Drafts by Nikhom Chaiwongsaen
The Lower Ping River downstream from the Bhumibol Dam has suffered from the excessive sedimentati... more The Lower Ping River downstream from the Bhumibol Dam has suffered from the excessive sedimentation. The rapid growth of sandbars occurs along the 129 km of the downstream reach within the succession of weir. However, within this succession of weir severe riverbank collapses can also occur locally as rapid growth of sandbars makes the river narrower which in turn increase its flow velocity and power. The objective of this research is to assess riverbank accretion and erosion using remote sensing and GIS techniques. Comparison of satellite images from 2007 and 2017 shows that the total emerged sandbar area increases up to 5,702,557 m 2. The total area of riverbank erosion is 1,150,943 m 2 and the total area of accretion is over 10,561,530 m 2. Digital Shoreline Analysis System (DSAS) software is also used to determine the rate of changes of riverbank erosion and accretion. The DSAS output locates significant changes of river accretion and erosion along the riverbanks with the average rate of erosion at 1.24 m/year and the average rate of accretion at 4.89 m/year between 2007 and 2017. The rapid growth of sandbars along the river reach is responsible for the shallowing and narrowing of river embankment leading to rapid overflow during flooding. The result from this study enables all authorities and stakeholders to recognize the specific location, which severely affected by riverbank accretion and erosion as well as to locate the areas experienced rapid growth of sandbar and huge river channel shifting. There are several possibility implications from this study involving construction of weir, riverbank collapse prevention, and management of intense in-channel sand mining along this river.
The Integrated GPR-Electrical Resistivity Survey (IGRS) technique has revealed the internal struc... more The Integrated GPR-Electrical Resistivity Survey (IGRS) technique has revealed the internal structure and determined the thickness of a sandbar on the Lower Ping River, Changwat Kamphaeng Phet. From the surveys, we recognized five stratigraphic units and several intervening unconformities and scour surfaces. Unit 1 the Mudstone bedrock which can be easily distinguished from sandbar sedimentary bodies due to significantly low electrical resistivity values than the overlying sandbar bodies. Unit 2 Clayey sand sheet; This unit contributes to about one third of the profiles with parallel reflection surface with medium electrical resistivity value averagely 1,000 Ohm-m. Unit 3 Sand-gravel sheet which are parallel planar reflections similar to the Unit 2, but with scatter rougher of upper surface than Unit 2. The unit is considered having the strongest reflection signal and highest electrical resistivity value up to 10,000 Ohm-m. Unit 4 Sand dominate channel fill; This sand dominate channel is always bounded by scour surface showing inclination pattern with the electrical resistivity value around 1,000s Ohm-m. They were interpreted as lateral migration process on point bars of the main channel flow. Unite 5 Clayey sand channel fill; This unit has similar reflection features as the Unit 5, but has much lower electrical resistivity value of the value around 100s Ohm-m. It represents the deposition of lower energy along of this river which is the secondary channel or abandoned channel of the river. IGRS profiles are very useful in detect sand bar thickness. In this study, the IGRS with GPR 500 MHz can detect channel fills at the top of the section which may represent a flood deposit from 2011. This study demonstrates the utility of IGRS for non-destructive investigation of sandbar structure, thickness and the stratigraphic record of flood events in the Central Plain of Thailand.
