Over the past 34 years, rainfall in
Uganda has decreased by about 12 percent even though many of the global climate
models predict an increase in rainfall for the area, according to an
international team of researchers. Rainfall levels in Uganda impact agriculture,
food security, wildlife habitats and regional economics as well as the
prevalence of certain diseases.
"We didn't plan to study the
climate," said Steven J. Schiff, Brush Chair Professor of Engineering in
the Departments of Neurosurgery, Engineering Science and Mechanics and Physics,
Penn State. "But we realized we needed the information to study
infections. The biggest need for infant brain surgery in the developing world
is infection-caused hydrocephalus."
While there are congenital cases of
hydrocephalus, infectious disease causes the majority of cases in Uganda.
Infections are the cause of large numbers of infant deaths during the first
four weeks of life and half those deaths take place in sub-Saharan Africa.
Those who do not die, often develop hydrocephalus, a buildup of fluids in the
brain cavities that can cause head deformation and cognitive deficits. It is
estimated that there are 100,000 to 200,000 such cases each year in sub-Saharan
Africa.
"Previous research showed that
intermediate levels of rainfall are associated with peaks in the number of
cases of hydrocephalus," said Schiff. "We had to take a careful look
at rainfall. We had county-level information, but we had to get down to the
village level."
Paddy Ssentongo, assistant research professor,
Center for Neural Engineering and Engineering Science and Mechanics, Penn
State, worked with several government agencies in Uganda to establish a
collaboration. Using census data, election data and village boundary
information, combined with weather and climate data from the African desk of
the U.S. National Oceanic and Atmospheric Administration, they managed to fuse
village details with satellite rainfall data over the past 34 years. They
reported their results in a recent issue of Scientific Reports.
"Uganda is a developing country
dependent on rain-fed agriculture," said Ssentongo. "If it depends on
agriculture then you look at rainfall. If rainfall isn't dependable, farmers
lose crops."
Another consideration, according to Ssentongo, is that understanding the fluctuations in rainfall can help municipalities and national governments plan infrastructure to improve growth and the economy. Resilience needs to be built into agricultural planning to adjust to the decrease in rainfall in the greater Horn of Africa over these past four decades. In addition, the Bwindi Impenetrable National Park in Southwest Uganda is also affected by the drier climate and the Bwindi Forest is the last habitat of the mountain gorilla.
For these reasons, the Ugandan
government was very interested in fully understanding the climate data and supplied
detailed geospatial data so they could have location-specific climate data for
planning.
The researchers found that the
rainfall predicted for East Africa on a decadal scale by models using the
effects of the El Niño Southern Oscillation and the Indian Ocean Dipole did not
account for as much of the rainfall fluctuations as expected for the past 34
years. This is in part because the rainfall fluctuations fall during shorter
timespans than decades.
Uganda has two rainy seasons, one
from March to May and one from October to December. The rainy seasons have
higher malaria rates, but are also related to a variety of bacterial and viral
infections that have seasonal and rainfall related rates. Hydrocephalus also
has a pattern related to the rainfall seasons which varies by location.
"With climate data at this
level, we can pinpoint the address of every baby with hydrocephalus and
correlate that to a square on the satellite rainfall maps,"
said Schiff. "We can know how much rain had been falling on that address
when the infant became ill."
The researchers' goals are to
identify vulnerable areas for epidemic diseases, particularly neonatal sepsis
and through this identification develop ways to prevent and treat these
diseases.
"We can't track the disease
causes unless we take the major environmental conditions into account,"
said Schiff.
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