By ISAIAH ESIPISU
Mention of the word El Niño sends shivers to several communities in Africa who live in lowland areas. However, these extreme rainfall phenomena are exactly what Dodoma desperately needs to sustain lives of the speedy growing population in Tanzania’s capital city.
A team of local and international scientists from Sokoine University of Agriculture (SUA) and University College London (UCL) in collaboration with the Ministry of Water and Irrigation including the WamiRuvu Basin Water Board have been studying the Makutapora well-field (the only source of water for Dodoma city) to understand how the groundwater responds to different climatic conditions and human consumption.
“Based on the results, the government will be in a position to make informed decisions on whether to keep abstracting water only from Makutapora or find supplementary sources of water to meet the ever growing demand,” Lister Kongola, retired government hydrologist
“Through our research, we are seeking to understand groundwater resources in Makutapora, the renewability, the sustainability and critically how people use this precious resource,” said Richard Taylor, a professor of hydrogeology at the UCL and the Principal Investigator for a project known as GroFutures.
And after a few years of intensive research, the scientists have discovered that the well-field found in an area mainly characterised by usually seasonal rivers, vegetation such as acacia shrubs, cactus trees, baobab among others that thrive in dryland areas can only be recharged during extreme floods that often destroy agricultural crops and even property.
Dodoma became Tanzania’s capital city in 1974, though the administrative offices remained in Dar Es Salaam. Given a fact that the entire Dodoma region is semi-arid with an average annual rainfall of 550 mm, the current population of about 500,000 residents entirely rely on groundwater from the Makutapora well-field, from which they pump out 61 million litres of water every day, according to government records.
However, since 2016 when President John Pombe Magufuli issued an executive order to relocate all government ministries and institutions as well as diplomatic offices from Dar Es Salaam to Dodoma, the city has become a beehive of activities as people and authorities rush to put in place the right infrastructure to accommodate the expected rise in population.
As a result, the demand for water is expected to rise amid the changing climatic conditions, putting much more pressure on the Makutapora well-field.
“Makutapora is quite a special site, given that it is the longest known groundwater level record in Sub Saharan Africa,” said Prof Taylor. “A study of the well-field over the past 60 years reveals that recharge sustaining the daily pumping of water for use in Dodoma city occurs episodically and depends on heavy seasonal rainfall associated with El Niño Southern Oscillation,” said the professor.
So far, according to the loggers (data registering equipments) installed in several monitoring wells within the Makurapora basin, the water level has been declining since 2016 when the positive recharge was recorded following the 2015-16 El Niño rains. The scientists attribute the decline to heavy abstraction of the water for domestic use, but also, the researchers are in the process of finding out if tough climatic conditions, changes and variations could be another factor.
“In the end of the year 2015, we installed river stage gauges to record the amount of water in the streams. Through this, we can monitor an hourly resolution of the river flow and how the water flow is linked to groundwater recharge,” said Dr David Seddon, a research scientist from UCL.
According to Lister Kongola, a retired hydrologist who worked for the government from 1977 to 2012, the demand for water in Dodoma has been rising over the years, from 20 million litres in the 1970s, to 30 million in the 80s and to the current 61 million litres per day at the moment.
“With most government offices now relocating from Dar Es Salaam to Dodoma, the establishment of the University of Dodoma and other institutions of higher learning, health institutions, and emergence of several hotels in the city, the demand is likely going to double in the coming few years.
Already, President Magufuli has issued 62 land title deeds for construction of diplomatic missions and five others to accredited global organisations to facilitate the shift from Dar Es Salaam to Dodoma.
“The ongoing study is a stitch in time,” said Kongola. “Based on the results, the government will be in a position to make informed decisions on whether to keep abstracting water only from Makutapora or find supplementary sources of water to meet the ever growing demand,” he said.
One of the alternative options would be to construct dams and also explore alternative sites with reliable aquifers. The other option is to pump water all the way from Lake Victoria which is over 600 kilometres away from Dodoma.
The good news, however, is that seasons with El Niño kind of rainfall are predictable. “By anticipating these events, we can actually amplify them through some very minimal but strategic engineering intervention that might allow us to actually increase the amount of water replenishment in the well-field,” said Prof Taylor.
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