1 Introduction

The rise in sea level throughout the world can be attributed to the warming of the world’s climate systems to about 1 °C in the last two centuries [1, 2]. The intergovernmental panel on climate change (IPCC) [1] points out that climate change will increase the risk of flooding in coastal areas around the world due to sea-level rise. Increasing sea levels will lead to the inundation of communities or settlements along the coast. Farmlands, recreational centers and buildings, and properties will be destroyed. If care is not taken, majority of the coastal people will lose their properties, lives and livelihoods [3].

The southeastern section of Ghana has two regions, namely the Volta and the Greater Accra Regions. The Volta Region section of the area has Ketu South, Keta, and Anloga as their municipalities whilst Ada East and Ada West Districts can be found in the Greater Accra Region. These districts in the southeastern section of Ghana have been battling endlessly with sea erosion. According to Kumassah [4] and Jayson-Quashigah et al. [5] some communities along the coast have seen their land eroded inland to about two kilometers. It is appropriate to refer to these communities as experiencing coastal flooding and erosion, but these floods are not temporal but can be described as a permanent activity. These activities along the southeastern coast of Ghana can be said to emanate from climate change. These activities most of the time lead to the destruction of properties while people abandoned their homes to seek refuge with families and friends in nearby towns and villages inland. The magnitude of the impacts of coastal flooding has attracted the attention of local and international research communities on the need for adaptation and mitigation [3, 6, 7]. The Ghana national climate change adaptation strategy points out that the eastern coast of Ghana is the most affected when it comes to coastal erosion with whole communities at risk of losing their houses and other infrastructure. Indeed, the flooding of the eastern coastline of Ghana has become a key developmental, research, and publicity issue [8, 9].

As a measure to curtail the threat of coastal flooding, the government of Ghana commenced the construction of a series of coastal flood defence projects along the coast. The Keta project which is the largest coastal flood defence project in Ghana was started in 2000 and was completed in 2004 [10]. This project involved stabilization of the shoreline with breakwaters and groynes, construction of a flood control structure, land reclamation from the sea, re-establishment of a road to link Anloga, Keta, and Aflao, and construction of resettlement housing units [6, 10]. The Ghana government’s attempt to build coastal flood defence walls to curb the seasonal sea inundation of the coast can be said to be the strategy of mitigation and adaptation to sea level rise which is due to climate change and its impacts [7]. Unfortunately, the inadequacy of financial resources to build the walls along the whole coast has left many of the coastal communities at the mercy of these incessant coastal floods.

Climate change and its attendant sea level rise, anthropogenic factors such as the construction of dams and ports, and sand winning can be said to be activities that are disturbing the stability of the coast. The instability is resulting in an increase in tidal action that leads to flooding and coastal erosion. Residents are putting in place measures that are aimed at reducing the impacts of tidal waves along the coast. These can be termed indigenous or local adaptation strategies. Indeed, the traditional approach to coastal flood management is based on local technologies developed over time [11]. In Africa, indigenous knowledge (IK) has been used in traditional medicine, agriculture, weather forecast, food production, water management, flood, and ecological management [12,13,, 13, 14]. In Ghana, indigenous knowledge has been passed down from generations to generations. These indigenous pieces of knowledge provide people, especially the indigenous ones with ideas for tackling local resource issues and help in their upliftment. Thus, local communities do not just stay idle for nature to decide for them. They build on their experiences and develop appropriate responses to the situation and in this case, coastal flooding. While studies on the impact of coastal erosion have largely looked at the changes in shorelines because of sea inundation [15,16,, 16, 17] and the use of models to show wave overtopping under different simulated conditions [18,19,, 19, 20], little attention has been given to indigenous adaptation strategies and impacts of the modern coastal flood defence walls on communities and people. This paper seeks to unravel the indigenous methods used to address coastal flooding in the eastern section of Ghana and review the effects the modern coastal flood defence walls by the government of Ghana are having on the people. It provides new insights into our understanding of how indigenous methods that were used to address coastal flooding in the coastal regions of Ghana have been relegated to the background or used when constructing new coastal defence structures along the coast and the effects the modern coastal defence structures are having on the people. In essence, the paper highlights the difficulties coastal people and communities are battling with to adapt to climate change-induced infrastructure projects.

2 Literature review

2.1 Global sea level rise and adaptation to coastal erosion

Due to climate change, sea levels are rising throughout the world and is wreaking havoc on the communities along the coast. The havoc being unleashed on these communities is in the form of coastal flooding. The impact of the intrusion of seawater leads to erosion of the land that is used by the people for fishing, farming, recreation, and housing. Houses and properties are being destroyed by sea intrusion which leads to the loss of people’s livelihoods as is the case in other developing countries [21]. Figure 1 is a framework showing sea level rise, coastal flooding, its impact, and sustainable adaptation strategies that is guiding this study. The framework shows that rise in sea level is leading to coastal flooding. The impacts lead to adaptation strategies in the form of retreat, accommodation, or protection. For the sustainability of these strategies, there is the need to mimic indigenous strategies in the construction of the coastal flood defence structures.

Fig.1
figure 1

Sustainable Coastal Management for Adaptation Source: Adapted from Jarungrattanapong and Manasboonphempoo

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Adaptation, as defined by the Intergovernmental Panel on Climate Change [22] is an adjustment in ecological, social, or economic systems that is done in response to actual or expected climatic stimuli and their effects or impacts. To IPCC [2,3,4] adaptation is defined, in human systems, as the process of adjustment to actual or expected climate and its effects in order to moderate harm or take advantage of beneficial opportunities. In natural systems, adaptation is the process of adjustment to actual climate and its effects; human intervention may facilitate this”. These definitions imply a change in attitude, processes, structures, or practices to accommodate or offset damages posed by the development, which in this study is the rise in sea level leading to the construction of coastal flood defence walls. This involves adjustments by people to reduce the vulnerability of communities, regions, or activities to climate change and variability [6].

