Peak Flow Periods Research Articles

A geomorphic perspective on discharge–area relationships

AbstractIt is well‐documented that the discharge‐area power‐law scaling exponent (θ) can be much lower than 1 during peak flow periods. A physical explanation for this phenomenon is generally given with the help of the channel network width function, which represents pure surface flow (PSF). When PSF ceases to dominate, θ is expected to increase due to the increasing contribution of mixed surface sub‐surface flow (MSSF) and approach 1. However, to our knowledge, no study thus far has conducted a systematic investigation of the variation of θ. In this study, we use a channel network morphology‐based routing model that considers both PSF and MSSF to investigate the variation of θ across the streamflow spectrum. The model captures the increasing trend of θ quite well during recession periods, attributable to the growing dominance of MSSF. We also demonstrate that the analysis of the discharge‐area scaling is further complicated by several factors, including spatio‐temporal variation of rainfall. The uniqueness of the model is that it suggests θ to assume values much greater than 1 because the flow in smaller basins decreases at a higher rate during late recession periods. Demonstrating this effect using observed data is difficult since obtaining sufficiently long recession curves is practically challenging. However, the predicted trend of θ is well supported by observed data when we perform percentile‐based discharge‐area scaling analysis. Our results thus indicate the possibility that a basin is not merely a sum of its hillslopes, with far‐reaching consequences for modelling hydrological and ecological phenomena.

Ecological impact assessment of dam construction: A case study of Diamer Basha Dam Gilgit‐Baltistan, Pakistan

AbstractDam construction poses significant ecological impact, both during the initial construction phase and long after the dam is completed. The Diamer Basha Dam, situated on the River Indus in the Gilgit‐Baltistan district of Pakistan, is receiving significant attention due to the ecological consequences of the proposed and ongoing construction. The Dam is a 272‐m‐tall reservoir with a 9867.912 Mm3 (million cubic meter) capacity and will be the world's highest roller compact concrete dam. The assessment of local ecological impacts was compiled in a checklist and matrices format to discuss the impacts on the status of species diversity in the study area. Using a random sample methodology, line transects, and quadrats were employed to evaluate phytosociological properties of vegetation. The floral parameters recorded were percent cover, species richness, vegetation composition, frequency, and density. The ecological analysis included principal component analysis to compare the distributions of sustained and lost vegetation in response to water flow variables. This research showed that several plant species withstand periods of high peak flow, like Salix tetrasperma, Rumex dentatis, Trifolium resupinatum, and Polygonum. Additionally, visual observations, plot surveys, transects, and published reports were used to compile the faunal data used to determine habitat distribution. According to the analysis, immediate effects of dam construction activities such as blasting, quarrying, and traffic noise cause severe disturbances to existing biodiversity and habitats with high ecological vulnerability, and have long‐term effects on ecological integrity and environmental health in downstream and upstream habitats. The study presents the present status of biological and ecological conditions, as a baseline reference datum for a comparative analysis of the changes caused by the dam's construction.

Stochastic Volatility Modeling of Daily Streamflow Time Series

AbstractUnder the changing climate, the natural characteristics of hydrological processes are assumed to have been intensified, and the volatility of these processes to have increased significantly. However, the applicability of traditional time series analysis methods and the commonly used Gaussian GARCH (Generalized AutoRegressive Conditional Heteroskedasticity) to streamflow modeling has been limited. Although SV‐type (stochastic volatility) models have appeared as competitive alternatives to GARCH‐type models owing to their flexibility in modeling volatilities, they have not been applied in hydrological studies. Therefore, this study assesses the applicability of SV models to streamflow modeling using daily streamflow series from 21 hydrological stations in the Yellow River basin. Considering the influence of different types of GARCH and residual distributions, 7 hybrid models with variance fluctuation (fractional autoregressive integrated moving average‐GARCH) based on 9 distributions are compared to determine the optimal model for each station. Then 4 SV‐type models are introduced and compared with the results of the optimal GARCH‐type model to verify their applicability. The results show that: (a) the Gaussian distribution is not applicable in both GARCH‐type and SV‐type models for modeling daily streamflow; (b) although the GARCH‐type models are shown to describe the volatility of streamflow processes and improve the modeling performance, large residuals have been observed in the results of the analysis during the peak flow period; and (c) SV‐type models can better describe the streamflow series with time‐varying variance and accurately capture the occurrence of peak streamflow. The findings of this study offer practical and promising time series analysis methods for daily streamflow modeling.

