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Search Results: 1 - 10 of 138736 matches for " K. Hinsby "
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Assessing impacts of climate change, sea level rise, and drainage canals on saltwater intrusion to coastal aquifer
P. Rasmussen, T. O. Sonnenborg, G. Goncear,K. Hinsby
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2013,
Abstract: Groundwater abstraction from coastal aquifers is vulnerable to climate change and sea level rise because both may potentially impact saltwater intrusion and hence groundwater quality depending on the hydrogeological setting. In the present study the impacts of sea level rise and changes in groundwater recharge are quantified for an island located in the Western Baltic Sea. The low-lying central area of the investigated part of the island was extensively drained and reclaimed during the second half of the 19th century by a system of artificial drainage canals that significantly affects the flow dynamics of the area. The drinking water, mainly for summer cottages, is abstracted from 11 wells drilled to a depth of around 20 m into the upper 5–10 m of a confined chalk aquifer, and the total pumping is only 5–6% of the drainage pumping. Increasing chloride concentrations have been observed in several abstraction wells and in some cases the WHO drinking water standard has been exceeded. Using the modeling package MODFLOW/MT3D/SEAWAT the historical, present and future freshwater-sea water distribution is simulated. The model is calibrated against hydraulic head observations and validated against geochemical and geophysical data from new investigation wells, including borehole logs, and from an airborne transient electromagnetic survey. The impact of climate changes on saltwater intrusion is found to be sensitive to the boundary conditions of the investigated system. For the flux-controlled aquifer to the west of the drained area only changes in groundwater recharge impacts the freshwater–sea water interface whereas sea level rise does not result in increasing sea water intrusion. However, on the barrier islands to the east of the reclaimed area, below which the sea is hydraulically connected to the drainage canals, and the boundary of the flow system therefore controlled, the projected changes in sea level, groundwater recharge and stage of the drainage canals all have significant impacts on saltwater intrusion and the chloride concentrations found in abstraction wells.
Assessing impacts of climate change, sea level rise, and drainage canals on saltwater intrusion to coastal aquifer
P. Rasmussen,T. O. Sonnenborg,G. Goncear,K. Hinsby
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2013, DOI: 10.5194/hess-17-421-2013
Abstract: Groundwater abstraction from coastal aquifers is vulnerable to climate change and sea level rise because both may potentially impact saltwater intrusion and hence groundwater quality depending on the hydrogeological setting. In the present study the impacts of sea level rise and changes in groundwater recharge are quantified for an island located in the Western Baltic Sea. The low-lying central area of the investigated part of the island was extensively drained and reclaimed during the second half of the 19th century by a system of artificial drainage canals that significantly affects the flow dynamics of the area. The drinking water, mainly for summer cottages, is abstracted from 11 wells drilled to a depth of around 20 m into the upper 5–10 m of a confined chalk aquifer, and the total pumping is only 5–6% of the drainage pumping. Increasing chloride concentrations have been observed in several abstraction wells and in some cases the WHO drinking water standard has been exceeded. Using the modeling package MODFLOW/MT3D/SEAWAT the historical, present and future freshwater-sea water distribution is simulated. The model is calibrated against hydraulic head observations and validated against geochemical and geophysical data from new investigation wells, including borehole logs, and from an airborne transient electromagnetic survey. The impact of climate changes on saltwater intrusion is found to be sensitive to the boundary conditions of the investigated system. For the flux-controlled aquifer to the west of the drained area only changes in groundwater recharge impacts the freshwater–sea water interface whereas sea level rise does not result in increasing sea water intrusion. However, on the barrier islands to the east of the reclaimed area, below which the sea is hydraulically connected to the drainage canals, and the boundary of the flow system therefore controlled, the projected changes in sea level, groundwater recharge and stage of the drainage canals all have significant impacts on saltwater intrusion and the chloride concentrations found in abstraction wells.