For the achievement of sustainable adaptation [23,24,, 24, 25] in general and sustainable development goal three: ensure healthy lives and promote well-being for all at all ages, there is the need for adaptation to be integrated into our current development initiatives which are socially, environmentally, and economically sustainable. The framework proposes the taking of urgent action to combat climate change and its impacts by using all the approaches of adaptation in development interventions, especially the use of indigenous knowledge systems.

2.2 Measures that can be put in place to ensure coastal flooding along the coast

When infrastructure along the coast is being destroyed by wave action which is most of the time termed tidal wave destruction or coastal flooding, the typical response of most countries is to build hard infrastructure along the coast in the form of sea walls [15, 26, 27]. In the same way, a lot of studies have been undertaken on how strong these structures are to reduce coastal flooding and ensure sustainability [28, 29]. In Japan for instance, after the March 2011 tsunami disaster, studies carried out on coastal defence structures point out that seawalls are the most common technological responses to storm surges, but such responses not only changed the landscape dramatically but go a step further by affecting the daily lives of the population [29]. In the same vein, studies are being done on the development of prediction tools that can be used with accuracy to know how wave overtopping can take place on coastal defence infrastructures [18, 30]. These studies are providing significant references that are helping to optimize the design of coastal defence structures to control wave overtopping throughout the world.

Today, the debate on coastal defence structures is on sustainability measures to be put in place. Models are being developed and engineered for coastal areas to have living seawalls or eco-engineered seawalls [30,31,, 31, 32]. In localities where the structures are already in existence but are not serving its intended constructed aims, studies and models have been developed to retrofit the existing seawalls to enhance coastal resilience [33]. Even though, this paper is not aimed at ascertaining whether the sea walls are strong enough to withstand higher storm surge, it attempts to assess how the coastal defence structures constructed along the eastern coastal section of Ghana are benefiting the communities and people living along the coast where they were built. The attempt here is to understand how the structures are in line with the indigenous strategies and how they are benefiting the people who are the direct beneficiaries and whose infrastructures the coastal defence structures are to defend [34].

2.3 Measures being put in place to prevent coastal flooding along the coast of Ghana

In the Keta and Anloga areas, hundreds of homes close to the sea have been flooded and taken over by the sea. Thousands of people have been displaced in these communities after high tidal waves kept sweeping the coast on a persistent basis. The most affected towns in this district and municipality are Keta, Dzita, Akplowotorkor, Atorkor, Dakordzi, Fuveme to mention a few. These are mostly fishing communities. The government of Ghana has been at the forefront to combat these coastal inundations, not only in Keta but along the eastern to western shores of the country. Indeed, right from the onset of Ghana’s fourth republic in 1992, governments (National Democratic Congress (NDC) and New Patriotic Party (NPP) made it a national priority to alleviate the sufferings of the people within the southeastern coastal enclave from the impact of coastal erosion. This occasioned the construction of the Keta and Anloga coastal flood defence walls from 2000 and completed in 2004. Along the coast of the study area, one can see a stretch of riprap or armour rocks from east to west. Riprap can be said to be any large rock fragments (igneous in nature) of about 1 to 6 tonnes that are placed along the beach to protect it from the sea [35]. To Stamski [26] ripraps or seawalls are continuous, rigid structures on the coast that are aimed at lowering the impact of the sea on the coast.

Both soft and hard engineering measures were embarked upon in some parts of the project area to curb the incessant coastal erosion along the Keta sea defence project. Even though these hard engineering measures are very expensive and more intrusive [33], they are expected to provide a temporary to a long-term solution to the problem of sea erosion. An example of the hard engineering coastal flood defence wall is the use of groynes and revetments to stop coastal erosion. Groynes are barriers that extend from the beach, offshore into the sea [36]. Roest [37] however said groynes armour rocks are placed perpendicular to the beach to decrease longshore erosion and the transport of sediments. Along the coast of the study area, they are used to slow the loss of sand on the beach by longshore drift. About 16 armour rocks groynes were constructed along the coast of Keta and Anloga to reduce erosion of the beach. Through these structures, currents are diverted from reaching the beach. Groynes are made to reduce the erosion of lands on the shore but most of the time, they cause sediment starvation thereby shifting erosion of the coast further down drift [7]. Some beach nourishment was also undertaken along the Keta-Anloga coast and at Hlove. Armour rock revetments were mainly built along the Atorkor-Dzita-Anyanui sides of the study area as shown in Fig. 2A, B.

Fig. 2
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A: Revetments of the Keta sea defence project at Atorkor-Anyanui stretch. B: Fishermen pulling a net on the nourished beach without impediments from revetments

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In the case of Ada East District, the Ada Foah-Totope coastline was reported to be disappearing at a very fast rate of about 4 m a year [9, 38]. This dwindling of the coastline poses a threat to property, lives, and people’s livelihoods along the coast [39]. The government of Ghana came to the aid of the communities along the Ada coast by constructing the Ada coastal protection works. It was started in 2013 and completed in 2016. This project is intended to reclaim about 15 km of land from the sea. In this area also, about 15 groynes, beach nourishment, and protective barriers were expected to be constructed to prevent coastal erosion [40].

