An Assessment of the Impact of Climate Change on Water Resources of Senegal and Ghana - Review of Related Literature

Africa is already a continent under pressure from climate stresses  and is highly vulnerable to the impacts of climate change. Many  areas in Africa are recognized as having climates that are among  the most variable in the world on seasonal and decadal time scales.  Floods and droughts can occur in the same area within months  of each other. These events can lead to famine and widespread  disruption of socio-economic well-being. For example, estimates  reported at the workshop indicate that one third of African people  already live in drought- prone areas and 220 million are exposed to  drought each year. Many factors contribute and compound the impacts of current  climate variability in Africa and will have negative effects on the  continent’s ability to cope with climate change. These include poverty,  illiteracy and lack of skills, weak institutions, limited infrastructure,  lack of technology and information, low levels of primary  education and health care, poor access to resources, low management  capabilities and armed conflicts. The overexploitation of land resources  including forests, increases in population, desertification and land  degradation pose additional threats (UNDP, 2006). In the Sahara and  Sahel, dust and sandstorms have negative impacts on agriculture,  infrastructure and health. As a result of global warming, the climate in Africa is predicted to become  more variable, and extreme weather events are expected to be more frequent  and severe, with increasing risk to health and life. This includes increasing  risk of drought and flooding in new areas (Few et al. 2004, Christensen et al. 2007)  and inundation due to sea-level rise in the continent’s coastal areas  (Nicholls 2004; McMichael et al. 2006).  Africa will face increasing water scarcity and stress with a subsequent potential  increase of water conflicts as almost all of the 50 river basins in Africa are  transboundary (Ashton 2002, De Wt and in sub-Saharan Africa. Under  climate change much agricultural land will be lost, with shorter growing  seasons and lower yields. National communications report that climate  change will cause a general decline in most of the subsistence crops, e.g.  sorghum in Sudan, Ethiopia, Eritrea and Zambia; maize in Ghana; Millet  in Sudan; and groundnuts in Gambia. Of the total additional people at  risk of hunger due to climate change, although already a large proportion,  Africa may well account for the majority by the 2080s (Fischer et al. 2002).  Africa is vulnerable to a number of climate sensitive diseases including malaria,  tuberculosis and diarrhoea (Guernier et al. 2004). Under climate change,  rising temperatures are changing the geographical distribution of disease  vectors which are migrating to new areas and higher altitudes, for example,  migration of the malaria mosquito to higher altitudes will expose large  numbers of previously unexposed people to infection in the densely  populated east African highlands (Boko et al. 2007). Future climate variability  will also interact with other stresses and vulnerabilities such as HIV/AIDS (which is already reducing life expectancy in many African countries) and conflict and war (Harrus and Baneth 2005), resulting in increased susceptibility and risk to infectious diseases (e.g. cholera and diahrrhoea) and malnutrition for adults and children (WHO 2004). Impacts of climate change and variability The climate of West Africa, particularly in its Sahelian part, has been undergoing recurrent variations of significant magnitude, particularly since the early 1970’s. The region has experienced a marked decline in rainfall and hydrometric series around 1968–1972, with 1970 as a transitional year. The decline in average rainfall, before and after 1970, ranges from 15% to over 30% depending on the area.This situation resulted in a 200km southward shift in isohyets. Average discharge in the region’s major rivers underwent concomitant and highly pronounced variations compared to rainfall values. An average decline in the range of 40–60% in discharge has also been observed since the early 1970s. The recorded decline in the discharge of major watercourses has resulted in the significant reduction in surface area of the main natural wetlands. The average area of the Hadéjia Nguru floodplain (on the Komadugu Yobe river system in northern Nigeria) decreased from 2,350km2 in 1969 to less than1,000km2 in 1995. That of the Inland Delta of the Niger River decreased from 37,000km2 in the early 1950s to about 15,000km2 in 1990. The surface area of Lake Chad evaluated at 20,000km2 during the wet years before 1970, has shrunk to less than 7,000km2 since the early 1990s, leading to the splitting of the lake into two parts. Today, only the southern part contains water permanently. The proliferation of floating weeds (water