The survival of one of Europe's most important Mesolithic sites, Star Carr, has been threaten... more The survival of one of Europe's most important Mesolithic sites, Star Carr, has been threatened owing to recent changes in its hydrology and associated changes in groundwater geochemistry. Before this study it was unclear what was controlling these changes, but possible causes were changes in precipitation regime (notably the frequency of drought), changes in groundwater abstraction, recent agricultural drainage or a combination of these factors. This paper evaluates the hydrology of Star Carr and its environs within the River Hertford sub-catchment of the River Derwent. Available hydrological data (precipitation, evapotranspiration, river flow and groundwater levels) were collated and used to characterise the River Hertford catchment and provide a hydrological and hydrogeological context for the site. The data were augmented by the insertion of 12 dipwells into the site which were used for both site monitoring and model testing. The monitoring included water abstraction for iso...
International Mine Water Association Symposium: Mine Water and Environmental Impacts, 1998
Where the host rock for a mineral deposit is of low permeability, the inflows to a mine from surf... more Where the host rock for a mineral deposit is of low permeability, the inflows to a mine from surface waters may represent a significant portion of the total inflow. This scenario is particularly pertinent where shallow mining has taken place close to a surface water course and the mining activity has enhanced fracture permeability allowing increased infiltration of surface waters. In extreme cases this can cause the affected streams to flow only ephemerally. This situation impacts upon both the mine, through increased nuisance and pumping costs, and the local environment though loss of habitat.
The Olympias Mine in north-east Greece worked a mixed sulphide ore body of lead and zinc from 1970 to 1992 at depths of 100 to 300 metres below ground. The ore body is hosted in Lower Palaeozoic meta-sediments, principally low permeability gneisses and schists. During the late 1980’s block caving was the mining method used and this caused surface subsidence adjacent to the course of an overlying stream, the Basdekilakkos Creek. This subsidence led to increased infiltration from the creek which now dries up during summer months in the vicinity of the mine.
Since 1995 the mine has been re-examined as a potential gold project and Steffen, Robertson & Kirsten (UK) Ltd (SRK) were appointed as consultants for mine water management as part of an overall feasibility study. The objectives were to design and cost the infrastructure requirements for mine water management for the future life of the mine. This required an assessment of the future inflows and the nuisance caused by background inflows and the perceived risk of sudden large volume (catastrophic) inflows.
SRK designed and implemented a monitoring network to identify the surface water component of background inflows and carried out a cost-benefit analysis to asses the feasibility of potential remediation strategies. Additionally, using available geological and mining records combined with geotechnical assessment and underground hydraulic testing, SRK established that the risk of catastrophic inflows is low.
This paper describes the spatial and temporal pattern of groundwater flow accretion to the River ... more This paper describes the spatial and temporal pattern of groundwater flow accretion to the River Lambourn, a 234 km2 chalk catchment of the West Berkshire Downs, UK, which has been largely unaffected by groundwater abstraction. Variations in the discharge measured at four fixed gauges in the catchment, coupled with information on the length of flowing channel over the period 1983–2001, are used to describe regional patterns in flow accretion. Mean catchment accretion generally exceeds 0·15 m3 s−1 km−1, but there are significant differences between perennial reaches indicating how the combination of local structural controls and seasonal changes in the drainage net affect flow accretion. Data from current meter surveys were used to determine the spatial variability in flow accretion: 505 paired observations along 12 reaches between 1 and 2·95 km in length indicated a consistent spatial trend in accretion. Accretion was high in upstream and downstream channel reaches, and in middle reaches where dry valleys intersected the main valley. A flow accretion index was developed to describe the relationship of flow accretion in each of the 12 study reaches to catchment discharge. The relationship varied from a strong positive correlation with catchment discharge (two reaches), a weak positive correlation (three reaches), a strong negative correlation (two reaches), to no relationship to catchment discharge (four reaches). The results highlight the need to reconsider the usual assumption of uniform, or uniformly increasing, flow accretion in chalk catchments. Moreover, they emphasize the importance of catchment topography, and illustrate how flow accretion in individual reaches may vary between high and low groundwater levels.
Variations in floodplain channel water levels and valley floor groundwater levels (measured in pi... more Variations in floodplain channel water levels and valley floor groundwater levels (measured in piezometers and boreholes) are examined at selected points along the course of the River Lambourn, a chalk river in southern England. A local alluvial gravel aquifer in the valley bottom is associated with numerous small wetlands that extend over much of the river's perennial profile. Variations in hydraulic gradient between local borehole levels and/or floodplain channel water levels are described for three sites in the seasonal section of the channel at Bockhampton, East Garston and West Shefford. The results indicate that observed groundwater levels are closely associated with flows from discrete springs at the margins of the channel and floodplain. However, as the floodplain widens and the alluvial gravel aquifer increases in size, the gravel aquifer accounts for a substantial down-valley component of groundwater flow with a diffuse vertical water flux. In the lower catchment, the exchange of flows between the gravel aquifer and the river enables some attenuation of floodplain water-table variability, providing a stable hydrological regime for valley-bottom wetlands. Catchment controls upon the local, valley-bottom, wetland regime are demonstrated with the application of a simple groundwater model developed using MODFLOW. The model is used to simulate groundwater discharge to the river in the upper and lower catchment, in addition to the water level regime at selected points in the valley bottom in the lower catchment. The results demonstrate the importance of taking catchment-scale water flow into account when managing isolated wetlands in a permeable catchment.