The next coastal flood defence project yet to be constructed along the eastern coast of Ghana is in the Ningo-Prampram District which is not within this study area. According to the President of Ghana, the project is aimed at protecting five kilometres of the coast which is being battered by sea erosion thus flooding and eroding the coast. Under this project, which was labelled Ningo-Prampram Coastal Protection Project, US$69 million was awarded to Messrs Bridge Global Consolidated Limited. This project is meant for the construction of armour rock revetment, groynes, and reclamation of land lost to the sea. This area is a prime tourist destination during the weekends due to its sandy nature but due to the incessant tidal wave inundation, the government is forced to construct the coastal flood defence wall along the beach. The claim is that, when the project is completed, tourism and fishing activities will be boosted which will translate into the protection of the livelihood of the fishing folks in the area. Other prioritized areas where sea defence walls will be constructed after the Ningo-Prampram Coastal Protection Project is completed are the Accra-Glefe, Anomabu, Axim and Amanful Kumah. Others are Cape Coast, Dixcove, Komenda, Mensah Guinea, New Takoradi, and Nkontompo coastal stretches which are all located west of the country.

3 Methodology

3.1 The study area

The study was conducted in communities that are close to the Volta estuary. The Volta River is a major water body that drains four countries in West Africa. The drainage basin of the river covers six riparian countries of Ghana, Togo and Benin in the east, Burkina Faso and Mali in the north, and Côte d’Ivoire in the west. The river was dammed at Akosombo to create one of the largest man-made lakes of the world in 1965. The river up north has the White Volta, the Black Volta, and the Oti River as its three main tributaries [41]. According to Goussard and Ducrocq [42] the river is a main source of sediment supply to the Gulf of Guinea coast. This is mainly due to its drainage of predominantly sandstone catchment area [43]. Indeed, the river has only one outlet to the sea at Ada Foah. In addition to sediment deposition by the Volta River, the coast is suffering from major coastal erosion [37]. The main characteristic of the Volta estuary coast is its narrow sandy beach barrier that fringes the coastal plain, the mangrove swamp and the Keta lagoon. This characteristic of the Volta estuary made Appeaning-Addo et al. [44, p. 2] to describe the Volta estuary which is our study area as a coast “bounded by a narrow shelf 15–33 km wide, and characterised by a fairly uniform, moderately steep shoreface with a gradient of between 1:120 and 1:150 down to 15 m, which is considered as the close-out depth for significant wave induced sediment movement”.

The study was conducted in one municipality and two districts in the southeastern part of Ghana. They are the Keta municipality, Anloga, and Ada East Districts. Even though Keta is a municipality, we shall refer to it in this study as districts for consistency. These districts are arguably the most affected in terms of coastal erosion and flooding in Ghana [10]. The area is about 149 km and stretches from the Keta (eastern section of Ghana) to Ada-Foah (western section). Please refer to Fig. 3. The justification for conducting the study in these communities is based on the following: Keta-Anloga and Ada East Districts benefitted from coastal flood defence projects. Also, these districts are among the most important tourist destinations in southeastern Ghana. The President of Ghana Nana Akuffo-Addo’s promise to the local communities is that upon the completion of the coastal defence structures, fishing activities will be boosted, the livelihood of the people living along the coastal defence structures will be improved and tourism and social infrastructures will be developed [44, 45].

Fig. 3
figure 3

Location of the Study Area

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3.2 Sampling design and sample size determination

In terms of methods, the study used several different data collection methods described by [46, 47] as “mixed methodology” or the “methodological triangulation” technique [48]. These mixed methods, as used in this study combined quantitative and qualitative research designs. Even though [49] said using mixed methodologies is not easy, others like [50], point out that the goals of methodological triangulation are for convergence and completeness as such it should be practiced. The decision to use these mixed methods was influenced mainly by the objectives of the paper [51], which are to ascertain indigenous strategies of coastal flood defence and the adaptation to new coastal flood defence walls. The useful qualities of the different methodologies could help to substantiate the reliability of the findings. Also, research methods and methodologies have changed over time and multiple methods are now being employed such as listening, seeing, recording, writing, asking questions, and reading in different ways to uncover different people’s experiences.

Neuman [52] points out that population is the large general group of people from which samples are drawn. It is the group that is of interest to the researcher, the group to which the researcher would like to generalise the findings of the study [53]. The study started with the quantitative survey in the three study districts before the research team proceeded with the collection of qualitative data. As already explained, the study used the mixed method research design because the researchers wanted to use the qualitative data to provide further explanation and insights into the quantitative survey results from the three districts.

The target population for the study was heads of households in the seventeen (17) study communities. The head of a household was chosen because they were in a better position to provide information about the indigenous and adaptation strategies to coastal flooding and how the household is coping with the constructed coastal defence walls. In places where the household head is not available, household members who can represent the head and were above 18 years were interviewed after they gave their consent in adherence to the ethical guidelines of the study.

A total sample size of 282 respondents (heads of households) participated in the survey out of the total quota sample of 300. Regarding the sampling design, different sampling techniques were used in arriving at the ultimate sampling units (that is heads of households). The first stage involved stratification of the target population into districts. Each stratum (district assembly) was then allocated a quota of 100 respondents. Approximately 33% of the proportion of the expected sample was allocated to each district assembly. This proportion was allocated to each district assembly because of the almost equal proportion of the total population of the districts; the absence of accurate population figures of each village that has experienced or is experiencing coastal flooding; the constraints that the research team expected to encounter in reaching the rural estuarian and coastal population; the poor transportation network and resource constraints. In the Keta and Anloga Districts, twelve (12) communities that have been experiencing tidal wave intrusion and where coastal defence structures were constructed were used for the survey. They are Keta, Adzido, Akplowotorkor, Anyanui, Atiteti, Atorkor, Kedzi, Dzita, Fuveme, Havedzi, Whuti, and Srogboe. In the Ada East District, which has Ada-Foah as its district capital, Totope, Pute, Anyakope, Kewunor and Azizanya were the communities sampled for the study.

