Bencana banjir yang dahsyat telah berlaku di Kuala Krai, Kelantan pada
Disember 2014. Kejadian bencana banjir itu, telah memberikan impak yang ketara
seperti merosakkan infrastruktur dan akibatnya hampir 1,600 rumah telah musnah.
Kejadian banjir yang ekstrim ini telah membunuh 25 penduduk manakala 45,467
penduduk di Kuala Krai, Kelantan telah dipindahkan dari rumah mereka. Hujan lebat
berterusan lebih daripada tiga hari (21 hingga 23 Disember, 2014) telah mencatatkan
rekod hujan sebanyak 1,295 mm, bersamaan dengan jumlah hujan yang biasanya dilihat
dalam tempoh 64 hari. Hasilnya, paras air di tiga sungai utama, Sungai Galas di
Dabong, Lebir Sungai Tualang dan Sungai Kelantan di Jambatan Gueillemard,
meningkat di atas paras air berbahaya. Ia adalah penting untuk menganggarkan sejauh
mana banjir banjir tertakluk kepada tebing sungai pecah dan banjir tempatan.
Selanjutnya, pemetaan banjir boleh dilakukan untuk menggambarkan dataran banjir
bagi kegunaan pembangunan pada masa depan. Terdapat dua soalan utama daripada
kajian ini yang perlu dijawab; adakah ramalan kedalaman banjir semasa adalah tepat
dan bagaimakah cara untuk menganggarkan banjir supaya mangsa banjir dapat
dikurangkan. Objektif kajian ini adalah untuk mensimulasikan kejadian banjir pada
Disember 2014 dan untuk menentukan banjir banjir tempatan di Kuala Krai. Kejadian
banjir di Kuala Krai dari (1-31 Disember 2014) telah dikaji dengan menggunakan
Rainfall-Runoff Inundation Model (RRI), yang dibangunkan oleh Universiti Kyoto,
Jepun. Model RRI mensimulasikan proses air larian hujan dan banjir dengan serentak
berdasarkan dua dimensi persamaan resapan-gelombang. Model ini memerlukan data
input seperti data taburan hujan, ketinggian, aliran sungai, penggunaan tanah dan
keratan rentas sungai. Arc-GIS digunakan untuk memproses ketinggian dan
penggunaan tanah sebelum mengimport ke model RRI. Di samping itu, keadaan
sempadan dan input data diambil daripada data kajian lapangan yang dikutip dari
kedalaman banjir (2-4 Mac 2015) dan data keratan rentas bagi sungai pula
menggunakan ADCP. Pengukuran ADCP Sungai Galas dan Sungai Lebir telah
dijalankan pada 10-12 Jun, 27-29 Julai, dan 3-5 Ogos 2015. Keputusan RRI
menunjukkan dua luahan puncak dan pembanjiran telah berlaku kira-kira pada 19 dan
25 Disember 2014 ; 9,338.60 m3/s dan 14,593.03 m3/s magnitud yang sama yang telah
direkodkan oleh Laporan JPS pada tahun 2014. Penemuan ini membawa kepada
kesimpulan bahawa model RRI adalah sangat berguna sebagai alat menganalisis banjir.
_______________________________________________________________________________________________________
A devastating flood disaster occurred at Kuala Krai, Kelantan on December
2014. The flood disaster had given a significant destructive impact to the infrastructure
and as a result almost 1,600 homes were lost or destroyed. This extreme flood event
killed 25 villages and forced 45,467 people in Kuala Krai, Kelantan to be evacuated
from their homes. Continuous heavy rain for over three days from the 21st to the 23rd of
December, 2014 was set a rainfall record of 1,295 mm, equivalent to the amount of rain
usually seen in a span of 64 days. As a result, the water levels of three major rivers, the
Sungai Galas in Dabong, the Sungai Lebir in Tualang and the Sungai Kelantan in
Jambatan Gueillemard, rose above the dangerous water levels. It is essential to estimate
the extent of flood inundation subjected to river bank burst and local flood. Further,
flood inundation map could delineate floodplain for future developments. There are two
main questions from this study need to be answered which are how accurate the current
prediction on flood depth and how to estimate flood inundation so that the flood victims
could be minimised. The objectives of this study are to simulate flood event on
December 2014 and to determine local flood inundation in Kuala Krai. Flood
occurrences and inundation at Kuala Krai from (1st-31st December 2014) was studied
by using the Rainfall-Runoff Inundation Model (RRI) which is developed by Kyoto
University, Japan. The RRI model simulates the process of rainfall runoff and
inundation simultaneously based on two-dimensional diffusion-wave equations. This
model needs input data such as rainfall, elevation, stream flow, land use and crosssectional
of river. The Arc-GIS is used to process the elevation and land use data before
importing to the RRI model. Further, the boundary condition and input data was
received from a field survey data collected from flood depth (2nd-4th March 2015) as
well as from the cross-sectional field survey measurements using ADCP. The ADCP
measurement for Sungai Galas and Sungai Lebir were conducted on 10th-12th June, 27th-
29th July, and 3rd-5th August 2015. The RRI results show the two peak discharges and
inundations occurred approximately on the 19th and 25th December 2014; 9,338.60 m3/s
and 14,593.03 m3/s to be similar magnitude to the ones reported by DID 2014 Flood
Report. These findings led to the conclusion that the RRI model is useful as a flood
analysis tool.
Flood inundation mapping usingrainfall-runoff inundation model at Kuala Krai, Kelantan on December 2014 / Muhamad Zulhilmi Abdul Latif