Pub Date : 2021-12-29DOI: 10.1080/15715124.2021.2021926
V. Tri, Phan Ky Trung, T. Trong, D. Parsons, S. Darby
ABSTRACT Climate change and trans-boundary development in the major deltas of the world, including the Vietnamese Mekong Delta have exacerbated environmental risks. Land subsidence, riverbed sand mining, and intensive groundwater extraction have all contributed to lower channel bed levels, resulting in riverbank erosion and the loss of assets and livelihoods for local residents. This study investigated the drivers, and classified the social vulnerability of local communities affected by riverbank erosion along two main branches in the Vietnamese Mekong. Direct interviews were conducted with 218 erosion-affected households along the Mekong and Bassac rivers in Dong Thap and An Giang provinces in order to create a social vulnerability index. More than 70% of the total surveyed households belonged to the highly, moderately, or low vulnerability groups, suggesting a range of affected communities within the sample, some of whom had the ability to cope with its short-term impacts. However, the estimated social vulnerability index revealed significant geographical heterogeneity, with communities along the Mekong branch being more vulnerable than those along the Bassac. The recommendations from our investigations include the establishment of community awareness programmes, as well as policy changes that ensure and support local residents’ livelihoods adaptation. Stakeholder participation and enhanced community engagement was found to be the most important tools available in terms of aiding local people cope with the complex impacts of riverbank erosion.
{"title":"Assessing social vulnerability to riverbank erosion across the Vietnamese Mekong Delta","authors":"V. Tri, Phan Ky Trung, T. Trong, D. Parsons, S. Darby","doi":"10.1080/15715124.2021.2021926","DOIUrl":"https://doi.org/10.1080/15715124.2021.2021926","url":null,"abstract":"ABSTRACT Climate change and trans-boundary development in the major deltas of the world, including the Vietnamese Mekong Delta have exacerbated environmental risks. Land subsidence, riverbed sand mining, and intensive groundwater extraction have all contributed to lower channel bed levels, resulting in riverbank erosion and the loss of assets and livelihoods for local residents. This study investigated the drivers, and classified the social vulnerability of local communities affected by riverbank erosion along two main branches in the Vietnamese Mekong. Direct interviews were conducted with 218 erosion-affected households along the Mekong and Bassac rivers in Dong Thap and An Giang provinces in order to create a social vulnerability index. More than 70% of the total surveyed households belonged to the highly, moderately, or low vulnerability groups, suggesting a range of affected communities within the sample, some of whom had the ability to cope with its short-term impacts. However, the estimated social vulnerability index revealed significant geographical heterogeneity, with communities along the Mekong branch being more vulnerable than those along the Bassac. The recommendations from our investigations include the establishment of community awareness programmes, as well as policy changes that ensure and support local residents’ livelihoods adaptation. Stakeholder participation and enhanced community engagement was found to be the most important tools available in terms of aiding local people cope with the complex impacts of riverbank erosion.","PeriodicalId":14344,"journal":{"name":"International Journal of River Basin Management","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2021-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44169513","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}
Pub Date : 2021-12-16DOI: 10.1080/15715124.2021.2016781
Ismahen Kadri, R. Mansouri, Amir Aieb
ABSTRACT This paper presents a comparison between the black box Nonlinear Auto-Regressive with eXogenous inputs-Neural Network (NARX-NN) and the conceptual Hydrologic Engineering Centre-Hydrologic Modelling System (HEC-HMS) Rainfall-Runoff models. The two models were applied on a small urban watershed to assess its response to fourteen hourly real storm events. The differences between the steps engaged in each model to reach the hydrograph were presented in detail. The estimation of the best parameters is carried out using a weighted average function during the calibration phase. A statistical evaluation was conducted to assess the model’s performance thereafter; a critical comparison was made to illustrate the differences and discuss the steps involved. The results indicate that both models successfully reflect the urban basin runoff. However, the NARX-NN outperforms in the testing phase owing to their strength generalization feature. The NARX-NN model has more strength to produce the shape bending of the hydrograph. Consequently, this model is better to highlight the curvatures resulting from the local peaks of rainfall.
