Climate change and water-related threats in the Indian Sundarbans: food security and management implications

ABSTRACT

Based on a desk review and three rounds of the Delphi method, this study examines the impacts of climate change-induced water-related threats on food security in the Indian Sundarbans, and develops management strategies to address the issues. Results show climate change, through its impacts on water, has lowered agricultural output, endangered traditional livelihoods, reduced access to food, and affected food utilization by impacting freshwater availability and creating health hazards. In addition, intensified weather extremes are likely to threaten food security further. A combination of local-level adaptation measures and global-level mitigation initiatives is necessary to ensure food security in this region.

KEYWORDS:

• Climate change
• water
• food security
• Sundarbans
• West Bengal
• India

Introduction

Coastal areas are among the most vulnerable regions to the impacts of climate change, where the effects of sea-level rise and extreme weather events are exacerbated by the high population density and socio-economic vulnerability of the local communities (Toimil et al., 2020). The Indian Sundarbans, a vast deltaic region located at the apex of the Bay of Bengal, is one such area that is experiencing significant impacts of climate change (Sánchez-Triana et al., 2016). This region is a complex network of mangrove forests, tidal creeks and estuaries, which supports rich biodiversity and provides a range of ecosystem services to the local communities (Halder et al., 2021). However, the region is facing several water-related threats (WrTs) due to the impacts of climate change that jeopardize the ecological integrity of the area and pose severe challenges to the livelihoods of about 4.43 million people living there (Das et al., 2023; Zaman et al., 2018).

The intensity of cyclonic events in the Indian Sundarbans delta (ISD) has increased due to climate change (Figure 1), resulting in the displacement of millions of individuals and the flooding of hundreds of hectares of land with saltwater (Basu, 2022). These intense cyclones and several geophysical and geo-hydrological factors have made the region highly susceptible to storm surges and subsequent floods (Chaudhuri et al., 2021). The ISD is also experiencing rising sea levels, leading to salinization, permanent inundation, and waterlogging in many islands and low-lying areas (Das et al., 2021; Sahana et al., 2019). The changing behaviour of the monsoon (Figure 1) has further caused frequent droughts and floods in the region (Dubey et al., 2017; Ghosh & Mistri, 2020). The depletion of mangrove cover has worsened the effects of these climatic disasters, with the loss of 107 km² of mangrove area between 1975 and 2013 in the ISD (Akhand et al., 2017).

Figure 1. Climate change impacts in the Indian Sundarbans: (a) trends in summer and (b) winter temperature; (c) monsoon precipitation anomalies; (d) monsoon precipitation trend (computed using CRU TS v. 4.06); (e) major weather events that impacted the Sundarbans in the period 1988–2020 (TD = tropical depression, TS = tropical storm, H1–H5: Category 1–5 cyclone based on the Saffir–Simpson scale) (computed using the information available on Sharma et al., 2022); and (f) maximum sustained wind speed in km/h of the major events during 1988–2020 coded as C1988–C2020 (computed using the information available on Sharma et al., 2022).

Such impacts of climate change on the hydrological systems of the ISD may have significant consequences on food security in this region. The delta supports a large population of fish, crabs and shrimps, which are the primary sources of protein for the local communities (Bandyopadhyay et al., 2022; Ghoshal et al., 2019; Mandal et al., 2013). Also, agriculture is an essential source of livelihood for the delta’s inhabitants, and paddy cultivation is the most widespread form of agriculture in the region (Mandal, 2019). The changes in hydrological systems may lead to changes in crop yields and fish population, which in turn can affect food availability, access and affordability, leading to food insecurity (Mbow et al., 2019). Besides, the degradation of natural resources as a result of climate change can have far-reaching social and economic impacts. As natural resources such as water and arable land become scarcer, it can increase migration and conflicts over access to these resources (Burrows & Kinney, 2016). This, in turn, could create social tensions and exacerbate existing political and economic instabilities. Therefore, it is imperative to comprehensively investigate the effects of climate change on water resources in the ISD and analyse their potential impact on food security.

The majority of previous studies on ISD have so far concentrated on how environmental changes, for example, climate change and hydro-physiographical changes, influence livelihoods and the coastal ecosystem (e.g., Akhand et al., 2017; Chatterjee et al., 2015; Chowdhury et al., 2016; Das et al., 2021; Hajra et al., 2018; Mahadevia Ghimire & Vikas, 2012; Padhy et al., 2021). These studies, however, only seldom explored the challenges to food security posed by water and climate change and failed to simultaneously consider all four dimensions of food security (availability, access, utilization and stability). Besides, some studies have shown that inadequate mitigation and adaptation measures are exacerbating hunger risk in the region (Edmonds et al., 2021; Ghosh et al., 2018; Guha & Roy, 2016). However, a comprehensive study that integrates the various impacts of WrTs on all four dimensions of food security (availability, access, utilization and stability) and identifies strategies to address them is still lacking. To fill this gap, this study conducts a review to explore how climate change-induced WrTs affect all four dimensions of food security in the ISD. It also seeks to identify potential management strategies to enhance food security in the face of these challenges. By understanding the impact pathways of WrTs on food security, policymakers can make better-informed decisions to address food security challenges in the region.