A traffic status evaluation method of expressway merging area based on improved coupling theory

In order to further reveal the law and characteristics of on-ramp traffic flow into the main line of expressway road and make up for the deficiency of traditional inflow model which cannot evaluate the state of merging area, the coupling theory in physics was introduced. First of all, “gap acceptance” model was adopted to describe the operation law of merging area, and the relationship between important parameters such as flow rate and headway was analyzed by using discrete probability function. Second, coupling degree and coupling coordination degree were put forward, after analyzing the characteristic under the premise of the merging area, using a large amount of measured data regression analysis of the traffic, location speed and the headway of parameters in the coupling. The coupling theory was modified, the coupling function evaluation model of confluence area was established, and the interaction and influence between main line and ramp system were quantitatively analyzed and evaluated. Finally, the model is verified by the actual observation data of Shanghai expressway. The results indicate that in the early peak period, the coupling coordination degree is about 0.36 and 0.4, which is in a moderate coordination stage. During the peak flow period, the coupling coordination degree is only 0.28, which is in a low degree of coordination coupling and the system is relatively disordered. In nonpeak hours, the coupling coordination degree is around 0.83, which is in an extremely coordinated state. The error between the flow calculated by the coupling theory and the data observed in the field is generally 4.2%–12.8%, which indicates that the results of the running status evaluation of merging area by using this model are reliable.

Flood Risk Assessment under Climate Change: The Petite Nation River Watershed

In Canada, climate change is expected to increase the extreme precipitation events by magnitude and frequency, leading to more intense and frequent river flooding. In this study, we attempt to map the flood hazard and damage under projected climate scenarios (2050 and 2080). The study was performed in the two most populated municipalities of the Petite Nation River Watershed, located in southern Quebec (Canada). The methodology follows a modelling approach, in which climate projections are derived from the Hydroclimatic Atlas of Southern Quebec following two representative concentration pathways (RCPs) scenarios, i.e., RCP 4.5 and RCP 8.5. These projections are used to predict future river flows. A frequency analysis was carried out with historical data of the peak flow (period 1969–2018) to derive different return periods (2, 20, and 100 years), which were then fed into the GARI tool (Gestion et Analyse du Risque d’Inondation). This tool is used to simulate flood hazard maps and to quantify future flood risk changes. Projected flood hazard (extent and depth) and damage maps were produced for the two municipalities under current and for future scenarios. The results indicate that the flood frequencies are expected to show a minor decrease in peak flows in the basin at the time horizons, 2050 and 2080. In addition, the depth and inundation areas will not significantly change for two time horizons, but instead show a minor decrease. Similarly, the projected flood damage changes in monetary losses are projected to decrease in the future. The results of this study allow one to identify present and future flood hazards and vulnerabilities, and should help decision-makers and the public to better understand the significance of climate change on flood risk in the Petite Nation River watershed.

Effects of flow-controlled vacuum on milking performance and teat condition in a rotary milking parlor

The objective of this study was to compare a vacuum control system that increases milking system vacuum during the peak flow period of milking to conventional constant vacuum control technology regarding its effect on milk flowrate and milking duration. Further objectives were to study the effects of flow-controlled vacuum on milking parlor performance. An observational study was conducted on a commercial dairy farm milking from 848 to 896 cows per day over the study period using a 60-stall rotary milking parlor. The flow-controlled vacuum control system was applied for 3 wk. Milking performance and teat condition were compared with 3-wk periods prior and subsequent to the test period using conventional vacuum control. Statistical analysis was performed assuming a cross-sectional study design during each period. Flow-controlled vacuum increased peak milk flowrate by 12% and increased average milk flowrate by 4%. The decrease in individual cow milking duration was proportional to milk yield per milking. Postmilking teat condition was good during the entire study period. The occurrence of rough teat ends was slightly reduced during the flow-controlled vacuum period with no meaningful difference in the occurrence of teats with blue color, palpable rings, or petechia. The combination of reduced vacuum during the low flow period of milking and the decrease in milking duration are likely factors that are protective of teat tissues. Bioeconomic modeling of the use of flow-controlled vacuum on the performance of rotary milking parlors, using the data that were collected during the study, showed that the reduction in milking duration of individual cows allows a higher rotary parlor speed. Modeled parlor throughput increased by 5.0% to 419 cows/h, 6.8% to 407 cows/h, and 4.2% to 326 cows/h when 80%, 95%, and 99% of the cows were finished milking at the end of the rotation for a 60-stall parlor. Model results showed that increased parlor throughput resulted in increased labor efficiency, reduced labor costs for milking, and a positive benefit-cost ratio on the investment for all but the smallest herd and parlor sizes considered.

