1 Introduction

Water management system is very complex in the coastal Bangladesh. Water also supports all forms of lives [1] including human and commonly used in several sectors, i.e., agricultural cultivation, industrial raw material, [2, 3] household chores and recreational use. Total almost 71% earth’s surface covered with water of which 2.53% is fresh water. About 0.26% of all fresh water is available to human consumption and it is stored in streams, lakes, soil moisture and groundwater [4]. Rest of the water is unreachable to use because it is stored in forms of glacier in different parts of the world [1]. Global fresh water demand is increasing to escalation by 55% in upcoming few decades [5]. Fresh water crisis and decelerating water quality are major issues and challenges in the current world. It turned into a crucial problem in the Asian countries of the world [6, 7]. This crisis is further increased due to unexpected changing of rainfall and different climatic hazards. UN [8] reported that global water demand has growing more than twice than the population increasing rate. This scenario has been observed in agricultural based developing countries like Bangladesh [9]. Many coastal region of the world are visible to noteworthy fresh water crisis and have susceptible to more vulnerable owing to natural and manmade calamities [10]. About 3.6 billion people faced water crisis since 2018 and 35 million global coastal people are challenged with availability of continuous fresh water supply due to salinity disturbance and pollution [2, 11, 12]. World Bank [13] claimed that internal migration (within the countries) was increased by 10% between 1970 and 2000 due to shortage of fresh water.

Groundwater is very important to face water scarcity and it is used for different purposes [14] and surface water is not pollution free in the coastal Bangladesh due to different pollutants. People are sufferings from arsenic contamination as well as frequent disasters [3], salinity intrusion, potable jar water contamination [15], groundwater contamination [16] and pollution with heavy metals [17]. Saline water increased the possibility of skin, heart and kidney diseases as well as other respiratory diseases in the coastal area compared to other area of the country [18]. About 50 million coastal respondents are susceptible to groundwater arsenic pollutions in Bangladesh [19]. People are highly dependent on groundwater in the dry or winter season because of limited supply of unimproved water [20] mainly pond water for drinking or non-drinking purposes [2]. The shallow aquifers (within 90 m) of coastal Bangladesh are polluted with several physical and chemical properties and surface water is not available in winter season [21]; as well as deep/shallow tube wells do not functionally active in the certain coastal districts of Bangladesh due to arsenic and salinity [3], so, pond sand filter (PSF) is the alternative options to meet the demands of water crisis [22]. Almost all the people of the coastal area received this technology for safe drinking water. About 95% respondents claimed that one PSF could solve fresh water demand of minimum 50 households [23]. Abedin [3] reported that Department of Public Health and Engineering (DPHE) is responsible for supplying fresh water at national level of Bangladesh. Along with DPHE, some NGOs (UNICEF, UNDP and World Bank) have been taken small scale projects for implementing improved pipe water supply system in the selected coastal areas of Bangladesh [21] and also other available household level adaptive measures [24] (rainwater harvesting, use of PSF water). The individuals contributed priority to water management by several types of activities such as, cash supply, labor, materials or pumping the hand-held tube well attached in PSF. There are some committees to monitor the functional activities of protected pond, PSF or other sources of fresh water. These committee have the responsibility for repairing and maintenance the current water sources to functionally active it round the year.

There were various studies done by different scientist directly connecting with this topic. Ahsan [2] claimed about assessment of domestic adaptation strategies to water stress in southwestern coastal parts of the country. Abedin [25] reported on climate change, water scarcity and health adaptation in this area also. Tashmin [26] reported on challenges of regional coping capabilities due to climate change in the coastal areas of Bangladesh. Abedin [3] argued about community opinions and adaptation to fresh drinking water shortage regarding salinity, arsenic and drought risks in coastal areas of Bangladesh. Azam and Sarker [27] argued the adaptation strategies for fresh drinking water supply in coastal Bangladesh. Abedin [28] claimed about the impacts of salinity, arsenic and drought in our study area. But best of our knowledge, we didn’t find any comparative study among shoreline, interim and inland coastal areas fresh water management connected with preparedness and adaptation. Thus, the researchers have been selected this topic to conduct the study. The objectives of this research were to investigate the (i) current fresh water management with preparedness and adaptation strategies (ii) challenges to implement suitable adaptive measures in the coastal areas of Bangladesh.

