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close this bookIntroduction to Hazards - 1st Edition (Department of Humanitarian Affairs/United Nations Disaster Relief Office - Disaster Management Training Programme - United Nations Development Programme , 1992, 168 p.)
close this folderCLIMATIC HAZARDS
View the documentPart 2.1: Tropical cyclones
View the documentPart 2.2: Floods
View the documentPart 2.3: Drought

Part 2.2: Floods


This chapter of the module aims to improve your understanding of:


the causes of floods and factors which intensify their effects

impacts of floods on human settlements

flood control, prevention and preparedness measures

flood forecasting and warning systems

Introduction


Throughout history people have been attracted to the fertile lands of the floodplains where their lives have been made easier by virtue of close proximity to sources of food and water. Ironically, the same river or stream that provides sustenance to the surrounding population, also renders these populations vulnerable to disaster by periodic flooding. Floods can arise from abnormally heavy precipitation, dam failures, rapid snow melts, river blockages or even burst water mains. Flood disasters are second only to droughts in the total number of people affected world wide.

FLOOD HAZARD DATA SHEET

Number killed by declared flood disasters, 1980-89:16.108
Number affected: 279,330,901 (OFDA, 1990)

Selected severe flood disasters

Year

Location

Deaths

Losses In US$ million

1966

Italy

113

1,300

1983

Peru, Ecuador

500

700

1983

Spain

42

1,250

1986

China

260

1,210

1987

USSR

110

550

1987

Switzerland

0

700

1987

Bangladesh

1,600

1,300

1988

Thailand

371

300

1988

Bangladesh

3.000

1,200

1990

Tunisia

25

211

1991

China

2,295

12,500

Source: Nature and Resources, Vol. 27. No.1, 1991

Causal phenomena

Types of floods

Flash floods - These are usually defined as floods which occur within six hours of the beginning of heavy rainfall, and are usually associated with towering cumulus clouds, severe thunderstorms, tropical cyclones or during the passage of cold weather fronts. This type of flooding requires rapid localized warnings and immediate response by affected communities if damage is to be mitigated. Flash floods are normally a result of runoff from a torrential downpour, particularly if the catchment slope is unable to absorb and hold a significant part of the water. Other causes of flash floods include dam failure or sudden breakup of ice jams or other river obstructions. Flash floods are potential threats particularly where the terrain is steep, surface runoff is high, water flows through narrow canyons and where severe rainstorms are likely.


Truck carried away by flooding

Mass Media Production Centre, Manila, UNDRO News, Sep/Oct 1984


Figure 2.2.1 - Flooding and its causes

Natural Hazards, Disaster Management Center 1989.

River floods - River floods are usually caused by precipitation over large catchment areas or by melting of the winter's accumulation of snow or sometimes by both. The floods take place in river systems with tributaries that may drain large geographic areas and encompass many independent river basins. In contrast to flash floods, river floods normally build up slowly, are often seasonal and may continue for days or weeks. Factors governing the amount of flooding include ground conditions (the amount of moisture in the soil, vegetation cover, depth of snow, cover by impervious urban surfaces such as concrete) and size of the catchment basin. In some larger semi-arid countries, such as Australia, inland flooding of dry or stagnant rivers may occur many weeks after the onset of heavy coastal monsoon or cyclonic rain has directed river flows many hundreds of km inland, and in the complete absence of any sign of disturbed weather.

Historical records of flooding of towns on the main river flood plains prove unreliable for flood protection purposes due to the varying source of the contributing river tributaries.

Coastal floods - Some flooding is associated with tropical cyclones (also called hurricanes and typhoons). Catastrophic flooding from rainwater is often aggravated by wind-induced storm surges along the coast. Salt water may flood the land by one or a combination of effects from high tides, storm surges or tsunamis. (See the chapters on tsunamis and tropical cyclones for more information.) As in river floods, intense rain falling over a large geographic area will produce extreme flooding in coastal river basins.

Q. Is your community or country susceptible to flooding? What types?

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How do humans contribute to flooding?

Floods are naturally occurring hazards. They become disasters when human settlements occupy the floodplain.

Floods are naturally occurring hazards. They become disasters when human settlements occupy the floodplain. Population pressure is now so great that the risks associated with floods have been accommodated because of the greater need for a place to live. In the United States, for example, billions of dollars have been spent on flood protection programs since 1936. In spite of this the annual flood hazard has become greater because people have moved to and constructed upon flood plains faster than the engineers can design better flood protection.

