THE FLOOD
version
Rusi Marinov
1.0
What is a flood?
It is generally regarded that flooding takes place when the authorities say so,
then they ask for the evacuation of the island. Flooding takes place on a small
scale regularly, when the river can come up over the moorings on the high
tide on the full moon. (with a dog howling in the background.)
A flood is an overflow of an expanse of water that submerges land, a deluge.
In the sense of “flowing water”, the word may also be applied to the inflow of
the tide.
Flooding may result from the volume of water within a body of water, such
as a river or lake, exceeding the total capacity of its bounds, with the result
that some of the water flows or sits outside of the normal perimeter of the
body. It can also occur in rivers, when the strength of the river is so high it
flows right out of the river channel, particularly at corners or meanders.
The word comes from the Old English “flod”, a word common to Teutonic
languages (compare German Flut, Dutch vloed from the same root as is seen
in flow, float).
The term “The Flood”, capitalized, usually refers to the great Universal
Deluge described in Genesis and is treated at Deluge.
1.1 Pictures.
2.0.What types of floods are there?
There is often no sharp distinction between river floods, flash floods, alluvial
fan floods, ice-jam floods, and dam-break floods that occur due to structural
failures or overtopping of embankments during flood (or other such as
landsliding, rockfalling, etc.) events. Nevertheless, these types of floods are
widely recognised and helpful in considering not only the range of flood risk
but also appropriate emergency preparedness and responses.
In general, the river floods are caused either by rainfall of extra-tropical or
frontal character, as experienced in temperate latitudes, or by large tropical
atmospheric depressions with moisture-laden winds, moving from a maritime
environment onto and across a land mass. Rainfall in these events is generally
widespread and can be heavy. The level of flooding can be high, and is
influenced by topographic features.
2.1. Revering flooding.
Riverine flooding includes:
• overflow from river channel or river floods
• flash floods
• alluvial fan floods
• ice-jam floods
• dam-break floods
2.1.1. Overflow from river channel or river floods.
Overbank flooding of rivers and streams is the most common type of flood
event. River (riverine) flood plains (Fig. 1) range from narrow confined
channels in the steep valleys of hilly and mountainous areas, and wide, flat
areas in the plains and low-lying coastal regions. The amount of water in the
floodplain is a function of the size of the contributing watershed and
topographic characteristics such as watershed type and slope, and climatic
and land-use characteristics.
Consequently, the magnitude and extent of a river flood depends upon the
size of the catchment area of the river (contributing watershed), the
topography, soil conditions and vegetation, and the weather conditions
involved. Size of catchment area usually governs the character of flooding as
well as the type of meteorological event, or events, which are capable of
inducing extreme floods.
2.1.1.1. More information’s.
For instance, river flow on very large rivers (such as the Nile, the Danube or
the Rhine) is relatively slow to change in the downstream reaches (Fig. 3a);
floodwaters will generally be a combination of many rainfall events occurring
over a wide area, sometimes augmented by melted snow. In large river basins
flooding is usually seasonal and peak discharges can be reached and
maintained over days or weeks.
Flooding in large rivers usually results from large-scale weather systems that
generate prolonged rainfall over wide areas. These same weather systems
may cause flooding in hundreds of smaller basins that drain to major rivers.
Small rivers and streams are susceptible to flooding from more localized
weather systems that cause intense rainfall over small areas.
The principal characteristics of river floods are their relatively slow build-up,
which in river systems is usually seasonal.
However, the shape of the catchment area has a considerable effect on the
peak water discharge in a river or stream (Fig. 3). The rounder the area and
the more uniform routes the water takes to the point in question (Fig. 3b), the
more the water tends to arrive simultaneously, increasing the possibility of an
extreme flood peak (hydrograph B of Fig. 3c). As a rule, round and small
catchment areas, which are commonly found in the upper reaches of rivers
and in the mountains produce a quickly rising hydrograph after intense
(torrential) rainfall. Thus, the flood peak at a given location is in general very
pronounced.
In longer and wider catchments the run-off is spread better over time (Fig.
3a), as is mostly encountered in flat terrains at the lower reaches of rivers.
The hydrograph rises relatively slowly and then flattens out (hydrograph A of
Fig. 3c). The water arrives at a given point gradually, even if rainfall is
intense. The characteristics of a catchment area and its hydrograph, such as
hydrograph A of Fig. 3c, can also result in the land being submerged for a
long time.
However, if the rainstorm progresses over a long catchment area towards the
point in question in such a manner that it adds more and more water to the
flood peak, a situation can develop which is as precarious as the one seen in
the hydrograph B of Fig. 3c.
2.1.2. Flash floods.
"Flash flood" \s a term widely used by flood experts and the general
population. However, there is no single definition, and a clear means to
separate flash floods from the rest of the spectrum of riverine floods does not
exist. Floods of this type are particularly dangerous because of the
suddenness and speed with which they occur. They develop in a basin
following the occurrence of one or more previously mentioned storm types,
especially if the catchment slope is conductive to acceleration of run-off
rather than its attenuation.
Flash floods are events with very little time occurring between the start of
the flood and the peak discharge. They are often associated with a short time
between the storm incidence and the arrival of the flood wave, which is not
always the case; and are of short duration with relatively high peak discharge.
Flash floods are characterized by a rapid rise in water level, high velocity,
and large amounts of debris. They are capable of tearing out trees,
undermining buildings and bridges, and scouring new channels. Major factors
in flash flooding are the intensity and duration of rainfall and the steepness of
watershed and stream gradients. The amount of watershed vegetation, the
natural and artificial flood storage areas, and the configuration of the
streambed and floodplain are also important.
2.1.2.1. More information’s.
Flash floods are often associated with isolated and localised intense rainfall.
In some regions, severe and destructive flash floods occur very infrequently
in any one of a large number of small catchments within a given region.
Efficient surveillance, warning and protection against the hazard are therefore
difficult. In other regions, flash floods occur annually on the same river;
warning in these cases is more a matter of timeliness. Because the warning
time is invariably limited, the flash floods are now the main cause of weatherrelated deaths.
Flash floods may result from the failure of a dam or the sudden break-up of
an ice jam. Both can cause the release of a large volume of water in a short
period of time. Flash flooding in urban areas is an increasingly serious
problem due to removal of vegetation, paving and replacement of ground
cover by impermeable surfaces that increase runoff, and construction of
drainage systems that increase the speed of runoff.
2.1.2.2. Animations.
2.1.3. Alluvial fan floods.
Alluvial fans are deposits of rock and soil that have eroded from
mountainsides and accumulated on valley floors in a fan-shaped pattern. The
deposits are narrow and steep at the head of the fan, broadening as they
spread out onto the valley floor. As rain runs off steep valley walls, it gains
velocity, carrying large boulders and other debris. When the debris fills
channels on the fan, floodwaters spill out and cut new channels. The process
is then repeated, resulting in shifting channels and combined erosion and
flooding problems over a large area.
Alluvial fan floods can cause greater damage than typical riverine flooding
because of the high velocity of flow, the amount of debris carried, and the
broad area affected. Floodwaters typically move at velocities of 5 to 10
metres per second due to steep slopes and lack of vegetation.
Human activities often exacerbate flooding and erosion problems on alluvial
fans. Roads act as drainage channels, carrying high velocity flows to lower
portions of the fan, while fill, levelling, grading, and structures can alter
flows patterns.
2.1.3.1. Animation.
2.1.4. Ice – jam floods.
Flooding caused by ice jams is similar to flash flooding. Ice jam formation
causes a rapid rise of water at the jam and extending upstream. Failure or
release of the jam causes sudden flooding downstream.
The formation of ice jams depends on the weather and physical conditions in
river channels. Ice jams are most likely to occur where the channel slope
naturally decreases, where culverts freeze solid, at headwaters of reservoirs,
at natural channel constructions such as bends and bridges, and long shallows
where channels may freeze solid.
Ice jams floods can occur during fall freeze-up from the formation of frazil
ice, during midwinter periods when stream channels freeze solid forming
anchor ice, and during spring break-up when rising water levels from
snowmelt or rainfall break existing ice cover into large floating masses that
lodge at bridges and other constructions. Damage from ice jam flooding
usually exceeds that caused by open water flooding. Flood elevations are
usually higher than predicted for free-flow conditions and water levels may
change rapidly. The force of ice impacting buildings and other structures can
cause additional physical damage.
2.1.4.1. Animation.
2.1.5. Dam – break floods.
Dam failures can occur as a result of structural failures, such as progressive
erosion of an embankment or overtopping and breaching by a severe flood.
Earthquakes may weaken dams. Disastrous floods caused by dam failures,
although not in the category of natural hazards, have caused great loss of life
and property damage, primarily due to their unexpected nature and high
velocity floodwater.
