Page 1. Danmarks Miljøundersøgelser Miljøministeriet Habitatmodellering i Ledreborg Å Effekten på... more Page 1. Danmarks Miljøundersøgelser Miljøministeriet Habitatmodellering i Ledreborg Å Effekten på ørred ved reduceret vandføring Faglig rapport fra DMU, nr. 580 Page 2. [Tom side] Page 3. Danmarks Miljøundersøgelser Miljøministeriet Habitatmodellering i Ledreborg Å ...
Measurements of denitrification enzyme activity (DEA) were made in riparian zones within 27 subca... more Measurements of denitrification enzyme activity (DEA) were made in riparian zones within 27 subcatchments of a 114 km2 catchment in Denmark during summer 1996, and the rates were related to the hydrological regime of the subcatchments. The hydrological regime was characterized spatially by the specific mean flow (QMEAN) and the baseflow index (BFI), which were almost linearly related. DEA was significantly higher in the top 50 cm soil samples compared with the samples taken from between 50 and 100 cm depth. DEA and BFI were found to be weakly related with higher DEA rates in upstream subcatchments where QMEAN
Groundwater and surface water interact throughout the landscape, as depicted in the adjacent draw... more Groundwater and surface water interact throughout the landscape, as depicted in the adjacent drawing. The conceptual landscape shows, in a simplified way, groundwater interaction with all types of surface water, such as streams, lakes, and wetlands, in many different terrains, from the mountains to the oceans. Why is it important? The Bay Area is highly urbanized and is affected by the impacts from commercial, industrial, and residential development, including wastewater and industrial discharges, historic loss of wetlands, stream modification for flood control and urban development, and surface water and groundwater pollution from industrial solvents, petroleum hydrocarbons, pesticides, and legacy pollutants like mercury and PCBs. The Region has seen an expansion of residential development in the past twenty years, leading to the covering of natural recharge areas, greater storm water runoff, and alteration of stream channels and riparian zones. At the same time, water quality in rural areas is threatened by over-grazing, excess agricultural fertilizer and pesticides use, confined animal facilities, and expansion of sewage and septic systems. Historically, regulatory agencies have dealt with these issues through separate groundwater and surface water programs-a compartmentalized approach that often lacks important communication and coordination. Increased awareness of groundwater and surface water interactions can lead to improved water quality in the Bay Region. Integration of groundwater and surface water programs can help avoid problems that arise from managing one resource at the expense of the other particularly as solutions for better storm water management and TMDL attainment are sought.
The present invention relates to a human angiotensin II type 1 receptor protein, a recombinant DN... more The present invention relates to a human angiotensin II type 1 receptor protein, a recombinant DNA containing a gene which codes for said protein, a transformant carrying said DNA, production of said protein, and anti-angiotensin II substance screening methods using said transformant containing said protein.
Procedures to estimate low flow statistics at ungauged sites and their relation to hydrogeology a... more Procedures to estimate low flow statistics at ungauged sites and their relation to hydrogeology are presented. The discussion is based on an example of a Danish chalk catchment of 242 kmz, within which the climatic variation is small com- pared to the physiographical variation. The spatial and temporal variation of streaniflow was studied using synchronous discharge measurements and the application of a numerical model. The synchronous discharge measurements showed the runoff is unequally distributed within the catchment and depends primarily on the regional hydrogeology, but also on the lithology of the valley deposits. The numerical model was used to obtain an understanding of the hydrogeological effect on the temporal variation of the runoff from small sub- catchments. This was not possible from the discharge measurements because of the high uncertainty of estimating the difference in flow between two nearby gauging stations. The temporal variation was found to be strongly relate...
In this paper we investigate similarities in streamflow variables, identify groups of variables t... more In this paper we investigate similarities in streamflow variables, identify groups of variables that represent different aspects of the flow regime, and we discuss the ecological relevance of these groups. For the study we used 35 flow variables for 62 New Zealand perennial rivers, which cover a wide range of flow regimes. All flow variables were calculated using daily mean
The streamflow recession for two Danish streams is found not to follow the traditionally used sin... more The streamflow recession for two Danish streams is found not to follow the traditionally used single exponential expression Q= Q0Kt, where K is the recession constant. Three alternative equations, based on a simple hydrogeologic model, are applied. A good fit is obtained by use of the equation Q = B + C Kt, where K is a constant for each catchment and B and C are constants within each recession. Recessions with constant evapotranspiration are used to determine some of the hydraulic parameters for one of the two catchments.