Increase in population combined with poor resource management have resulted in new types of flooding. Conversion of forests in the catchment area to pasture and arable land means that less water is held in the upper reaches of the catchment basin, and the increased runoff water flows rapidly to the plains, with the effect of more frequent, unexpected and severe flooding.

Another type of flood becoming more common is urban flash flooding. Buildings and roads cover the land preventing infiltration so that rainwater runs over the impervious surfaces forming artificial streams. Inattention to maintenance of drainage systems, especially after long dry spells when dust, debris and overgrown vegetation have blocked natural water flow, can accentuate the degree of flash flooding.

General characteristics

Floods may be measured and analyzed by the following criteria:

Depth of water - Building foundations and vegetation will have different degrees of tolerance to being inundated with water.

Duration - Damage or degree of damage to structures, infrastructure and vegetation is often related to the length of time of inundation by water.

Velocity - Dangerously high velocities of flow may create erosive forces and hydrodynamic pressure which may destroy or weaken foundation supports. These may occur on the floodplains or in the main river channel.

Rate of rise - Estimation of the rate of rise and discharge of a river is important as a basis for flood warnings, evacuation plans, and zoning regulations.

Frequency of occurrence - The cumulative effects and frequency of occurrence measured over a long period of time will determine what types of construction or agricultural activities should take place on the floodplain.

Seasonality - Flooding during a growing season may completely destroy crops while cold weather floods from snow melts may seriously affect the functioning of a community.


Predictability

Flooding, resulting from precipitation or snow melt in the catchment system, or from upstream flooding, is predictable from about 12 hours to as much as several weeks ahead.

Riverine flood forecasting estimates river level stage, discharge, time of occurrence, and duration of flooding, especially of peak discharge at specific points along river systems. Flooding, resulting from precipitation or snow melt in the catchment system, or from upstream flooding, is predictable from about 12 hours to as much as several weeks ahead. Forecasts issued to the public result from regular monitoring of the river heights and rainfall observations. Hash flood warnings, however, are dependent solely on meteorological forecasts and a knowledge of local geographical conditions. The very short lead time for the development of flash floods does not permit useful monitoring of actual river levels for warning purposes.

For comparison with previous flood events, and conversion to warning information, assessment of the following elements should be included: flood frequency analysis, topographic mapping and height contouring around river systems with estimates of water holding capacity of the catchment area, precipitation and snow melt records, soil filtration capacity, and (if in a coastal area) tidal records, storm frequency, topography, coastal geography and breakwater characteristics.

An effective means of monitoring floodplains is through remote sensing techniques such as Landsat. The images produced by the satellites can be interpreted and used to map flooded and flood-prone areas. Other efforts to improve forecasting are being implemented by UN organizations such as the World Meteorological Organization using World Weather Watch and Global Data Processing Systems. These systems are strategic when flood conditions exist across international boundaries. The great majority of river and flash floods forecasts, however, depend on observations made by national weather services for activation of flood alert warnings.

Vulnerability

At notable risk in flood plain settlements are buildings made of earth or with soluble mortar, buildings with shallow foundations or non-resistant to water force and inundation. Infrastructural elements at particular risk include utilities such as sewer systems, power and water supplies, machinery and electronics belonging to industry and communications. Of great concern are food stocks and standing crops, confined livestock, irreplaceable cultural artifacts, and fishing boats and other maritime industries.

Other factors affecting vulnerability are lack of adequate refuge sites above flood levels and accessible routes for reaching those sites. Similarly, lack of public information about escape routes and other appropriate response activities renders communities more vulnerable.

Typical adverse effects

Physical damage

Structures are damaged by a) force of impact of flood waters on structures b) floating away on rising waters c) becoming inundated d) collapsing due to undercutting by scouring or erosion and e) damage by water-borne debris.

Damage is likely to be much greater in valleys than in open, low-lying areas. Flash floods often sweep away everything in their paths. In coastal areas, storm surges are destructive both on their inward travel and again on the outward return to the sea. Mud, oil and other pollutants carried by the water are deposited and ruin crops and building contents. Saturation of soils may cause landslides or ground failure.

Casualties and public health

Major floods may result in large numbers of deaths from drowning, particularly among the young and weak but generally inflict few serious but non-fatal injuries requiring hospital treatment.

