Where does water come from in East Africa?

So far this blog has discussed how access to water in East Africa is valued, in terms of money, health, and labor, and also how access to water can create serious human-wildlife conflicts. Another incredibly important topic that needs addressing is the science of water in East Africa.  Where does water come from?  What causes drought in the region? Answering these questions is critical in understanding access to water in East Africa.

Photos of Mt. Kilimanjaro just 6 years apart.
Photo courtesy of http://researchnews.osu.edu/archive/scndkili.htm

Where does the water come from?  Where do people get their water?  The water utilized by both rural and urban populations in East Africa comes from a variety of sources, including lakes, rivers, springs, and boreholes.  Water in East Africa even comes from glaciers like those on Mt. Kilimanjaro.  Dr. Lonnie Thompson of Ohio State University studies Mt. Kilimanjaro and has warned that sometime between 2015 and 2020 the famous ice fields will melt (which is due to climate change and this will be explored further in a future blog post).  Dr. Thompson predicts that the impact of this on local water supplies will be serious.  The population living near the base of the mountain relies on the melt water flowing from the glaciers and ice fields, as well as the rainforests that cover the sides of the mountain, to supply their springs with water.  If the ice on Mt. Kilimanjaro disappears completely the springs could dry up and East Africans depending on that water may be forced to look somewhere else to meet their daily water needs. 

In fact, communities near Mt. Kilimanjaro are already feeling these effects.  The town of Moshi, which is just south of Mt. Kilimanjaro in Tanzania, depends on the Shiri Spring and Nsere Spring for 95% of their water.  However, the glacial changes on the mountain have seriously affected the supply of water to residents in the Moshi Municipality.  This has forced the management of the Moshi Urban Water and Sewage Authority to ration their precious water.

Map of the groundwater resources mapped by researchers
from the British Geological Survey and the University College London.
Photo courtesy of Environmental Research Letters

Water in East Africa also comes from boreholes that tap into ground water resources.  This is an important water source for people because boreholes and wells can be dug where there is an absence of lakes, rivers, and streams.  Researchers from the British Geological Survey and the University College London mapped the ground water resources and aquifers and found that the notoriously dry continent of Africa is actually sitting on a vast reservoir of ground water. According to this research, countries that were previously deemed as water scarce may have substantial groundwater resources. These findings could impact East Africans and potentially improve water access with the drilling of more boreholes.  However, the researchers recommend that boreholes should be appropriately located for small-scale water supply because this would be more appropriate than developing high-yielding boreholes without properly understanding the local groundwater conditions.  

What causes droughts in the region?  These variations in precipitation are exceedingly important because they influence access to water.  Droughts also influence where and how much water is available. Droughts can dry up wells and lakes that local populations depend on.  A study published in Science  predicted that the recent droughts in East Africa result from cooler waters on the other side of the globe.  La Nina conditions in the tropical Pacific Ocean impact rain in East Africa and have been found to reduce the amount of rain in the area.  This same study study found that East Africa’s rains have been influenced by the warming and cooling of the Pacific Ocean for the past 20,000 years, based on data collected from sediments on the bottom of Lake Challe, which is a crater lake in the foothill of Mt. Kilimanjaro.

Understanding where water resources come from and what influences rain in East Africa is critical to understanding access to water. Droughts can dry up springs, lakes, and rivers.  Greater knowledge about groundwater stores can help improve access to water through the digging of boreholes.  Access to water is critical for those living in East Africa, and the science of water can influence people's access to water. 

Women pumping water from a borehole
Photo courtesy of http://www.ucis.pitt.edu/africa/studyabroad
/Pitt_In_AfricaUniversityofPittsburgh.php

Women collecting water from a river.
Photo courtesy of http://www.guardian.co.uk/