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Living with floods: alternatives for riverine flood mitigation

Frederick C. Cuny

Most efforts designed to reduce the effects of floods have focused on such structural measures as the construction of dams or embankments (polders, levees, and the like). Many of these large-scale, capital-intensive projects have been questioned on both technical and environmental grounds. Many development experts question whether large-scale flood control projects are economically suitable for the least-developed countries, since they increase the country’s debt significantly for little economic return. And some flood control projects may be counterproductive. Embankments may foster unrealistic expectations that all flooding can be prevented and stimulate movement onto floodplains, thereby increasing total risk. In recent years, there has been increased interest in alternative strategies for protecting the floodplains, especially in rural areas. A key strategy has been to encourage people living in rural areas and in some small communities to adapt to floods and to capture their benefits for economic development. Traditional rural societies have developed many ways to adapt to floods and their consequences. These strategies can often be adopted or modified into a national “living with floods” strategy. Where this strategy has been applied, it has been cost-effective, easy to implement, and compatible with the environment. These measures can be applied before and after floods. More important, they can be incorporated in long-term development programs at little extra cost.

Flooding along the low-lying plains near rivers is the most widespread hazard in the world. Historically, people have avoided living in flood-prone areas but as populations grow and land becomes scarce, more and more people are forced to use these areas for activities that floods can harm. Many societies have developed a portfolio of counterflood actions designed to control flooding, prevent disaster, and, where possible, to harness the floods for such uses as irrigation, navigation, and aquaculture.

The technology to control floods exists, but in recent years concern has grown about the environmental consequences of flood control measures undertaken over large areas. Some experts have challenged the cost-benefit claims of flood control proponents, arguing that the benefits are slow to accrue and cannot always be accurately accounted for. Many have questioned whether sophisticated flood control works are appropriate for developing countries, given their high costs and the countries’ added debt burdens.

As nations threatened by widespread flooding plan their development strategies, they must understand that there are options - ways to live with floods and harness their benefits with limited flood control efforts. Many of these approaches are cost-effective and can be carried out by local communities with help from government and development agencies. They capitalize on people’s self-reliance and in the long term reduce costs and speed up protection. Countries that adopt them can adopt capital-intensive programs and to a large extent eliminate costly, never-ending maintenance operations.

The importance of indigenous responses cannot be overemphasized. In remote rural areas where government assistance may be delayed or virtually impossible to provide, these responses may determine how quickly and effectively a family recovers. It is important not only to understand them but to ensure that outside responses do not inhibit or discourage people from applying them.

Preventing floods is not a universal solution. In many cases flood control is not only feasible but more practical because urban areas, vital infrastructure, and critical communication and transportation networks must be protected. But encouraging communities to adapt to floods can be considered as an alternative or complement to capital-intensive structural flood control measures (such as embankments, dams, diversions, and river draining works). Knowing the difference between types of floods is essential for choosing the appropriate strategy.

Types of floods

There are four basic types of floods: flash floods, standing floods, sea surges, and riverine floods.

Flash floods occur as a result of the rapid accumulation of runoff waters from a rainstorm in a mountainous or hilly area. The water usually collects in relatively confined areas - such as gullies, wadis, or arroyos - then cascades until it reaches another stream or a wider, less restrictive area where the water spreads out and its velocity is reduced. The speed of the flood and the debris it carries are what make flash floods dangerous. (Flood velocity is determined by the steepness of the grade of the confined area.) Historically, people have avoided living in constricted areas, although some economic activities (such as sand or gravel extraction) have been carried out there. With rapid, unchecked urbanization, this has changed. Many poor people are forced to live in these areas - so the threat to human life is growing annually. For the most part, the best strategy in arroyos is still prevention. Downstream structural measures, such as diversions and check dams, provide some protection.

Standing floods occur when accumulated rainwater can neither drain off the surface rapidly nor be absorbed quickly into the soils or the water table. Standing floods usually cover relatively small areas. Many are caused by poorly designed transportation networks, such as roads and railways, that cut across natural drains and cause the water to back up behind roadbeds. Little can be done to prevent standing floods except engineering works to collect the water, in canals, and transport it to natural drainage zones or pump it into passing streams or onto lands on which it will do no damage. If the cause of the floods is a man-made restriction, bridges or culverts can often reduce the floods to an acceptable level.

Coastal flooding can occur as a result of storm surges (wind-blown masses of water caused by tropical cyclones - also known as hurricanes or typhoons - or storm-related high tides). Residents of coastal areas have adopted a variety of measures to reduce the impact of these floods. They have built communities on raised platforms, for example, or houses on stilts, and seawalls and other structures to absorb the force of storm surges. They have adopted such escape strategies as evacuation and community shelters as a response to both high winds and floods.