Currents of moving or turbulent water can knock down and drown people and animals in relatively shallow depths. Major floods may result in large numbers of deaths from drowning, particularly among the young and weak but generally inflict few serious but non-fatal injuries requiring hospital treatment. Slow flooding causes relatively few direct deaths or injuries, but often increases occurrences of snake bites.

Endemic disease will continue in flooded areas, but there is little evidence of floods directly causing any large scale additional health problems apart from diarrhea, malaria and other viral outbreaks eight to ten weeks following the flood.


Water supplies

Open wells and other groundwater supplies may be contaminated temporarily by debris carried by flood waters or salt water brought in by storm surges. They will, however, only be contaminated by pathogenic organisms if bodies of people or animals are caught in the sources or if sewage is swept in. Normal sources of water may not be available for several days.


Application of remote sensing data to flood prone areas:

Honduras coastal plain - In September 1974, the coast of Honduras was flooded by Hurricane Fifi. The government of Honduras requested assistance from OAS/DRDE for mapping of the floodplain for use in an integrated development study to rebuild the coastal areas. Using Landsat data sheets, pre-flood and post-flood imagery was overlapped to show the areas susceptible to flooding and where prevention and mitigation measures and land use zoning would be necessary.

Pilcomayo River Floodplain: Recurrent flooding along the Pilcomayo River in southwestern Paraguay, prompted the Paraguayan Government to draw up a hazard map of the floodplain. Several different maps such as those showing desertification and soils were combined with Landsat maps to draft floodplain boundaries and hazard zones, using overlay mapping. The maps showed the changes in the river channel over time and served to demonstrate the highly dynamic nature of the floodplain, indicating continuous need for floodplain monitoring. Further analysis was used to assess flood hazard vulnerability.

Crops and food supplies

An entire harvest may be lost together with animal fodder resulting in long-term food shortages. Food stocks may be lost by submersion of crop storage facilities resulting in immediate food shortages. Grains will quickly spoil if saturated with water even for a short time.

Most agricultural losses result from the inundation of crops. Susceptibility to inundation depends on the type of crop and duration of flooding. Some crops, such as taro are quickly killed by relatively small amounts of flood water. Others may be able to resist submersion but may die eventually if large amounts of standing water stagnate as in the 1988 Bangladesh flood.

Large numbers of animals, including draught animals, may be lost if they are not moved to safety. This may reduce the availability of milk and other animal products and services, such as preparation of the land for planting. These losses, in addition to possible loss of farm implements and seed stocks, may hinder future planting efforts.

Floods bring mixed results in terms of their effects on the soil. In some cases, land may be rendered infertile for several years following a flood due to erosion of the topsoil or by salt permeation in the case of coastal floods. Heavy silting may either have adverse effects or may significantly increase the fertility of the soil.

In coastal areas where fish provide a source of protein, boats and fishing equipment may be lost or damaged.

On the positive side, floods may flush out pollutants in the waterways.

Other positive effects include preserving of wetlands, recharging groundwater, and maintaining the river ecosystems by providing breeding, nesting, and feeding areas for fish, birds and wildlife.

Possible risk reduction measures

The majority of deaths and much of the destruction created by floods can be prevented by mitigation and preparedness measures.

The majority of deaths and much of the destruction created by floods can be prevented by mitigation and preparedness measures. The first step involves identifying vulnerable elements by preparation of a flood hazard map and then integrating that information into a plan for preparedness and development. A strategy might combine regulation of land in the floodplains with flood control measures. Planners may seek contribution from a variety of disciplines to assess risk, the level of acceptable risk, and viability of proposed activities. Information and assistance may be obtained from different sources ranging from international agencies to the community level.

Mapping of the floodplain - Floods are normally described in terms of statistical frequency using the 100 year flood plain event parameters for flood mitigation programs. The 100 year flood plain describes an area subject to a 1% probability of a certain size flood in a given year. Depending on the degree of acceptable risk that is selected for an evaluation, other frequencies may be chosen such as 5,20,50, or 500 year floodplains.

The basic map is combined with other maps and data to form a complete picture of the floodplain. Other inputs include frequency analysis, inundation maps, flood frequency and damage reports, slope maps and other related maps such as land use, vegetation, population density and infrastructural maps. In some developing countries, obtaining extensive long term information may be difficult. Remote sensing techniques provide an alternative to traditional techniques of floodplain mapping and can be equally or more cost effective as they allow estimates of data otherwise requiring labor intensive collection methods, as in hydrology studies over extensive areas.