The objective of this paper is to determine the most appropriate data collection strategy and ana... more The objective of this paper is to determine the most appropriate data collection strategy and analysis techniques which should be used to assess the low flow regime of a catchment. The data used were: a) synchronous discharge measurements during low flow periods, and b) continuous daily flow records. The analyses based on both types of data were able to distinguish different low flow regimes within a 114 km2 Danish catchment. Despite the limited spatial variation in climate and geomorphology there was a high spatial variability in low flows caused by differences in the lithology of sediments. This demonstrates the difficulties in using simple indices of catchment geology in regional low flow estimation. The results highlight the benefits of using synchronous discharge measurements, both for estimating low flows at ungauged sites, and for understanding groundwater flow paths. Analyses of daily flow records from six gauging stations in the catchment showed that a baseflow index was more useful than the flow duration curve for classifying low flow regimes when only short records were available. The paper illustrates the importance of estimating the uncertainty of discharge measurements when interpreting low flow data.
A two-dimensional numerical groundwater model was applied to the Lambourn catchment in the UK to ... more A two-dimensional numerical groundwater model was applied to the Lambourn catchment in the UK to predict the impact of ground water abstraction on low river flows for a representative Chalk catch ment. The calibration of the model using observed streamflow and groundwater data is described. A range of abstraction scenarios was simulated to estimate the impact of long term abstraction on monthly river flows as a function of the abstraction rate, seasonality and location. Relationships between low flow statistics and abstraction regimes were derived by analysing a number of simulated hydrographs.
A streamflow recession formula for natural basins is derived by linear hydrologic routing of the ... more A streamflow recession formula for natural basins is derived by linear hydrologic routing of the sum of inflows from discrete, independent water storages through a channel storage. Water storages include depression, detention, snow and ice, channel bank, aquifer and cavern. Evapotranspiration is incorporated in the recession formula, but seasonal effects and basin wetness and storage conditions before storms are not considered. Data from seven basins involving 156 precipitation-free recessions are used to test the performance of two-and three-parameter approximations to the theoretical recession formula. Recessions are defined to last at least 2 weeks and to begin 2 days after the peak of a basin outflow hydrograph, or at a point on the falling limb 2 days after any precipitation occurs. Recessions end when precipitation recommences, or when daily flow data stop decreasing. An inverse square formula explains most variance in the two-parameter case, in contrast to the simple exponential formula usually recommended for recession modelling. With three parameters, equally good performance is shown by formulae involving a constant plus an inverse square, or inverse cubic, or simple exponential term. These theoretically based formulae should be useful at basin scale for interpolating or extrapolating recession data, particularly in basins where little is known about water storage behaviour.
The threshold level approach is used to define drought characteristics, i.e. drought duration and... more The threshold level approach is used to define drought characteristics, i.e. drought duration and deficit volume from time series of daily streamflow. Three different procedures for pooling dependent droughts are compared: a method based on an inter-event time and volume criterion (IC), a moving average procedure (MA), and a method based on the sequent peak algorithm (SPA). The extreme values of drought duration and deficit volume are analysed using both an annual maximum series (AMS) and a partial duration series (PDS) approach. Two Danish catchments with very different flow regimes were used in the study. The IC and MA methods provided virtually the same sample statistics of the AMS of drought duration and deficit volume for all thresholds considered. The results of the SPA method differed significantly from the other two methods for high thresholds due to the presence of multi-year droughts. For analysis of seasonal droughts the SPA method is restricted to low thresholds. The occurrence of a large number of zerodrought years for low thresholds may significantly reduce the information content of the AMS, and in this case the PDS model is superior. The problem of minor droughts in the PDS was implicitly reduced by using the MA and SPA methods, and in this respect these methods have an important advantage as compared to the IC method.
1. The hydrological regime is important to the distribution of benthic organisms in streams. The ... more 1. The hydrological regime is important to the distribution of benthic organisms in streams. The objective of this study was to identify relationships between hydrological variables, describing the flow regime, and macrophyte cover, species richness, diversity and community composition in Danish lowland streams. 2. We quantified macrophyte vegetation in 44 Danish streams during summer by cover, species richness and diversity. Flow regime was characterized by 18 non-intercorrelated variables describing magnitude, frequency and duration of low and high flow events, timing or predictability of flow and general flow variability. 3. We found support in the stepwise multiple regressions analysis for our expectation that macrophyte cover is lowest in streams with high flow variability and highest in streams with long duration of low flow and low flow variability. We found support for the intermediate disturbance hypothesis as there were significant quadratic relationships between species richness and diversity as functions of disturbance frequency. There was poor discrimination in a detrended correspondence analysis (DCA) analysis of macrophyte community composition between four T W IN SP A N T W IN SP A N groups separating streams with different hydrological properties. Moreover, we did not find any relationship between the presence of disturbance-tolerant species and hydrological disturbance, suggesting that plant community composition developed independently of stream hydrology.