Analysis of Flow Characteristics and Step Size of Escalators at Metro Stations

This paper discusses the analysis of flow characteristics on escalators and examines the adequacy of step size. The study was carried out on nine escalators at three metro stations in New Delhi, the capital city of India. Data were collected during morning and evening peak flow periods. Peak flows on the escalators being studied are observed to be higher during evening period as compared to the morning period. Flow values are quite high when compared with flow values at metro stations in China or England or on similar facilities at railway stations. Maximum density was found higher as compared to that reported in China and England and comparable to that at railway stations in India. Space per person was found comparable to the reported values. Relationships between flow characteristics were also developed. Step dimension adequacy was checked and suggested to be modified in the light of person body dimension reported in different guidelines. The outcome will assist the planners to take considered decisions related to escalators.

The impact of initial conditions on convection-permitting simulations of a flood event over complex mountainous terrain

Abstract. Western Norway suffered major flooding after 4 d of intense rainfall during the last week of October 2014. While events like this are expected to become more frequent and severe under a warming climate, convection-permitting scale models are showing their skill with respect to capturing their dynamics. Nevertheless, several sources of uncertainty need to be taken into account, including the impact of initial conditions on the precipitation pattern and discharge, especially over complex, mountainous terrain. In this paper, the Weather Research and Forecasting Model Hydrological modelling system (WRF-Hydro) is applied at a convection-permitting scale, and its performance is assessed in western Norway for the aforementioned flood event. The model is calibrated and evaluated using observations and benchmarks obtained from the Hydrologiska Byråns Vattenbalansavdelning (HBV) model. The calibrated WRF-Hydro model performs better than the simpler conceptual HBV model, especially in areas with complex terrain and poor observational coverage. The sensitivity of the precipitation pattern and discharge to poorly constrained elements such as spin-up time and snow conditions is then examined. The results show the following: (1) the convection-permitting WRF-Hydro simulation generally captures the precipitation pattern/amount, the peak flow volume and the timing of the flood event; (2) precipitation is not overly sensitive to spin-up time, whereas discharge is slightly more sensitive due to the influence of soil moisture, especially during the pre-peak phase; and (3) the idealized snow depth experiments show that a maximum of 0.5 m of snow is converted to runoff irrespective of the initial snow depth and that this snowmelt contributes to discharge mostly during the rainy and the peak flow periods. Although further targeted experiments are needed, this study suggests that snow cover intensifies the extreme discharge instead of acting as a sponge, which implies that future rain-on-snow events may contribute to a higher flood risk.

Short communication: Effects of changing teatcup removal and vacuum settings on milking efficiency of an automatic milking system

The aim of this experiment was to assess strategies to reduce milking time in a pasture-based automatic milking system (AMS). Milking time is an important factor in automatic milking because any reductions in box time can facilitate more milkings per day and hence higher production levels per AMS. This study evaluated 2 end-of-milking criteria treatments (teatcup removal at 30% and 50% of average milk flowrate at the quarter-level), 2 milking system vacuum treatments (static and dynamic, where the milking system vacuum could change during the peak milk flowrate period), and the interaction of these treatment effects on milking time in a Lely Astronaut A4 AMS (Maassluis, the Netherlands). The experiment was carried out at the research facility at Teagasc Moorepark, Cork, Ireland, and used 77 spring-calved cows, which were managed on a grass-based system. Cows were 179 DIM, with an average parity of 3. No significant differences in milk flowrate, milk yield, box time, milking time, or milking interval were found between treatments in this study on cows milked in an AMS on a pasture-based system. Average and peak milk flowrates of 2.15 kg/min and 3.48 kg/min, respectively, were observed during the experiment. Small increases in maximum milk flowrate were detected (+0.09 kg/min) due to the effect of increasing the system vacuum during the peak milk flow period. These small increases in maximum milk flowrate were not sufficient to deliver a significant reduction in milking time or box time. Furthermore, increasing the removal setting from 30% of the average milk flowrate to 50% of the average milk flowrate was not an effective means of reducing box time, because the resultant increase in removal flowrate of 0.12 kg/min was not enough to deliver practical or statistically significant decreases in milking time or box time. Hence, to make significant reductions in milking time, where cows have an average milk flow of 2 kg/min and yield per milking of 10 kg, end-of-milking criteria above 50% of average milk flowrate at the quarter level would be required.