{"title":"Comparison between NARX-NN and HEC-HMS models to simulate Wadi Seghir catchment runoff events in Algerian northern","authors":"Ismahen Kadri, R. Mansouri, Amir Aieb","doi":"10.1080/15715124.2021.2016781","DOIUrl":"https://doi.org/10.1080/15715124.2021.2016781","url":null,"abstract":"ABSTRACT\u0000 This paper presents a comparison between the black box Nonlinear Auto-Regressive with eXogenous inputs-Neural Network (NARX-NN) and the conceptual Hydrologic Engineering Centre-Hydrologic Modelling System (HEC-HMS) Rainfall-Runoff models. The two models were applied on a small urban watershed to assess its response to fourteen hourly real storm events. The differences between the steps engaged in each model to reach the hydrograph were presented in detail. The estimation of the best parameters is carried out using a weighted average function during the calibration phase. A statistical evaluation was conducted to assess the model’s performance thereafter; a critical comparison was made to illustrate the differences and discuss the steps involved. The results indicate that both models successfully reflect the urban basin runoff. However, the NARX-NN outperforms in the testing phase owing to their strength generalization feature. The NARX-NN model has more strength to produce the shape bending of the hydrograph. Consequently, this model is better to highlight the curvatures resulting from the local peaks of rainfall.","PeriodicalId":14344,"journal":{"name":"International Journal of River Basin Management","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2021-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44982407","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}
Pub Date : 2021-12-16DOI: 10.1080/15715124.2021.2016782
Rohan Kar, Arindam Sarkar
ABSTRACT The study proposes an efficient method to evaluate the suspended sediment concentration (SSC) relative to the traditional sediment rating curves (SRC) for gauged stations and subsequently to predict the SSC in ungauged stations of a major river basin. Multiple environmental control parameters were collected from 16 stations along the Mahanadi River basin (MRB) during the monsoon season. The hysteresis behaviour of SSC is assessed and therefore considered for modelling SSC using linear mixed-effects modelling (LMM). A basin-scale rating model is proposed using principal component analysis and stepwise multiple linear regression for estimating the unmeasured SSC. The findings show that the MRB acts differently in terms of hysteresis, with distinct dilution and flushing regimes in SRC. LMM outscored SRC by nearly doubling the mean covariance and notably reducing the percent bias between observed and predicted data across stations. However, unlike LMM, SRC could not correctly estimate low and high SSCs of ≤ 0.05 g/l and ≥ 1.5 g/l, respectively. The error metrics of the proposed rating model are within acceptable limits for all ungauged stations. Nevertheless, its efficiency varies due to smaller catchment areas, non-linearity in sediment transport with respect to catchment area, and other sampling issues. As a result, compared to other known models applied on the MRB, this model has the lowest error and seems to be the best in predicting monthly SSC.
