The Causes and Effects of DroughtLO: To understand the causes of anti-cyclonicweather and the global distribution of droughts.Starter Activity:Write down all theways in which weuse water every day.Which ones couldyou not do without?Which ones areeasier to cut downon?
What is a drought?• Look at the pictures and come up with adefinition of your own.
A lack or of for an unusuallyperiod of , involving less than theusual over 3 monthsA lack or shortage of water for an unusually long period oftime, involving 50% less than the usual rainfall over 3 monthsA good definition for drought
A drought isA reduction in precipitation over an extendedperiod of time. (lack of rainfall)
‘Effective precipitation’The difference between actual precipitation andevapo-transpiration.
What’s different about a droughtcompared to a hurricane, earthquakeor volcano?(apart from the obvious!)
050100150200250300350400450500Jan Feb Mar Apr May June July Aug Sept Oct Nov DecRainfallorevapotranspirationinmmMonthsRainfall in Southern SpainEvapotranspirationRainfall Q: Explain which months Spain is at riskof severe drought.
Where do the droughts occur?Arid Semi Aridhttp://drought.mssl.ucl.ac.uk/drought.html?map=%2Fwww%2Fdrought%2Fweb_pages%2Fdrought.map&program=%2Fcgi-bin%2Fmapserv&root=%2Fwww%2Fdrought2%2F&map_web_imagepath=%2Ftmp%2F&map_web_imageurl=%2Ftmp%2F&map_web_template=%2Fdrought.html
Some areas are more at risk than others...Arid + High Density = High Risk
Use the atlas to gather population density data and then write adescription of the distribution of droughts globally considering thepotential risk to the areas below. (Arid + High Density = High Risk)Arid Semi AridNorth AmericaSouth AmericaAfricaAsiaOceania
How might these factors affect theseverity of a drought?
Mix and match• Complete the sheet to show all the differentfactors that affect the severity of drought.• Extension question: how might the effects ofdrought be different in an LEDC and an MEDC?