Evaluation of Meltwater Quality Using Dissolved Ions Chemistry and Multivariate Statistical Methods: A Case Study of the Manimahesh Glacier, Ravi Basin, Himachal Pradesh, India

The hydrogeochemical study on glacial meltwater gives important information about the quality of meltwater and weathering processes controlling dissolved ions chemistry in the glacierized area. Anionic abundance in the Manimahesh Glacier meltwater shows a trend of HCO3− > SO42− > Cl− = NO3−, whereas cationic abundance in the meltwater shows a trend of Ca2+ > Mg2+ > K+ > Na+. On the basis of high equivalent ratios of (Ca + Mg) versus (Na + K) and (Ca + Mg) versus TZ+ (total cations) and low equivalent ratio of (Na + K) versus TZ+, carbonate-type weathering has been identified as a major hydrogeochemical process regulating solute chemistry of the Manimahesh Glacier meltwater followed by silicate weathering. About 80% of bicarbonate in the meltwater of investigation area was mainly generated from carbonate weathering, whereas 20% of bicarbonate was produced from silicate weathering. The result of statistical methods (correlation, principal component and cluster analysis) shows that meltwater quality of the Manimahesh Glacier is mainly governed by carbonate and silicate-type weathering, oxidation of pyrite, dissolution of sulphate minerals and atmospheric input. The average value of suspended sediment concentration (SSC) in the glacier meltwater was calculated to be 46 mg/l and 63 mg/l during the month of June and July 2014, respectively, showing higher concentration of SSC during the month of July (peak-flow period) followed by June (low-flow period).

English

Water quality concerns have been very crucial because good quality water supplies in abundance and readily available for production and productivity is of great importance. Therefore, the study was conducted to assess irrigation water quality of the lowlands of Delo Menna and Berbere districts. The samples were collected from the upstream and downstream of the canals along the farms of the districts during the medium and low peaks of the rivers’ flow. About 1 L of water sample was collected from each site. Likewise, the sampling date was on the 15th of designated months. Accordingly, the results reveal that the surface irrigation water has less salinity, sodium hazard and residual sodium carbonate hazard in the irrigated canals and canals along the farms. The electrical conductivity ranges from 0.17 to 0.49 ds/m at lower peak and from 0.06 to 0.24 ds/m at medium peak in Delo Menna district. Moreover, the residual sodium carbonate ranges from 1.34 to 2.57 at lower peak flow and 0.79 to 1.30 at medium peak flows; sodium concentration ranges from 0.36 to 0.46 meq/L at lower peak of the river flow and very small concentrations at the medium peak flow period in Berbere district. The salinity indicator parameters such as all cations and anions, total dissolved solid, adjusted sodium ratio, residual sodium carbonates in the irrigated rivers were low in Delo Menna and Berbere. Therefore, the rivers in both districts are normal for agricultural production of all types of crops which are grown in the low lands of Bale. Key words: Cation, anion, assessment, conductivity, irrigation, water quality.

Demonstration of innovative MABR low-energy nutrient removal technology at Chicago MWRD

Abstract An innovative MABR (membrane-aerated biofilm reactor) membrane technology was demonstrated at the O'Brien Water Reclamation Plant (OWRP) of the Metropolitan Water Reclamation District of Greater Chicago (Chicago MWRD). The demonstration unit was equipped with one full-scale membrane cassette. The technology was evaluated for its potential to improve performance for total suspended solids (TSS) and ammonia removal during stressed conditions (specifically cold temperature peak flow periods) and to meet future effluent phosphorous limits. Over a period of 9 months, the MABR oxygen transfer rate was stable and ranged between 8 and 12 g-O2/d/m2 of membrane surface area. The nitrification rate varied between 0.5 and 2.5 g-N/d/m2 and was affected primarily by the ammonia loading rate and the feed carbon to nitrogen ratio. Most of the oxygen transferred was accounted for by nitrification. The MABR hybrid process enables important process improvements while reducing plant energy consumption.