The rest of the paper is organized as follows. The next section initiates with an explication of the notion of food security by providing its definition and an overview of how WrTs can impact its four pillars under climate change. The third section delineates the research methodology, incorporating the literature review procedure, secondary data sources, expert selection and the processes required to execute the three rounds of the Delphi method. The fourth section illustrates the findings from the desk review, along with the expert consensus on the identified impacts of WrTs on food availability, access, utilization and stability in the ISD under climate change. It encompasses a range of management options that the experts designated higher scores from the perspective of climate change and food security. Finally, the last section offers a synthesis of the study, its limitations and future directions for research.

Food security in the context of climate change and water-related threats

The United Nations Food and Agriculture Organization (FAO) has defined food security as a state where all individuals have consistent access to sufficient, safe and nutritious food that meets their dietary needs and preferences, allowing for an active and healthy life (FAO, 2003). This definition emphasizes four key dimensions of food security: availability, access, utilization and stability (FAO, 2003, 2006). Availability refers to the supply side of food, which is influenced by production, processing, distribution, sale and exchange; access refers to the ability to acquire food, including the effects of pricing; utilization relates to the way in which the body absorbs nutrients in food, which may be influenced by cooking and health; and stability refers to the sustainability of the other three pillars over time without disruption (FAO, 2003; Mbow et al., 2019).

Climate change poses a significant threat to all four dimensions of food security through its impact on water (Figure 2), which is not only crucial for human survival as a drinking source, but also plays a critical role in crop production, irrigation, transportation, processing and overall resilience of the food system (Biswas & Tortajada, 2015; Kadiresan & Khanal, 2018). For instance, WrTs resulting from climate change, such as droughts, floods and storms, can significantly impact food availability by reducing crop yields and disrupting food supply chains (Devereux, 2007). Droughts can lead to water scarcity, causing a decline in crop production, while floods can damage crops, cause soil erosion and result in the loss of livestock, further reducing the availability of food (Parida et al., 2018). Livestock in water-deficient environments become weak and undernourished, which decreases the production of meat, eggs and milk and increases their susceptibility to parasites and infectious diseases (Gitz et al., 2016). Additionally, climate change-induced changes in ocean temperatures and acidification can negatively affect fish stocks, reducing the availability of an important source of protein for many communities (Brander, 2010).

Figure 2. Simplified diagram showing the impact pathways of climate change-induced water-related threats for food security.

Regarding food accessibility, WrTs under climate change can impact it by disrupting agricultural trade and transportation systems through flooding, storm surges and cyclones, which limit physical access to food (Ingram, 2011). These threats can also reduce household income, especially for those dependent on primary sectors, making it difficult to access food reliably (Omar et al., 2021). Additionally, extreme weather events such as floods and cyclones can displace people, making it challenging for them to secure employment and access to food (Mukherjee & Siddique, 2018). In terms of food utilization, climate change frequently exacerbates WrTs through access to potable water and health implications in terms of the occurrence of waterborne diseases, both of which impair health and the ability to feed children and dependents (Costello et al., 2009). The availability and safety of food can also be jeopardized by reduced water availability or increased water contamination due to floods, further impacting health (Campbell et al., 2016).

Overall, the stability of food availability, access and utilization is expected to decrease due to the increased severity and frequency of extreme weather events and resulting WrTs (Mbow et al., 2019). This could lead to a reduction in freshwater resources, widespread crop failure, increased migration and conflicts, higher food prices and instability in agricultural incomes, ultimately threatening the long-term stability of food security (Kogo et al., 2021).

Methodology

The methodology of this study comprises two primary components: a desk review and a Delphi study (Figure 3). The desk review involves an exhaustive search through grey and peer-reviewed literature to collate information and knowledge concerning the effects of climate change-induced WrTs on the four dimensions of food security in the ISD. On the other hand, the Delphi study involved a three-round expert knowledge-based approach to identify management strategies for achieving food security. It is a structured and iterative process in which experts with diverse experiences and perspectives on a specific topic of interest actively participate to reach an agreement (Linstone & Turoff, 1975). Further, it helps to address a range of social influences that could affect group-based decision-making (e.g., groupthink, halo effect, egocentrism, dominance; Orr, 2021). The details of the Delphi process are elaborated on in the subsequent section.

Figure 3. Methodological flow chart.