{"title":"Potential predictability of suspended sediment concentration in the data constrained regions of the Mahanadi River basin, Eastern India","authors":"Rohan Kar, Arindam Sarkar","doi":"10.1080/15715124.2021.2016782","DOIUrl":"https://doi.org/10.1080/15715124.2021.2016782","url":null,"abstract":"ABSTRACT The study proposes an efficient method to evaluate the suspended sediment concentration (SSC) relative to the traditional sediment rating curves (SRC) for gauged stations and subsequently to predict the SSC in ungauged stations of a major river basin. Multiple environmental control parameters were collected from 16 stations along the Mahanadi River basin (MRB) during the monsoon season. The hysteresis behaviour of SSC is assessed and therefore considered for modelling SSC using linear mixed-effects modelling (LMM). A basin-scale rating model is proposed using principal component analysis and stepwise multiple linear regression for estimating the unmeasured SSC. The findings show that the MRB acts differently in terms of hysteresis, with distinct dilution and flushing regimes in SRC. LMM outscored SRC by nearly doubling the mean covariance and notably reducing the percent bias between observed and predicted data across stations. However, unlike LMM, SRC could not correctly estimate low and high SSCs of ≤ 0.05 g/l and ≥ 1.5 g/l, respectively. The error metrics of the proposed rating model are within acceptable limits for all ungauged stations. Nevertheless, its efficiency varies due to smaller catchment areas, non-linearity in sediment transport with respect to catchment area, and other sampling issues. As a result, compared to other known models applied on the MRB, this model has the lowest error and seems to be the best in predicting monthly SSC.","PeriodicalId":14344,"journal":{"name":"International Journal of River Basin Management","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2021-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49322141","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}
Pub Date : 2021-12-16DOI: 10.1080/15715124.2021.2016783
A. M. Bento, A. Gomes, J. P. Pêgo, T. Viseu, Lúcia Couto
ABSTRACT Understanding the risks associated with the likelihood of extreme events and their respective consequences for the stability of hydraulic infrastructures is essential for flood forecasting and engineering design purposes. Accordingly, a hydrological methodology for providing reliable estimates of extreme discharge flows approaching hydraulic infrastructures was developed. It is composed of a preliminary assessment of missing data, quality and reliability for statistically assessing the frequency of flood flows, allied to parametric and non-parametric methods. Model and parameter uncertainties are accounted for by the introduced and proposed modified model averaging (modified MM) approach in the extreme hydrological event's prediction. An assessment of the parametric methods accuracy was performed by using the non-parametric Kernel Density Estimate (KDE) as a benchmark model. For demonstration and validity purposes, this methodology was applied to estimate the design floods approaching the case study ‘new Hintze Ribeiro bridge’, located in the Douro river, one of the three main rivers in Portugal, and having one of Europe's largest river flood flows. Given the obtained results, the modified MM is considered a better estimation method.
{"title":"Improved assessment of maximum streamflow for risk management of hydraulic infrastructures. A case study","authors":"A. M. Bento, A. Gomes, J. P. Pêgo, T. Viseu, Lúcia Couto","doi":"10.1080/15715124.2021.2016783","DOIUrl":"https://doi.org/10.1080/15715124.2021.2016783","url":null,"abstract":"ABSTRACT Understanding the risks associated with the likelihood of extreme events and their respective consequences for the stability of hydraulic infrastructures is essential for flood forecasting and engineering design purposes. Accordingly, a hydrological methodology for providing reliable estimates of extreme discharge flows approaching hydraulic infrastructures was developed. It is composed of a preliminary assessment of missing data, quality and reliability for statistically assessing the frequency of flood flows, allied to parametric and non-parametric methods. Model and parameter uncertainties are accounted for by the introduced and proposed modified model averaging (modified MM) approach in the extreme hydrological event's prediction. An assessment of the parametric methods accuracy was performed by using the non-parametric Kernel Density Estimate (KDE) as a benchmark model. For demonstration and validity purposes, this methodology was applied to estimate the design floods approaching the case study ‘new Hintze Ribeiro bridge’, located in the Douro river, one of the three main rivers in Portugal, and having one of Europe's largest river flood flows. Given the obtained results, the modified MM is considered a better estimation method.","PeriodicalId":14344,"journal":{"name":"International Journal of River Basin Management","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2021-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48470649","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}
Pub Date : 2021-12-13DOI: 10.1080/15715124.2021.2016780
P. Soni, Pushpraj Singh
ABSTRACT Assessment and management of river water resources are essential to sustain life on the earth. Wetlands are the richest habitats sharing the large population of the existing living organisms. The river is a vital protection habitat due to rich biodiversity. The abundance, richness, diversity of various organisms are frequently used as an indicator for determining physicochemical and biological properties of the river as a wetland habitat. Therefore, the river basin areas should be evaluated for suitability for household, agricultural and industrial use. Untreated discharge of water in the river causes many problems not only for aquatic but also for human beings. So, the seasonal water pollution is a highly demandable subject and requires the water quality index. In the present study, the river water samples were collected from the selected twenty locations of the Arpa River to observe the physicochemical investigations such as temperature, pH, Dissolve Oxygen, Biological Oxygen Demand, Total Dissolved Solids, phosphate, and nitrate per the standard protocol. The present study depicted that water quality of the Arpa River was not suitable for human consumption. The Arpa River needs continuous monitoring because it is filled with the garbage and other waste material and encroached by the local people for fishing, bathing, and may anthropogenic activities, etc. The findings of the present work may help for the physicochemical investigation of new researchers and governing bodies for the sustainable supervision and protection of river water resources in the Arpa River basin.