A method for assessing teatcup liner performance during the peak milk flow period

The objective of this study was to develop a method to quantify the milking conditions under which circulatory impairment of teat tissues occurs during the peak flow period of milking. A secondary objective was to quantify the effect of the same milking conditions on milk flow rate during the peak flow rate period of milking. Additionally, the observed milk flow rate was a necessary input to the calculation of canal area, our quantitative measure of circulatory impairment. A central composite experimental design was used with 5 levels of each of 2 explanatory variables (system vacuum and pulsator ratio), creating 9 treatments including the center point. Ten liners, representing a wide range of liner compression (as indicated by overpressure), were assessed, with treatments applied using a novel quarter-milking device. Eight cows (32 cow-quarters) were used across 10 separate evening milkings, with quarter being the experimental unit. The 9 treatments, with the exception of a repeated center point, were randomly applied to all quarters within each individual milking. Analysis was confined to the peak milk flow period. Milk flow rate (MFR) and teat canal cross sectional area (CA) were normalized by dividing individual MFR, or CA, values by their within-quarter average value across all treatments. A multiple explanatory variable regression model was developed for normalized MFR and normalized CA. The methods presented in this paper provided sufficient precision to estimate the effects of vacuum (both at teat-end and in the liner mouthpiece), pulsation, and liner compression on CA, as an indicator of teat-end congestion, during the peak flow period of milking. Liner compression (as indicated by overpressure), teat-end vacuum, vacuum in the liner mouthpiece, milk-phase time, and their interactions are all important predictors of MFR and teat-end congestion during the peak milk flow period of milking. Increasing teat-end vacuum and milk-phase time increases MFR and reduces CA (indicative of increased teat-end congestion). Increasing vacuum in the liner mouthpiece also acts to reduce CA and MFR. Increasing liner compression reduces the effects of teat-end congestion, resulting in increased MFR and increased CA at high levels of teat-end vacuum and milk-phase time. These results provide a better understanding of the balance between milking speed and milking gentleness.

Recently growing subaqueous flowstones: Occurrence, petrography, and growth conditions

Abstract Subaqueous flowstones have been studied in two resurgence caves in Slovak Karst (southern Slovakia), namely Krasnohorska and Drienovska Caves. The flowstones litter streambeds within the distance of several hundred meters upstream from resurgences. They form laminated crusts within channels of the underground streams flowing through the caves. Layers composed of columnar sparry calcite alternate with those composed of microcrystalline calcite. The latter are enriched in fine, detrital, non-carbonate components, which resulted in crystallization of microcrystalline calcite instead of sparry calcite. The growth rate of the studied flowstones reaches 0.96 mg/cm 2 /day, which corresponds to ca. 0.3 mm per year. Seasonal observations conducted between November 2010 and September 2012 reveal that deposition of subaqueous flowstones in the studied caves significantly depends on the local hydrological conditions. During the periods of low flow, SI calc. values of underground stream increase and columnar sparry calcite grows. Conversely, during peak flow periods SI calc. values decrease and subaqueous flowstones are subjected to destruction, both by mechanical erosion and corrosion. The decreasing discharge, just after peak flows, causes deposition of fine-grained particles, which results in precipitation of microcrystalline layers. Subaqueous flowstones grow in complete darkness and in atmosphere with elevated CO 2 content, similarly to typical speleothems, but they are fed with turbulent stream water, similarly to calcareous tufas. Their growth rate is higher than those of ‘normal’ flowstones fed with a film of water seeping down; it falls within a range of growth rate of calcareous tufas, though near the lower limit of this range. Therefore, subaqueous flowstones represent an intermediate link between other speleothems and tufas deposited outside the cave environment.