The objective of this study was to identify the most ecologically relevant hydrological indices f... more The objective of this study was to identify the most ecologically relevant hydrological indices for characterizing hydrological regimes in New Zealand streams. To do this we related measures of periphyton chlorophyll a, ash-free dry mass (AFDM), species richness, and diversity and invertebrate density, species richness and diversity, to thirty-four hydrological variables derived from daily flow records at eighty-three sites. The hydrological variables included some describing average flow conditions, flow variability, floods, and low-flow characteristics. 2. A principal components analysis showed that the interrelationship between many of the hydrological variables was high, and most variables correlated significantly with Principal Component 1 (PC1). The flood frequency variables formed a distinct component of the flow regime and were the main contributor to PC2. 3. We found that both the average flow conditions and some measure of variability were significantly related to most of the biological variables, and these individual hydrological variables were more strongly correlated to the biological measures than the composite principal components. Only four of the thirty-four flow variables were significantly correlated (P Ͻ 0.05) with measures of periphyton biomass (chlorophyll a and AFDM), whereas twenty-four variables were correlated with periphyton diversity. Conversely, thirty-one of the thirty-four flow variables were correlated with total invertebrate density, whereas only four variables correlated with diversity. 4. We selected the flood frequency (FRE 3), where a flood is defined as flows higher than three times the median flow, as the most ecological useful overall flow variable in New Zealand streams because it explained a significant amount of the variance in four out of the six main benthic community measures, and it had a clear mechanism of control of the biota which was commensurate with current stream ecosystem theory. Periphyton biomass decreased with increasing FRE 3 , whereas invertebrate density had an increasing/curvilinear relationship with FRE 3. Periphyton species richness and diversity decreased with increasing FRE 3 .
Page 1. Danmarks Miljøundersøgelser Miljøministeriet Habitatmodellering i Ledreborg Å Effekten på... more Page 1. Danmarks Miljøundersøgelser Miljøministeriet Habitatmodellering i Ledreborg Å Effekten på ørred ved reduceret vandføring Faglig rapport fra DMU, nr. 580 Page 2. [Tom side] Page 3. Danmarks Miljøundersøgelser Miljøministeriet Habitatmodellering i Ledreborg Å ...
Measurements of denitrification enzyme activity (DEA) were made in riparian zones within 27 subca... more Measurements of denitrification enzyme activity (DEA) were made in riparian zones within 27 subcatchments of a 114 km2 catchment in Denmark during summer 1996, and the rates were related to the hydrological regime of the subcatchments. The hydrological regime was characterized spatially by the specific mean flow (QMEAN) and the baseflow index (BFI), which were almost linearly related. DEA was significantly higher in the top 50 cm soil samples compared with the samples taken from between 50 and 100 cm depth. DEA and BFI were found to be weakly related with higher DEA rates in upstream subcatchments where QMEAN
Groundwater and surface water interact throughout the landscape, as depicted in the adjacent draw... more Groundwater and surface water interact throughout the landscape, as depicted in the adjacent drawing. The conceptual landscape shows, in a simplified way, groundwater interaction with all types of surface water, such as streams, lakes, and wetlands, in many different terrains, from the mountains to the oceans. Why is it important? The Bay Area is highly urbanized and is affected by the impacts from commercial, industrial, and residential development, including wastewater and industrial discharges, historic loss of wetlands, stream modification for flood control and urban development, and surface water and groundwater pollution from industrial solvents, petroleum hydrocarbons, pesticides, and legacy pollutants like mercury and PCBs. The Region has seen an expansion of residential development in the past twenty years, leading to the covering of natural recharge areas, greater storm water runoff, and alteration of stream channels and riparian zones. At the same time, water quality in rural areas is threatened by over-grazing, excess agricultural fertilizer and pesticides use, confined animal facilities, and expansion of sewage and septic systems. Historically, regulatory agencies have dealt with these issues through separate groundwater and surface water programs-a compartmentalized approach that often lacks important communication and coordination. Increased awareness of groundwater and surface water interactions can lead to improved water quality in the Bay Region. Integration of groundwater and surface water programs can help avoid problems that arise from managing one resource at the expense of the other particularly as solutions for better storm water management and TMDL attainment are sought.
