AMOS BRANDEIS - ARCHITECTURE, URBAN & REGIONAL PLANNING LTD.
LAKE BAM - TWINNING PROJECT BETWEEN ALEXANDER RIVER RESTORATION ADMINISTRATON AND BURKINA FASO, AFRICAInitiated by the International River Foundation, Australia
Lake Bam, a natural lake in Burkina Faso, almost dries out during the dry season and floods the nearby town and fields during the wet season.
It suffers from the impact of sedimentation, desertification, over-grazing, possible climate change, local human activity and enhanced use of its water by the fast-growing population.
Lake Bam is 115 km north of Ouagadougou, Burkina Faso’s capital, in Western Africa. The lake is part of the Nakamb? (Volta) river system, which flows through the Central Plateau of Burkina Faso (dry southern-Sahel climate). The catchment’s area is about 2,600 km2. The mean annual rainfall is about 600 mm during the wet season (3-4 months). The dry season is very hot (40°C on average), and the annual evaporation is about 1,500 mm during the dry season.
The length of the lake varies according to season between 3-20 km, and the width varies between 0-4 km. The lake is 1.5-3.5 m deep during the wet season and only 0-1 m deep during the dry season; in extreme droughts it may dry out.
In recent years, large parts of the lake have dried out during the dry season and cut the lake into several separate lakes. The volume of the water in the lake varies between 20-34 million m3 during the wet season (up to 60 million m3 during floods) to 0-9 million m3 at the end of the dry season. Between 15-20 m3 of water evaporates during the dry season, while another 5-10 million m3 is used directly from the lake for flood irrigation and other human uses. Less than 25% of the total volume remains in the lake at the end of the dry season.
The local population, about 60,000 people, lives in mud houses in a town (Kongoussi) and in 40 small villages around the lake. The largest source of income in the region is irrigated agriculture (mainly crops), while another important source is fishing from the lake.
The lake is in the process of deterioration. Natural processes – sedimentation, high evaporation and extreme droughts – have caused environmental changes. The constantly growing population, together with global impacts from human activity, have caused over-exploitation of the area’s natural resources. Enhanced sedimentation is caused by agricultural activity around the lake and erosion of the fields, deforestation, over-grazing, an attempt to build a dirt dam through the lake, and more. Further effects of climate change could cause further deterioration. There is also severe lack of management and inadequate monitoring.
To restore the lake as the source of life for the environment and the community, many ambitious long-term steps have to be taken in order to: secure long-term water supply to a large and fast-growing population which relies totally on the water from the lake; improve the quality of the water and community health; secure a healthy and sustainable ecosystem; supply physical conditions which will secure a reasonable socio-economic status in order to avoid migration from the area; secure sustainable management of resources by the local population; deal with impacts of desertification and possible climate change in an extremely hot climate;
The main goal of this feasibility study is to analyse the problems of the lake, to define restoration options, to recommend long-term, comprehensive, sustainable and reasonable solutions and to analyse the feasibility and risks of the recommendations.
The feasibility study was prepared as a twinning project between the Alexander River Restoration Administration (ARRA), winners of the 2003 International Thiess Riverprize, Australia, and the Ministry of Agriculture, Water Resources and Fisheries in Burkina Faso. It was initiated and financed by the International Riverfoundation (IRF), based in Australia. The IRF promotes as a catalyst global collaborations of river restoration twinning projects. The International Water Centre, Australia (IWC) undertook the peer review of this study.
A comprehensive and inter-disciplinary approach was developed, based on analysis of other relevant projects in Africa. The study suggests a large variety of actions and projects on the catchment and lake level. Many of them were already tried successfully in other projects. These include three main sets of recommendations: further data collection/production, physical projects and management recommendations. The unique feature of this study is the modular approach, which enables its implementation at different levels simultaneously, according to available budget or other considerations. The implementation of many of these recommendations simultaneously and in a combined but modular manner, on different scales and locations, is intended to achieve a synergetic effect which will lead to an improvement of the situation of the lake and its surroundings. The recommendations combine the local expectations and needs to implement immediate physical actions, with long-term actions, and with many recommendations regarding the involvement and the capacity-building of the local population. The recommendations towards gaining the trust and support of the local stakeholders seem to be crucial to achieving sustainable and successful solutions.
The recommendations on the catchment level are aimed to stop in the long term the deterioration of the basin. The main physical recommendations include the construction of sediment traps, terraces and stone dykes, and a large-scale afforestation project. The main management recommendations are to avoid the construction of further dams upstream, to prevent initiated bush fires and to define nature reserves. In addition, the preparation of a catchment model and a landuse and vegetation survey is recommended. The recommendations on the catchment level have not been financially estimated, as they should be further discussed with international donor and aid agencies, as these are far beyond the scope of this study.
The recommendations on the lake’s level include physical projects, such as raising the level of the dam (lake’s outlet) by 50 cm (to add about 40% of the lake's volume); construction of a water control system for the lake’s outlet; construction of terraces on the lake’s margins for flood protection of built-up and agricultural areas (up to 1.3 m high); raising the level of the fields (behind the terraces) to avoid flooding (up to 500 hectares); excavation of sediments from the lake in the shape of “internal reservoirs” (5-8m deep) which will, on the one hand, add volume to the lake and create deeper water reservoirs within the floodplain near the fields (less evaporation and less pumping needed), and on the other hand will supply the soil needed for raising the fields; creation of a buffer along defined banks of the lake; construction of sediment traps on the tributaries; an irrigation pilot project, habitat for fish in the lake; afforestation; fencing; and construction of hydrological measurement stations on the tributaries. The study also includes many management recommendations on the lake’s level, such as: the establishment of the “Lake Bam Restoration Administration”; signing a treaty and setting regulations; workshops with the local people; water management of the lake for agricultural use; landuse planning and building restrictions for floodplain protection; management of the buffer zone; herbicides and pesticides management; zoning of grazing and livestock management; protection of trees; fishing management and stocking of the lake; ongoing monitoring; and sewage management.
Cost estimations were prepared for all proposed actions and projects on the lake’s level. The estimated cost of the overall long-term implementation of all the components is about $44 million. The cost of Stage A, which will lead to a significant change, is estimated at a total cost of $11.7 million.
The benefits, feasibility and risks of the proposed recommendations were thoroughly discussed regarding social, engineering, physical, environmental, ecological, economic and other aspects. This was done mainly by analysing other relevant projects in Africa and by discussing the main issues with the ministry, the local team members and local stakeholders. The main conclusions are: this comprehensive study is feasible; it has a relatively high probability of materialising; the goals should be met; a significant change can be achieved already in the short term (Stage A – between 3-5 years); the modular approach which does not “put all the eggs in one basket” but proposes many actions to achieve together a synergetic effect reduces risks; the engineering works and methods fit the scale and the know-how in Burkina Faso; no revolutions are proposed and no foreign methods are introduced; the project fits local culture and mentality; the local population can gain a lot from this project not only because the lake will be restored but also as partners who will ”own” the project (and be part of the labour force which will carry it out); the recommendations have a high degree of public acceptance; the economic feasibility is positive (return of investment from the point of view of the Burkina Faso economy); the proposed “internal reservoirs” can be an important innovation of this project (dealing with the high evaporation rate in this hot climate); this project can be a very good case study for the restoration of many other lakes and reservoirs in western Africa and may serve to avoid mistakes when constructing new reservoirs.
The three main conditions for the success of this project are excellent management, international funding and real and constant public involvement. This project is a real opportunity to make a difference!