Introduction

The Philippines has about 421 principal rivers (Scott 1989) and several studies had been conducted highlighting the importance of these rivers in terms of economic (Choe et al., 1996; Dusaran et al., 2010; Gorme et al., 2010) and biological perspectives (Alcala et al. 2010; Opiso et al., 2014; Malabrigo et al. 2014). However, rivers had been noted to be one of the contributors of plastic waste in the oceans (Leberton et al. 2017; van Emmerik et al. 2022). In fact, seven of the top ten rivers that mostly contribute to plastic waste discharges in the world’s oceans are situated in the Philippines (Ritchie, 2021). Poor solid waste management and improper waste disposal, particularly in rivers are one of the leading causes of plastic and water pollution (Ferronatto and Torretta, 2019; Lestari and Trihadiningrum, 2019; Escañan and Bacosa, 2022). The unregulated disposal of plastic waste in rivers can contribute to the degradation of aquatic ecosystems (Abreo et al., 2016; Abreo et al., 2019; Pacilan and Bacosa, 2022), and threats to public health (Maquart et al., 2022). Rivers are vital sources of freshwater and habitats for various species and provide essential services to communities (van der Ploeg et al., 2017). Therefore, there is a need to address the issue of solid waste management and promote pro-environmental behaviors among residents living along rivers for its conservation and protection (Hoffmann and Muttarak, 2020).

Residents living along rivers have a critical role in the conservation and protection of rivers through the implementation of pro-environmental behaviors (Srinivas, 2016). The daily activities of these residents such as proper plastic waste disposal, reduced use of single-use plastics, and responsible consumption may have a significant impact on the health of the rivers (Diola et al., 2020). Thus, understanding the factors affecting the intentions of residents living along rivers to implement pro-environmental behaviors are important in formulating effective strategies to promote and ensure the sustainable conservation of rivers (Zhong et al., 2019).

Cotabato City, situated on Mindanao Island, is geographically positioned between the Rio Grande de Mindanao and the Tamontaka Rivers. This strategic location renders it susceptible to the accumulation of floodwater from the neighboring Ligawasan marshland in Maguindanao del Norte, as documented in the “Philippines: master plan: report from 2013. The Esteros, Tamontaka, Matampay, and Rio Grande de Mindanao Rivers represent a subset of numerous rivers that traverse Cotabato City and ultimately discharge into Ilana Bay. These rivers provided economic and biodiversity services to the people residing near the area (Corcoro et al., 2012). The study of Corcoro et al. (2012), pointed out that these rivers are very important to residents aboding along the Cotabato City rivers. The majority of these residents used these rivers for laundry purposes, bathing, and for drinking. However, Rio Grande de Mindanao River has been noted to be one of the top ten transporters of plastic waste in the world’s oceans (Ritchie, 2021). This indicates that areas where this river traverses may have poor local waste management practices.  Thus, improving waste management and promoting pro-environmental behaviors are essential to avoid further degradation of the rivers (Janmaimool, 2017).

Several studies had been noted a positive correlation between pro-environmental behaviors and improved solid waste management (Zhang et al., 2015; Crociata et al., 2016; Cheirrito-Arruda et al., 2018). Determining the factors that may influence the intention to engage in pro-environmental behaviors may lay down insights into the factors that may contribute to the improvement of solid waste management practices (Tang et al., 2022). Understanding the factors influencing the intentions of the residents living along the Cotabato City rivers to implement pro-environmental behaviors may help craft research-based decisions, policies, and programs that may help enhance solid waste management. The role of residents living along these rivers is crucial in implementing pro-environmental behaviors and this can contribute to the conservation and protection of rivers. However, there is a gap in understanding the factors influencing the intentions to implement pro-environmental behaviors among the riverside communities in the Philippines, especially in Cotabato City.

This study employs the Theory of Planned Behavior to determine the factors influencing the intentions of the riverside communities in the Cotabato City rivers to implement pro-environmental behaviors. This study also investigated the moderating effects of gender in the intention to implement pro-environmental behaviors. The results of this study can help policymakers and stakeholders develop targeted interventions that promote pro-environmental behaviors and create sustainable communities along rivers.

Materials and Methods

Survey questionnaire design

A standard questionnaire was utilized to obtain the necessary data needed for identifying the socio-demographic profile and the factors affecting the intention to implement pro-environmental behaviors of the residents of the riverside communities along the Cotabato City rivers in Mindanao Island. The survey questionnaire includes the cover letter indicating the ethical issues regarding confidentiality, the demographic profile, and the items of each latent variable in the Theory of Planned Behavior (TPB) model. All items that were used to measure each latent variable in the TPB model were adapted from several published studies. Prior to the data collection, the survey questionnaire was submitted to the panel of experts for content and face validity. Then, a pre-test was conducted to determine the reliability and consistency of the items in the survey questionnaire through Cronbach’s alpha coefficient. Each item in the latent variable for the TPB model was measured using a five-point Likert scale (1 – Strongly disagree to 5 – Strongly agree). All items were written in English and then translated into Tagalog.

