What you need to know:
- Decline. Although several parts of the country are currently experiencing floods due to the downpour, analysis by weather agencies show a drop in the rainfall received in Uganda for the past years, writes Paul Tajuba.
Francis Hategyeka, the chairperson Kanara Sub-county in Kamwenge District, recalls vividly how his area used to receive heavy rainfall in the 1970s.
The rains, Hategyeka says, would come in time, as early as February, to be specific. Today, his area, like many other parts of Uganda, has to wait for rains until mid-March.
“We used to receive a lot of rainfall for many months but we now have more dry months than it was in the 1970s,” Hategyeka told this paper at the end of February.
And for Milika Katenda, a peasant farmer based in Buteke village in Luweero District, rainfall has become so unpredictable that February is no longer the planting season it was decades ago.
“We are no longer sure of when the wet season is begins or ends. You just plant and pray that there is enough rainfall until crops mature,” the 67-year old Katenda says.
Coincidentally, an analysis by Crane Analytics, a digital analytics firm specialising in research, business intelligence and analytics, data visualisation and management services based in Kampala, agrees with Hategyeka’s assertions.
According to analysis of the country’s average annual rainfall for the past 16 years, Uganda has lost 20 millimetres of rainfall.
According to Wikipedia, one millimetre of rainfall is the equivalent of one litre of water per square meter. It is measured by a rain gauge. Uganda’s total surface area is 241,038 square kilometres, which translates to 241,038,000 square metres. Going by this, we have lost annually 4.8 billion litres of water that used to pour from the skies!
The UN Food and Agriculture Organisation estimates that beans needs at least 300 – 500mm of water to mature, cotton 700 – 1300, groundnut 500 – 700, and maize 500 – 800, Sorghum/millet 450 – 650mm.
The analysis shows a gradual shift in rainfall from 750 – 2000mm per year to 1,000 – 1639mm per year.
“There is a noticeable variation in average annual rainfall across the weather stations located in different districts of the country,” Mr Augustine Wandera, the head of Crane Analytics, says.
The period of analysis spans 16 years, from 2001 to 2016 for which the data used to arrive at the conclusions was extracted from the Statistical Abstracts published annually by the Uganda Bureau of Statistics (UBOS).
Data from weather stations across the country such as Entebbe, Kampala, Kasese, Lira, Masindi, Mbarara, Soroti and Tororo, support the analysis.
According to analysis, Entebbe weather station recorded 1,539.4mm of rainfall between 2001 – 2008 but saw a drop 1,529.2mm in 2009 – 2016. At Kampala weather station, 1,418mm of rainfall was recorded in 2001 – 2008 but again dropped to 1,255.6mm seven years later.
Lira registered 1,486.6mm in 2001 – 2008 but 1,454.2mm in 2009 – 2016.
The same drop was registered at Tororo station with 1,582.2mm in 2001 – 2008 and 1,459.5mm seven years later.
To arrive at the data, Mr Wandera said they sliced the data in two equal sub-periods; 2001 – 2008 and 2009-2016, which permitted them to perform different forms of comparisons across the two sub-periods.
They then undertook a month on month comparison using bar graphs to visually display the monthly shift in the rainfall pattern across each weather station.
They then visually compared average annual rainfall between the two sub-periods using slope graphs and finally fitted a linear time trend on the annual rainfall to determine the annual changes for each weather station.
The Uganda National Meteorological Authority (UNMA) manages weather information and issues weather forecast every late February and September. The weather forecast is, however, not 100 per cent is.
The said 20mm drop, according to Mr Godfrey Mujuni, a data manager at UNMA, is a small drop since Uganda has registered more drops and gained rainfall in different seasons and years.
“What should worry Ugandans is the frequency. Some months which used to have 20 rain days now have 18 days or less,” Mr Mujuni says. This, he adds, impacts on crop productivity since crops will not receive rainfall to take them through maturity.
Mr Mujuni says some regions of the country, especially Karamoja, have gained some rainfall over the past decades with some parts of Karamoja registering 30mm up from 20mm registered many years ago.
According to rainfall trend analysis done by UNMA over 30 years (1981 – 2010) for Lango sub-region, the March – May season has “a significance decline”, while the September – November (Second rainfall season), has increased in volume.
“Comparing the current ten years (2008-2017) with the long term periods (1981-2010) during March-May, it can be observed that over Lango sub-region, the current 10 years received less rainfall than the past long term periods. This is another evidence that the first rainfall season is on a decline over the sub-region,” an analysis done by the weather agency says.
During March to May season over Lira, the rainfall had been normally distributed within the district until around 1984 when abrupt changes occurred with a decline in the amount of rainfall until around 2014 when a slight increase was observed.
The same UNMA analysis indicates that there was a decline between 1961 and 1965 then steady increase up to around 1984 and thereafter average rainfall received over the district with no observed abrupt change over the entire periods.
Causes of rainfall decline
Scientists correlate the decline in rainfall to destruction of the environment. In a past interview, Environment State minister Gorreti Kitutu said 40 per cent of rainfall received in Uganda is influenced by natural features such as wetlands and forests. The other 60 per cent rainfall is influenced by external features such as the Indian Ocean.
But Uganda’s natural features are under attack from encroachers, who have turned them into farms, settlements, industries and search for fuel wood. More than 90 per cent of Ugandans depend on fuel wood for cooking, something that has resulted into the depletion of the country’s forest cover.
Forests, according to the global conservation organisation; World Wide Fund for Nature, “besides providing habitats for animals and livelihoods for humans, forests also offer watershed protection, prevent soil erosion and mitigate climate change.” Forests also influence rainfall formation.
However, between 1990 and 2005, natural forest estate outside protected areas reduced by 35 per cent (from 3.46 million hectares in 1990 to 2.3 million hectares in 2005).
A 2017 Joint Water and Environment Sector Review Report now estimates the country’s forest cover at 9 per cent.
Wetland cover is also reducing with the latest estimates by ministry of Water and Environment, putting it at less than 10 per cent.
Degradation of wetlands, which among other things stores water before it joins major streams, rivers or lakes, threatens the country’s plans of rolling out irrigation, as water availability will be a challenge for some areas that do not have big lakes and rivers.
According to official statistics, Uganda has irrigation potential of 3.03 million hectares. Out of that, the current coverage in irrigation is 0.5 per cent. The total land under irrigation is around 15,000 hectares countrywide. Uganda has the lowest percentage in East Africa in terms of utilising its irrigation potential. Tanzania is at 3.6 per cent, Kenya is at 2 per cent and Burundi at 1.6 per cent.
Environmental degradation has resulted into climate change, also referred to as global warming, which has seen increase in average surface temperatures.
Other factors that have led to climate change include increased levels of atmospheric carbon dioxide produced by burning fossil fuels, industrial and automobile gases.
Ms Agnes Kirabo, the executive director of Food Rights Alliance, a civil society organisation, says the variations in rainfall, more so a decline, should worry everyone owing to Uganda’s dependence on nature to produce food. Little rainfall will mean reduced crop productivity which will negatively affect food security, materials for agro-based industries and incomes of farmers and dealers.
“People tend to look at agriculture as a sector for only farmers but it is not. How many people can afford to buy imported food if we fail to prove ours? How many will this affect? So there is really reason to worry,” Ms Kirabo says.