The present invention relates to a human angiotensin II type 1 receptor protein, a recombinant DN... more The present invention relates to a human angiotensin II type 1 receptor protein, a recombinant DNA containing a gene which codes for said protein, a transformant carrying said DNA, production of said protein, and anti-angiotensin II substance screening methods using said transformant containing said protein.
Procedures to estimate low flow statistics at ungauged sites and their relation to hydrogeology a... more Procedures to estimate low flow statistics at ungauged sites and their relation to hydrogeology are presented. The discussion is based on an example of a Danish chalk catchment of 242 kmz, within which the climatic variation is small com- pared to the physiographical variation. The spatial and temporal variation of streaniflow was studied using synchronous discharge measurements and the application of a numerical model. The synchronous discharge measurements showed the runoff is unequally distributed within the catchment and depends primarily on the regional hydrogeology, but also on the lithology of the valley deposits. The numerical model was used to obtain an understanding of the hydrogeological effect on the temporal variation of the runoff from small sub- catchments. This was not possible from the discharge measurements because of the high uncertainty of estimating the difference in flow between two nearby gauging stations. The temporal variation was found to be strongly relate...
In this paper we investigate similarities in streamflow variables, identify groups of variables t... more In this paper we investigate similarities in streamflow variables, identify groups of variables that represent different aspects of the flow regime, and we discuss the ecological relevance of these groups. For the study we used 35 flow variables for 62 New Zealand perennial rivers, which cover a wide range of flow regimes. All flow variables were calculated using daily mean
The streamflow recession for two Danish streams is found not to follow the traditionally used sin... more The streamflow recession for two Danish streams is found not to follow the traditionally used single exponential expression Q= Q0Kt, where K is the recession constant. Three alternative equations, based on a simple hydrogeologic model, are applied. A good fit is obtained by use of the equation Q = B + C Kt, where K is a constant for each catchment and B and C are constants within each recession. Recessions with constant evapotranspiration are used to determine some of the hydraulic parameters for one of the two catchments.
The objective of this paper is to determine the most appropriate data collection strategy and ana... more The objective of this paper is to determine the most appropriate data collection strategy and analysis techniques which should be used to assess the low flow regime of a catchment. The data used were: a) synchronous discharge measurements during low flow periods, and b) continuous daily flow records. The analyses based on both types of data were able to distinguish different low flow regimes within a 114 km2 Danish catchment. Despite the limited spatial variation in climate and geomorphology there was a high spatial variability in low flows caused by differences in the lithology of sediments. This demonstrates the difficulties in using simple indices of catchment geology in regional low flow estimation. The results highlight the benefits of using synchronous discharge measurements, both for estimating low flows at ungauged sites, and for understanding groundwater flow paths. Analyses of daily flow records from six gauging stations in the catchment showed that a baseflow index was more useful than the flow duration curve for classifying low flow regimes when only short records were available. The paper illustrates the importance of estimating the uncertainty of discharge measurements when interpreting low flow data.
A two-dimensional numerical groundwater model was applied to the Lambourn catchment in the UK to ... more A two-dimensional numerical groundwater model was applied to the Lambourn catchment in the UK to predict the impact of ground water abstraction on low river flows for a representative Chalk catch ment. The calibration of the model using observed streamflow and groundwater data is described. A range of abstraction scenarios was simulated to estimate the impact of long term abstraction on monthly river flows as a function of the abstraction rate, seasonality and location. Relationships between low flow statistics and abstraction regimes were derived by analysing a number of simulated hydrographs.
A streamflow recession formula for natural basins is derived by linear hydrologic routing of the ... more A streamflow recession formula for natural basins is derived by linear hydrologic routing of the sum of inflows from discrete, independent water storages through a channel storage. Water storages include depression, detention, snow and ice, channel bank, aquifer and cavern. Evapotranspiration is incorporated in the recession formula, but seasonal effects and basin wetness and storage conditions before storms are not considered. Data from seven basins involving 156 precipitation-free recessions are used to test the performance of two-and three-parameter approximations to the theoretical recession formula. Recessions are defined to last at least 2 weeks and to begin 2 days after the peak of a basin outflow hydrograph, or at a point on the falling limb 2 days after any precipitation occurs. Recessions end when precipitation recommences, or when daily flow data stop decreasing. An inverse square formula explains most variance in the two-parameter case, in contrast to the simple exponential formula usually recommended for recession modelling. With three parameters, equally good performance is shown by formulae involving a constant plus an inverse square, or inverse cubic, or simple exponential term. These theoretically based formulae should be useful at basin scale for interpolating or extrapolating recession data, particularly in basins where little is known about water storage behaviour.