All of the respondents were duly informed about the purpose of the study, and informed consent was secured from them. The confidentiality and anonymity of the respondents were strictly complied with during the collection, analysis, and reporting of the data.

Description of the study area surveyed

The study was conducted in Cotabato City, Maguindanao del Norte, Mindanao Island (7.2047°N, 124.2310°E) (Figure 1). The area is surrounded and traversed by numerous rivers. The water from these rivers discharges to Ilana Bay, which is situated in the eastern portion of the city. The area is enriched with marine resources and is considered one of the top producers of crabs in the Bangsamoro Autonomous Region in Muslim Mindanao (BARMM) region annually (Fernandez, 2011). The population of Cotabato City as of 2020 is about 325,079 and is projected to be increasing. The riverside communities that were surveyed in this study were situated along the four (4) rivers that traverse Cotabato City. These rivers are Matampay, Tamonataka, Esteros, and Rio Grande de Mindanao Rivers which traverse fifteen (15) barangays; Bagua I, Bagua II, Bagua III, Kalanganan, Poblacion I, Poblacion II, Poblacion III, Poblacion V, Poblacion VI, Poblacion VII, Rosary Heights II, Rosary Heights VI, Rosary Heights X, Tamontaka I, and Tamontaka II. These communities were chosen due to accessibility and were located within and near the commercial center of the city, The riverside communities were surveyed from November 2022 to February 2023.

Respondents of the Study

The statistical population of this survey research includes all the residents of the riverside communities along the Matampay, Tamonataka, Esteros, and Rio Grande de Mindanao Rivers that traverse Cotabato City. In this regard, there were fifteen (15) barangays surveyed in this study and were classified based on the river that traverses their respective area. The number of samples to be included in this study was determined using an available sample size calculator for structural equation models by Soper (2023). This study applies a stratified random sample technique and each river was considered as a separate stratum. The riverside communities in each river were divided into twenty-one (21) quadrants, and in each quadrant six (6) households were randomly selected for the survey. The survey was conducted through face-to-face interviews.

A total of 504 survey questionnaires were prepared for the face-to-face interviews. However, only 99.4% of the respondents had only agreed and were interviewed using the prepared survey questionnaire.  Before data analysis, 42 responses were omitted due to several items were not answered or the items have a standard deviation of less than 0.3. Prior to structural equation modeling (SEM), responses that were considered multiple outliers were also determined using Mahanalobis distance and were removed. Only a total of 387 responses were considered valid and were used for SEM.

Structural Equation Modelling (SEM)

Microsoft Excel (2021) was used to encode the results of the survey. The SPSS 26 and AMOS 22 were utilized for the Structural Equation Modelling (SEM). SEM analyzed if the proposed model fits the collected data while considering the measurement errors at the same time (Fan et al., 2016). Since this study employs the Theory of Planned Behavior (TPB) model, five latent variables were considered. These were attitude (ATT), subjective norms (SN), perceived behavioral control (PBC), intention (IN), and pro-environmental behavior (PEB). In the survey questionnaire used for data collection, both the attitude (ATT) and the subjective norms (SN) have five items while the rest of the latent variables each have six items. All items used to measure each latent variable were adapted from published studies (Milfont and Duckitt, 2010; Hong et al., 2014; Jaiswal and Kant, 2018; Akitsu and Ishihara, 2018; Han and Cheng, 2020; Jacob et al., 2021; Gibson et al., 2021). Several Goodness-of-Fit (GOF) measures were used to assess if the model fits the data. The moderating effects of the gender (male and female) and the age group were determined using multi-group analysis.

Results and Discussion

Descriptive Characteristics of the Respondents

The demographic of the respondents (Table 1) shows that 67.6% are female. The distribution of respondents based on age is highest in 15-24 years old (40.3%) while least in 54-64 years old (8.8%). Most of the respondents were married (61.3%) and most have attained the elementary level only (44.4%). Most of the respondents were residing near or along the rivers for more than a decade (62.1%) and most had a household monthly income of less than P5,000.00 (79.3%).