Desk review

The review began with identifying grey literature sources, such as conference papers and proceedings, government documents and reports, research reports, working papers and blogs, using the widely used search engine Google (https://www.google.com/). The study also accessed pertinent theses and dissertations from ‘Shodhganga: a reservoir of Indian theses @ INFLIBNET’ (https://shodhganga.inflibnet.ac.in/). A systematic literature search was then carried out on two academic search engines, Scopus and Google Scholar. In Scopus, a title–abstract–keywords search was performed in February 2022 using the search string: ((‘Climat* chang*’) AND (‘Sundarban*’) AND (‘India*’)). Meanwhile, in Google Scholar, relevant studies were identified using various combinations of keywords related to climate change, WrTs and different dimensions of food security, including ‘climate change impacts on agriculture at Indian Sundarbans’, ‘vulnerability of the Indian Sundarbans’ and ‘sea-level rise and livelihood threats at Indian Sundarbans’, among others. The review also included checking the reference and citation list for additional relevant literature. After a thorough screening, a total of 70 studies that corresponded to the study’s objectives were incorporated into the review. The reference section of the supplemental data online presents the complete list of studies reviewed.

Delphi study

The Delphi study was conducted in three rounds between April and May 2022 to determine effective management strategies for attaining food security at ISD. The initial and vital step in the Delphi approach is the selection of experts (Powell, 2003). In this study, following Allen et al. (2019), experts were defined as individuals who possess knowledge or have access to information relevant to the issues under investigation, as confirmed by verifiable means such as their professional position, discipline or publications. A list of potential panel members was compiled by searching scholarly databases (Scopus and Google Scholar) and the authors’ networks, consisting of experts knowledgeable in the impacts of climate change and WrTs on food security in the ISD. A total of 18 potential panel members were invited via email, which included details about the research aim, protocol and ethical clearance, allowing potential participants to self-assess their expertise and suitability for the study.

Seven experts ultimately agreed to participate, representing diverse academic backgrounds, including agriculture and fishery (n = 2), geography (n = 2), economics (n = 2) and sociology (n = 1). In Delphi studies, the number of experts can range from two to 184, and a statistically representative sample size is not necessary as the study’s outcome depends on the quality of experts, not their numbers (Powell, 2003). A minimum panel size of seven is appropriate for Delphi, according to Linstone (1978), and therefore, the present study’s panel size falls within the accepted range. Furthermore, pooling inputs from different disciplines allowed for a diverse knowledge base, enhancing the study’s outcome.

First round of the Delphi study

In the first round, the panel of experts was acquainted with the impacts of water-related challenges induced by climate change on the four dimensions of food security in the ISD, which were identified from the desk review. The experts were then requested to indicate their level of agreement on a five-point Likert scale, that is, (i) ‘strongly agree’, (ii) ‘agree’, (iii) ‘neutral’, (iv) ‘disagree’ and (v) ‘strongly disagree’, regarding the identified impacts. Additionally, they were asked to provide open-ended responses to reflect on potential management strategies for attaining food security. If the experts felt that they lacked the requisite knowledge to comment on the suggested strategies, they were given a choice to abstain.

Second round of the Delphi study

In the second round, the responses obtained from all experts during the first round were compiled, and any recommended management strategies that were similar or overlapped were consolidated into a single strategy, as described by Orr (2021). The refined list of management strategies was then distributed to the experts, who were asked to rate the importance of each strategy in ensuring food security on a scale of 1–5. Specifically, a rating of 1 indicated that the strategy was ‘very unimportant’, while a rating of 2 indicated that it was ‘slightly unimportant’, a rating of 3 indicated that it was ‘important’, and a rating of 4 indicated that it was ‘fairly important’. In addition to their ratings, the experts were provided with space to explain the reasons behind their ratings.

Third round of the Delphi study

After collecting and analysing data from the second round, management strategies with a mean importance score (MIS) below 4 out of 5 were excluded from further analysis. The refined list of strategies, along with their respective MIS and the expert’s own score for each strategy, was shared with the panellists to evaluate the validity of the retained strategies after the second round (Orr, 2021). Experts were also given the opportunity to adjust their scores based on the supplied mean scores if they wished to do so. Following the elimination threshold mentioned earlier, the list of management strategies was further refined, and the final set of management strategies was determined.

Results and discussion

Impacts of WrTs on the four pillars of food security in the ISD under climate change

From the reviewed studies, nine pathways affecting food availability were identified, as shown in Figure 4 (see Table S1 in the supplemental data online for details). The experts on the panel strongly agreed (100%) that cyclones, storm surges, floods and waterlogging cause yield loss at ISD. These water-related risks mainly occur during crop plantation or harvesting, damaging crops (Padhy et al., 2021). A high level of agreement was also found for the reduction in arable lands (83.33%) and decreased crop productivity due to the intrusion of saline water (71.43%). In various parts of the ISD, sea-level rise and coastal erosion have caused the loss of agricultural lands (Hajra et al., 2018). According to Mandal and Nayak (2022), from 1975 to 2015, the erosion rate in the ISD exceeded the accretion rate, resulting in the loss of around 14.30 km² of land. This has been further worsened by saline water intrusion and insufficient drainage facilities, which have converted cultivable land into marshy areas (Thakur et al., 2021). Consequently, areas such as Ghoramara, Dhablat, Iswaripur, Baliara, Gobardhanpur and Kumirmari have encountered a substantial reduction in crop productivity and loss of arable land (Mukherjee & Siddique, 2022).