Using High Spatio-Temporal Optical Remote Sensing to Monitor Dissolved Organic Carbon in the Arctic River Yenisei

In Arctic regions, a major concern is the release of carbon from melting permafrost that could greatly exceed current human carbon emissions. Arctic rivers drain these organic-rich watersheds (Ob, Lena, Yenisei, Mackenzie, Yukon) but field measurements at the outlets of these great Arctic rivers are constrained by limited accessibility of sampling sites. In particular, the highest dissolved organic carbon (DOC) fluxes are observed throughout the ice breakup period that occurs over a short two to three-week period in late May or early June during the snowmelt-generated peak flow. The colored fraction of dissolved organic carbon (DOC) which absorbs UV and visible light is designed as chromophoric dissolved organic matter (CDOM). It is highly correlated to DOC in large arctic rivers and streams, allowing for remote sensing to monitor DOC concentrations from satellite imagery. High temporal and spatial resolutions remote sensing tools are highly relevant for the study of DOC fluxes in a large Arctic river. The high temporal resolution allows for correctly assessing this highly dynamic process, especially the spring freshet event (a few weeks in May). The high spatial resolution allows for assessing the spatial variability within the stream and quantifying DOC transfer during the ice break period when the access to the river is almost impossible. In this study, we develop a CDOM retrieval algorithm at a high spatial and a high temporal resolution in the Yenisei River. We used extensive DOC and DOM spectral absorbance datasets from 2014 and 2015. Twelve SPOT5 (Take5) and Landsat 8 (OLI) images from 2014 and 2015 were examined for this investigation. Relationships between CDOM and spectral variables were explored using linear models (LM). Results demonstrated the capacity of a CDOM algorithm retrieval to monitor DOC fluxes in the Yenisei River during a whole open water season with a special focus on the peak flow period. Overall, future Sentinel2/Landsat8 synergies are promising to monitor DOC fluxes in Arctic rivers and advance our understanding of the Earth’s carbon cycle.

Spatio-temporal assimilation of modelled catchment loads with monitoring data in the Great Barrier Reef

Soil erosion and sediment transport into waterways and the ocean can adversely affect water clarity, leading to the deterioration of marine ecosystems such as the iconic Great Barrier Reef (GBR) in Australia. Quantifying a sediment load and its associated uncertainty is an important task in delineating how changes in management practices can contribute to improvements in water quality, and therefore continued sustainability of the GBR. However, monitoring data are spatially (and often temporally) sparse, making load estimation complicated, particularly when there are lengthy periods between sampling or during peak flow periods of major events when samples cannot be safely taken. We develop a spatio-temporal statistical model that is mechanistically motivated by a process-based deterministic model called Dynamic SedNet. The model is developed within a Bayesian hierarchical modelling framework that uses dimension reduction to accommodate seasonal and spatial patterns to assimilate monitored sediment concentration and flow data with output from Dynamic SedNet. The approach is applied in the Upper Burdekin catchment in Queensland, Australia, where we obtain daily estimates of sediment concentrations, stream discharge volumes and sediment loads at 411 spatial locations across 20 years. Our approach provides a method for assimilating both monitoring data and modelled output, providing a statistically rigorous method for quantifying uncertainty through space and time that was previously unavailable through process-based models.

How does climate change affect combined sewer overflow in a system benefiting from rainwater harvesting systems?

Combined Sewer Overflow (CSO) infrastructure are conventionally designed based on historical climate data. Yet, variability in rainfall intensities and patterns caused by climate change have a significant impact on the performance of an urban drainage system. Although rainwater harvesting (RWH) is a potential solution to manage stormwater in urban areas, its benefits in mitigating the climate change impacts on combined sewer networks have not been assessed yet. Hence, the goal of the present study was set to evaluate the effectiveness of RWH in alleviating the potential impacts of climate change on CSOs. To do so, first, future rainfall was achieved through the Coupled Model Intercomparison Project Phase 5 (CMIP5) based on modified historical record. Then, rainfall-runoff modeling was employed using the U.S. EPA Stormwater management model (SWMM) to study the response of CSO outfalls to future rainfall. The study site was the combined sewer network of the City of Toledo, Ohio. Results showed that under the maximum impact scenario in the near future, climate change might cause up to approximately 12–18% increase in CSOs occurrence, volume and duration in Toledo. However, an RWH plan with the capacity of 0.76m3 (200gal) implemented on half on the buildings throughout the area, appeared to be able to mitigate the potential future impacts, and showed a remarkable controlling performance in the peak flow periods. This plan also met toilet flushing demands. Therefore, RWH can be considered as a feasible solution to mitigate future climate change impacts on CSOs and supply water demands.

