Isu perbandaran lagi...
eyh, tak tahu lar dengan bandar kita sekarang yea...
Papepun... Masalah perbandaran boleh dihindari dengan adenya langkah2 yang sejajar dengan era masa kini...
A flash flood is a rapid flooding of geomorphic low-lying areas - washes, rivers and streams - caused by the intense rain fall associated with a thunderstorm, or multiple thunderstorms. Flash floods can also occur after the collapse of an ice dam or a man-made structure, such as a dam, for example, the Johnstown flood of 1889. Flash floods are distinguished from a regular flood by a timescale less than six hours.
Flash flooding occurs when the ground becomes saturated with water that has fallen too quickly to be absorbed. The runoff collects in low-lying areas and rapidly flows downhill. Flash floods most often occur in normally dry areas that have recently received precipitation, but may be seen anywhere downstream from the source of the precipitation - even dozens of miles from the source.
•Physical damage- Structures such as buildings get damaged due to flood water. Landslides can also take place.
•Casualties- People and livestock die due to drowning. It can also lead to epidemics and diseases.
•Water supplies- Contamination of water. Clean drinking water becomes scarce.
•Diseases- Unhygienic conditions. Spread of water-borne disease
•Crops and food supplies- Shortage of food crops can be caused due to loss of entire harvest.
•Economic- Economic hardship, due to e.g. temporary decline in tourism, rebuilding costs, food shortage leading to price increase etc, especially to the poor.
Recently everyone is concern about the flash flood happened in Kuala Lumpur. Over this 2 weeks the weather in Klang Valley was very unusual and flash flood occurred in several places in KL in this 2 weeks.
Ini ade beberape ilmu dari pensyarah aku dulu....
MDM. WAN NURUL MARDIAH BT WAN MOHD RANI
Many people don't know why it happened and started to blame or point fingers to each other. I'm not surprise to see it, because everytime when anything wrong happened, everyone will started blame on each other. To me, I'll find out what is the main causes to lead on flash flood happened, it's no point for me to blame on others.
Here I just want share with you all my research and study on this situation for the past few years. Let's look at the geographical of Klang Valley, the major rivers are Klang River, Gombak River and Batu River. The other tributaries are Ampang River, Keroh River, Kerayong River, Kuyoh River, Damansara River, Penchala River and others.
We have two dams (Batu Dam and Klang Gates Dam) and few flood retention ponds but it's still not adequate to hold the rain water.
History of Major Floods
There are many major floods happened in Klang Valley since in 1920s. If you observe the frequent of floods, you can see the numbers of flood increasing in recent years.
The 1971 major flood was the worst ever in the history which happened almost whole Peninsular of Malaysia. It was believed the rainfall was 100 years return period, which is possible happen at least once in 100 years.
Let's look at some major flood pictures...
Causes of Floods
1.Rapid and Uncontrolled Development
3.Reduction of River Capacity
From 4 major causes, let me give some simple explains how it happens:
Look at the figure above, the land after development will become like 'water proof', the rain water will have no where to go through into the soil, so this phenomena will increase the surface water run off. If the drainage system are not design properly, the water run off will cause the flash flood happen.
Improper land development also will caused heavy siltation in drainage system, not only that, it also can caused land slide happened.
This is what happened on improper planning of a township, the heavy siltation in rivers will reduce the river capacity. It also destroyed the river ecosystem/diversity, this is why we hardly to see any living things like fish in the city's river.
Constrictions of river also another problem to create river water over flow from river. For example the picture above, the bridge was constructed lower than the flood level. That's why the bridge will block the water flow in the river and the back flow of water will spille out from the river.
Constrictions of structures also will disturbed the water flow during rainy days.
This is the very common situation we can see, illegal squatters and rubbish. I'm really sad that the mentality of Malaysian still treat our rivers as a rubbish dumping ground. I've seen on my own eyes a mamak shop in KL throw their rubbish directly into the river. Imagine if everyone does the same thing, our living place will become very sick.
Our river or drainage system is like artery in our body, once got any blockages, we will in trouble such as heart attack. Now, we are living in a 'heart decease' environment, it will burst anytime without any notice.
The business mentality here also never concern about the environmental impact, they just never let go any empty land or reserved forest to develop the properties for their big profit only. If they follow all the EIA (Environmental Impact Assessments) studies and some proper guidelines, this will reduce the flash flood happened.
Ni adalah nota yang aku dapat hasil kajian dari Pn. Nurul...
Kalu korang nk tau ag pasl banjir kilat ag...
Di sini yea...
Yang ini dari lecturer phd....