lettuce, water hyacinth, Typha, etc.) results from the general disruption of the climate in the region. This is particularly due to the reduced flow velocity in watercourses, temperature change as well as the deterioration of water quality. These weeds hinder fishing, navigation, the functioning of irrigation schemes, hydroelectric developments. Furthermore, they provide favourable conditions for the multiplication of vectors of water-borne diseases, such as malaria and the outbreak of new diseases (e.g. the Rift Valley fever). They also choke several water bodies of the region, including wetlands with biological diversity of global importance. The recharge of the region’s aquifers has also noticeably decreased, often due to the decline in rainfall and surface runoffs. For instance, on the Bani sub-watershed, across the upper reaches of the Niger River   in Mali, water tables reached their lowest levels in 1997. The decline in water tables has significant consequences on the depletion coef- ficients (e.g. the Senegal River at Bakel or the Niger River at Koulikoro). The variability of the climate has not spared the coastal areas. Very sensitive to erosion, beaches and dune ridges along West Africa’s coastal area show evidence of retreat at variable paces: from 1–2m, to more than 20–30m per annum in Senegal and along the Gulf of Guinea, respectively. In Senegal, an accelerated retreat of the coastline was observed between 1987 and 1991 and resulted in the disintegration of the dune ridges. The recurrent drought, resulting from climate change and variability, accelerates desertification, which in turn contributes to the persistence of drought. This cycle is likely to play a part in increased desert encroachment. The increase in discharge observed over some sub-watersheds such as the Nakambé, can be explained by in- creased runoff coefficient due to the degradation of the vegetative cover and the soil. As an illustration of the accelerated erosion, one can cite the case of the Niger River and its tributaries along its middle course, where important transport of solids was observed in the main riverbed, which consequently tends to silt up the latter. Climate variability directly affects West African countries’ national economies in general, and those of the Sahelian States in particular. Three main reasons account for the above situation: (a) the significant contribution of rainfed agriculture to the region’s economy; (b) the poor level of water control; (c) the poor replenishment of reservoirs on which some countries sometimes depend heavily for the generation of hydropower and electricity supply to industry and households. The city of Ouagadougou, which is supplied from impoundments, experienced severe supply shortfalls in 2002 and 2003. In February 1998, Ghana was faced with a severe energy crisis as a result of the drop in water level in Lake Volta, sometimes below the required threshold for feeding the turbines of the Akosombo dam. This dam, together with the more modest one of Kpong, account for 95% of Ghanaian electricity consumption. Due to these various reasons, it is hardly surprising that at the regional level, a significant correlation exists between annual rainfall and flow conditions on the one hand, and economic growth rates on the other hand. (IUCN   2004) Impacts on weather patterns Flooding Flooding is the most prevalent disaster in North Africa, the second most common in East, South and Central Africa, and the third most common in West Africa (AWDR, 2006). In North Africa, the 2001 disastrous flood in northern Algeria resulted in about 800 deaths and economic loss of about $400 million. In Mozambique, the 2000 flood (worsened by two cyclones) caused 800 deaths, affected almost 2 million people of which about 1 million needed food, 329,000 people were displaced and agricultural production land was destroyed (AWDR, 2006). Drought Between July 2011 and mid-2012, a severe drought affected the entire East Africa region and was said to be “the worst drought in 60 years.” Impacts on Water Supply and Quality Observable effects of climate change on water resources in Africa include flooding, drought, change in distribution of rainfall, drying-up of rivers, melting of glaciers and the receding of bodies of water.  The following discussion features some of the more prominent water resource systems in west Africa and how they are being affected by climate change.  