Riverine floods occur when a river overflows its normal streambed because of heavy rains anywhere in the river’s watershed. Normally, the area of flooding can be predicted, usually on the basis of topography and past flood history. The overflow area - the floodplain - may be a few hundred meters or dozens of kilometers wide. As a river gets closer to the sea, it usually passes through an area of alluvial buildup. This area, known as the river’s delta or fan, is normally fairly flat - and rivers tend to meander in wide lazy Ss as they slow down and empty into the ocean. In these deltas, flooding can be widespread; the extent of the flood and the height of the waters can be affected by rains far up the watershed and by ocean tides, which can slow the discharge of the river and raise water levels at high tide.

Of all floods, riverine floods are the most difficult to control and the ones for which a “living with floods” strategy is most feasible. To understand why, let us examine the ecology of riverine areas and the benefits of riverine flooding.

Riverine ecology

Riverine areas are important ecological zones. The world’s great rivers carry minerals and nutrients to the seas and form delicate, highly complex delta ecosystems that are crucial in maintaining the balance of nature. Most important, the marshlands and swamps provide a bridge between salt- and freshwater environments. Next, the tidal and saltflats provide a way to keep excessive salt penetration from moving inland. Then, on the coastal plains, landforms build up and human habitation becomes feasible and productive. As the rivers slow down, they deposit sediment which gradually creates sandbars in the streambeds. The sandbars divide and redirect the waters, eroding some areas and building others up. The sediment buildup offshore eventually extends the land mass outward into the ocean.

The alluvium the rivers deposit is the key to the deltas’ richness. This sediment is a mixture of all the topsoils the rivers pass through. The heavier, rocky materials settle out farther upstream. The suspended solids that reach the fan are fine and light and usually rich in nutrients and humus. In these rich soils, agriculture flourishes; the deltas of the world are also the world’s breadbaskets. Rich soil and plentiful water ensures that farmers can grow crops annually, if not semiannually. Even a small amount of land can produce enough crops for societies to prosper - and it is not unusual for these areas to be densely populated. Agriculture is not all that flourishes in this environment. In waters rich in nutrients, fish abound - in both the rivers and the discharge zone.

A riverine environment shapes the daily life of societies along its banks. Agriculture and aquaculture dominate the economy. The people’s basic diet depends on abundant sources of water and the flora and fauna within.

A riverine environment promises perennial floods. Usually, not a year will go by without some part of the delta flooding to some degree. To an outsider it might appear that floods are something to which riverbank societies must adapt to survive but most often the disaster would be if floods did not occur periodically. The benefits of floods far outweigh their negative effects. Many rural societies welcome flooding. In Bangladesh, the Barsha festivals celebrate the flood season and, when waters cover some areas, people take to their boats and venture out of their villages to trade and renew commercial and familial links.

The benefits of flooding

After a severe flood, it is often hard to remember that floods also have a positive side. What are some of the benefits?

· Floods deposit rich silts and replenish top-soil with nutrients vital to agriculture. After widespread flooding, there is almost always a bumper crop the next harvest season that partially makes up for the losses from flooding.

· Floodwaters carry nutrients that stimulate fish development and increase the number of fish. Floods may restock fish in isolated ponds, lakes, or streams that do not flow year round.

· Some ecologists suggest that floods improve the natural varieties of food grains, destroying the weaker strains over time and permitting the stronger strains to thrive.

· Water left standing in fields may help recharge shallow aquifers. Floodwaters may replenish water supplies in lakes and ponds.

· Floodwaters purge the rural (and sometimes urban) environment. This can have a major impact on public health. Some observers have noted that diarrheal diseases usually decline after widespread floods.

· Floods deposit sandbars that can be seeded to form barrier islands. These can be used to expand land area and as barriers against tropical storm surges.

· Floods deposit silts that can be “mined.” At a minimum, sand can be collected for construction. More important, the mud can be used for topsoil, construction, and landfill. Possibly they can be mined for important - often valuable - minerals.

In addition to the known benefits, there are many untapped benefits. Floods could be used as a source of energy, for example.

When is a flood disastrous?

Sometimes riverine floods are so big that their harm outweighs their benefits. The negative effects of flooding include death, property loss, a cumulative increase in personal and national debt, the increased incidence of certain diseases, soil erosion, sandcasting, the penetration of saltwater into soils and aquifers, the siltation of rivers and irrigation canals, and damage to and the destruction of public infrastructure, roads, railway beds, and other transportation.

