The Role of Wetlands

Wetlands are estimated to cover 131 million hectares of Africa and play a vital role for those living on and around them, particularly in terms of food production in the forms of arable and pastoral farming as well as fishing (Adams, 1992). These floodplains are found across Africa and take many forms including floodplains such as those of the river Niger and lacustrine systems like Lake Chad (Adams, 1992). However infrastructure developments such as dams and climate change are posing a threat to these wetlands and thus to the ways of life and economies that surround them (Mumba and Thompson, 2005; Adams, 1995).

Major Wetlands in Africa. Source

Many traditional agriculture methods in wetland regions make the most of all stages of the annual hydrological cycle. This means farming on the 'rising' and 'falling' flood. Farmers may plant crops such as rise as the rains arrive and then harvest these once the water has receded (Adams, 1992). After the flood recedes crops are then planted on floodplains to utilise the water that has been retained in the form of soil moisture, thus maximising the growing season and therefore crop yield (Adams, 1992). On top of this areas of wetland are used for grazing of cattle and sheep by pastoral farmers due to their abundance of vegetation(Kabii, 2004). Just as agriculture in these regions is often linked to seasonal variations so is fishing, fishermen tend to target fish as they move from the rivers and lakes into the floodplain to breed and then again as they return (Adams, 1992).

A fisherman in the Sahelian Wetlands. Source

Thus it is clear that wetlands play an important role in food production and the economies of the communities surrounding them. However this food and economic security could be threatened by unsustainable development projects. Wetlands productive nature and economic potential means they are likely to play a key role in helping areas and nations develop, however this exploitation may (and in many cases already has) cause far more damage than it does good (Adams, 1992).

A particularly damaging practice for seasonal wetlands is the damming of rivers usually for irrigation schemes or hydroelectric power. Dams are often operated as to reduce the variability of river discharge throughout the year, this removes the high flows in the wet season that lead to flooding (Adams, 1985). An example of such a dam and its related negative impacts is the Bakolori dam on the Sokoto river in northern Nigeria, the floodplain and its associated agriculture downstream of this dam supported 50,000 people (Adams, 1985). Here reduced flooding (in some areas flooding area reduced by as much as 60%) caused by the rivers damming led to a reduction in flood extent and forced farmers to switch from growing relatively high value rice during the wet season to crops such as millet, this also reduced their diversity of crops as millet was already being produced in the uplands relying on rainfed irrigation(Adams, 1985). Reduced flooding also led to a reduced range of crops which could be grown in the dry season due to lower soil moisture (Adams, 1985). Thus overall the dam seems to have had the effect of reducing both the volume of crops that can be produced and the variety, limiting food security by forcing greater reliance on fewer species which may be vulnerable to climatic changes or pests. The area saw a decrease in wet and dry season fishing due to fewer pools being found in the dry season and less flooded area in the wet season (Adams, 1985). 

The Bakalori dam. Source

These types of changes are sadly not limited to the Bakalori dam and associated floodplain but can be seen across Africa. Dieudonne Mouafo's research on the Logone floodplain in Cameroon shows similar trends. Here a dam was constructed to allow for widescale rice irrigation and again the downstream fishing industry was devastated and arable farming was effected (Mouafo et al, 2002). However there was also a great impact on pastoralists, particularly cattle herders that was not mentioned in the Sokoto study. Degradation of grazing lands due to reduced flooding caused major issues for cattle herders, many lost larger proportions of their herd or were forced to trespass in the nearby nature reserve to find suitable grazing (Mouafo et al, 2002). This led to a situation where conflict over grazing land and cattle rustling was common, thus leading to many migrating away either to protect their livelihood or simply to avoid the state of famine in the area (Mouafo et al, 2002).

However there is a somewhat optimistic end to this example. Due to the work of NGOs including the WWF and the UICN a project was launched to aid the socio-ecomic and ecological rehabilitation of the area. This is being done by re-flooding downstream keep enough water behind the dam for the rice irrigation scheme (Mouafo et al, 2002). Preliminary results showed that this was successful and the indigenous vegetation was beginning to spread again and fish were being found in the reopened waterways (Mouafo et al, 2002). However I am dubious whether such small scale re-flooding while the overall project is still focused on maintaining the rice scheme will ever lead to a situation where the floodplain can support the number of people or the economy it did pre-dam. 

There is clearly nuance involved in situations like these and it would be wrong to vilify the good intentions of governments or other institutions carrying out hydro-projects aimed at increasing food or power security. However as often seems to be the case a more bottom-up approach may be needed to minimise the risks of such projects and allow for a more win-win outcome. By involving local stakeholders projects can be planned to minimise damage to local agriculture, for example by including schemes such as that mentioned in the last paragraph throughout a project rather than in an attempt to solve a 'mistake'.