Seminární práce na téma Sucho Pavel Stibor AMVT

Co je to sucho? Neexistuje žádná přesná akceptovaná definice sucha. Obecně řečeno – nedostatek dešťových srážek oproti dlouhodobému průměru v dané oblasti, během delší časové periody (obvykle několik měsíců nebo déle), mající dopad na lidské potřeby, životní prostředí. less rainfall than is expected over an extended period of time, usually several months or longer. Or, more formally, it is a deficiency of rainfall over a period of time, resulting in a water shortage for some activity, group, or environmental sector. Very generally, it refers to a period of time when precipitation levels are low, impacting agriculture, water supply, and wildfire hazard

Rozdělení sucha Meteorologické Zemědělské Hydrologické Socioekonomické Drought warning is further complicated by the existence of different types of drought. A meteorological drought may be identified first because of a lack of directly measured precipitation. On the other hand, socioeconomic drought is based on the premise that demand has outpaced the supply of water. Thus, a meteorological drought does not necessarily mean that there is also a socioeconomic drought (if supply is still meeting demand).

Meteorologické sucho Je obvykle srážková odchylka od normálu během delší časové periody. Definice sucha jsou specifické pro dané oblasti. Když mluvíme o suchu obecně, myslíme tím obvykle sucho meteorologické. Meteorological drought is usually an expression of precipitation’s departure from normal over some period of time. These definitions are usually region-specific, and presumably based on a thorough understanding of regional climatology. The variety of meteorologic definitions from different countries at different times illustrates why it is folly to apply a definition of drought developed in one part of the world to another: United States (1942): less than 2.5 mm of rainfall in 48 hours Great Britain (1936): 15 consecutive days with daily precipitation totals of less than .25 mm Libya (1964): annual rainfall less than 180 mm India (1960): actual seasonal rainfall deficient by more than twice the mean deviation Bali (1964): a period of six days without rain

Zemědělské sucho Nastává, když není dostatečně vlhká půda na to aby úroda v dané období pokryla lidské požadavky. Zemědělství je obvykle prvním ekonomickým sektorem postiženým suchem. occurs when there isn’t enough soil moisture to meet the needs of a particular crop at a particular time. Agricultural drought happens after meteorological drought but before hydrological drought. Agriculture is usually the first economic sector to be affected by drought.

Hydrologické sucho Hydrologické sucho nastává, když klesají zásoby povrchové a podpovrchové vody (vysychají vodní rezervoáry, prameny, studně). Krátkodobé deště nestačí k doplnění zásob vody. Projeví se až za několik měsíců po zemědělském suchu. Hydrologic indicators appear when surface and subsurface water supplies are below normal. As dry spells drag on, reservoirs drop and streams and wells dry up. Short-term rainfall usually isn't enough to replenish these water supplies. It takes longer for precipitation deficiencies to show up in components of the hydrological system such as soil moisture, streamflow, and ground water and reservoir levels. As a result, these impacts are out of phase with impacts in other economic sectors. For example, a precipitation deficiency may result in a rapid depletion of soil moisture that is almost immediately discernible to agriculturalists, but the impact of this deficiency on reservoir levels may not affect hydroelectric power production or recreational uses for many months. Also, water in hydrologic storage systems (e.g., reservoirs, rivers) is often used for multiple and competing purposes (e.g., flood control, irrigation, recreation, navigation, hydropower, wildlife habitat), further complicating the sequence and quantification of impacts. Competition for water in these storage systems escalates during drought and conflicts between water users increase significantly.

Socioekonomické sucho Nastává když sucho začne ovlivňovat přímo lidi (voda na příděl, nebezpečí požárů, hydroelektrárny nefungují = vyšší ceny za elektřinu). This category refers to the situation that occurs when physical water shortage begins to affect people. Long-term droughts go beyond dead lawns. Water rationing, wildfire threats and higher hydroelectric power bills are more likely. For example, in Uruguay in 1988–89, drought resulted in significantly reduced hydroelectric power production because power plants were dependent on streamflow rather than storage for power generation. Reducing hydroelectric power production required the government to convert to more expensive (imported) petroleum and stringent energy conservation measures to meet the nation’s power needs.