Figure 4. Water-related threats and their impacts on the four pillars of food security (Food availability: AVAL1–AVAL9; Food access: ACCS1–ACCS4; Food utilization: UTIL1–UTIL4; and Food stability: STBL1–STBL2) under climate change in the Indian Sundarbans, and experts’ agreement (%) on these (the abbreviations are defined in the figure itself).

Strong waves during extreme weather events cause breaches in embankments around low-lying areas, leading to saline water intrusion in agricultural fields (Chaudhuri et al., 2021). The increase in soil salinity is impacting the physicochemical properties of the soil and reducing the productivity of rice, which is the staple food in the region (Ghosh et al., 2021). In some cases, the soil salinity has surpassed eight ppt, far beyond the threshold level suitable for paddy cultivation (6 ppt; Haldar & Debnath, 2014). Besides, the panellists also strongly agreed on yield loss owing to untimely and erratic rainfall (71.43%). The prolonged dry spells and sudden extreme rainfalls during the monsoon have increased the incidence of crop failure and, at the same time, an outbreak of crop pests and diseases such as plant hoppers, causing significant losses in rice yields (Debnath, 2017; Mandal et al., 2015).

The destruction of grain storage facilities due to the impacts associated with extreme climatic events such as cyclones, storms, rainfall, sea inundation and flooding also garnered a strong agreement among the panellists (71.43%). The strong winds associated with cyclonic storms often destroy the grain storage of rural people (Ghosh et al., 2018; Hajra et al., 2018). The loss of grain storage generates food shortages in the affected households and damages the seeds stored for future production, ultimately having a negative effect on food security (Jadav, 2020). Cyclones also wreck animal-rearing shelters and sweep away most of the cattle and domestic animals, posing a severe threat to the rural poor’s source of protein and other vital micronutrients (Sen & Prasad, 2020).

In addition to decreasing agriculture yield, climate change-induced WrTs have negatively impacted both inland and marine fish populations, creating an enormous threat to the protein intake of the locals (Dutta et al., 2020). Usually, storm surges tend to breach the earthen pond dykes, causing freshwater ponds to overflow and, at the same time, be filled with saline water (Dasgupta et al., 2020). The intrusion of saltwater during floods and surges disrupts freshwater ecosystems and causes high mortality rates in fish species that cannot adapt to sudden changes in salinity (Dubey et al., 2017). Salinity has also risen in rivers, streams and intertidal zones (Figure 5), diminishing fish populations that were formerly available abundantly and constituted an essential part of the local diet (Mukhopadhyay et al., 2018). The increased temperature and salinity levels are causing a decline in the reproductive success of specific vital local fish species (such as Mystus sp., Parambassis sp. and Ompok sp.), resulting in reduced population sizes, while simultaneously, the elevated sea surface temperature is compelling fish species to migrate to greater depths in the ocean, leading to a significant decrease in catches along coastal regions (Ghosh, 2018).

Figure 5. River water salinity (ppt) in different sites of the Indian Sundarbans, February–May 2019.

Source: https://datacatalog.worldbank.org/search/dataset/0038270

Impacts on access to food

The panellists strongly agree (71.43%) that the displacement of communities by extreme weather events results in challenges in accessing food (Figure 3). This often happens in the ISD due to cyclones, storms and flooding; during these events, people take shelter in schools and are given low-nutritional foods (such as puffed rice and a mixture of rice and lentils), leading to extreme food insecurity (Mukherjee & Siddique, 2018). In remote parts of the islands where infrastructure is lacking, cyclones leave many families without shelter or food, forcing them to stay on embankments (Ghosh, 2021). People who have lost their homes and land to the sea are also compelled to migrate, which makes it challenging to find new homes and income sources, thereby reducing access to food (Guha & Roy, 2016; Sahana et al., 2019).

Out of the panellists, 57.14% strongly agree, while 28.57% agree that the reduced profitability of conventional agro-fishing livelihoods is constraining food purchasing capacity in the ISD (Figure 3). These livelihood options are significantly threatened by climate change, leading to increased poverty among farmer communities (Thakur, 2020). Honey collection from mangroves, another source of income, faces challenges such as decreased honey production due to cyclones destroying honeycombs, changes in mangrove species composition, and the resulting changes in honey quality and texture, affecting its market demand (Mukhopadhyay et al., 2018; Samanta et al., 2021). The practice of sun-drying fish on seashores is also under threat because of land erosion and diminishing coastlines, depletion of fish populations, the devastation of drying facilities during severe cyclones, and unanticipated precipitation during drying periods, which all contribute to decreased earnings (Augustin, 2019; Bandyopadhyay et al., 2022).