The outlook looks bleak for these water resource systems and the governments of the African countries housing these water resource systems should take immediate action and galvanize First World nations which are the major pollutants to take notice and most importantly, take action. West Africa Entire economies suffer when the water levels of Africa’s huge rivers drop. Ghana, for example, has become totally reliant on the hydro-electric output of the Akosombo dam on the river Volta. Mali is dependent on the river Niger for food, water and transport. However, great stretches of the river are now facing environmental devastation as a result of pollution. Upper Senegal Basin This study evaluated the possible effects of climate change on the water resources systems and the impact of statistical bias correction on the forecasted climate change signals in the water-based variables taken in the Upper Senegal Basin in west Africa. The input for this study came from the bias corrected and original climate data from the regional climate model REMO. The Max Planck Institute for Meteorology-Hydrology Model (MPI-HM) was used to simulate the following variables - soil moisture, runoff, evapotranspiration, and the river discharge (Mbaye, et al., 2015). The Senegal River Basin is a good example of an area where development objectives could not be sustained because of the drought-induced desertification process. The main hydrologic constraint on development is the decrease in the annual flow volumes of the river, which emphatically points out that the water resources availability of the Senegal River Basin has been substantially reduced lternative time series mechanisms are hypothesized to account for the decreased flow volumes in recent decades. Another observation is that the desertification processes and the landscape degradation seen in the area has also been ascribed to climate change effects. The government’s efforts to address the desertification has been hampered by the existence of complex socioeconomic forces and the presence of basic hydrologic constraints to the development of the Senegal river basin development (Venema, et al., 2010). Sassandra River Shared By Guinea and Cote d’Ivoire The Sassandra River is a transboundary river located in west Africa that has its spring in the forested region in Guinea and at the Denguélé region of Côte d’Ivoire. It crosses the western part of Côte d’Ivoire and moves into the city of Sassandra in the coast of the Gulf of Guinea. Its total length is 650 km with a basin area of 62,700 km2, with majority of it belonging to Cote D’Ivoire. Scientific studies have been done on the Sassadra transboundary river basin on the management and evaluation of its water resources.  The studies have shown that the water availability and runoff in the Sassandra River have increased from 10 to 13% during the past 50 years then decreased between 1971-195. Another study modeled the  climate model of spatial resolution, 2.5◦ × 3.75◦ with the A2 greenhouse gas emission scenario. Recently, Yao [22] worked on the hydrologic modeling of a tributary of the Sassandra River (the Lobo). This study was carried out using the regional climate model RegCM3 of spatial resolution of 0.44◦ × 0.44◦ under the A1B emission scenario. Yao improved a deficiency by reducing the scale of climate modeling to better appreciate local specificities (Coulibaly, et al., 2018). Lake Victoria Lake Victoria is the second largest freshwater lake in the world, surrounded by Kenya, Tanzania and Uganda.  Global climate change could cause Lake Victoria, to dry up in the next 500 years. Even more serious, is that the White Nile, one of the two main tributaries of the Nile, could lose its source waters in just a decade. University researchers have used ancient sediment from outcrops along the edge of the lake and generated   a water-budget model to see how the lake’s levels respond to changes in rainfall, evaporation, temperature, and solar energy. Their findings have indicated that a rapid lake level decline was very possible tens of thousands of years ago and could reoccur in the future. The scientists pointed out that the model they created predicts that at current rates of temperature change and previous rates of lake level fall, Lake Victoria could have no outlet to the White Nile in as little as 10 years. Every major port in Lake Victoria could be landlocked within a century, and Kenya could lose access to the lake in 400 years. The result would significantly affect the economic resources supplied by the lake and the livelihoods of approximately 40 million people living in the Lake Victoria Basin.  Kenya and Tanzania depend on the lake's freshwaters to support their fishing industries because the lake harvests more than one million tons of fish annually. Uganda would be deprived of its primary source of electricity via hydropower and the water that sustains the Nile during non-flood stages. The Kagera River basin, which is the main river that flows into Lake Victoria, feeds rainwater to Rwanda and Burundi which rely on agriculture and livestock production Lake Victoria gets most of its water from rain, and each year, the area gets about 55 inches of rainfall. The sediment analyzed from along the lake shows rainfall levels from 35,000 to 100,000 years ago were about 28 inches, or almost half of what they are today. The water-budget model in the study shows low amounts of rainfall caused the lake to dry up at least three times in the past 100,000 years and could happen again (University of Houston, 2019). Lake Chad Lake Chad used to span 10,000 kilometers, but today, it is just around 1200 sq. km. In 50 years, Lake Chad has shrunk to one-tenth of its previous size.  