Lake Malawi outflows through main outlet Shire River nourishes the entire Zambezi River basin as they sustain 90 percent hydro power locally, support downstream irrigation for sugarcane production including nurturing biodiversity in a wetland recognised globally the Elephant Marsh, a new scientific study scientific study suggest.
However, there are growing fears that recent lake level decline raises concerns over future climate change impacts, including risks if the Lake’s outflow threshold is passed.
This will likely have economic consequences to millions of people who benefit from this shared resource.
Researchers under the Uncertainty Reduction in Models for Understanding Development Application (UMFUULA) project used Water Evaluation and Planning (WEAP) a software tool for integrated water
resources planning developed by the Stockholm Environment Institute.
WEAP is easily accessible and is used in analysis of water demand (water use patterns and allocation) and supply (streamflow, groundwater, reservoirs and transfers).
Once established, WEAP can be used as a decision support tool for assessing water availability and supply requirements for key sectors.
Scenarios can also be explored to evaluate the implications of different water development and management options on water availability and demand.
This can help to customize the modelling and analysis to the local context of hydrology and management decisions is crucial to generating stakeholder relevant information.
They then used this model to run scenarios of future water availability, under state-of-the-art projections of potential future climate change using scientific data and stakeholder engagement. The study was conducted between April 2016 and June 2018.
Ajay Bhave lead author tells iHubOnline sustainability of future investments will require more effective and extensive data collection and use.
Lake Malawi and Shire Basin Development Plan need to address uncertainty in future water availability and demand changes, including how multi-year shifts in lake levels would affect water trade-offs between hydropower, irrigation and the environment, explains Ajay, a research fellow at the School of Earth and Environment, University of Leeds.
The study published in the Journal of Hydrology on (12th February) show a wide range of impacts due to large differences in climate model projections in Lake Malawi.
According to Ajay two key issues emerged from the findings. These are catchment of the Lake Malawi is spread across three countries namely; Malawi, Mozambique and Tanzania. Statistics in terms of inflows shows 41% of all water that enters the lake originate from Tanzania.
This means that if water demand in the Tanzania part of the catchment increases this could reduce amount of inflows into Lake Malawi, posing risks to water availability in the Zambezi basin.
“Climate change impacts on rainfall in the catchment area is uncertain, and could lead to a substantial decrease or increase in water flowing into the lake. If water flowing into the lake decreases, there is a potential for Lake level to fall below the outflow threshold,” he said.
He added that under such a scenario, hydropower generation and irrigation would be adversely affected, while water available for Elephant Marsh ecosystem will reduce.
“If water flowing into the lake increases, there is a potential for Lake Malawi levels to rise to such levels that would cause flooding along the shores including areas where Shire river passes through. Such an event had occurred from 1979 to 1980, causing much damage then,” Ajay elaborated the findings in an
Cosmo Ngongondo, Associate Professor of Geography and Earth Sciences at University of Malawi, Chancellor College acknowledged the study as the most comprehensive on the water balance of Lake Malawi.
Despite some data limitations Ngongondo noted, researchers have tried their best to source both observed and remotely sensed data for the model
“There are various dimensions and interests on the Lake. The researchers carefully avoided “prescribing” a particular dominant scenario in terms of the future Lake Malawi levels based on the different models. The model results therefore, need synthesis,” Ngongondo suggested when asked to comment on the findings.
David Mkwambisi, Associate Professor of Environment and Development at the Malawi University of Science and Technology who was part of the research team warned that climate and potential changes in water
demand in neighbouring Tanzania poses risks to infrastructure development that is crucial for long-term socio-economic development.
“Policy makers need to be aware of the uncertainty in future rainfall changes due to climate change and understand the risks from potential dry or wet conditions. There is a need to develop policies that can
help transboundary water management collectively,” Mkwambisi advised while referring to the shared Lake.