2 Framework of preparedness and adaptation

Bangladesh is dominantly using the groundwater from tube well for its all sectoral use. But, it should not functionally active round the year because it is fully depended upon the recharge from surface water either rainfall or river water which is prone to reduce in recent years. Some initiatives may smooth water supply round the year, i.e., conserve the rainwater for long time in drum or ferro cement tank, use of surface water for household chores, etc. Use of surface water for poultry/animal rearing and households washing that may reduce the fresh water demand. In this study, preparedness consisted of conservation practices of drinking and rainwater, household and homestead agricultural preparedness, contributions in water management, responsibility and efficacy of the committee, water point repairing and break down period and satisfaction level of current water supply system.

Adaptation should significantly reduce the risk/vulnerability of fresh water management in winter season. This may perform better when local stakeholders are worked together [25, 29]. Adaptation decreases vulnerability but rises resilience; well developed and equipped strategies give the maximum precedence to the split ends of the local respondents with appreciating their facts and knowledge. Adaptive measures should be taken by considering the fresh water scarcity, seasonal fluctuation, water supply and distribution system, economic capacity and the impacts on human health. But urgent to know the intensity of water problem and tentative solutions for implementing the adaptive measures [25]. Adaptive measures are taken by individually and institutionally based on the villagers needs and demands. Some adaptation strategies are indigenous and assimilated from surrounding coastal regions of Bangladesh. This research also includes the challenges to implement the adaptive measures.

3 Materials and methods

3.1 Study area

Six coastal districts (Satkhira, Khulna, Bagerhat, Pirojpur, Barguna and Patuakhali) were recognized as southwestern coastal area that exist acute crisis of fresh water. The socio-economic status, occupation, sources of fresh water, livelihood strategies of this area are almost same. Thus, among these six districts, the adjacent three districts, Satkhira, Khulna and Bagerhat were purposively designated to perform the study. Sarankhola, Batiaghata and Kalaroa Upazila were also purposively selected and named as shoreline, interim and inland area (Fig. 1). The Upazila Sarankhola was the adjacent area of world largest mangrove forest ‘The Sundarbans’ and extreme climatic threats, highly disaster prone, locked with polders, extreme salinity, erratic rainfall, river bank erosion, severe fresh water crisis in the winter season, unable to install deep tube well as well as exposed to the Bay of Bengal. Gangarampur village of Batiaghata Upazila was also moderate level salinity locked with polders, severe fresh water crisis in the winter and pre-monsoon season and about 21 km away from the city Khulna and unable to install deep tube well. The Upazila Kalaroa was located in the nearby of Jashore District and very far from the coastline as well as Bay of Bengal with low salinity but excessive arsenic concentration in groundwater and sono arsenic filter is the common source of fresh water. Unions and villages were also selected purposively depending upon fresh water crisis. BBS [30] reported that about 85.66% national households used tube well water as a source of drinking whereas 86.53% households from Khulna Division used same sources of water, followed by 11.74% (national) and 3.38% (Khulna) from pipe water; 0.59% (national) and 3.14% (Khulna) from potable jar water; 0.89% (national) and 3.76% (Khulna) from river/canal water; 0.42% (national) and 3.02% (Khulna) from rainwater.

Fig. 1
figure 1

Map of the study area identifying shoreline, interim and inland village

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3.2 Samplings and data collection

A total of 2789 households list were collected from the respective union parisad. Among them, total 338 households were determined by using Eq. (1) at 95% significance level which were proportionately distributed (Eq. 2) in three villages (Table 1). Respondents were selected based on simple random sampling without replacements from the collected household lists. Note that 15% reserve samples (Eq. 3) were also taken into consideration in case of absent or migrated households. The household head (HH) was the main respondents of the study but in case of absence of the HH, the spouse was the respondent. The age of the household ranged between 25 and 72 years. A self-developed and semi-structured face to face questionnaire survey were conducted from May–August 2022. The researcher went to the respondents’ house and proposed him/her about the willingness of the participation to our survey. After receiving verbal consent from the respondent, the questionnaire was filled in and ensured the confidentiality of the data provided by the respondent.