{"title":"A water quality assessment of Arpa River under Bilaspur-Arpa basin area, of Chhattisgarh state","authors":"P. Soni, Pushpraj Singh","doi":"10.1080/15715124.2021.2016780","DOIUrl":"https://doi.org/10.1080/15715124.2021.2016780","url":null,"abstract":"ABSTRACT Assessment and management of river water resources are essential to sustain life on the earth. Wetlands are the richest habitats sharing the large population of the existing living organisms. The river is a vital protection habitat due to rich biodiversity. The abundance, richness, diversity of various organisms are frequently used as an indicator for determining physicochemical and biological properties of the river as a wetland habitat. Therefore, the river basin areas should be evaluated for suitability for household, agricultural and industrial use. Untreated discharge of water in the river causes many problems not only for aquatic but also for human beings. So, the seasonal water pollution is a highly demandable subject and requires the water quality index. In the present study, the river water samples were collected from the selected twenty locations of the Arpa River to observe the physicochemical investigations such as temperature, pH, Dissolve Oxygen, Biological Oxygen Demand, Total Dissolved Solids, phosphate, and nitrate per the standard protocol. The present study depicted that water quality of the Arpa River was not suitable for human consumption. The Arpa River needs continuous monitoring because it is filled with the garbage and other waste material and encroached by the local people for fishing, bathing, and may anthropogenic activities, etc. The findings of the present work may help for the physicochemical investigation of new researchers and governing bodies for the sustainable supervision and protection of river water resources in the Arpa River basin.","PeriodicalId":14344,"journal":{"name":"International Journal of River Basin Management","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46534868","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}
Pub Date : 2021-12-03DOI: 10.1080/15715124.2021.2002347
Dani Benchamin, S. R., Beena S. Kurup
ABSTRACT The perennial Kallada River originates at Karimalai-Kodakkal in the Southern part of Sahyadri (Western Ghats), running through Kollam, Pathanamthitta, and Trivandrum districts of Kerala, India. One of the crucial World Bank aided and the most significant Irrigation projects in Kerala is centred on the Kallada River, and now this project is benefited for in 92 villages. However, it is essential to monitor the water quality of the Kallada River. The focus of the present study is to assess the water quality of the Kallada River using caddisflies (Trichoptera) as well as physicochemical parameters of water. Samples of caddisflies and water were collected from 6 sites in the river to monitor water quality during the pre-monsoon season. Altogether, more than 3000 specimens belonging to 5 different taxa were recorded. A multivariate statistical approach was applied to study the influences of the water quality on caddisflies fauna. The results indicate that the upstream supported community abundance than the downstream. Less abundance of caddisflies was observed in the midstream and downstream sites Punalur and West Kallada, respectively. Caddisflies were absent in the sixth site Koivila, resulting from saltwater intrusion from the Ashtamudy estuary and various anthropogenic activities such as boating, civic effluents, and fishing. Upstream sites showed good water quality conditions and caddisfly abundance. The Kallada River is under threat of anthropogenic disturbances, especially in the mid and downstream sections. The caddisfly assemblage proved to be suitable in identifying variations in water quality conditions in the Kallada River because of their significant responses to environmental fluctuations.
