With declining dry season flow levels in the Mara River, it is important to think about the potential impacts if the river were to ever stop flowing. The Great Ruaha River in Tanzania gives us a good opportunity look into that possible future, as it stopped flowing during the dry season in 1993. We just learned about a project in the Great Ruaha that studies the potential increases in disease transfer across humans, livestock and wildlife that are likely to occur when limited water sources shrink in size. Here's an excerpt of an article about the HALI project in the Great Ruaha River, Tanzania...
"To understand how the next disease like SARS or bird flu could arise, take a trip to the Great Ruaha River. It meanders for 300 miles through south-central Tanzania, flowing year-round from the vast Ihefu wetlands through the Ruaha National Park.
Or it used to. Starting in 1993, the river stopped running during the dry season. Some years, it's been silent for more than 100 days.
The river offers water to the safari-famous Ruaha landscape — a grassland twice the size of Vermont that's home to lions, giraffes, endangered wild dogs, and some 30,000 elephants. The river also has been a liquid life-force for groups of semi-nomadic farmers, including the Maasai, Barabaig, and Sukuma who live on the borders of the park — and have relied on the river for themselves and their prized herds of cattle.
With no water in the river for several months, people and animals have a hard time finding a drink. "This has created more overlap between livestock, wildlife, and people as they all go for the same dwindling water resources," says the University of Vermont's Jon Erickson.
Cattle, African buffalo, and farmers all drinking from the same pool and living in close proximity, creates a perfect opportunity for what scientists call zoonotic pathogens: diseases that can jump from animals to people, like rift valley fever and bovine tuberculosis.
Erickson, an associate professor in the Rubenstein School of Environment and Natural Resources, and his Rwandan graduate student, Michel Masozera, have been studying this problem in Tanzania since 2006.
They're leading one part of the HALI Project4— a Swahili word for "state of health" and an acronym that stands for Health for Animals and Livelihood Improvement. It's a collaborative U.S.-Tanzania research effort directed by Jonna Mazet at the University of California-Davis, funded largely by the U.S. Agency for International Development. HALI includes veterinarians, water biologists, and other researchers in California as well as at Tanzania's Sokoine University of Agriculture and the Wildlife Conservation Society. Erickson and Masozera are leading HALI's socioeconomic research through UVM's Gund Institute for Ecological Economics."