2.1.5.1. Animation.
2.2 Local drainage or high groundwater levels.
Local heavy precipitation may produce flooding in areas other than
delineated floodplains or along recognizable drainage channels. If local
conditions cannot accommodate intense precipitation through a combination
of infiltration and surface runoff, water may accumulate and cause flooding
problems. During winter and spring, frozen ground and accumulations of
snow may contribute to inadequate drainage and localized ponding. Flooding
problems of this nature generally occur in areas with flat gradients, and
generally increase with urbanisation which speeds the accumulation of
floodwaters because of impervious areas. Shallow sheet flooding may result
unless channels have been improved to account for increased flows.
High groundwater levels may be of concern and can cause problems even
where there is no surface flooding. Basements are susceptible to high
groundwater levels. Seasonally high groundwater is common in many areas,
while in others high groundwater occurs only after long periods of aboveaverage precipitation.
2.2.1. Animation.
2.3. Fluctuating lake levels.
Water levels in lakes can fluctuate on a short-term, seasonal basis, or on a
long-term basis over periods of months or years. Heavy seasonal rainfall can
cause high lake levels for short periods of time, and snowmelt can result in
higher spring levels. Long-term fluctuations are a less-recognised
phenomenon that can cause high water and subsequent flooding problems
lasting for years or even decades.
While all lakes may experience fluctuations, water levels tend to vary the
most in lakes that are completely landlocked or have inadequate outlets for
maintaining a balance between inflow and outflow. These lakes, commonly
referred to as closed-basin lakes, are particularly susceptible to dramatic
fluctuations in water levels over long periods of time, as much as 1 to 3
metres.
Fluctuations of lake water levels over a short period of time, initiated by local
atmospheric changes, tidal currents, or earthquakes, are known as "seiches".
These, free or standing wave oscillations of the surface of water in an
enclosed basin are similar to water sloshing in a bathtub.
2.3.1. Animation.
2.4.Coastal flooding.
Devastating floods can occur as a result of extreme wind storms (typhoons,
hurricanes or tropical cyclones). The Indian sub-continent (Bay of Bengal),
and countries in Asia and the Pacific are all typically subject to such events.
Catastrophic flooding from rainfall is often aggravated by wind-induced
surge and low atmospheric pressure along a coastline
Storm surges occur when the water level of a tidally influenced body of water
increases above the normal astronomical high tide. Storm surges commonly
occur with coastal storms caused by massive low-pressure systems with
cyclonic flows that are typical of tropical cyclones, northeasters, and severe
winterstorms. Other factors influencing storm surge intensity are:
• wind velocity
• storm surge height
• coastal shape
• storm centre velocity
• nature of coast
• previous storm damage
• human activity
2.4.1. More information’s.
Storm surges generated by coastal storms are controlled by the following four
factors:
• The more intense storms have higher wind speeds which drive greater
amounts of water across the shallow continental shelf, thereby increasing the
volume and elevation of water pushed up against the coast. In areas with mild
slopes and shallow depths, the resulting flooding can reach great heights.
• The low barometric pressure experienced during coastal storms can cause
the water surface to rise, increasing the height of storm surges.
• Storms landfalling during peak astronomical tides have higher surge heights
and more extensive flood inundation limits.
• Coastal shoreline configurations with concave features or narrowing bays
create a resonance within the area as a result of the winds forcing in water,
elevating the surface of the water higher than experienced along adjacent
areas of open coast.
The other causes of coastal flooding are tsunamis, the large seismic sea
waves, impulsively generated by shallow-focus earthquakes.
2.5. Estuarine floods.
Commonly caused by a combination of sea tidal surges caused by stormforce winds.
Storm surge is an offshore rise of water associated with a low pressure
weather system, typically a tropical cyclone. Storm surge is caused primarily
by high winds pushing on the ocean's surface. The wind causes the water to
pile up higher than the ordinary sea level. Low pressure at the center of a
weather system also has a small secondary effect, as can the bathymetry of
the body of water. It is this combined effect of low pressure and persistent
wind over a shallow water body which is the most common cause of storm
surge flooding problems. The term "storm surge" in casual (non-scientific)
use is storm tide; that is, it refers to the rise of water associated with the
storm, plus tide, wave run-up, and freshwater flooding. When referencing
storm surge height, it is important to clarify the usage, as well as the
reference point. National Hurricane Center tropical cyclone reports reference
storm surge as water height above predicted astronomical tide level, and
storm tide as water height above NGVD-29. Most casualties during a tropical
cyclone occur during the storm surge.
2.6. Catastrophic floods.
Caused by a significant and unexpected event e.g. dam breakage, or as a
result of another hazard (e.g. earthquake or volcanic eruption).
For example: Tropical Storm Alberto, the famous 1994 storm, produced
heavy flooding across Georgia, Alabama and northwest Florida and created
between 400-600 million dollars worth of damage in the Southeastern US in
1994 United States Dollars.
2.7. Regional floods.
Floods can occur if water accumulates across an impermeable surface (e.g.
from rainfall) and cannot rapidly dissipate (i.e. gentle orientation or low
evaporation). A series of storms moving over the same area. Dam-building
beavers can flood low-lying urban and rural areas, often causing significant
damage.
Regional floods are caused by snow melt, and annual phenomena like the
Malaysian monsoons and the yearly Nile River overflow. The storms
overload the rivers. The floods can happen faster and be more serious if the
ground is frozen or already saturated with water.
2.8. Storm Surge Floods.
Most casualties during a tropical cyclone occur during the storm surge.
In areas where there is a significant difference between low tide and high
tide, storm surges are particularly damaging when they occur at the time of a
high tide. In these cases, this increases the difficulty of predicting the
magnitude of a storm surge since it requires weather forecasts to be accurate
to within a few hours. Storm surges can be produced by extra tropical
cyclones, such as the "Halloween Storm" of 1991 and the Storm of the
Century (1993), but the most extreme storm surge events occur as a result of
tropical cyclones. Factors that determine the surge heights for landfalling
tropical cyclones include the speed, intensity, size of the radius of maximum
winds (RMW), radius of the wind fields, angle of the track relative to the
coastline, the physical characteristics of the coastline and the bathymetry of
the water offshore. The SLOSH (Sea, Lake, and Overland Surges from
Hurricanes) model is used to simulate surge from tropical cyclones.
The Galveston Hurricane of 1900, a Category 4 hurricane that struck
Galveston, Texas, drove a devastating surge ashore; between 6,000 and
12,000 lives were lost, making it the deadliest natural disaster ever to strike
the United States. The second deadliest natural disaster in the United States
was the storm surge from Lake Okeechobee in the 1928 Okeechobee
Hurricane which swept across the Florida peninsula during the night of
September 16. The lake surged over its southern bank, virtually wiping out
the settlements on its south shore. The estimated death toll was over 2,500;
many of the bodies were never recovered. Only two years earlier, a storm
surge from the Great Miami Hurricane of September 1926 broke through the
small earthen dike rimming the lake's western shore, killing 150 people at
Moore Haven, Florida
2.9. Other types floods.
Slow-Onset Floods:Slow- Onset Floods usually last for a relatively longer
period, it may last for one or more weeks, or even months. As this kind of
flood last for a long period, it can lead to lose of stock, damage to agricultural
products, roads and rail links.
Rapid-Onset Floods:Rapid- Onset Floods last for a relatively shorter period,
they usually last for one or two days only. Although this kind of flood lasts
for a shorter period, it can cause more damages and pose a greater risk to life
and property as people usually have less time to take preventative action
during rapid-onset floods.
Coastal flooding: Coastal flooding may occur due to tidal surges and flash
flooding.
Dam Failure: Dam failures are potentially the worst flood events. When a
dam fails, a gigantic quantity of water is suddenly let loose downstream,
destroying anything in its path.
Arroyos Floods. A arroyo is river which is normally dry. When there are
storms approaching these areas, fast-moving river will normally form along
the gully and cause damages
Urban Floods-In most of the urban area, roads are usually paved. With heavy
rain, the large amount of rain water cannot be absorbed into the ground and
leads to urban floods.
3.0.Why do the flood occur?
Flooding occurs most commonly from heavy rainfall when natural
watercourses do not have the capacity to convey excess water. However,
floods are not always caused by heavy rainfall. They can result from other
phenomenon, particularly in coastal areas where inundation can be caused by
a storm surge associated with a tropical cyclone, a tsunami or a high tide
coinciding with higher than normal river levels. Dam failure, triggered for
example by an earthquake, will result in flooding of the downstream area,
even in dry weather conditions.
In general, the factors which influence whether a flood will occur include:
 volume, spatial distribution, intensity and duration of rainfall over a
catchments;





the capacity of the watercourse or stream network to convey runoff;
catchments and weather conditions prior to a rainfall event;
ground cover;
topography; and
tidal influences.
