The coastal region of Bangladesh is significantly influenced by soil and water salinity, which is further exacerbated by the increasing frequency of tropical cyclones and rising sea levels. Understanding the extent of salinity and its challenges is crucial for promoting sustainable agriculture and ensuring access to safe drinking water. Using quantitative (soil and water parameters) and qualitative (focus group discussion and key informant interview) data, we investigated (i) soil and water salinity and soil nutrient contents; and (ii) adaptive practices in agriculture and drinking water management in three sub-districts (Assasuni, Dacope and Morrelganj) in the southwestern coastal region of Bangladesh. Results show that soil salinity levels did not significantly differ among the sub-districts, with Assasuni having slightly higher soil salinity (8.24 dS m-1) compared to Dacope (8.08 dS m-1) and Morrelganj (7.96 dS m-1). Significant differences were observed in the salinity level of pond and canal water among the sub-districts, with Assasuni having the highest levels of salinity in both pond (13.98 dS m-1) and canal water (77.85 dS m-1), compared to other sub-districts. Soil and water salinity were the major challenges reported by the respondents; however, climate-induced stresses (e.g., untimely precipitation) and outbreaks of pests during droughts have been identified as prominent issues in sustainable agriculture. Rainwater harvesting has been identified as a viable adaptive technique in drinking water management, offering a feasible solution to address water and soil salinity. The study underscores the importance of implementing adaptive practices (e.g., rainwater harvesting) to address water scarcity and salinity issues in the coastal region and promote resilient agricultural systems.
{"title":"Strengthening adaptation in coastal Bangladesh: community-based approaches for sustainable agriculture and water management","authors":"Khusnur Jahan Shapna, Jianfeng Li, Md Humayain Kabir, Mohammed Abdus Salam, Saifullah Khandker, Md Lokman Hossain","doi":"10.20517/dpr.2023.41","DOIUrl":"https://doi.org/10.20517/dpr.2023.41","url":null,"abstract":"The coastal region of Bangladesh is significantly influenced by soil and water salinity, which is further exacerbated by the increasing frequency of tropical cyclones and rising sea levels. Understanding the extent of salinity and its challenges is crucial for promoting sustainable agriculture and ensuring access to safe drinking water. Using quantitative (soil and water parameters) and qualitative (focus group discussion and key informant interview) data, we investigated (i) soil and water salinity and soil nutrient contents; and (ii) adaptive practices in agriculture and drinking water management in three sub-districts (Assasuni, Dacope and Morrelganj) in the southwestern coastal region of Bangladesh. Results show that soil salinity levels did not significantly differ among the sub-districts, with Assasuni having slightly higher soil salinity (8.24 dS m-1) compared to Dacope (8.08 dS m-1) and Morrelganj (7.96 dS m-1). Significant differences were observed in the salinity level of pond and canal water among the sub-districts, with Assasuni having the highest levels of salinity in both pond (13.98 dS m-1) and canal water (77.85 dS m-1), compared to other sub-districts. Soil and water salinity were the major challenges reported by the respondents; however, climate-induced stresses (e.g., untimely precipitation) and outbreaks of pests during droughts have been identified as prominent issues in sustainable agriculture. Rainwater harvesting has been identified as a viable adaptive technique in drinking water management, offering a feasible solution to address water and soil salinity. The study underscores the importance of implementing adaptive practices (e.g., rainwater harvesting) to address water scarcity and salinity issues in the coastal region and promote resilient agricultural systems.","PeriodicalId":479615,"journal":{"name":"Disaster Prevention and Resilience","volume":"124 33","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141115544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Spectral stochastic finite element (SSFE) has been widely used in the uncertainty quantification of real-life problems. However, the prohibitive computational burden prevents the application of the method in practical engineering systems because an enormous augmented system has to be solved. Although the domain decomposition method has been introduced to SSFE to improve the efficiency for the solution of the augmented system, there still exist significant challenges in solving the extended Schur complement (e-SC) system from domain decomposition method. In this paper, we develop an approximate sparse expansion-based domain decomposition solver to generalize the application of SSFE. An approximate sparse expansion is first presented for the subdomain-level augmented matrix so that the computational cost in each iteration of the preconditioned conjugate gradient is greatly alleviated. Based on the developed sparse expansion, we further establish an approximate sparse preconditioner to accelerate the convergence of the preconditioned conjugate gradient. The developed approximate sparse expansion-based domain decomposition solver is then incorporated in the context of SSFE. Since the difficulties of solving the e-SC system have been overcome, the developed approximate sparse expansion-based solver greatly improves the computational efficiency of the solution of the e-SC system, and thereby, the SSFE is capable of dealing with large-scale engineering systems. Two numerical examples demonstrate that the developed method can significantly enhance the efficiency for the stochastic response analysis of practical engineering systems.