In each of the seventeen (17) communities sampled in the three district assemblies, a multi-stage cluster sampling was used in sampling the respondents [54]. The first stage involved dividing each community into four clusters from which respondents were sampled. In other words, the communities were divided into north, east, west and south in order to have a representation of each unit in the community. The second stage involved numbering all households in the community. After the houses were labelled a systematic sampling procedure was used where the tenth house was picked for the administration of the questionnaire. At least four (4) respondents (heads of households) from the selected dwelling units in each of the four selected clusters in each community were interviewed. Table 1 shows the sample size of each district.

Table 1 Sample Size of Communities
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Hammersley [55, p2] defined participant observation as a research method where the researcher “participates, overtly or covertly, in people’s daily lives for an extended period of time, watching what happens, listening to what is said, asking questions; in fact, collecting whatever data are available to throw light on the issues with which he or she is concerned”. This method of data collection was chosen because of its inherent characteristic of directly observing what is going on in the field, unlike questionnaires and interviews, which are based on what the informant says to the researcher [48, 56]. Also, data were collected from real-life situations in the field, making it one of the most reliable empirical methods for data collection [57].

Regarding the qualitative data, a total of six (6) in-depth interviews were conducted with informants from the three study districts. They were all purposively sampled from each district. The six informants interviewed in each district comprised one planning officer and an assembly member in Keta, Atorkor and Totepe. The purposive sampling technique was used to select three communities that experienced tidal wave intrusion in the past for a Focus Group Discussion (FGD). The FGDs made up of eight (8) people were undertaken in Keta, Atorkor and Totepe due to the presence of revetments or groynes in these communities. The lead fisherman, two elders of each community, a farmer, two fish mongers and two fishermen were selected for the FGD. According to Hopkins [58], FGD is now widely accepted and used as a research method by human geographers, and for that matter social scientists in exploring various qualitative social and spatial events. It is an organized discussion, social gathering, and interaction [59]. It enables the study to gather attitudes, feelings, knowledge, and experiences of groups that could not be derived from questionnaires and observation. The discussions were recorded and transcribed. The themes are put together and used in the presentation of the results.

3.3 Data collection instruments

The survey data was collected using a structured questionnaire. The questionnaire was divided into four sections which included the demographic background or biodata of respondents, household flooding experience and indigenous adaption strategies, coastal erosion or tidal wave impact on livelihoods and benefits and adaptation to the sea defence walls. Some of the main questions asked in the questionnaire includes how coastal flooding has affected the respondents personally; the main cause of the coastal flooding in their community; the most important indigenous strategy that respondents and the community have been using to prevent coastal flooding before the coastal defence structures were constructed; the main factors people considered when choosing a particular adaptation strategy before the coastal defence walls were constructed; how coastal erosion is affecting or has affected respondents; the benefits being derived by the community from the sea defence walls; how the respondents in the communities are adapting to the presence of sea defence walls; how respondents are adapting to the absence of sea erosion; how the fisherfolks are adapting to the absence of large natural landing sites; the challenges being encountered in applying the adaptation strategies; whether respondents will move out of the community if issues associated with the coastal erosion persist, among others.

The qualitative interviews were conducted using an interview guide. The questions on the interview guide varied depending on the informant being interviewed. But in all, the information solicited from informants broadly captured household flooding experience and indigenous adaption strategies; coastal erosion or tidal wave impact on livelihoods and benefits and adaptation to the sea defence walls. The survey instrument (questionnaire) and FGD guides helped to address the objectives of the study.

As can be seen, this study uses methodological triangulation which can also be said to be mixed methods research [60] because the good sides of each of the methods are needed to aid in the confirmation of the findings. The use of mixed methods research in this paper also helps to improve the credibility, validity, and comprehension of the findings in this study [61]. The use of methodical triangulation in this study helps to offset the weaknesses of the use of quantitative research method with the strengths of the qualitative method. Finally, the mixed methods as used in this study helps to reduce the biases that might have occurred in sampling and procedural bias. This increases the validity and credibility of the findings.

3.4 Analytical procedure and ethics

The results are presented using graphs that show the percentage distribution of the responses from the 282 respondents of the seventeen (17) study communities. The questionnaire was analysed and inputted into excel and the results are presented in the form of tables, graphs, or charts. The results were analyzed using both descriptive and inferential statistics. Statistics like frequencies, percentages, mean and standard deviation of variables like indigenous strategies used to defend themselves against coastal flooding, benefits being derived from the sea walls, and adaptation strategies to sea walls were used. Factors like indigenous strategies, benefits being derived from the sea walls were used and the adaptation strategies have been ranked based on their means and standard deviations to best understand these factors.

Thematic content analysis was used to analyse the FGD and interviews. This analysis involved first the transcription of the interviews conducted with informants. After this, the transcripts were assessed to get a general overview and insight into the responses provided by informants. After the assessment of the transcripts, an identification of responses that fit under specified themes that the researcher is interested in was done. These themes include indigenous strategies used to prevent coastal flooding, benefits of the coastal flood defence structures and adaptation strategies against the modern coastal flood defence walls.

This study followed ethical principles [62]. The regulations governing social science research were rigidly applied in this paper. Ethics approval was sought from the institution which the researcher is a staff, and this was granted with certificate number SRGS/REC/0022. The underlying principles of Berg and Lune [63] were used to guide the research leading to the removal of personal data like names of respondents. This ensures their anonymity.

4 Results

This section of the paper presents the findings from the fieldwork done in the southeastern section of Ghana. It details the indigenous strategies used by the local people to combat sea disturbances, benefits being derived from the coastal flood defence structures, and current adaptation strategies being used by the indigenes to get used to the modern coastal flood defence walls. The presentation of the results starts with the demographic characteristics of the respondents.

4.1 Demographic characteristics of respondents

Table 2 shows the demographic characteristics of the respondents. The predominant age group of the respondents of this study is 36-45 representing 38% of the respondents. This is closely followed by the 46-55 age group. These age groups dominate this study because of the intention to solicit information from people who know about the indigenous methods of combating sea intrusion.