$$\mathrm{Total\, sample\, size},{\text{n}}=\frac{{{\text{z}}}^{2}.{\text{p}}.{\text{q}}.{\text{N}}}{{{\text{e}}}^{2} \left({\text{N}}-1\right)+{{\text{z}}}^{2}.{\text{p}}.{\text{q}}}$$
(1)
$$\mathrm{The\, sample\, size\, of\, each\, village}, {n}_{i}=\frac{{n}_{1}}{N}*n$$
(2)
$$\mathrm{and\, the\, reserve\, sample},\mathrm{ Sr }=\mathrm{ n}*\frac{15}{100}$$
(3)

where, N = known total population = (1518 + 581 + 690) = 2789, z = 1.96 (as per the normal curve for the given confidence interval at 95%), e = error limit at 5% (0.05), p = 0.5 (the estimated population proportion that maximize the sample size), q = (1-p) = 0.5.

Table 1 Sampling structure of the study
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Three FGDs from three selected villages (FGD 1, shoreline; FGD 2, interim; FGD 3, inland) with 12–14 individuals from each to understand the perception or opinions collectively and also validate the collected questionnaire data that accelerate the access to fresh water and perceived the understanding of preparedness and adaptation strategies. An FGD continued 60–70 min with a pre-arranged checklist and noted the summary of the information with a recorder and a moderator. The details were depicted in Tables 2 and and available sources of water were tabulated in Table 3.

Table 2 Research purposes, methods and target population
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Table 3 Available water sources in the study area
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3.3 Data processing and analysis

After collecting data, it was verified, reviewed, scrutinized and edited thoroughly to avoid errors and inconsistencies and coded for inserting into SPSS (version 22.0). Then, the data were analyzed to formulate frequency table, chi-square test, weighted average index (WAI) and radar diagram carefully. Study area map was drawn by Arc GIS (version 10.3) software.

3.4 Index formulation

Household and homestead agricultural level preparedness was measured by arithmetic weighted average index (WAI) formula given by Paul [31]/ Khan and Paul [32] stated in Eq. (4). This WAI was formulated from the pre-selected seven parameters collected by five-point Likert scale, 0 (indicating no preparedness) to 1 (highest preparedness) and the index was assessed into poor (< 0.33), moderate (0.33–0.66) and high (> 0.66) category.

$${\text{WAI }} = \, \left\{ {{\text{fNP}}*\left( 0 \right) \, + {\text{ fN}}*\left( {0.{25}} \right) \, + {\text{ fMP}}*\left( {0.{5}} \right) \, + {\text{ fSP}}*\left( {0.{75}} \right) \, + {\text{ fVSP}}*\left( {{1}.0} \right)} \right\}/{\text{N}}$$
(4)

Here, f (NP) = Frequency of no preparedness; f (N) = Frequency of neutral/depend on others preparedness; f (MP) = Frequency of moderate preparedness; f (SP) = Frequency of strong preparedness; f (VSP) = Frequency of very strong preparedness; N = Total observations (184, 73 and 84 for shoreline, interim and inland area).

4 Results

4.1 Conservation practices of drinking water and rainwater

In Bangladesh, the conservation practices of drinking water mainly dominated by plastic bottle or plastic drum or container. The study revealed that overall about 58% respondent used plastic bottle to conserve the drinking water, followed by plastic large drum/container (28%), silver pot (7%) and earthen container (5%) respectively. This result showed the increasing trend for plastic bottle from inland (49%) to shoreline (63%) area and decreasing trend for earthen container from inland (7%) to shoreline (4%) area. In addition, the study reported that about 35, 28 and 22% respondents from interim, shoreline and inland area used plastic large container to conserve drinking water. About 20% respondents from inland area used silver pot for drinking water conservation which was learnt from their parents and this trend was reduced from inland to shoreline area. The chi-square result showed significant difference among three study areas of coastal Bangladesh (Table 4).