Flooding occurs in both natural and developed watersheds. When the rate of
rainfall or snowmelt exceeds the rate of infiltration to the ground, the excess
water, called runoff, moves across the ground surface toward the lowest
section of the watershed. As the surface runoff enters stream channels, stream
levels increase. If the rate of runoff is high enough, water in the stream
overflows the banks and flooding occurs. This area of over-bank flow is
called the flood plain. All natural watersheds have flood plains. Structures
located in these flood plains are subject to damage. In a natural watershed,
flooding can be affected by ice jams, the accumulation of debris at channel
constrictions, and even the dam-building activity of beavers.
3.1.More information’s.
Human activity has profound impacts on flooding. The two major activities
which impact flooding are land use change and the building of flood control
structures.
Land Use Change- Hundreds of years ago, the Delaware River Basin (USA)
was covered by forests. This maximized the infiltration of rainfall and slowed
the movement of runoff. As the land was cleared for agriculture, infiltration
rates were reduced and runoff rates increased. The increase in runoff rates
widened flood plains and stream channels in many of the basin's watersheds.
With gradual urbanization and the increasing use of asphalt and concrete
paving, in addition to densely spaced buildings, infiltration rates were further
reduced with corresponding increases in runoff rates. Because of these land
use changes, flood flow rates in many areas are much higher than they would
naturally be for a given rain storm. Although some land that was formerly in
agricultural use has been reforested, the runoff reduction benefits have been
offset in many areas by continued urbanization.
The transportation network associated with land use change also affects
flooding. In addition to the impacts of impervious paved surfaces, bridges
and culverts usually constrict stream channels and flood plains. This
aggravates upstream flooding, especially when the constrictions become
clogged with ice or debris.
Flood Control Structures- The purpose of flood control structures is to
physically constrain or to convey flood waters. Flood control structures
include dams, levees, lined stream channels, and storm sewers. Dams and
levees have been used for centuries to open flood plains to agriculture and
settlement, and in the case of dams, to detain flood waters for gradual release
or for use for water supply, recreation, and the generation of hydroelectricpower. Dams and levees are highly effective in flood loss reduction.
Though effective, one drawback to the use of dams and levees for flood loss
reduction is that they are very expensive. Secondly, local cost sharing
requirements and environmental issues have slowed construction of new
facilities in recent years. Flood control dams and levees are not necessary
where there is no flood plain development.
3.2.Where do the floods occur.
Riverine flooding occurs in relatively low-lying areas adjacent to streams
and rivers. In the extensive flat inland regions of Australia, floods may spread
over thousands of square kilometers and last several weeks, with flood
warnings sometimes issued months in advance. In the mountain and coastal
regions of Australia flooding can happen rapidly with a warning of only a
few hours in some cases.
The Great Dividing Range which extends along the length of eastern
Australia provides a natural separation between the longer and slower
westerly flowing rivers and the shorter, faster easterly flowing coastal rivers.
In some cases natural blockages at river mouths, including storm surge and
high tides, also may cause localized flooding of estuaries and coastal lake
systems.
Flash floods can occur almost anywhere there is a relatively short intense
burst of rainfall such as during a thunderstorm. As a result of these events the
drainage system has insufficient capacity or time to cope with the downpour.
Although flash floods are generally localized, they pose a significant threat
because of their unpredictability and normally short duration.
3.2.1.More information’s
A flood typically occurs when a river (or other body of water) overflows its
banks. As you can read Physical Geography: The Global Environment, third
edition, annual floods can even be a normal part of a floodplain’s
development. These floods deposit sediments that build a river’s natural
levees, broad ridges that run along both sides of the channel. Figure F-3
shows the relationship between floods and natural levee development. As the
river spills out of its channel, the coarsest material it is carrying is depostied
closest to the overflow, hence along the levees. When the river contracts after
the flood, it stays within its self-generated levees.
Image from Physical Geography However, not all floods are so regular and
productive. Infrequently—perhaps once in a century—a river may experience
a flood of such magnitude that its floodplain is greatly modified. Water up to
several meters deep may inundate the entire floodplain, destroying
submerged levees, eroding bluffs, and disrupting the entire system. These
sorts of floods have cost millions of lives in the densely populated floodplains
of Asia’s major rivers. They also occur in the Mississippi Basin of the central
United States, where the damage, too, can be enormous. No reinforcement of
natural levees or construction of artificial levees can withstand the impact of
such a powerful “100-year” flood.
4.1.Number of the floods in the world.
Floods are among the most powerful forces on earth. Human societies
worldwide have lived and died with floods from the very beginning,
spawning a prominent role for floods within legends, religions, and history.
Inspired by such accounts, geologists, hydrologists, and historians have
studied the role of floods on humanity and its supporting ecosystems,
resulting in new appreciation for the many-faceted role of floods in shaping
our world. Part of this appreciation stems from ongoing analysis of long-term
streamflow measurements, such as those recorded by the U.S. Geological
Survey’s (USGS) streamflow gaging network. But the recognition of the
important role of flooding in shaping our cultural and physical landscape also
owes to increased understanding of the variety of mechanisms that cause
floods and how the types and magnitudes of floods can vary with time and
space. The USGS has contributed to this understanding through more than a
century of diverse research activities on many aspects of floods, including
their causes, effects, and hazards. This Circular summarizes a facet of this
research by describing the causes and magnitudes of the world’s largest
floods, including those measured and described by modern methods in
historic times, as well as floods of prehistoric times, for which the only
records are those left by the floods themselves.
Largest meteorologic floods from river basins larger than about 500,000 square kilometers.
CountryBasin area (103 km2)b StationStation area(10
Station
3 km
latitude
2) Station
(degrees)
longitude Date
(degrees)
Peak discharge(m
Flood
3/s) type
Amazon
Nile
Congo
Mississippic
Amur
Parana
Yenisey
Ob-Irtysh
Lena
Niger
Zambezi
1
2
3
4
5
6
7
8
9
10
11
Brazil
Egypt
Zaire
USA
Russia
Argentina
Russia
Russia
Russia
Niger
Mozambique
5,854
3,826
3,699
3,203
2,903
2,661
2,582
2,570
2,418
2,240
1,989
Obidos
Aswan
Brazzaville B.