Co je to klima, klimatologie? Klima je obvykle definováno jako co je očekáváno nebo „normální“ a representuje každodenní počasí během delší časové periody (obvykle 30-ti letý průměr). Klimatologové se snaží objevit a vysvětlit dopady klimatu, aby společnost mohla plánovat své aktivity, navrhovat stavby, infrastrukturu a očekávat nepřátelské projevy klimatu. Klima je definováno stejně jako počasí teplotou, srážkami, větrem a slunečním zářením. Climate is usually defined by what is expected or “normal”, which climatologists traditionally interpret as the 30-year mean A climatologist attempts to discover and explain the impacts of climate so that society can plan its activities, design its buildings and infrastructure, and anticipate the effects of adverse conditions. Although climate is not weather, it is defined by the same terms, such as temperature, precipitation, wind, and solar radiation. Specifically, climatology answers crucial questions such as: How often does drought occur in this region? How severe have the droughts been? How widespread have the droughts been? How long have the droughts lasted? Examining water supplies and understanding the impact of past droughts help planners anticipate the effects of drought: What would happen if the drought of record occurred here now? Who are the major water users in the community, state, or region? Where does our water supply come from and how would the supplies be affected by a drought of record? What hydrological, agricultural, and socioeconomic impacts have been associated with the various droughts? How can we prepare for the next drought of record?