Table 4 Conservation practices of drinking water
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The individuals of the study area collected rainwater in the rainy season and some families conserved this rainwater for long time (more than four months) in the plastic drum or container. Overall about 44% respondents conserved the rainwater in the plastic bottle (available from one-time water/oil bottle in the local market), followed by plastic drum (32%), silver pot (19%), earthen container (3%) respectively. About 50.54% respondents of shoreline area used plastic bottle, followed by interim (36.62%) and inland (36.14) respectively. The use of plastic drum was higher (46%) in the interim area, followed by shoreline (33%) and inland (19%) area respectively. Silver pots was also used (42%) to conserve the rainwater in the inland area, followed by shoreline (12%) and interim (9%) respectively. Ferro cement concrete container was available (about 1.63%) in the shoreline that was installed by NGOs after category four cyclone Sidr (struck in the south western coastal Bangladesh in 2007 with up to 240 km wind speeds). The chi-square test showed significant difference among three shoreline, interim and inland zones of Bangladesh (Table 4).

4.2 Household and homestead agricultural preparedness

The study resulted the household and homestead agricultural preparedness for seven different variables for three coastal area of Bangladesh. This radar diagram (Fig. 2) was formulated based on the respondent’s perception collected through questionnaire survey. The strength of the house indicated the economic status and financial solvency of the household if this household was constructed by the respondent’s self-financing. The study claimed that the strength of the house was better in the inland (0.702) than that of shoreline (0.682) and interim (0.552) area. The preparedness level for homestead irrigation in winter season was better in interim (0.458) than that of shoreline (0.364) and inland (0.244) area. The conservation of pond water for irrigation was better in the shoreline (0.372) than that of interim (0.245) and inland (0.112) area. Highest index observed for buying water pump for irrigation in the interim area (0.232) than inland (0.099) and shoreline (0.077) area. The main possible reason of that the respondents of this area installed shallow tube wells in the agricultural field and used water pump for the irrigation system of watermelon. The overall conservation of rainwater for drinking purposes was better in the inland (0.542) than interim (0.324) and shoreline (0.288) area. In addition, the capacity of buying large water container (plastic) was also better in the inland (0.341) than that of shoreline (0.151) and interim (0.162) area (Fig. 2). The mean WAI of this preparedness level was claimed as moderate (0.332) in the inland area and poor in the shoreline (0.313) and interim (0.309) area respectively.

Fig. 2
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Radar diagram of WAI of household and homestead agricultural preparedness

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4.3 Types of contribution in water management

The study claimed that about 66.85, 54.93 and 73.49% respondents participated by different ways individually from shoreline, interim and inland study area respectively. Rest of the respondents were only receiving benefit from the water sources but disagree to contribute in any ways. Among them, overall 42% respondents worked as a labor to repair or clean the PSF or the sources of water, followed by 30% supported by cash, 17% supported by materials or repairing components in the study area. Meanwhile, 48, 66 and 13% respondents from shoreline, interim and inland area worked as labor to reconstruct or repairing their water sources. Likewise, 34, 25 and 26% respondents from shoreline, interim and inland area contributed by cash during repairing or reconstructing their water sources (Table 5). FGD 1 and FGD 2 reported that water management committee can not sincere about their duties and responsibilities properly. For this reason, all households do not contribute in the water management when requires this type of assistance.

Table 5 Individual contribution to water management
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4.4 Existing committees for taking responsibility and efficacy of the committee

Department of Public Health Engineering (DPHE) and local NGOs selected the sites for setting up PSF based on the two major criteria (fresh water crisis and the accessibility of the pond water) but they (DPHE) could not take the responsibility for post-operative maintenance and operational activities. The beneficiary local people were responsible for it. Ansari and Roy [23] proposed a maintenance committee encompassing 5–8 peoples plus two women. Hossain [33] reported about 75% PSFs are abandoned after 18 months from establishment. Hutchings [34] proposed a community management plus model for solving these issues but other researchers [35,36,37] named it as (in)direct or post operational support. The study reported that about 32, 38 and 30% (overall 32.84%) respondents from shoreline, interim and inland area declared that there is PSF management committee for repairing and maintenance. This result was consistent with Ansari and Roy [23] that declared about 78.98% replied positive answer regarding PSF management committee study conducted in Shyamnagar Upazila, Satkhira. Local people are nominated committee members through a general meeting [38]. The study found that about 29, 38 and 26% (overall 30%) respondents from shoreline, interim and inland areas replied these committee carried their duties effectively and satisfied all the villagers. This result was also consistent with Ansari and Roy [23] reported it as 91%. A staff is allocated by the committee for each PSF but proper training should be ensured to handle the practical problem when required. This point was raised from FGD 1 that without training this committee should not always play proper role to solve the problem in the shoreline area. For this reason, some PSFs were not repaired for long time and after a certain period, this source of water was declared as abandoned. This FGD also claimed that it would be ensured that the pond was free from washing cloth by using detergent/soap or other chemicals, pisciculture for the degradation and deterioration of water quality. This was not always followed strictly by the management committee. The role of the management committee was not satisfactory in this connection [23] and it was supported by both FGD 1 and 2.

