Sains Malaysiana 40(11)(2011): 1277–1284

Fenomena Kehujanan di Semenanjung Malaysia

Berdasarkan Indeks Kerpasan Piawai

(Peninsular Malaysia Rainfall Phenomenon Based on Standard Precipitation Index)

Siti Aishah Hanawi*

Pusat Pengajian Teknologi Maklumat, Fakulti Teknologi dan Sains Maklumat

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E. Malaysia

Wan Zawiah Wan Zin, Abdul Aziz Jemain, Rokiah @ Rozita Ahmad

Pusat Pengajian Sains Matematik, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E. Malaysia

Received: 4 August 2010/ Accepted: 7 February 201

ABSTRACT

The purpose of this study was to identify the rainfall distribution patterns in Peninsular Malaysia using Standard Precipitation Index at different time scales which are one month, six months and twelve months. Daily rainfall data for 75 rain-gauge stations covering four zones which are Northwest, West, Southwest and East for 33 years: 1975 – 2007 were considered. The results of the analysis showed that the dispersion value for occurrence of wet/dry condition increases with higher time scale. Results on related variables which are duration, severity and inter arrival time showed that the values for maximum, average and standard deviation at all zones also increased with higher time scales. The Southwest zone was found to consistently experience longer duration of wet condition compared to dry condition, while the West zone has a relatively higher standard deviation for all variables apart from intensity.

Keywords: Daily rainfall; distribution patterns; Standard Precipitation Index; time scales

ABSTRAK

Kajian ini bertujuan mengenal pasti pola taburan kehujanan di Semenanjung Malaysia menggunakan Indeks Kerpasan Piawai bagi skala masa yang berbeza iaitu sebulan, enam bulan dan dua belas bulan. Data kajian adalah data hujan harian dari 75 stesen tadahan hujan yang merangkumi empat zon iaitu Barat Laut, Barat, Barat Daya dan Timur untuk 33 tahun; 1975 – 2007. Hasil kajian mendapati nilai serakan bagi frekuensi keberlakuan keadaan basah/kering bertambah dengan peningkatan skala masa. Kajian pemboleh ubah berkaitan iaitu tempoh, keparahan dan selang ketibaan mendapati wujud peningkatan dalam nilai-nilai maksimum, purata dan sisihan piawai di setiap zon dengan bertambahnya skala masa yang digunakan. Seterusnya, zon Barat Daya secara konsisten mengalami tempoh keadaan basah yang lebih lama berbanding tempoh keadaan kering manakala zon Barat pula menghasilkan nilai sisihan piawai yang paling tinggi berbanding dengan zon lain untuk kesemua pemboleh ubah kajian kecuali intensiti.

Kata kunci: Indeks Kerpasan Piawai; hujan harian; pola taburan; skala masa

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*Corresponding author; email: aishah@ftsm.ukm.my