Assessing impacts of climate change, sea level rise, and drainage canals on saltwater intrusion to coastal aquifer
P. Rasmussen,T. O. Sonnenborg,G. Goncear,K. Hinsby
Hydrology and Earth System Sciences Discussions , 2012, DOI: 10.5194/hessd-9-7969-2012
Abstract: Groundwater abstraction from coastal aquifers is vulnerable to climate change and sea level rise because both may potentially impact saltwater intrusion and hence groundwater quality depending on the hydrogeological setting. In the present study the impacts of sea level rise and changes in groundwater recharge are quantified for an island located in the Western Baltic Sea. Agricultural land dominates the western and central parts of the island, which geologically are developed as push moraine hills and a former lagoon (later wetland area) behind barrier islands to the east. The low-lying central area of the island was extensively drained and reclaimed during the second half of the 19th century. Summer cottages along the beach on the former barrier islands dominate the eastern part of the island. The main water abstraction is for holiday cottages during the summer period (June–August). The water is abstracted from 11 wells drilled to a depth of around 20 m in the upper 5–10 m of a confined chalk aquifer. Increasing chloride concentrations have been observed in several abstraction wells and in some cases the WHO drinking water standard has been exceeded. Using the modeling package MODFLOW/MT3D/SEAWAT the historical, present and future freshwater–sea water distribution is simulated. The model is calibrated against hydraulic head observations and validated against geochemical and geophysical data from new investigation wells, including borehole logs, and from an airborne transient electromagnetic survey. The impact of climate changes on saltwater intrusion is found to be sensitive to the boundary conditions of the investigated system. For the flux-controlled aquifer to the west of the drained area only changes in groundwater recharge impacts the freshwater–sea water interface whereas sea level rise do not result in increasing sea water intrusion. However, on the barrier islands to the east of the reclaimed area below which the sea is hydraulically connected to the drainage canal, and the boundary of the flow system therefore controlled, the projected changes in sea level, groundwater recharge and stage of the drainage canal all have significant impacts on saltwater intrusion and hence the chloride concentrations found in the abstraction wells.
Threshold values and management options for nutrients in a catchment of a temperate estuary with poor ecological status
K. Hinsby,S. Markager,B. Kronvang,J. Windolf
Hydrology and Earth System Sciences Discussions , 2012, DOI: 10.5194/hessd-9-2157-2012
Abstract: Intensive farming has severe impacts on the chemical status of groundwater and streams and consequently on the ecological status of dependent ecosystems. Eutrophication is a widespread problem in lakes and marine waters. Common problems are hypoxia, algal blooms and fish kills, and loss of water clarity, underwater vegetation, biodiversity, and recreational value. In this paper we evaluate the nitrogen (N) and phosphorus (P) chemistry of groundwater and surface water in a coastal catchment, the loadings and sources of N and P and their effect on the ecological status of an estuary. We calculate the necessary reductions in N and P loadings to the estuary for obtaining a good ecological status, which we define based on the number of days with N and P limitation, and the equivalent stream and groundwater threshold values assuming two different management options. The calculations are performed by the combined use of empirical models and a physically based 3-D integrated hydrological model of the whole catchment. The assessment of the ecological status indicates that the N and P loads to the investigated estuary should be reduced by a factor of 0.52 and 0.56, respectively, to restore good ecological status. Model estimates show that threshold total N concentrations should be in the range of 2.9 to 3.1 mg l 1 in inlet freshwater to Horsens Estuary and 6.0 to 9.3 mg l 1 in shallow aerobic groundwater (~27–41 mg l 1 of nitrate), depending on the management measures implemented in the catchment. The situation for total P is more complex but data indicate that groundwater threshold values are not needed. The inlet freshwater threshold value for total P to Horsens Estuary for the selected management options is 0.084 mg l 1. Regional climate models project increasing winter precipitation and runoff in the investigated region resulting in increasing runoff and nutrient loads to coastal waters if present land use and farming practices continue. Hence, lower threshold values are required in the future to ensure good status of all water bodies and ecosystems.
