Wetlands are a valuable natural resource of considerable scientific interest because they are associated with biological diversity, important ecosystem functions and processes, and useful, economically viable products ( Mitsch & Gosselink, 1993 ). Floodplains play a vital role in preserving biodiversity and providing environmental services to human populations ( Di Baldassarre, 2012 ). The Inner Niger Delta (IND) in Mali, is the biggest floodplains in Africa, covering four million hectares and supporting over one million herders, fishermen and farmers ( De Noray, 2003 ; Zwarts et al., 2005 ). IND wetland represents a vast natural resource that continues to attract many people to live in and around the delta ( Liersch et al., 2012 ; Zwarts et al., 2005 ). Since the beginning of the drought in the early 1970s, the IND wetland has been faced with a problem of sustainability of renewable natural resources. The management of these fragile resources, by a population with diverse practices (agriculture, livestock, fishing) in order to ensure their sustainability, involves multiple decision-making criteria and constraints ( Kuper et al., 2002 ). Wetlands provide a wide range of ecosystem services that contribute to human well-being, such as fish and fibre, water supply, maintenance of water quality, climate regulation, flood regulation, coastal protection, and recreation and tourism opportunities ( Millennium Ecosystem Assessment, 2005 ). Wetlands are also critical for the conservation of biological diversity. There is increasing recognition of the value of these functions and other ecosystem services provided by wetlands. In particular, wetlands are vitally important for providing the regulating and supporting ecosystem services that underpin water resources management, and can thus be considered as essential components of overall water infrastructure ( Emerton & Bos, 2004 ). Liersch et al. (2012) investigated the impacts of climate change and upstream water management on food production in the IND under two population growth scenarios. In their article, the focus was on the assessment of external impacts on the carrying capacity of the IND with regard to the number of people who can be supported by the ecosystem service related to rice production. During and after the rainy season in Mali (June–October), large area of the IND are flooded. Naturally, these floodplains provide vital habitats supporting livelihoods in fishing, farming, and stock farming ( Zwarts et al., 2006 ). Being already subject to large interannual variations of rainfall, particularly in the Niger and Bani headwaters, these habitats are additionally threatened by a variety of anthropogenic pressures and unsustainable uses ( WWF, 2008 ). All activities in the area of IND wetland are highly depending on flooding patterns and duration, water depths, and the management practices. Hence, all factors that influence the inflow into the wetland. The spatio-temporal inundation patterns within the IND wetland have an impact on food production and food security in the wetland area. Mali’s population is projected to increase from 14 million (2011) to 40 million people in 2050 ( van Vuuren et al., 2007 ). Food and energy demand, as well as improving living standards, will increase the pressure on natural resources. Thus, studying the sustainability and the vulnerability of the IND wetland is as important to insure the demand of the growing population. The present study seeks to provide a comprehensive review of trends and prospects of climate-based research on the IND wetland during the last three decades.

The current study used the Scopus databases to retrieve relevant documents on the wetland situated in the Niger river in Mali—namely, the Inner Niger Delta. Scopus is a typical online academic database that has a great impact on academic literature due to its access to a wide range of journals and sources in all kinds of knowledge areas ( Baas et al., 2020 ). A literature review was conducted on the Scopus platform in order to assess the publication pattern relevant to IND wetland. The approach consists of conducting a scientific mapping of research topics related to the IND wetland in order to understand thematic trends, developments, the nature of collaboration networks and general narrative in line with the biggest wetland in Africa. Bibliometric analysis was defined by Pritchard as the application of mathematics and statistical methods to books and other media of communication ( Pritchard, 1969 ). Two widely used bibliometric methods are citation analysis and content analysis. Citation analysis implies a relationship between citing and cited works in a particular research area and allows one to identify core literatures, journals, countries, etc., ( Pilkington & Meredith, 2009 ). Publications using bibliometric methods have grown over the years. Yet, large bibliographic datasets have made classic review methods cumbersome and impractical ( Ramos-Rodrígue & Ruíz-Navarro, 2004 ). The search term used was “Inner Niger delta Wetland” and an analysis was performed through Scopus Science, which provides information such as the number of publications per year, the countries in which studies have been published and, the authors who have published the most papers on a particular subject. In total, 223 articles were initially found and 153 publications were finally selected on May 11, 2023. The dataset extracted from Scopus for the bibliometric analysis was downloaded as bib (BibTeX Bibliographical Database) file and the Bibliometrix package in R is used to process the information. These extracted data comprised much information such as the author’s name, author affiliation, article title, keywords, abstracts, and multiple citations.

The IND is one of the largest floodplains in the world and is located in the Sahelian Zone in Mali in West Africa. Food production in the IND encompasses mainly three sectors: agriculture, fishery, and livestock. The agricultural system in the IND is therefore very complex and the multiple usage of natural resources is based on community rules and customs that have shaped the way in which societies have administrated this area for a long time ( Marie et al., 2007 ; Moorehead, 1997 ). Some upstream dams and irrigation structures are already in place, while more are at the planning stage. The infrastructures aim to increase economic development and food security ( Haque et al., 2019 ). This study can help researchers better understand how the subject has evolved over time and varied from one place to another place.