The Chao Phraya River flows in the largest river basin of Thailand and represents one of the impo... more The Chao Phraya River flows in the largest river basin of Thailand and represents one of the important agricultural and industrial areas in Southeast Asia. The Ping River is one major upstream branch flowing down slope southwardly, joining the Chao Phraya River in the low-lying central plain and ending its course at the Gulf of Thailand. Surprisingly, the overflow occurs frequently and rapidly at the Lower Ping River where channel slope is high, and in particular area, sand-choked is extensively observed, even in normal rainfall condition. In contrary, at the downstream part, the erosion of river bank and shoreline around the mouth of Chao Phraya River has been spatially increasing in place where there should be a massive sediment supply to form a delta. Here we use Landsat imageries taken in 1987, 1997, 2007 and 2017 to analyze geomorphological changes of rivers. Results show that both rivers have undergone the rapid decreasing of water storage capacity and increasing of sand bar areas in river embayment. The total emerged sand bar area in the Lower Ping River increases from 1987 to 2017 up to 28.8 km 2. The excessive trapped bed sediments deposition along the upper reaches is responsible for the shallower of river embankment leading to rapid overflow during flooding. At the Chao Phraya River mouth, a total of 18.8 km 2 of the coastal area has been eroded from 1987 to 2017.This is caused by the reducing of sediment supply leading to non-equilibrium in the deltaic zone of the upper Gulf of Thailand. There are several possibility implications from this study involving construction of weir, in-channel sand mining, reservoir sedimentation and coastal erosion management.
The Ping and Chao Phraya Rivers provide the largest and the most important river basin in Thailan... more The Ping and Chao Phraya Rivers provide the largest and the most important river basin in Thailand. In the past decades, the rivers have been dynamically changed along their courses. At present, shallow sand-choked in the Ping River downstream from the Lower Mae Ping Dam causes flooding repeatedly. In contrary, downstream, the erosion of river banks and shoreline around the Chao Phraya Delta has become an obvious issue instead. The application of an integrated approach of Remote Sensing and GIS techniq ue is one of the most effective ways to detect and assess geomorphological changes over a vast area of the Ping and Chao Phraya River. Four historical river and shoreline dynamics from a 30-year period with one decade interval derived from Landsat imageries obtained in 1987, 1997, 2007, and 2017 show that the Ping and Chao Phraya Rivers have undergone significant changes in their geomorphology. The most obvious and devastating geomorphological changes are the decreasing of the river area and increasing sandbar area of the Ping River. Especially, the river reaches downstream from the Lower Mae Ping Dam and between the succession of weirs along the Ping River, where the inordinate sand budget has been supplied to the river from surrounding granite terrains. The total incr easing sandbar area within the Ping River from the 30-year period of this study is approximately 28.8 km 2. Both geologic conditions and anthropogenic activities are the main factors that responsible for these changes. Whereas the upstream reaches showing the ex cessive deposition of sandbars, the downstream reaches of the Chao Phraya River and the coastal area around its delta have experienced the significant erosion. Approximately 18.8 km 2 of the coastal area has been eroded from 1987 to 2017. It can be assumed that the excessive trapped bedload sediment along the upper reaches may be responsible for this significant erosion of the lower reaches and the coastal area around the delta.
ABTRACT River shallowing due to excessive bedload sediment in the Ping River enhance flooding pot... more ABTRACT River shallowing due to excessive bedload sediment in the Ping River enhance flooding potential in rainy season. Further downstream, erosion/collapsing the Chao Phraya River's bank has become an issue instead. These changes somehow seem to be influenced by water regulation projects along the rivers. Elsewhere, effects of river regulation on the hydraulic regime and sediment transport capacity have been widely studied. The framework of these studies basically evolves around the concept of effects of the baselevel rise and fall. Baselevel is the lowest level to which erosion by river can proceed down into the river bed. Typically, sea level is the baselevel. However, river regulations such as damming will change the river's baselevel. Both upstream and downstream reaches from dam will be affected differently due to the pre-dam conditions. Basically, a regulated river will adjust itself by changing its morphological parameters into the previous equilibrium stage. When a river is dammed, water discharge and sediment load are the main altered parameters that dam input to the downstream reach. Combining three pre-dam conditions of a river (aggradation, equilibrium, and degradation) with the other 2 variables, water discharge and sediment supply, which altered by dam yields 27 probabilities of possible responses to change. This proposed conceptual model will be used as a foundation of the study of the effects of river regulation on the Ping and Chao Phraya Rivers. The total length of the Ping and the Chao Phraya combined is over 1,000 km. The geological conditions, gradient, and intensity of river regulation have changes throughout their courses. In order to study the effects of river regulation on the Ping and Chao Phraya Rivers effectively, they are preliminarily divided into seven reaches according to the similarity of their conditions. These reaches had their own different conditions before the river regulations have been introduced, and they have responded differently to adjust to their equilibrium. The objective of the classification model presented here is to simplify the study of river responding trend after regulated. By using this classification format, both effects on upstream and downstream of dam and reservoir can be categorized and predicted. Hopefully, this classification system can be used as a foundation for any study of the effects of river regulation elsewhere as well.