4.5 Water point break down and repairing period

The water point (specially PSF and sono filter) is very much affected by various natural calamities in the study area. The shoreline and interim area are affected by flood, cyclone, storm surges, salinity intrusion, etc. and the inland area is affected by drought, arsenic contamination, etc. The study claimed that overall about 57.99% respondents reported that the sources were broken down frequently in the last 5 years. In which, about 55.98, 49.30 and 69.88% claimed in the favor of this opinion from shoreline, interim and inland areas respectively. Some sources were broken down weekly (poor quality of PSF and sono filter), monthly (which are used by more than 50 households), quarterly (institutional sources) and yearly. Overall about 7, 46, 24 and 22% respondents argued that their water sources were broken down on weekly, monthly, quarterly and yearly basis. Highest 52% respondents from interim area claimed that their water sources were broken down monthly, followed by 49% (inland) and 42% (shoreline). The study also reported that about 19.57, 30.99 and 22.89% respondents from these areas were claimed that their water sources were broken down yearly (Table 6). This was supposed that these water sources were not properly repaired. It also reported that proper actions should not be taken during operation and maintenance. The chi-square result presented the significance difference among the study areas.

Table 6 Frequency of water point break down
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As all of the study coastal regions of Bangladesh has the example of water point breakdown for various reasons, these breakdown point has been repaired by individuals/management committee/local NGOs for several intervals. The study revealed that overall about 32.54% respondents reported the breakdown points were repaired within 7–15 days, followed by 16–30 days (21.60%), within 7 days (14.79%), 31–60 days (9.76%), 61–120 days (11.24%), > 120 days (10.06%) respectively. In addition, about 47.28, 11.27 and 18.07% respondents from shoreline, interim and inland area claimed that their water points were repaired by 7–15 days after break down (Table 7). It was also supported by FGD 1 and FGD 3 that some points were not repaired totally which had expired its duration at least 15 years and declared abandoned by the concerned authority with the help of management committee. Another point noted that overall about 45.86% respondents paid money during their repairing of PSF which was claimed by shoreline (48%), interim (25%) and inland (56%) areas respectively.

Table 7 Water point repairing after break down
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4.6 Satisfaction level of current water supply system

The study performed the perception of satisfaction level of the respondents regarding current water supply system. About 28.80, 19.72 and 21.69% respondents from shoreline, interim and inland area reported that they were satisfied with current water supply system. Majority of the respondents, 64.67, 74.65 and 61.45% from shoreline, interim and inland areas were not satisfied with current water supply system. The major causes of their dissatisfaction of the water supply system may be unavailability of fresh water in the crisis period, especially in the pre monsoon or winter season. The study claimed that overall about 25.15% respondents were satisfied with the current water supply system.

5 Adaptation strategies

Adaptation strategies were taken to reduce the fresh water crisis round the year in the coastal area of Bangladesh. It should be taken collectively by the respondents or institutionally to minimize the risk of vulnerability regarding fresh water management crisis in the study area.

