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Le développement du lac Tchad / Development of Lake Chad

 | 
Jacques Lemoalle
, 
Géraud Magrin

II. Policy Options

2. Forecasting: Main Variables

Texte intégral

1The future of the Lake depends on several variables that, though they will be considered separately for the purposes of the analysis, do interact in reality. The main variables are water inflow, demography, and socio-economic development.

Water inflows into the Lake

2The amount of water that Lake Chad receives mainly depends on changes in rainfall and climate in the basin. These changes, which determine the state of natural resources in the region, indirectly influence the human pressure exerted on the Lake. The more the basin is affected by drought, the more the pressure on the Lake increases, through migrations of populations who have lost their herds or their ability to harvest rainfed crops. An increase in withdrawals for irrigation in the upstream part of the basin, which is probable given expected demographic growth regardless of climate scenarios, will have a greater impact in the event of a dry period at the basin scale. Conversely, an additional water inflow of 3.4 km3/year by interbasin transfer is also a possibility (CIMA International, 2011).

3Although variability is one of the main characteristics of the climate of the basin and the Lake (see I-1), it would appear that past periods make it possible to identify 10-to 20-year sequences: a wet period of around 20 years (1950-1970) was followed by a dominant Dry Little Chad state of around 15 years (1973-1989), before another Little Chad phase that could be called ordinary which lasted more than 15 years (1989-2013).

4Let us recall that the climate models currently at our disposal do not enable us to predict how water inflow and the balance of the Lake will be affected by global warming (see I-3). Global warming is, however, a certainty: it may translate into a rise in evaporation (with an inflow that remains constant) and therefore a decrease in the Lake’s surface area. It is also possible, however, that the surface area of the Lake will increase as a result of a substantial increase in inflows.

5Anthropogenic withdrawals will have an impact on inflows, but their magnitude will depend on the choices that are made. Across the Lake Chad basin, domestic and urban water consumption—currently estimated at 0.5 km3 per year for 47 million inhabitants, mostly taken from groundwater resources—will increase more rapidly than that of the population due to urbanisation, rising living standards, and industrial development. As a result of demographic growth, this consumption could reach 1.4 km3 in 2025 and 2.68 km3 in 2050 if per-capita consumption doubles. With growth of 5% per year, livestock watering could reach 1.4 km3/year in 2050.

6Irrigation is expected to continue to be responsible for the majority of the demand on the surface waters of the basin and the Lake. It is likely to enter into direct competition with the needs of the Lake by reducing its inflows. Several scenarios may be imagined in order to gain an understanding of its impacts, depending on whether the climate continues to be similar to current conditions, or if it changes to become drier or wetter. Consideration also needs to be given to the hypothesis of increasing water inflow by around 3.4 km3/year through inter-basin transfer. Conversely, the possibility of greater exploitation of groundwater for supplemental irrigation should be considered. Hence, the inflows to the Lake depend on the interplay of climate changes and anthropogenic factors (withdrawals and transfer), at the Lake itself and in the basin.

Demography

7This is the variable for which there is the least uncertainty, at the scale of the entire basin or of the LCBC countries. This is because the active population of 2030 has already been born and demographic structures evolve slowly. The populations of 2025 and 2050 will not be significantly different from today’s projections (the limitations of available censuses mean that it is only possible to calculate in terms of orders of magnitude), with imprecision increasing as the projections move farther into the future. Beyond 2050, it becomes difficult to have a clear image because of uncertainty regarding the pace of demographic transition, which could lead to different trajectories among the riparian countries.

8Uncertainty exists, however, as to the rate of population growth around the Lake itself. If the economy and the environmental context remain relatively prosperous, as has been the case since the transition to Little Chad in 1973, the migratory balance should remain positive and add to the natural growth, thereby providing very rapid population growth. Should the Lake’s agro-halieutic-pastoral systems enter into crisis—as a result of land saturation, amplification of conflicts, sudden changes in the Lake’s water level, a relative decrease in agricultural prices, etc.—and no longer appear as attractive compared to the surrounding rural or urban areas, the Lake’s population growth could come to be based solely on the natural balance, or even, if the crisis reaches a certain level, follow the trend of most Sahelian rural regions in having a negative migratory balance.