If flooding usually occurs annually, what separates the normal, uneventful flood from a disastrous flood? Usually the magnitude of the flood. That magnitude can be measured as the number of people killed, the extent of the damages (physical and economic), the incidence of increased disease, and other factors. Usually floods classified as disastrous are defined by a combination of these criteria. But these criteria are subjective, representing mostly the views of urban or industrial observers. When do people who live in riverine areas call a flood disastrous?

In many societies, people distinguish between an inundation and a flood. In 1978, Unnayan, a Bengali rural development agency, worked with flood victims after massive floods in West Bengal, India. Cultivators they interviewed indicated that a flood has occurred when water remains in the field long enough to waterlog, when water strands or drowns livestock, when water currents scour the land, when floods deposit sand that cannot be economically removed, when floodwaters increase the salinity of fields, when water rises above the housing plains, when successive floods prevent immediate recovery, or when fish ponds are inundated and fry and fingerlings are swept away. For landless agricultural laborers, a destructive flood is one that reduces their job prospects or prevents them from going elsewhere in search of work. For nonfarm villagers, a flood is defined as water penetrating and damaging commercial buildings, water penetrating and damaging housing, or water preventing the transport of goods. Most rural people said that a flood was “when waters rose faster than one could take preventive measures,” a response which indicates that if more warning could be given, floods might not be so destructive. This response implies a degree of indigenous local flood preparedness (Sen 1978a).

Urban people could define floods similarly to nonfarm villagers, adding that when floods occur normal business is disrupted, schools are closed for excessively long periods, food and fuel are hard to get, and basic services (such as water supplies, electricity, and communications) do not function for long periods.

Governments usually classify floods according to the level of government infrastructure that has been damaged or destroyed, and the number of houses and communities affected. Infrastructure that could be damaged include roads, lifelines and critical facilities, public buildings, schools, and health facilities. Rural people may not need or expect extensive flood control measures. In urban areas, the public is likely to demand structural measures to prevent floodwaters penetrating the community.

As traditional rural society becomes more modem and urbanized, there will be substantially more nonfarm-, nonfishing-, and nonriver-based labor and a corresponding expansion of costly infrastructure that is not inherently flood-resistant. Even in rural areas, the number of villagers not directly involved in agriculture, who do not benefit from flooding, is likely to increase rapidly. So there is a steadily growing constituency for flood control. This constituency - because it is predominantly urban and influential and represents a substantial proportion of heavy investment in the country - is often more effective at advocating flood control than its opponents are at advocating the living-with-floods strategy.

Many governments have a problem weighing the net benefits of floods against the relative cost and benefits of trying to prevent or control them. The negative effects of flood control measures - especially environmental or ecological changes they may cause - are often hard to predict so they should not be taken lightly or rushed into immediately after a particularly damaging flood. Flood control works require intensive study, and proposals must be accepted by all sectors of society before they are implemented.

Adapting to floods

Over the centuries, many societies have developed complex adjustments to floods. These adjustments and their role in riverine ecology should be the starting point for understanding alternatives to costly flood control works.

Adaptations to floods are most visible in the built environment, especially in housing and buildings. Common adaptations include: building houses on stilts so floodwaters can pass underneath, building houses on plinths or platforms so they are raised above flood levels, and building escape areas under roofs.

Siting is important in flood avoidance. Some societies have taboos against building certain forms of structures in known floodplains. In India, for example, the ancient Hindu building code, the Vastu Shastra, mandates that structures in coastal areas should be circular with conical roofs - a good design to resist floods and high winds. Traditional architecture usually adapts to flooding in the selection of timber, the design of the house’s base or foundation, and the building’s orientation to the flow of floodwaters. Human settlements are often collective expressions of these adaptations - for example, villages built on artificial platforms or areas raised above flood level, canal villages, artificial islands, floating villages or settlements, and settlements built on flood control embankments. Even cities adapt to floods; the most famous is Venice, Italy. More commonly, sections of cities adapt to floods by building floating settlements or stilt housing in flood-prone areas.

That regions can come to grips with floods without massive flood control works is evident in some of Thailand’s lower delta. Houses there are raised on stilts, roads generally run parallel to the rivers, and, where they cross the watershed, massive culverts permit the water to flow through without backing up. Floods occur every year, but are only rarely damaging. The region has adapted to the environment.


Riverine economies must adapt to floods in every facet of the economy from agriculture to industry, from the selection of crops to the selection of tools, transport, and conveyances.

Most riverine economies are agriculture-based. The crops selected, such as rice, usually depend on large quantities of water. Integrated cropping of grains and such long-stem water perennials as jut or reeds provides additional income and serves as insurance against flood losses.