{"title":"A domain decomposition solver for spectral stochastic finite element: an approximate sparse expansion approach","authors":"Bowen Luo, Wen Cao, Zheng Zhou, Hongzhe Dai","doi":"10.20517/dpr.2023.39","DOIUrl":"https://doi.org/10.20517/dpr.2023.39","url":null,"abstract":"Spectral stochastic finite element (SSFE) has been widely used in the uncertainty quantification of real-life problems. However, the prohibitive computational burden prevents the application of the method in practical engineering systems because an enormous augmented system has to be solved. Although the domain decomposition method has been introduced to SSFE to improve the efficiency for the solution of the augmented system, there still exist significant challenges in solving the extended Schur complement (e-SC) system from domain decomposition method. In this paper, we develop an approximate sparse expansion-based domain decomposition solver to generalize the application of SSFE. An approximate sparse expansion is first presented for the subdomain-level augmented matrix so that the computational cost in each iteration of the preconditioned conjugate gradient is greatly alleviated. Based on the developed sparse expansion, we further establish an approximate sparse preconditioner to accelerate the convergence of the preconditioned conjugate gradient. The developed approximate sparse expansion-based domain decomposition solver is then incorporated in the context of SSFE. Since the difficulties of solving the e-SC system have been overcome, the developed approximate sparse expansion-based solver greatly improves the computational efficiency of the solution of the e-SC system, and thereby, the SSFE is capable of dealing with large-scale engineering systems. Two numerical examples demonstrate that the developed method can significantly enhance the efficiency for the stochastic response analysis of practical engineering systems.","PeriodicalId":479615,"journal":{"name":"Disaster Prevention and Resilience","volume":"63 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140365734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Although seismic design concepts integrated the idea of shallow rocking foundations as an effective way to dissipate the induced seismic energy, a practical design solution is yet to be established. To attain this objective, it is necessary to identify the key parameters that govern the rocking efficacy of foundation and eventually overall seismic performance of the entire structure. The primary focus of this study is to assess the key parameters such as soil type and embedment depth of footing in conjunction with varying rocking foundation efficacy on the seismic force and displacement demands of the Reinforced Concrete (RC) buildings. A simplified generic high rise RC building along with its foundation is considered for the analytical study which is designed and detailed as per relevant Indian Standards. To highlight the beneficial effects of rocking foundation, seismic responses of the RC buildings with varying foundation rocking efficacy are compared with the conventional foundation design philosophies by conducting nonlinear dynamic time history analyses. From the seismic responses, it is determined that the moment from column to foundation and base shear, owing to seismic action, decreases with an increasing settlement at the base of the foundation for rocking footing. It is also observed from the seismic responses that rocking foundations effectively de-amplifies the peak roof acceleration by utilizing the nonlinear soil responses during earthquakes. Hence, it can be depicted that the foundation rocking improves the overall stability of the buildings by decreasing the seismic force demands with a slight increase in seismic displacement demands. The investigation also indicates that the efficacy of rocking foundation is not sensitive to embedment depth of footing.
{"title":"Isolated shallow rocking foundation on different soils with varying embedment depth","authors":"R. M. Kannan, P. Haldar, N. James","doi":"10.20517/dpr.2023.29","DOIUrl":"https://doi.org/10.20517/dpr.2023.29","url":null,"abstract":"Although seismic design concepts integrated the idea of shallow rocking foundations as an effective way to dissipate the induced seismic energy, a practical design solution is yet to be established. To attain this objective, it is necessary to identify the key parameters that govern the rocking efficacy of foundation and eventually overall seismic performance of the entire structure. The primary focus of this study is to assess the key parameters such as soil type and embedment depth of footing in conjunction with varying rocking foundation efficacy on the seismic force and displacement demands of the Reinforced Concrete (RC) buildings. A simplified generic high rise RC building along with its foundation is considered for the analytical study which is designed and detailed as per relevant Indian Standards. To highlight the beneficial effects of rocking foundation, seismic responses of the RC buildings with varying foundation rocking efficacy are compared with the conventional foundation design philosophies by conducting nonlinear dynamic time history analyses. From the seismic responses, it is determined that the moment from column to foundation and base shear, owing to seismic action, decreases with an increasing settlement at the base of the foundation for rocking footing. It is also observed from the seismic responses that rocking foundations effectively de-amplifies the peak roof acceleration by utilizing the nonlinear soil responses during earthquakes. Hence, it can be depicted that the foundation rocking improves the overall stability of the buildings by decreasing the seismic force demands with a slight increase in seismic displacement demands. The investigation also indicates that the efficacy of rocking foundation is not sensitive to embedment depth of footing.","PeriodicalId":479615,"journal":{"name":"Disaster Prevention and Resilience","volume":"50 26","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140487438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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