Chao Phraya Delta Research Articles

Climate change influences on the streamflow and sediment supply to the Chao Phraya River basin, Thailand

This study investigates the effects of climate change on the sediment loads of the Ping and Wang River basins and their contribution to the sediment dynamics of the lower Chao Phraya River basin in Thailand. The various climate models under different Representative Concentration Pathways (RCPs) scenarios are employed to project sediment loads in future. The findings indicate a significant increase in river flow approximately 20% in the Ping River (PR) and 35% in the Wang River (WR) by the mid-21st century and continuing into the distant future. Consequently, this is expected to result in sediment loads up to 0.33 × 106 t/y in the PR and 0.28 × 106 t/y in the WR. This escalation is particularly notable under the RCP 8.5 scenario, which assumes higher greenhouse gas emissions. Additionally, the research provides insights into the potential positive implications for the Chao Phraya Delta's coastal management. Without further damming in the Ping and Wang River basins, the anticipated rise in sediment supply could aid in mitigating the adverse effects of land subsidence and sea-level rise, which have historically caused extensive shoreline retreat in the delta region, particularly around Bangkok Metropolis. The paper concludes that proactive adaptation strategies are required to manage the expected changes in the hydrological and sediment regimes to protect vulnerable coastal zones and ensure the sustainable management of the Chao Phraya River Basin in the face of climate change.

Can 210Pb be used as a paleo-storm proxy?

There is increasing interest within the scientific community, as well as the public, to determine if tropical cyclones are increasing in frequency and/or magnitude because of climate change. Unfortunately, the instrumental weather record only extends over the last 100–150 years depending upon location. It is thus desirable to develop paleo-storm proxies to extend the tropical cyclone record to hundreds, if not thousands, of years. Overwash sand deposits, sediment grain size, and various geochemical parameters (e.g., δ13C, δ15N, C/N) have been applied successfully for coastal lake sediments. We present here another potential proxy candidate, the natural radionuclide 210Pb. With a 22.2-year half-life, 210Pb age dating is often used to calibrate other proxies over essentially the same period as the instrumental storm record. We hypothesize here that trends in the 210Pb profiles, in addition to providing chronological information, can provide independent records of storm deposits in some situations. To illustrate how 210Pb may serve as an additional storm proxy, we present data from sediment cores collected from the Chao Phraya Delta (Upper Gulf of Thailand), an area characterized by a rapidly retreating shoreline. Some of the 210Pb profiles mark sedimentary layers with anomalously low excess 210Pb activities interspersed between layers with significant excess activities. We suggest that these layers may result from rapid deposition offshore of older storm-eroded shoreline material. The estimated ages of these 210Pb-deficient layers match, within estimated uncertainties, years when typhoons or tropical storms are reported to have severely eroded the nearby Thai coastline. The matching of the time scales of 210Pb and recorded tropical cyclones, both about 100–150 years, allows this approach to be used to explore for storm deposits and tune geochemical and other proxies for extended study over time scales of several decades or longer.

Monitoring of nature-based solution for stabilizing eroded muddy coastline of the Chao Phraya Delta, Thailand

The Chao Phraya Delta (CPD), Thailand’s largest delta and low-lying muddy coast, has experienced shoreline recession for over six decades due to relative sea-level rise. A nature-based solution, bamboo fences, widely used in low-lying tropical areas, have been intensely applied along the CPD coastline during the last two decades. This study evaluated the effectiveness of bamboo fences in protecting eroded CPD coastlines using remote sensing data (aerial photographs, satellite imagery, and LiDAR observation data). Results from this study indicate that the effectiveness of bamboo fences in trapping sediment decreased over time due to the deterioration of bamboo, which generally deteriorates within four years. Additionally, the installation of multiple layers of bamboo fences did not directly increase the effectiveness of the structure in stabilizing the CPD coastline. It was also found that the mangrove shoreline can be successfully regenerated in the CPD coast where the seabed is higher than 0.5 m amsl. Because of the short life of the bamboo fences, the bamboo fence may not be the best solution for coastal protection and sustainable coastal management in a low-lying area with a high rate of shoreline recession and a low rate of sedimentation.