Arkansas City
Komsomolsk
Corrientes
Yeniseysk
Salekhard
Kasur
Lokoja
Tete
4,640
1,500
3,475
2,928
1,730
1,950
1,400
2,430
2,430
1,080
940
1.9S
24.1N
4.3S
33.6N
50.6N
27.5S
58.5N
66.6N
70.7N
7.8N
16.2S
55.5W
32.9E
15.4E
91.2W
138.1E
58.9W
92.1E
66.5E
127.7E
6.8E
33.6E
370,000
13,200
76,900
70,000
38,900
43,070
57,400
44,800
189,000
27,140
17,000
June 1953
Sept. 25, 1878
Dec. 27, 1961
May 1927
Sept. 20, 1959
June 5, 1905
May 18, 1937
Aug. 10, 1979
June 8, 1967
Feb. 1, 1970
May 11, 1905
Rainf
Rainf
Rainf
Rainf
Rainf
Rainf
Snow
Snow
Snow
Rainf
Rainf
Yangtze
12
Mackenzie 13
Chari
14
Volga
15
St. Lawrence16
Indus
17
Syr Darya 18
Orinoco
19
Murray
20
Ganges
21
Shatt al Arab22
Orange
23
Huanghe
24
Yukon
25
Senegal
26
Coloradoc 27
Rio Grandec 28
Danube
29
Mekong
30
Tocantins 31
Columbiac 32
Darling
33
Brahmaputrad34
São Francisco35
Amu Darya 36
Dnieper
37
China
Canada
Chad
Russia
Canada
Pakistan
Kazakhstan
Venezuela
Australia
Bangladesh
Iraq
South Africa
China
USA
Senegal
USA
USA
Romania
Vietnam
Brazil
USA
Australia
Bangladesh
Brazil
Kazakhstan
Ukraine
4.2. More information’s.
4.3. Animation.
1,794
1,713
1,572
1,463
1,267
1,143
1,070
1,039
1,032
976
967
944
894
852
847
808
805
788
774
769
724
650
650
615
612
509
Yichang
1,010
Norman Wells 1,570
N'Djamena
600
Volgograd
1,350
La Salle
960
Kotri
945
Tyumen’-Aryk 219
Puente Angostura836
Morgan
1,000
Hardings Bridge 950
Hit(Euphrates) 264
Buchuberg
343
Shanxian
688
Pilot Station
831
Bakel
218
Yuma
629
Roma
431
Orsova
575
Kratie
646
Itupiranga
728
The Dalles
614
Menindee
570
Bahadurabad
636
Traipu
623
Chatly
450
Kiev
328
30.7N
65.3N
12.1N
48.5N
45.4N
25.3N
44.1N
8.1N
34.0S
23.1N
34.0N
29.0S
34.8N
61.9N
14.9N
32.7N
26.4N
44.7N
12.5N
5.1S
45.6N
32.4S
25.2N
9.6S
42.3N
50.5N
111.2E
126.9W
15.0E
44.7E
73.6W
68.3E
67.0E
64.4W
139.7E
89.0E
42.8E
22.2E
111.2E
162.9W
12.5W
114.6W
99.0W
22.4E
106.0E
49.4W
121.2W
142.5E
89.7E
37.0W
59.7E
30.5E
110,000
30,300
5,160
51,900
14,870
33,280
2,730
98,120
3,940
74,060
7,366
16,230
36,000
30,300
9,340
7,080
17,850
15,900
66,700
38,780
35,100
2,840
81,000
15,890
6,900
23,100
July 20, 1870
May 25, 1975
Nov. 9, 1961
May 27, 1926
May 13, 1943
1976
June 30, 1934
Mar. 6, 1905
Sept. 5, 1956
Aug. 21, 1973
May 13, 1969
1843
Jan. 17, 1905
May 27, 1991
Sept. 15, 1906
Jan. 22, 1916
1865
April 17, 1895
Sept. 3, 1939
April 2, 1974
June 6, 1894
June 1890
Aug. 6, 1974
April 1, 1960
July 27, 1958
May 2, 1931
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Snow
Rainf
Snow
Snow
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Rain/
Rainf
Rainf
Rain/
Rain/
Rainf
Rainf
Snow
Rainf
Rainf
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Rainf
Snow
Rainf
Rain/
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Rain/
Snow
4.4.What were the largest floods in the world?
4.1.1. Pictures.
4.2. What were the largest floods in Europe?
London is protected from flooding by a huge mechanical barrier across the
River Thames, which is raised when the water level reaches a certain point
(see Thames Barrier).
Venice has a similar arrangement, although it is already unable to cope with
very high tides. The defenses of both London and Venice will be rendered
inadequate if sea levels continue to rise.
The largest and most elaborate flood defenses can be found in the
Netherlands, where they are referred to as Delta Works with the
Oosterschelde dam as its crowning achievement. These works were built in
response to the North Sea flood of 1953 of the southwestern part of the
Netherlands. The Dutch had already built one of the world’s largest dams in
the north of the country: the Afsluitdijk (closing occurred in 1932).
Flood blocking the road in JerusalemCurrently the Saint Petersburg Flood
Prevention Facility Complex is to be finished by 2008, in Russia, to protect
Saint Petersburg from storm surges. It also has a main traffic function, as it
completes a ring road around Saint Petersburg. Eleven dams extend for 25.4
kilometres and stand eight metres above water level.
The New Orleans Metropolitan Area, 35% of which sits below sea level, is
protected by hundreds of miles of levees and flood gates. This system failed
catastrophically during Hurricane Katrina in the City Proper and in eastern
sections of the Metro Area, resulting in the inundation of approximately 50%
of the Metropolitan area, ranging from a few inches to twenty feet in coastal
communities.
In an act of successful flood prevention, the Federal Government of the
United States offered to buy out flood-prone properties in the United States in
order to prevent repeated disasters after the 1993 flood across the Midwest.
Several communities accepted and the government, in partnership with the
state, bought 25,000 properties which they converted into wetlands. These
wetlands act as a sponge in storms and in 1995, when the floods returned, the
government didn’t have to expend resources in those areas.
Autumn Mediterranean flooding in Alicante (Spain), 1997.In western
countries, rivers prone to floods are often carefully managed. Defences such
as levees, bunds, reservoirs, and weirs are used to prevent rivers from
bursting their banks. Coastal flooding has been addressed in Europe with
coastal defences, such as sea walls and beach nourishment.
4.2.1.More information’s
Remembering the misery and destruction caused by the 1910 Great Flood of
Paris, the French government built a series of reservoirs called Les Grands
Lacs de Seine (or Great Lakes) which helps remove pressure from the Seine
during floods, especially the regular winter flooding.[6]
London is protected from flooding by a huge mechanical barrier across the
River Thames, which is raised when the water level reaches a certain point
(see Thames Barrier).
Venice has a similar arrangement, although it is already unable to cope with
very high tides. The defences of both London and Venice would be rendered
inadequate if sea levels were to rise.
The River Berounka, Czech Republic, burst its banks in the 2002 European
floods and houses in the village of Hlásná Třebaň, Beroun District, were
inundated.
The largest and most elaborate flood defences can be found in the
Netherlands, where they are referred to as Delta Works with the
Oosterschelde dam as its crowning achievement. These works were built in
response to the North Sea flood of 1953 of the southwestern part of the
Netherlands. The Dutch had already built one of the world's largest dams in
the north of the country: the Afsluitdijk (closing occurred in 1932).
Currently the Saint Petersburg Flood Prevention Facility Complex is to be
finished by 2008, in Russia, to protect Saint Petersburg from storm surges. It
also has a main traffic function, as it completes a ring road around Saint
Petersburg. Eleven dams extend for 25.4 kilometres and stand eight metres
above water level.
In Austria, flooding for over 150 years, has been controlled by various
actions of the Vienna Danube regulation, with dredging of the main Danube
during 1870-75, and creation of the New Danube from 1972-1988.
4.2.1. Pictures.
5.0 What could be the consequences of the floods?
5.1.Typical effects.
Floods and other natural disasters often are followed by rumors of
plausible epidemics such as typhoid or cholera. The potential for such rumors
delegitimizes the need for valid and systematically collected data and the
importance of basic public health surveillance in these settings.
In terms of municipal ramifications, communities can be greatly set back
by floods in both a developmental sense and on an economic level.
First, should water supplies be infected or breached, a major overhaul is
necessary for the water providing utility, resulting in significant corporate
losses. Related is the plausible taintedness of food products that would be
used to feed the displaced. If food supplies are damaged, then a municipality
is forced to procure new food stores to disseminate to it‘s citizens, resulting
in wasted time and deaths; if electric power is cut or limited by flood waters,
then specifically preserved food is necessary.
Waste and sanitation is a primary concern for municipalities in the wake of a
flood, considering that those interrelated entities bear tremendous public
health implications. Should fecal matter and waste products seep into primary
water transplant channels along with the floodwater, the use of all water pipes
would be immediately censured, and citizens would be literally stranded
insofar as their ability to procure necessary food products. Lastly, such
preventative measures should include injury prevention. Flood removal
(through pump mechanisms) and mosquito spraying all would cost extensive
amounts of money.
5.1.1.Primary effects.
Physical damage: Can range anywhere from bridges, cars, buildings, sewer
systems, roadways, canals and any other type of structure.
Casualties: People and livestock die due to drowning. It can also lead to
epidemics and diseases.
5.1.2.Secondary effects.
Water supplies: Contamination of water. Clean drinking water becomes
scarce.
Diseases: Unhygienic conditions. Spread of water-borne diseases
Crops and food supplies: Shortage of food crops can be caused due to loss of
entire harvest.
Trees: Non-tolerant species can die from suffocation.
Tertiary/long-term effects
Economic: Economic hardship, due to: temporary decline in tourism,
rebuilding costs, food shortage leading to price increase etc.
Flooding accounts for an estimated 40% of all natural disasters. Flash
flooding is the leading cause of weather-related mortality in the world, caused
through sudden, unexpected and significant rainfall or storm system
advancements.
Social. The social impact of floods primarily encompasses damage to homes
and displacement of the occupants that may, in turn, facilitate the diffusion of
an virulent strain of bacteria because of cramped and crowded living
conditions and less than adequate personal hygiene. Additionally, stressrelated mental health or substance-abuse problems may be associated with
flood disasters. Found to be a significant redevelopment issue after floods in
Europe and the United States, Post Traumatic Stress Disorder, a
psychological problem developed during the course and directly after a
dramatic event like a massive flood, greatly impedes an afflicted individual’s
desire to better himself and his community while impairing his judgment. In
terms of disease spreading, the environmental consequences of flooding can
directly affect public health measures. For example, water sources can
become contaminated with fecal material or toxic chemicals, water or sewer
systems can be disrupted, dangerous substances can be released into the water
supply (i.e. propane from damaged storage tanks), and solid-waste collection
and disposal can be spilled. In addition, flooding can result in vector borneassociated problems, including stark increases in mosquito populations that,
under judicious circumstances, increase the risk for some mosquito borne
infectious diseases like malaria and encephalitis.