Table 2 Demographic Background of the Respondents
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In terms of occupation, Table 2 shows that the main day-to-day activity that serves as a source of livelihood for the respondents is fishing. Given that more people are engaged in fishing suggests that coastal erosion will have a severe impact on the lives of the people since their livelihoods will be affected. Table 2 shows that most of the respondents (176) are into fishing and its related activities. This translates to about 62.4% of the total respondents. This is closely followed by farming which accounts for 26.2% of the entire respondents. The third main economic activity in the study area is trading which employs about 5.6% of the respondents. In terms of educational attainment of the respondents, most of them, about 47.5% did not attain any formal education. In total, one can say that about 74.5% of the respondents have either no education or basic education.

4.2 Indigenous strategies used to prevent coastal flooding

The study ascertains the indigenous strategies that were used to control coastal flooding in the study area. Figure 4 represents the responses to the questionnaire. About 30.5% of the respondents pointed out that the main strategy they use to fight coastal flooding is to build far away from the shores and this ranked as number 1 indigenous strategy that the people have been using to prevent coastal erosion.

Fig. 4
figure 4

Indigenous Strategies to Prevent Coastal Flooding

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This response is closely followed by pouring of libation to the gods to prevent the occurrence of such an event. During the FGD, a participant in the Keta District pointed out that, it was the gods that allowed the sea to destroy their buildings. The gods might be angry with them that is why they allow the sea to come and destroy their buildings. It is also believed that the gods dwell in the sea and they get angry at inhabitants when they do something wrong. A participant during the FGD in Totepe points out that “for the gods to let us (the living) know of their anger, they destroy buildings that are close to the sea”. When this happens, the indigenes have no option other than to consult the gods or pour libation to pacify them. When asked why they build their houses close to the sea, people responded that it was due to mosquitoes. Houses are close to the shore because mosquitoes are not able to withstand the sea breeze. The lowest response, but not the least is raising the foundation of the buildings to prevent floodwaters from entering the buildings. This strategy is practiced mainly by the well-to-do in society who can afford the building materials in raising the building. This response was ranked as the 5th strategy. About 23.4% of the respondents said people do nothing to prevent coastal flooding while 10.61% and 9.9% point out that, they use sand to fill the coast and relocate respectively. For instance, one participant in Totepe pointed out that, “I used coconut leaves to build my fence walls so that when the waves come, it will only wash the compound of my residence, but I realized that the intrusion of the waves was becoming persistent, so I used sandbags to fill the compound to prevent the floods, but it continued”. Another participant from Keta pointed out that “I at times have to dig a trench and use sandbags to create a mini wall so that when the waves come, the wall will protect my house, but this did not work”. Another respondent also said they used coconut plantations on the coast to prevent the sea from eroding the land. The stories of people whose houses were destroyed in Dzita, Atorkor, Akplowotorkor, and Dakordzi in the Anloga District are similar. In Keta, a resident was able to point out a structure about 2 km deep in the sea by saying ‘that was where my house was but is now under the sea’. This assertion was corroborated by other residents in the area.

4.3 Benefits of the coastal flood defence structures

As can be seen in Fig. 5, the main benefit being derived by the community members is the absence of sea erosion that was rampant before the construction of the wall. Interview of key informants attests to the fact that the communities are now safe from the endless wave intrusion. The absence of coastal erosion occupies about 62.4% of the responses. This benefit scores the highest mean score of 56.4 and a standard deviation of 67.784. This means that the deviation between the average value or number is high.

Fig. 5
figure 5

Benefits of coastal flood defence wall

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The next major benefit being derived by people in the study area is the attraction of tourists to the wall. Livelihood activities are very important to the coastal folks and the respondents pointing out that the coastal flood defence walls constructed in the three districts under study are helping them to continue to enjoy or benefit from their livelihood activities is commendable in terms of climate change adaptation responses since the main livelihood activities of the people along the Gulf of Guinea are fishing and trading. Figure 5 shows the benefits being derived from the coastal flood defence walls.

In the case of the Ada-Foah area, respondents were very positive about the benefits of the coastal flood defence walls. They praised the way the walls had prevented the communities from being washed away. An official of the Ada East District assembly pointed out that the groynes were designed in such a way to allow sea creatures like turtles to nest on the beach. But at Azizanya, people were not happy with the way the structures were constructed. They claimed the coastal defence wall is not helping them because it had not been completed. Sea water at times does come to their community because they claimed the project was abandoned. Indeed, observation along the coast where the sea defence wall has not been constructed or abandoned show that tidal waves had been coming to communities that did not benefit from the coastal defence structures. The fishermen in this area cannot attest to whether turtles are now laying their eggs on the beach. Figure 6 shows the coastal defence structures along the coast of the study area.

Fig. 6
figure 6

Coastal defence structures along the coast of the study area. 1: Ada area sea defence structures made up of series of groynes. 2: Anyanui-Atorkor area sea defence structures (mainly revetments and groynes). 3: Keta sea defence structures showing revetments, groynes and reclaimed land. 4: Groynes along Kedzi-Adina coast. Source: [37]

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4.4 Adaptation strategies against the modern coastal flood defence walls

There are bad and good sides to every new development and the construction of the coastal flood defence walls along the eastern coast of Ghana is no exception. People are now being compelled to adapt to the new facilities. A very interesting response from one of the participants in the FGD in Ada was the joy of the absence of sea erosion along the coast due to the presence of the groynes. Figure 7 shows the revetment, groynes and nourished beach on the coast.

