- Email: [email protected]
Tephras from source to sink on an active plate margin: providing a chronology for events in the Waipaoa Catchment, East Coast North Island, New Zealand
Abstracts / Quaternary International 279-280 (2012) 346–461
Abnormal and rapid rise of the Caspian Sea level is a pervasive and complex hazard and threats all coastal vulnerable elements at regional scale. It has been recognized to be an intrinsic part of the coupled process and self-induced hazard, leading to soil salinization and further land degradation. As a result of rapid sea level rise by 2.5 m ( 26.5m) during 1978-1995 the extensive areas of the Caspian coasts were flooded and serious ecological and economic damages have been caused to coastal environments and human societies. In this long and continuous cycle of transgression the very low rate natural desalinization process of ancient sea beds has changed to rapid and complex desertification and caused to intense land degradation through flooding ,ponding, salt water intrusion, water table rising ,salinization and affected all coastal zone land use plans by different radius and intensity. In spite of critical uncertainties and eustatic paradox, one of the long term prediction is sea level catastrophic rise up to 22m in 2050, that will threat by high risk all coastal zone environmental elements and projects. Direct and indirect, partial and total risk perspective of gradual or sudden transgression of sea water up to 22 m in the low coastal plain of Gorgan Bay will be diverse and tremendous and cause to a new geo-eco-disaster of dark nature. Relative to sea level of 29 m in 1977, during the recent period of rapid rising (1978-1995) the sea water penetrated more than 5 km in coastal plain and submerged all lands and elements, and triggered the land degradation intensity by 1 to 2 classes. At 22 m as a high risk scenario in coming decades, vast area with different human and geo-ecological elements will submerge and sea salt water frontal desertified area (class IV) extent up to 15 km especially along the Gorgan-Rud and Qara-Su rivers and surrounding low lands.
THE BEHAVIOR OF ARSENIC WITH SEASONAL CHANGE IN WATER LEVEL AROUND LAKE TONLE SAP, CAMBODIA Hideo Oyagi. Nihon University, Japan
365
Vembanad Lagoon is the largest back water system in the southwestern coast of India. The area hosting Vembanad Lagoon comprises a spectrum of landform features that include barrier islands, beach ridges and swales, tidal flats and floodplains. The coast is known for its attractive occurrence of ilmenite rich beach placers in the south, limeshells in the lagoon and over bank areas, and high purity silica sands in the ridges and swales separating the lagoon from the Arabian Sea. A total of eight borehole cores with length ranging from 15m to 42m has been retrieved from the coastal lands of the Vembanad Lagoon and studied for sedimentological, palynological, geochronological and stable isotopic (d13Corg and d15N) characteristics with an aim to unfold the Late Quaternary evolution of the lagoonbarrier system. The study reveals that the Vembanad Lagoon has evolved enclosing a part of the Arabian Sea by deposition of sediments from the inner shelf areas under the rising spells of sea levels and heavy rainfall climatic events of the Early Holocene period. The depositional regimes and evolutionary processes showed marked differences in the northern and southern reaches of the Vembanad Lagoon. The wider southern half of the Lagoon has been separated during the progradation and development of a barrier spit across an embayment in the Arabian Sea. The occurrence of marine elements in the palynological preparations, d13Corg values of around -24& and sillimanite rich heavy mineral residue are indicative of barrier spit development from a sediment source far south of the Lagoon. The northern half, on the other hand, has evolved from a coastal peat deposit (C14 date 9250170 BP and d13 Corg values of 26&) during the transgressive- regressive events to which the coast has been subjected during the Holocene epoch. TEPHRAS FROM SOURCE TO SINK ON AN ACTIVE PLATE MARGIN: PROVIDING A CHRONOLOGY FOR EVENTS IN THE WAIPAOA CATCHMENT, EAST COAST NORTH ISLAND, NEW ZEALAND Alan Palmer. Massey University, New Zealand E-mail address: [email protected]
E-mail address: [email protected]
Lake Tonle Sap situating in the lower reaches of the Mekong River basin is the largest lake in its surface area in Southeast Asia. The lake has a close relation to the regional society, culture and life of people in Cambodia. Consequently, it is important to make clear the temporal changes of the hydrological characteristics in order to establish the water management project for the ecosystem in the Mekong River basin. From the viewpoint of both water resources and hydrological environment, fundamental data on physicochemical characteristics of the lake should be collected and analyzed in order to sustain the better scheme of water management. The purpose of the present study is to evaluate the water quality of the lake as affected by the fluctuation of water level as well as by the human activity. Especially, the present study pays attention to the concentration of distribution of the arsenic around the Lake Tonle Sap in Cambodia. Arsenic is a metalloid element, which forms a number of poisonous compounds. It is widely distributed throughout the earth’s crust, and is found in groundwater supplies in South Asia of countries. The spatial distribution of arsenic of the waters in the Siem Reap River is less than 0.01mg/L. However, it of central Lake Tonle Sap reaches 0.0089 mg/L. The acceptable level as defined by WHO for maximum concentrations of arsenic in safe drinking water is 0.01 mg/L. According to UNICEF reports, in spite of increased risk areas are widely distributed along the lower reaches of the Mekong River in Cambodia, the area of Siem Reap is classified into the low or very low risk areas. These results are considered that the water quality of lake represents affect by the river water from Mekong River. Moreover, on the water exchange mechanisms of the lake, the water in the central lake should be remains of the water from the Mekong River.
