Floods in Russia and Central and Eastern Europe are leaving behind a trail of devastation, with some 100 dead and billions of dollars in damages. Some of those who lost most or all of their property to the waters have criticized the authorities' inability to forecast the extent of the floods and to act in advance to limit the destruction. But meteorologists and hydrologists alike say that despite advances in weather technology, forecasting such catastrophes far in advance remains difficult, since it depends on many variables, such as the volume of rainfall and the size of river basins.
Prague, 21 August 2002 (RFE/RL) -- Hundreds of thousands of people in Central and Eastern Europe were evacuated in a rush last week ahead of record floods on several rivers in the region.
In the Czech capital, Prague, the German city of Dresden, and numerous smaller cities, tens of thousands of residents in districts threatened by the rising waters were hurried out of their homes without prior notice. In Prague, authorities even had to warn that they would use "reasonable force" to remove residents who refused to leave endangered buildings.
In the wake of the disaster, some of those who lost many or all of their possessions in the deluge are criticizing the authorities for acting too late or making incorrect estimates about the severity of the floods.
In Germany, after the swollen Elbe swept through Dresden, angry residents said local authorities for years had ignored warnings that flood protection was inadequate in the region.
In the Czech Republic, Prague Mayor Igor Nemec came under fire for giving confusing statements about the magnitude of the rising waters. Nemec first said on 12 August that water levels in the city would only reach a 20-year high, before upping his estimate to a 50-year high. The following day, the Vltava (Moldau) reached a level unseen in at least 100 years, flooding parts of Prague's historic center and neighboring districts and prompting the last-minute evacuation of many inhabitants.
Nemec, in statements published in Czech newspapers today, blamed the late notification of evacuations on what he called "wrong and poor" reports from water-resources managers for the Vltava basin.
But meteorologists and hydrologists alike say that despite technological advances, forecasting torrential rains and inundations early enough to prevent widespread damage and loss of life remains difficult.
Catherine Senior, a researcher at Britain's Hadley Center for Climate Prediction and Research, says climatologists are working on long-term projections of changes in European temperature and precipitation up to 100 years in advance.
But Senior told RFE/RL that, although progress is obvious in computerized weather forecasting, predicting extreme weather remains almost impossible. "Making predictions for extreme events such as the things that have recently occurred over Central Europe is quite difficult. By their very nature, they are quite rare events, and it's difficult for us to know whether the sort of changes that we're seeing are due to climate change, for example, or just part of the natural variability of the climate. The predictions that we make for changes in, for example, rainfall are increasingly improving, and we're getting more and more accurate. But there's no doubt that there are still problems with some of the predictions. We are trying to improve our computer models all the time, and certainly I would say that these sort of [longer-term] predictions are becoming more accurate," Senior said.
Senior said analyses of computer models suggest a recent increase in extreme events. But she said it is not yet clear whether the increase can be linked to a global warming of the Earth's climate or is simply due to such events having been more accurately recorded in recent times.
Hydrologists, in turn, say that in the case of long rivers, earlier and more accurate forecasts of flood crests are easier because precise hydraulic measurements can be made and transmitted with relative speed downstream.
Arthur Askew, director of the Hydrology and Water Resources Department at the United Nations World Meteorological Organization (WMO), told RFE/RL that on rivers such as the Danube, the flows can be known a few days in advance, at least.
Indeed, capitals on the Danube such as Bratislava, Vienna, and Budapest escaped the current floods largely unscathed thanks to preparations made several days before the water crested.
But Askew said it is sudden rainfall in the basins of small and medium-sized rivers, such as the Vltava or Elbe, that is more dangerous because it is difficult for meteorologists to anticipate. "If you take medium-sized river basins, then in order to get good advance notice you have to know what the rainfall was, and therefore you need the meteorologist to come into the story and say this is what the rainfall was. If you have smaller river basins -- and these are a real problem in many cities where very small streams can suddenly become raging torrents -- you need to even forecast in advance what the rainfall will be, and that is a very difficult thing for the meteorologist to do on [this] sort of small scale," Askew said.
Hydrologists also point to the fact that torrential rains turn into devastating floods faster in river basins that have been subjected to massive human alteration. Often, developments that are done for economic reasons, such as obtaining more agricultural land and improving navigation, have the side effect of worsening floods.
Deforestation on mountain slopes means that water from torrential rainfall meets no natural obstacles on its way down, while rivers whose courses have been straightened and turned into navigable canals act as natural "water slides" for torrents, accelerating their speed. Hence, the time for flood preparations downstream is becoming shorter, while the volume of runoff increases.
However, Askew said catastrophic floods, although part of nature's cycle, are rare and unpredictable events. Askew said he is against building expensive protection systems against floods that might not repeat for many years to come.
Instead, he told RFE/RL that funds should be spent on better data collection and sharing, as well as on research to improve the accuracy of weather forecasts. "If you divert all the funds to protecting those lands against an event which is very extreme and in general, unusual, those funds may be better used elsewhere. So, above all, work should go into collecting the data and the information, improving the forecasting systems -- they can always be improved -- so that in the long term, we can make better estimates of the likelihood of these occurring, and in the short term, when the heavy rains come, we can make better forecasts of what will happen in the next few hours and days to allow people to be evacuated and property to be saved," Askew said.
Meteorologist Catherine Senior believes totally accurate weather forecasts are impossible. But she agrees that scientists can help establish a more accurate longer-term weather pattern to contribute to efforts against catastrophic floods. "It's never going to be possible, I think, to predict when any one particular event will occur down to the nearest week, for example. So we will have to be prepared in a more general way, so that when an event like this does occur, we have the processes and procedures to enable us to react quickly. But I think our role, as climate predictors, is to say whether we think that these events are likely to become more frequent in the future and give that information to people to make the [most] appropriate planning that they can do," Senior said.
