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As we know, flood can be defined as a body of water, rising, swelling and overflowing land not usually thus covered. Also, overflowing of the bank of a stream, lake or drainage system of water onto adjacent land as a result of storm, ice melt, tidal action and channel obstruction. Its negative impacts are flood can threaten lives, disrupt social and economic activities and destroy properties, causes distress and recovery can be costly both to individuals and the government, and deterred new investments in the flood prone area.So,some flood management control must be taken into action to minimise or prevent more losses from happening in the future.
Food Mitigation Project
Flood mitigation involves the managing the control of flood movement, such as redirecting flood run-off, rather than trying to prevent it altogether. It is management of people, through measures such as evacuation and dry/wet proofing properties for example. The prevention of flooding can be studied on a number of levels, individual properties, small communities and whole towns or cities. The costs of protection rise as more people and property are protected.
For a smaller case like small scale of flood and needed for a only individual properties protection,for example houses and human properties,there are systems that property owners purchase and fit to their home to stop water entering their house. These systems work on blocking doors, windows and air vents with boards as shown in picture below:
But then.if the scale of flood is higher and include larger communities,thus different kind of flood mitifation is suggest to protect lives and others properties.When more homes, shops and infrastructure are threatened by the effects of flooding, then the benefits of greater protection is worth the additional cost. Temporary Flood Defenses can be constructed relatively quickly in certain locations and provide protection from rising flood waters.
Rivers running through large urban developments will often have been controlled and channeled. These channels or canals will have a fixed capacity and if flood water flows exceed this capacity then the city will flood. Over time defenses will have been constructed to minimize the effects, and this will generally be through raising the sides of the river channel with embankments, walls or levees. The large number of people and huge value of infrastructure at risk in cities, means that protection works of high cost can be justified.
The most effective way of reducing the risk to people and property is through the production of flood risk maps. Most countries in the developed world will have produced maps which show areas prone to flooding events of known return periods.Engineers will use this map to identify low lying areas which need flood defences.Below is the map of flood map in Malaysia which shown area at risk or prone to experience flood if volume of rain is exceeding from normal day:
C:\Users\User\Downloads\flood area_penisular.pngFlood prone area in peninsular of Malaysia
C:\Users\User\Downloads\flood area_ss.png Flood prone area in Sabah & Sarawak
By identified areas of known flood risk, the most sustainable way of reducing risk is to prevent further development in those known flood risk areas. It is important for at-risk communities to develop a comprehensive Floodplain Management plan.Those communities that participate in the National Flood Insurance Program must agree to regulate development
in the most flood prone areas. Communities should assign a floodplain administrator to oversee the management of the floodplain development permit process.
Besides,there are already some of flood mitigation projects in Malaysia that can be follow if we want to solve the flood problem in area that our group discuss from earlier.For example Sg Muda Flood Mitigation Project and SMART Project. We will elaborate and see in detail this magnificient project to become guide for the ways to overcome flooding.
Sg Muda Flood Mitigation Project
Sg. Muda, which is located within the boundary of Kedah and Pulau Pinang with a catchment area of 4,210 km2 and 180 km length begin from Muda Dam and flows across district of Baling, Sik and Kuala Muda. Water supply for agricultural, industrial and domestic sector for both Penang and Kedah is the key role of the river.
The catchment often being flooded on the rainy season from April to May and from September to November every year. Many problems raised when flood keep on worsening each year (e.g. riverbank erosion, river pollution and reduction of water resources). The flood event which occurred on October 2003 was the worst compared to previous event in 1988, 1995 and 1998.