Some crop varieties show a natural resistance to floods. The longer-grain natural varieties of rice fared much better in the 1988 floods in Bangladesh than the hybrid high-yielding varieties (HYVs). Farmers whose paddy stems were knocked over and waterlogged in the floods simply broke the stems at the internodes and watched them regenerate in time to produce a crop only slightly less abundant than normal. HYVs had to be plowed under and replanted.

Cultivators in deltas have become familiar with backup strategies to counter flood losses: selecting flood-resistant varieties, most often, and planting alternative postflood crops. In Viet Nam’s Mekong delta, farmers keep a reserve stock of potato seeds to plant quickly after a flood, using the water hyacinth tailings that floodwaters usually deposit on their fields as a mulch for the seedlings. Rural economies often adjust naturally to a flood. After the 1988 floods in Bangladesh, farmers whose standing paddies were affected by the floods could still collect the stunted stems and sell them as fodder for livestock. So much fodder was lost that prices for the salvaged stalks were almost equal to prices for harvested paddies (UNDP 1989b).

Fishing is always important in riverine economies. Casual fishing in local streams gives families an additional source of protein and an alternative or supplemental income. More important for the general economy, many people in riverine economies normally engage in professional fishing or fishing-related enterprises. Lakes or ponds used for fishing rely on floods to periodically replenish natural stocks of fingerlings.

The most important forms of transport in riverine areas are boats, barges, and rafts - craft that are inherently flood-resistant. In floods, other types of transport usually come to a halt, but river people usually have enough boats to remain mobile. In the Philippines, people often use the floods to float bamboo and forest products, such as logs, downstream to markets that otherwise could not be reached economically. In Bangladesh, people who live some distance from the rivers put goods they have prepared during the year on rafts and take advantage of the floods to transport them to the principal streams for collection and sale in large markets.

People also use floods to replenish drinking and irrigation water supplies. Researchers working in India in 1982 noted that villagers often view flood warning as a signal to intercept and impound floodwater for use on crops, holding back as much water as possible to raise a dry season crop - particularly in areas where short floods are common (Schware 1982a).


Most riverine societies have not only developed ways to live with and use floods, but have developed responses for avoiding the unusually large events. It is important to identify these measures as they are a clue to where to begin developing a national flood preparedness strategy. As a flood season nears, most riverine people instinctively take certain precautions: moving valuables to higher places in their shelters, moving animals to higher grazing areas or farther from the river, repairing boats, building rafts, and replacing the parts of their houses that have weathered and deteriorated.

Traditional warning systems

Many riverine societies have developed warning systems to give people enough notice to evacuate their homes and find shelter from floods. These systems may appear to be loosely organized, but in practice have been effective for disseminating basic warnings over wide areas. Often a variety of long-established message networks function at the same time, providing mutually supporting messages that condition people’s responses. At one level, people observe such natural cues as old flood markers inscribed on trees or ants moving their eggs to higher ground. At another level, they set up a network of voluntary river watchmen and embankment patrols.

Important research on traditional warning systems has been carried out in Bengal, India. In 1980-82, the National Center for Atmospheric Research (in Boulder, Colorado), in a series of studies on flood warning messages, identified socioeconomic constraints on the effectiveness of the official warning system and compared it to the traditional “folk” system. The researchers concluded that the official machinery for disseminating warning messages in the Damodar Valley was jeopardized by mechanical shortcomings and a communication network that was not ideal for communicating to many people widely dispersed in remote villages. They saw grounds for reappraising the official approach to flood warnings. They found that some problems could be met by applying appropriate technologies; others required better coordination of information, to prevent unnecessary time lags; still others called for more awareness of the needs of people who might use the information system (Schware 1982a).

Folk systems adapt to modem times. In India, for example, villagers near police stations that are linked to national police radio networks often make a point of sending someone to the police station several times a day to get the latest radio reports of upstream news on flooding. If there are reports of flooding, the person returns and warns the village. Warnings can be disseminated in many ways. In Indochina, fireworks are often used to alert people that flood notices have been posted. Flags are used in some Philippine and Indonesian communities, among others. In Latin America the ringing of church bells is a common flood warning.

The installation of embankments sometimes undermines these “folk” systems. People believe that the embankments prevent floods, so that there is no reason to maintain the traditional system. Where embankments provide only limited protection from flooding or where they are routinely breached or cut, the abandonment of folk warning systems has left communities with no suitable warning system. 1

Human responses to flood warnings

How people perceive and respond to flood warnings depends on available options in terms of a particular site, their economic needs, their health, and available information (Schware 1982). Sometimes people can only move to the nearest higher ground - for example, to rooftops, embankments, roads, railway lines, or even trees. Economic factors also come into play. Villagers tend to leave their homes only as a last resort if they believe that thieves in boats will steal their belongings. They cannot afford to leave behind their few tools and household possessions. Often they build rafts of bamboo or banana stems, tie them to a nearby tree, and stay on the rafts until flood-waters subside. Moving to roads or embankments is the next most common evacuation measure. Generally people avoid community shelters. Few can accommodate many people with adequate food and sanitation. Studies of flood shelters in India found that villagers overwhelmingly shun this option unless absolutely necessary.