5.1 Individual adaptation strategies

The individual adaptation strategies were taken by individual household to meet their water crisis. Three villagers were asked to opt their strategies individually during winter and rainy seasons. In this research, the researchers considered the winter and rainy season as the month between November-June and July–October respectively because the severe crisis occurred in the winter season. The study argued that overall about 89.94% respondents recommended rainwater harvesting as the most suitable options in the rainy season for meeting safe drinking water, followed by use of PSF water (20.71%), 20/30 L bottle water (14.79%), conservation of pond water (10.95%) respectively. These 20/30 L bottle water was supplied by local businessman that was locally treated by supplier or collected from nearby deep tube well (another village) which was purchased by the households. This water may help to avert from different water borne diseases (typhoid, cholera, diarrhea, etc.) and seems to be safe option for drinking water. A few people (about 5.03%) collected fresh water from far away (3-5km) in the rainy season because of inundation of nearby water source and rainwater is not collected by these group of people because they have no access to collect rainwater. About 1.48% respondent used pond water after boiling even in the rainy season. About 98.37, 83.10 and 77.11% respondents from shoreline, interim and inland area favored their opinion that rainwater harvesting was the main option for fresh drinking water, followed by use of PSF water, 11.41% (shoreline), 8.45% (interim) and 51.81% (inland) areas. From these results, it was reported that highest (51.81%) respondents from inland area used PSF water as drinking because of available pond water in the rainy season (Table 8). These results are almost consistent with Abedin [25] claimed that about 93% respondents used rainwater which is conducted in September–October, 2017 in Satkhira District.

Table 8 Individual adaptation strategies with seasonal variation
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But the opposite scenario observed in the winter season at all the study area. In winter, overall PSF was the dominant source of drinking water and other household chores (48.52%), followed by use of 20/30 L bottle water (27.81%), conservation of pond water (26.92%), collect water from 3 to 5 km away (25.44%), digging/re-excavation of pond (22.49%), boiling pond water (14.50%), boiling canal water (11.83%), use the harvested (ferro cement tank) rainwater (8.88%), installing deep tube well (5.92%, especially in inland area), installing tube well with overhead tank in inland area (1.78%) respectively. Highest about 65.76% respondents adopted the PSF technology from shoreline area, followed by 16.90% (interim) and 37.35% (inland area) respectively (Table 8). This result is consistent with Abedin [25] that about 85% respondent used PSF technology in another shoreline area of Satkhira District.

5.2 Institutional adaptation strategies

Institutions played a foremost performance in supplying and access to provide drinking water. Numerous government institutions, i.e., DPHE and various types of national and international NGOs, i.e., USAID, Action Aid, UNICEF, Sushilion, Uttaran, etc. were played very significant role to supply nonstop fresh water in the coastal Bangladesh [3]. DPHE is responsible for the establishment of PSF over the entire coastal belt of Bangladesh. Besides, some primary school, high school, mosque, temple or other social organization have played important role to meet the fresh water demand in the study area. These institutions conserved the pond water, set up deep tube well with overhead tank, rainwater harvesting, re-excavation the pond, proper management of PSF installed in their pond, etc. The respondents were reported different types of adaptation strategies supported by various institutions in the study area. The survey resulted that overall about 34.32% (winter) and 45.86% (rainy) respondents claimed about positive perception regarding the significant role of institution level for taking several adaptation strategies. Among them, in the rainy season, overall about 17.16% respondents reported that institution adopted rainwater harvesting in the study area; of which about 15.22, 15.49 and 22.89% respondents from shoreline, interim and inland village argued that institutions adopted this adaptation measures, followed by overall about 13.31% claimed that institution adopted PSF technology in the study area; of which about 14.13, 2.82 and 20.48% from shoreline, interim and inland area reported that institution adopted this technology (Table 9).

Table 9 Institution level adaptation strategies with seasonal variation
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In the winter season, re-excavation of ponds was another adaptation strategy in the coastal areas where drinking water insufficiency exists more rather than the rainy season because of drought and reducing the ground water level as well as river water. But the percentage of the respondents was very limited depending upon the demand of re-excavation of ponds. The study reported that overall about 34.32% respondents claimed that institution played significant role in the winter season to cope with different adaptation measures. Among them, about 9.24% respondents adopted with PSF water in shoreline area, followed by re-excavation of ponds (6.52%), 19.28% in inland area respectively (Table 9). In the interim area, a solar operated PSF implemented by an NGO, community development center (CODEC) with the financial help of climate smart village piloting program with coordination by an international NGO, Oxfam in 2020 in Gangarampur village in Batiaghata of Khulna District. FGD 3 reported that inland area is highly arsenic prone and institutions played significant role to identify and mark up arsenic contaminated tube wells [3, 28]. DPHE carried out this mark up by testing the arsenic concentration through a kit between 2020 and 2022. A tube well is mark up as red when the arsenic concentration exceeds the tolerance limit (0.05ppm) and within the tolerance limit mark up as green which is safe for drinking. It is found that almost 100% tube wells in the inland area are marked up with red. Thus, sono arsenic filter is the common adaptive strategies which is installed with overhead tank in this area.