Fig. 7
figure 7

A Revetments constructed along the coast at Akplowotorkor. B Series of groynes constructed along the Dzita and Ada East coast. C Large Armour rocks constructed along the coast of Atorkor

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As can be seen in Table 3, over 57.4% of all the respondents said they have now adapted to this phenomenon which used to disturb them in the past. This response ranked number 1 with a mean of 56.4 and standard deviation of 60.05 which is high compared to the other responses. The main problem that the people are adapting to is the absence of natural landing sites. The revetments are placed above the high tide line, which prevents easy movement on the shorelines. These shorelines are the places where the daily catches are processed or sold. Their absence or shortening of the shoreline due to the presence of the revetments means they must adapt to its presence. They adapt by placing the nets along the road in Atorkor whilst in Totepe, they carry out their fishing activities close to the tide lines. This area also can be said to contain mainly groynes with few or little revetments. One fisherman in Atorkor lamented that ‘we cannot moor the boat and other fishing gadgets on the seashore anymore. All our boats are now in another village because of the presence of the revetments’. Usually, the boats are moored to the coconut trees on the coast, but the revetments prevent these activities from being practiced. The people now must adapt to mooring their boats and nets in other places. Adapting to the loss of landing sites was mentioned by about 14.2% of the respondents of this study and this has been ranked as number 2. Another adaptation strategy being used in the study is the non-availability of the beach. This was reported by about 10.6% of the respondents. During the FGD, one respondent attests to this by pointing out that, we sit on the sand on the seashore during the day or night to reflect on life, but we do not enjoy such a luxury here anymore. One must move down the beach itself where the sea wall is not present. Sunbathing is no longer present due to the revetments. Another respondent points out that, they now sit on the rocks that serve as the revetment should they want to enjoy the sea breeze. A respondent also laments that they no longer use their indigenous and traditional methods of fishing as can be seen in Table 3.

Table 3 Adaptation strategies to coastal flood defence walls
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This sandy beach is a source of tourist attraction and is used by people along the coast for recreation but due to the revetments, people can no longer enjoy the beach as they used to. Some also complain of a decrease in sea life along the shore. For instance, terrestrial isopods and benthic organisms cannot be found where the walls are constructed. Some of them like hermit crabs, shells of various snails, sea stars, octopi, clams, sponges to mention a few are no longer present on the shore where the walls are built. Few respondents amounting to 4.3% complain of the sea walls now being an eyesore to them. This response ranked as the least response occupying the 5th place.

5 Discussions

It has emerged from this study that, most of the respondents are within the age group of 36–45 and 46–55. The main reason that can be attributed to the predominance of this group in the study is that they are the main working-age groups in Ghana and West Africa for that matter. As pointed out in Ghana’s Population and Housing Census data [64], Ghana’s population has a youthful structure mainly within the 25–59 age group and this age structure is depicted in this study as well. The main occupation of the respondents as expected is fishing and this employs about 58% of them. This economic activity includes both fishing on the sea and in the lagoon. In the case of marine fishing, it is carried out along the coastline from Aflao in the east through to Keta, Ada-Faoh, and beyond. The freshwater fishing is however limited to the Keta Lagoon, the Volta estuary between Anyanui and Ada, and the lagoons surrounding Totepe and Ada-Foah. The high number of people deriving their main economic activity from fishing is not surprising since the study uses a purposive method to gather data from people living along the coast. Poultry farming is becoming a dominant activity being carried out on a large scale in the Keta municipality.

It is worth noting that, traders and the other group which altogether make about 10% of the respondents are directly and indirectly dependent on the fishing industry. For example, the fishmongers who are traders rely on the fisherman to do their business of smoking fish for sale. The traders also trade in buying from the fishmonger and sending it to the city for sale. It can therefore be concluded that about 95% of the respondents depend directly or indirectly on fishing for their livelihood. This, therefore, means that the impact of sea erosion on the fishing industry is likely to affect other occupations like trading and farming.

Indigenous knowledge can be said to be techniques, practices, approaches, or skills used by a certain group of people over the years to manage situations or events [65]. It is accumulated through learning, experiences, informal experiments, and at times through divine revelations of a given situation in a particular setting [14]. The findings in this study show that some people build houses far from the coast. The main advantage of building houses close to the coast is to prevent being bitten by mosquitoes. Houses close to the shore are not able to be infested with these annoying insects that inflict people with malaria. The sea breeze prevents mosquitoes from getting close to the houses that are along the seashore compelling fishermen to build close to the coast which are prone to destruction by the sea. The mitigating measure against seawater intrusion into houses is to build far from the shore. Another strategy that was reported is pouring of libation. Ghanaians and for that matter, Africans are highly religious, and this was seen in this study. Indeed, libation pouring to the gods is very common in Ghana and Africa in particular [66]. These findings are in line with what [67] reported in their study where rituals are performed to pacify the gods because it is believed that the sea erosion are sent by the gods to inundate their dwellings in anger at their transgressions. The pouring of libation to pacify the gods shows a clear sign of powerlessness in the face of this global environmental problem. Resorting to religion or the gods to salvage their desolate situation is something that is not peculiar to the coast in the face of disasters in Ghana. This observation is not meant to discredit the knowledge base of our traditional folk, but we all know that coastal erosion is the result of climate change and increases sea level rise.

The strategies of doing nothing and relocation are all part of the retreat strategy pointed out in our conceptual framework. This strategy does not mean they have not tried the other options. Retreat according to the respondents in Keta, Anloga and Ada East was the last resort after accommodation and protection. This finding is in line with what Jarungrattanapong and Manasboonphempool [8] found in their study in Thailand where households have individually applied three types of autonomous adaptation strategies of protection, retreat, and accommodation. It is important for climate adaptation strategies to deliver a lot of benefits in terms of equity and the ability of the system to mitigate the impacts that come from climate change. Findings from this paper reveals that people along the Southeastern coast of Ghana have developed series of defensive strategies that helped them to prevent the sea from inundating their communities. Some people said they use bags filled with sand to act as barriers between the land and the sea. This can be said to be a levee like structure which is similar to the modern revetments and groynes. The difference between the two however is the material that is used as the barrier and the scale. Sand can easily be washed away unlike the armoured rocks used in the revetments and groynes. These methods do not impede their livelihood activities of hauling fishing nets along the shores of the coast because they are small. The small size of these local structures, however, makes them vulnerable to sea encroachment. Nevertheless, the modern sea defence structures are preventing the sea from inundating some communities along the coast but these revetments and groynes are preventing the people from carrying out their daily routine activities of hauling the net close to their villages unlike their traditional small levee like structures.

