|
|
||
|
Floods In Sabah Flood Factors :: Floods in Sabah :: The Effects of Flood :: Flood Preventing Methods Introduction  Floods occur when water overflows from a river to a plain, which is
normally dry, and covers it. Floods frequently occur along river banks and the flat lands.
The potential for disaster is only too real for those who live in such areas. Although
floods normally cause little damage and difficulty, serious floods may also happen. Huge
floods can result in the loss of life and damaged property. Floods usually occur during
the rainy season, exacerbated by the human activities that can lead to unpredictable flash
floods after a heavy downpour.
In Sabah, floods are not a common occurrence because the average annual precipitation in the state is only 2,030 mm and is not widespread. Northern Sabah receives an annual rainfall of 2,800 mm. Between 2,000 mm and 2,800 mm of rain falls at the foothills. Lahad Datu and the south east of Crocker Range receive the least rainfall of less than 2,000 mm. The West and East Coasts of Sabah receive the most rainfall. Floods usually occur after a downpour in the low plains. Affected areas include Beaufort, Penampang, Papar and Tuaran. FLOOD FACTORS Several factors determine the occurrence of a flood. Among these factors are : Continuous rainfall Non-stop rainfall can cause floods. At the low lands, rain water flows to the river. A river full of rainwater then overflows onto the low lands, thus causing floods. Urbanization Many areas are modernized by urbanization. Earth from the hills is used to flatten the low lands. Many small river tributaries are covered with soil to turn them into bases for building construction. Such activities are some of the major factors in floods. River tributaries and valleys which used to flow with water are now covered up with soil. When the rain falls, waters from the hills flow to the low-lying areas, causing them to accumulate. Gradually more waters accumulate, causing flash floods to occur. River erosion Two factors explain the erosion of a river, namely, natural river erosion and erosion as a result of unmanaged human wastes. Erosion occurs naturally when, during rainfall, water in the river flows rapidly thereby eroding the river banks. Eventually the river banks collapse, forming a silt on the base of the river. Gradually the river becomes shallower. Unmanaged human and industrial wastes can also lead to shallower rivers and the restriction of riverflow. Shallow rivers caused by these two types of erosion cannot support waterfill, thereby resulting in floods. Forest barriers The forest is home to many species of animals and plants. It is also a stabilizer for the ecosystem that regulates the Earth’s temperature. Forests help absorb between 2% and 20% of the rain water. Waters that are absorbed are then channeled to the trees via the roots. Dew is released into the air by condensation, hence maintaining the natural moisture. Forest logging causes rain water to flow to the rivers without being absorbed and the rivers may not be able to support waterfill, thereby resulting in floods. Unplanned drainage system Floods in the town areas are due to the inadequate drainage system, which were too small and shallow to support a deluge during a heavy rainfall. Hence, flash floods occur. FLOODS IN SABAH Year 1996 Storm Greg resulted in a huge flood in Keningau at the northeastern part of Sabah resulting in the loss of many lives on 26 December 1996. Many of those who died were Indonesians working in that area. The Liawan, Pampang, Sinagang and Bayayo Rivers were flooded. Other affected areas included Tuaran, Papar, Kota Kinabalu, Penampang, Tawau and Sandakan. Year 1997 A flash flood hit the state capital and Penampang on 17 May 1997 after a heavy rain that began falling at around 3.00p.m. lasted till 8.00 pm in the same evening. This resulted in anxious moments and difficulties for many motorists as they were stuck in traffic jams in and around the town area. Many areas were exposed to the flood, including Putatan, Penampang, Luyang, Likas, Inanam and Menggatal. This flood occurred due to the imperfect drainage system in the district. Sandakan was also hit by flood as road construction had resulted in plugged drains. Many housing estates were affected and much property was damaged. Year 1999 The worst ever flood to hit Sabah happened on 6th January 1999. More than 2,000 residents in seven districts were evacuated to temporary shelters. The heavy rain fell non-stop for ten hours resulting in a huge flood. Penampang was worst hit by the flood. According to reports, 57 areas in seven districts were affected, the Penampang district leading with 22 affected areas, followed by Kota Kinabalu with 12 areas, Papar 10, Kota Belud 7, Tuaran 5, Beaufort 3 and Keningau 3. THE EFFECTS OF FLOOD Floods can bring a negative impact, including the loss of life. Some of the negative effects of floods are : Destruction of agricultural plantations Crops die in the prolonged accumulation of flood waters in the plantation areas. Rubber, cocoa, palm oil and rice are among the agricultural crops which cannot survive in such conditions. Such damage is a loss for farmers. Destruction of property A torrential flood can sink and wash away homes as well as damage various other property such as electrical goods, vehicles and the like. This is a loss for residents. Diseases The worst effect of floods is on one’s health. Floods can cause the accumulation of human waste in the flood waters. These flood waters can spread to other areas, resulting in diseases such as cholera and malaria. Deaths Floods often result in a loss of life especially in low-lying areas and along river banks. Loss to Government Floods damage public property such as roads, buildings, and telephone and electrical infrastructures. Floods can also bring about many kinds of diseases. The responsibility of repairing the damages and subsidizing medical equipment must be borne by the government. All these involve high maintenance costs. The government must also supply basic necessities such as food, drinking water and medicine, and set up temporary shelters for flood victims. Among the various methods used to prevent floods are : Proper drainage system Drains which have been shallowed due to silts must be cleaned constantly. Clean drains ensure proper water irrigation. River deepening project Most floods occur because of shallow rivers. Rivers which used to able to irrigate large amounts of water are now incapable of doing so. This is caused by silts and waste dumping. The solution to this problem is to deepen the rivers by removing all the mud and dirt in the river. Preserving forests Forest overlogging near the river banks can cause land erosion. This effect is similar to logging at the hillsides. Therefore, forests must be preserved to overcome floods. Forests are excellent natural barriers with which to absorb rain waters. They can also function as a sponge whereby they absorb the rain waters and then slowly release the waters to the rivers. They can filter earthly fluids into clean water. The forests can absorb 20% of the rain water. This water in turn is released into the atmosphere by condensation. This is the only way to reduce rain water. Controlling human activities Flash floods occur especially in town areas because of waste and industrial waste dumping into the rivers and drains. The society must be made aware of this negative act and stopped from continuing it by holding green campaigns. Certain statutory bodies should be made responsible for the cleanliness of the rivers and preventing them from becoming dumping areas. Floods are unavoidable when it comes to rain. However, they are preventable and ways must carried out to ensure that floods do not become a serious problem. People should also be made aware of this natural disaster.
|
Homepage
designed by Sabah State Library |
-- Best Viewed with IE in 800 X 600 resolution --