The survival of one of Europe's most important Mesolithic sites, Star Carr, has been threaten... more The survival of one of Europe's most important Mesolithic sites, Star Carr, has been threatened owing to recent changes in its hydrology and associated changes in groundwater geochemistry. Before this study it was unclear what was controlling these changes, but possible causes were changes in precipitation regime (notably the frequency of drought), changes in groundwater abstraction, recent agricultural drainage or a combination of these factors. This paper evaluates the hydrology of Star Carr and its environs within the River Hertford sub-catchment of the River Derwent. Available hydrological data (precipitation, evapotranspiration, river flow and groundwater levels) were collated and used to characterise the River Hertford catchment and provide a hydrological and hydrogeological context for the site. The data were augmented by the insertion of 12 dipwells into the site which were used for both site monitoring and model testing. The monitoring included water abstraction for iso...
The survival of one of Europe's most important Mesolithic sites, Star Carr, has been threaten... more The survival of one of Europe's most important Mesolithic sites, Star Carr, has been threatened owing to recent changes in its hydrology and associated changes in groundwater geochemistry. Before this study it was unclear what was controlling these changes, but possible causes were changes in precipitation regime (notably the frequency of drought), changes in groundwater abstraction, recent agricultural drainage or a combination of these factors. This paper evaluates the hydrology of Star Carr and its environs within the River Hertford sub-catchment of the River Derwent. Available hydrological data (precipitation, evapotranspiration, river flow and groundwater levels) were collated and used to characterise the River Hertford catchment and provide a hydrological and hydrogeological context for the site. The data were augmented by the insertion of 12 dipwells into the site which were used for both site monitoring and model testing. The monitoring included water abstraction for iso...
International Mine Water Association Symposium: Mine Water and Environmental Impacts, 1998
Where the host rock for a mineral deposit is of low permeability, the inflows to a mine from surf... more Where the host rock for a mineral deposit is of low permeability, the inflows to a mine from surface waters may represent a significant portion of the total inflow. This scenario is particularly pertinent where shallow mining has taken place close to a surface water course and the mining activity has enhanced fracture permeability allowing increased infiltration of surface waters. In extreme cases this can cause the affected streams to flow only ephemerally. This situation impacts upon both the mine, through increased nuisance and pumping costs, and the local environment though loss of habitat.
The Olympias Mine in north-east Greece worked a mixed sulphide ore body of lead and zinc from 1970 to 1992 at depths of 100 to 300 metres below ground. The ore body is hosted in Lower Palaeozoic meta-sediments, principally low permeability gneisses and schists. During the late 1980’s block caving was the mining method used and this caused surface subsidence adjacent to the course of an overlying stream, the Basdekilakkos Creek. This subsidence led to increased infiltration from the creek which now dries up during summer months in the vicinity of the mine.
Since 1995 the mine has been re-examined as a potential gold project and Steffen, Robertson & Kirsten (UK) Ltd (SRK) were appointed as consultants for mine water management as part of an overall feasibility study. The objectives were to design and cost the infrastructure requirements for mine water management for the future life of the mine. This required an assessment of the future inflows and the nuisance caused by background inflows and the perceived risk of sudden large volume (catastrophic) inflows.
SRK designed and implemented a monitoring network to identify the surface water component of background inflows and carried out a cost-benefit analysis to asses the feasibility of potential remediation strategies. Additionally, using available geological and mining records combined with geotechnical assessment and underground hydraulic testing, SRK established that the risk of catastrophic inflows is low.
This paper describes the spatial and temporal pattern of groundwater flow accretion to the River ... more This paper describes the spatial and temporal pattern of groundwater flow accretion to the River Lambourn, a 234 km2 chalk catchment of the West Berkshire Downs, UK, which has been largely unaffected by groundwater abstraction. Variations in the discharge measured at four fixed gauges in the catchment, coupled with information on the length of flowing channel over the period 1983–2001, are used to describe regional patterns in flow accretion. Mean catchment accretion generally exceeds 0·15 m3 s−1 km−1, but there are significant differences between perennial reaches indicating how the combination of local structural controls and seasonal changes in the drainage net affect flow accretion. Data from current meter surveys were used to determine the spatial variability in flow accretion: 505 paired observations along 12 reaches between 1 and 2·95 km in length indicated a consistent spatial trend in accretion. Accretion was high in upstream and downstream channel reaches, and in middle reaches where dry valleys intersected the main valley. A flow accretion index was developed to describe the relationship of flow accretion in each of the 12 study reaches to catchment discharge. The relationship varied from a strong positive correlation with catchment discharge (two reaches), a weak positive correlation (three reaches), a strong negative correlation (two reaches), to no relationship to catchment discharge (four reaches). The results highlight the need to reconsider the usual assumption of uniform, or uniformly increasing, flow accretion in chalk catchments. Moreover, they emphasize the importance of catchment topography, and illustrate how flow accretion in individual reaches may vary between high and low groundwater levels.