Table 4. Lake population projections for 2025 and 2050 (millions). In bold: the current situation and trends.

Table 4. Lake population projections for 2025 and 2050 (millions). In bold: the current situation and trends.
  • 3 Little information is available about the conventional basin’s demography (see II-2). Here we have (...)

Source: national censuses
Note33

Table 5. Growth scenarios for towns around Lake Chad (millions). In bold: current trends.

Table 5. Growth scenarios for towns around Lake Chad (millions). In bold: current trends.

Source: national censuses.

9Meanwhile, the population of the Lake and its extensive hinterland (within a radius of 300 km from the Chad-Cameroon-Nigeria tri-border area, see II-2) is set to increase from around 13 million inhabitants at present to 35 million in 2050. In the Lake Chad conventional basin the population is set to increase from 47 to 129 million inhabitants.

10Urbanisation dynamics should also be taken into account. Depending on the choices made and the direction taken by the economies, urban growth could be rapid or slow, and could be concentrated in the major cities (N’Djamena, Maiduguri) or in the network of secondary towns around the Lake. An accentuation of the rentier model would be favourable to the first option, whereas successful economic diversification and the search for a more balanced territorial model would favour the second option.

11The growth of these two large towns raises the issue of the relationship between urbanisation, demography, and economic development, which represents the core of Africa’s future. If, as is likely, the context of contemporary globalisation is not conducive to the creation of a large enough number of modern industrial or service sector jobs in African megalopolises for the waves of workers entering the labour market, public policies must work to promote other development models, by investing in regional development as the interface between secondary towns and their rural hinterlands (Losch et al., 2013).

Socio-economic development

12The development trajectories of the riparian states, and that of the Chad basin with its pivotal role in Africa, may have significant consequences for Lake Chad. One can thus imagine negative scenarios (a battle for resources in rural areas against a background of exploding urban poverty), positive scenarios (dynamic economies driven by the use of extractive industry rents and aid to make investments that help diversify the economy and develop the growth and employment potential of urban-rural relationships), or a continuation of the status quo (a vulnerable rural economy dependent on the natural conditions, inadequate and poorly coordinated support policies, etc.).

13In addition, these economic trajectories will be substantially dependent on political developments in the basin, which could lead to either increasing territorial fragmentation (closed borders, conflicts between countries, etc.), prolonging the current situation, or making significant progress toward regional integration.

14The LCBC could contribute to such a favourable context and benefit from it in return. It would then be asserting itself as a pivotal regional institution, indispensable to its member countries, a crucial gateway to international cooperation in terms of managing water, the environment, and regional economic development. Thanks to its ability to capitalise on available knowledge concerning environmental dynamics and how they interact with societies, the LCBC could play a central role in coordinating member country policies, in terms of water and environmental management, economic planning, and security. Funding to compensate for the effects of climate change could be contributed and used for concrete programmes benefiting local populations.

Notes

3 Little information is available about the conventional basin’s demography (see II-2). Here we have used figures from the cross-border diagnostic analysis: 37 million people in 2003 (Bdliya and Bloxom, 2012).

Table des illustrations

Titre Table 4. Lake population projections for 2025 and 2050 (millions). In bold: the current situation and trends.
Légende Source: national censusesNote33
URL http://books.openedition.org/irdeditions/docannexe/image/11689/img-1.jpg
Fichier image/jpeg, 97k
Titre Table 5. Growth scenarios for towns around Lake Chad (millions). In bold: current trends.
Légende Source: national censuses.
URL http://books.openedition.org/irdeditions/docannexe/image/11689/img-2.jpg
Fichier image/jpeg, 122k

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