Abstract Frequent floods around the globe including recent events in several states in Malaysia h... more Abstract Frequent floods around the globe including recent events in several states in Malaysia have damaged the residential properties, infrastructures and crops or even deaths. Clearing vegetation or trees on the floodplain has been pointed out as a contributing factor to the damages. Thus, the influence of floodplain vegetation on the river hydraulics during flooding must be better understood. The hydraulics of flood flows in non-erodible vegetated meandering channel was experimented in the laboratory where two-lined steel rods were installed along a riparian zone to simulate as trees. The stage-discharge relationship, flow resistance, depth-averaged velocity, streamwise vorticity and boundary shear stress patterns during shallow and deep flood inundations were studied. The findings showed that floodplain vegetation had increased the channel flow depth by 32% and its flow resistance. The velocity in vegetated zone was lowered and the shear stress reduced by 86.5% to 91% along the river meander. In addition, the trees also limit flow interaction between main channel and floodplain. Abstrak Kejadian banjir di seluruh dunia termasuklah di beberapa negeri di Malaysia telah memusnahkan harta benda kediaman, infrastruktur, tanam-tanaman dan juga kehilangan nyawa. Penebangan pokok di dataran banjir telah menyumbangkan kepada tahap kemusnahan tersebut. Oleh itu, adalah penting untuk memahami kesan kehadiran pokok-pokok tersebut terhadap hidraulik sungai ketika banjir. Satu kajian makmal ke atas sistem sungai berliku telah dijalankan. Dua barisan rod besi yang digunakan sebagai pokok-pokok telah disusun di atas dataran banjir di sepanjang sungai. Hubungan aras air-kadaralir, rintangan aliran, corak halaju-halaju primer dan sekunder dan tegasan ricih ketika banjir telah dikaji. Hasil kajian telah menunjukkan bahawa kehadiran pokok-pokok tersebut telah meningkatkan kedalaman aliran sebanyak 32% dan juga rintangan aliran. Halaju aliran telah berkurang dan tegasan ricih jugan menurun di antara 86.5% dan 91%. Pokok-pokok juga telah menghadkan aliran di antara saluran utaman dan dataran banjir. Kata kunci: Permodelan fizikal; eksperimen makmal, saluran berliku, pokok dataran banjir, hidraulik banjir
Abstract Floods are the most common natural disasters in Malaysia and have damaged structures, i... more Abstract Floods are the most common natural disasters in Malaysia and have damaged structures, infrastructures, crops and even causes fatalities. It may also lead to erosion and sedimentation in rivers and this will result to complex river behaviour. A hydraulic laboratory experimental study was carried out. Also, flood flow and sediment transport in straight compound channels involving flow resistance, distribution of depth-averaged velocity, stream-wise vorticity patterns, channel bed morphology and bed load transport rate in non-vegetated compound straight mobile bed channels were investigated. The finding showed that the Darcy Weisbach friction factor f increased by 40% and 54% for floodplain and main channel, respectively when relative flood flow depth increase from 0.30 to 0.50. The small bed load transport rates of 0.09 g/s and 0.03 g/s for shallow and deep overbank flows, respectively were measured due to effect of very gentle or mild channel bed slope which was fixed at a gradient of 0.1%. Abstrak Banjir merupakan bencana alam yang paling biasa berlaku di Malaysia dan telah merosakan struktur, infrastruktur, tanaman dan juga menyebabkan kematian. Ia juga boleh membawa kepada hakisan dan pemendapan di sungai dan menjadikan aliran sungai menjadi lebih kompleks. Kajian ekperimen hidraulik dijalankan di makmal. Juga, aliran banjir dan pengangkutan sedimen di saluran kompaun lurus tanpa tumbuhan melibatkan pekali kekasaran, taburan halaju aliran, arus sekunder dan pembentukan dasar telah dikaji. Hasil kajian menunjukkan bahawa factor geseran Darcy Weisbach f meningkat sebanyak 40% dan 54% pada dataran banjir dan saluran utama dengan kenaikan relative kedalaman aliran banjir dari 0.30 kepada 0.50. Kadar pengangkutan sedimen yang kecil iaitu 0.09 g/s untuk aliran cetek dan 0.03 g/s untuk aliran dalam kerana kesan kecerunan terlalu mendatar yang telah ditetapkan pada kecerunan 0.1%. Kata kunci: Saluran majmuk lurus; pekali kekasaran; taburan halaju aliran; morfologi permukaan dasar
Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespre... more Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespread damages to buildings, crops and infrastructure. Effort to understanding on this phenomenon is an interesting research. The objectives of this study are to determine the stage-discharge relationship, roughness coefficient and streamwise velocity distribution in a vegetated straight compound channel. The effects of two-line emergent vegetation along the edge of floodplain are studied by using a flume in the Hydraulics Laboratory, Faculty of Civil Engineering, Universiti Teknologi Malaysia (UTM). The results on stage-discharge relationship, Manning’s n and velocity distribution for overbank flows are presented in this paper. From the analysis, it is found that the vegetation influences stage-discharge where retardation of flow takes place. The maximum velocity zone is observed to be in the main channel and less fluid momentum transfer takes place in the presence of vegetation. Vegetated floodplain also influence the increases of channel roughness.
Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespre... more Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespread damages to buildings, crops and infrastructure. Effort to understanding on this phenomenon is an interesting research. The objectives of this study are to determine the stage-discharge relationship, roughness coefficient and streamwise velocity distribution in a vegetated straight compound channel. The effects of two-line emergent vegetation along the edge of floodplain are studied by using a flume in the Hydraulics Laboratory, Faculty of Civil Engineering, Universiti Teknologi Malaysia (UTM). The results on stage-discharge relationship, Manning’s n and velocity distribution for overbank flows are presented in this paper. From the analysis, it is found that the vegetation influences stage-discharge where retardation of flow takes place. The maximum velocity zone is observed to be in the main channel and less fluid momentum transfer takes place in the presence of vegetation. Vegetated floodplain also influence the increases of channel roughness.
Floods hit various states in Malaysia and caused damage to properties, infrastructures, human suf... more Floods hit various states in Malaysia and caused damage to properties, infrastructures, human suffering and even loss of lives. Frequent flood incidents and soil erosion are reported which lead to sedimentation problems in the drainage and river systems due to urbanisation. It is important to understand the sedimentation process and the behaviour of bed forms in the water course for post-flood events. However, it is risky and dangerous to conduct field study during occurrence of flooding. Laboratory study has been chosen as an alternative to fulfill the objectives. Experimental investigations on the bed load transport and bed forms in rectangular open channels have been undertaken. Small and large scale physical models are used in the laboratory. The effects of flow on mobile sandy bed channel and bed load transportation are studied by using a modified flumes with an asymmetric straight compound channel. However, the findings on rate of transport and bed formation for non-flooding cases are presented in this paper. It is found that the bed formation profiles for both channels are different due to scale and flume characteristics. The bed forms, erosion and deposition processes are significantly influenced by the water velocity in the channel. The bed forms observed for large flume are repeating ripples and dunes; meanwhile variable of ripples are observed in small flume.
Researches on compound channel hydraulics have been carried out for many years, yet few are
conc... more Researches on compound channel hydraulics have been carried out for many years, yet few are
concerned with sediment transport. In order to prevent sediment problem, the sediment transport process and
the influence of bed form on the roughness of the river flows must be understood. An experimental
investigation on the flood flow characteristics and sediment transport in straight compound channel have been
undertaken. The effects of mobile-bed channels on flow characteristics and sediment transport were studied
by using flumes in the Hydraulics and Hydrology Laboratory, Faculty of Civil Engineering, UniversitiTeknologi
Malaysia (UTM). The flume is 4.0 m long, 0.6 m wide and configured into a 0.3 m wide and 0.05 m depth of
rectangular main channel with a single floodplain. A mobile-bed channel is composed of uniform graded sand
with a d of 0.8 mm. The findings on sediment transport rateand b 50 ed formation of the bed channel for overbank
flows in straight rectangular compound channels are presented in this paper. It has been found that the
maximum velocity zone is observed to be in the main channel where sediment transportation takes place. Thus,
the bed formation change after the sedimentation and erosion occur at the channel bed which is also influenced
by the higher velocity in the main channel.
Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespre... more Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespread damages to buildings, crops and infrastructure. Effort to understanding on this phenomenon is an interesting research. The objectives of this study are to determine the stage-discharge relationship, roughness coefficient and streamwise velocity distribution in a vegetated straight compound channel. The effects of two-line emergent vegetation along the edge of floodplain are studied by using a flume in the Hydraulics Laboratory, Faculty of Civil Engineering, Universiti Teknologi Malaysia (UTM). The results on stage-discharge relationship, Manning’s n and velocity distribution for overbank flows are presented in this paper. From the analysis, it is found that the vegetation influences stage-discharge where retardation of flow takes place. The maximum velocity zone is observed to be in the main channel and less fluid momentum transfer takes place in the presence of vegetation. Vegetated floodplain also influence the increases of channel roughness.
Abstract Frequent floods around the globe including recent events in several states in Malaysia h... more Abstract Frequent floods around the globe including recent events in several states in Malaysia have damaged the residential properties, infrastructures and crops or even deaths. Clearing vegetation or trees on the floodplain has been pointed out as a contributing factor to the damages. Thus, the influence of floodplain vegetation on the river hydraulics during flooding must be better understood. The hydraulics of flood flows in non-erodible vegetated meandering channel was experimented in the laboratory where two-lined steel rods were installed along a riparian zone to simulate as trees. The stage-discharge relationship, flow resistance, depth-averaged velocity, streamwise vorticity and boundary shear stress patterns during shallow and deep flood inundations were studied. The findings showed that floodplain vegetation had increased the channel flow depth by 32% and its flow resistance. The velocity in vegetated zone was lowered and the shear stress reduced by 86.5% to 91% along the river meander. In addition, the trees also limit flow interaction between main channel and floodplain. Abstrak Kejadian banjir di seluruh dunia termasuklah di beberapa negeri di Malaysia telah memusnahkan harta benda kediaman, infrastruktur, tanam-tanaman dan juga kehilangan nyawa. Penebangan pokok di dataran banjir telah menyumbangkan kepada tahap kemusnahan tersebut. Oleh itu, adalah penting untuk memahami kesan kehadiran pokok-pokok tersebut terhadap hidraulik sungai ketika banjir. Satu kajian makmal ke atas sistem sungai berliku telah dijalankan. Dua barisan rod besi yang digunakan sebagai pokok-pokok telah disusun di atas dataran banjir di sepanjang sungai. Hubungan aras air-kadaralir, rintangan aliran, corak halaju-halaju primer dan sekunder dan tegasan ricih ketika banjir telah dikaji. Hasil kajian telah menunjukkan bahawa kehadiran pokok-pokok tersebut telah meningkatkan kedalaman aliran sebanyak 32% dan juga rintangan aliran. Halaju aliran telah berkurang dan tegasan ricih jugan menurun di antara 86.5% dan 91%. Pokok-pokok juga telah menghadkan aliran di antara saluran utaman dan dataran banjir. Kata kunci: Permodelan fizikal; eksperimen makmal, saluran berliku, pokok dataran banjir, hidraulik banjir
Abstract Floods are the most common natural disasters in Malaysia and have damaged structures, i... more Abstract Floods are the most common natural disasters in Malaysia and have damaged structures, infrastructures, crops and even causes fatalities. It may also lead to erosion and sedimentation in rivers and this will result to complex river behaviour. A hydraulic laboratory experimental study was carried out. Also, flood flow and sediment transport in straight compound channels involving flow resistance, distribution of depth-averaged velocity, stream-wise vorticity patterns, channel bed morphology and bed load transport rate in non-vegetated compound straight mobile bed channels were investigated. The finding showed that the Darcy Weisbach friction factor f increased by 40% and 54% for floodplain and main channel, respectively when relative flood flow depth increase from 0.30 to 0.50. The small bed load transport rates of 0.09 g/s and 0.03 g/s for shallow and deep overbank flows, respectively were measured due to effect of very gentle or mild channel bed slope which was fixed at a gradient of 0.1%. Abstrak Banjir merupakan bencana alam yang paling biasa berlaku di