Knowing about these typical responses is important for two reasons. First, it is doubtful that the longer lead times made possible by high-tech warning systems (radar, remote sensing, and the like) will significantly affect evacuation behavior in the near term. Second, the costly construction of dedicated flood shelters will not significantly reduce deaths and may be a waste of resources.

Traditional recovery strategies

Recovery begins with people’s efforts to salvage what remains of crops, tools, and personal belongings. If the family has livestock, a first task is to acquire fodder. Approaches to flood recovery depend on the type of crop, season, and so forth. For example, if it is the growing season, certain varieties of wheat can be cut where they have been bent by floodwaters and they will regenerate. Hybrid grains may not regenerate if waterlogged, but will often continue to grow and can be used for hay.

Flooding in riverine environments often increases crop production, especially when natural varieties are grown. After the massive 1988 floods in Bangladesh, the forecast was losses of 40 percent of the normal harvest - but the country actually produced 10 percent more rice than normal. Other staples also showed higher yields (USAID 1989).

Some strategies for economic recovery place a hardship on families - especially migration to find alternative sources of work. Traditionally, workers went to nearby communities to find seasonal work until they could accumulate enough resources to restart their own enterprises. But recent population increases may have saturated the postflood job market, forcing more people to go to large urban areas for wages.

Traditional mitigation measures

Living with the constant threat of floods forces people to take measures to mitigate losses should a damaging flood occur. Typical measures include:

· Adjusting planting and harvesting cycles. The most common method of flood mitigation is to adjust the crop cycle so that crops are already harvested by the time damaging floods are most likely. There are traditional guides for this practice and more recently farmers’ almanacs have been used to suggest planting dates (Brammer 1975).

· Seed banking. Farmers routinely hold back some seeds for replanting in case a flood early in the season destroys emerging crops.

· Famine crops. Many subsistence farmers set aside part of their land to grow flood-resistant crops that can be used for food if floods destroy the normal harvest (Campbell 1984).

· Mixing crops. Many farmers mix crop varieties (for example, HYVs with natural long-stem varieties) to reduce potential losses.

· Multiple fields. In some areas, farmers trade land to get fields at various elevations - with the objective of having at least one field that is less vulnerable to flooding. In Indonesia and the Philippines, village elders on some islands reapportion land annually to help farmers spread their risk.

· Alternative on-farm production. Many cultivators reduce their vulnerability by investing in other income-producing enterprises - most often, livestock, poultry (especially ducks), fishing, and the rental of draft animals. This is a much-favored mitigation strategy because the assets are movable.

· Informal “insurance,” cash pools, and the like. In Peru and elsewhere, farmers contribute cash to a common fund, or pool, as insurance against flood losses. If a cultivator loses his crop, he may borrow from the pool.

· Cooperatives (especially thrifts). Formal savings and loan coops, a recent innovation, provide cash to farmers in the event of a loss. Development agencies working with coops often encourage members to take collective mitigation measures.

Adapting traditional responses

The beginning point for any flood mitigation program should be to identify such traditional local responses to floods and incorporate them into the national strategy. The most important policy issue to be addressed in developing a national flood strategy is the tradeoff between structural and nonstructural measures. It may be technically feasible to control floods, but is the economic and ecological effect worth it? Do structural measures attract more people or economic activities onto floodplains where they should not locate? Does that produce long-term environmental problems? Will water tables or soils be affected?

Second, a government must decide whether it favors a centralized or decentralized planning and implementation model. Take Bangladesh, for example, where the area of potential flooding is staggering. As much as two-thirds of the land surface was covered by water in recent floods and as many as half of the people were said to be affected. With so much vulnerability, it is impossible for the government to meet all needs, so flood preparedness and mitigation measures must be selective and must rely on self-help and local initiative. What makes sense in Bangladesh is a community-based approach heavily oriented toward the adaptation of traditional responses.

To adapt traditional responses to official strategy means reorienting the planning process, to plan flood mitigation measures from the perspective of the communities most likely to be affected, and to involve villagers in local plans. Planning should be initiated at the village level and priority should be given to activities that stimulate self-reliance, promote cooperation and community involvement, and contribute to community development. Community development groups can play a major role in planning. Efforts should be made to involve local community development agencies and NGOs in the planning process, to improve coordination between these agencies and the government.