Threshold values and management options for nutrients in a catchment of a temperate estuary with poor ecological status
K. Hinsby, S. Markager, B. Kronvang, J. Windolf, T. O. Sonnenborg,L. Thorling
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2012,
Abstract: Intensive farming has severe impacts on the chemical status of groundwater and streams and consequently on the ecological status of dependent ecosystems. Eutrophication is a widespread problem in lakes and marine waters. Common problems are hypoxia, algal blooms, fish kills, and loss of water clarity, underwater vegetation, biodiversity and recreational value. In this paper we evaluate the nitrogen (N) and phosphorus (P) concentrations of groundwater and surface water in a coastal catchment, the loadings and sources of N and P, and their effect on the ecological status of an estuary. We calculate the necessary reductions in N and P loadings to the estuary for obtaining a good ecological status, which we define based on the number of days with N and P limitation, and the corresponding stream and groundwater threshold values assuming two different management options. The calculations are performed by the combined use of empirical models and a physically based 3-D integrated hydrological model of the whole catchment. The assessment of the ecological status indicates that the N and P loads to the investigated estuary should be reduced to levels corresponding to 52 and 56% of the current loads, respectively, to restore good ecological status. Model estimates show that threshold total N (TN) concentrations should be in the range of 2.9 to 3.1 mg l 1 in inlet freshwater (streams) to Horsens estuary and 6.0 to 9.3 mg l 1 in shallow aerobic groundwater (~ 27–41 mg l 1 of nitrate), depending on the management measures implemented in the catchment. The situation for total P (TP) is more complex, but data indicate that groundwater threshold values are not needed. The stream threshold value for TP to Horsens estuary for the selected management options is 0.084 mg l 1. Regional climate models project increasing winter precipitation and runoff in the investigated region resulting in increasing runoff and nutrient loads to the Horsens estuary and many other coastal waters if present land use and farming practices continue. Hence, lower threshold values are required in many coastal catchments in the future to ensure good status of water bodies and ecosystems.
Elevation correction of ERA-Interim temperature data in complex terrain
J. Rasmussen, T. O. Sonnenborg, S. Stisen, L. P. Seaby, B. S. B. Christensen,K. Hinsby
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2012,
Abstract: Climate changes are expected to result in a warmer global climate, with increased inter-annual variability. In this study, the possible impacts of these climate changes on irrigation and low stream flow are investigated using a distributed hydrological model of a sandy catchment in western Denmark. The IPCC climate scenario A1B was chosen as the basis for the study, and meteorological forcings (precipitation, reference evapotranspiration and temperature) derived from the ECHAM5-RACMO regional climate model for the period 2071–2100 was applied to the model. Two bias correction methods, delta change and Distribution-Based Scaling, were used to evaluate the importance of the bias correction method. Using the annual irrigation amounts, the 5-percentile stream flow, the median minimum stream flow and the mean stream flow as indicators, the irrigation and the stream flow predicted using the two methods were compared. The study found that irrigation is significantly underestimated when using the delta change method, due to the inability of this method to account for changes in inter-annual variability of precipitation and reference ET and the resulting effects on irrigation demands. However, this underestimation of irrigation did not result in a significantly higher summer stream flow, because the summer stream flow in the studied catchment is controlled by the winter and spring recharge, rather than the summer precipitation. Additionally, future increases in CO2 are found to have a significant effect on both irrigation and low flow, due to reduced transpiration from plants.
Numerical modelling of climate change impacts on freshwater lenses on the North Sea Island of Borkum using hydrological and geophysical methods
H. Sulzbacher, H. Wiederhold, B. Siemon, M. Grinat, J. Igel, T. Burschil, T. Günther,K. Hinsby
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2012,
Abstract: A numerical, density dependent groundwater model is set up for the North Sea Island of Borkum to estimate climate change impacts on coastal aquifers and especially the situation of barrier islands in the Wadden Sea. The database includes information from boreholes, a seismic survey, a helicopter-borne electromagnetic (HEM) survey, monitoring of the freshwater-saltwater boundary by vertical electrode chains in two boreholes, measurements of groundwater table, pumping and slug tests, as well as water samples. Based on a statistical analysis of borehole columns, seismic sections and HEM, a hydrogeological model is set up. The groundwater model is developed using the finite-element programme FEFLOW. The density dependent groundwater model is calibrated on the basis of hydraulic, hydrological and geophysical data, in particular spatial HEM and local monitoring data. Verification runs with the calibrated model show good agreement between measured and computed hydraulic heads. A good agreement is also obtained between measured and computed density or total dissolved solids data for both the entire freshwater lens on a large scale and in the area of the well fields on a small scale. For simulating future changes in this coastal groundwater system until the end of the current century, we use the climate scenario A2, specified by the Intergovernmental Panel on Climate Change and, in particular, the data for the German North Sea coast. Simulation runs show proceeding salinisation with time beneath the well fields of the two waterworks Waterdelle and Ostland. The modelling study shows that the spreading of well fields is an appropriate protection measure against excessive salinisation of the water supply until the end of the current century.