5.3 Challenges to implement suitable adaptive strategies

Though different adaptive strategies are experienced in the coastal area of Bangladesh in the rainy season; the supreme task is to conserve rainwater for longer time, even some ferro cement tank existed in the shoreline area and 2000/3000 L plastic tank supplied by DPHE in all the study area but limited in number is the prime challenge for the respondents. Another challenge was that water tanks required regular and effective maintenance to avoid contamination and ensured the water quality. Generally, it is advised to turn on the tap for the first 5–6 min to flush the rainwater by which disposing the pollutants but it should not be possible always. The tanks need to be filled with rainwater immediate before the dry season and this water is to be used for next four/five months but it should not be followed always. Another adaptive option is the PSF water technology which is common in the shoreline and interim area but it should become a big challenge that the pond should be free from pisciculture and protected from using soap for bathing, washing clothes with detergent, watering livestock and other household activities. Sometimes, ponds are active with these activities should easily contaminated with different pathogens and microbial organisms as well as deteriorated the chemical properties of water which is not always treated by PSFs. As about BDT. 66,000 is required for the construction of a PSF for 60 households, this is another challenge for establishment of PSF [24]. On the other hand, collection of rainwater is totally depending upon the time and distribution of rainfall as well as duration of rainfall which varies from season to season and location to location in the coastal area of the country [25]. Annual rainfall in the southwestern part of the country is around 1612, 1423 and 1255mm in Bagerhat, Khulna and Satkhira District in the year of 2018 [39]. Most of the rainfall exists in 3–4 months (July–October) of the year and rest 8 months, the respondents have to conserve rainwater to plastic or earthen jars. But without maintaining proper system, it is very difficult to conserve rainwater for the long time and it should be possibility to contaminate with various types of bacteria, insects or other pathogens which might be cause of several water borne diseases. Thus, main weakness of rainwater harvesting is the possibility of microbial contamination and higher cost of storage in the study area for rest 8 months of the year. Moreover, establishment cost is not economic friendly for all the households in the study area. Apart from these two adaptive measures, use of 20/30 L bottle water is totally depended upon the economic capability of the householders. This potable water comes from deep tube well (another nearby village) or commercially purified with modern filtration systems and so on, with the support of international or national NGOs at the cost of TK. 0.40 per liter [25]. In addition, limited respondents are using this option because the available of the economic feasibility of the households. The communication system and available transport facilities are another barrier to collect fresh water in when the sources of water is far away from their houses. So, based on the research and FGDs opinion it is recommended that PSF technology (shoreline), pipeline water supply (interim) and sono arsenic filter (inland) will be the effective and suitable strategies in the study area to scale up and promote the policy makers for ensuring continuous fresh water supply round the year.

6 Conclusion

Preparedness and adaptive strategies should reduce the vulnerability of fresh water crisis that have taken by either individual or institution level. The respondents were adapted with several strategies during drought (inland) and acute crisis period (shoreline). These were rainwater harvesting, conserving pond water, use of PSF water, collect water from far away, etc. Though several adaptation strategies were taken but still it was appearing not to be sufficient to combat the existing fresh water crisis. More rapid supports were required to ensure nonstop supply of fresh water round the year. The adaptive capacity accelerates the institutional capacity building and access to climate resilience system of fresh water. Adaptation strategies (with combination of all other strategies) will be more effective in the short, medium and long-term planning including working with local communities and societies among the villagers for mutual understanding, learning knowledge from neighboring villages. The research concluded that villagers should come forward for ensuring nonstop fresh water accessibility round the year. Coastal population will be more conscious about wasting fresh water, pricing the water and improving the management strategies in the study area. The limitations of this research that community-based preparedness and adaptation strategies are not incorporating. A few respondents used modern technology (reverse osmosis system for purification water) who are excluded from this research. Agricultural water management and distribution system are out of the scope also. Further study should be done incorporating the industrial, agricultural and recreational water management and distribution system in the coastal area of Bangladesh for better results. As this study performed only in the south western coastal area; so, management system of other coastal area may differ from this result and further study can be accomplished in the central and south eastern areas of coastal Bangladesh.