{"title":"Utility of caddisflies (Insecta: Trichoptera) as indicators of water quality in Kallada River, Kerala, India","authors":"Dani Benchamin, S. R., Beena S. Kurup","doi":"10.1080/15715124.2021.2002347","DOIUrl":"https://doi.org/10.1080/15715124.2021.2002347","url":null,"abstract":"ABSTRACT The perennial Kallada River originates at Karimalai-Kodakkal in the Southern part of Sahyadri (Western Ghats), running through Kollam, Pathanamthitta, and Trivandrum districts of Kerala, India. One of the crucial World Bank aided and the most significant Irrigation projects in Kerala is centred on the Kallada River, and now this project is benefited for in 92 villages. However, it is essential to monitor the water quality of the Kallada River. The focus of the present study is to assess the water quality of the Kallada River using caddisflies (Trichoptera) as well as physicochemical parameters of water. Samples of caddisflies and water were collected from 6 sites in the river to monitor water quality during the pre-monsoon season. Altogether, more than 3000 specimens belonging to 5 different taxa were recorded. A multivariate statistical approach was applied to study the influences of the water quality on caddisflies fauna. The results indicate that the upstream supported community abundance than the downstream. Less abundance of caddisflies was observed in the midstream and downstream sites Punalur and West Kallada, respectively. Caddisflies were absent in the sixth site Koivila, resulting from saltwater intrusion from the Ashtamudy estuary and various anthropogenic activities such as boating, civic effluents, and fishing. Upstream sites showed good water quality conditions and caddisfly abundance. The Kallada River is under threat of anthropogenic disturbances, especially in the mid and downstream sections. The caddisfly assemblage proved to be suitable in identifying variations in water quality conditions in the Kallada River because of their significant responses to environmental fluctuations.","PeriodicalId":14344,"journal":{"name":"International Journal of River Basin Management","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2021-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48521857","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}
Pub Date : 2021-11-26DOI: 10.1080/15715124.2021.2007936
B. Burrell, S. Beltaos, B. Turcotte
ABSTRACT As the climate changes, ice characteristics and river-ice processes are altered, sometimes in unexpected ways. A warmer climate will obviously result in less ice globally, and in a general northward shift in the limits of seasonal river-ice occurrence. However, in several watersheds, the frequency of midwinter breakup events and the intensity of breakup ice jams may also change. In addition, climate change will alter other river-ice processes such as ice formation, freeze-up jams, and hanging dams. This is of concern during the design and construction of infrastructure as well as during the planning and implementation of flood-damage-reduction measures in and along rivers with seasonal ice covers. Changes in river-ice regimes will also alter the ecology of many lotic systems. The paper reviews the potential effects of a changing climate on river-ice properties and processes, and provides a discussion of future outcomes and their significance, as well as a suggested direction for future cold-regions river research.
{"title":"Effects of climate change on river-ice processes and ice jams","authors":"B. Burrell, S. Beltaos, B. Turcotte","doi":"10.1080/15715124.2021.2007936","DOIUrl":"https://doi.org/10.1080/15715124.2021.2007936","url":null,"abstract":"ABSTRACT As the climate changes, ice characteristics and river-ice processes are altered, sometimes in unexpected ways. A warmer climate will obviously result in less ice globally, and in a general northward shift in the limits of seasonal river-ice occurrence. However, in several watersheds, the frequency of midwinter breakup events and the intensity of breakup ice jams may also change. In addition, climate change will alter other river-ice processes such as ice formation, freeze-up jams, and hanging dams. This is of concern during the design and construction of infrastructure as well as during the planning and implementation of flood-damage-reduction measures in and along rivers with seasonal ice covers. Changes in river-ice regimes will also alter the ecology of many lotic systems. The paper reviews the potential effects of a changing climate on river-ice properties and processes, and provides a discussion of future outcomes and their significance, as well as a suggested direction for future cold-regions river research.","PeriodicalId":14344,"journal":{"name":"International Journal of River Basin Management","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2021-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49539117","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}
Pub Date : 2021-11-17DOI: 10.1080/15715124.2021.2002345