Flood mitigation proposals bring conflicting agendas into focus. Some cultivators may want their fields to be flooded and will take measures to ensure that they are. Not everyone appreciates flood control embankments. Breaches are often intentionally cut in levees - sometimes by people living between the levee and the river, in a desperate effort to lower the water on their side of the embankment; sometimes by cultivators who want to bring water, soil, or nutrients to their fields. People who benefit from floods - such as fishermen, brickmakers, and sand vendors - are also likely to oppose flood control.

Opposition also arises when land is expropriated for embankments. The average holding in many riverine areas is less than one hectare. An embankment could cover much of a plot and, in the process, thousands of small cultivators could be displaced or their land holdings reduced so much they are no longer profitable. In a country where demand for land is high, the political costs of embankments must be weighed carefully. In densely populated riverine areas, the best policy may be to limit embankments, permit controlled flooding, and emphasize community-based emergency preparedness and mitigation measures.

In any flood mitigation program, there are likely to be strong advocates of flood control and equally strong voices for “living with floods.” The voices for flood control are likely to be stronger. The constituency for flood control is primarily those who will be harmed the most by flooding or those who will benefit from flood control works. That includes threatened community groups, such as farmers living in low-lying, poorly-drained areas, nonfarm workers in villages, urban dwellers, and people whose livelihoods or income are affected. It also includes such members of the technical community as engineers, construction firms, builders and operators of infrastructure, and government ministries (such as agriculture, power, roads, and railways) whose projects or facilities are threatened. Other members of the constituency for flood control works include large landowners who will benefit from increased land area or irrigation and donors with investments in infrastructure, critical facilities, and projects in flood-prone areas.

Advocates for the “living with floods” approach are less powerful. They include groups with little representation in government, such as small subsistence cultivators, fishermen, and small craftsmen. Their support is normally from environmentalists, ecologists, and development workers - groups that traditionally lack political clout. It is this constituency that must ultimately be mobilized to support any nonstructural mitigation or preparedness efforts.

Flood mitigation efforts compete with other development projects for scarce resources. In any country - no matter what level of development - it is difficult to get disaster mitigation on the national agenda. It can only be justified if mitigation benefits long-term economic and community development. Thus disaster mitigation policy should be part of and should support general economic and social development.


One of the most important decisions to be made is where to place national responsibility for flood strategy. Designation of the responsible agency often determines how the program will be carried out. If an irrigation ministry is given the task, for example, there is likely to be more emphasis on structural flood control measures, such as embankments or engineering works. If the task is given to a high-level committee, the approach chosen may well reside with the committee’s technical staff. If responsibility is assigned to a relief authority, the focus will usually be only on immediate response and short-term disaster relief measures.

The lead agency should thus be carefully considered. Agencies with experience on this issue (such as UNDRO and USAID) in most cases recommend that a single agency be given responsibility for all pre- and postdisaster functions. If this is the course chosen, responsibility should be vested in a line ministry strong in operational capabilities (communications, equipment, and transport).

An alternative is to split responsibilities between ministries. The usual manner is to delegate responsibility for prevention and mitigation to a ministry with full-time responsibility for planning, construction, and maintenance of flood prevention and mitigation projects; then to delegate the relief and response function to a specialized relief or social service agency. The two then develop preparedness plans jointly and policy and coordination are handled by a high-level, interministerial committee chaired by a top government official.

This approach has some strengths. Comprehensive emergency management requires calling on specialties found in many different types of agencies. It is rare, and probably not even desirable, for all functions to be in one agency; the costs would be enormous. Recognizing the contributions each agency can make and developing the ability to coordinate and draw resources from them in an emergency is generally the most effective way to approach the matter.

Whatever agency is chosen, it is important that flood preparedness and mitigation efforts not be carried out in a vacuum. In most countries multiple hazards exist for which there are other disaster preparedness efforts. Many riverine areas are also subject to cyclones, for example. Efforts should therefore build upon any work already done for cyclone preparedness and mitigation; favor activities that support both cyclone and flood preparedness; and favor measures that build awareness of, and stimulate more effective response to, all major hazards.


In developing a national program, planners should keep in mind the types of local responses that can be improved with outside assistance. These include:

· Issuing warnings at the village level.

· Organizing working parties to repair embankments quickly and preempt breaches. This requires stockpiling materials locally in predetermined locations and developing ways to summon and mobilize the required number of workers on short notice.

· Organizing working parties to sandbag critical facilities. This also requires stockpiling supplies and mobilizing workers.

· Stockpiling and prepositioning tools and equipment to facilitate the relief and support of those who have been evacuated.

· Making transport arrangements so evacuation and relief can be speedy.

