Yeochari tidal flat
Yeochari tidal flat is located in the south of Ganghwa Island, northern Gyeonggi Bay. The flat lacks fluvial drainage system and extensive marshes. Small drainage channels in the upper to middle intertidal flat widen exponentially in the lower intertidal zone where they merge to form complicated channel and interchannel bar morphology.
Tidal flat stretches southwestward as much as 6.5 km during spring low tides. It is morphologically divided into three parts, upper intertidal flat with little marsh, middle intertidal flat with little tidal creeks, and lower intertidal flat with large tidal channels.
Channels in the lower intertidal flat are 200-600 m wide and 1-2.5 m deep at bankful stage. They are actively migrating in response to varying degree of tidal currents and rain-induced runoff discharge. Pronounced channel migration occurred during summertime rainy season when point bar migrated as fast as 40 m per month. In contrast, channel migration rate during wintertime is dramatically reduced down to less than 1 m per month.
Figure 1. Simple dunes in the lower intertidal flat of Yeochari tidal flat.
Jujin channel tidal flat
Gomso Bay is a semi-enclosed, bedrock-confined macrotidal embayment with a wide entrance to the west. Gomso Bay has a typical funnel-shaped geometry with two channels emptying into the bay. Of particular interest is Jujin Channel Estuary that adjoins the bay in the south, which merges into a large main channel running east and west in the northern part of the bay. The bankful water depth of Jujin Channel is less than 3 m, which is in contrast to the main channel with water depth over 20 m during spring tides. Southern flanks of the main channel are dominated by an extensive and gentle-sloped tidal flat that is heavily dissected by a dense network of smaller tidal channels.
？Figure 2. Meander bend cutoff in the upper intertidal flat of Jujin Channel tidal flat.
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Sittang River
Sittang River empties into the Gulf of Martaban at the eastern edge of Ayeyarwady delta in Myanmar. The river is about 420 km and its mean annual discharge is around 50 cubic kilometers per year. Sittang River is strongly influenced by monsoon climate. Flooding season starts from May and ends in October, which is followed by dry season. Sittang River is considered to be one of the best modern analogues of reservoirs formed in tidal-fluvial transition such as Athabasca Oil Sands in Alberta, Canada, Jurassic rocks in Norwegian Contiental Shelf, and Miocene rocks in Venezuela. The river has a full suite transitional subenvironments, purely fluvial, tidally influenced fluvially dominated, tidally and fluvially dominated, and fluvially influenced tidally dominated. The river has well-defined, large-scale meander scrolls that are directly comparable to those of McMurray Formation in Alberta, Canada. Our lab did historical field trips in 2014 and 2015 to find field study locations. Full scale field study is under planning and is about to kick off in February 2016.
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Figure 3. Large scro？ll bars on the point bar of sinuous channel near bedload convergence near Setsu, Sittang River, Myanmar (2015.2.10)
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Dicksonfjorden
Dicksonfjorden is located in the one of the northern branches of Isfjorden in Svalbard. Extensive outwash delta plains are developed in the inner reach of Dicksonfjorden. With microtidal range (less than 2 m during spring tides), low slope-gradient of tidal flats, forming most of delta plains, resulted in a 7-8 km long tidal-fluvial transition zone. Prolonged non-flowing conditions of rivers during the most of the year, tidal range, local discharge from alluvial fans developed along the stretch of fjord, and strong wave conditions during summer make tidal flats in the Dicksonfjord unique place to explore sedimentology, morphology, and stratigraphy in an arctic tidal-fluvial transitional environment. Our lab started working on the tidal flats in the Dicksonfjorden in 2016 in close collaboration with Prof. Maria Jensen (UNIS, Norway) to address factors governing temporal and spatial distribution of surface sediments and morphology of channels to develop facies models for arctic tidal flats.
？ Figure 4. Areal view of tidal flats in Dicksonfjorden, Svalbard (2016.7.9). Tidal flats are complicated by sinuous tidal channels. Salt precipitates on the upper intertidal flats are shown in white.