The responses from this paper however clearly show that indigenous strategies started with accommodation, protection, and retreat as the last resort. These strategies are similar to what was proposed by Dronkers et al. [68]. In the case of Keta, Anloga and Ada East, a retreat is used only when all other strategies could not help in defending the land from climate change-induced sea erosion. People doing nothing can also be discussed within the context of financial vulnerability which reduces resilience and any means within them to salvage the situation. Again, the cost of relocation, which includes starting a new life elsewhere with family members, is another social and economic strain that prevents people from leaving their main place of abode.

People living along the southeastern coastal region of Ghana enjoy living close to the sea. This shows in the settlement patterns of the towns, villages, and residential buildings which are all positioned closer to the coast than they should normally be. This linear settlement pattern of communities along the coastal shores of Ghana is exposing them to coastal flooding because of their low-lying elevation [10]. It is true that sea level throughout the world is rising because of climate change however, anthropogenic activities like harbor construction and sand winning along the coast are also responsible [10]. Estimates in Ghana put the rise in sea level at a rate of between 3.1 and 4 mm/year [69] and is predicted to continue to rise in line with global trends [70]. The problem is that, will the sea defense walls withstand extreme overtopping? As far as this study is concerned, it is not possible to forecast that because it is not part of the aims of this paper. What can be said is that the groynes in the Ada East Districts are not helping with normal waves let alone when there are extreme overtopping events. For instance at Azizanya, the people claimed the project was abandoned because they are still experiencing sea inundation despite the presence of the groynes.

Ghana’s coast is retreating at an alarming rate compelling the government to start constructing coastal flood defence walls. Indeed, erosion of the coast is not happening only in Ghana. Other West African countries like Nigeria, Benin, Togo, Cote D’Ivoire, Senegal to mention a few are suffering from coastal erosion [15,16,17]. The coastal flood defence walls are benefiting the beneficiary communities in the sense that, sea erosion is no longer disturbing them as they used to, but this is at a cost. Tourists are now being attracted to the area due to the walls. The government will not be able to construct armour rock coastal flood defence walls along the entire coast of the country since it is not only Keta and Ada-Foah that are suffering from tidal wave-induced coastal erosion in Ghana. The shores in Accra, Central, and Western regions are all being battered by coastal erosion [71]. This calls for local solutions.

The main disadvantage of the coastal flood defence walls along the southeastern coast of Ghana is the lack of landing bays or sites for fishing in the areas where the boulders have been placed. People are thus complaining of placement loss or access issues as far as fishing is concerned. Most of the people in the communities seem to be happy with the walls because they are no longer suffering from coastal erosion. Overtopping of the coastal defence structure is happening mainly in the Ada East District. Communities like Azizakpe, Azizanya, Lolonya and Kewunor are experiencing overtopping of their sea defence walls because they claimed the walls have been left at the mercy of the weather. Currently, the armour rocks look like they have been dumped on the coast without any planning and maintenance leading to these communities to be experiencing flooding.

Some of the respondents are still not happy with the unavailability of landing bays close to their houses as they used to. It should be noted that the preservation of beachfront buildings is not the main reason for the construction of the seawalls. This is because the President during the sod-cutting ceremony also reiterated the need to attract tourists to the areas and the continuation of livelihood activities. Indeed, the tourists are being attracted but they do not have the natural habitat that they do enjoy, which is sitting on the sandy golden beach. It is of interest to note also that the sea walls are protecting only the land that is immediately behind them. It offers no protection to other beaches along the remaining coast. That is why after constructing the Keta coastal flood defence project and that of Ada-Foah, the Ningo-Prampram project is also about to be constructed. The argument here is that the walls are protecting the land immediately behind it but causing havoc in other areas. This is consistent with studies like those of [15, 72].

Climate change and its antecedents of global ocean warming puts human beings in an unavoidable reality that new solutions are needed to solve these myriads of problems on earth. The fact is that man has been existing on earth for a long time especially through the different planetary years that rolls by. The main survival strategy that has transformed human beings to this age of scientific knowledge was the use of indigenous traditional strategies. These indigenous knowledges are not passive but still active. However, it shows that we must consider it alongside the best scientific understanding of priorities needed to prevent social and ecosystem collapse [73].

Also, sea walls are degrading the beaches as far as some community members are concerned. Revetments being an eyesore is not an isolated concern in the southeastern section of Ghana. Kelly [74, p5] asserts that “scientists, coastal residents, and most coastal engineers (though not all) agree that seawalls degrade beaches”. The construction of the coastal flood defence walls in the study area resulted in the loss of a place called the beach (placement loss) where people usually sit and think of the next cause of action and their lives as a whole [75, 76]. It is argued here that, the values of the construction of the coastal defence walls along the eastern coast of Ghana are high and the people are benefiting from the walls, but some people are still not happy with the project. In a sense, constructing armour rock coastal flood defence walls in the form of groynes and revetments is not sustainable to them. Social sustainability is not being ensured. The beach with its golden sand is no longer serving the people who the armour rock wall is supposed to serve. Also, the fact that terrestrial isopods and benthic organisms cannot be seen is a source of worry. The wall is now an eyesore to some people. Even though these people are on the minority, these environmental concerns can be attributed to people who value a place and are connected to nature.

