Sungai Kulim merupakan sungai utama yang mengalir melalui bandar Kulim di selatan Kedah. Ia mengalir secara besar-besaran ke arah barat laut ke Sungai Perai di Seberang Perai. Pada tahun 2017, banjir telah berlaku di kawasan hilir Sungai Kulim. Fenomena ini mungkin disebabkan oleh intensiti hujan yang tinggi menyebabkan jumlah air yang tidak dapat dikawal dari hulu Sungai Kulim. Kesan banjir itu, hampir 100 buah rumah yang terletak di kawasan rendah telah musnah atau di bawah paras air dan penduduk tempatan diminta untuk berpindah ke pusat pemindahan. Oleh itu, kajian terhadap pelbagai purata pelepasan air berdasarkan tempoh pulangan 2, 3, 5, 10, 25, 50, 100, dan 200 tahun sepanjang 5 km panjang dan 200 meter lebar sungai hilir telah dijalankan. Unmanned Aerial Vehicle (UAV) digunakan untuk mengambil gambar ortho sungai dalam peratusan bertindih imej yang tinggi. Objektif utama dalam kajian ini adalah untuk mensimulasi banjir yang menggunakan perisian Sistem Analisis Sungai Hidrolik Pusat Analisis (HEC-RAS) yang dibina oleh US Army Corp. Perisian HEC-RAS digunakan untuk membantu analisis aliran saluran dan penentuan tahap air banjir oleh para penyelidik di seluruh dunia. Tahap air banjir boleh membantu menilai kesan kawasan hiliran disebabkan oleh intensiti purata hujan. Dengan menggunakan Digital Elevation Model (DEM) yang dihasilkan oleh perisian Agisoft Photoscan, HEC-RAS akan mensimulasikan kawasan banjir yang mungkin berlaku. Jumlah pelepasan air yang digunakan dalam simulasi ialah 44.25, 50.58, 57.59, 66.42, 77.58, 85.86, 94.08, dan 102.27 m3 / s. Pelepasan air adalah berdasarkan tempoh pulangan sebanyak 2, 3, 5, 10, 25, 50, 100, dan 200 tahun. Halaju maksimum, kedalaman maksimum, masa ketibaan dan peta sempadan banjir akan dihasilkan. Temuan ini dapat menghasilkan peta bahaya banjir dan meramalkan kawasan bahaya banjir. Kajian ini juga membantu pihak berkuasa untuk membina rancangan kecemasan untuk mengelakkan banjir berlaku di kawasan hilir Sungai Kulim. Selain itu, kajian ini dapat memberikan kesedaran kepada penduduk tempatan mengenai kawasan berisiko banjir.
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Sungai Kulim is the main river that flows through the town of Kulim in southern Kedah. It flows largely in a northwesterly direction to empty into the Perai River on the Seberang Perai. In 2017, flood occurred in downstream area of Sungai Kulim. This phenomenon probably due to high intensity of rainfall caused the uncontrollable amount of water discharge from upstream of Sungai Kulim. Impacts of that flood, nearly 100 houses located at the low-lying areas were destroyed or under water and the local residents were urged to move to the relief centre. Thus, study on various average water discharge based on return period of 2, 3, 5, 10, 25, 50, 100, and 200 years along 5 km length and 200 m width downstream river was conducted. The Unmanned Aerial Vehicle (UAV) Drone was used to capture the orthophoto of river in high percentage overlapping images. The main objective in this study is to simulate the flood extent using Hydraulic Engineering Center’s River Analysis System (HEC-RAS) software which is constructed by US Army Corp. HEC-RAS software was used to aid in channel flow analysis and flood water level determination by researchers around the world. The flood water level can helps evaluate effect of the downstream area due to average rainfall intensity. Using Digital Elevation Model (DEM) generated by Agisoft Photoscan software, HEC-RAS will simulate the area of flood probably occurred. The amount of water discharge used in the simulation were 44.25, 50.58, 57.59, 66.42, 77.58, 85.86, 94.08, and 102.27 m3/s. The water discharge were based on return period of 2, 3, 5, 10, 25, 50, 100, and 200 years. As a result, maximum velocity, maximum depth, arrival time and inundation boundary maps were produced. This finding was able to produce flood hazard map and predict risk area of flooding. This study also helped authorities to construct the emergency plan as to prevent flood occur in downstream area of Sungai Kulim. Besides, this study can give awareness to local residents of risk area on flood.
Flood hazard map of sungai kulim using high percentage of overlapping images captured by (UAV) drone / Ahmad Danial Kahfi Ghani