Papers by Nikhom Chaiwongsaen
Open Geosciences, 2019
The Chao Phraya River flows in the largest river basin of Thailand and represents one of the impo... more The Chao Phraya River flows in the largest river basin of Thailand and represents one of the important agricultural and industrial areas in Southeast Asia. The Ping River is one major upstream branch flowing down slope southwardly, joining the Chao Phraya River in the low-lying central plain and ending its course at the Gulf of Thailand. Surprisingly, the overflow occurs frequently and rapidly at the Lower Ping River where channel slope is high, and in particular area, sand-choked is extensively observed, even in normal rainfall condition. In contrary, at the downstream part, the erosion of river bank and shoreline around the mouth of Chao Phraya River has been spatially increasing in place where there should be a massive sediment supply to form a delta. Here we use Landsat imageries taken in 1987, 1997, 2007 and 2017 to analyze geomorphological changes of rivers. Results show that both rivers have undergone the rapid decreasing of water storage capacity and increasing of sand bar a...
Frontiers in Ecology and Evolution, 2021
Sedimentary evidence of storms and fluvial floods (FFs) is crucial for a better understanding of ... more Sedimentary evidence of storms and fluvial floods (FFs) is crucial for a better understanding of such events in coastal zones. In this study, we analyzed the sedimentary characteristics of the coastal storm and FF deposits at the Hoa Duan barrier, Thua Thien Hue, central Vietnam. Analyses of the sedimentary structures and properties (grain size distribution, composition, roundness, and sphericity) and loss on ignition revealed that the storm sediments were comprised of coarser grains with a low organic and carbonated content, and with sedimentary structures, including parallel and inclined landward lamination, multiple sets of normal and reverse grading, mud rip-up clasts, and sharp and erosional contacts (both top and bottom) with finer-grain layers. Conversely, the FF sediments had only fine to very fine grains, with dominant high organic and carbonate contents, and only exhibited sedimentary structures of sharp erosional top and bottom contacts with coarser-grained layers. The cl...
Open Geosci., 2019
The Chao Phraya River fl ows in the largest river
basin of Thailand and represents one of the im... more The Chao Phraya River fl ows in the largest river
basin of Thailand and represents one of the important
agricultural and industrial areas in Southeast Asia. The
Ping River is one major upstream branch fl owing down
slope southwardly, joining the Chao Phraya River in the
low-lying central plain and ending its course at the Gulf
of Thailand. Surprisingly, the overfl ow occurs frequently
and rapidly at the Lower Ping River where channel slope
is high, and in particular area, sand-choked is extensively
observed, even in normal rainfall condition. In contrary, at
the downstream part, the erosion of river bank and shore-
line around the mouth of Chao Phraya River has been spa-
tially increasing in place where there should be a massive
sediment supply to form a delta. Here we use Landsat im-
ageries taken in 1987, 1997, 2007 and 2017 to analyze geo-
morphological changes of rivers. Results show that both
rivers have undergone the rapid decreasing of water stor-
age capacity and increasing of sand bar areas in river em-
bayment. The total emerged sand bar area in the Lower
Ping River increases from 1987 to 2017 up to 28.8 km
2
. The
excessive trapped bed sediments deposition along the up-
per reaches is responsible for the shallower of river em-
bankment leading to rapid overfl ow during fl ooding.At
the Chao Phraya River mouth, a total of 18.8 km
2
of the
coastal area has been eroded from 1987 to 2017.This is
caused by the reducing of sediment supply leading to non-
equilibrium in the deltaic zone of the upper Gulf of Thai-
land. There are several possibility implications from this
study involving construction of weir, in-channel sand min-
ing, reservoir sedimentation and coastal erosion manage-
ment.