Ukazatele sucha Percent of Normal Standardized Precipitation Index Palmer Drought Severity Index Crop Moisture Index Surface Water Supply Index Reclamation Drought Index Deciles Percent of Normal The percent of normal precipitation is one of the simplest measurements of rainfall for a location. 2 Analyses using the percent of normal are very effective when used for a single region or a single season. Percent of normal is also easily misunderstood and gives different indications of conditions, depending on the location and season. It is calculated by dividing actual precipitation by normal precipitation -- typically considered to be a 30-year mean -- and multiplying by 100%. This can be calculated for a variety of time scales. Usually these time scales range from a single month to a group of months representing a particular season, to an annual or water year. Normal precipitation for a specific location is considered to be 100%. Because of the variety in the precipitation records over time and location, there is no way to determine the frequency of the departures from normal or compare different locations. This makes it difficult to link a value of a departure with a specific impact occurring as a result of the departure, inhibiting attempts to mitigate the risks of drought based on the departures from normal and form a plan of response (Willeke et al. 1994). Standardized Precipitation Index (SPI) The understanding that a deficit of precipitation has different impacts on the ground water, reservoir storage, soil moisture, snowpack, and streamflow led McKee et al. (1993) to develop the Standardized Precipitation Index (SPI). The SPI was designed to quantify the precipitation deficit for multiple time scales. These time scales reflect the impact of drought on the availability of the different water resources. Soil moisture conditions respond to precipitation anomalies on a relatively short scale, while ground water, streamflow, and reservoir storage reflect the longer- term precipitation anomalies. For these reasons, McKee et al. (1993) originally calculated the SPI for 3-, 6-,12-, 24-, and 48- month time scales. Overview: The SPI is an index based on the probability of precipitation for any time scale. Who uses it: many drought planners appreciate the SPI's versatility Pros: the SPI can be computed for different time scales, can provide early warning of drought and help assess drought severity, and is less complex than the Palmer Cons: values based on preliminary data may change Developed by: Tom McKee, et al., Colorado State University, 1993 Monthly maps: http://drought.unl.edu/watch/watch.htm, and http://www.wrcc.dri.edu/spi/spi.html Palmer Drought Severity Index (PDSI) In 1965, Palmer developed an index to measure the departure of the moisture supply (Palmer 1965). Palmer based his index on the supplyand- demand concept of the water balance equation, taking into account more than just the precipitation deficit at specific locations. The objective of the Palmer Drought Severity Index (PDSI), as this index is now called, was to provide measurements of moisture conditions that were standardized so that comparisons using the index could be made between locations and between months (Palmer 1965). Overview: The Palmer is a soil moisture algorithm calibrated for relatively homogeneous regions Who uses it: many U.S. government agencies and states rely on the Palmer to trigger drought relief programs Pros: the first comprehensive drought index developed in the United States Cons: Palmer values may lag emerging droughts by several months; less well-suited for mountainous land or areas of frequent climatic extremes; complex, has an unspecified, built-in time scale that can be misleading Developed by: W.C. Palmer, 1965 Weekly maps: http://www.cpc.ncep.noaa.gov/ products/analysis_monitoring/ regional_monitoring/palmer.gif The Palmer Index varies roughly between -6.0 and +6.0. Palmer arbitrarily selected the classification scale of moisture conditions based on his original study areas in central Iowa and western Kansas (Palmer 1965). Ideally, the Palmer Index is designed so that a -4.0 in South Carolina has the same meaning in terms of the moisture departure from a climatological normal as a -4.0 in Idaho (Alley 1984). The Palmer Index has typically been calculated on a monthly basis, and a long-term archive of the monthly PDSI values for every Climate Division in the United States exists with the National Climatic Data Center from 1895 through the present. In addition, weekly Palmer Index values (actually modified PDSI values) are calculated for the Climate Divisions during every growing season Crop Moisture Index (CMI) The Crop Moisture Index (CMI) uses a meteorological approach to monitor week-toweek crop conditions. It was developed by Palmer (1968) from procedures within the calculation of the PDSI. Whereas the PDSI monitors long-term meteorological wet and dry spells, the CMI was designed to evaluate shortterm moisture conditions across major crop producing regions. It is based on the mean temperature and total precipitation for each week within a Climate Division, as well as the CMI value from the previous week. The CMI responds rapidly to changing conditions, and it is weighted by location and time so that maps, which commonly display the weekly CMI across the United States, can be used to compare moisture conditions at different locations. Description: A Palmer derivative, the CMI reflects moisture supply in the short term across major crop- producing regions and is not intended to assess long-term droughts. Pros: identifies potential agricultural droughts Developed by: W.C. Palmer, 1968 regional_monitoring/cmi.gif Surface Water Supply Index (SWSI) The Surface Water Supply Index (SWSI) was developed by Shafer and Dezman (1982) to complement the Palmer Index for moisture conditions across the state of Colorado. The Palmer Index is basically a soil moisture algorithm calibrated for relatively homogeneous regions, but it is not designed for large topographic variations across a region and it does not account for snow 7 accumulation and subsequent runoff. Shafer and Dezman designed the SWSI to be an indicator of surface water conditions and described the index as "mountain water dependent," in which mountain snowpack is a major component. Description: The SWSI is designed to complement the Palmer in the state of Colorado, where mountain snowpack is a key element of water supply; calculated by river basin, based on snowpack, streamflow, Pros: represents water supply conditions unique to each basin Cons: changing a data collection station or water management requires that new algorithms be calculated, and the index is unique to each basin, which limits interbasin comparisons Developed by: Shafer and Dezman, 1982 Reclamation Drought Index The Reclamation Drought Index (RDI) was recently developed as a tool for defining drought severity and duration, and for predicting the onset and end of periods of drought. The impetus to devise the RDI came from the Reclamation States Drought Assistance Act of 1988, which allows states to seek assistance from the Bureau of Reclamation to mitigate the effects of drought. Description: like the SWSI, the RDI is calculated at the river basin level, incorporating temperature as well as precipitation, snowpack, streamflow and reservoir levels as input Who uses it: the Bureau of Reclamation, the State of Oklahoma as part of their drought plan Pros: by including a temperature component, it also accounts for evaporation Cons: because the index is unique to each river basin, interbasin comparisons are limited Developed by: the Bureau of Reclamation, as a trigger to release drought emergency relief funds Deciles Arranging monthly precipitation data into deciles is another drought-monitoring technique. It was developed by Gibbs and Maher (1967) to avoid some of the weaknesses within the "percent of normal" approach. The technique they developed divided the distribution of occurrences over a long-term precipitation record into tenths of the distribution. They called each of these categories a "decile." The first decile is the rainfall amount not exceeded by the lowest 10% of the precipitation occurrences. The second decile is the precipitation amount not exceeded by the 9 Description: groups monthly precipitation occurrences into deciles, so by definition, "much lower than normal" weather can't occur more often than 20 percent of the time Who uses it: Australians Pros: provides an accurate statistical measurement of precipitation Cons: accurate calculations require a long climatic data record Developed by: Gibbs and Maher, 1967 lowest 20% of occurrences. These deciles continue until the rainfall amount identified by the tenth decile is the largest precipitation amount within the long-term record. By definition, the fifth decile is the median, and it is the precipitation amount not exceeded by 50% of the occurrences over the period of record. The deciles are grouped into five classifications.

