hanaish, I.S., Ibrahim, K. & Jemain, A.A. 2011. Stochastic modeling of rainfall in peninsular Malaysia using Bartlett Lewis rectangular pulses models. Modelling and Simulation in Engineering 2011: Article ID 253735.

Hershenhorn, J. & Woolhiser, D.A. 1987. Disaggregation of daily rainfall. Journal of Hydrology 95: 299-322.

Hidayah, E., Iriawan, N., Nadjadji, A. & Edijatno 2010. Evaluating error of temporal disaggregation from daily into hourly rainfall using Heytos model at Sampean catchments area. Majalah IPTEK, Institut Teknologi Sepuluh November, Surabaya. pp. 23-28.

Koutsoyiannis, D. 2001. Coupling stochastic models of different timescales. Water Resources Research 37: 379-391.

Koutsoyiannis, D. 1994. A stochastic disaggregation method for design storm and flood synthesis. Journal of Hydrology 156: 193-225.

Koutsoyiannis, D. & Onof, C. 2001. Rainfall disaggregation using adjusting procedures on a Poisson cluster model. Journal of Hydrology 246: 109-122.

Koutsoyiannis, D. & Xanthopoulos, T. 1990. A dynamic model for short-scale rainfall disaggregation. Hydrological Sciences Journal 35: 303-322.

Koutsoyiannis, D., Onof, C. & Wheater, H.S. 2003. Multivariate rainfall disaggregation at a fine timescale. Water Resources Research 39(7): 1173.

Lo Presti, R., Barca, E. & Passarella, G. 2010. A methodology for treating missing data applied to daily rainfall data in the Candelaro River Basin (Italy). Environmental Monitoring and Assessment 160: 1-22.

Lu, Y. & Qin, X.S. 2012. Comparison of stochastic point process models of rainfall in Singapore. Proceedings of 2012 International Conference of World Academy on Science, Engineering and Technology (WASET) 68: 1234-1238.

Noor, M.J., Sultana, S., Fatma, S., Ahmad, M., Zafar, M., Sarfraz, M., Balkhyour, M.A., Safi, S.Z. & Ashraf, M.A. 2014. Estimation of anticipated performance index and air pollution tolerance index and of vegetation around the marble industrial areas of Potwar region: bioindicators of plant pollution response. Environmental Geochemistry and Health DOI: 10.1007/s10653-014- 9657-9.

Olofintoye, O.O., Sule, B.F. & Salami, A.W. 2009. Best-fit probability distribution model for peak daily rainfall of selected cities in Nigeria. New York Science Journal 2(3): 1-12.

Onof, C. & Wheater, H.S. 1994. Improvements to the modeling of British rainfall using a modified random parameter Bartlett- Lewis rectangular pulses model. Journal Hydrology 157: 177-195.

Onof, C. & Wheater, H.S. 1993. Modelling of British rainfall using a random parameter Bartlett-Lewis rectangular pulse model. Journal of Hydrology 149: 67-95.

Rodriguez-Iturbe, I., Cox, D.R. & Isham, V. 1988. A point process model for rainfall: Further developments. Proceedings of The Royal Society A: Mathematical, Physical and Engineering Sciences 417: 283-298.

Rodriguez-Iturbe, I., Cox, D.R. & Isham, V. 1987. Some models for rainfall based on stochastic point process. Proceedings of The Royal Society A: Mathematical, Physical and Engineering Sciences 410: 269-288.

Salarpour, M., Yusop, Z., Jajarmizadeh, M. & Yusof, F. 2014. Development of generalized feed forward network for predicting annual flood (depth) of a tropical river. Sains Malaysiana 43(12): 1865-1871.

Suhaila, J. & Jemain, A.A. 2008. Fitting the statistical distribution for daily rainfall in Peninsular Malaysia based on AIC criterion. Journal of Applied Sciences Research 4: 1846-1857.

Suhaila, J. & Jemain, A.A. 2007. Fitting daily rainfall amount in Peninsular Malaysia using several types of exponential distributions. Journal of Applied Sciences Research 3: 1027-1036.

Sultana, N., Akib, S., Ashraf, M.A. & Abidin, M.R.Z. 2015. Quality assessment of harvested rainwater from green roofs under tropical climate. Desalination and Water Treatment DOI: 10.1080/19443994.2015.1015307.

Valencia, D. & Schaake, Jr. J.C. 1973. Disaggregation processes in stochastic hydrology. Water Resources Research 9: 580- 585.

Verhoest, N., Troch, P.A. & De Troch, F.P. 1997. On the applicability of Bartlett-lewis rectangular pulses models in the modeling of design storms at a point. Journal of Hydrology 202: 108-120.

*Pengarang untuk surat-menyurat; email: zulyusop@utm.my