The whole of West Africa has been faced with extreme climate variations over the past 5 decades with extended extreme drought conditions during the 70s and 80s ( Lebel & Ali, 2009 ). Inner Niger Delta research has attracted the attention of researchers over the past two decades, with several annual publications, which increased from 1 in 2000 to 11 in 2021 and peaked in 2013 and 2018 with 15 publications. Indeed, since the beginning of the 20th century, there has been a decline in the trend of precipitation in Mali ( Funk et al., 2012 ). This increasing number of publications shows a trend of continued growth, demonstrating that more and more researchers have become interested in this area of research. A total of 51 countries had published in this research area. Among these countries, Europe is the most represented by France and Germany, which are led by more published articles. France is of great interest with approximately 20.26% of the total number of articles published. Followed by Africa represents by 19 countries out of the 51 countries; nevertheless, Nigeria and Mali with respectively 9.80% and 5.22% of the articles published. The current research situation exhibits the weak collaboration among regional institution to undertake scientific research with local perspectives. However, research on the Inner Niger Delta is characterized by the limited availability of literature and databases according to the Ministry of the Environment (2002 annual report). In the same perspective, according to ( Neal et al., 2012 ; Kuper et al., 2003 ), despite the availability of global numerical models, and the extent of their field of application and in-depth studies carried out in the field, knowledge on the state of the environment are still insufficient. Knowledge of floodplain topography remains insufficient to properly model floodplains. Therefore, with all of the above, more similar studies reinforce the need for continued research and knowledge generation as the Inner Niger Delta contributes significantly to food security and employment in West Africa, particularly in Mali. The research on the Inner Niger Delta is multidisciplinary which combines climate, agriculture, livestock, fisheries, ecosystems, environment, bioresources technology, biochemistry, and plant and soil science. Given the economic importance of the inundation areas, there have been several studies examining the dynamics of the flooded areas. The techniques used include the generation of time series of inundation maps using satellite imagery ( Berge-Nguyen & Cretaux, 2015 ; Ogilvie et al., 2015 ; Zwarts et al., 2005 ; Mariko, 2003 ), the development of empirical functions that linked the water level at key stations to the inundation extent ( Mahe et al., 2011 ; Zwarts et al., 2005 ; Mariko, 2003 ), and numerical simulations using numerical models ( Haque et al., 2019 ; Schröder et al., 2019 ; Fleischmann et al., 2018 ; Haag, 2015 ; Neal et al., 2012 ; Dadson et al., 2010 ). The evolution of the keywords during the study period revealed that the Inner Niger Delta contributes to the achievement of sustainable development objectives in the West African region. The current focus of studies on the Inner Niger Delta has shown that more researchers are interested in hydrology, agriculture, livestock, fisheries and the impacts of climate change on the flooded area of the delta. Having adequate knowledge of the characteristics of observed and future changes in flood and rainfall extremes is important for developing appropriate adaptation measures to minimize the impacts on society and the environment. This is particularly important because extreme rainfall is expected to intensify with global warming over large parts of the globe as the concentration of atmospheric water vapor which is a source of rainfall increases in proportion to the saturation concentrations at a rate of about 6% - 7% per degree rise in temperature according to the thermodynamic Clausius–Clapeyron relationship ( Ingram, 2016 ; Allen & Ingram, 2002 ).

The IND is considered as a hub of human activities, including agriculture, fishing, transport, and tourism. The Delta plays an important role in promoting sustainable development for food security, water management, and the environment.

The current research situation on the IND wetland is dominated by results from developed countries research institution which claims for more efficient collaborations among regional institution in Africa to undertake scientific research with local perspectives. Keyword analysis of relevant publications illustrates the importance of the topic, and analysis of cited references highlights the starting point for further discussion. The results reveal that the topic of research has received increasing attention and that the number of annual publications has followed an upward trend. Although many research papers using the IND were found, very few of them took into account the impact of climate change and the hydrology of the area. They focused on agricultural productivity, fisheries, livestock and water levels. Thus, one of the main challenges of research on IND is therefore to pursue research projects by applying them in the impact of climate change in the short and long term period and the hydrology of the area. In order to assess the potential of the IND in achieving the objectives of sustainable development in West Africa in general, particular in Mali. Many aspects could be considered for the future direction of effective mitigation of climate change impacts. It might be interesting to understand the economic potential of the IND. However, many factors influence the development of activities in the area, such as insecurity, the lack of training of farmers to adapt to the evolution of their trades and the management policy of the area. Therefore, even with an increased number of publications in recent years, further research is still needed to understand the evolution of IND in the short and long term as well as the aspects necessary to optimize the economic potential, improve sustainability and mitigate the impacts of climate exchange.

The authors wish to acknowledge the scholarship and financial support provided to the First author by the West African Science Service Center on Climate Change and Adapted Land Use (WASCAL) through its graduate school program on West African climate systems at FUTA, Nigeria. Acknowledgement to the International Science Program (ISP/IPPS) through its granted research group MAL:01 for providing research facilities and workspace for this study.