5.1.3. Benefits of flooding.
There are many disruptive effects of flooding on human settlements
and economic activities. However, flooding can bring benefits, such
as making soil more fertile and providing nutrients in which it is
deficient. Periodic flooding was essential to the well-being of ancient
communities along the Tigris-Euphrates Rivers, the Nile River, the
Indus River, the Ganges and the Yellow River, among others. The
viability for hydrological based renewable sources of energy is
higher in flood prone regions.
5.2. Human loss;
Clean-up activities following floods often pose hazards to workers
and volunteers involved in the effort. Potential dangers include
electrical hazards, carbon monoxide exposure, musculoskeletal
hazards, heat or cold stress, motor vehicle-related dangers, fire,
drowning, and exposure to hazardous materials. Because flooded
disaster sites are unstable, clean-up workers might encounter sharp
jagged debris, biological hazards in the flood water, exposed
electrical lines, blood or other body fluids, and animal and human
remains. In planning for and reacting to flood disasters, managers
provide workers with hard hats, goggles, heavy work gloves, life
jackets, and watertight boots with steel toes and insoles.
5.3. Socio – economic;
5.4. Environmental;
5.5. Cultural heritage;
5.6. Others.
6.0.Can the causes of the floods be influenced by human behavior?
Flooding is defined as the accumulation of water within a water body and the
overflow of excess water onto adjacent floodplain lands. The floodplain is the
land adjoining the channel of a river (Fig. 2), stream, ocean, lake, or other
watercourse or water body that is susceptible to flooding.
Riverine floodplain and causes of flooding
Fig.1
Flooding is the most common environmental hazard. It regularly claims over
20,000 lives per year and adversely affects around 75 million people
worldwide. The reason lies in the widespread geographical distribution of
river flood plains and low-lying coasts, together with their long-standing
attractions for human settlement.
Several types of flood hazards confront the
physical planner, urban planner and
emergency manager:
• riverine flooding
• fluctuating lake levels
• local drainage or high groundwater levels
•
coastal
flooding
Fig. 2
(or inundation) including storm surges and tsunamis
The appearance of flood hazard is dominantly limited to the prevailing
weather system and geomorphological and topographical features of a given
area.
Inland flooding, as distinct from coastal flooding, is generally caused by the
overflow of watercourses as a result of intense rainfall or of a reduction in
waterway area by landslide or debris damming (which themselves may be
triggered by natural events such as earthquakes).
Coastal flooding can, in addition, be caused by extreme winds leading to
storm surges, by off-shore earthquake induced tidal waves (known as
tsunamis) or the subsidence of coastal land. Human manipulation of
watersheds, drainage basins, floodplains and the effects of deforestation, soil
erosion, silt carriage have increased volume and speed of runoff.
7.0. Can the consequences of the floods be influenced by human behavior?
In the last decades, Europe suffered a number of major floods, causing
fatalities,displacement of people, great economic loss and large impact on
nature. Since floods are naturalclimate driven processes, they have always
existed and will always exist. However, apart from their possible negative
impact, the beneficial effects of floods for society should also be remembered
and appropriate flood risk management can reduce the risks and damages
resulting from flooding. They are an inseparable part of the water cycle and
they supply floodplains with sediment and nutrients, which was the main
reason for early settlement in and development of floodplains. Both natural
characteristics and human interventions and activities in river basins
influence the amplitude, frequency, duration and impact of floods. In many
regions, climate change seems to increase the probability of flooding, while
human behaviour often reduces the resilience of the land and water resources
in the system. Floodplains are attractive for human settlements in highly
populated areas because of their economic potential. The floodplains are
often fertile agricultural areas and the rivers provide excellent transport
routes. But the ongoing occupation of the flood plains has increased the flood
risk. In addition, the increasing investments in traditional flood management
options like storing runoff, increasing the river’s capacity and separating river
and population by dikes, have affected the hydrological, ecological, economic
and social functioning in the river basin. Because traditional flood control is
essentially problem driven, the effect of interventions on other areas in the
river basin (upstream or downstream) or on other components of the water
system (land use, drinking water services, ecological services) have largely
been neglected. In addition, the construction of “visible” structural flood
protection measures has reduced the public awareness of flood risks.
Considering the benefits of human settlement near rivers and the threats and
costs of floods, an approach is needed that supports maximizing these
benefits and minimizes loss of life and capital. The approach therefore needs
to integrate land and water resources and reduce the vulnerability to floods,
recognizing the dynamics of the system as a whole.
8..0. Can the floods be predicted?
New World Meteorology System has possibility to predict all types of the
floods.Monitoring and control systems of the water.GPS and satellite pictures
in real time.
Floods can be such devastating disasters that anyone can be affected at
almost any time. As we have seen, when water falls on the surface of the
Earth, it has to go somewhere. In order to reduce the risk due to floods, three
main approaches are taken to flood prediction. Statistical studies can be
undertaken to attempt to determine the probability and frequency of high
discharges of streams that cause flooding. Floods can be modeled and maps
can be made to determine the extent of possible flooding when it occurs in
the future. And, since the main causes of flooding are abnormal amounts of
rainfall and sudden thawing of snow or ice, storms and snow levels can be
monitored to provide short-term flood prediction.
Frequency of Flooding
In your homework exercise you will see how flood frequencies can be
determined for any given stream if data is available for discharge of the
stream over an extended period of time. Such data allows statistical analysis
to determine how often a given discharge or stage of a river is expected.
From this analysis a recurrence interval can be determined and a probability
calculated for the likelihood of a given discharge in the stream for any year.
The data needed to perform this analysis are the yearly maximum discharge
of a stream from one gaging station over a long enough period of time.
In order to determine the recurrence interval, the yearly discharge values are
first ranked. Each discharge is associated with a rank, m, with m = 1 given to
the maximum discharge over the years of record, m = 2 given to the second
highest discharge, m = 3 given to the third highest discharge, etc.
The smallest discharge will receive a rank equal to the number of years over
which there is a record, n. Thus, the discharge with the smallest value will
have m = n.
The number of years of record, n, and the rank for each peak discharge are
then used to calculate recurrence interval, R by the following equation, called
the Weibull equation:
R = (n+1)/m
9.0. Is there any way to prevent the floods?
Responsibilities of:
Regions;
Countries;
Municipalities;
The European parliament and the Council of the European Union,
Having regard to the Treaty establishing the
European Community, and in particular Article 175(1) thereof Whereas:
(1) Floods have the potential to cause fatalities,
displacement of people and damage to the environment, to severely
compromise economic development and to undermine the economic
activities of the Community.
(2) Floods are natural phenomena which cannot
be prevented. However, some human activities (such as increasing human
settlements and economic assets in floodplains and the reduction of the
natural water retention by land use) and climate change contribute to an
increase in the likelihood and adverse impacts of flood events.
(3) It is feasible and desirable to reduce the risk of
adverse consequences, especially for human health and life, the
environment, cultural heritage, economic activity and infrastructure
associated with floods. However, measures to reduce these risks should, as
far as possible, be coordinated throughout a river basin if they are to be
effective.
(4) Directive 2000/60/EC of the European
Parliament and of the Council of 23 October 2000 establishing a
framework for Community action in the field of water policy [3] requires
river basin management plans to be developed for each river basin district
in order to achieve good ecological and chemical status, and it will
contribute to mitigating the effects of floods. However, reducing the risk
of floods is not one of the principal objectives of that Directive, nor does it
take into account the future changes in the risk of flooding as a result of
climate change.
(5) The Commission Communication of 12 July
2004 to the European Parliament, the Council, the European Economic
and Social Committee and the Committee of the Regions "Flood risk
management — Flood prevention, protection and mitigation" sets out its
analysis and approach to managing flood risks at Community level, and
states that concerted and coordinated action at Community level would
bring considerable added value and improve the overall level of flood
protection.
(6) Effective flood prevention and mitigation
requires, in addition to coordination between Member States, cooperation
with third countries. This is in line with Directive 2000/60/EC and
international principles of flood risk management as developed notably
under the United Nations Convention on the protection and use of
transboundary water courses and international lakes, approved by Council
Decision 95/308/EC [4], and any succeeding agreements on its application.
(7) Council Decision 2001/792/EC, Euratom of 23
October 2001 establishing a Community mechanism to facilitate
reinforced cooperation in civil protection assistance interventions [5]
mobilises support and assistance from Member States in the event of major
emergencies, including floods. Civil protection can provide adequate
response to affected populations and improve preparedness and resilience.
(8) Under Council Regulation (EC) No 2012/2002
of 11 November 2002 establishing the European Union Solidarity Fund [6]
it is possible to grant rapid financial assistance in the event of a major
disaster to help the people, natural zones, regions and countries concerned
to return to conditions that are as normal as possible. However the Fund
may only intervene for emergency operations, and not for the phases
preceding an emergency.
