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Relationship between Groundwater Quality and Human Activity - A Case Study in the Arakawa Alluvial Fan, Japan
Abstracts / Quaternary International 279-280 (2012) 346–461
PAST AND PRESENT PERMAFROST DISTRIBUTION IN THE NORTHERN AND SOUTHERN HEMISPHERE: COMPARISON OF THE GCM-BASED MAPPING WITH THE OBSERVATIONS Kazuyuki Saito. JAMSTEC, Japan E-mail address: [email protected]
Freeze/thaw dynamics of soil is a decisive factor in the cold-regions ecoclimate systems. Changes in the subsurface thermal regimes and the distribution of frozen ground in time and space are important in understanding the attribution and consequence of Quaternary climate change. A combined modeling of the large-scale climate and land processes with physically-based freeze/thaw dynamics have not extensively employed yet. As a preliminary step, we constructed a FG mapping from the near-surface atmospheric thermal conditions (freeze and thaw indices), that could reasonably reconstruct the large-scale FG distribution in the NH despite simplifications of the determining factors in the reality (e.g., vegetation, soil, snow, and topography). It was applied to the late Quaternary conditions of the both hemispheres for 0ka (pre-industrial), 6ka (mid-Holocene), and 21ka (the last glacial maximum; LGM), modeled by global climate models (GCMs) participating the Paleoclimate Model Intercomparison Project 2 (PMIP2). The NH results were compared against reconstruction maps by Frenzel et al. (1992) and Velichko (1984), while the SH results were compared with the evidence obtained by observations in Patagonia and the Andean region (Trombotto 2002), and a map of winter freeze in Patagonia. The Holocene results (0ka and 6ka) were largely similar to each other with common cool biases. The LGM showed substantial increase of the permafrost, but also insufficient cooling during the cold season in some regions (e.g., north of the Alps). The majority of the models produced no freezing in the SH or, at most, seasonal frost in the Andes for 0ka, partly due to coarse topographic resolution (similar to the Himalayas for NH). Use of highresolution topography data improved the regional details of the FG distributions such as Andean permafrost for 0ka, but still failed to reconstruct lowland permafrost in the high- and mid-latitude regions.
HOLOCENE DELTA EVOLUTION AND RECENT CHANGES IN ASIA Yoshiki Saito. Geological Survey of Japan, AIST, Japan E-mail address: [email protected]
Asian coasts are characterized by large-river deltas, called megadeltas, which are identified as one of most vulnerable areas in the world with respect to global climate change currently. Three keywords characterize the present delta crisis: shrinking deltas, sinking deltas, and ecosystem collapse. Shrinking and sinking deltas are caused mainly by a decrease in the amount of sediment supplied by rivers to deltas and deltaic coasts, as well as by a relative sea-level rise, either eustatic or caused by land subsidence. Asian megadeltas were initiated at ca. 8.0 ka after a rapid sea-level rise at 8.4-8.5 ka. Outbuilding (progradation) of mega-deltas has occurred continuously seaward, related to huge sediment supply and relatively stable sea level since the middle Holocene. Particularly continental large rivers in Southeast and East Asia together supplied w2.5 109 tons/y of suspended sediment 30-40 years ago, which is more than 10 % of global sediment discharge, and formed more than 40 km2 of new land annually as delta plains, resulting from increased sediment discharge by human activities (e.g., deforestation) on a millennial scale. However they are delivering less than 1 109 tons/y currently because of another human activities (e.g., the reduction of sediment supply and relative sea-level rise caused by human activities), which is close to a pristine level of sediment discharge on these rivers in the middle Holocene. New land formation has come to a standstill, and some deltas are even shrinking, currently. The megadeltas of Asia are thus at risk of destruction at present after delta construction since the middle Holocene. RELATIONSHIP BETWEEN GROUNDWATER QUALITY AND HUMAN ACTIVITY - A CASE STUDY IN THE ARAKAWA ALLUVIAL FAN, JAPAN Isao Saito. Nihon University, Japan E-mail address: [email protected]
423
The Arakawa alluvial fan located in the Saitama Prefecture northern part of Japan is alluvial fan that extends between Arakawa and Tonegawa. There are many spring water and wells in the Arakawa alluvial fan, and groundwater is used to the rice field and arable area. Namely, groundwater is an important water resource in the human activity. However, people are using a lot of fertilizers to grow farm products. As a result, a high nitric acid is detected in groundwater, and the nitrate pollution of groundwater is environmental problems. The purpose of the present study is to evaluate the influence of the groundwater quality by the human activity. Especially, the present study pays attention to the concentration of nitric acid of formation. The nitric acid is provided in the environmental water-quality standard in Japan, and an important element for considering polluting. Groundwater in the Arakawa alluvial fan is characterized by relatively high concentration of nitric acid. The concentration of nitric acid exceeds environmental water-quality standard according to the area. In the center of the Arakawa alluvial fan, the arable area exists widely, and the ammonium sulfate is used for fertilizer in this area. A constant increasing tendency according to flowing down was observed to the relation between the concentration of nitric acid and sulfuric acid in groundwater. That is, the groundwater pollution is thought that the fertilizer is a cause from the increasing tendency of nitric acid and sulfuric acid. Therefore, the human activity such as fertilizer in the arable area gives serious damage to the groundwater quality. It is concluded that people should have consideration for water, and keep the limited water resource. LIMITS TO ALPINE TOPOGRAPHY Bernhard Salcher. Department of Geology, ETH Zurich, Switzerland E-mail address: [email protected]
