Translate
Resources
The Wilderness Project - Middle Cuando Expedition Report
| Author: | Various TWP |
| Language: | |
| Topic: | Water and River Basins |
| Type: | Research |
| Last updated: | 14 April 2026 |
This document provides an overview of the Wilderness Project's 2024 expedition to Lake Kariba, focusing on environmental monitoring, water quality, biodiversity, and conservation efforts.
Lake Kariba and The Wilderness Project Overview
The Wilderness Project conducted a 19-day scientific expedition along Lake Kariba to assess its ecological health, water quality, biodiversity, and human impacts, providing vital baseline data for sustainable management.
Lake Kariba's Geographical and Hydrological Significance
Lake Kariba is the world's largest man-made reservoir, located on the Zambezi River between Zambia and Zimbabwe, covering approximately 5,580 km².
The expedition covered 834 km along the Zimbabwean side from the Zambezi River mouth to the Kariba dam wall.
The lake supports fisheries, hydroelectric power, and tourism.
Since its construction in 1959, it has been relatively well-studied but requires ongoing monitoring for sustainable management.
Located 1,800 km upstream of the Indian Ocean, it is critical for regional water, food, and power security.
Fixed Survey Sites and Data Collection Methods
Systematic monitoring was established at 123 fixed sites for long-term ecological assessment.
Data collected included aerial drone surveys, water quality tests, eDNA samples, macroinvertebrate assessments, pathogen samples, bat-call recordings, and island and tributary surveys.
Fixed sites enable comparison over time to detect ecological and water quality changes.
Drone flights and systematic sampling occur every 10 km along the lake shore and tributaries; eDNA and macroinvertebrates are sampled every 50-75 km.
Water Quality Findings and Concerns
Water quality generally aligns with WHO guidelines but shows localized exceedances.
pH and nitrate levels exceeded WHO standards at several points; water treatment recommended for communities.
The Deka tributary shows potential pollution with pH dropping to 3.6 and elevated dissolved ions, likely from upstream mining.
Effluent pipes from crocodile farms show high dissolved ions, posing ecosystem and health risks.
Water parameters stay consistent above 10 m depth; deeper waters show increased nutrients due to a stable thermocline.
Climate change has decreased the epilimnion depth from 20 m to 10 m, affecting nutrient distribution and aquatic life.
Human Activities and Fishing Industry Impact
People are present along most of the lake, mainly engaged in fishing, with activity concentrated near towns like Binga, Chibuyu, Chalala, and Kariba.
The Zimbabwean side has 5.10 buildings per km²; the Zambian side has 10.82 buildings per km².
Fishing, especially Kapenta (small pelagic fish), is the primary livelihood; 342 Kapenta boats observed.
Kapenta catch declined from 20,000 tonnes in 1990 to about 6,000 tonnes in 2020 due to overfishing, climate change, and reduced lake levels.
3,963 artisanal fishers using gillnets were observed; illegal fishing camps and boats are present.
ZimParks patrols actively combat illegal fishing, but increased support is recommended.
Recommendations for Sustainable Lake Management
Key suggestions include ongoing water quality monitoring, habitat conservation, fisheries assessment, and invasive species control.
Continue water quality testing at fixed sites, especially Deka tributary and aquaculture effluent pipes.
Include depth measurements to monitor thermocline changes affecting nutrients.
Protect wetland habitats to preserve biodiversity, especially bird species.
Reassess fisheries sustainability and fishing practices.
Promote overexploitation of red claw crayfish as an alternative protein source to reduce pressure on native fish populations.
