Mystery in the waters
To help understand the formation of the lake, an international scientific team from Tanzania, France, Belgium and the UK started exploring and coring the bottom sediments of Lake Ngozi in October, writes Wilfred Edwin
About 15km southeast Mbeya city, in a secluded mountain valley, lies Lake Ngozi.
The lake measuring 2.5 km long and 1.6 km wide, is on the eastern section of the Mporoto Ridge Forest Reserve.
Recognised as the second largest crater lake in Africa, it is a place of mystery and magic, according to the communities that live in the surrounding area, among them the Nyakyusa, the Safwa and the Kinga.
The Nyakyusa tell of sinister monsters and poisonous gases in the lake.
They say the lake was formed by a magician named Lwembe (“razor”), who was chased out of his birth village of Ukwama in Makete district because people in his village were tired of his dirty tricks.
The man fled to Rungwe district, where he continued dabbling in magic, especially involving robbing the Nyakyusa of healthy animals. Finally, Lwembe created a magic lake into which cows disappeared whenever they grazed nearby.
The legend has it that people who went too near the lake also disappeared.
After sustaining massive losses of cattle, Nyakyusa elders decided to do something about the lake, then found a big rock, which they heated for three days over an intense fire.
They then rolled it into the lake, casting a spell as they did it; thereupon they were free of its menace.
Another legend says the lake is home to a giant serpent-like monster who comes out only on sunny days.
But the Safwa believe the lake has existed since time immemorial.
Scientific information, however, shows that Lake Ngozi was formed after a volcanic eruption more than 40,000 years ago.
Its waters have been undergoing changes in colour, depending on the prevailing atmospheric condition of the day.
To help understand the formation of the lake, an international scientific team from Tanzania, France, Belgium and the UK started exploring and coring the bottom sediment of Lake Ngozi in October.
The analysis of new cores from Lake Ngozi will help in the reconstruction of the past environment, climate and volcanic activity in the Mbeya region, improving the understanding of climate change in the tropics, a major issue for developing countries in Africa, Central America and Indonesia.
This expedition is an initiative of the new international Rungwe Environmental Science Observatory Network.
The network of scientists aims to document climate, volcanism, natural resources and human activities in the Rungwe province and Mbeya region.
One of the goals of the network is to train Tanzanian and non-Tanzanian students in fieldwork observations and measurements, in ecology, botany, hydrology, limnology, soil science and land use approaches, and to support the contribution of local communities to the project
The team decided to carry out the research in the lake because Rungwe district has more than 10 volcanic lakes, strung out in a row down to Lake Nyasa.
The researchers plan to explain the outcome of the study to the local communities and to support development initiatives in Mbeya region by offering their expertise on the long-term behaviour of natural resources in the tropics.
The study will help to improve the understanding of rift volcanoes, tropical rivers, soils and forests in developing countries.