Předpověď sucha Během události ENSO (El Niño–Southern Oscillation) mohou nastat sucha téměř všude na světě, vědci nalezli nejsilnější spojení mezi ENSO a suchem v Austrálii, Indii, Indonésii, Brazílii, v části jižní a východní Afriky, oblastmi v Pacifiku, střední Amerikou a různými částmi USA. ENSO události zdá se mají silný vliv na oblasti v nižších zem. šířkách, obzvláště v rovníkovém Pacifiku a okolních tropických územích. Intenzita anomálií v mírném pásmu není tolik souvislá s ENSO jako v nižších zem. šířkách. Nyní se měří na spousta místech v Pacifiku teplota, proudy a vítr a na základě těchto dat se vytváří počítačové simulace. Vědci v současné době nejsou schopni na většině míst předpovědět sucha na měsíc a více dopředu. Predikce sucha je závislá na srážkách a teplotě. ENSO and Drought Around the World During an ENSO event, drought can occur virtually anywhere in the world, though researchers have found the strongest connections between ENSO and intense drought in Australia, India, Indonesia, the Philippines, Brazil, parts of east and south Africa, the western Pacific basin islands (including Hawaii), Central America, and various parts of the United States. Drought occurs in each of the above regions at different times (seasons) during an event and in varying degrees of magnitude. Ropelewski and Halpert also looked at the link between ENSO events and regional precipitation patterns around the globe (1987). Northeastern South America from Brazil up to Venezuela shows one of the strongest relationships. In 17 ENSO events, this region had 16 dry episodes. It is not uncommon to find the rain forests burning during these dry periods. Other areas from their study also showed a strong tendency to be dry during ENSO events. In the Pacific basin, Indonesia, Fiji, Micronesia, and Hawaii are usually prone to drought during an event. Virtually all of Australia is subjected to abnormally dry conditions during ENSO events, but the eastern half has been especially prone to extreme drought. This is usually followed by bush fires and a decimation of crops. India has also been subjected to drought through a suppression of the summer monsoon season that seems to coincide with ENSO events in many cases. Eastern and southern Africa also showed a strong correlation between ENSO events and a lack of rainfall that brings on drought in the Horn region and areas south of there. Another region they found to be abnormally dry during warm events was Central America and the Caribbean Islands. Thus, ENSO events seem to have a stronger influence on regions in the lower latitudes, especially in the equatorial Pacific and bordering tropical areas. The relationships in the mid-latitudes aren’t as pronounced nor are they as consistent in the way wet or dry weather patterns are influenced by El Niño. The intensity of the anomalies in these regions is also more inconsistent than those of the lower latitudes. NOAA’s Climate Prediction Center has short papers on the typical impacts associated with ENSO and La Niña episodes. Can We Predict ENSO? If we can understand some of the teleconnections discussed above, it can lead us to some general predictive capabilities via numeric computer models that can help us determine and conclude when conditions are favorable for the onset of an event. Numeric models try to emulate processes (and dynamic relationships) that occur in nature using sets of numbers and equations. But once an event is underway, forecasting its duration and intensity are difficult at best. Scientists don’t know how to predict drought a month or more in advance for most locations. Predicting drought depends on the ability to forecast two fundamental meteorological surface parameters, precipitation and temperature.

Dopady sucha Dělíme na přímé a nepřímé, ekonomické, environmentální a sociální. Přímé – snížená produktivita půdy, zvýšení rizika požárů, snížení vodní hladiny, zvýšená úmrtnost zvířat atd. Nepřímé jsou následky přímých – snížený příjem zemědělců, zvýšení ceny dřeva a jídla, nezaměstnanost, zvýšená kriminalita, migrace lidí atd. Ekonomické – z hlediska peněz -úhyn zeměděl. zvířat, ryb, rostlin, zvýšení cen energie, jídla, snížení výnosů z turistiky a rekreace atd. Environmentální – z hlediska degradace krajiny - zvýšení rizika požárů, degradace půdy, nedostatek pitné vody, migrace a úhyn zvěře. Sociální – dopad na lidi – zhoršení zdraví lidí, zvýšení konfliktů, snížená kvalita života, vzrůst chudoby, migrace lidí. In fact, the U.S. Federal Emergency Management Agency has estimated that drought costs the United States an average of $6-8 billion dollars every year, making it the costliest natural disaster. Losses from the 2002 drought may be as much as $20-30 billion. When drought occurs, it can have many far-reaching impacts. That's because water is an important part of so many of our activities. We need water for everything from human, wildlife, and plant health; to washing dishes, river rafting, and fishing; to growing food, cooling engines, and producing electricity. When we don't have enough water for these activities, there will most often be a negative impact. But drought does not always affect everyone negatively. Well drillers, for example, may be more in demand, and construction companies may have fewer rainy days to slow down their building progress. To prepare for drought, people need to figure out how drought will affect their own particular interests or activities. Types of Drought Impacts Drought impacts are often grouped as economic, environmental, and social. When we talk of economic impacts, we mean those impacts of drought that cost people (or businesses) money. For example: Farmers may lose money if a drought destroys their crops or stunts the crops' growth, causing lower yields and poor crop quality. If a farmer's water supply is too low, the farmer may have to spend more money on irrigation or to find new water sources, like wells. Ranchers may lose livestock, or they might have to spend more money on feed and water for their animals. People who work in the timber industry may be affected when trees, especially young trees, die or wildfires destroy stands of timber. Businesses that manufacture and sell recreational equipment, like boats and fishing equipment, may not be able to sell some of their goods because drought has dried up lakes and other water sources. Businesses that depend on agricultural production, like tractor manufacturers and companies that process food, may lose business when drought damages crops or livestock. Power companies that normally rely on hydroelectric power (electricity that's created from the energy of running water) may have to spend more money on other fuel sources if drought dries up too much of the water supply. The power companies' customers would also have to pay more. Water companies may have to spend money on new or additional water supplies. Barges and ships may have difficulty navigating streams, rivers, and canals because of low water levels, which would also affect businesses that depend on water transportation for receiving or sending goods and materials. People may have to pay more for food. Drought also causes environmental losses because of forest fires; soil erosion; damage to plants, animals, and their habitat; and air and water quality decline. Sometimes the damage is only temporary, and conditions return to normal when the drought is over. But sometimes drought's impact on the environment can last a long time, or may even become permanent if, for example, an endangered species was lost because of low stream flows. Examples of environmental impacts include: Losses or destruction of fish and wildlife habitat Lack of food and drinking water for wild animals Increase in disease in wild animals, because of reduced food and water supplies Migration of wild animals, leading to a loss of wildlife in some (drought-stricken) areas and too many wildlife in areas not affected by drought Increased stress on endangered species Lower water levels in reservoirs, lakes, and ponds Loss of wetlands More fires Wind and water erosion of soils, reduced soil quality Social impacts of drought include public safety, health, conflicts that arise between people when there isn't enough water to go around, and changes in lifestyle. Many of the impacts that we consider economic and environmental also have social impacts. Examples of social impacts include: Mental and physical stress on people (for example, people may experience anxiety or depression about economic losses caused by drought) Health problems related to low water flows (for example, low water supplies and water pressure make fire fighting more difficult) Loss of human life (from heat stress and suicides, for example) Threat to public safety from an increased number of forest and range fires Reduced incomes Population migrations (from rural to urban areas) Fewer recreational activities