H. Darko, A. Karikari, A. Duah, B. A. Akurugu, Victor Mante, Frank Oblim Teye
ABSTRACT In Ghana, small-scale mining (SSM) has been carried out for many years, generating employment and income. Currently, illegal artisanal mining (‘galamsey’) has impacted the environment negatively, resulting in land degradation and water pollution. The government of Ghana, responding to public outcry against the negative effects of ‘galamsey’, placed a ban on illegal small-scale mining activities in March 2017. This ban stopped both ‘legal’ small-scale and the illegal artisanal miners from carrying out any such activity. In July 2018, this study was carried out to examine the status of water and sediment quality in eight endemic regions of illegal mining to ascertain the outcome of the ban on the water quality of the rivers. Methodologies in the Standard Methods for the Examination of Water and Wastewater were followed. Results of the study indicated that the rivers were high in total suspended solids (TSS), turbidity and colour, suggesting inflow of wastewater from the illegal mining activities and some run-off. Colour had a strong correlation with turbidity (r = 0.95) and TSS (r = 0.94), suggesting that the pollution originates from the same sources. Low levels of metals were found in both water and sediment. However, very high concentrations of Fe were detected in both water and sediment. Mercury concentrations were low in the water column but relatively higher in the sediment. A comparison of the general water quality status of the water bodies in the Pra Basin in 2013 and 2018 using the Water Quality Index (WQI) showed a marginal improvement in quality in 2018 over 2013 in the Pra Basin. The improvement of water quality in 2018 is attributable to the ban.
{"title":"Effect of small-scale illegal mining on surface water and sediment quality in Ghana","authors":"H. Darko, A. Karikari, A. Duah, B. A. Akurugu, Victor Mante, Frank Oblim Teye","doi":"10.1080/15715124.2021.2002345","DOIUrl":"https://doi.org/10.1080/15715124.2021.2002345","url":null,"abstract":"ABSTRACT In Ghana, small-scale mining (SSM) has been carried out for many years, generating employment and income. Currently, illegal artisanal mining (‘galamsey’) has impacted the environment negatively, resulting in land degradation and water pollution. The government of Ghana, responding to public outcry against the negative effects of ‘galamsey’, placed a ban on illegal small-scale mining activities in March 2017. This ban stopped both ‘legal’ small-scale and the illegal artisanal miners from carrying out any such activity. In July 2018, this study was carried out to examine the status of water and sediment quality in eight endemic regions of illegal mining to ascertain the outcome of the ban on the water quality of the rivers. Methodologies in the Standard Methods for the Examination of Water and Wastewater were followed. Results of the study indicated that the rivers were high in total suspended solids (TSS), turbidity and colour, suggesting inflow of wastewater from the illegal mining activities and some run-off. Colour had a strong correlation with turbidity (r = 0.95) and TSS (r = 0.94), suggesting that the pollution originates from the same sources. Low levels of metals were found in both water and sediment. However, very high concentrations of Fe were detected in both water and sediment. Mercury concentrations were low in the water column but relatively higher in the sediment. A comparison of the general water quality status of the water bodies in the Pra Basin in 2013 and 2018 using the Water Quality Index (WQI) showed a marginal improvement in quality in 2018 over 2013 in the Pra Basin. The improvement of water quality in 2018 is attributable to the ban.","PeriodicalId":14344,"journal":{"name":"International Journal of River Basin Management","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2021-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49438921","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}
Pub Date : 2021-11-12DOI: 10.1080/15715124.2021.2005614
Fatemeh Maleki, S. Abbasi
ABSTRACT Local scour control around the groins is one of the most important designs and construction factors. In this study, a new radial arrangement style of permeable groins Permeable Groins with Radial Arrangement (PGRA) is introduced and the performance of the groins in this layout is compared to that of the traditional straight arrangement of groins in one and two rows. 90 experiments were performed using permeability of 40%, 60 and 80 per cent and two different discharges. The clear water condition with smooth and homogenous bed sediment materials was considered. The results show that groins arrangement permeability rate and flow discharge affect the sediment conditions around the groins. The most effective arrangement in reduction of scour depth is PGRA with 7 piles in which the scour depth is reduced by 75%, 80% and 66% in permeability rates of 40%, 60% and 80%, respectively.