Modern topography together with techniques of erosion rate determination can be obtained to unravel associated agents of surface processes. Cosmogenic nuclide surveys on mean catchment erosion rates reveal mean basin slope as a characteristic metric in fluvially dominated landscapes. Erosion rates are shown to increase linearly until a certain point, where slope becomes highly independent of erosion rates. In such landscapes the rate of denudation will be determined by the frequency and magnitude of landsliding controlled by the rate of channel incision. In glacial sculptured landscapes such as the European Alps key basin metrics (relief, slope, channel steepness index) show no significant correlation with erosion rates except mean altitude. Terrain is set into a oversteepend, near threshold stage by processes of glacial erosion. We show that fluvial incision is largest where glacial occupation time was lowest during a glacial cycle and argue that both (mean altitude and fluvial incision) reflect the intensity of glacial occupation on the landscape. While the high Alps have a multiple glaciation history, the lower parts are only affected by glacial maxima. Glacial erosion is lower and basins had a longer time to fluvially readapt. In the oversteepend Alps fluvial incision is counteracted by landsliding and mainly depended on rock strength: We postulate that the varying hillslope angles after glacial retreat are the result of varying rock strength. We further show that measuring the incision depth as well as the drainage density can be used to quantify erosion rates and to make statements on the dependence of glacial occupation and rock strength. PALEOCLIMATIC RECORDS OF QUATERNARY TUFA IN THE SERRA DO ANDRÉ LOPES KARST, SOUTHEASTERN BRAZIL William Sallun Filho. Geological Institute, Brazil E-mail address: [email protected]
The Serra do André Lopes is a karst area situated in a dolomite plateau with a superhumid subtropical climate in the Ribeira de Iguape River valley, in the south of the State of São Paulo. It has tufa deposits in the form of waterfalls and dams. Gastropod shells and tufas were dated by 14C AMS and calibrated with SHCal04 (McCormac et al., 2004). Studies were made of two deposits in the form of paleo-waterfalls found on hillsides. At the location of Sapatú, stratified friable tufas, with irregular to plane-parallel layering, comprise various temporally repeated sequences with an apparent thickness of more than 12 meters. They are composed of
PAST AND PRESENT PERMAFROST DISTRIBUTION IN THE NORTHERN AND SOUTHERN HEMISPHERE: COMPARISON OF THE GCM-BASED MAPPING WITH THE OBSERVATIONS Kazuyuki Saito. JAMSTEC, Japan E-mail address: [email protected]
Freeze/thaw dynamics of soil is a decisive factor in the cold-regions ecoclimate systems. Changes in the subsurface thermal regimes and the distribution of frozen ground in time and space are important in understanding the attribution and consequence of Quaternary climate change. A combined modeling of the large-scale climate and land processes with physically-based freeze/thaw dynamics have not extensively employed yet. As a preliminary step, we constructed a FG mapping from the near-surface atmospheric thermal conditions (freeze and thaw indices), that could reasonably reconstruct the large-scale FG distribution in the NH despite simplifications of the determining factors in the reality (e.g., vegetation, soil, snow, and topography). It was applied to the late Quaternary conditions of the both hemispheres for 0ka (pre-industrial), 6ka (mid-Holocene), and 21ka (the last glacial maximum; LGM), modeled by global climate models (GCMs) participating the Paleoclimate Model Intercomparison Project 2 (PMIP2). The NH results were compared against reconstruction maps by Frenzel et al. (1992) and Velichko (1984), while the SH results were compared with the evidence obtained by observations in Patagonia and the Andean region (Trombotto 2002), and a map of winter freeze in Patagonia. The Holocene results (0ka and 6ka) were largely similar to each other with common cool biases. The LGM showed substantial increase of the permafrost, but also insufficient cooling during the cold season in some regions (e.g., north of the Alps). The majority of the models produced no freezing in the SH or, at most, seasonal frost in the Andes for 0ka, partly due to coarse topographic resolution (similar to the Himalayas for NH). Use of highresolution topography data improved the regional details of the FG distributions such as Andean permafrost for 0ka, but still failed to reconstruct lowland permafrost in the high- and mid-latitude regions.