The threshold level approach is used to define drought characteristics, i.e. drought duration and... more The threshold level approach is used to define drought characteristics, i.e. drought duration and deficit volume from time series of daily streamflow. Three different procedures for pooling dependent droughts are compared: a method based on an inter-event time and volume criterion (IC), a moving average procedure (MA), and a method based on the sequent peak algorithm (SPA). The extreme values of drought duration and deficit volume are analysed using both an annual maximum series (AMS) and a partial duration series (PDS) approach. Two Danish catchments with very different flow regimes were used in the study. The IC and MA methods provided virtually the same sample statistics of the AMS of drought duration and deficit volume for all thresholds considered. The results of the SPA method differed significantly from the other two methods for high thresholds due to the presence of multi-year droughts. For analysis of seasonal droughts the SPA method is restricted to low thresholds. The occurrence of a large number of zerodrought years for low thresholds may significantly reduce the information content of the AMS, and in this case the PDS model is superior. The problem of minor droughts in the PDS was implicitly reduced by using the MA and SPA methods, and in this respect these methods have an important advantage as compared to the IC method.
1. The hydrological regime is important to the distribution of benthic organisms in streams. The ... more 1. The hydrological regime is important to the distribution of benthic organisms in streams. The objective of this study was to identify relationships between hydrological variables, describing the flow regime, and macrophyte cover, species richness, diversity and community composition in Danish lowland streams. 2. We quantified macrophyte vegetation in 44 Danish streams during summer by cover, species richness and diversity. Flow regime was characterized by 18 non-intercorrelated variables describing magnitude, frequency and duration of low and high flow events, timing or predictability of flow and general flow variability. 3. We found support in the stepwise multiple regressions analysis for our expectation that macrophyte cover is lowest in streams with high flow variability and highest in streams with long duration of low flow and low flow variability. We found support for the intermediate disturbance hypothesis as there were significant quadratic relationships between species richness and diversity as functions of disturbance frequency. There was poor discrimination in a detrended correspondence analysis (DCA) analysis of macrophyte community composition between four T W IN SP A N T W IN SP A N groups separating streams with different hydrological properties. Moreover, we did not find any relationship between the presence of disturbance-tolerant species and hydrological disturbance, suggesting that plant community composition developed independently of stream hydrology.
The objective of this study was to identify the most ecologically relevant hydrological indices f... more The objective of this study was to identify the most ecologically relevant hydrological indices for characterizing hydrological regimes in New Zealand streams. To do this we related measures of periphyton chlorophyll a, ash-free dry mass (AFDM), species richness, and diversity and invertebrate density, species richness and diversity, to thirty-four hydrological variables derived from daily flow records at eighty-three sites. The hydrological variables included some describing average flow conditions, flow variability, floods, and low-flow characteristics. 2. A principal components analysis showed that the interrelationship between many of the hydrological variables was high, and most variables correlated significantly with Principal Component 1 (PC1). The flood frequency variables formed a distinct component of the flow regime and were the main contributor to PC2. 3. We found that both the average flow conditions and some measure of variability were significantly related to most of the biological variables, and these individual hydrological variables were more strongly correlated to the biological measures than the composite principal components. Only four of the thirty-four flow variables were significantly correlated (P Ͻ 0.05) with measures of periphyton biomass (chlorophyll a and AFDM), whereas twenty-four variables were correlated with periphyton diversity. Conversely, thirty-one of the thirty-four flow variables were correlated with total invertebrate density, whereas only four variables correlated with diversity. 4. We selected the flood frequency (FRE 3), where a flood is defined as flows higher than three times the median flow, as the most ecological useful overall flow variable in New Zealand streams because it explained a significant amount of the variance in four out of the six main benthic community measures, and it had a clear mechanism of control of the biota which was commensurate with current stream ecosystem theory. Periphyton biomass decreased with increasing FRE 3 , whereas invertebrate density had an increasing/curvilinear relationship with FRE 3. Periphyton species richness and diversity decreased with increasing FRE 3 .
Uploads
Papers by Bente Clausen