{"title":"Influence of permeable groins with radial arrangement on local scour around groins: an experimental study","authors":"Fatemeh Maleki, S. Abbasi","doi":"10.1080/15715124.2021.2005614","DOIUrl":"https://doi.org/10.1080/15715124.2021.2005614","url":null,"abstract":"ABSTRACT\u0000 Local scour control around the groins is one of the most important designs and construction factors. In this study, a new radial arrangement style of permeable groins Permeable Groins with Radial Arrangement (PGRA) is introduced and the performance of the groins in this layout is compared to that of the traditional straight arrangement of groins in one and two rows. 90 experiments were performed using permeability of 40%, 60 and 80 per cent and two different discharges. The clear water condition with smooth and homogenous bed sediment materials was considered. The results show that groins arrangement permeability rate and flow discharge affect the sediment conditions around the groins. The most effective arrangement in reduction of scour depth is PGRA with 7 piles in which the scour depth is reduced by 75%, 80% and 66% in permeability rates of 40%, 60% and 80%, respectively.","PeriodicalId":14344,"journal":{"name":"International Journal of River Basin Management","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2021-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47116390","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}
Pub Date : 2021-11-09DOI: 10.1080/15715124.2021.2002346
L. Santarosa, Didier Gastmans, T. Gilmore, J. Boll, S. Betancur, Vitor Fidelis Monteiro Gonçalves
ABSTRACT Changes in climate and water demand in densely populated regions increasingly affect hydrological systems, and, in turn, impact socioeconomic conditions. In this case study, we identify how the hydrogeological frameworks of two water resource management units, Tietê-Jacaré (TJ) and Piracicaba-Capivari-Jundiaí (PCJ) in Sao Paulo state (Brazil), control the baseflow processes and resilience in the face of streamflow fluctuations in response to anthropogenic activities and climate variation. The results reveal between 40% and 75% contributions of baseflow to total streamflow in basins overlying crystalline and sedimentary aquifers. The basins in PCJ which mostly overly crystalline aquifers, have shorter water residence times and greater dependence on surface water. Therefore, streamflow in the PCJ basins is vulnerable during the drought period and the management model affected the water resilience of the basins (transfer of water to Cantareira System). The TJ basins have greater streamflow contributions from aquifer discharge linked to the presence of important sedimentary aquifers, which improves resilience under changing rainfall patterns, these basins present a more stable situation of resilience. Ultimately, the two management units require different planning strategies with adaptive and dynamic actions to mitigate the social, economic, and environmental effects caused by the variability and reduction of water sources. Key points Assessment of the role hydrogeological framework in the baseflow and its impact on basin water security. Water management challenges faced to intense anthropological actions and changes in rainfall behaviour, case of tropical basins in metropolitan regions.
人口稠密地区的气候和水需求变化日益影响水文系统，进而影响社会经济条件。在本案例研究中，我们确定了巴西圣保罗州(Sao Paulo state)的两个水资源管理单元Tietê-Jacaré (TJ)和Piracicaba-Capivari-Jundiaí (PCJ)的水文地质框架如何在面对人为活动和气候变化引起的流量波动时控制基流过程和恢复力。结果表明，在结晶和沉积含水层上覆的盆地中，基流对总流量的贡献在40%到75%之间。PCJ盆地大部分为过结晶含水层，水停留时间较短，对地表水的依赖性较大。因此，干旱期PCJ流域的水流是脆弱的，管理模式影响了流域的水恢复力(向Cantareira系统调水)。由于具有重要的沉积含水层，TJ流域的含水层流量贡献更大，在降雨模式变化的条件下，该流域的恢复能力增强，呈现出更稳定的恢复态势。最终，这两个管理单位需要不同的规划策略和适应性和动态行动，以减轻由水资源的变化和减少引起的社会、经济和环境影响。水文地质框架在基流中的作用评价及其对流域水安全的影响。水资源管理面临着激烈的人类学行动和降雨行为变化的挑战，以大都市地区的热带盆地为例。
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