Variations in floodplain channel water levels and valley floor groundwater levels (measured in pi... more Variations in floodplain channel water levels and valley floor groundwater levels (measured in piezometers and boreholes) are examined at selected points along the course of the River Lambourn, a chalk river in southern England. A local alluvial gravel aquifer in the valley bottom is associated with numerous small wetlands that extend over much of the river's perennial profile. Variations in hydraulic gradient between local borehole levels and/or floodplain channel water levels are described for three sites in the seasonal section of the channel at Bockhampton, East Garston and West Shefford. The results indicate that observed groundwater levels are closely associated with flows from discrete springs at the margins of the channel and floodplain. However, as the floodplain widens and the alluvial gravel aquifer increases in size, the gravel aquifer accounts for a substantial down-valley component of groundwater flow with a diffuse vertical water flux. In the lower catchment, the exchange of flows between the gravel aquifer and the river enables some attenuation of floodplain water-table variability, providing a stable hydrological regime for valley-bottom wetlands. Catchment controls upon the local, valley-bottom, wetland regime are demonstrated with the application of a simple groundwater model developed using MODFLOW. The model is used to simulate groundwater discharge to the river in the upper and lower catchment, in addition to the water level regime at selected points in the valley bottom in the lower catchment. The results demonstrate the importance of taking catchment-scale water flow into account when managing isolated wetlands in a permeable catchment.
The survival of one of Europe's most important Mesolithic sites, Star Carr, has been threaten... more The survival of one of Europe's most important Mesolithic sites, Star Carr, has been threatened owing to recent changes in its hydrology and associated changes in groundwater geochemistry. Before this study it was unclear what was controlling these changes, but possible causes were changes in precipitation regime (notably the frequency of drought), changes in groundwater abstraction, recent agricultural drainage or a combination of these factors. This paper evaluates the hydrology of Star Carr and its environs within the River Hertford sub-catchment of the River Derwent. Available hydrological data (precipitation, evapotranspiration, river flow and groundwater levels) were collated and used to characterise the River Hertford catchment and provide a hydrological and hydrogeological context for the site. The data were augmented by the insertion of 12 dipwells into the site which were used for both site monitoring and model testing. The monitoring included water abstraction for iso...
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The Olympias Mine in north-east Greece worked a mixed sulphide ore body of lead and zinc from 1970 to 1992 at depths of 100 to 300 metres below ground. The ore body is hosted in Lower Palaeozoic meta-sediments, principally low permeability gneisses and schists. During the late 1980’s block caving was the mining method used and this caused surface subsidence adjacent to the course of an overlying stream, the Basdekilakkos Creek. This subsidence led to increased infiltration from the creek which now dries up during summer months in the vicinity of the mine.
Since 1995 the mine has been re-examined as a potential gold project and Steffen, Robertson & Kirsten (UK) Ltd (SRK) were appointed as consultants for mine water management as part of an overall feasibility study. The objectives were to design and cost the infrastructure requirements for mine water management for the future life of the mine. This required an assessment of the future inflows and the nuisance caused by background inflows and the perceived risk of sudden large volume (catastrophic) inflows.
SRK designed and implemented a monitoring network to identify the surface water component of background inflows and carried out a cost-benefit analysis to asses the feasibility of potential remediation strategies. Additionally, using available geological and mining records combined with geotechnical assessment and underground hydraulic testing, SRK established that the risk of catastrophic inflows is low.
The Olympias Mine in north-east Greece worked a mixed sulphide ore body of lead and zinc from 1970 to 1992 at depths of 100 to 300 metres below ground. The ore body is hosted in Lower Palaeozoic meta-sediments, principally low permeability gneisses and schists. During the late 1980’s block caving was the mining method used and this caused surface subsidence adjacent to the course of an overlying stream, the Basdekilakkos Creek. This subsidence led to increased infiltration from the creek which now dries up during summer months in the vicinity of the mine.
Since 1995 the mine has been re-examined as a potential gold project and Steffen, Robertson & Kirsten (UK) Ltd (SRK) were appointed as consultants for mine water management as part of an overall feasibility study. The objectives were to design and cost the infrastructure requirements for mine water management for the future life of the mine. This required an assessment of the future inflows and the nuisance caused by background inflows and the perceived risk of sudden large volume (catastrophic) inflows.
SRK designed and implemented a monitoring network to identify the surface water component of background inflows and carried out a cost-benefit analysis to asses the feasibility of potential remediation strategies. Additionally, using available geological and mining records combined with geotechnical assessment and underground hydraulic testing, SRK established that the risk of catastrophic inflows is low.