Malaysia dan telah merosakan struktur, infrastruktur, tanaman dan juga menyebabkan kematian. Ia juga boleh membawa kepada hakisan dan pemendapan di sungai dan menjadikan aliran sungai menjadi lebih kompleks. Kajian ekperimen hidraulik dijalankan di makmal. Juga, aliran banjir dan pengangkutan sedimen di saluran kompaun lurus tanpa tumbuhan melibatkan pekali kekasaran, taburan halaju aliran, arus sekunder dan pembentukan dasar telah dikaji. Hasil kajian menunjukkan bahawa factor geseran Darcy Weisbach f meningkat sebanyak 40% dan 54% pada dataran banjir dan saluran utama dengan kenaikan relative kedalaman aliran banjir dari 0.30 kepada 0.50. Kadar pengangkutan sedimen yang kecil iaitu 0.09 g/s untuk aliran cetek dan 0.03 g/s untuk aliran dalam kerana kesan kecerunan terlalu mendatar yang telah ditetapkan pada kecerunan 0.1%. Kata kunci: Saluran majmuk lurus; pekali kekasaran; taburan halaju aliran; morfologi permukaan dasar
Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespre... more Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespread damages to buildings, crops and infrastructure. Effort to understanding on this phenomenon is an interesting research. The objectives of this study are to determine the stage-discharge relationship, roughness coefficient and streamwise velocity distribution in a vegetated straight compound channel. The effects of two-line emergent vegetation along the edge of floodplain are studied by using a flume in the Hydraulics Laboratory, Faculty of Civil Engineering, Universiti Teknologi Malaysia (UTM). The results on stage-discharge relationship, Manning’s n and velocity distribution for overbank flows are presented in this paper. From the analysis, it is found that the vegetation influences stage-discharge where retardation of flow takes place. The maximum velocity zone is observed to be in the main channel and less fluid momentum transfer takes place in the presence of vegetation. Vegetated floodplain also influence the increases of channel roughness.
Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespre... more Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespread damages to buildings, crops and infrastructure. Effort to understanding on this phenomenon is an interesting research. The objectives of this study are to determine the stage-discharge relationship, roughness coefficient and streamwise velocity distribution in a vegetated straight compound channel. The effects of two-line emergent vegetation along the edge of floodplain are studied by using a flume in the Hydraulics Laboratory, Faculty of Civil Engineering, Universiti Teknologi Malaysia (UTM). The results on stage-discharge relationship, Manning’s n and velocity distribution for overbank flows are presented in this paper. From the analysis, it is found that the vegetation influences stage-discharge where retardation of flow takes place. The maximum velocity zone is observed to be in the main channel and less fluid momentum transfer takes place in the presence of vegetation. Vegetated floodplain also influence the increases of channel roughness.
Floods hit various states in Malaysia and caused damage to properties, infrastructures, human suf... more Floods hit various states in Malaysia and caused damage to properties, infrastructures, human suffering and even loss of lives. Frequent flood incidents and soil erosion are reported which lead to sedimentation problems in the drainage and river systems due to urbanisation. It is important to understand the sedimentation process and the behaviour of bed forms in the water course for post-flood events. However, it is risky and dangerous to conduct field study during occurrence of flooding. Laboratory study has been chosen as an alternative to fulfill the objectives. Experimental investigations on the bed load transport and bed forms in rectangular open channels have been undertaken. Small and large scale physical models are used in the laboratory. The effects of flow on mobile sandy bed channel and bed load transportation are studied by using a modified flumes with an asymmetric straight compound channel. However, the findings on rate of transport and bed formation for non-flooding cases are presented in this paper. It is found that the bed formation profiles for both channels are different due to scale and flume characteristics. The bed forms, erosion and deposition processes are significantly influenced by the water velocity in the channel. The bed forms observed for large flume are repeating ripples and dunes; meanwhile variable of ripples are observed in small flume.