Holocene ostracods (Crustacea) from a whale-fall excavation site from the Chao Phraya delta, Central Thailand

Late Holocene ostracods were recovered from marine sediments of the Chao Phraya delta at a whale-fall excavation site located fifteen kilometers on land in the Am Pang Subdistrict, Ban Paew District, Samut Sakhon Province, north of the Gulf of Thailand. Thirteen species belonging to seven genera are identified. The deposition environment of the succession is for the first time characterized. The ostracod assemblages suggest that the entire succession associated with the whale-fall deposited in a shallow marine environment such as estuary, bay, inner shelf, subtidal, under less than 20 meters water-depth, in brackish to normal salinity with high mud content and turbidity, on a muddy substrate. This analysis is an important step toward the first in-depth study of ostracods associated with modern and fossil shallow-water whale-falls.

Effectiveness of grey and green engineered solutions for protecting the low-lying muddy coast of the Chao Phraya Delta, Thailand

Coastal protection measures can be categorized into grey and green solutions in terms of their ecosystem impacts. As the use of grey solutions has become a serious issue due to environmental consequences during the last few decades, green/nature-based solutions have become prioritized. This study evaluates the effectiveness of grey and green solutions applied along the eastern Chao Phraya Delta (ECPD) based on historical shoreline change analysis and coastal observations using Light Detection and Ranging technology. The results from shoreline analysis indicate that nearshore breakwaters installed 100–250 m from the shoreline have successfully reclaimed the coastline with a sedimentation rate of 17–23 cm/y. Meanwhile, sand-sausage-submerged breakwaters were ineffective at stabilizing the coastline during 2002–2010 due to land subsidence. With a low subsidence rate, the rubble-mound-submerged breakwaters can reduce the shoreline retreat rate with a vertical deposition rate of about 5 cm/y. In contrast, use of a bamboo fence, a green solution widely used along muddy coasts, traps sediment at a rate of less than 1.3 cm/y and typically lasts only for 2–3 years after installation. Decomposed bamboo causes environmental degradation so local communities disapprove of the approach. Results reveal that grey solutions are more effective for stabilizing the ECPD coastline and result in less coastal environmental impact than the nature-based solution using a bamboo fence.

The Mekong Delta in Vietnam and Cambodia Is Subsiding and in Need of Remediation

Land subsidence and rising sea levels could result in 40% of the Mekong Delta being covered by the South China Sea within the next few decades. The impact of groundwater withdrawal, in the SE Asia mega deltas of Ganges-Brahmaputra Delta, Jakarta Delta, Chao Phraya Delta and Mekong Delta, is a major reason these deltas are sinking. There are lessons to be learned from both failures and successful remediation efforts in other mega deltas as Vietnam policy makers seek to address Mekong Delta subsidence. Without a significant Vietnam government remediation and mitigation efforts, land subsidence in the Mekong Delta will continue. Land subsidence has occurred in the Mekong Delta as a result of the retention of sediments behind the China and Laos dams on the main stem of the Mekong River, reduced flooding peaks, climate change, sea level rise, storm surges and flooding. In addition, subsidence has been exascerbated by compaction, groundwater extraction for shrimp ponds, rice paddies and the household and drinking water needs of approximately 20 million people living on the Mekong Delta in Vietnam and Cambodia. The Mekong Delta shorelines are eroding and significant land areas, including wetlands, are becoming open water. The wetlands and land mass are also subsiding as a result of the reduction in sediment deposition. Large dams on the mainstem of the Mekong River in China and Laos have reduced peak flows and reduced sediment loads in lower Mekong River. Population and industrial growth have increased groundwater extraction and salt water intrusion as the delta subsides leading to consolidation and reduction in the current plumes flowing into the South China Sea. The primary objective of this paper is to assess the impact of groundwater withdrawals for rice paddies, shrimp ponds, aquaculture, industry and drinking water on Mekong Delta land subsidence. The secondary objective is to identify mitigation efforts used in other Southeast Asia deltas and make remediation recommendations for the sinking Mekong Delta. Promising mitigation approaches are injecting river water deep into the underlying alluvial sediments, return of the sediments trapped in China and Laos reservoirs to the Mekong River mainstem, increase in the Mekong River flooding peaks, and construction of sea and floodwalls, dykes, polders and levees. The addition of Mekong River sediments to build up existing floodplains, the reduction of coastal shoreline erosion, the planting of mangroves and protection of urban and agricultural areas from being covered by the South China Sea are strategies that could help remediate land subsidence in the Mekong Delta.