(9) In developing policies referring to water and
land uses Member States and the Community should consider the potential
impacts that such policies might have on flood risks and the management
of flood risks.
(10) Throughout the Community different types
of floods occur, such as river floods, flash floods, urban floods and floods
from the sea in coastal areas. The damage caused by flood events may also
vary across the countries and regions of the Community. Hence, objectives
regarding the management of flood risks should be determined by the
Member States themselves and should be based on local and regional
circumstances.
(11) Flood risks in certain areas within the
Community could be considered not to be significant, for example in
thinly populated or unpopulated areas or in areas with limited economic
assets or ecological value. In each river basin district or unit of
management the flood risks and need for further action — such as the
evaluation of flood mitigation potential — should be assessed.
(12) In order to have available an effective tool
for information, as well as a valuable basis for priority setting and further
technical, financial and political decisions regarding flood risk
management, it is necessary to provide for the establishing of flood hazard
maps and flood risk maps showing the potential adverse consequences
associated with different flood scenarios, including information on
potential sources of environmental pollution as a consequence of floods. In
this context, Member States should assess activities that have the effect of
increasing flood risks.
(13) With a view to avoiding and reducing the
adverse impacts of floods in the area concerned it is appropriate to provide
for flood risk management plans. The causes and consequences of flood
events vary across the countries and regions of the Community. Flood risk
management plans should therefore take into account the particular
characteristics of the areas they cover and provide for tailored solutions
according to the needs and priorities of those areas, whilst ensuring
relevant coordination within river basin districts and promoting the
achievement of environmental objectives laid down in Community
legislation. In particular, Member States should refrain from taking
measures or engaging in actions which significantly increase the risk of
flooding in other Member States, unless these measures have been
coordinated and an agreed solution has been found among the Member
States concerned.
(14) Flood risk management plans should focus
on prevention, protection and preparedness. With a view to giving rivers
more space, they should consider where possible the maintenance and/or
restoration of floodplains, as well as measures to prevent and reduce
damage to human health, the environment, cultural heritage and economic
activity. The elements of flood risk management plans should be
periodically reviewed and if necessary updated, taking into account the
likely impacts of climate change on the occurrence of floods.
(15) The solidarity principle is very important in
the context of flood risk management. In the light of it Member States
should be encouraged to seek a fair sharing of responsibilities, when
measures are jointly decided for the common benefit, as regards flood risk
management along water courses.
(16) To prevent duplication of work, Member
States should be entitled to use existing preliminary flood risk
assessments, flood hazard and risk maps and flood risk management plans
for the purposes of achieving the objectives and satisfying the
requirements of this Directive.
(17) Development of river basin management
plans under Directive 2000/60/EC and of flood risk management plans
under this Directive are elements of integrated river basin management.
The two processes should therefore use the mutual potential for common
synergies and benefits, having regard to the environmental objectives of
Directive 2000/60/EC, ensuring efficiency and wise use of resources while
recognising that the competent authorities and management units might be
different under this Directive and Directive 2000/60/EC.
(18) Member States should base their
assessments, maps and plans on appropriate "best practice" and "best
available technologies" not entailing excessive costs in the field of flood
risk management.
(19) In cases of multi-purpose use of bodies of
water for different forms of sustainable human activities (e.g. flood risk
management, ecology, inland navigation or hydropower) and the impacts
of such use on the bodies of water, Directive 2000/60/EC provides for a
clear and transparent process for addressing such uses and impacts,
including possible exemptions from the objectives of "good status" or of
"non-deterioration" in Article 4 thereof. Directive 2000/60/EC provides for
cost recovery in Article 9.
(20) The measures necessary for the
implementation of this Directive should be adopted in accordance with
Council Decision 1999/468/EC of 28 June 1999 laying down the
procedures for the exercise of implementing powers conferred on the
Commission.
(21) In particular, the Commission should be
empowered to adapt the Annex to scientific and technical progress. Since
those measures are of general scope and are designed to amend nonessential elements of this Directive, they must be adopted in accordance
with the regulatory procedure with scrutiny provided for in Article 5a of
Decision 1999/468/EC.
(22) This Directive respects the fundamental
rights and observes the principles recognised in particular by the Charter
of Fundamental Rights of the European Union. In particular, it seeks to
promote the integration into Community policies of a high level of
environmental protection in accordance with the principle of sustainable
development as laid down in Article 37 of the Charter of Fundamental
Rights of the European Union.
(23) Since the objective of this Directive, namely
the establishment of a framework for measures to reduce the risks of flood
damage, cannot be sufficiently achieved by the Member States and can by
reason of scale and effects of actions be better achieved at Community
level, the Community may adopt measures, in accordance with the
principle of subsidiarity as set out in Article 5 of the Treaty. In accordance
with the principle of proportionality, as set out in that Article, this
Directive does not go beyond what is necessary in order to achieve that
objective.
(24) In accordance with the principles of
proportionality and subsidiarity and the Protocol on the application of the
principles of subsidiarity and proportionality attached to the Treaty, and in
view of existing capabilities of Member States, considerable flexibility
should be left to the local and regional levels, in particular as regards
organisation and responsibility of authorities.
(25) In accordance with point 34 of the
Interinstitutional Agreement on better law-making, Member States are
encouraged to draw up, for themselves and in the interest of the
Community, their own tables illustrating, as far as possible, the correlation
between this Directive and the transposition measures.
10.0.Is there any way to mitigate flood consequences?
Make sure you are covered for flood damage. There are two types of flood
policies, one for the building and one for contents. Obviously, the first is the
more important, but both kinds are what you want if you can afford it. Have
good pictures of your house in pre-flood conditions.
If flooding occurs, get in touch with the insurance company as soon as
possible. The sooner you have an appointment for the company to inspect, the
sooner you can get money to start repairs. Mold damage, for instance, can
continue after the flood waters retreat. Start from the ground up, before a
flood. The right kind of floors can withstand flooding with only cleaning, and
possibly sanding and refinishing. Our 95-year-old wood floors looked
warped, but cleaning and re-varnishing made them as good as new. In the
"new" back (cerca 1920s), the vinyl tile came up as did the wood flooring
made from modular tile-like pieces we had installed. Carpeting, of course,
will be ruined. We had a contractor lay down wood and ceramic and
porcelain tile. If there is another flood, we can have a floor cleanup, replacing
drywall only. Next step is to think about your furniture. Solid wood furniture
can last with just a cleanup, like wooden floors. Although floods are initially
caused by nature, there are things that we humans can do to help prevent and
make sure that they are not devastating. If you are planning on building a new
home, you should take into to consideration not building on an active flood
plain. If there is a big storm or flood warning for some apparent reason, make
sure that all your storm drains are clear of leaves and any other substances
blocking the storm drain. If all else fails you should put down sandbags in
front of your house to prevent the water from coming in. Last but not least if
there is a possibility of flood from the river or a lake, it is possible to build up
the bank so that it will hold more water.
More information’s.
Veneer furniture will likely be lost, as will any upholstery that comes in
contact with flood waters. Anything electronic is likely to go. If you can
move this type of equipment to a higher level before a flood, if you have
warning, you may save some of it. Heavy pieces like refrigerators are likely
to be destroyed, however, in any case.
When doing your own cleaning, wear a mask. Mold spores can cause illness.
A chlorine bleach solution (10 parts water, one part bleach) is effective in
killing mold, as well as cheap.Our trees had been under salt water that was
laced with chemicals and sewage, and we thought they were probably lost.
We followed a neighbor's advice to water them deeply for half an hour per
day, and they came back, so you may be able to do this also.
10.0.Planning and Realization of the engineering works.
Although floods are initially caused by nature, there are things that we
humans can do to help prevent and make sure that they are not devastating. If
you are planning on building a new home, you should take into to
consideration not building on an active flood plain. If there is a big storm or
flood warning for some apparent reason, make sure that all your storm drains
are clear of leaves and any other substances blocking the storm drain. If all
else fails you should put down sandbags in front of your house to prevent the
water from coming in. Last but not least if there is a possibility of flood from
the river or a lake, it is possible to build up the bank so that it will hold more
water.
The goverment is attempting to reduce flooding by building damsand levees
in flood-prone areas. Levees are artificially raised riverbanks, and dams are
walls to block water. Levees can only go so high, and are easily overflowed
in large floods. Dams are very effective in preventing floods but change river
direction and take water away from some areas. In addition to controlling
floods, dams can provide hydroelectric power.
City Maintenance commissions continue to improve the drainage in towns,
especially in the roads. Road flooding is one of the first thing that happens in
most floods, and obliviously cuts off the major mode of transportation for
most people. Places below sea level need to be especially vigilant and
prepared for floods, because they will happen. people should be careful about
driving in floods because it is easy for your engine to flood and strand you on
a flooded highway. If you live in a low area you should make sure your house
is reasonably flood-proof, and no matter where you live you should have
flood insurance.