Transboundary geophysical mapping of geological elements and salinity distribution critical for the assessment of future sea water intrusion in response to sea level rise
F. J rgensen, W. Scheer, S. Thomsen, T. O. Sonnenborg, K. Hinsby, H. Wiederhold, C. Schamper, T. Burschil, B. Roth, R. Kirsch,E. Auken
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2012,
Abstract: Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect groundwater flow. In a study area covering 730 km2 across the border between Germany and Denmark, a combination of an airborne electromagnetic survey (performed with the SkyTEM system), a high-resolution seismic survey and borehole logging has been used in an integrated mapping of important geological, physical and chemical features of the subsurface. The spacing between flight lines is 200–250 m which gives a total of about 3200 line km. About 38 km of seismic lines have been collected. Faults bordering a graben structure, buried tunnel valleys, glaciotectonic thrust complexes, marine clay units, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt/freshwater boundary and the chemical status of groundwater. Although the westernmost part of the study area along the North Sea coast is saturated with saline water and the TEM data therefore are strongly influenced by the increased electrical conductivity there, buried valleys and other geological elements are still revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing the existence, distribution and geometry of the mapped geological elements, and their control on the groundwater salinity distribution is assessed.
Contribution of Transcriptomics to Systems-Level Understanding of Methanogenic Archaea
Patrick D. Browne,Hinsby Cadillo-Quiroz
Archaea , 2013, DOI: 10.1155/2013/586369
Abstract:
Contribution of Transcriptomics to Systems-Level Understanding of Methanogenic Archaea
Patrick D. Browne,Hinsby Cadillo-Quiroz
Archaea , 2013, DOI: 10.1155/2013/586369
Abstract: Methane-producing Archaea are of interest due to their contribution to atmospheric change and for their roles in technological applications including waste treatment and biofuel production. Although restricted to anaerobic environments, methanogens are found in a wide variety of habitats, where they commonly live in syntrophic relationships with bacterial partners. Owing to tight thermodynamic constraints of methanogenesis alone or in syntrophic metabolism, methanogens must carefully regulate their catabolic pathways including the regulation of RNA transcripts. The transcriptome is a dynamic and important control point in microbial systems. This paper assesses the impact of mRNA (transcriptome) studies on the understanding of methanogenesis with special consideration given to how methanogenesis is regulated to cope with nutrient limitation, environmental variability, and interactions with syntrophic partners. In comparison with traditional microarray-based transcriptome analyses, next-generation high-throughput RNA sequencing is greatly advantageous in assessing transcription start sites, the extent of 5′ untranslated regions, operonic structure, and the presence of small RNAs. We are still in the early stages of understanding RNA regulation but it is already clear that determinants beyond transcript abundance are highly relevant to the lifestyles of methanogens, requiring further study. 1. Introduction Methane- (CH4-) producing Archaea occupy an important position in the global carbon cycle and in atmospheric change by performing the final steps of biomass degradation in anaerobic systems, and releasing significant amounts of CH4 to the atmosphere every year [1]. Also, methanogenic Archaea are of interest due to their role in anaerobic degradation including waste treatment, biogenic gas production from coal, and other substrates that have potential for CH4 to be harvested for use as a fuel. Therefore, considerable environmental and economic benefits may come from understanding biological CH4 production. In terms of physiology, three major, partially overlapping, methanogenesis pathways are recognized: (i) methanogenesis from carbon dioxide (CO2) reduction with hydrogen (H2) (hydrogenotrophic pathway), (ii) methanogenesis from methylated compounds such as methanol and methylated amines (methylotrophic pathway), and (iii) methanogenesis from acetate cleavage (aceticlastic pathway). The biochemistry of methanogenesis was reviewed elsewhere [2–4] and is summarized in Figure 1. The only known biological producers of CH4 are a diverse range of anaerobic
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