Scientists and lake residents have pointed out that climate change has been a huge factor in its shrinkage but have also blamed it on rising populations and the demands of the dams that were built for irrigation and hydroelectricity. The lake is important to the indigenous communities living around it in one of the world's poorest countries. The locals have been using their ancestral knowledge to overcome problems of scarce resources. The predicament of Lake Chad shows how climate change is affecting many different communities across Africa.  It has become an issue of survival, an issue of life, since hundreds of millions of people depend on it. Lake residents have clamored for solutions and have asked for urgent action for those people who are getting impacted who didn't create this climate change. Lake Chad is located in a big semi-arid region south of the Sahara desert called Sahel. Historically, the area has been sensitive to drought, and the lake’s depth has  fluctuated dramatically in size during prolonged dry periods. More than 30 million people rely on the lake’s fresh water, supporting economic activity, irrigation and fishing in the four countries the lake touches – namely Chad, Cameroon, Nigeria and Niger. With the lake’s shrinkage, the surrounding communities are struggling and there is intense competition for the dwindling resource. In some of the lakeshore communities, men have to look for work elsewhere during dry seasons when the lake can no longer sustain them. This has led to massive migration including people going to Europe to search for work. Often, it is the women and children who are left behind who have to fend for themselves in looking for food. To survive, many farmers across the lake are reviving an old technique known as zai where they dig pits to catch rainwater, then add compost and plant seeds. The technique concentrates nutrients and can boost crop yields by up to 500%.  Chad is among the poorest nations in the world with 62% of its population considered destitute, as most people rely on subsistence farming. Climate change has added to existing political and economic instability, driving further food insecurity (World Economic Forum, 2019). Mount Kilimanjaro Glaciers The gradual yet dramatic disappearance of the glaciers on Mount Kilimanjaro is a result of climate change (IPCC, 2001). The glaciers act as a water tower and several rivers are now drying up. It is estimated that 82% of the ice that capped the mountain, when it was first recorded in 1912, is now gone. (IPCC, 2001). Impacts on Agriculture and Food Across Africa the landscape is changing. Droughts, heat stress and flooding have led to a reduction in crop yields and livestock productivity. East Africa is facing the worst food crisis in the 21st century. According to Oxfam, 12 million people in Ethiopia, Kenya and Somalia are in dire need of food. Rainfall has been below average with 2010/2011 being the driest year since 1950/1951, a serious problem for a continent almost entirely dependent on rain for its agriculture. The Oyebande and Odunuga (2010) study discussed the series of droughts of the past three decades that affected the Sudano-Sahelian zone of west Africa, particularly Niger, Volta and Senegal basins impacted the water resources, ecosystems and the fragile economies of at least 13 of the 16 countries of the region. Declining rainfall, highly variable in time and space has resulted in more than proportionate decrease in river discharges, and declining level of freshwater bodies. This situation translated into falling groundwater levels and accelerated desertification process, hence major crises of food insecurity and massive migration, which often leads to conflicts. The challenges and uncertainties associated with the impacts of future climate changes on water resources in West Africa are further compounded by many other factors, including regional demographic factors, nonexistent or inadequate water policies, inefficient management strategies and lack of reliable and adequate data. Impacts on ecosystem Climate change has already led to changes in freshwater and marine ecosystems in eastern and southern Africa, and terrestrial ecosystems in southern and western Africa. The extreme weather events have demonstrated the vulnerability of some of South Africa’s ecosystems. The migration patterns, geographic range and seasonal activity of many terrestrial and marine species have shifted in response to climate change. The abundance and interaction among species has also changed (IPCC, 2014). Coastal Wetlands Wetlands can be defined as “areas of marsh, fen, peatland, or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish, or salt, including areas of