· Supporting agricultural recovery strategies, stockpiling information about practices to be followed, and prepositioning essential inputs that cannot be supplied by normal or postflood sources.

· Developing plans to provide emergency supplies of food and clean drinking water.


It is important that donors coordinate their support. A donors’ aid group can be formed for this purpose. The group should meet formally at least every two years to propose new projects and review progress. When any project is developed, the aid group as a whole can act as a project review committee, or at least a group of its members can serve on such a committee. An aid group serves two purposes. It shows that the donors treat the matter seriously and jointly support activities, and it serves as a bridge between old and new focuses when they change. Collectively, the group has more clout when it comes to taking corrective measures. The aid group could be made up of major donors, such as bilateral organizations, the UNDP, or the World Bank. But other interested groups - such as World Food Programme, UNICEF, World Health Organization, and the League of Red Cross and Red Crescent Societies - could also participate. To coordinate the donors’ inputs, a full-time disaster preparedness project officer should be appointed and supported with appropriate technical advice, as needed.

Several principles should guide project funding and planning. First, wherever possible, the donors should jointly finance projects. This signals - and ensures - that donor interest remains high. Second, priority should be given to projects that involve two or more ministries or departments. Ultimately, disaster response requires interministerial cooperation and coordination so it should begin in the preparedness phase. Finally, funding should involve local counterpart funds, where possible.

Program planning

Measures to prepare communities to minimize flood dangers involve flood mitigation and preparedness activities. Mitigation efforts aim to reduce a flood’s impact and prevent it from becoming a disaster. Some mitigation measures are structural, such as building platforms for villages or local embankments to control or diminish flooding. Most structural measures are individual actions such as reinforcing houses to make them more disaster-resistant or building houses on raised plinths above expected flood levels. Nonstructural measures, such as changing agricultural cropping patterns to reduce losses, involve changes in institutions, regulations, behavior, knowledge, and attitudes. For the most part, small-scale, self-help, and community-based measures are the main thrust of mitigation strategies.


The assumption underlying disaster preparedness is that a flood will strike a community and that the community - the people and institutions - should be prepared to deal with it. The focus is on saving lives, reducing property loss, and structuring the emergency response to be timely and to lay the groundwork for rapid recovery. Disaster preparedness for floods involve three kinds of activity: warning, evacuation, and flood-fighting.


Floods are one of the few forecastable natural hazards for which adequate warning can be given. The objective is to issue warnings as early as possible so people can protect their homes, belongings, and livelihoods, and then, if necessary, evacuate to a safe area. The essential elements of warning systems are vulnerability mapping, communications systems that reach the appropriate authorities in threatened communities, and methods of message dissemination that stimulate people to take effective safety measures.

Warning systems are crucial to “living with flood” strategies because people must have time to take action. National warnings systems often fail because of:

· Problems disseminating warnings locally, below the district level.
· Unclear “messages.”
· No viable response options by the time the message reaches the target communities.

In recent years, exceptional strides have been made in improving warning and evacuation systems, based on behavioral studies and analyses of interpersonal communications. In rural areas, a national warning system is only as effective as the extent to which it builds on the traditional warning system and extends communications to the villages. Warnings based on public radio broadcasts have not been effective in rural areas. National systems are usually more effective at warning urban communities, government institutions, public utilities, large industrial and commercial facilities, and emergency authorities. The centerpiece of rural systems should be local people who observe, interpret, and issue alerts - not the meteorological office. Emphasis should be given to:

· Improving locally generated warnings.

· Getting credible, respected local leaders to issue clear instructions about where to go.

· Arranging for the protection of livestock and movable assets.

· Providing or expanding nearby evacuation sites that meet rural people’s need for shelter, food, and the storage of livestock and personal effects.

· Using village-level evacuation transport appropriate to the environment.


Evacuation measures may include providing the transport needed to leave a threatened area quickly; rescuing stranded people; providing temporary shelter, food, water, and basic comforts; and then, when the emergency is over, helping people return to their homes. A successful evacuation, especially in riverine areas, requires detailed planning, identifying escape routes and shelter sites, training shelter managers, organizing rescue and transport teams, and prepositioning food and temporary relief items.


Flood-fighting involves measures taken during a flood to prevent or reduce damage to communities, public infrastructure, or critical facilities that might be caused by the overtopping or breaching of embankments, water rising too high, or water threatening areas because of changes in the course of streams, downstream blockage; and so forth. Flood-fighting usually involves building temporary embankments or small-scale plodders - principally by sandbagging - and making speedy repairs to flood control works. Flood-fighting requires stockpiling and prepositioning tools, materials, and equipment, and planning how to mobilize and support large work forces on short notice.