The changes in traditional livelihood options have caused a significant impact on the purchasing power of households, leading them to opt for less nutritious food choices, as evidenced in the study by Ghosh et al. (2018). This phenomenon is exacerbated by the loss of locally grown crops due to floods and cyclones, resulting in a decrease in food production and a surge in food prices in local markets, limiting the food options for the locals (Bera, 2014; Mukherjee & Siddique, 2019). Gender inequality further worsens the situation, as women and children tend to receive a disproportionate share of food in households, leading to a higher incidence of macro- and micronutrient deficiencies (Karmakar, 2021). Cyclonic storms and floods lead to the destruction of thousands of houses each year, compelling residents to allocate additional funds for repairing their homes before the cyclone season begins, which often leads to a reduction in their food budget and, as a result, less nutritious diets and lower food availability (Bera, 2014; Ghosh, 2021). The storms in the ISD make a significant portion of the transport network unusable, resulting in disrupted food access during disasters, as agricultural trades and food aid distribution are hindered (Vadrevu & Kanjilal, 2016). The inadequate defence of unsealed roads against climatic adversities and halted transportation through waterways are two major factors contributing to this situation (Paul & Chatterjee, 2019).

Impacts on food utilization

The ISD experiences annual outbreaks of communicable waterborne diseases, resulting in high mortality rates, as confirmed by the panellists (Figure 4). According to a World Bank report, approximately 225 Sundarbans residents die annually from diarrhoea, and there are around 1.5 million cases among children under and above five years old (Sánchez-Triana et al., 2014). Floods in most areas persist above ankle height for months, submerging sanitary infrastructure and resulting in septic tanks overflowing and seeping into surface water, making people more vulnerable to these diseases (Paul & Chatterjee, 2019). The use of polluted saline water for cooking and the increased prevalence of microorganisms and toxins that negatively impact food safety, while the vertical transport of salinized surface water into underlying aquifers leads to groundwater salinization, lowering the quality of potable water supplies (Mukherjee & Siddique, 2018; Nath et al., 2021). The salinity in tube well water samples exceeded 1 ppt (Figure 6), especially in Gosaba, Hingalgunj and Patharpratima blocks, making it unsafe to consume (Dasgupta et al., 2020).

Figure 6. Average salinity of the tube well water in different sites of the Indian Sundarbans, February–May 2019.

Source: https://datacatalog.worldbank.org/search/dataset/0038270

During extreme weather events, water, sanitation and hygiene facilities are often inadequate in shelters, making life much more difficult, especially for vulnerable populations such as the elderly, pregnant women and differently abled persons who require constant care and assistance (Ghosh et al., 2018). Besides, mental health disorders have significantly increased after cyclone Aila in 2009, causing issues such as post-traumatic stress disorder and insomnia, which are ecopsychiatric problems deeply connected to climate change-related ecological imbalances in the ISD (Bera, 2014). The devastating consequences of intense cyclones, storm surges and floods, such as property destruction, community displacement and livelihood loss, lead to traumatic stress disorder, haunting memory flashbacks and a profound negative impact on mental health (Pramanik et al., 2022).

Moreover, the livelihood uncertainty and ecological changes in peripheral mangrove areas have pushed inhabitants to collect wood and non-timber forest products and face tiger attacks (Chowdhury et al., 2013). The ‘tiger widows’ (women who have lost their husbands to tiger attacks in the ISD) endure a variety of societal stigmas, psychological scars and deprivation, affecting their work participation as well as food intake (Chowdhury et al., 2016). Due to rising salinity, habitat loss and a decline in prey population, tiger incursions into human-inhabited areas and the incidence of death by tiger attacks have significantly increased in recent decades, stimulating stress levels among individuals and affecting their food intake (Sánchez-Triana et al., 2014). Eating disorders and nutritional deficiencies not only cause physical sickness and impair working capacity but there is emerging evidence that nutrient deficits can further intensify depression and other psychological disorders (Rao et al., 2008).

Impacts on food stability

The review indicates that an increase in frequency and intensity of extreme weather events (42.86% of the panellists strongly agreed and 42.86% agreed), as well as forced migration and conflicts (71.43% of the panellists strongly agreed and 14.29% agreed), are likely to disrupt the stability of food availability, access and utilization in the ISD. Several studies have indicated that climatic disasters would worsen over time in this region. For instance, Reddy et al. (2021) found that tropical cyclones over the Bay of Bengal are projected to become more intense. The study also predicted that very severe and extremely severe cyclonic storms would likely escalate to the next higher category level, resulting in a significant rise in damage potential in the ISD. PLN and Kolukula (2023) estimated that the storm surge heights and associated inundation extent would likely increase due to the increased tropical cyclone frequency and intensity in cyclonic tracks due to climate change. Consequently, this could lead to more saline water intrusion into farmlands, floods, waterlogging, lack of freshwater availability and, ultimately, disrupting food stability.