marine water the depth of which at low tide does not exceed six meters” (Convention on the Wetlands, 1971, Article 1.1). This encompasses a wide range of aquatic ecosystems covering approximately six percent of the Earth’s surface (Rebelo et al., 2010), such as floodplains, swamps and marshes, peatlands, lakes, mangroves, reefs, and river deltas. In West Africa, while coastal wetlands are mainly composed of mangroves, they are sometimes backed by freshwater swamp forests such as in the Niger Delta; there are also secondary grasslands in the coastal lowlands that flood seasonally, such as in the vicinity of Accra in Ghana (Hughes & Hughes, 1992). Interest in the wetlands of tropical Africa has heightened because of their importance as hot spots for the development and maintenance of biodiversity; their vital role in providing food, water, and livelihood security to the mainly poor people living around them; and, most recently, for their ability to sequester atmospheric carbon (Adekolaa & Mitchella, 2011). Climate change could impact wetlands by changing their hydrologic and ecological environment, for instance through (Erwin, 2009; Hamilton, 2010): 1. Changes in aquatic thermal regimes (water temperature), with implications for thermal optima of plants and animals, rates of microbially mediated biogeochemical transformations, density stratification of water bodies, and dissolved oxygen depletion. 2. Changes in hydrological regimes of discharge and floodplain inundation (water flow), which determine the ecological structure and function of rivers and floodplains, and the extent and seasonality of aquatic environments. 3. Changes in freshwater-seawater gradients where rivers meet oceans, affecting the distribution of marine, brackish, and freshwater environments and the biogeochemical processing of river water reaching the coastal zone. Responses in species’ distribution from such changes are not well known, although it is known that many species in coastal wetlands respond to even small changes in water levels (Jalloh et al., 2012). Climate Change Outlook in Senegal Senegal remains vulnerable to environmental shocks including recurring natural disasters including floods and droughts, which will increase in magnitude and extent due to increased climate variability. Roughly 67 percent of Senegal’s population resides in the urban coastal zone, also the location of 90 percent of Senegalese industrial production. This coastal area is characterized by low-lying, rapidly expanding, high population suburbs, high water tables and poorly planned drainage systems. In addition to extreme events, rising sea levels place much of the coastal population, infrastructure and ecosystems at risk from flooding and erosion. Climate change has also impacted climate sensitive sectors like agriculture as 70 percent of production is rainfed.  It has also affected the fisheries and the livestock industries, which account for 20 percent of GDP and employ a majority of the workforce (Climate Links, 2017). Climate Change Outlook in Ghana Ghana’s vulnerability to climate change lies in its social and spatial differentiation. Each of the country’s ecological zone possesses unique socio-economic and physical attributes that characterize their resilience and sensitivity to the factors brought about by climate change. To lessen the impact of climate change, the measures provided have been reactionary. The responses from the government and the actions of the citizenry have not been proactive in adapting to the impacts of climate change which include high incidence of weather extremes and disasters, rising sea levels, declining rainfall variability and totals and increasing temperatures. All these are expected to have a negative impact on the country and its future. Farming is going to be affected because of the poor rainfall making the investments in agriculture less profitable, risky and expensive. Other important problems include dismal and insufficient infrastructure, restricted capacity in human resources development, a puny sub-regional network, insufficient financial resources and a small allocation in the national budget, the siltation of the river beds, flooding, excessive rainfall which causes a dangerous run-off, the poor location of settlements and farms in the country’s flood plains, inappropriate methods of farming leading to the compression of the soil which impedes infiltration, the degradation of land along the banks of the river, the lack of correct flood management structures, and the inappropriate disposal of solid waste.  