วันอังคารที่ 31 มกราคม พ.ศ. 2555

Thailand flood 2011 : Summary, Economic method of Assessment, and prevention

บทความโดย วรรณพงษ์ ดุรงคเวโรจน์
Picture Source:http://ireneismean.com/2012/01/11/q-pop-thailand-flood-relief-art-auction-and-sale/


            Flooding in Thailand in 2011 has killed 239 people and affected at least 12 million people. The flooding inundated about six million hectares of land, over 300,000 hectares of which is farmland, in 58 provinces, from Chiang Mai in the North to parts of the capital city of Bangkok near the mouth of the Chao Phraya. It has been described as "the worst flooding yet in terms of the amount of water and people affected". It takes time more than four months that Thai people stuck with inundation. The rich and the poor have the same social status in bad-living condition and loss their spirit. Seven major industrial estates were inundated by as much 3 meters. The agricultural output has been destroyed and it affects farmers who are poor and stuck with their debt obligation. Moreover, it’s worst when the flow of water went to Bangkok and first it affected the industrial estate. On October 8, 2011 the 10 metre high water flowed to  Nikom Rojna industrial estate and many manufacturing plants had been collapsed. Also the manufacturing plants, Honda, was left virtually inaccessible. Thailand is the world's 2nd largest producer of hard disk drives that is approximately 25% of the world's production.The industrial estate affected are Nikom Rojna Industrial Estate, Bang-paa In Industrial Estate,  Ayutthaya’s Saharattananakorn Industrial Estate ,Pathum Thani’s Navanakorn Industrial Park, Bangkadi Industrial Park and Baan –waa Hi tech Industrial Estate. Furthermore, it affect Japan that Japanese firm with plant in Thailand include Toyota, Honda, Hitachi, and Canon. Additionally, it affects the a loss in tourism despite its high season. Also,about food suppliers, the supply of food reduced about average 20% and lead to the problem of shortage of food and there is an import foods and water from other countries such as egg from Malaysia.



                Now, the inundation in Thailand is gradually resolved. Everything is better. The compensation from government primary is about 5,000 baht. There are also many schemes helped victim such as 30,000 baht for the wholly ruined house and 20,000 baht for partial ruined house. Even though government takes time to issue or announce the scheme to help the victim, it’s better than does not doing anything. Competence of government is needed to at least make sure to victims that they will not be neglected. In this 2011 inundation, NGOs (non-government organization) such as Thai-TV 3 is very important  to alleviate this destruction because government can not do anything perfect that they do not only help move victim but also add the alternative for donating. If we help them, it in turn contributes to our country further. And to prevent the next inundation, government needs three things. First is its administration. The second is specialist. The last and most importantly is active relief operation center.



               This severe inundation affects the asset market especially in zone of Rang Sit and Bang Bua Tong that are full of housing development. The new sale decline about 70 – 80% during flood but the sellers are worried about flooded consumers that will postpone their settlement or payment which it means sellers will not receive the cash from house built and developed. However, the condominium market is very vivid again since it’s slow in the beginning of year 2011. The entrepreneurs prepare to invest and construct new condominium. It’s possible that from this severe flood, people will decide to live in condominium more.



                About the city plan, it is very important because if our house located in lowland, when there is flood, our house will be flooded for a long time. Also, if we arbitrarily construct many building without considering about city plan whether it lies across the flood way or not,  flow of water will naturally find the other way to flow that it takes time very much. So, city plan is the answer of the question about why water flow slowly. There is a case about Chum Phon City Plan , policy maker or planner about city use the map and geological data to design the city plan and they announce to people that where is the lowland and where is the area of flood way. This terrible inundation teaches us about how important city plan is and we further have to elaborately consider about city plan. If we neglect city plan, it will be like this in the future. Government can not do everything perfect, we have to handle altogether.