Moreover, due to the continuous rise in temperature and the resultant melting of ice, the sea-level rise in the ISD could be about 4 mm/year up to 2090 (Leijnse et al., 2021). The rising sea level, coupled with increasing salinity, is reducing the extent of mangrove forests and limiting the diversity of mangrove species in the ISD, thereby affecting ecosystem services and posing a threat to the livelihoods of many, especially those who rely on mangrove-dependent activities (Mukhopadhyay et al., 2018). These factors have also resulted in a substantial decline in blue carbon reserves (Samanta et al., 2021). The deterioration and depletion of these ecosystems are anticipated to endure and potentially amplify as sea levels rise, and it is estimated that mangrove loss will reach 22,286 ha between 2020 and 2050 (Jayanthi et al., 2023). In addition, the ISD would experience a high number of internal displacements and migration. According to Kulp and Strauss (2019), sea-level rise by 2050 would be sufficient to submerge a substantial portion of the landmass and uproot between 140 million and 170 million people, including in the ISD. These could result in a higher possibility of instability and disruption of food availability, ease of access and utilization.

Delphi study and identification of the most relevant management strategies and policy

After analysing the responses from the first round of the Delphi study, a list of 81 management strategies was created by combining similar ideas and removing duplicates (see Table S2 in the supplemental data online). However, eight strategies were dropped in the second round since they did not meet the four or higher MIS threshold criteria. As a result, the remaining 73 strategies were identified as the most crucial for addressing the impacts on the four pillars of food security. These 73 strategies had an MIS above 4 and persisted on the priority list even after the third round (see Table S3 online). Among these strategies, 35 were related to the availability dimension, 20 to access, 13 to utilization and five to the stability of food security. The top strategies that had an MIS score of 5 with 0 standard deviation (SD) are discussed in the following section, along with other prioritized strategies to ensure the four pillars of food security in the ISD.

Strategies enjoying a complete consensus among the panellists

Table 1 presents the findings of the Delphi study in which seven strategies were rated as ‘very important’ by all experts and scored 5. The strategies that received unanimous support in the second and third rounds of the study were constructing scientifically designed embankments, planting mangroves and restoring mangrove areas. These strategies can not only address the loss of arable land but also protect people’s lives and livelihoods from cyclones, storm surges and coastal flooding while restoring ecological balance (Mukhopadhyay et al., 2018; Padhy et al., 2021; Karsch et al., 2023). Building embankments is particularly urgent in the delta because traditional earthen embankments are fragile and prone to breaching, even when reconstructed (Chaudhuri et al., 2021; The Hindu, 2010).

Table 1. Strategies that attained the highest priority in the Delphi study.

Four pillars of food security	Management strategies	Results from the second round of Delphi		Results from the third round of Delphi
		MIS	SD	MIS	SD
Availability	Constructing scientifically designed embankments and plantation of mangroves on the periphery and outer slope of the embankments to protect areas from erosion resulting from storms, cyclones and tidal upsurges	5.00	0.00	5.00	0.00
	Restoring mangrove areas along the sea faces and estuary banks to help offset the impacts of sea-level rise	5.00	0.00	5.00	0.00
Access	Increasing the availability of food aid	4.86	0.35	4.86	0.35
	Increasing the number of cyclone shelters with adequate facilities	4.86	0.35	4.86	0.35
	Generating awareness about government schemes	4.86	0.35	4.86	0.35
	Improving water transport facilities	4.86	0.35	4.86	0.35
	Developing floating granaries for distribution of food during the uncertain conditions	4.86	0.35	4.86	0.35
Utilization	Repairing the existing non-functioning tube wells	5.00	0.00	5.00	0.00
	Educating people about the maintenance of hygiene	4.86	0.35	5.00	0.00
	Including more households in the Swajaldhara project	5.00	0.00	5.00	0.00
Stability	Continuous monitoring of tidal fluctuations, pH variations, and salinity to support the regeneration and colonization of suitable mangrove species for restoring ecosystem services	5.00	0.00	5.00	0.00
	Continuous coordination and communication between the government, non-government organizations, and other stakeholders with the inhabitants for building climate-resilient livelihoods	5.00	0.00	5.00	0.00

Note: MIS, mean importance score; SD, standard deviation.

Another set of strategies that received a rating of 5 with 0 SD involves improving access to safe drinking water and training people about maintaining good hygiene. These strategies are fundamental for preventing the spread of diseases and enhancing health, which in turn promotes better food utilization and increased capacity for productive activities. It is essential for individuals to understand the relationship between diseases and hygiene to improve their health, and campaigns aimed at raising awareness should emphasize the need for training on these links. In addition to these strategies, the study identified two others that received an MIS of 5, which are continuous monitoring of tidal fluctuations, pH variations and salinity levels to support the regeneration and colonization of suitable mangrove species for restoring ecosystem services, and continuous coordination and communication between different stakeholders, including inhabitants, for building climate-resilient livelihoods (Table 1). These strategies are crucial for maintaining the health and resilience of the Sundarbans’ fragile ecosystem and ensuring its ability to sustainably support the livelihoods of local communities. The second strategy would ensure community participation in creating and implementing sustainable strategies to effectively deal with the complex and interconnected impacts of climate change at ISD.