Effects of Dam Construction in the Wang River on Sediment Regimes in the Chao Phraya River Basin

The Wang River is one of the major tributaries of the Chao Phraya River (CPR) system in Thailand as the key riverine sediment source supplying the Chao Phraya Delta that has experienced severe shoreline retreat in the past six decades. Historical and observed river flow and sediment data measured during 1929–2019 were used to assess the variation in total sediment load along the Wang River and evaluate the effects of three major dam constructions on sediment supplied from the Wang River to the CPR. Results indicated that sediment loads increased toward downstream. Variation in long-term total sediment load (TSL) along the river suggested that construction of the Kiew Lom Dam in 1972 did not cause a reduction in sediment yield in the Wang River Basin because it impounded less than 20% of the average annual runoff, while the Mae Chang and Kiew Koh Ma Dams caused downstream sediment reduction. These three dams are located in the upper and middle river basins, and their effects on sediment load in the Wang River are ameliorated by additional sediment supplied from the lower basin. Results confirmed that construction of these three major dams in the Wang River did not greatly impact sediment supply from the Wang River to the CPR system. The dam site and sediment load variation along the river are the primary factors controlling the impact of the dam construction.

Effect of hot wind on insects in longan (Dimocarpus longan Lour.) orchard during off-season production in the Chao Phraya Delta

Effect of hot wind on insects in longan (<i>Dimocarpus longan</i> Lour.) orchard during off-season production in the Chao Phraya Delta

Intensification of rice cultivation in the floodplain of the Chao Phraya delta

Intensification of rice cultivation in the floodplain of the Chao Phraya delta

Did the Construction of the Bhumibol Dam Cause a Dramatic Reduction in Sediment Supply to the Chao Phraya River?

The Bhumibol Dam on Ping River, Thailand, was constructed in 1964 to provide water for irrigation, hydroelectric power generation, flood mitigation, fisheries, and saltwater intrusion control to the Great Chao Phraya River basin. Many studies, carried out near the basin outlet, have suggested that the dam impounds significant sediment, resulting in shoreline retreat of the Chao Phraya Delta. In this study, the impact of damming on the sediment regime is analyzed through the sediment variation along the Ping River. The results show that the Ping River drains a mountainous region, with sediment mainly transported in suspension in the upper and middle reaches. By contrast, sediment is mostly transported as bedload in the lower basin. Variation of long-term total sediment flux data suggests that, while the Bhumibol Dam does effectively trap sediment, there was only a 5% reduction in sediment supply to the Chao Phraya River system because of sediment additions downstream.