Utilization of Cotabato City Rivers

Table 2 shows the manner of utilization of the Cotabato City rivers by the respondents. Most of the respondents utilized the rivers through the laundry (61.84%) and the washing of utensils (25.44%). This mode of utilization of the riverside communities along the Cotabato City rivers by the residents can be attributed to several factors such as lack of access to alternative facilities, economic considerations, cultural and traditional practices, perceived convenience, and lack of awareness regarding environmental impacts (Wang and He, 2022).

The Validity and Reliability of the Model

The model used in this study was evaluated using the composite reliability and construct validity (Table 3). Cronbach’s alpha reflects the reliability of the scales used in the survey questionnaire. The recommended threshold value for Cronbach’s alpha should be greater than 0.70. All Cronbach’s alpha values of the latent variables exceed the recommended threshold value (Table 3), thus the items for each variable are considered to be reliable. The internal consistency of each construct in the present study is reflected by the composite reliability (CR). The recommended value for the CR should be above 0.70 and all the constructs in the present study exceeded the threshold value (Table 3). To determine if the items used in this study truly measure their respective latent variables, construct validity was evaluated. The construct validity was determined using the factor loadings and the average variance extracted (AVE). The recommended level for the AVE should be more than 0.5 and it is used to assess the overall amount of variance in the items as accounted by the latent variable. The AVE of the latent variables in this study ranged from 0.642 to 0.727 (Table 3), thus exceeding the recommended threshold value. Table 4 shows the final factor loading of each item used to measure each latent variable in this study. Those items that did not reach the recommended threshold value will be omitted and all items that exceeded the recommended level of 0.6 were retained. Overall, the final model that was used in this study can be considered valid and reliable.

The overall fit of the model was determined using various fit indices (Table 5). The Chi-square was not used as one of the indices in this study due to its sensitivity to sample size (Bearden et al., 1982). The Goodness of Fit (GFI) and the Comparative Fit Index (CFI) were used to assess the overall fit of the proposed model (Hooper et al., 2008). The Incremental Fit Index (IFI), Tucker Lewis Index (TLI), and Adjusted Goodness of Fit Index (AGFI) were used to validate the fitness of the proposed model (Hooper et al., 2008). And the parsimonious fitness of the model used in this study was assessed using the Root Mean Square Error (RMSEA) (Hooper et al., 2008).  All the threshold values recommended for each fit indices used in this study and their respective observed values in the final model were indicated in Table 5. All the observed values exceeded the threshold value for each model fit index. Thus, the final model in this study fits the collected data.

Factors Affecting the Intentions to Implement Pro-environmental Behaviors

Upon the analysis of the results of the SEM (Figure 2), it was found that only the Subjective Norms (SN) (β = .612, p < 0.01) and Attitude (ATT) (β = .612, p < 0.01) were able to describe the variation in the Intention (IN) to implement pro-environmental behaviors (55%).  The Intention (IN) is also statistically significant towards Pro-environmental behavior (PEB) (β = 0.326, p < 0.01). However, the Perceived Behavioral Control (PBC) (β = .055, p > 0.01) is not statistically significant to Intention (IN). Applying the theory of planned behavior, only the Subjective Norms (SN) and the Attitude (ATT) have significant effects on the intentions of the respondents along the Cotabato City rivers to implement pro-environmental behaviors.

The findings of this study indicated that Subjective Norms (SN) have the most significant direct effects (0.612) toward intention (IN) to implement pro-environmental behaviors, compared to Attitude (ATT) (0.198).  The participation of the residents along the Cotabato City rivers in implementing pro-environmental behaviors is influenced by their social relations (Videras et al. 2012; Macias and Williams, 2014). Families and communities play a significant role in shaping individuals’ subjective norms regarding the implementation of pro-environmental behaviors (Gronhoj and Thogersen, 2012). Several studies had also indicated the significant effects of Subjective Norms (SN) on the intention to implement pro-environmental behaviors (see Onel, 2017; Han and Cheng, 2020; Warner, 2021). The findings of this study are also similar to the study conducted by Yang et al. (2020) where Subjective Norms (SN) have significant direct effects on the pro-environmental behavior towards haze mitigation in China. The result of this study is also consistent with the findings of Gumasing et al. (2023) in which the Subjective Norms (SN) have the highest significant effect on the pro-environmental behavioral intention of accepting renewable energy sources among Filipinos in the National Capital Region (NCR). However, the finding of this study differs from Suminguit et al. (2023) in which no significant direct effects on the Subjective Norms (SN) were noted on the Junior High School students at Notre Dame University, Cotabato City, Mindanao Island, Philippines to implement pro-environmental behaviors. The inconsistent results of subjective norms towards intention to implement pro-environmental behaviors might suggest that this variable might be vulnerable to internal and external factors involved in different studies (Vicente-Molina et al., 2013).