                According to Strategic Committee for Reconstruction and Future Development’s plan about monetary provision, this organization wants to transfer the debt obligation 1.14 trillion baht from Financial Institutions Development Fund (FIDF) to Bank Of Thai for managing and settling so as to the decreased public debt from 42% to 18%. However, both principle and interest are too high that B.O.T. which is continually deficit can not settle this debt obligation. If there is transfer, it crucially affects the stability of B.O.T. because by the year 2017, B.O.T. will have 6.89 hundred billion baht. If B.O.T. receives more obligations in term of this 1.14 trillion baht, B.O.T. will no longer be central bank. The main duty of central bank is to maintain the economic stability and monetary system and can not settle this debt obligation. If B.O.T. print more money, it’s very wrong that in turn affect the creditability. However, from the debt ceiling, we can borrow more because now it’s only 42% from the imposed level of 60% that it means government is able to borrow money about 2 trillion baht. Another way is about official reserve that many people concerned about it. Nevertheless, to maintain the stability and creditability, serious and careful consideration is quite necessary.



Assessing method for flood

                There are many papers about flood damage assessment including research by B. Merz and research by Queensland Government, Natural Resources and Mines.

                1. According to research of B. Merz in Assessment of economic flood damage, Flood damages can be classified into direct and indirect damages. There are direct and indirect damage.



                Direct damages are those which occur because of the physical contact of flood water with humans, property (house, car ) or any other objects. Indirect damages are induced by the direct impacts and occur – in space or time – outside the flood event. Both types of damages are classified into tangible and intangible damages, depending on whether or not they can be assessed in monetary values. Tangible damages are damage to manmade capital or resource flows which can be easily specified in monetary terms, whereas intangible damage is damage to assets which are not traded in a market and are difficult to transfer to monetary values. Although the distinction in direct and indirect, and tangible and intangible damage is commonplace, interpretations and delineations differ. Some examples for the different types of damage are:



                – Direct, tangible: damage to private buildings and contents; destruction of infrastructure such as roads, railroads; erosion of agricultural soil; destruction of harvest; damage to livestock; evacuation and rescue measures; business interruption inside the flooded area; clean up costs.

                – Direct, intangible: loss of life; injuries; loss of memorabilia; psychological distress, damage to cultural heritage; negative effects on ecosystems.

                – Indirect, tangible: disruption of public services outside the flooded area; induced production losses to companies outside the flooded area (e.g. suppliers of flooded companies); cost of traffic disruption; loss of tax revenue due to migration of companies in the aftermath of floods.

                – Indirect, intangible: trauma; loss of trust in authorities.



                The costs of direct impacts are generally easier to quantify than indirect costs. Indirect impacts may have effects on time scales of months and years. Further, cascades of higher order impacts are conceivable such as macro-economic effects or long-term barriers to regional development in frequently flood-affected areas.



                About Spatial scales, flood damage assessments are performed on different spatial scales:



                – Micro-scale: the assessment is based on single elements at risk. For instance, in order to estimate the damage to a community in case of a certain flood scenario, damages are calculated for each affected object (building, infrastructure object, etc.).

                 – Meso-scale: the assessment is based on spatial aggregations.

Typical aggregation units are land use units, e.g. residential areas, or administrative units, e.g. zip code areas. Their size is in the order of magnitude of 1 ha to 1 km2.

                 – Macro-scale: large-scale spatial units are the basis for damage estimation. Typically, administrative units are used, e.g. municipalities, regions, countries.



                2. According to research of Queensland Government Natural Resources and Mines, Damage incurred as a result of significant flood events is broadly classified as follows

2.1Tangible damages—those that can be estimated directly in dollars.

2.2 Intangible damages—those that cannot be assessed in dollar terms. The subject of this bulletin is tangible damages, which can be further classified as either direct



or indirect.



                Tangible damages are those that can be readily measured in monetary terms. Damage to buildings and contents is considered tangible because it can be quantified in terms of replacement or restoration cost. Other damage—such as emotional trauma or loss of life—is considered intangible because it cannot be readily expressed in monetary terms. Direct damages are those that occur immediately and as a direct result of exposure to flood inundation. They include damage to both community infrastructure and private property.



Indirect damages occur as a consequence of direct flood impacts. They include reduced economic activity and individual financial hardship, as well as adverse impacts on the social



well-being of a community, and encompass disruptive impacts, including lost trading time and loss of market demand for products.