An analysis of the factors responsible for the shoreline retreat of the Chao Phraya Delta (Thailand)

Deltas are inherently low-lying structures and thus subject to large threats due to sea level rise, erosion and other coastal processes. The shorelines in many deltas around the world are now retreating and most cases appear to result from a decreasing sediment supply as a consequence of upstream dam construction. We present here results of an investigation of riverine sediment fluxes, coastal retreat, and coastal sediment accumulation in the Chao Phraya River and Delta (Thailand). This deltaic shoreline has one of the highest rates of shoreline retreat in the world. Surprisingly, our results show that in spite of the construction of two large storage dams, one on the Ping River (Bhumibol Dam, 1964) and the other on the Nan River (Sirikit Dam, 1972) that merge to form the Chao Phraya, sediment accumulation in the delta was actually higher over the last several decades than prior to dam construction. The recent higher rates of sediment accumulation, based on 210Pb dating, appear to be the result of increased sediment supply in the lower reaches of the river relating to expansion of aquaculture and other activities in the delta beginning in the 1970s. We also show that mangrove removal, in order to further develop shrimp farming, charcoal production, and other pursuits, was not responsible for most of the shoreline erosion. Rather, subsidence, mainly induced by groundwater withdrawal, together with worldwide sea level rise appears to be the main factor affecting the very rapid shoreline retreat of the Chao Phraya Delta.

Managing the Chao Phraya River and Delta in Bangkok, Thailand: Flood Control, Navigation and Land Subsidence Mitigation

Land subsidence as a result of the groundwater withdrawals in the Chao Phraya Delta in Thailand will be studied along with any successful remediation efforts. Most of the deltas of South East Asia are sinking for a variety of reasons. Thailand has national concerns related to land subsidence as a result of sea level rise, climate change, flooding, storm surges, skyscrapers, compaction, and groundwater extraction for rice paddies, shrimp ponds and the drinking water and household needs of approximately 15 million people living on the Chao Phraya Delta. The Chao Phraya River shoreline line is eroding and significant land areas and wetlands are being lost and becoming open water. Urban areas are periodically flooded and require earthen levees or floodwalls. The objective is to assess and mitigate land subsidence as a result of groundwater withdrawals for rice paddies, aquaculture, shrimp ponds, industry, drinking water and household needs of 15 million people living on Chao Phraya Delta in Bangkok. The impact of groundwater extraction and reduced sedimentation on land subsidence in the Chao Phraya Delta will be assessed and mitigation methods recommended. Lessons learned and successful remediation efforts in one Southeast Asia delta may or may not be applicable to other South East Asia deltas. There need to be mitigation methods identified to add sediment to existing Chao Phraya Delta wetlands. River water also needs to be injected deep into the underlying alluvial sediments in the delta. Navigation in the canal systems could be adversely affected by proposed massive Chao Phraya River water injections into the Chao Phraya Delta alluvial sediments underlying Bangkok.

Is Bangkok at risk of marine flooding? Evidence relating to the historical floods of AD 1785 and 1983

Thailand’s low-lying capital city Bangkok is a dense metropolis, one of Asia’s rapidly growing ‘megacities’, and home to over 10 million residents. Bangkok’s location on the sinking Chao Phraya Delta means it has a high susceptibility to river flooding. However, the possible contribution of marine incursion to river flooding is not as widely recognised and needs further consideration. We therefore re-examine the historically documented floods in AD 1785 and 1983. Available evidence suggests that the superposition of different flood behaviours was important during both events. Attention is drawn to the evidence for, and contributory roles played by, astronomical spring tides, meteorological tides, storm waves and possibly storm surge. These marine effects can exacerbate river floods caused by seasonal peak flows in the tidal lower Chao Phraya River during the early north-east monsoon. For future management of flood risk, it is therefore necessary to recognise that Bangkok has a compound flood-risk profile that includes both hydrometeorological and marine influences. The significance of marine influences on Bangkok’s flood risk is likely to increase in future with continuing eustatic sea-level rise and subsidence of the Chao Phraya Delta.