The goverment is attempting to reduce flooding by building dams and
levees in flood-prone areas. Levees are artificially raised riverbanks, and
dams are walls to block water. Levees can only go so high, and are easily
overflowed in large floods. Dams are very effective in preventing floods
but change river direction and take water away from some areas. In
addition to controlling floods, dams can provide hydroelectric power.
City Maintenance commissions continue to improve the drainage in
towns, especially in the roads. Road flooding is one of the first thing that
happens in most floods, and obliviously cuts off the major mode of
transportation for most people. Places below sea level need to be
especially vigilant and prepared for floods, because they will happen.
people should be careful about driving in floods because it is easy for
your engine to flood and strand you on a flooded highway. If you live in
a low area you should make sure your house is reasonably flood-proof,
and no matter where you live you should have flood insurance.
10.1.Organization of the Crisis Management;
Managing of crisis involves perfecting monitoring methods capable of
providing precise information on the situation to be managed, so that
managers can decide how best to intervene. In the case of a crisis, this implies
that information can be transferred in an optimum manner. However, it may
happen that the information transfer chain breaks down when the situation
becomes complicated, particularly when the magnitude of the event and the
way it occurs do not correspond to the formalization of the risk held by the
actors involved in its management. Given the diversity of actors concerned,
the multiplicity of decision levels (individual, communal, regional, national,
and even international), the fact that a state of readiness tends to become
toned down with time, and that land uses are subject to change, decisions
taken during a given risk situation may prove to be untimely and to lack
coherence. Our study therefore explored the different ways in which
prevention and emergency procedures were organized, firstly in a general and
theoretical manner, then on the basis of individual cases by identifying the
actors involved in these procedures and the ways in which the procedures
were reorganized following a crisis.
10.2.Creation of the Specific structures.
Floods, forest fires, bombings, swine flu: In less than a decade, Europe has
witnessed a series of large-scale natural disasters, widespread illness and two
major terrorist attacks. Catastrophes do not recognize national borders, and
policy makers have increasingly realized that cooperation within the Union is
a necessary prerequisite for efficient crisis management. Consequently, the
EU Member States are seeking more multilateral cooperation. A system of
common arrangements for handling emergencies or disasters has emerged,
which, due to its quick and ad-hoc development, may seem almost
impenetrable to newcomers to the field.
Crisis Management in the European Union: Cooperation in the Face of
Emergencies seeks to provide a much-needed overview of disaster and crisis
management systems in the EU. It provides a basic understanding of how EU
policy has evolved, the EU's mandate, and above all, a concise and hands-on
description of the most central crisis management arrangements.
10.3.Organization and implementation of operations.
Since ancient times floods have been seen as the most terrible calamity. In
many world religions they have been described as "God's punishment".
Among all natural calamities, flooding heads the list in sheer number of
catastrophes, its wide coverage of territory and the most economically
destructive.
Floods are caused by spills of rivers in high water, heavy rains, ice blocks on
rivers, heavy melting of ice, failure of dams due to earthquakes, bombing or
technological catastrophes at hydro facilities and diversions of rivers.
Floods cause rapid inundations of vast territories, where people are injured
and lost, agricultural and wild animals are killed, dwelling, industrial
buildings and other structures, utility plants, roads, electrical and
communication lines are damaged or destroyed.
Agricultural produce is destroyed, the structure of the soil and the relief of the
land is changed, productivity is interrupted and storage of raw material fuel,
food, forage, fertilizers and construction materials is either destroyed or
becomes unusable.
If a basement or underground floors are inundated, the water may cause
malfunction of equipment, which in turn, will cause electric accidents and
short circuits in electric systems.
In a number of cases floods may result in landslides and mudflows.
The basic characteristic features of floods are water expenditure, its volume
and the level to which it rises, the area covered, its duration, the speed and
composition of water flow.
10.4.1.More information’s.
During such accidents, people can be affected by the kinetic energy produced
by the burst waves. Mechanical injuries of varying severity could be the
result of:
 direct dynamic impact on human body by a burst wave
 traumatic effects caused by fragments of building and other structures
destroyed by the burst waves
 different items, involved in the motion by the burst waves
Magnitude and structure of population losses vary depending on a density of
population in a flooded area, time of a day, velocity of movement and height
of a burst wave, temperature of water and others.
At accidents in hydro dynamically hazardous objects, the total losses of
population in a burst wave area, can reach 90% at nighttime and 60% in
daytime. The irretrievable losses could be 75% at nighttime and 40% in
daytime, while the sanitary loses 25% and 60%, respectively.
Frequently, secondary flood effects could cause greater disaster than a flood
itself.
Prevention and minimization of adverse flood consequences includes
adequate organisational and engineering-technical measures such as:
reinforcement of the hydro-technical facilities, construction of additional
dams and banks to hold up water flows, accumulation of emergency material
(soil) to fill up holes, increase of height of existing dikes and dams, training
in emergency swimming, etc. A permanent hydrological forecast is necessary
including the estimates on potential and possible water levels in water
storages. Transport means has to be allocated and on disposal for organisation
of possible evacuation of population and of some significant values (valuable
paints, movable historic heritage, archives, etc.). Training of population and
special units to operate efficiently under flood condition should be organised.
Emergency alerts appear as “real tests of the monitoring and crisis
management measures already in place and, at the same time, bring into play
methods of interaction between the local and the global, the individual and
the communal, the profane and the expert, the subjective and the objective”
(translation) (Chateauraynaud, Torny, 1999: 15). As these two authors
demonstrate, a crisis alert is based on monitoring, surveillance and attention
and involves activation of a memory, whether the alert is in response to a
phenomenon that is unfolding or to a possibility, or whether it is a response to
an imminent catastrophe or the evaluation of a poorly-understood or
underestimated risk. Thus, the alert is not only a question of techniques,
sensors or alarms, but also the result of a process that creates a network of
actors and cooperation among institutional and non-institutional authorities.
“The alert takes the form of an approach, personal or collective, aimed at
mobilising authorities considered to be capable of acting and, at the very
least, of informing the public of a danger, the imminence of a catastrophe, or
the uncertain character of a company or technological choice”. From this
viewpoint, the alert is to be considered as "a capture of information".
Furthermore, the alert helps redefine the territory in both an anthropological
and administrative sense. This theoretical proposal is in line with a
perspective of the sociology of science and techniques and pragmatic
sociology which focuses analysis on the processes in progress, and the
configurations and reconfigurations of the action underway
11.0.What to do in case of the flood?
(good reactions, personal protective measures, school drills)
During a Flood
If a flood is likely in your area, you should:
 Listen to the radio or television for information.
 Be aware that flash flooding can occur. If there is any possibility of a
flash flood, move immediately to higher ground. Do not wait for
instructions to move.
 Be aware of streams, drainage channels, canyons, and other areas known
to flood suddenly. Flash floods can occur in these areas with or without
such typical warnings as rain clouds or heavy rain.
If you must prepare to evacuate, you should do the following:
 Secure your home. If you have time, bring in outdoor furniture. Move
essential items to an upper floor.
 Turn off utilities at the main switches or valves if instructed to do so.
Disconnect electrical appliances. Do not touch electrical equipment if
you are wet or standing in water.
11.1.More information’s
If you have to leave your home, remember these evacuation tips:
 Do not walk through moving water. Six inches of moving water can
make you fall. If you have to walk in water, walk where the water is not
moving. Use a stick to check the firmness of the ground in front of you.
 Do not drive into flooded areas. If floodwaters rise around your car,
abandon the car and move to higher ground if you can do so safely. You
and the vehicle can be quickly swept away.
Driving Flood Facts
The following are important points to remember when driving in flood
conditions:
 Six inches of water will reach the bottom of most passenger cars causing
loss of control and possible stalling.
 A foot of water will float many vehicles.
 Two feet of rushing water can carry away most vehicles including sport
utility vehicles and pick-ups.
12.0. What type of maps on flood exist?
Types of Maps
Maps differ in the amount and kind of information they give, and the graphic
devices used to convey the information. Some of the types of maps in
common use are the following:
Most flood maps today are not maps of real-life floods; they are maps of an
imaginary flood used to help communities get an idea of where especially
flood prone areas probably are. Sometimes these are called "100-year flood
maps," although that phrase is a little misleading because it is based on
statistical probabilities for some specific location, not for a region. There's a
good chance that a "100-year flood" will occur somewhere in your state every
year.
Flood forecasts (like the ones seen on TV newscasts) are made by the
National Weather Service for storms days in advance of the actual flooding.
