MODERN APPROACHES IN FLOOD DISASTER RISK MANAGEMENT BY ENGR. DR. QAZI TALLAT MAHMOOD FEBRUARY 28,2018
INTRODUCTION Iudatios due to floods have the potetial to cause fatalities, displacemet of people, ad damage to the eviromet ad thus severely compromise ecoomic developmet. Floodig accouts for 40% of all the atural hazards worldwide ad half of all the deaths caused by atural disasters. Floods are atural pheomea which caot be preveted; evertheless, some huma activities cotribute to a icrease i the likelihood ad adverse impacts of flood. Food risk, that may be defied as the product of probability of flood ad associated damage, icreases with ecoomic developmet give that potetial damage icreases. Resistace strategies of flood risk maagemet are maily based o the costructio of levees/spurs.
The Mai Elemets of Ma s Respose to Flood Hazard Socio ecoomic processes Physical processes The Flood Hazard Experieced, predicted Perceptio Respose to Flood Hazard Flood Cotrol Adjustmet Abatemet Protectio
HUMAN RESPONSE TO Flood Adjustmet FLOOD HAZARD Flood Abatemet Flood Protectio
POSSIBLE ADJUSTMENT TO FLOOD HAZARD NO ADJUSTMENT EMERGENCY ACTION FLOOD PROOFING LAND-USE REGULATION FINANCIAL ADJUSTMENT CHOICE OF ADJUSTMENT
FLOOD ABATEMENT It is sometimes referred to as watershed (or catchmet) maagemet ad costitutes a attractive scietific procedure i which the flood problem is approached from first priciples ad actio is take at the poit upstream where the flood is geerated rather tha waitig to take actio dowstream at locatios where that flood would represet a potetial threat.
Flood abatemet thus subscribes to the basic maxim that prevetio is better tha cure. However, the flood abatemet approach is ofte hampered by a umber of factors.
FLOOD PROTECTION The costructio of embakmets (sometimes referred to as dikes or levees) ad floodwalls to cofie the floodwaters. The improvemet of river chaels to elarge their discharge capacity, for example, by straighteig, wideig or deepeig. The costructio of bypass ad diversio chaels to carry some of the excess floodwater away from the area to be protected. The costructio of reservoirs for the temporary storage of floodwater.
FLOOD DAMAGE ASSESSMENT Physical damage to buildigs ad their cotets, bridges, roads, railways, etc. Agricultural crops losses. Loss of icome due to iterruptio of busiess. Cost of flood fightig, ad the evacuatio, care ad rehabilitatio of flood victims.
Schematic Breakdow of Flood Damages FLOOD DAMAGES TANGIBLE INTANGIBLE e.g. axiety, ill-health DIRECT e.g. physical damage by flood water INDIRECT e.g. loss of productio, iterrupted traffic flow PRIMARY SECONDARY PRIMARY SECONDARY
FUTURE PROSPECTS IN FLOOD DISASTER RISK MANAGEMENT Floods have bee preseted as a global pheomeo affectig both rich ad poor, the prepared ad uprepared. They are a complex, iterdiscipliary problem-for some aspects satisfactory solutios have already bee advaced, but for others o likely aswers are as yet forthcomig. Ma s attempts to cotrol rivers have ofte had little or o success. I fact, may times his efforts have aggravated the situatio. The greatest atural disasters come as a result of igorace or, eve worse, half-kowledge.
Both log ad short data rus ted to be characterized by the variable quality of the data. There is cosiderable scope for improvig the form i which data are collected ad preseted. There is eed for the compilatio of clear ad useful iformatio o floods ad flood hazards Procedures which permit a accurate cotiuous accoutig of catchmet wetess, expressed perhaps i terms of soil moisture deficit or by direct satellite observatios of soil moisture status, are likely to play a major role i improved forecastig.
Flood forecastig will also beefit from direct satellite observatios of the areal extet of upstream floodig ad its chage with time. Oe of the most pressig task i flood maagemet is to sharpe the perceptio of the flood hazard ad the rage of possible resposes amog those most at risk. From repeated experieces it is obvious that more tha the mere presetatio of facts is required to mobilize the commuities for effective flood disaster risk maagemet. While floods may be atural occurreces, the flood hazard is largely ma-made ad as log as ma chooses to live i flood-proe areas disasters are boud to happe.
Moder skills iclude a kowledge of flood-formig processes, a uderstadig of probability theory, a acquaitace with ecoomic aalysis, a isight ito the social behavior of ma ad a awareess of the realities ad costraits of the political processes o regioal basis. It must be bore i mid that protectio from floods is oly a relative matter, ad that evetually ature demads its toll from those who occupy flood plais.
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