 Figure Show the damage of flood







There are a number of approaches that can be used to estimate tangible flood damages :



1. Survey of individual properties by a loss assessor to determine potential damages.

2. Application of stage–damage curves to assess potential damages.

3. Adoption of an average damage amount per building.



The following steps are involved in estimating flood damages:

1. Identify flood-affected properties and the likely height of inundation.

2. Select appropriate stage–damage curves for determining potential direct damages.

3. Apply stage–damage curves to estimate potential direct damages from flooding.

4. Estimate indirect losses.

5. Calculate total (direct and indirect) damages.



                Other than privately owned property, there are a number of assets that may be exposed to flood damage. For example, direct and indirect damages may be caused to: roads and transport infrastructure , parks and recreational facilities , hospitals, schools, police and fire stations, and other government buildings ,water, sewerage and drainage systems, and communications networks.  Annual maintenance expenditure figures and other documented historical costs can be used to develop locally specific damage costs.



Way to lessen the damage



                It includes warning system and drainage system

1. Warning System





                Flood Warning System measures rainfall amounts and monitors water levels in bayous and major streams on a real-time* basis to inform you of dangerous weather conditions. The stations contain sensors that transmit valuable data during times of heavy rainfall and during tropical storms and hurricanes. Some gages also measure wind speed and direction, barometric pressure, air temperature, road temperature and humidity. Accurate rainfall and bayou/stream level data help you and emergency management officials make critical decisions that ultimately can reduce the risk of property damage, injuries and loss of life. The Flood Control District urges you and your family to use this information and take the appropriate precautions during times of heavy rain and flooding. You are encouraged to monitor bayou/stream levels near your homes, places of work and areas along your daily commutes



History of the Flood Warning System



The installation of the gage system began in 1982 under the direction of the Flood Control District and initially included 13 gage stations. The first test of this system occurred during Hurricane Alicia in 1983, and the system provided invaluable information, including rainfall totals and bayou/stream level data that was not previously available. From 1983 to 2007, the number of gage stations increased to today’s total of 133, expanding the ability to monitor and gather information from many more bayous and streams.



 How the Information is Used



The primary function of the Flood Warning System is to transmit rainfall and bayou/stream level data for use by you and by government officials in taking steps to protect the public. The information received is collected and analyzed by the Flood Control District also to develop post-flood reports. These reports detail the extent and impact of flooding, including an approximation of the number of structures inundated from a flood. In addition, the Flood Control District uses this information to perform engineering analyses for identifying locations of future projects as well as to determine the effectiveness of constructed projects. When it begins to rain, data-collecting sensors at each gage station transmit rainfall amounts via radio frequency every time 0.04 inches of rain is measured by the sensor.



                Flood Warning System is acceptable and popular in many countries, also Thailand. Thus, there are many advantages of it, we should use it effectively.



2. Drainage System



                a drainage system is the pattern formed by the streams, rivers, and lakes in a particular drainage basin. A drainage basin is the topographic region from which a stream receives runoff, throughflow, and groundwater flow. Drainage basins are divided from each other by topographic barriers called a watershed. A watershed represents all of the stream tributaries that flow to some location along the stream channel. Drainage Systems include areas of the land surface that contribute flow to particular edges and points on the Hydro Network. A Catchment is a drainage area defined according to a certain standard. Watersheds represent any arbitrarily defined subdivision of the landscape into drainage areas. A Basin is an administratively defined land area that may contain many Catchments and Watersheds. Drainage areas are land areas that drain to elements on a Hydro Network. The determination of these area boundaries is necessary when modeling a hydrologic system. Drainage area boundaries are used in water availability studies, water quality projects, flood forecasting programs, as well as many other engineering and public policy applications. Accurate drainage boundaries are essential for accurate modeling studies.



Type of drainage system



1. Dendritic drainage system





                Dendritic drainage systems are the most common form of drainage system. In a dendritic system, there are many contributing streams (analogous to the twigs of a tree), which are then joined together into the tributaries of the main river (the branches and the trunk of the tree, respectively). They develop where the river channel follows the slope of the terrain. Dendritic systems form in V-shaped valleys; as a result, the rock types must be impervious and non-porous.