A quarter milking analysis device – Development and demonstration

The objective of this paper was to describe and demonstrate a novel quarter milking analysis device (Mi4) for use in the field of bovine milking research. The Mi4 was developed for investigating the effects of milking machine factors such as vacuum level, pulsation settings and liner characteristics on milk flow rate (MFR) during the peak flow period from individual teats within a single milking. A method to use MFR, teat-end vacuum and pulsation characteristics measured with this device was developed to estimate teat-end tissue congestion. The changes in teat-end thickness, and changes in teat canal cross sectional area, induced by congestion are small, hence a high precision device is required to detect the resulting subtle changes in MFR. No device has been described in the literature that can apply multiple experimental milking treatments within a single milking while simultaneously recording quarter level response data. This within-milking approach accounts for non-linearity as total milk mass increases and is independent of any effect of milk hose slope and positioning. Sources of variability exist in MFR within an individual quarter, from quarter to quarter, between cows and from day to day. Understanding and controlling for these natural sources of variation is critical for the successful deployment of the Mi4 in milking experiments. Experimental results demonstrate that the Mi4 equipment and methods can detect changes in quarter MFR as small as 2% by applying treatments within the peak flow period of individual quarters, thus making it a useful tool for milking machine research.

Stable oxygen isotope variability in two contrasting glacier river catchments in Greenland

Abstract. Analysis of stable oxygen isotope (δ18O) characteristics is a useful tool to investigate water provenance in glacier river systems. In order to attain knowledge on the diversity of δ18O variations in Greenlandic rivers, we examined two contrasting glacierised catchments disconnected from the Greenland Ice Sheet (GrIS). At the Mittivakkat Gletscher river, a small river draining a local temperate glacier in southeast Greenland, diurnal oscillations in δ18O occurred with a 3 h time lag to the diurnal oscillations in run-off. The mean annual δ18O was −14.68 ± 0.18 ‰ during the peak flow period. A hydrograph separation analysis revealed that the ice melt component constituted 82 ± 5 % of the total run-off and dominated the observed variations during peak flow in August 2004. The snowmelt component peaked between 10:00 and 13:00 local time, reflecting the long travel time and an inefficient distributed subglacial drainage network in the upper part of the glacier. At the Kuannersuit Glacier river on the island Qeqertarsuaq in west Greenland, the δ18O characteristics were examined after the major 1995–1998 glacier surge event. The mean annual δ18O was −19.47 ± 0.55 ‰. Despite large spatial variations in the δ18O values of glacier ice on the newly formed glacier tongue, there were no diurnal oscillations in the bulk meltwater emanating from the glacier in the post-surge years. This is likely a consequence of a tortuous subglacial drainage system consisting of linked cavities, which formed during the surge event. Overall, a comparison of the δ18O compositions from glacial river water in Greenland shows distinct differences between water draining local glaciers and ice caps (between −23.0 and −13.7 ‰) and the GrIS (between −29.9 and −23.2 ‰). This study demonstrates that water isotope analyses can be used to obtain important information on water sources and the subglacial drainage system structure that is highly desired for understanding glacier hydrology.

Methods of estimating liner compression

The aim of this study was to compare 2 methods of measuring overpressure (OP) using a new test device designed to make OP measurements more quickly and accurately. Overpressure was measured with no pulsation (OPnp) and with limited pulsation (OPlp) repeatedly on the same cow during a single milking. Each of the 6 liners (3 round liners and 3 triangular liners) used in this study were tested on the same 6 experimental cows. Both OPnp and OPlp were measured on all 4 teats of each experimental cow twice for each liner. The order of OPnp and OPlp alternated sequentially for each cow test. The OP results for the 6 liners were also compared with liner compression estimated on the same liners with a novel artificial teat sensor (ATS). The OPlp method showed small but significantly higher values than the OPnp method (13.9 vs. 13.4kPa). The OPlp method is recommended as the preferred method as it more closely approximates normal milking condition. Overpressure values decreased significantly between the first and the following measurements, (from 15.0 to 12.4kPa). We recommend performing the OP test at a consistent time, 1min after attaching the teatcup to a well-stimulated teat, to reduce the variability produced by OP changing during the peak flow period. The new test device had several advantages over previously published methods of measuring OP. A high correlation between OP and liner compression estimated by the ATS was found, but difficulties were noted when using the ATS with triangular liners.