Multiple hazard mapping - Floods often cause, occur in conjunction with, or result from other hazards. A multiple hazard map, known as a composite, synthesized or overlay map, serves to highlight areas vulnerable to more than one hazard. It is an excellent tool for designing a multiple hazard mitigation and emergency plan. It may, however, not be adequate for site-specific, hazard specific engineered activities.

Land use regulations ensure that flood risks are not made worse by ill-conceived new land uses.

Land use control - The purpose of land use regulations is to reduce danger to life, property and development when high waters inundate the floodplains or the coastal areas. Land use regulations ensure that flood risks are not made worse by ill-conceived new land uses. Of particular concern are regions of urban expansion. The following elements should be addressed.

1. Reduction of densities: In flood prone areas, the number of casualties is directly related to the population densities of the neighborhood at risk. If an area is still in the planning stages, regulation of densities may be built into the plan. For areas already settled, especially squatter settlements, regulation of density can be a sensitive issue and would have to address the socioeconomic implications of resettlement. Unfortunately, many situations exist where dense unplanned settlements are located on floodplains. Planners must incorporate measures to improve sites and reduce vulnerability.

2. Prohibiting specific functions: No major development should be permitted in areas found to be subject to flooding once every 10 years on average. Areas of high risk can be used for functions with a lower risk potential such as, nature reserves, sports facilities and parks. Functions with high damage potential such as a hospital are permitted in safe areas only.

3. Relocation of elements that block the floodway: In addition to the obvious danger of being washed away, buildings blocking the floodway may cause damage by trapping floodwaters which then overflow into formerly flood free zones.

4. Regulation of building materials: In certain zones wooden buildings and other light structures should be avoided. In some cases, mud houses are permitted only if flood protection measures have been taken.

5. Provision of escape route: Neighborhoods should have clear escape routes and provision of refuge areas on higher ground.


Figure 2.2.2 - Schematic flood plain regulation map


Figure 2.2.3 - Schematic flood plain regulation map

Natural Hazards, Disaster Management Center, 1989.

Other preventative strategies include:


the acquisition of floodplain land by developmental agencies, perhaps by swaps that provide alternatives for building sites


establishment of incentives (loans or subsidies, tax breaks) to encourage future development on safer sites using safer methods of construction


diversification of agricultural production such as planting flood resistant crops or adjusting the planting season; establishing cash and food reserves


reforestation, range management and animal grazing controls to increase absorption (see chapters on deforestation, desertification)


construction of raised areas or buildings for use as refuge if evacuation is not possible.

Flood control

For developing countries with intensively utilized floodplains, considerable political influence in conjunction with the cooperation of the communities may have to be employed.

As mentioned above, land use controls will be of limited use in already developed floodplains. Yet, changes must be implemented to reduce a community's vulnerability to flood damage. For developing countries with intensively utilized floodplains, considerable political influence in conjunction with the cooperation of the communities may have to be employed. The most commonly used options are:

Existing channel improvements - Deepening and widening the river bed are methods to increase capacity and thus reduce the area of the floodplain.

Diversion and relief channel construction - New channel construction may be a feasible alternative relative to the cost of moving a settlement. Several options exist for channel construction such as open grass-lined channels, concrete or rock lined channels. Great care must be exercised in the design and construction of diversion channels because of the possible environmental impacts and necessary safety features. Costs may be prohibitive for such highly engineered works.

Dikes and dams - These facilities are capable of storing flood water and releasing them at manageable rates. Again, careful engineering is required to anticipate maximum flood levels. If exceeded, the damage caused may be much higher than if the facility had not been built. Dams and other retention facilities may give the public a false sense of security if not properly engineered and constructed.

Flood-proofing - Individual property owners may reduce the risk of damage by strengthening buildings to a) resist the water's force and b) retain integrity when inundated with water. Newly constructed buildings should have foundations which are not susceptible to scouring

Protection against erosion - An important element of flood defense is protection against erosion. Streambeds should be stabilized with stone masonry or vegetation especially near bridges.

Site improvement - The elevation of sites can be an effective option for individual or group dwellings.

Q. What are some possible risk reduction measures which may be used in regard to flood hazards?

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ANSWER

Some of the possible risk reduction measures which can be used in relation to flood hazards are: preparation of floodplain mapping, multiple hazard mapping and associated land use controls, physical flood control structures (existing river channel improvement, diversion channels, and dikes and dams), individual site improvements, and individual structural modifications.

