UN Chronicle | We May Know in 2100: What Caused the Floods of 2002?

We May Know in 2100
What Caused the Floods of 2002?

Article

Throughout the world at any time, a river somewhere is in flood and its waters are threatening communities, their properties and even their lives. Few of these events are reported due to their local impact. However, the floods in Central Europe and China have drawn international attention.

Floods in more than 80 countries have caused hardship for more than 17 million people worldwide since the beginning of 2002, according to the World Meteorological Organization (WMO). Almost 3,000 people have lost their lives, while property damage has amounted to over $30 million. The total area affected is over 8 million square kilometres, almost the size of the United States.

UN Photo

At the other end of this extreme water overload are droughts that have been and are still taking place around the world. Serious droughts are occurring in the Southern African Development Coordination (SADC) countries of southern and central Africa, resulting in starvation and a global outcry for food aid. In North America, over 37 per cent of the United States is suffering from severe drought, with the longest-lived in the southeastern States. At the same time, since mid-June 2002, much of Europe has received between 200 and 500 millimetres of rain; between 100 and 400 mm fell within a few days from England southeastward to the Black Sea. In China, as in Europe, the months of June and July were very wet.

In Europe, the Danube exceeded the previous highest recorded level by 3 centimetres in Budapest, by 22 cm in Komaron and by 30 cm in Esztergom. The Vltava and the Elbe were flooded to levels only expected to occur every 250 to 500 years. In China, the Xiangjiang, Xijiang and Yangtze rivers flooded large tracts of land in the southern part of the country. The flooding of Lake Dongting was caused by extremely heavy rain falling on already saturated land. The intensity of the rain in some locations has even been assigned a return period of 1,000 years. The result has been another major flood descending on the Yangtze River and flowing into Lake Dongting. And just last year in East Africa, floods disrupted life in a number of countries, and waters entered the premises of the United Nations Mission in Ethiopia and Eritrea (see photograph at left taken by a staff member). We cannot say whether these floods were associated with climate change. We will only be able to do so when we put these events in the overall context of the twentieth and twenty-first centuries. What we can say, however, is that there is already evidence of increasing precipitation in Northern Europe, and the Intergovernmental Panel on Climate Change (IPCC), established in 1983 by WMO and the United Nations Environment Programme, is confident in predicting increased flooding in the future. Certainly, upstream changes in land use and river "improvements", which were made for good economic and social reasons, would have caused some increase in the flood peak and speeded its arrival downstream. But these effects are likely to have been negligible in comparison with the following simple facts:

the upstream river basins were already saturated from earlier rains;

there was a series of very heavy storms with large, in some cases record, amounts of rainfall;

large volumes of water flowed downstream and, with nowhere else to go, occupied or tried to occupy their natural flood plains, and in the case of the Yantze, its natural overflow lake;

hundreds of years of development have led to the occupation of these banks and flood plains by housing, industrial and commercial properties, and agricultural activities, because they represent a valuable resource of flat land and alluvial soil.

The WMO national counterparts—the National Hydrological Services of the countries concerned—are analyzing the events to advise Governments on how to guard against natural disasters of this nature. The investment in the flood plains is so large and of such great historical importance that there can be no question of relocating elsewhere. Yet, these floods are natural phenomena that will certainly occur again and, whenever they do, whether in a matter of months or years or decades, these areas will once again be under threat. Flood management must be integrated with management of the plains and upstream catchment areas from which the waters flow and with decisions on whether to try to store or divert the floodwaters upstream. But they cannot be taken hastily because they must take into account the full impact of each measure, including the need to manage river flows in times of drought as well as floods. The link between floods and droughts is important. They are the two extremes of the same constantly varying environment in which we live and with which we must learn to live in harmony. We cannot stop droughts from occurring, but we can diminish their impact by understanding the normal precipitation and its seasonal and annual variability, through improved water management and land usage consistent with the precipitation in an area, and by ensuring that local communities, cities and States are developing and implementing contingency planning for precipitation deficit and drought situations—a world where cyclones bring drama without tragedy and floods drench landscapes without washing away promise.

Numbers of Great Natural Disasters Per Year, 1950-2001

Source: Munich Re 2001, taken from the Global Environment Outlook 3, published by the UN Environment Programme.

Graph shows increasing trends in frequency of "great" natural disasters. Catastrophies are classed as great if the ability of the region to help itself is overtaxed, making interregional or international assistance necessary, as is usually the case when thousands of people are killed, hundreds of thousands made homeless or when a country suffers substantial economic losses.

Living … With, At and In Risk

The United Nations has launched a global review on disaster reduction initiatives—Living With Risk—a 400-page study of the lessons learned by experts and communities in response to hazards presented by natural forces—volcanoes, fires, hurricanes, tsunamis, landslides and tornadoes—technological accidents and environmental degradation. In the last decade, 4,777 natural disasters have taken more than 880,000 lives, affected the homes, health and livelihoods of 1.88 billion people, and inflicted economic losses of around $685 billion on the world’s economies.

Living With Risk examines the lessons of the United Nations International Decade for Natural Disaster Reduction, which ended in 1999. It studies the traditional solutions that for centuries protected communities in various parts of the world against flood, windstorm, fire or drought, and examines the new pressures created by the explosive growth of cities.

The review looks at the ways in which political imagination and better communication have already begun to save lives and build hope for the developing nations. It examines the intricate links between economic development and environmental insecurity, calling for simple steps like risk assessment, warning mechanisms and public safety to be built into all development planning for the future.

"One of the most important demanding challenges when dealing with disaster reduction is that while action or investment should help to solve a community’s immediate needs, it must at the same time reduce any risks from catastrophe. This is especially important in countries where development is a survival issue", said Sálvano Briceño of the United Nations inter-agency secretariat of the International Strategy for Disaster Reduction, launched in 2000.
(For full report, please access www.unisdr.org)

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