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Yeochari tidal flat is located in the south of Ganghwa Island, northern Gyeonggi Bay. The flat lacks fluvial drainage system and extensive marshes. Small drainage channels in the upper to middle intertidal flat widen exponentially in the lower intertidal zone where they merge to form complicated channel and interchannel bar morphology.
Tidal flat stretches southwestward as much as 6.5 km during spring low tides. It is morphologically divided into three parts, upper intertidal flat with little marsh, middle intertidal flat with little tidal creeks, and lower intertidal flat with large tidal channels.
Channels in the lower intertidal flat are 200-600 m wide and 1-2.5 m deep at bankful stage. They are actively migrating in response to varying degree of tidal currents and rain-induced runoff discharge. Pronounced channel migration occurred during summertime rainy season when point bar migrated as fast as 40 m per month. In contrast, channel migration rate during wintertime is dramatically reduced down to less than 1 m per month.
Figure 1. Simple dunes in the lower intertidal flat of Yeochari tidal flat.
Jujin channel tidal flat
Gomso Bay is a semi-enclosed, bedrock-confined macrotidal embayment with a wide entrance to the west. Gomso Bay has a typical funnel-shaped geometry with two channels emptying into the bay. Of particular interest is Jujin Channel Estuary that adjoins the bay in the south, which merges into a large main channel running east and west in the northern part of the bay. The bankful water depth of Jujin Channel is less than 3 m, which is in contrast to the main channel with water depth over 20 m during spring tides. Southern flanks of the main channel are dominated by an extensive and gentle-sloped tidal flat that is heavily dissected by a dense network of smaller tidal channels.
？Figure 2. Meander bend cutoff in the upper intertidal flat of Jujin Channel tidal flat.
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Sittang River
Sittang River empties into the Gulf of Martaban at the eastern edge of Ayeyarwady delta in Myanmar. The river is about 420 km and its mean annual discharge is around 50 cubic kilometers per year. Sittang River is strongly influenced by monsoon climate. Flooding season starts from May and ends in October, which is followed by dry season. Sittang River is considered to be one of the best modern analogues of reservoirs formed in tidal-fluvial transition such as Athabasca Oil Sands in Alberta, Canada, Jurassic rocks in Norwegian Contiental Shelf, and Miocene rocks in Venezuela. The river has a full suite transitional subenvironments, purely fluvial, tidally influenced fluvially dominated, tidally and fluvially dominated, and fluvially influenced tidally dominated. The river has well-defined, large-scale meander scrolls that are directly comparable to those of McMurray Formation in Alberta, Canada. Our lab did historical field trips in 2014 and 2015 to find field study locations. Full scale field study is under planning and is about to kick off in February 2016.
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Figure 3. Large scro？ll bars on the point bar of sinuous channel near bedload convergence near Setsu, Sittang River, Myanmar (2015.2.10)
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Dicksonfjorden
Dicksonfjorden is located in the one of the northern branches of Isfjorden in Svalbard. Extensive outwash delta plains are developed in the inner reach of Dicksonfjorden. With microtidal range (less than 2 m during spring tides), low slope-gradient of tidal flats, forming most of delta plains, resulted in a 7-8 km long tidal-fluvial transition zone. Prolonged non-flowing conditions of rivers during the most of the year, tidal range, local discharge from alluvial fans developed along the stretch of fjord, and strong wave conditions during summer make tidal flats in the Dicksonfjord unique place to explore sedimentology, morphology, and stratigraphy in an arctic tidal-fluvial transitional environment. Our lab started working on the tidal flats in the Dicksonfjorden in 2016 in close collaboration with Prof. Maria Jensen (UNIS, Norway) to address factors governing temporal and spatial distribution of surface sediments and morphology of channels to develop facies models for arctic tidal flats.
？ Figure 4. Areal view of tidal flats in Dicksonfjorden, Svalbard (2016.7.9). Tidal flats are complicated by sinuous tidal channels. Salt precipitates on the upper intertidal flats are shown in white.
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