Attitude (ATT) is another significant contributor to the intention to implement pro-environmental policies among the residents of the riverside communities along the Cotabato City rivers. Contrary to the typical pattern observed in many Theory of Planned Behavior (TPB) model studies, where Attitude (ATT) is anticipated to have the most significant effect on Intention (IN), closely followed by Subjective Norms (SN), this study reveals a departure from this expected relationship (Leeuw et al., 2015). In this study, the respondents showed a positive attitude toward the intention to implement pro-environmental policies (mean on a scale of 1-5, with high numbers representing a positive attitude, 4.182). Moreover, the results of this study are also in line with other studies involving assessments of factors affecting the intention to implement pro-environmental behaviors (see Janmaimool and Khajohnmanee, 2019; Miller et al., 2022). A study conducted by Simpao and Yabut (2022) among university students in Metro Manila, Philippines indicated that attitude plays an important role in their environmental conservation behavior. The high extent of environmental attitude is also correlated with the high extent of pro-environmental behaviors (Hornejas, 2021). This paper and other studies conducted regarding the assessment of factors affecting the intention to implement pro-environmental policies suggest that Attitude (ATT) is an important factor in pro-environmental intentions.

Perceived Behavioral Control (PBC) was not found to be significantly impacting the intention to implement pro-environmental policies. This finding contradicts some other Theory of Planned Behavior studies involving the intention to implement pro-environmental policies (Chang et al., 2022; Galván-Mendoza et al., 2022; Kumar et al., 2022;). According to Sheeran et al. (2002), the strength of perceived behavioral control (PBC) toward intention (IN) may depend on the demographic profile of the respondents. This may be the reason the results of this study contradict most of the literature.  Moreover, the results of this study also point out that the respondents in the present study are not confident or in control in implementing pro-environmental behaviors (mean on a scale of 1-5, with high numbers representing a positive perceived behavioral control, 2.79). To improve the perceived behavioral control of the respondents, concerned government agencies and stakeholders may educate the individuals residing along the Cotabato City rivers regarding the positive impacts of implementing pro-environmental behaviors (Grilli and Curtis, 2019).

Moderating Effects of Gender

Table 6 shows the moderating effects of the gender (male and female) among the relationships in the final model. However, only the Perceived Behavioral Control (PBC) toward Intentions (IN) to implement pro-environmental behaviors was found to have a significant difference between males and females (p = 0.025). Males had found to have a weak negative Perceived Behavioral Control (PBC) (path coefficient = -0.031) compared to females (path coefficient = 0.118).

The results of this study coincide with the other studies that investigated the moderating effects of gender (male and female) towards the intention to implement pro-environmental behaviors (Schahn, et al. 1990; Dagher et al., 2015; Karimi et al., 2022). According to Xiao and McCright (2013), women have stronger pro-environmental values and knowledge than men and this claim was also supported by several studies (Zelezny et al., 2000; Li et al., 2022). Pro-environmental knowledge was also found to have significant effects and can enhance perceived behavioral control (PBC) (Galvan-Mendoza et al., 2022). This may be the possible reason for the high perceived behavioral control (PBC) of females compared to males in the present study but further studies should be conducted to verify this claim.

Conclusion

This paper analyzes the factors affecting the intentions to implement pro-environmental behaviors in the riverside communities along Cotabato City rivers using the Theory of Planned Behavior. This study also investigated the mediating role of gender in attitude (ATT), subjective norms (SN), and perceived behavioral control (PBC) towards the intention to implement pro-environmental behaviors. It was found that among the factors affecting the intention to implement pro-environmental behaviors, only the perceived behavioral control (PBC) has no significant direct effects on the intention to implement pro-environmental behaviors. The perceived behavioral control is stronger in females and is significantly different in males. This study may draw some important policy implications for environmental protection in the Cotabato City rivers. The policy design to promote the resident’s intention to implement pro-environmental behaviors should consider these factors to enhance the ability of the riverside communities to conduct pro-environmental behaviors. Concerned government agencies and other stakeholders may also conduct education and awareness campaigns tailored specifically for males, emphasizing the benefits and feasibility of implementing pro-environmental behaviors for Cotabato City river protection and conservation. Since there are different internal and external factors that may affect the intention to implement pro-environmental behaviors, it is recommended for future studies extend the TPB model used in this study to further examine the factors affecting the intention to implement pro-environmental behaviors.

Acknowledgments

The authors would like to extend their sincerest gratitude to the Ministry of Science and Technology, Bangsamoro Autonomous Region in Muslim Mindanao (MOST-BARMM) for funding this research. Appreciation is also extended to the Barangay Local Government Units of Cotabato City for supporting the team during the conduct of the study.

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