Keywords: Lower Ping and Chao Phraya Rivers; Landsat
imagery; river geomorphology; river regulation; sand bar
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Drafts by Nikhom Chaiwongsaen
Papers by Nikhom Chaiwongsaen
basin of Thailand and represents one of the important
agricultural and industrial areas in Southeast Asia. The
Ping River is one major upstream branch fl owing down
slope southwardly, joining the Chao Phraya River in the
low-lying central plain and ending its course at the Gulf
of Thailand. Surprisingly, the overfl ow occurs frequently
and rapidly at the Lower Ping River where channel slope
is high, and in particular area, sand-choked is extensively
observed, even in normal rainfall condition. In contrary, at
the downstream part, the erosion of river bank and shore-
line around the mouth of Chao Phraya River has been spa-
tially increasing in place where there should be a massive
sediment supply to form a delta. Here we use Landsat im-
ageries taken in 1987, 1997, 2007 and 2017 to analyze geo-
morphological changes of rivers. Results show that both
rivers have undergone the rapid decreasing of water stor-
age capacity and increasing of sand bar areas in river em-
bayment. The total emerged sand bar area in the Lower
Ping River increases from 1987 to 2017 up to 28.8 km
2
. The
excessive trapped bed sediments deposition along the up-
per reaches is responsible for the shallower of river em-
bankment leading to rapid overfl ow during fl ooding.At
the Chao Phraya River mouth, a total of 18.8 km
2
of the
coastal area has been eroded from 1987 to 2017.This is
caused by the reducing of sediment supply leading to non-
equilibrium in the deltaic zone of the upper Gulf of Thai-
land. There are several possibility implications from this
study involving construction of weir, in-channel sand min-
ing, reservoir sedimentation and coastal erosion manage-
ment.
Keywords: Lower Ping and Chao Phraya Rivers; Landsat
imagery; river geomorphology; river regulation; sand bar
basin of Thailand and represents one of the important
agricultural and industrial areas in Southeast Asia. The
Ping River is one major upstream branch fl owing down
slope southwardly, joining the Chao Phraya River in the
low-lying central plain and ending its course at the Gulf
of Thailand. Surprisingly, the overfl ow occurs frequently
and rapidly at the Lower Ping River where channel slope
is high, and in particular area, sand-choked is extensively
observed, even in normal rainfall condition. In contrary, at
the downstream part, the erosion of river bank and shore-
line around the mouth of Chao Phraya River has been spa-
tially increasing in place where there should be a massive
sediment supply to form a delta. Here we use Landsat im-
ageries taken in 1987, 1997, 2007 and 2017 to analyze geo-
morphological changes of rivers. Results show that both
rivers have undergone the rapid decreasing of water stor-
age capacity and increasing of sand bar areas in river em-
bayment. The total emerged sand bar area in the Lower
Ping River increases from 1987 to 2017 up to 28.8 km
2
. The
excessive trapped bed sediments deposition along the up-
per reaches is responsible for the shallower of river em-
bankment leading to rapid overfl ow during fl ooding.At
the Chao Phraya River mouth, a total of 18.8 km
2
of the
coastal area has been eroded from 1987 to 2017.This is
caused by the reducing of sediment supply leading to non-
equilibrium in the deltaic zone of the upper Gulf of Thai-
land. There are several possibility implications from this
study involving construction of weir, in-channel sand min-
ing, reservoir sedimentation and coastal erosion manage-
ment.
Keywords: Lower Ping and Chao Phraya Rivers; Landsat
imagery; river geomorphology; river regulation; sand bar