HYDRO-METEOROLOGICAL RISKS IN UGANDA

1. HYDRO-METEOROLOGICAL RISKS IN UGANDA By Aloysius Kagoro Department of Meteorology

2. INTRODUCTION Over 70% of natural disasters in Uganda are related to extreme hydro-meteorological events such as strong winds, severe thunderstorms, droughts and floods among others; Extreme hydro-meteorological events such as droughts and floods adversely affect the entire economy a country; The poor are the most affected by these events;

3. INTRODUCTION Cont�d The risk faced from extreme hydro-meteorological events depends on the degree of, and/or the intensity of the event, which can be determined from regular monitoring and analysis

4. SOME EXTREME HYDRO-METEOROLOGICAL EVENTS Extreme hydro-meteorological events that pose potential risk include: Droughts Floods Landslides Hailstorms Thunderstorms Lightning

5. 1. DROUGHTS Drought has many definitions but three are most common: Meteorological Drought: This is a situation arising from deficiency of precipitation from that is expected over an extended period of time; Hydrological Drought This is a deficiency in surface and subsurface water supplies; Agricultural Drought: Deficiency in soil moisture ( a critical factor in defining crop production) It should be noted that any form of drought originates from deficiency of rainfall.

6. MBARARA1999 DROUGHT

7. SOROTI 1999/2000 DROUGHT

8. CHARACTERISTICS OF DROUGHT Unlike many other natural disasters such as cyclones, floods and earthquakes, drought has some unique characteristics in that it does not destroy food storage, shelter or infrastructure. Yet its impacts are higher in many developing countries, especially in Africa. It installs itself slowly and it is often difficult to detect its onset until some major impacts such as lack of water and food, starts to be noticed Its effects are cumulative.

9. IMPACTS OF DROUGHT Some of drought impacts in Uganda include: In Uganda where rain-fed agriculture and hydro-electric power form major sources of food and energy, drought has severe effects on the welfare of communities, especially the poor. Shortages in rural and urban water- supply Lack of adequate power, water and raw materials lead to the closure of some industries, dismissal of workers, reduction in exports; and loss in foreign earnings.

10. IMPACTS OF DROUGHT Cont�d Crops failure which leads to food shortages and famine Livestock deaths High incidence of forest and bush fires Wildlife deaths thus affecting ecotourism and the associated revenue

11. IMPACTS OF DROUGHT Cont�d People and animals are forced to migrate in search of scarce water and food. This provokes conflict s between humans and animals over limited water resources and pasture. Some of the recent droughts in Uganda include: 1983/84, 1993/94, 1999/2000, 2004/2005

12. AREAS MOST UNDER THREAT A dry stretch of land extending from Rakai in (in the south) through Sembabule, Luwero and Soroti to Karamoja in the north east. This is what is commonly known as the �Cattle Corridor�

13. AREAS MOST UNDER DROUGHT THREAT

14. IMPACTS OF EL NINO AND LA NINA ON THE CLIMATE OF UGANDA Anomalies in the sea surface temperature (SST) over eastern and central equatorial Pacific Ocean trigger weather and climate anomalies in many parts of the world, especially within the tropics where Uganda is found. The La Nina phenomenon is characterised by cold ocean temperature in the eastern and central equatorial Pacific Ocean, while El Nino phenomenon is characterised by warm SSTs in the same ocean basin

15. EL NINO AND LA NINA Cont�d There are high relationships between La Nina events and below normal or poorly distributed rainfall over many parts of Uganda during October to December and March to May Rainfall over eastern Africa including Uganda is enhanced (with incidents of floods and landslides) during October- December season in an EL Nino year

16. EL NINO AND LA NINA Cont�d The clear relationships between rainfall over East Africa and SSTs in the equatorial eastern and central Pacific makes SSTs valuable forecasting tools for the Uganda Department of Meteorology

17. 2. FLOODS Floods result from prolonged, high intensity rainfall. Violent thundershowers which are of short duration produce flash floods Flash floods are common in areas which experience heavy thunderstorms e.g. those areas around Lake Victoria

18. FLOODS Cont�d Made worse by : anthropogenic changes in the catchment's areas in the form of urbanisation; Various land-use changes like elimination of natural flood retention capacities (concrete and asphalt surfaces) Interference with natural drainage conditions (e.g. Nakivubo channel)

19. AREAS MOST UNDER THREAT Flat, low lying e.g. Kasese, Soroti Urban areas like Kampala and suburbs

20. 1997/98 EL NINO RAINS

21. 3. Landslides Caused by: Prolonged heavy rainfall Topography (mountainous areas) Population pressure leading to settlements on sloping grounds Poor land use and management practices

22. AREAS MOST UNDER THREAT Places in the Mt. Elgon area (Kapchorwa, Bukwe, Sironko, Manafa, Mbale) Places in the Western Uganda Mts. Of Rwenzori and Muhavura ( Kisoro, Kabale, Kasese, Bundibugyo etc)

23. THUNDERSTORMS, HAILSTORMS AND STRONG WIDS Thunderstorms, hailstorms and strong winds are associated with towering thunder clouds; Due to land-lake breeze effect, Lake Victoria and surrounding areas are among the places in the world with the highest average annual frequency of thunderstorms (Bukoba reports 226 days per year, Kampala 222 days, Entebbe 211days and Kisumu 2o2 days).

24. THUNDERSTORMS Cont�d Thunderstorm �related weather has many risks to aviation safety, Thunderstorms are a big hazard to all aircraft underneath cumulonimbus (thunder clouds) clouds. It is always accompanied by thunder and lightning, Strong down draughts (microbursts) severe gusts and turbulence, squalls, heavy rain and sometimes hail. Microbursts are extremely hazardous for aircrafts which are taking off or landing.

25. THUNDERSTORMS Cont�d In addition, Marine operations on the lake such as transport, fishing and tourism also face a risk Recall the calamity that befell MV Victoria, which capsized in Lake Victoria killing more than 800 people in May 1995 This and other accidents could possibly be avoided if meteorological information was used for safety of navigation.