Connection with nature has been shown repeatedly to benefit human wellbeing and predict pro-environmental behaviours. Therefore, reconnecting people with nature can act as an antidote for key sustainability challenges. Society’s disconnection from nature has been identified as a root cause of unsustainability [77] and climate change which is now affecting coastal inhabitants. This is seen in the people’s recourse to pray to their gods when the sea intrudes into their houses, destroying or washing them away in the process.

6 Conclusions

For many years, people living along the coastal regions of Ghana have been using indigenous strategies to prevent the sea from flooding and destroying their buildings, but these strategies are no longer working due to the intensity of the impacts of climate change and rising sea levels [14]. This led the government of Ghana to build coastal flood defence walls to prevent coastal flooding. It was revealed in this study that, the coastal flood defence walls constructed by the Ghana government are helping communities by preventing flooding but the sustainability, especially social sustainability of the strategies is not being assured because they do not mimic the indigenous strategies of coastal protection and sustainable development. To some people in these communities, losing the shoreline and the beach means losing their source of income or livelihood. This study is the first to provide new insights into an understanding of indigenous methods that were used to address coastal flooding in the eastern section of Ghana and the effects the modern coastal defence structures are having on the people. This study points out that coastal flood defence walls are meant to control the erosion of the shoreline, and the walls are serving this purpose for now apart from a few cases in Azizanya and other communities in Ada East District. The sustainability of livelihoods is at stake and this should be fundamental to solving the perennial coastal inundation. This is because indigenous local experiences can serve as useful indicators of climate change [78] and how it is being solved for resilient adaptation. This is because, after the construction of the coastal flood defence wall, people find it difficult to adapt to it. Also, the method of using armour rock revetments and constructing groynes along the coast is not known to them but serves as a barrier to fishing thus unsustainable.

Also, finding from this paper show that indigenous knowledge of protecting the coast from sea-level rise and shoreline change is not enough to successfully curb sea erosion along the coast of southeastern Ghana. Also, the use of current scientific knowledge in sea defence wall construction is good but is not helping with adaptation and resilience of the coastal people. It is recommended here that traditional knowledge of sea defence wall construction or using levees or raising the shorelines should be combined with the latest scientific advances in marine engineered seawall construction, monitoring, and restoration. Combining these two knowledge systems could offer coastal communities and countries with a way forward in combatting such difficult environmental challenges. This study is calling for the indigenization of science in marine wall construction. Through the integration of traditional knowledge and scientific knowledge, an adaptive situation will be created which will help build climate resilient infrastructure of coastal communities.

Nature-based coastal flood defence walls can also help in protecting the coast from sea erosion [17, 30, 31, 79]. It is recommended here that, the government of Ghana should try and construct coastal flood defence walls that are in line with the age-old strategies used by the people to defend themselves against sea erosion. Less technologically advanced designs can be implemented at the local level, using local knowledge and strategies. This is because the construction of a coastal flood defence wall in one area will have repercussions in other areas [15, 39]. Since it is not feasible to construct revetments in all the communities at risk along the shores of Ghana, prudent strategies should be adopted to manage the coast and one is the use of soft engineering approaches like beach nourishment and creating sand dunes. Retrofitting of the existing coastal defence walls along the coast of Ghana will not only provide great potentials for enhancement of the climatic resilience of this coast [33, 80] but also go a long way to ensure sustainable livelihood of the fishing folks along the coast. Alternatively, these revetments can be done in such a way that will serve as a fishing harbour, which can sustain the livelihoods of the fishing folks along the coast unlike the haphazard manner they looked along the coast.

It is concluded here that, there are similarities and linkages between the indigenous methods of sea defence strategies in the study area and what is being done by the government which can be said to be the scientific and advance coastal defence structures in the form of revetments and groynes. These similarities can be said to be prerequisite for knowledge sharing and integration [49, 81] in coastal defence along the coast of Ghana and West Africa as a whole. This knowledge integration will help in developing resilient coastal defence structures and adaptation. This study therefore agrees with Agrawal [82] that there is the need to preserve, use or merge indigenous knowledge with modern science, particularly in Africa because it is part of the daily activities of the people. To this study, the indigenous strategies can be said to be socially sound and environmentally friendly but were not used in the development of the modern sea defence structures. This might be due to the cost involved. This study therefore proposed a sustainable approach to sea defence wall construction through the integration of indigenous knowledge systems of coastal defence strategies and modern costal defence strategies. This integration can be done by covering the revetments and groynes with sand from the land and plants planted on them. The armour rocks can be eco-retrofitted by covering them with sand and grasses planted on them to absorb carbon dioxide. This is because studies show that “eco-retrofit effectively contributes to the reduction of maximum wave-by-wave overtopping” [78, p. 6]. There is the need to restore the coastal ecosystem by planting trees like mangroves and coconuts along the coast. Mangroves are natural ways that can be used to trap sediments along the coast to help stabilize the coastline. This cannot be planted on the shorelines, but grasses will do this work. These grasses prevent overtopping and erosion by the sea waves and therefore can be used as barriers. In addition to plant-based sea barriers, sand should be dredged from the seafloor and used to nourish the coast as done in some parts of Keta and Kedzi to enable the fishermen along Dzita and its environs to continue to undertake their traditional fishing.

The technology in the Netherlands and Belgium of using sand motors should be applied in Ghana to nourish the coast with sand at a cheaper cost rather than boulder revetments. These suggestions are in line with adaptation to climate change measures of infrastructure development. They should be built in such a way that will ensure sustainable development. Sand nourishment can be done on the armour rocks for plants to be planted on them for easy adaptation. It is important to design and implement less technologically complicated methods by using local strategies and knowledge of coastal flood defence management. Adopting this approach will reduce the investment and money needed to construct other coastal flood defence walls in the country.