2.Parallel drainage system





                A parallel drainage system is a pattern of rivers caused by steep slopes with some relief. Because of the steep slopes, the streams are swift and straight, with very few tributaries, and all flow in the same direction. This system forms on uniformly sloping surfaces, for example, rivers flowing southeast from the Aberdare Mountains in Kenya



3. Trellis drainage system





                The geometry of a trellis drainage system is similar to that of a common garden trellis used to grow vines. As the river flows along a strike valley, smaller tributaries feed into it from the steep slopes on the sides of mountains. These tributaries enter the main river at approximately 90 degree angles, causing a trellis-like appearance of the drainage system. Trellis drainage is characteristic of folded mountains, such as the Appalachian Mountains in North America.



4. Rectangular drainage system

                Rectangular drainage develops on rocks that are of approximately uniform resistance to erosion, but which have two directions of jointing at approximately right angles. The joints are usually less resistant to erosion than the bulk rock so erosion tends to preferentially open the joints and streams eventually develop along the joints. The result is a stream system in which streams consist mainly of straight line segments with right angle bends, and tributaries join larger streams at right angles



5. Radial drainage system

               In a radial drainage system the streams radiate outwards from a central high point. Volcanos usually display excellent radial drainage. Other geological features on which radial drainage commonly develops are domes and laccoliths.



6. Deranged drainage system

                A deranged drainage system is a drainage system in drainage basins where there is no coherent pattern to the rivers and lakes. It happens in areas where there has been much geological disruption. The classic example is the Canadian Shield.



                There are many drainage systems in Thailand such as Kam Ling in Chumphon, the province in the south of Thailand, in order to relief the impact of flood when it’s in rainy season or faces the heavy storm. Thus, I think we should construct both warning system and drainage system in order to make sure we will be already safe from the next inundation.



Water Policy to prevent flood in the future

                        I collect many ways to prevent the inundation from many sources including



1. Professor Kriengsuk Chareonwongsak, Ph.D. said that

- Drainage system by flood plain. It needs expropriation the lowland in Bangkok to become a flood plain or we create the public park and create the basin. It will be recreational in general and the flood plain in the rainy reason. Flood plain needs a network for connecting to many canals around the capital.



- Create a huge dam at the shore in order to prevent scouring of sea water and also create the recreation.



- fix the city plan. We have to move the obstacle of water flow out.



- set the War Room to be a center about disaster and connect with other centers such as national disaster warning center



- Warning System in many canals that the data will automatically send to the center and it will be easy to analyze and forecast the future’s level of water



- Change the house’s model to prevent the flood such as house should have a space under the house.



2. Associate Professor Chaiwat Khayannavee said that



- improve drainage system to be more effective and increase the effectiveness in pump to drain water in Bangkok to the sea



-  require warning system



- Funds for disaster about not only flood but also everything to prepare the uncertain in the future.



3. Strategic Committee for Reconstruction and Future Development said that in long term we need



- improve or recover the head water area



- construct the dam more



- create the flood way in the future.



4. Senator Rossana Tositrakul offered government to set up the Ministry of Water to directly and obviously manage the whole water system in Thailand.



How to prevent Flood Damage

            There are many ways to prevent flood damage including



Home

1. Check your sump pump.

                 Clean the sump pump and pit, and test the pump by pouring water into the pit. Make sure the discharge hose delivers the water several feet away from the house to a well-drained area that slopes away from the house. If the hose outlet is too close to the house foundation or on flat ground, the water may simply recycle down through the house drain tile.



2. Preventing sewer backup.

                Sewer backup often occurs when storm water enters the sanitary sewer and causes an overload of water in the system. The overloaded system begins to backflow into household lines, causing sewer water to enter basements. One way to prevent sewer backup in your home is to plug or cap all sewer openings in the basement. This includes floor drains, toilets, sinks, showers, etc. After lifting toilets and taking off sink traps, you can cap openings with wooden plugs, expandable plugs, screwed caps or by other methods.



3. Move valuables to higher locations.

                Get items such as irreplaceable family photo albums, high school yearbooks, tax records, insurance policies and household inventories off the bottom shelves in the lower level of your home.



4. Move hazardous materials to higher locations.

                This includes paint, oil, cleaning supplies and other dangerous materials.



5. Move snow away from the house’s foundation.

                If the ground is sloped 1 inch per foot near the house, moving snow just 3 to 5 feet from the house will reduce problems.





5. Keep water out of window wells.

                 Since windows can’t withstand much pressure, build dams and contour the ground so water will naturally drain away from the house.



