Floods – what next ? . The PM announced 2 days ago that the government will allocate lots of money for flood mitigation under the RMK11. The DPM announced that there will be post-mortems to find out what caused the floods. [Rafizi announced that he is going to protest about the petrol prices]. Many jawatankuasa banjir will be formed in the coming months. . Let’s face it. Floods will always happen. There is no such thing as zero floods. [Floods even happen in the middle of deserts when freak thunderstorms cause the wadis to overflow]. We should not and cannot plan for zero floods. . What we should aim for is to minimise flood damage. The focus should always be to minimise or reduce damage caused by floods, not to eliminate floods. . A common solution is to widen and deepen the rivers. You always hear politicians and the people saying “mintak agensi yang berkaitan mengorek dan mendalamkan sungai untuk mengelakkan banjr”. This is not necessarily the right thing to do in the long-term. We have been widening and deepening our rivers for the past 50 years and the flood problems have not gone away. . We should work on these measures first : . (a) AVOIDANCE. Minimise occupancy of flooded areas. Flood prone areas in the country are well known and mapped. With proper land use planning, the state governments can control development in flood prone areas. Why do we keep allowing housing/commercial development in flood prone areas? If you keep allowing development in flood prone areas, you are only increasing the risk of flood damage. Keep development away from flood plains and riparian areas. There is not much we can do about the existing development but state governments need to be more disciplined with future development. . (b) PROTECT THE UPLANDS. Forests in the uplands help to moderate the floods. Vegetation help to reduce the speed of water. When the upper catchment (which is usually steep) is well-forested, the speed of flood waters moving down will be lower. Forested land allow water to seep into the soil better and reduce the volume of water moving downstream. When we clear forests in the upper catchment, we should expect greater volumes of water coming down and at greater speeds. Logging is a culprit but a bigger culprit is conversion of forests in the upper catchment into agriculture and other uses. In the case of Kelantan, the upper reaches of Sg. Kelantan (particularly the Sg. Nenggiri catchment), a lot of shit is happening. You know who is responsible. It is definitely not God. . (c) MINIMISE RUNOFF TO DOWNSTREAM. There are well-known measures to minimise the amount of water that runs off from a development. The JPS has clear guidelines (MASMA) on flood retention and measures to enhance permeability and reduce the speed of water running off from a development. It is a pity what much of it is not well implemented. We need to be strict on the requirements for on-site flood retention and reduction including the need to install flood retention ponds, permeable pavements and other best management practices advocated in the MASMA (Manual Saliran Mesra Alam). . (d) FLOOD CONTROL DAMS. These are (expensive) options that need to be considered. I think in the past several flood mitigation dams have been proposed for Kelantan but did not take off. They are expensive. And sometimes, there is no point in building dams if the states cannot control development upstream of the dams. The dams will be filled with sediment in no time (Cameron Highlands is a good example). Similarly, even if the government builds a dam in the upper Sg. Nenggiri to control the floods, the dam will be filled with sediment quickly because of all the development going on in Lojing. . (e) RIVER IMPROVEMENT. The last option is river widening and deepening and constructing flood protecting bunds/levees. Our engineers are good at this – and we have been doing this for the past 50 years – and I expect this to continue in the future. But this option has drawbacks. River improvements often increase the speed of water which then cause other problems including higher flood peaks. It may solve flooding in one place but could lead to problems in another place. River improvements often damage important habitats for fish and other river lifeforms. . . Flood mitigation is not easy. With good planning and creative design we can MINIMISE THE DAMAGE caused by floods. The focus must always be on minimizing DAMAGE. If an area is unhabitated with no development whatsoever, we can let that area flood. No point asking for zero floods everywhere. . Of course, besides mitigating floods, we need to strengthen our response to floods. These include better flood-forecasting capabilities and better flood relief mechanism. .
Posted on: Fri, 02 Jan 2015 01:18:38 +0000
Trending Topics
Recently Viewed Topics
© 2015