Africa

Towards protecting the water towers in the Lake Kivu and Rusizi River basins, Rwanda

By Providence Akayezu, Ken Mwathe and Felicien Karekezi Uwizeye

A number of rivers take source from these mountains of the North Western Rwanda

 

Climate Resilient Altitudinal Gradients - CRAGs

The altitudinal gradients in the Kivu-Rusizi have attracted the ongoing CRAG work; to first understand these landscapes, their ecosystem values, and their exposure to climate change impacts predicted and already happening. The CRAG approach was launched in 2012 during the development of the African Great Lakes Conservation Strategy; and in April 2014 the tool started being tested through initiatives to promote climate change resilience in the CRAG region. These landscapes can be defined as watersheds that start in the mountains and end in the lakes. The Kivu-Rusizi basins were selected to test the CRAG tool because they qualify in terms of topography, ecosystem services and elevation ranges. Generally, the minimum elevation of 1,000 m a.b.s.l, house some priority Key Biodiversity Areas and support fishing, control erosion, provide freshwater for irrigation, domestic use and hydropower production.

View of landscapes in the Sebeya River Catchment in the North Western Rwanda, one of the targeted sites for piloting the CRAG initiatives

 

In the Kivu-Rusizi watersheds, the current climate resilience activities comprise of conducting a study on sediment fingerprinting, to identify the potential sources of erosion in the catchments. This involves the collection of sediment and soil data at different locations, considering hydrological patterns and geological units in the catchments. The fieldwork also engages local community who are beforehand introduced to the project and mobilised for active participation. The field data go through analyses; including laboratory to trace metals and modelling to produce the erosion hotspot maps. These activities are currently being implemented in Sebeya, Ruhwa and Muhira River systems. Sebeya River empties into Lake Kivu after being enriched with its tributary rivers that cross a range of landscapes, while Ruhwa and Muhira Rivers discharge their water in Lake Tanganyika via Rusizi River. The results from sediment fingerprinting are complemented by climate change vulnerability assessments and both steps feed into the on-the ground interventions for local communities’ resilience and adaptation.

Ruhwa River at the boundary between Rwanda and Burundi (right side is Rwanda, left side Burundi). The river crosses Nyungwe and Kibira National Park, before empting into Rusizi River that connects to Lake Tanganyika

 

Sediment fingerprinting, a scientific technique to identify the sources of erosion and river sedimentation

The three selected rivers experience heavy sediment load that is mainly caused by erosion happening in the upstream of river catchments. The sedimentation level becomes much severe when the cultivated land in the upstream are not protected against erosion and unsustainable mining being practiced along the river banks.  BirdLife Rwanda and the BirdLife partner in Burundi – ABN, have conducted the soil and sediment data collection, engaging communities and at the end the erosion hotspot maps were produced. To get sediment data, water was collected at 4-5 m from the confluence of the main river and its tributary, the water was then filtered and sediments trapped on filter membranes (Nylon polyamide, pore size= 0.45 micrometre and diameter= 47 mm). Furthermore, the soil data was obtained after digging at each selected location, and colleting a small soil amount and store in Ziploc plastic bag. The sample contamination was controlled with equipment used for sampling and storing both samples. The plastic containers were preferred over metallic ones, to avoid any metal interference with samples, which would cause wrong laboratory results.

Community engagement during water filtration process

 

In total, 129 samples were collected in Sebeya and Ruhwa Catchments of Rwanda, while 65 samples from Ruhwa and Muhira Catchments of Burundi. Along with these field data collection, a number of local communities were mobilised: 75 and 45 community members (male and females) selected from existing cooperatives in Rwanda and Burundi respectively. They were able to understand the CRAG interventions and at the same time had a chance to participate to the fieldwork activities as Site Support Groups.

On Muhira River in Burundi, representatives of local community groups also participated in the fieldwork for sediment fingerprinting

 

Prioritizing intervention areas from the erosion hotspot maps

The final output from the sediment fingerprinting study was an erosion hotspot map, produced for each targeted catchment. The map shows four categories of erosion hotspots, labelled as ‘’levels’’, and directly match with the land use, land cover’s contribution to the sediment discharge into the river. Level 1 corresponds to the sites with high, level 2 medium, level 3 low and level 0 negligible contribution to the river sedimentation. The map information was verified with field validation and level 1 and 2 were found to be of first priority for land restoration interventions; because they include landscapes with active mining, abandoned grazing lands and agriculture on non-protected steep slopes. In contrast, level 3 and 0 comprise areas with natural, planted forest, grazing and sustainable agricultural lands.

The forest and tea plantation landscapes were among the level 0 or 3: negligible or low contribution to the sediment load in the river catchment

 

Agricultural areas on steep slopes and without measures for holding the soil during the rain, were found to be in level 1 or 2

 

Planning for climate change interventions in the three targeted river systems

This step assesses the vulnerability to climate change of selected community groups; by incorporating local knowledge into the scientific findings from sediment fingerprinting. Around 32 representatives from sites identified in level 1 and 2 (high and medium contribution to river sedimentation) were invited for a three days workshop. The training allowed communities to understand resources in their respective river catchments, discover themselves and give weight to possible risks to each of the resources. It was also an opportunity to develop together timeframes and propose interventions to address severe and recurring hazard events such as erosion, flooding and landslide. These interventions require collaboration between all actors in the river catchment, including government, civil society, donors, investors and local communities. If there is continuous funding and successful stakeholder engagement, there is hope to keep tracking on the changes in the erosion rates throughout time and monitor the project's impact.

Community members were participating in the resource mapping exercise

 

Please find the full report here (PDF, 11.17 MB).

For more news about CRAGs, please visit our CRAG news page here.