All these challenges have to be addressed by the government and the private sector of Ghana as the effects of climate change (CC DARE, 2019). What future climate is to be expected? Significant uncertainties surround the science of the future climate. Most climate change scenarios predict a decline in precipitation in the range of 0.5–40% with an average of 10–20% by 2025. Many of these scenarios portray a generally more pronounced downtrend in flow regimes and the replenishment of groundwater. As a result of the major droughts and a number of recent floods with unusual magnitudes, specialists expect exacerbated extreme climate events in some parts of West Africa. Most coastal countries also considered scenarios of increase in sea level (0.5. to 1m over a century), with more or less significant losses in housing zones and economic infrastructures and the disappearance of significant areas of mangrove and coastal wetlands. However, it is important to point out that the climate change scenarios used do not consist of definite predictions but rather present plausible future climates. Considering the many possible future scenarios, what matters is the ability to manage the uncertainty. This includes reducing current vulnerability to climate variability and extreme   events as well as keeping management options open enough to deal with the worst-case scenarios and to take advantage of opportunities that may arise. Is West Africa adequately prepared to cope with this situation? West Africa has been faced with recurrent drought since the early 1970s. Many attempts have been made to respond appropriately to this situation. The most significant of them is unquestionably the creation of the Permanent Interstate Committee for Drought Control in the Sahel (CILSS). Since then, CILSS has been very active in the following fields: (a) agro-hydro-climatic data collection and management; (b) the setting up of an early warning system; (c) research and training, through its AGRHYMET Regional Centre (AGRHYMET: Regional Centre for Training and the Application of Agrometeorology and Operational Hydrology). Other initiatives include PRESAO (Seasonal Rainfall and Flow Forecast for West Africa) launched in 1998; the West and Central African component of the Global Hydrological Cycle Observing System (HYCOS-AOC) whose pilot phase is being implemented since 2000; the West and Central African component of the FRIEND Project (Flow Regimes from International Experimental and Network Data) set up since 1992; and more recently, the AIACC programme for assessing the impacts and adaptations to climate change which includes projects for West Africa. Finally, the project on Strengthening the Capacities of CILSS Member States to Adapt to Climate Change, which was launched in October 2002 at the AGRHYMET Regional Centre. Alongside these research initiatives, efforts aimed at water control were also ob- served. For instance, Burkina Faso has built more than 1,500 small water reservoirs over the past three decades and is currently experimenting with artificial rainmaking. The latter is envisaged in other countries of the sub-region (e.g. Senegal). Likewise, countries such as Niger, Benin, Mali and Senegal have also implemented the policy of constructing small water reservoirs. As mentioned previously, the region comprises only few large dams but many projects are planned. For example, there are more than 20 large dam projects that are planned on the Niger River alone (Fomi, Tossaye, Kandadji, Zunguru, Onitsha, etc…). Overall, the most noticeable responses to the recurrent drought and pronounced climate variability experienced for the past three decades in West Africa relate mainly to data collection and analysis. Indeed,   this is very important, but is far from sufficient to significantly reduce the vulnerability of the region to climate change and variability. With regard to the future climate, many countries of the region have proposed, in their national communications, structural and economic measures that should help them to strengthen their capacity to adapt to the predicted changes. Yet, the solutions proposed by the States are often technically, financially and/or politically unachievable by individual countries. Many of these adaptation measures may be relevant only at the regional level. Conclusion Right now, the effects of climate change are already being felt by people across Africa. Evidence shows that the change in temperature has affected the health, livelihoods, food productivity, water availability, and overall security of the African people. According to the Climate Change Vulnerability Index for 2015, seven of the ten countries most at risk from climate change are in Africa. Africa has seen a decrease in rainfall over large parts of the Sahel and Southern Africa, and an increase in parts of Central Africa. Over the past 25 years, the number of weather-related disasters, such as floods and droughts, has doubled, resulting in Africa having a higher mortality rate from droughts than any other region. Therefore, additional studies need to be carried out in order to get more knowledge on the impacts of climate change in West Africa and other parts of the world, also recommended by Mamadou Lamine and others, 2015, especially as surface andground waters are usually used for human consumption.