Morphology of the Agriculture-based Deltaic Settlement in the Western Basin of the Chaophraya Delta

The morphology of the horticulture based deltaic settlement in the Western Basin of Chaophraya Delta is clarified through an examination of the connection between the accompanying elements; geographical conditions and recorded and social foundation. This likewise mirrored the creation from land advancement, and the settlement development process. We isolated the example of settlement arrangement into 3 sorts; (1) Multi-driven organization settlement, (2) Strip-hub settlement, and (3) Single-driven settlement. These were then classified through thought of an examination interaction on the geological segment of the north-south and west-east pivot of the Delta. Just as adjusting to the deltaic geological highlights, it very well may be viewed as that the examples and change interaction of these settlements were situated in resembled with; (1) inception of the Phrai framework, and (2) a declination of the Phrai framework. The Chinese merchants, who coordinated the waterfront market organization, could likewise be viewed as the key people who propelled this cycle. It very well may be viewed as that the multi-driven organization settlement was created under the influence of the Phrai framework, while the fish-bone sort strip-pivot settlement was created later a declination of the Phrai framework.

Difficult travels: Delta plans don’t land in the Chao Phraya delta

Bangladesh, Myanmar, Vietnam and Thailand have large river deltas. The first three deltas have international commitments for so-called delta plans: large-scale national efforts to reshape deltas in light of future economic growth and climate change. Thailand’s Chao Phraya delta has no such commitments. Why is this the case? This article proposes that Thailand’s absence of a colonial past has retained a differently ordered institutional capacity and that Delta plans embed assumptions that fit poorly with a Thai worldview. The article relies on literature and adds original research collected on three separate field visits to Thailand.

Major typhoon phases in the upper Gulf of Thailand over the last 1.5 millennia, determined from coastal deposits on rock islands

Rapid growth of Asian megacities, exemplified by the megacity of Bangkok, Thailand, with a population of over 10 million inhabitants, means that an increasing number of people are living in low-lying coastal areas exposed to hazards such as typhoons. While Bangkok has always been considered not to be at risk from typhoon strikes, recent discoveries of elevated carbonate boulder deposits have started to question this assumption. This work reports on findings from the islands of Ko Khang Khao and Ko Phai, farther north and west than earlier studies, and adds to the existing body of evidence for prehistorical typhoon-driven high energy marine inundation (HEMI) events penetrating northwards into the Bay of Bangkok. Elevated carbonate boulder deposits up to 6 m amsl indicate that these were emplaced by waves generating onshore minimum flow velocities between 3.0 and 5.5 m/s, consistent with typhoon-impacted coastlines elsewhere in the tropical Asia-Pacific region. When viewed in conjunction with other data from the Bay of Bangkok their chronologies indicate age clusters around four major phases of activity in AD 600–700, AD 900–1000, AD 1150–1250 and AD 1400–1650. At 250 years duration, the last phase of activity was the longest, but it has also been followed by the longest period of quiescence that has coincided with rapid urban growth in and around the city of Bangkok. The re-occurrence of typhoon-driven HEMI events on the scale of the prehistorical events reported here would threaten all the low-lying coasts in the Bay of Bangkok, including the Chao Phraya delta, and as such these results indicate an urgent need to re-evaluate coastal hazards for the region.

From Gravitational Machine to Universal Habitat: The Drainage Basin and Amphibious Futures in the Chao Phraya Delta, Thailand

This paper elucidates the development of the drainage basin model, one particular frame for capturing the relative motion between water and land, by highlighting the parallel developments between scientific notion and water management infrastructures. Facilitating a continuous movement back and forth between science and infrastructure, the drainage basin allows for the revelation of unexpected forms of relatedness and has played an important role in the emergence of a form of relational morality. To make this argument, this paper focuses on the Chao Phraya Delta in Thailand. While located in the periphery of the centers of modern science, the delta holds significance as a place where colonial hydrological technoscience and indigenous development intersected. The encounter between the two has resulted in a new vision of the city as a waterscape, a sort of drainage basin that connects natural, social and economic processes through numerous, complex water flows.