6. Get downspouts down in place

                You do it so that as snow melts they can carry the water away from the house. Using salt or a chemical to melt them free will probably damage the lawn.



7. Plan an escape route

                If certain roads or streets are known to flood easily. Where would you go if your home flooded — a local shelter, a family member or friend’s house?



8.Plan for pets.

                Pets aren’t allowed in shelters due to health regulations. If left behind, stressed pets can damage your house, and their safety is at stake too.



9.Assemble supplies in case the electricity goes off.

                Gather water, food that requires no refrigeration or cooking, a non-electric can opener, a battery-powered radio and flashlight, extra batteries.



10.Assemble supplies for a possible evacuation.

                Gather water, nonperishable food, paper plates/cups and plastic utensils, extra clothing and shoes, blankets or sleeping bags, a first aid kit and prescription medications, cash and credit cards, important phone numbers, special items for babies and the elderly.



11.Anchor fuel tank.

                 A fuel tank can tip over or float in a flood, causing fuel to spill or catch fire. Cleaning up a house that has been inundated with flood waters containing fuel oil can be extremely difficult and costly. Fuel tanks should be securely anchored to the floor.



12.Cover basement floor drains with permanent grids.

                Place a partially inflated inner tube around the drain, and top it with a square or two of plywood (not particle board). The plywood must be larger across than the inner tube to cover it. Brace this in place just as with the ball on the drain. Be prepared for some seepage.



13.Prepare appliances for flooding.

               Shut off appliances at the fuse box or breaker panel. Put freezers, washer, dryers and other appliances up on wood or cement blocks to keep the motors above the water level. If high water is imminent and large appliances can’t be moved, wrap them in polyethylene film, tying the film in place with cord or rope. The water will still get in, but most of the silt won’t so cleanup will be easier.



14.Shut off electricity to areas of the home that might flood.

              Even if floodwaters are not reaching electrical outlets, the risk of electrical shock to someone working in a flooded basement is high with electric motors in the furnace, freezer, washer, dryer and other appliances. Shut off electrical breakers or unscrew fuses. Don’t stand in water and turn off electrical switches. If this must be done, use a dry piece of wood or a plastic or rubber pole to do the switching, and stand on a block of wood or a plastic crate that doesn’t conduct electricity. If floodwaters are getting close to the electrical entrance box, call the power supplier and have the electrical supply to the house disconnected. If the floor is damp but not really flooded, ground fault circuit interrupters reduce the risk of using electricity. In newer homes, interrupters can be identified by the buttons between the top and bottom outlets. They can be added to any outlet or in an extension cord to turn off the power if an electrical fault occurs.



Family



1.Discuss what to do in case of a flood. Plan and practice an evacuation route.

2.Ask an out-of-state family member or friend to be your family contact. If family members get separated during an evacuation, each should get in touch with that contact. Make sure everyone has the contact’s phone numbers.



3.Discuss safe
emergency procedures.
Teach adults and older children where service
panels, water service mains and natural gas mains are and how to turn them off
if necessary.


4.Discuss the
situation with children honestly and openly. Hiding the situation from them
will probably be even more stressful.





The following are the safety measures to be taken before a
flood to prevent flood damage


If you are living in a flood prone area, you should elevate
and reinforce your home to protect yourself and your property from flood
hazards.


If your living area is susceptible to flooding, you should
elevate electric panel, water heater, furnace etc.


To prevent flood water from blocking the drains of your
home, sewer taps should be installed with appropriate check valves.


You should construct barriers like floodwalls, beams etc to
prevent flood water from entering into your building. This will help greatly to
prevent flood damage.


You should also seal the walls of your basement with waterproofing compounds so as to avoid seepage.


If you have been warned of an impending flood, you should
watch television or public communication media to gather more information about
the disaster to come.


If you have been warned of a flash flooding, then you should
not waste time waiting for instructions to evacuate but should move to a higher
ground as quickly as possible.


If you are preparing to evacuate, then you should secure
your home. If you have the time, move the valuables and essentials to an
elevated place or upper floor. You should also turn off all the utilities like
power supply, water supply, gas supply etc at its main source. Also disconnect
all electrical appliances, if possible. This will help to prevent flood damage
to the maximum extent possible.

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