These forecasts estimate the highest level the river will get, based mainly on
how much rain is expected. Unfortunately, the forecasts are made only for a
few specific places; they don't predict flood levels for anywhere except those
specific predictions are good only as a rough measure of how large the flood
is predicted to be. They don't tell you whether your house, or a school, or
your local sewage treatment plant is in danger of being flooded. Even if you
do live near a forecast point, the forecast is still only an elevation describing
the highest expected river level. It doesn't mean a lot to you unless you know
your elevation compared to the reference elevation, or "datum," of the
forecast point. What you want if you live in a floodplain, whether you live
near a forecast point or not, is a map that shows where flooding is expected.
12.1.More information’s
General Reference Maps: are maps, usually of relatively large areas, that
show major land and water areas, and such features as cities and political
boundaries. Atlas maps are generally of this kind.
Topographic Maps: prepared from original surveys and aerial photographs,
show all important natural and man-made features in relatively small areas,
usually in considerable detail. Military and most maps published by the U.S.
Geological Survey are of this kind.
Planimetric Maps: unlike topographic maps, make no attempt to show
varying elevations. They are drawn as though the earth were a plane (flat)
surface.
Charts: are maps used in sea and air navigation. They are specially designed
for plotting a course.
Thematic, Or Topical, Maps: provide information on a single subject. Usually
the mere outline of the area under consideration is shown. Against this
simplified background the special information is made to stand out by various
methods. For example, colors or patterns may be used to show the
distribution of rainfall, soil types, or election results. Dots may represent
places where a firm has retail sale outlets, the location of historical sites, or
the like. Variations of quantity—of rainfall, population, or crop yields, for
example—may be shown as variations in color or tones of gray; or isopleths
(“equal value” lines), such as the isobars on weather maps.
Cartograms: are map like diagrams. They present statistics in a pictorial way.
A cartogram might show, for example, the countries of the world in their
proper map position, but with each country distorted to a size proportionate to
its population.
What Are Maps?
Maps are two-dimensional (flat) representations of three-dimensional spaces.
People have been making maps for over 4,000 years, and they've come a long
way. We used to rely on explorers to visit faraway places before a map could
be made. We still have explorers that travel the Earth (and beyond) to
discover and map new places, but now we can also make and update maps
with information sent from satellites in space.
All maps have five basic elements to help you understand them (numbers
match image below):a title, to tell you the "who," "where," and "when" about
the map; orientation (north, south, east, or west);scale to determine distance;
a legend that explains the shapes, colors, and symbols used; a grid or
coordinates that help show where the map fits into a larger global area
Mapmaking
The science and art of mapmaking is called cartography. From cave paintings
and ancient European maps to new maps of the 21st century, people have
created and used maps to help define, explain, and navigate their way across
the planet and beyond.
12.2.What are they used for?
A number of new technologies and methods make the creation of flood
forecast maps possible. First is the ability to get very accurate elevations
throughout the floodplain quickly and affordably. This is done with "LIDAR"
technology (see more below). Second is a computer program (TRIMR2D)
that can simulate flood flows all across the floodplain and many, many miles
downstream from the forecast point. Third is spatial analysis software (GIS)
that turns the model results into maps and overlays them on other maps, like a
map of a neighborhood, or even onto an aerial photograph. Last is software
(IMS) that makes the maps available on the Internet in a flexible and userfriendly way.
LIDAR-Based System Collects Data Quickly, Accurately
Light Detection And Ranging (LIDAR) technology collects high-accuracy
elevation data (better than 1-foot accuracy) for very large areas very quickly
and at lower cost than traditional methods. The concept is quite simple: it's
essentially a laser rangefinder in an airplane, but it's no ordinary laser
rangefinder.
LIDAR systems use lasers that pulse tens of thousands of times a second. To
turn a laser-determined distance into the elevation of a point on the ground
requires sophisticated hardware and software. First, you need to know the
location of the airplane to within less than an inch at all times. This is done
with a high-precision Global Positioning System (GPS). Next, you must
know the orientation of the airplane (nose up or down, wings level or not)
with similar precision. This is done with Inertial Navigation Units (INUs) so
advanced and accurate they are considered military secrets and must be
licensed by the government.
The LIDAR system collects billions of elevation values, but commonly most
of the laser reflections are off of tree tops, shrubs, bridge decks, vehicles,
even telephone poles. Sorting through all these points to find the ones that are
really "on the ground" requires complex and often tedious computer
processing. But as difficult as all this sounds, it's still less expensive, faster,
and more accurate than anything that was available before.
What does LIDAR mean for flood mapping? It means that the computer
programs (flow models) can simulate floods over the entire floodplain, rather
than for just a few dozen cross-sections. In the past, elevation data was
collected manually in the field, and because that's very expensive, only crosssections were measured. Flow models therefore could simulate flow in one
dimension through these cross-sections. With elevation data available for the
entire floodplain, flow can be simulated everywhere. This type of simulation,
two-dimensional, gives us a much more detailed picture of where water will
go during a flood.
12.3.Can I get these maps and from where?
Flow models are computer programs that attempt to solve equations that
describe the physics of fluid flow. Because the set of equations is very large,
a critical feature of all models is the method they use to arrive at a solution.
The larger the area being modeled, the larger the set of equations, and the
more difficult it is to arrive at a solution. So the size of area that can be
simulated is limited by the solution method. Two-dimensional models, which
simulate flow throughout the entire floodplain, are much larger than onedimensional models, so the solution method is especially important.
The ability of a model to successfully solve large problems is referred to as
"stability." This is because of the iterative way the model attempts to solve
the problem, closing in gradually on the solution. For very difficult problems,
the model will perpetually overshoot the answer and never reach a solution—
a condition called "numerical instability." TRIMR2D is a two-dimensional
model that uses a unique and especially stable solution method, so it can
solve much larger problems—for much larger areas—than other twodimensional models. Stability limits not only the size of the area that can be
simulated, but also the ability to solve flow predictions that involve very
large or fast changes in flow. TRIMR2D has demonstrated that it can solve
equations not only for large areas, but also for problems that have large and
fast flow changes.
12.4. More information’s
The stability of TRIMR2D is due to a solution method that separates the
more stable terms in the equations from the less stable terms, and then solves
them in a manner that minimizes the effect of the less stable terms. In
modeling terms, TRIMR2D is called a semi-explicit, semi-lagrangian, finitedifference, two-dimensional, depth-averaged hydraulic model.
GIS Draws the Map
A Geographic Information System, GIS, is a state-of-the-art database that
includes a location with each piece of information. A GIS is used to
manipulate, calculate, and process information that is inherently spatial in
nature—all of the data is related to some point on the ground. Elevation data
is a good example; all points on the ground have their own value of elevation.
A GIS also can make maps of these data; they are so good at making maps
that some people mistake them as merely mapping tools.
For making flood forecast maps, the GIS uses one of several common
processing methods—cell-based, or raster, calculation. This method is well
suited for processing the solution provided by TRIMR2D, which is in a raster
format (raster means all data is for locations that are evenly spaced on the
ground, like a checkerboard).
The GIS uses the model results to make maps of the entire floodplain
showing areas that are likely to be flooded and how deep the water may get,
when the floodwater will likely first arrive, and when the flood will crest.
Internet Map Server Delivers the Information
To deliver these information layers in a useful manner to emergency
responders and the public, an Internet Map Server (IMS) is employed. This
system allows the IMS author to make a variety of data layers available to the
end user so that they can customize the map to their needs by selecting or
turning off various information or reference layers. The information available
and the appearance of symbols are scale dependent, allowing a great amount
of flexibility to both the author and the user.
Where maps were once hand-drawn on paper, most modern cartographers
now use a variety of computer graphics programs to generate new maps. For
example, we have technologies like Global Positioning System (GPS) for
navigation and Geographic Information Systems (GIS) to analyze and display
information.
Global Positioning System (GPS)
GPS is a global positioning system that uses satellites to pinpoint your
location anywhere on the planet.
How does it do that? Your GPS-enabled device—such as a cell phone, car
navigation system, or handheld GPS unit—determines your location by
measuring the time delay between when a satellite sends a signal and when
your unit receives it. With more than 24 GPS satellites in orbit around the
Earth, GPS has become very popular for navigation on land, sea, and air, as
well as an important tool for mapmaking and land surveying.For each
question a maximum of 20 lines on the main page and a link to a specific
page with additional information related to that specific question.Geographic
Information Systems (GIS)
GIS is a computer-based technology that enables people to quickly combine
different types of information (such as population, precipitation, and
transportation) on a single map. GIS represents real-world objects (roads, a
house, rainfall amount, land elevation) with digital information, and GIS
technology can be used for all kinds of things—scientific investigations,
managing natural resources, cartography, and route planning, to mention just
a few.
Sea level maps