Prioritized strategies for enhancing food availability

To reduce the negative effects of increased saline water intrusion on crop production, panellists recommended two management strategies with higher MIS: categorizing agricultural land based on soil properties, planting suitable crops and adopting high-yield crop varieties that can tolerate saline water. Panellists mentioned that current saline water-tolerant cultivars have low yields and produce thick grains, which are difficult to market. Unsuitable high-yielding rice cultivars and chemical fertilizers exacerbate the problem, and a lack of soil property knowledge can lead to crop failure. Therefore, soil classification and adoption of appropriate salt-tolerant crops are crucial for enhancing crop production and profitability. To mitigate the impact of extreme weather events on crop yield losses, some panellists suggested that it is impossible to entirely prevent unpredictable natural disasters. Nevertheless, they also highlighted the importance of preventive measures such as embankment management, coastal afforestation to create green belts and windbreaks, and improving drainage systems to prevent water stagnation on farmlands since stagnant saltwater often degrades soil quality and reduces freshwater availability (see Table S3 in the supplemental data online).

Building community-level and all-weather storage facilities for seeds and agricultural harvests is also necessary to mitigate yield losses caused by untimely or erratic rains, as well as the destruction of grain storage facilities by extreme weather events. The panellists opined that insufficient storage facilities force farmers to sell their produce at a loss following cyclone announcements. Additionally, improving livestock shelters and poultry houses through modern technology to withstand heavy winds and floods is essential. Increasing freshwater availability for irrigation purposes, rainwater harvesting in large coastal reservoirs, and cleaning ponds and water bodies with safe-to-use chemicals are also important measures. The cultivation of salinity-tolerant strains with freshwater fishes and the preservation of seeds of sweetwater fishes and other endangered fish species in seed banks were the two most critical methods for boosting the fish population – a vital source of food and income (see Table S3 in the supplemental data online). Raising the height of pond dykes was given higher scores in order to stop the saltwater intrusion and fish escapees, but one panellist expressed concern and stated that soil is scarce and expensive in ISD and that the water level during a flood often rises to 5–9 feet. Therefore, it might be necessary to conduct further research to better understand the specific challenges and opportunities associated with aquaculture in the ISD and to identify more tailored solutions.

Prioritized strategies for improving access to food

To protect residents of the ISD from water-related risks and enhance their purchasing power for food, the panellists emphasized several strategies. These included supporting women through the Self Help Group (SHG) for alternative livelihoods, promoting alternative livelihoods for forest-dependent communities, establishing community-level fish processing units and market links, and increasing the 100 days of work (see Table S3 in the supplemental data online). These approaches would help households cope with climate-induced water-related risks. The panellists also stressed the need to generate awareness about government schemes and control food prices for marginal communities to minimize the effects of price rises and spikes on low-income consumers, especially after shocks such as cyclones, storm surges and flooding (see Table S3 online).

The panellists also recommended different measures for increasing food accessibility for the climate-driven temporarily displaced and permanently displaced households in the ISD. For the former, they suggested increasing the number of cyclone shelters with proper amenities and ensuring the availability of food aid. On the other hand, for the latter, the panellists emphasized the importance of securing comparable livelihood opportunities for the displaced communities and identifying climate refugees as a distinct group of displaced individuals to provide them with humanitarian justice (see Table S3 in the supplemental data online). Since climate change is advancing rapidly and leading to the displacement of people, global greenhouse gas emission reduction and the recognition of ‘climate refugees’ are critical for mitigating the effects of rising sea levels and displacement of people. Besides, to manage transportation infrastructure and food supply disruptions following cyclonic storms, the panellists suggested developing floating granaries for food distribution and improving water transport facilities (see Table S3 in the supplemental data online). These measures could involve improving the capacity of existing water transport systems or constructing new ones, as most of the islands in the ISD are interconnected with waterways.

Prioritized strategies for improving food utilization

The panellists opined that improving food utilization in the ISD requires a multifaceted approach that includes ensuring access to safe drinking water and sanitation facilities, providing immediate medical care to those in poor health, improving healthcare services, and raising awareness among individuals at risk of exposure (see Table S3 in the supplemental data online). To prevent water contamination and health hazards during floods, tube wells and toilets should be installed on elevated platforms so that the risk of contamination can be reduced as floodwater may not be able to reach them. Access to safe drinking water and sanitation facilities is essential to prevent water contamination and health hazards during floods in the Indian Sundarbans. The lack of safe drinking water and sanitation facilities can spread waterborne diseases, which can further exacerbate food insecurity by affecting people’s ability to utilize food efficiently. Besides, improving healthcare services and raising awareness among individuals at risk of exposure can help to maintain good health, which is essential for proper food utilization. Healthcare services can provide medical treatment and support for those affected by climate disasters, including nutritional support for those suffering from malnutrition. Raising awareness, on the other hand, among individuals at risk of exposure can help them to take preventive measures and reduce their risk of exposure to climate disasters. This can include information on how to prepare for disasters, what to do during and after disasters, and how to access healthcare services in case of emergency.