Dopady sucha na kontinenty FEMA has estimated that drought costs the United States $6–8 billion annually (FEMA, 1995). Federal Emergency Management Agency

Dopady sucha top ten

Porovnání výskytu sucha s ostatními katastrofami

lake Mead Arizona

Montana 2002

Colorado 2002 This is what remains of Barr Lake along I-76 northeast of Denver. The wooden dock is stranded well away from the water.

Země s nedostatkem obnovitelných zdrojů vody Spotřeba vody na člověka v ČR za den cca 130l.

Prevence Šetřit s vodou – nevylévat zbytečně vodu, když ji lze použít ještě někde jinde (k zalití květin, nebo mytí). Zkontrolovat jestli nám někde nekape voda. Místo mytí se ve vaně se sprchovat, nesprchovat se zbytečně dlouho, používat úspornou hlavu s malým průtokem vody. Úsporné splachování záchodu. Nezalívat zbytečně často trávník. Xeriscaping – rostliny odolné vůči suchu. DROUGHT SAFETY TIPS To conserve water indoors and outdoors: Never pour water down the drain when there may be another use for it such as watering a plant or garden, or for cleaning. Verify that your home is leak free. Take shorter showers. Replace your showerhead with an ultra-low-flow version. Don't let water run while shaving or washing your face. Brush your teeth first while waiting for water to get hot, then wash or shave after filling the basin. Don't overwater your lawn. As a general rule, water every five to seven days in the summer and every 10 to 14 days in the winter. Plant it smart. Use Xeriscape landscaping. For more information on Xeriscape landscaping contact your water management district. Water lawns during the early morning hours when temperatures and wind speed are the lowest. This reduces losses from evaporation. Promote water conservation in community newsletters, on bulletin boards and by example. Encourage your friends, neighbors and co-workers to "do their part." Don't assume - even if you get your water from a private well - that you need not observe good water use rules. Every drop counts. Facts on water use in and around our homes Canadians use an average of 335 litres of water each day for household and gardening purposes. The United States uses around 380 litres; Israel uses 135 litres. Only 10% of our home water supply is used in the kitchen for drinking, cooking and washing dishes. About 65% of indoor home use occurs in the bathrooms. Toilets use 40% more water than needed. The greatest water use occurs in the summer when about half to three quarters of treated water is sprayed on lawns.

Seznam zdrojů informací Internetové stránky http://www.drought.unl.edu/ http://www.em-dat.net/ http://www.reliefweb.int/ http://www.populationaction.org/