LATE QUATERNARY EVOLUTION OF VEMBANAD LAGOON IN THE SOUTHWESTERN COAST OF INDIA: AN APPRAISAL OF SEDIMENTARY RECORD OF SEA LEVEL AND CLIMATE CHANGE D. Padmalal. Centre for Earth Science Studies, India E-mail address: [email protected]
The Waipaoa River Catchment on the East Coast of the North Island of New Zealand has become one of the best documented source to sink studies. The chronology for this study has been enhanced by the presence of major silicic tephras, on average every 2000 years since the Last Glacial Maximum. These tephras are sourced from the Taupo Volcanic Zone, 100200 km west and upwind of the Catchment. The Waipaoa River drains a small 2150 km2 catchment that delivers 15 million tonnes of sediment annually to the Pacific Ocean, a rate of erosion and subsequent deposition that is very high by international standards. The East Coast of the North Island is a fore-arc on the outer edge of the Australian Plate, above the subducting Pacific Plate. The subduction has produced broad regional uplift of at least 1 mm yr 1, matched by rapid fluvial incision and erosion. The Catchment geology is complex, ranging from structurally weakened Cretaceous and Early Tertiary allochthonous sediments in the headwaters to Miocene and Pliocene marine sediments in the middle reaches. Tephras have accumulated on stable parts of the landscape, for example, undissected uplands, interfluves, river aggradation terraces, fans and degradation terraces. The same tephras may be trapped and preserved within sediment accumulation sites such as 3rd order subcatchments awaiting excavation, colluvial slopes, river terrace deposits, oxbows, floodplains and sediment sink areas on the continental shelf, slope and abyssal plain. Thus the tephras are chronological markers that allow sediment budgets to be prepared in sediment source areas, transport zones, storage areas and eventual sinks. Paleosols between the tephras can be interpreted for paleoclimatic and paleoenvironmental information, and are records of what was happening on that component of landscape between tephra falls. A LATE-HOLOCENE RECORD OF MARINE WASHOVER EVENTS FROM A COASTAL LAGOON IN JAMAICA, WEST INDIES Suzanne Palmer. University of Chester, United Kingdom E-mail address: [email protected]
Coastal lagoons provide excellent repositories of marine washover events within the sediment record. There remains, however, an
Abnormal and rapid rise of the Caspian Sea level is a pervasive and complex hazard and threats all coastal vulnerable elements at regional scale. It has been recognized to be an intrinsic part of the coupled process and self-induced hazard, leading to soil salinization and further land degradation. As a result of rapid sea level rise by 2.5 m ( 26.5m) during 1978-1995 the extensive areas of the Caspian coasts were flooded and serious ecological and economic damages have been caused to coastal environments and human societies. In this long and continuous cycle of transgression the very low rate natural desalinization process of ancient sea beds has changed to rapid and complex desertification and caused to intense land degradation through flooding ,ponding, salt water intrusion, water table rising ,salinization and affected all coastal zone land use plans by different radius and intensity. In spite of critical uncertainties and eustatic paradox, one of the long term prediction is sea level catastrophic rise up to 22m in 2050, that will threat by high risk all coastal zone environmental elements and projects. Direct and indirect, partial and total risk perspective of gradual or sudden transgression of sea water up to 22 m in the low coastal plain of Gorgan Bay will be diverse and tremendous and cause to a new geo-eco-disaster of dark nature. Relative to sea level of 29 m in 1977, during the recent period of rapid rising (1978-1995) the sea water penetrated more than 5 km in coastal plain and submerged all lands and elements, and triggered the land degradation intensity by 1 to 2 classes. At 22 m as a high risk scenario in coming decades, vast area with different human and geo-ecological elements will submerge and sea salt water frontal desertified area (class IV) extent up to 15 km especially along the Gorgan-Rud and Qara-Su rivers and surrounding low lands.