Prioritized strategies for maintaining food stability

For maintaining food stability, the panellists stressed creating location-specific baseline data for tracking the threats to physical and socio-politico-economic conditions to avoid disruption of food availability, accessibility and utilization (see Table S3 in the supplemental data online). The dynamic ecological, geographical and socio-politico-economic features can cause spatiotemporal variation in vulnerability and food insecurity. In this context, baseline data can provide policymakers with the necessary information to develop targeted interventions to address the specific challenges facing the region. Besides, the panellists also opined that it is important to provide legal channels for vulnerable populations to access their livelihood entitlements to ensure food stability. Proactive migration is better for the delta populations because it involves planned relocation before a natural disaster occurs rather than after the fact (Vinke et al., 2020). In delta regions such as the ISD, where climate change and sea-level rise are causing increased flooding and salinity intrusion, proactive migration can help reduce the risk of food insecurity caused by displacement and loss of livelihoods. Proactive migration could enable vulnerable populations to access livelihood entitlements and move to safer areas, reducing their exposure to health risks and increasing their chances of obtaining food and other basic necessities. This approach can also help ensure that adequate support and resources are in place to assist with the relocation and integration of migrants, reducing the potential for social conflict and economic instability.

Conclusions and policy recommendations

Climate change impacts water availability and management in various ways, posing challenges to ensuring food security. Due to its vulnerable socio-economic and ecological conditions and exposure to WrTs, the ISD has become a climate change hotspot. This study reviews grey and academic literature to identify WrTs in the ISD resulting from changing climatic conditions and their impact on the four pillars of food security. Through an expert knowledge-based Delphi study, this study also proposes management strategies to address these threats.

The findings reveal that climate change has disrupted monsoon precipitation patterns, caused sea-level rise, increased sea surface temperatures, extreme weather events, storm surges, flooding, erosion, embankment breaching, land subsidence, waterlogging, salinization and other challenges in the ISD. These factors impact agricultural production, storage and supply, reducing food availability. Rural households face difficulty accessing sufficient and high-quality food due to decreased income from traditional agro-fishing livelihoods caused by water-related risks. Extreme climatic events and rising food prices have further reduced access to food. The quality of drinking water has deteriorated, compromising nutrient absorption and causing a negative impact on health conditions through the spread of waterborne diseases. Further, climate change-induced mental health disorders at ISD indirectly or directly affect work participation, impacting food intake and utilization. It is expected that there will be a rise in the frequency and intensity of extreme weather events in the future, which will have a further impact on the stability of food supply, access and utilization in the ISD.

The recommendations put forth by the panellists, who participated in the Delphi study, suggest that restoring the ecological balance of the ISD through mangrove plantations and constructing scientifically designed embankments would greatly benefit the four pillars of food security. Additionally, efforts to improve access to potable water, including fixing non-functioning tube wells and expanding clean water projects, would enhance the utilization dimension of food security in the ISD. Programmes aimed at promoting good hygiene practices and continuous monitoring of the changing physical environment in the ISD to support mangrove regeneration and colonization would further aid in maintaining the stability dimension in the face of climate change impacts. The strategies proposed to align with several Sustainable Development Goals (SDGs), including SDGs 1 (No Poverty), 2 (Zero Hunger), 3 (Good Health and Well-being), 6 (Clean Water and Sanitation) and 13 (Climate Action). However, this study has primarily focused on WrTs under climate change; there may be other pathways through which food security in the ISD could be compromised. Additionally, the effects on individuals who rely on ISD produce were not investigated. Due to the study’s larger scale, more attention is needed to conduct micro-level empirical research involving various stakeholders to add location-specific insights to the findings and advance the research domain.

Acknowledgements

The authors express their gratitude for the invaluable feedback and suggestions provided by the journal’s editor-in-chief, the anonymous reviewers, as well as the organizers, discussant and participants of the conference entitled Water Resource Management for Achieving Food Security in Asia Under Climate Change, 26–27 October 2022. Furthermore, the authors convey their deep appreciation to the Asian Development Bank Institute (ADBI) and the guest editors for initiating this special issue. The authors also acknowledge the assistance of Dr Panharoth Chhay (Research Associate, ADBI) during the manuscript submission process. Besides, they are thankful to the experts who participated in the Delphi study and generously shared their valuable knowledge.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed at https://doi.org/10.1080/07900627.2023.2224459