Researches on compound channel hydraulics have been carried out for many years, yet few are
conc... more Researches on compound channel hydraulics have been carried out for many years, yet few are
concerned with sediment transport. In order to prevent sediment problem, the sediment transport process and
the influence of bed form on the roughness of the river flows must be understood. An experimental
investigation on the flood flow characteristics and sediment transport in straight compound channel have been
undertaken. The effects of mobile-bed channels on flow characteristics and sediment transport were studied
by using flumes in the Hydraulics and Hydrology Laboratory, Faculty of Civil Engineering, UniversitiTeknologi
Malaysia (UTM). The flume is 4.0 m long, 0.6 m wide and configured into a 0.3 m wide and 0.05 m depth of
rectangular main channel with a single floodplain. A mobile-bed channel is composed of uniform graded sand
with a d of 0.8 mm. The findings on sediment transport rateand b 50 ed formation of the bed channel for overbank
flows in straight rectangular compound channels are presented in this paper. It has been found that the
maximum velocity zone is observed to be in the main channel where sediment transportation takes place. Thus,
the bed formation change after the sedimentation and erosion occur at the channel bed which is also influenced
by the higher velocity in the main channel.
Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespre... more Floods are frequent events occur in Malaysia and cause loss of life, human suffering and widespread damages to buildings, crops and infrastructure. Effort to understanding on this phenomenon is an interesting research. The objectives of this study are to determine the stage-discharge relationship, roughness coefficient and streamwise velocity distribution in a vegetated straight compound channel. The effects of two-line emergent vegetation along the edge of floodplain are studied by using a flume in the Hydraulics Laboratory, Faculty of Civil Engineering, Universiti Teknologi Malaysia (UTM). The results on stage-discharge relationship, Manning’s n and velocity distribution for overbank flows are presented in this paper. From the analysis, it is found that the vegetation influences stage-discharge where retardation of flow takes place. The maximum velocity zone is observed to be in the main channel and less fluid momentum transfer takes place in the presence of vegetation. Vegetated floodplain also influence the increases of channel roughness.
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Papers by mazlin jumain
concerned with sediment transport. In order to prevent sediment problem, the sediment transport process and
the influence of bed form on the roughness of the river flows must be understood. An experimental
investigation on the flood flow characteristics and sediment transport in straight compound channel have been
undertaken. The effects of mobile-bed channels on flow characteristics and sediment transport were studied
by using flumes in the Hydraulics and Hydrology Laboratory, Faculty of Civil Engineering, UniversitiTeknologi
Malaysia (UTM). The flume is 4.0 m long, 0.6 m wide and configured into a 0.3 m wide and 0.05 m depth of
rectangular main channel with a single floodplain. A mobile-bed channel is composed of uniform graded sand
with a d of 0.8 mm. The findings on sediment transport rateand b 50 ed formation of the bed channel for overbank
flows in straight rectangular compound channels are presented in this paper. It has been found that the
maximum velocity zone is observed to be in the main channel where sediment transportation takes place. Thus,
the bed formation change after the sedimentation and erosion occur at the channel bed which is also influenced
by the higher velocity in the main channel.
concerned with sediment transport. In order to prevent sediment problem, the sediment transport process and
the influence of bed form on the roughness of the river flows must be understood. An experimental
investigation on the flood flow characteristics and sediment transport in straight compound channel have been
undertaken. The effects of mobile-bed channels on flow characteristics and sediment transport were studied
by using flumes in the Hydraulics and Hydrology Laboratory, Faculty of Civil Engineering, UniversitiTeknologi
Malaysia (UTM). The flume is 4.0 m long, 0.6 m wide and configured into a 0.3 m wide and 0.05 m depth of
rectangular main channel with a single floodplain. A mobile-bed channel is composed of uniform graded sand
with a d of 0.8 mm. The findings on sediment transport rateand b 50 ed formation of the bed channel for overbank
flows in straight rectangular compound channels are presented in this paper. It has been found that the
maximum velocity zone is observed to be in the main channel where sediment transportation takes place. Thus,
the bed formation change after the sedimentation and erosion occur at the channel bed which is also influenced
by the higher velocity in the main channel.