I found something new in my research that I didn't consider so have adding it in as an extra option.
The African Mythology
African mythology of the local Tonga tribe of the Zambezi Valley states that Nyaminyami the River God who lives in Lake Kariba is believed to be a serpent-like creature. He is said to be about three metres wide, but nobody dares to guess at his length.
Legends has it that the water stains red when he swims past. Chief Sampakaruma saw him on two occasions many years ago, but the river god has been in hiding since the white men arrived in the country.
According to African mythology he lived under a large rock close to the present day Kariba dam wall. No tribesman would venture near it those few who did were sucked down with their canoes in the whirlpools and never seen again. They called the rock Kariwa, the "trap" and hence the name of the lake, Kariba.
The rising water of lake Kariba covered the rock Kariwa and it now lies 30 metres below the surface annoying Nyaminyami. The tonga people also believe that Nyaminyami is married and that the building of Kariba Dam wall would seperate him from his wife, this would anger him greatly and the river god threatened the peace of the valley.
Revenge of the River God
City dwellers had mocked the stories of Nyaminyami, the river god but by 1958 the laughter had turned to chilled apprehension. Especially for those working on the project of building Kariba dam wall. Survey work on the proposed dam wall began in the late 1940's. On the night of the 15th February 1950 a cyclone from the Indian Ocean swept up the valley. Such a thing had never been heard of in this landlocked, stable land. Fifteen inches of rain, driven by a hurricane, fell in a few hours.
The river rose seven metres that night. A number of villages were swept away. When rescue teams finally managed to reach the area three days later, the putrefying bodies of antelope and other animals were seen hanging from the tops of trees. The survey team had perished in a landslide.
Work on the dam began in earnest in 1955 – but on Christmas Eve that year, an unprecedented flood stormed down the gorge and washed away the foundations of the coffer dam and the recently constructed pontoon bridge. The flood peaked, receded, and then peaked again. This had never happened before and people started to talk about the river god.
Nyami nyami struck a third time in November 1956. The heavy rains fell a month before they were due. Sudden flash floods impeded work on the dam.
The Zambezi swollen with water from local catchment areas would rise over a metre in a night. They were unaware that 1300 kilometres away the Zambezi was mobilising its forces. It is fed by a catchment area of over a million square kilometres, of which nearly half is above the lake.
Heavy rains were falling throughout this vast region. The water was being hoarded in the floodplains of Zambia and the forests of Angola, and in January the Sanyati River, which entered the Zambezi very near the new wall, suddenly came down like cavalry charge. The river rose almost six metres in the next 24 hours and surged over the coffer dam.
The largest digger truck, which had not been moved, disappeared instantly. Only in March, after much damage had been done and the project set back some months, did the river begin to subside. Such a flood should occur on average once every 1000 years.
Believe it or not in January 1958 a flood such as could be expected to occur only once in every 10 000 years, swept down the riverbed, wreaking havoc on all in its path. 16 million litres per second exploded over the suspension bridge, which buckled and heaved.
- Obviously influence from African Tribal design
- Influence through Nature - Water - like serpent
- Something thought not existed but causes terror due to devouring, or taking away
- Giant boss - like creature
- maybe the creature could be good at first offer wisdom, etc but natives lash out
- Could have command over all water elements
- Could strengthen tribes who believe in it and they could be it's soldiers/ followers that guard and protect
- Could be guarding an extremely powerful artifact e.g crystal
- Could be seeking revenge for what has happened in the past e.g natives declared war on it's peace or taking resources from it