To reduce flooding events that often occur in it's catchment. Flood threats are caused by several factors, which are;
i) Steep catchment
ii) Inadequate size of river to contain flow (Overflow)
iii) Buildings built on flood prone area
iv) Developments in the catchment provide flood problems at agricultural areas and towns which are near to the river (e.g. Sik, Baling, Kuala Ketil, Jeniang and Pekula)
v) Inadequate size of original barrage to flow excess water during flood events.
vi) Heavy and continuous rain in the catchment
Scope of Work
Project area which are proposed by JICA encompasses along Sg. Muda and 3 towns are;
i) From Sidam Bridge to river mouth of Sg. Muda (40 km)
ii) Sg. Muda and Sg. Ketil in town of Kuala Ketil (6km)
iii) Sg. Ketil in town of Baling (3.6 km)
vi) Sg. Chepir in town of Sik (2km)
Scope of work for Sg. Muda Flood Mitigation Project are;
i) To deepen and widen river, and to construct bund along Sg. Muda from Sidam Bridge to river mouth of Sg. Muda (40km)
ii) Sg. Muda river mouth improvement work
iii) Construction of new barrage (15 bay with capacity of 1,400 cumec)
iv) Construction of new railway bridge
v) Construction of drainage systems and flood control gate
vi) Riverbank erosion control
vi) Relocation and readjustment of public amenities (e.g. pump and water supply pipe, electric and telephone cable, PWD bridges, irrigation pump and related works)
SMART is an acronym for Stormwater Management and Road Tunnel. It is an innovative project of the Government of Malaysia to solve flooding problem in the City Centre of Kuala Lumpur at Klang River and around the vicinity of Masjid Jamek, Jalan Tun Perak caused by Klang River overflowing its banks. The project also serve to ease the traffic congestion problem between Kuala Lumpur City Centre and Southern gateway at Sungai Besi. The Unique feature of SMART is the 3 km double-deck motorway within the 9.7 km tunnel which starts near the Kampung Pandan roundabout in the city centre and ends at Kuala Lumpur-Seremban Highway next to TUDM Airfield at Sungai Besi.
A sophisticated and modern flood Detection System (FDS) provides real time flood forecasting information. This enables the efficient and safe management at the operation of the tunnel. For the safety of motorists, the motorway traffic is unidirectional and safety features such as ventilation shafts, cross passages, vms, fire extinguisher and air ventilators have been incorporated in the design in compliance with international and Malaysian Standards. This project has been a great challenge for the local engineers involved in the management and construction of the SMART Project as it runs below congested roads, near sensitive structures and through varied geological ground conditions.
Objectives of SMART
Primary objective of SMART: To alleviate flooding problem at the Kuala Lumpur city centre due to stormwater from the Klang-Ampang catchment.
Added benefit of SMART: To ease traffic congestion at the southern main gateway (TUDM at Sungai Besi) to the city centre.
The tunnel begins at Kg. Berembang where the Diversion Weir at the confluence of Sg. Klang/ Sg. Ampang and Offtake Structure divert flood water to the Holding Pond. The water then flows through the Intake Bell Mouth structure into the Tunnel and discharge at the Attenuation Pond at Taman Desa flood water is stored in this pond before releasing to Sg. Kerayong through the Twin Box Culvert.
SMART Control Centre is in operation 24 hours a day. Once high flow is measured at the confluence, the SMART Control Centre will send a signal to the Motorway Control Centre to evacuate the traffic from the tunnel. After ensuring the road tunnel is cleared, the traffic compartment will be flooded. Once the flood has receded, the tunnel will be cleaned and opened to the public.
Operational Modes of The Smart Tunnel.
Mode 1 :
When weather is fair with little or no rain falling and traffic is allowed in the tunnel.
Mode 2 :
activated when moderate rain falls and the flow rate recorded at the confluence of upper Sungai Klang/Sungai Ampang ('L4' flow station) is 70-150 m3/s.
excess flood water will be diverted to SMART holding pond and only the lower drain of tunnel will be used to convey flood flow to the Desa attenuation pond. 50 m3/s will be discharged to City Centre.
road traffic tunnel will remain opened to road users.
Mode 3 :
activated when major storm event occurs and flood model forecasts a flow rate of 150 m3/s or more at L4. Only 10 m3/s will be discharged to city centre.
traffic will be evacuated from the road tunnel.
if heavy rain storm stops early or due to some specific circumstances, then the traffic tunnel will not be flooded.
road tunnel will be re-opened to traffic within 2-8 hours after closure.
activated if heavy rain storm prolongs, usually will be confirmed 1-2 hour after Mode 3 is declared.
road tunnel will be used for passage of flood flow after traffic evacuation completed.
road tunnel will be re-opened to traffic within 4 days of closure.