Specific preparedness measures

Flood forecasting and warning systems

Case studies in some countries have shown that flood forecasts and warnings can reduce damage between 6 and 40 percent (WMO). Flood detection systems which provide the basis for flood forecasts, warning and preparedness systems range from inexpensive networks involving volunteers who observe rainfall and stream stages to sophisticated networks of gauges and computerized models. A system known as ALERT (Automated Local Evaluation in Real Time) has demonstrated a cost effective capability to protect life and property through participation by local level agencies. Field stations designed as complete modules are maintained locally.

Whatever the method for warning the public, communication systems must be must be well planned. Evacuation procedures should be practiced on a regular basis. Ways to disseminate warnings include radio, television, warning sirens or bells, public address systems, and at village level by bicycle and on foot. National warning systems are more vulnerable to failure because of problems disseminating warnings locally in a clear manner which reach the target community in time for action to take place. National warning systems are more effective in warning urban populations. Rural systems require respected local leaders to issue clear instructions and prior arrangements for protecting assets and reaching evacuation sites.


Figure 2.2.4 - Schematic of flood warning system

Community participation

Inhabitants of flood prone areas usually have a number of traditional methods at their disposal for coping with floods. In countries such as Bangladesh where a great number of people and area of land is vulnerable to flooding, governments would be hard pressed to provide complete coverage with even simply engineered mitigation measures. Some aspects of flood planning and response can be managed at the village level and upgraded with outside assistance. These are:


issuing warnings at the local level


participating in flood fighting by organizing work parties to repair embankments or clear debris from drainage areas, pile sandbags and stockpile needed materials


facilitating agricultural recovery


planning emergency supplies of food and clean drinking water


identifying traditional mitigation and preparedness measures and determining their effectiveness.

Programs to promote public awareness of the flood hazard may contain the following components:


Explanations of the function of floodplains, location of local floodplains and drainage patterns.


Identification of flood hazards and warning signs


Encouraging individuals to floodproof their possessions and develop personal escape plans


Awareness of community evacuation plans and warning systems, and appropriate post-disaster activities


Encourage personal responsibility for flood prevention/mitigation in day to day living practices. This would include use of proper farming practices, prevention of deforestation and maintenance of drainageways.


Andrew Maskrey, Disaster Mitigation, A Community Based Approach.

Master plan

The basic guide that provides local officials and developers or landowners with information about the floodplain is called the master plan. The master plan should contain land use control regulations and a public information program. Steps to be taken in developing a master plan are as follows:

1) Obtain an accurate mapping of the area.

2) Develop the hydrology for several frequencies of flood occurrence including the 100 year.

3) Delineate the floodplains for the flood frequencies using existing channel and floodplain conditions.

4) Estimate flood damages for various frequencies and develop flood damage frequency curves and average annual damages.

5) Conduct a review of all possible flood damage reduction alternatives such as dams, channels etc.

6) Prepare preliminary designs and cost estimates for the remaining alternatives and delineate residual floodplains for the frequencies being used.

7) Determine residual flood damages for each alternative.

8) Complete a cost benefit analysis for each alternative.

9) Review each alternative for other factors such as political considerations, multiple use opportunities and environmental factors.

10) Select an alternative or combination acceptable to each affected jurisdiction.

11) Publish a master plan report with documentation of the above process.


The ABC$D of Your Next Flood - A public information publication of the Australian Bureau of Meteorology.

Typical post disaster needs

The initial response to flooding by local authorities should include:


search and rescue

medical assistance disaster assessment

short term food and water provision

water purification

epidemiological surveillance

temporary shelter

The secondary response should include:


repair or reconstruction


reestablish or create employment


assist with recovery of agriculture through loans, distribution of farm equipment and tools and animals


assist with recovery of small businesses and fisheries


CASE STUDY

The Relief operation following the 1986 floods of Lake Titicaca in Puno District, Peru

Natural disasters are frequent in Peru due to its rugged topography. The area surrounding Lake Titicaca has been subjected throughout recorded history to regular periods of drought and flooding. The region of Puno is situated in the southeast and shares a border with Bolivia. It is part of the Altiplano Andino where heavy rain falls in the summer months and intense drought occurs in the winter. Observations carried out by the government planning office indicated a trend toward heavy rains since 1983 in this area. Puno is one of the country's poorest regions. The population is very dense near the lake where Andean farmers depend on the rich soils for agriculture and livestock.