Senior also said that scientists now have what she called "strong evidence" that human activities are leaving a fingerprint on the Earth's climate, and that more attention is needed to prevent its further alteration.
Prague, 21 August 2002 (RFE/RL) -- Hundreds of thousands of people in Central and Eastern Europe were evacuated in a rush last week ahead of record floods on several rivers in the region.
In the Czech capital, Prague, the German city of Dresden, and numerous smaller cities, tens of thousands of residents in districts threatened by the rising waters were hurried out of their homes without prior notice. In Prague, authorities even had to warn that they would use "reasonable force" to remove residents who refused to leave endangered buildings.
In the wake of the disaster, some of those who lost many or all of their possessions in the deluge are criticizing the authorities for acting too late or making incorrect estimates about the severity of the floods.
In Germany, after the swollen Elbe swept through Dresden, angry residents said local authorities for years had ignored warnings that flood protection was inadequate in the region.
In the Czech Republic, Prague Mayor Igor Nemec came under fire for giving confusing statements about the magnitude of the rising waters. Nemec first said on 12 August that water levels in the city would only reach a 20-year high, before upping his estimate to a 50-year high. The following day, the Vltava (Moldau) reached a level unseen in at least 100 years, flooding parts of Prague's historic center and neighboring districts and prompting the last-minute evacuation of many inhabitants.
Nemec, in statements published in Czech newspapers today, blamed the late notification of evacuations on what he called "wrong and poor" reports from water-resources managers for the Vltava basin.
But meteorologists and hydrologists alike say that despite technological advances, forecasting torrential rains and inundations early enough to prevent widespread damage and loss of life remains difficult.
Catherine Senior, a researcher at Britain's Hadley Center for Climate Prediction and Research, says climatologists are working on long-term projections of changes in European temperature and precipitation up to 100 years in advance.
But Senior told RFE/RL that, although progress is obvious in computerized weather forecasting, predicting extreme weather remains almost impossible. "Making predictions for extreme events such as the things that have recently occurred over Central Europe is quite difficult. By their very nature, they are quite rare events, and it's difficult for us to know whether the sort of changes that we're seeing are due to climate change, for example, or just part of the natural variability of the climate. The predictions that we make for changes in, for example, rainfall are increasingly improving, and we're getting more and more accurate. But there's no doubt that there are still problems with some of the predictions. We are trying to improve our computer models all the time, and certainly I would say that these sort of [longer-term] predictions are becoming more accurate," Senior said.
Senior said analyses of computer models suggest a recent increase in extreme events. But she said it is not yet clear whether the increase can be linked to a global warming of the Earth's climate or is simply due to such events having been more accurately recorded in recent times.
Hydrologists, in turn, say that in the case of long rivers, earlier and more accurate forecasts of flood crests are easier because precise hydraulic measurements can be made and transmitted with relative speed downstream.
Arthur Askew, director of the Hydrology and Water Resources Department at the United Nations World Meteorological Organization (WMO), told RFE/RL that on rivers such as the Danube, the flows can be known a few days in advance, at least.
Indeed, capitals on the Danube such as Bratislava, Vienna, and Budapest escaped the current floods largely unscathed thanks to preparations made several days before the water crested.
But Askew said it is sudden rainfall in the basins of small and medium-sized rivers, such as the Vltava or Elbe, that is more dangerous because it is difficult for meteorologists to anticipate. "If you take medium-sized river basins, then in order to get good advance notice you have to know what the rainfall was, and therefore you need the meteorologist to come into the story and say this is what the rainfall was. If you have smaller river basins -- and these are a real problem in many cities where very small streams can suddenly become raging torrents -- you need to even forecast in advance what the rainfall will be, and that is a very difficult thing for the meteorologist to do on [this] sort of small scale," Askew said.
Hydrologists also point to the fact that torrential rains turn into devastating floods faster in river basins that have been subjected to massive human alteration. Often, developments that are done for economic reasons, such as obtaining more agricultural land and improving navigation, have the side effect of worsening floods.
Deforestation on mountain slopes means that water from torrential rainfall meets no natural obstacles on its way down, while rivers whose courses have been straightened and turned into navigable canals act as natural "water slides" for torrents, accelerating their speed. Hence, the time for flood preparations downstream is becoming shorter, while the volume of runoff increases.
However, Askew said catastrophic floods, although part of nature's cycle, are rare and unpredictable events. Askew said he is against building expensive protection systems against floods that might not repeat for many years to come.
Instead, he told RFE/RL that funds should be spent on better data collection and sharing, as well as on research to improve the accuracy of weather forecasts. "If you divert all the funds to protecting those lands against an event which is very extreme and in general, unusual, those funds may be better used elsewhere. So, above all, work should go into collecting the data and the information, improving the forecasting systems -- they can always be improved -- so that in the long term, we can make better estimates of the likelihood of these occurring, and in the short term, when the heavy rains come, we can make better forecasts of what will happen in the next few hours and days to allow people to be evacuated and property to be saved," Askew said.
Meteorologist Catherine Senior believes totally accurate weather forecasts are impossible. But she agrees that scientists can help establish a more accurate longer-term weather pattern to contribute to efforts against catastrophic floods. "It's never going to be possible, I think, to predict when any one particular event will occur down to the nearest week, for example. So we will have to be prepared in a more general way, so that when an event like this does occur, we have the processes and procedures to enable us to react quickly. But I think our role, as climate predictors, is to say whether we think that these events are likely to become more frequent in the future and give that information to people to make the [most] appropriate planning that they can do," Senior said.
Senior also said that scientists now have what she called "strong evidence" that human activities are leaving a fingerprint on the Earth's climate, and that more attention is needed to prevent its further alteration.