The most important - and most overlooked - function of preparedness is to structure the overall emergency response. This is usually carried out by means of an emergency action plan, standing orders for key ministries, or standard operating procedures (SOPs). Ideally, a preparedness plan is a series of subplans, including a warning plan, an evacuation plan, a search-and-rescue plan, an assessment plan, and an emergency response plan.

The whole premise of preparedness planning is that an emergency is not the time to be deciding what to do. During an emergency, information is incomplete, conflicting, and rarely accurate. The best time to make decisions is when they can be addressed rationally, without the pressures of time and urgency that force premature or incorrect decisions. The objective of disaster preparedness is to move decisionmaking forward - out of the emergency - and to predetermine as many of the decisions and responses as possible. Once the decisions are made, detailed plans can follow.


Many resources are essential to rapid recovery from floods. It is important to identify them and to increase people’s access to them in normal development projects. If planners can identify the usual postflood agricultural strategies that farmers use to mitigate their losses, for example, the government can be encouraged to provide the tools or inputs that will be needed locally to build up onsite reserves that could be tapped in an emergency to accelerate recovery and reduce costs. If alternative varieties of crops are grown, the seeds, fertilizers, and pesticides that increase yields can be provided in outlets near floodplains - and reserves can be kept on hand in case they are needed. Similarly, if certain implements are needed to salvage waterlogged crops, it may be possible to provide them through cooperatives, and to promote the practice of holding some in reserve at the coops for postflood use.

Distribution of relief supplies is more effective when people rely as little as possible on external mechanized transport and when local transport is emphasized - especially (in the riverine environment) local, or country, boats.

Concepts about what is needed and important in emergencies should be reevaluated, especially for shelter. It is almost as costly to deliver tents and plastic sheeting, for example, as to deliver galvanized iron roof sheets - a commodity of far more value to local people as it can be used first as a shelter and later in the replacement house.

Outline for developing a national program

A national program incorporating the recommendations suggested in this chapter should begin on two fronts simultaneously: at the community level, working from the bottom up, and at the national level, working from the top down.


Plans for community actions should originate at the grassroots level. District and national plans can be developed later to support the array of community plans.

(1) Identify traditional mitigation and preparedness measures. Begin by identifying the full range of local practices, evaluating their effectiveness, and determining ways they can be incorporated or expanded in national programs. Remember that people’s responses to floods are shaped by their perception of risks balanced by their perception of benefits. To motivate people to take action, proposals must address these perceptions. A starting point is thus to:

· Study perceptions of risk among different income and occupational groups in different areas, both rural and urban.

· Determine who is at risk. Not all communities are equally vulnerable to a flood. It is not possible or desirable to evacuate everyone or to extend protection to those who do not really need it, so vulnerability and risk mapping should be carried out. In the long term, detailed maps can be developed, using geographic information systems (GISs). In the short term, gross approximations can be made by examining recent flood experiences.

· Study the range of local responses, evaluating their effectiveness and determining ways they could be improved through government interventions. For example, yields of some alternative crops could be increased by timely provision of fertilizers, which could be stockpiled in strategic locations.

(2) Initiate village-level activities. Many activities and practices can be introduced and encouraged at the village level, including:

· Village-based warning and evacuation systems.

· Small-scale protective structures (such as village plinths and evacuation platforms).

· Protective measures for housing (such as water-resistant mud construction and treatment of structural timbers).

· Specific flood season agricultural practices.

· Planting bamboos or fast-growing trees that can be used for disaster-related purposes (such as rafts and components for temporary shelters).

(3) Promote economic development strategies that reduce vulnerability. This is one of the least-explored options. Measures that can be combined with other activities have a better chance of acceptance and implementation. For example, agricultural adjustments or innovations have a better chance of succeeding if they produce greater yields or profits than if they simply reduce a family’s exposure to risk - a risk that may not materialize in a given period. An inventory should be made of development programs and strategies that could have implications for disaster mitigation or preparedness.


While actions are being initiated at the community level, the following national and district-level program should also be under way:

· Evaluation of national and district-level emergency responses to past floods, and identification of lessons and areas where improvements are needed.

· Vulnerability and risk mapping.

· Development of warning systems.

· Development of evacuation and sheltering systems.

· Improvement of communications systems.

· Development of model plans that can be adapted to community needs and can serve as a basis for initiating mitigation and preparedness activities at the village level.


1. People intentionally cut embankments for many reasons. A UNDP study of the 1988 Bangladesh floods found that squatters who live between an embankment and the river cut the embankment when floods come hoping to lower the flood level. Some farmers behind an embankment cut it to flood their fields, water their crops, or bring nutrients to their fields. Some people want to flood ponds to recharge them and replenish fish stock.