Precipitation beginning in November 1985 was much higher than average causing a gradual rise in Lake Titicaca's water level. In early 1986, the lake began to overflow its basin, resulting in extensive flooding along lake shores and three tributary rivers. Villages and crops were slowly inundated as waters encroached upon the countryside. In March of 1986, a locally compiled survey numbered the victims at 240,000 persons, or about 20% of the population. Included in the flooded land was more than 38% of the planted land and more than 80% of the total arable land. Although the urban areas were severely affected, the consequences of the floods more heavily impacted on the rural population, where earthen houses soon gave way to the advancing waters.

The Government of Peru, which had not realized the extent of damage until the March report, sought international assistance and received support from the United Nations and voluntary organizations. The government then developed an emergency relief plan to be administered by the National Civil Defense. Prior to this time, no local or government action had been taken to control the situation. The priorities of the plan included:

1. Provision of immediate care for rural and urban populations by evacuating inundated areas and resettling populations and animals in temporary settlements.

2. Provision of acceptable shelters, blankets or clothing, food and water and health surveillance.

3. Rehabilitation of damaged communication lines.

The occurrence of heavy precipitation seemed to have been viewed by both central government and local authorities as normal, despite dome evidence of heavy rain trends, until the extent of damage became critical. This may have resulted from response patterns of previous years when local residents organized themselves to deal with the flooding and no pressing need existed for government assistance.

As there was no preparedness plan, there was no immediate response. When the plan was elaborated it seemed logical and coherent but was difficult to implement for the following reasons:

1. The coordination between national authorities and local representatives was inadequate. The staff members were not prepared and were disorganized.

2. No preparations existed for reception of international aid, including clearance of goods. The roles of the relief organizations, including international and national organizations (both governmental and nongovernmental) in the management of relief assistance were not clearly defined.

3. The population had been evacuating itself prior to government intervention, looking with difficulty for safe refuge. This exodus produced conflicts.

The relief process was impaired by lack of preparedness. The rehabilitation process, however, may prove to be even more problematic. Valuable farming land has been lost to the lake and may not be recovered for some time.

Options include continuing the traditional lifestyle and accepting the occasional disaster, resettling part of the Puno population permanently, or developing flood control technologies and safe agricultural practices.

Q. What preparedness measures may have prevented the problems confronted in the emergency relief operations in Puno?

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ANSWER

The preparation of a flood emergency plan, including the roles of all involved organizations, and in anticipation of international intervention. The preparation of a flood evacuation plan including designated shelters. Community participation in flood planning and response. Establishment of a flood forecasting and warning system and network to communicate local conditions to central agencies. Studies of flood plain areas and preparation of a master plan to determine potential

Discuss the perspectives of these three groups on the Lake Titicaca flooding disaster: the Government of Peru; the people of Puno affected by flooding; the relief organizations.

Discuss the pros and cons of the three rehabilitation options.

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References

"Automated Local Evaluation in Real Time (ALERT): A Cooperative Flood Warning Service for Your Community", National Weather Service, Western Region, Box 11188 Federal Building, Salt Lake City, Utah 84147, USA.

Askew, Arthur, "Learning to Live With Floods", in Nature and Resources, Vol. 27, No. 1, 1991, p.4-8.

Cuny, Frederick C., "Living with Floods: Alternatives for Riverine Flood Mitigation", in Development: from vulnerability to resilience, p. 62-73.

Disaster Management Center, Natural Hazards: Causes and Effects, University of Wisconsin Board of Regents, 1986.

Facing Geologic and Hydrologic Hazards, W.W. Hays, editor, U.S. Government Printing Office, Washington, D.C., 11981.

Khan, H.R., "Floods and Flood Preparedness", Disaster Management Course, Asian Disaster Preparedness Center, Asian Institute of Technology, Bangkok, Thailand.

Natural Disaster Reduction: How Meteorological and Hydrological Services Can Help, WMO - No. 722, Geneva, 1989.

Sztorch, L., and V. Gicquel, J.C. Desenclos, "The Relief Operation in Puno District, Peru, after the 1986 Floods of Lake Titicaca," in Disasters, Vol. 13, No. 1,1989, p. 30-40.

UNDRO, Mitigating Natural Disasters, Phenomena, Effects and Options, United Nations, New York, 1991.

UNDRO NEWS, "Unprecedented Hoods Devastate Bangladesh", Sept/Oct. 1988.