THE BEHAVIOR OF ARSENIC WITH SEASONAL CHANGE IN WATER LEVEL AROUND LAKE TONLE SAP, CAMBODIA Hideo Oyagi. Nihon University, Japan
365
Vembanad Lagoon is the largest back water system in the southwestern coast of India. The area hosting Vembanad Lagoon comprises a spectrum of landform features that include barrier islands, beach ridges and swales, tidal flats and floodplains. The coast is known for its attractive occurrence of ilmenite rich beach placers in the south, limeshells in the lagoon and over bank areas, and high purity silica sands in the ridges and swales separating the lagoon from the Arabian Sea. A total of eight borehole cores with length ranging from 15m to 42m has been retrieved from the coastal lands of the Vembanad Lagoon and studied for sedimentological, palynological, geochronological and stable isotopic (d13Corg and d15N) characteristics with an aim to unfold the Late Quaternary evolution of the lagoonbarrier system. The study reveals that the Vembanad Lagoon has evolved enclosing a part of the Arabian Sea by deposition of sediments from the inner shelf areas under the rising spells of sea levels and heavy rainfall climatic events of the Early Holocene period. The depositional regimes and evolutionary processes showed marked differences in the northern and southern reaches of the Vembanad Lagoon. The wider southern half of the Lagoon has been separated during the progradation and development of a barrier spit across an embayment in the Arabian Sea. The occurrence of marine elements in the palynological preparations, d13Corg values of around -24& and sillimanite rich heavy mineral residue are indicative of barrier spit development from a sediment source far south of the Lagoon. The northern half, on the other hand, has evolved from a coastal peat deposit (C14 date 9250170 BP and d13 Corg values of 26&) during the transgressive- regressive events to which the coast has been subjected during the Holocene epoch. TEPHRAS FROM SOURCE TO SINK ON AN ACTIVE PLATE MARGIN: PROVIDING A CHRONOLOGY FOR EVENTS IN THE WAIPAOA CATCHMENT, EAST COAST NORTH ISLAND, NEW ZEALAND Alan Palmer. Massey University, New Zealand E-mail address: [email protected]
E-mail address: [email protected]
Lake Tonle Sap situating in the lower reaches of the Mekong River basin is the largest lake in its surface area in Southeast Asia. The lake has a close relation to the regional society, culture and life of people in Cambodia. Consequently, it is important to make clear the temporal changes of the hydrological characteristics in order to establish the water management project for the ecosystem in the Mekong River basin. From the viewpoint of both water resources and hydrological environment, fundamental data on physicochemical characteristics of the lake should be collected and analyzed in order to sustain the better scheme of water management. The purpose of the present study is to evaluate the water quality of the lake as affected by the fluctuation of water level as well as by the human activity. Especially, the present study pays attention to the concentration of distribution of the arsenic around the Lake Tonle Sap in Cambodia. Arsenic is a metalloid element, which forms a number of poisonous compounds. It is widely distributed throughout the earth’s crust, and is found in groundwater supplies in South Asia of countries. The spatial distribution of arsenic of the waters in the Siem Reap River is less than 0.01mg/L. However, it of central Lake Tonle Sap reaches 0.0089 mg/L. The acceptable level as defined by WHO for maximum concentrations of arsenic in safe drinking water is 0.01 mg/L. According to UNICEF reports, in spite of increased risk areas are widely distributed along the lower reaches of the Mekong River in Cambodia, the area of Siem Reap is classified into the low or very low risk areas. These results are considered that the water quality of lake represents affect by the river water from Mekong River. Moreover, on the water exchange mechanisms of the lake, the water in the central lake should be remains of the water from the Mekong River.
LATE QUATERNARY EVOLUTION OF VEMBANAD LAGOON IN THE SOUTHWESTERN COAST OF INDIA: AN APPRAISAL OF SEDIMENTARY RECORD OF SEA LEVEL AND CLIMATE CHANGE D. Padmalal. Centre for Earth Science Studies, India E-mail address: [email protected]
The Waipaoa River Catchment on the East Coast of the North Island of New Zealand has become one of the best documented source to sink studies. The chronology for this study has been enhanced by the presence of major silicic tephras, on average every 2000 years since the Last Glacial Maximum. These tephras are sourced from the Taupo Volcanic Zone, 100200 km west and upwind of the Catchment. The Waipaoa River drains a small 2150 km2 catchment that delivers 15 million tonnes of sediment annually to the Pacific Ocean, a rate of erosion and subsequent deposition that is very high by international standards. The East Coast of the North Island is a fore-arc on the outer edge of the Australian Plate, above the subducting Pacific Plate. The subduction has produced broad regional uplift of at least 1 mm yr 1, matched by rapid fluvial incision and erosion. The Catchment geology is complex, ranging from structurally weakened Cretaceous and Early Tertiary allochthonous sediments in the headwaters to Miocene and Pliocene marine sediments in the middle reaches. Tephras have accumulated on stable parts of the landscape, for example, undissected uplands, interfluves, river aggradation terraces, fans and degradation terraces. The same tephras may be trapped and preserved within sediment accumulation sites such as 3rd order subcatchments awaiting excavation, colluvial slopes, river terrace deposits, oxbows, floodplains and sediment sink areas on the continental shelf, slope and abyssal plain. Thus the tephras are chronological markers that allow sediment budgets to be prepared in sediment source areas, transport zones, storage areas and eventual sinks. Paleosols between the tephras can be interpreted for paleoclimatic and paleoenvironmental information, and are records of what was happening on that component of landscape between tephra falls. A LATE-HOLOCENE RECORD OF MARINE WASHOVER EVENTS FROM A COASTAL LAGOON IN JAMAICA, WEST INDIES Suzanne Palmer. University of Chester, United Kingdom E-mail address: [email protected]
Coastal lagoons provide excellent repositories of marine washover events within the sediment record. There remains, however, an