Multispecies Infrastructure: Infrastructural Inversion and Involutionary Entanglements in the Chao Phraya Delta, Thailand

ABSTRACTThis paper aims to elucidate the central role floating rice has played in the formation of water management infrastructure in the Chao Phraya delta in Thailand. Operating in the background of everyday activities, infrastructures often remain overlooked by the actors that rely on them. However at certain moments, such as breakdowns, infrastructures make visible usually hidden connections between humans and non-humans. In recent years, the infrastructural role of floating rice has become a matter of concern for many actors in and around the Chao Phraya delta. This paper examines the particular multispecies relations between water management infrastructure, farmers and rice in the delta. In particular, the paper traces moments of infrastructural inversion that shed light on rice's involutions as part of a multispecies infrastructure. Attention to these involutions, the paper argues, facilitates a reconsideration of infrastructure's relationship with nature.

Prehistorical frequency of high‐energy marine inundation events driven by typhoons in the Bay of Bangkok (Thailand), interpreted from coastal carbonate boulders

AbstractRapidly rising populations of low‐lying megacities in Asia mean that understanding the potential risk of coastal flooding by storm surge is of paramount concern. The city of Bangkok and the wider Chao Phraya River delta at the head of the Gulf of Thailand is a region topographically vulnerable to coastal flooding, but without the record of a high‐energy marine inundation (HEMI) event in historical time owing to the atypical path that a typhoon must take to be able to produce such an event.This work builds upon previous findings that identified coastal depositional evidence for HEMI events in the form of coastal carbonate boulders (CCBs) located on Ko Larn Island in the eastern Bay of Bangkok. The HEMI events were most likely driven by typhoons and the CCBs are therefore interpreted as typhoon deposits. Through uranium/thorium dating, it is revealed that from ad 1400 to ad 1600 the Bay of Bangkok possibly experienced a phase of relatively heightened storm impact. During this period, the frequency of typhoon‐driven HEMI events was approximately four events in 200 years. Waves generated onshore minimum flow velocities (MFVs) in excess of 5 m/s. Such exceptional MFVs are unlikely to be produced during the annual northeast monsoon, but are consistent with typhoon‐impacted coastlines elsewhere in the tropical Asia–Pacific region where similar CCB evidence exists. Since ad 1600, the Bay of Bangkok has enjoyed a relatively quiescent phase, recording less frequent HEMI events and of lower magnitude. However, the re‐occurrence of a typhoon‐driven HEMI event on the scale of the prehistorical events that emplaced carbonate boulders at elevation on Ko Larn Island would threaten low‐lying coasts in the Bay of Bangkok, including the Chao Phraya delta, with potentially damaging inundation. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Infrastructuring Amphibious Space: The Interplay of Aquatic and Terrestrial Infrastructures in the Chao Phraya Delta in Thailand

The historic flooding that occurred in 2011 in central Thailand revealed fierce struggles over flood protection, which were made particularly complex because of the unruly nature of water itself. The interplay between two forms of infrastructure, each of which shape the flows of water coursing through the Chao Phraya Delta, is key to understanding this complexity. As an ambiguous place in between the sea and land, a delta environment can be seen alternatively as an extension of the sea or as reclaimable land. Constructing infrastructures based on either of these views remakes the landscape accordingly—thus making the landscape more terrestrial or more aquatic. In the Chao Phraya Delta, the terrestrial infrastructure, which consists of road networks and land-based urban living, has been overlaid on a pre-existing aquatic infrastructure characterized by canal transport and flood adaptive architecture. Mainly due to state interest in facilitating water transport, the aquatic infrastructure organized the landscape of the delta until the mid-twentieth century. However, since then the introduction of modern irrigation has progressively rendered the delta landscape more terrestrial. Dry land created by the irrigation system made modern forms of agriculture, commerce and industry possible. While this terrestrial trend seemed to take over the entire delta, the terrestrial infrastructure did not eliminate the aquatic one. Instead it created a dynamic interplay between different forms of infrastructure. The 2011 flood foregrounded the centrality of this interplay in flood protection and sheds new light on the role of the aquatic infrastructure.