HOLOCENE DELTA EVOLUTION AND RECENT CHANGES IN ASIA Yoshiki Saito. Geological Survey of Japan, AIST, Japan E-mail address: [email protected]
Asian coasts are characterized by large-river deltas, called megadeltas, which are identified as one of most vulnerable areas in the world with respect to global climate change currently. Three keywords characterize the present delta crisis: shrinking deltas, sinking deltas, and ecosystem collapse. Shrinking and sinking deltas are caused mainly by a decrease in the amount of sediment supplied by rivers to deltas and deltaic coasts, as well as by a relative sea-level rise, either eustatic or caused by land subsidence. Asian megadeltas were initiated at ca. 8.0 ka after a rapid sea-level rise at 8.4-8.5 ka. Outbuilding (progradation) of mega-deltas has occurred continuously seaward, related to huge sediment supply and relatively stable sea level since the middle Holocene. Particularly continental large rivers in Southeast and East Asia together supplied w2.5 109 tons/y of suspended sediment 30-40 years ago, which is more than 10 % of global sediment discharge, and formed more than 40 km2 of new land annually as delta plains, resulting from increased sediment discharge by human activities (e.g., deforestation) on a millennial scale. However they are delivering less than 1 109 tons/y currently because of another human activities (e.g., the reduction of sediment supply and relative sea-level rise caused by human activities), which is close to a pristine level of sediment discharge on these rivers in the middle Holocene. New land formation has come to a standstill, and some deltas are even shrinking, currently. The megadeltas of Asia are thus at risk of destruction at present after delta construction since the middle Holocene. RELATIONSHIP BETWEEN GROUNDWATER QUALITY AND HUMAN ACTIVITY - A CASE STUDY IN THE ARAKAWA ALLUVIAL FAN, JAPAN Isao Saito. Nihon University, Japan E-mail address: [email protected]
423
The Arakawa alluvial fan located in the Saitama Prefecture northern part of Japan is alluvial fan that extends between Arakawa and Tonegawa. There are many spring water and wells in the Arakawa alluvial fan, and groundwater is used to the rice field and arable area. Namely, groundwater is an important water resource in the human activity. However, people are using a lot of fertilizers to grow farm products. As a result, a high nitric acid is detected in groundwater, and the nitrate pollution of groundwater is environmental problems. The purpose of the present study is to evaluate the influence of the groundwater quality by the human activity. Especially, the present study pays attention to the concentration of nitric acid of formation. The nitric acid is provided in the environmental water-quality standard in Japan, and an important element for considering polluting. Groundwater in the Arakawa alluvial fan is characterized by relatively high concentration of nitric acid. The concentration of nitric acid exceeds environmental water-quality standard according to the area. In the center of the Arakawa alluvial fan, the arable area exists widely, and the ammonium sulfate is used for fertilizer in this area. A constant increasing tendency according to flowing down was observed to the relation between the concentration of nitric acid and sulfuric acid in groundwater. That is, the groundwater pollution is thought that the fertilizer is a cause from the increasing tendency of nitric acid and sulfuric acid. Therefore, the human activity such as fertilizer in the arable area gives serious damage to the groundwater quality. It is concluded that people should have consideration for water, and keep the limited water resource. LIMITS TO ALPINE TOPOGRAPHY Bernhard Salcher. Department of Geology, ETH Zurich, Switzerland E-mail address: [email protected]
Modern topography together with techniques of erosion rate determination can be obtained to unravel associated agents of surface processes. Cosmogenic nuclide surveys on mean catchment erosion rates reveal mean basin slope as a characteristic metric in fluvially dominated landscapes. Erosion rates are shown to increase linearly until a certain point, where slope becomes highly independent of erosion rates. In such landscapes the rate of denudation will be determined by the frequency and magnitude of landsliding controlled by the rate of channel incision. In glacial sculptured landscapes such as the European Alps key basin metrics (relief, slope, channel steepness index) show no significant correlation with erosion rates except mean altitude. Terrain is set into a oversteepend, near threshold stage by processes of glacial erosion. We show that fluvial incision is largest where glacial occupation time was lowest during a glacial cycle and argue that both (mean altitude and fluvial incision) reflect the intensity of glacial occupation on the landscape. While the high Alps have a multiple glaciation history, the lower parts are only affected by glacial maxima. Glacial erosion is lower and basins had a longer time to fluvially readapt. In the oversteepend Alps fluvial incision is counteracted by landsliding and mainly depended on rock strength: We postulate that the varying hillslope angles after glacial retreat are the result of varying rock strength. We further show that measuring the incision depth as well as the drainage density can be used to quantify erosion rates and to make statements on the dependence of glacial occupation and rock strength. PALEOCLIMATIC RECORDS OF QUATERNARY TUFA IN THE SERRA DO ANDRÉ LOPES KARST, SOUTHEASTERN BRAZIL William Sallun Filho. Geological Institute, Brazil E-mail address: [email protected]
The Serra do André Lopes is a karst area situated in a dolomite plateau with a superhumid subtropical climate in the Ribeira de Iguape River valley, in the south of the State of São Paulo. It has tufa deposits in the form of waterfalls and dams. Gastropod shells and tufas were dated by 14C AMS and calibrated with SHCal04 (McCormac et al., 2004). Studies were made of two deposits in the form of paleo-waterfalls found on hillsides. At the location of Sapatú, stratified friable tufas, with irregular to plane-parallel layering, comprise various temporally repeated sequences with an apparent thickness of more than 12 meters. They are composed of