…Tugwi-Mukosi, Mutirikwi dams under threat
CHIREDZI- The Zimbabwe National Water Authority (ZINWA) recently warned that Zimbabwe’s biggest inland lakes, Tugwi-Mukosi and Mutirikwi are under threat as most dams in the country have been highly affected by siltation thereby disturbing the production of sugarcane in the Lowveld.
ZINWA Regional Manager Peter Shotera said there is extreme siltation in dams in the province, excluding Tugwi-Mukosi and Mutirikwi that still have their actual holding capacity though they are also under threat.
“Tugwi-Mukosi average percentage is currently 95 and this is because it was recently constructed but this does not mean it is safe from siltation and we are afraid sugarcane farming is going to deteriorate because our water bodies are slowly being affected by siltation,” said Shotera.
Andrew Mupariwa Masvingo Provincial Mechanization Engineer also said siltation is not only affecting sugarcane farmers but all farmers in the province in general.
“Several irrigation schemes are heavily affected by siltation. Chilonga Irrigation Scheme, which gets water from Runde River failed to irrigate for years because of siltation as well as Rupangwana, ARDA Tshovani , St Joseph and Gudo Irrigation Schemes that get water from Save River,” said Mupariwa
Mupariwa also mentioned that they are working as a department on major challenges that cause siltation which include stream bank cultivation and conversation works are some of the measures.
“We are partnering some Non-Governmental Organisations (NGOs) which include World Food Programme (WFP), OXFAM, and Mwenezi Development Trust in establishing some solar powered borehole watered gardens which are plus or minus one hectare and some one and half to two hectares so that we move farmers who are practicing stream bank cultivation from riverbanks into those gardens.
“Conservation works involve contour pegging in some farms so that runoff is reduced. It is not only siltation challenge which is being faced but also the top soil which is being washed away from fields means fertile soil is lost so, we are trying to do both soil and water conservation.
“The challenge we have is not only siltation but also top soil which is being washed away from the fields and this means we are losing fertile soil and that means our yields are also going down,” said Mupariwa.
He also elaborated that veld fires are contributing to siltation by destroying trees, grass and everything that helps to bind soil together and that they are currently working together with the Environmental Management Authority (EMA) and Forestry Commission in addressing issues of afforestation through Small Irrigation Revitalizing Program (SIRP).
Currently water levels in Masvingo province are as follows: Tugwi-Mukosi 97.78%, Mutirikwi 96.41%, Bangala 20.35%, Manjirenji 89.28%, Muzhwi 99.69%, Ngezi 91.58%, Manyuchi 87.92%, Mushandike 80.63%, Bindangoma 97.78%, Tokwane 58.18%, Nyajena 87.87%, Siya 86.52%, Musaverema 80,45%, Magudu 70.81% and Chivake 96.83%.
In general terms, siltation refers to the increased concentration of suspended sediments, and to the increased accumulation of fine sediments on bottoms where they are undesirable, especially fine sand or clay is increased by soil erosion arising from agricultural practices particularly along riverbanks and deforestation.