Characterising Rhythmic and Episodic Pulsing Behaviour in the Castleton Karst, Derbyshire (UK), Using High Resolution in-Cave Monitoring

The discharge from most karst springs exhibits a consistent and reasonably predictable response to recharge but a few exhibit short-term (‘rhythmic’) changes in flow that are commonly attributed to the geometry of feeder conduits and the action of siphons. This paper investigates water flow in a karst system that exhibits rhythmic and episodic changes in discharge due to variations in flow from two phreatic conduits (Main Rising (MR) and Whirlpool Rising (WR)) that pass through Speedwell Cavern en route to the springs. Water tracing experiments indicate that the conduits receive both allogenic and autogenic recharge. Flow dynamics and conduit behaviour were investigated using high-resolution (2-min) water depth data collected from MR and WR between 2012 and 2015 (when MR was dominant) and between 2021 and 2023 (when WR was dominant). Water depths were also logged in a cave at the upstream end of a conduit draining to both MR and WR and at springs. The short-term temporal variability in water depths at both MR and WR is greater than any documented in previous studies. This is attributed to conduit bedrock geometry and changes in conduit permeability due to sediment accumulation in phreatic loops, which together influence the response to recharge

From recharge to cave to spring:transmission of a flood pulse through a complex karst conduit network, Castleton, Derbyshire (UK)

Storm Babet (18–21 October 2023) brought heavy and persistent rain (80–100 mm) to the English Peak District, causing widespread surface and underground flooding. The village of Castleton experienced groundwater flooding from springs that drain a complex mixed allogenic–autogenic karst catchment. Transmission of the flood pulse was monitored using high-resolution (2 and 4 min intervals) logging of (a) the hydraulic head at five underground locations in the karst conduits and (b) the water depth at three springs and in the surface river fed by the springs. Underground, there were large increases in the hydraulic head (9–35 m), which resulted in two types of flow switching. Firstly, the increased head at the input end of a phreatic (water-filled) conduit system removed an underwater permeability barrier in a relatively low-elevation conduit, resulting in a dramatic increase in flow out of the conduit and a corresponding decrease in flow from a linked higher-elevation conduit that had dominated before the storm. Secondly, the increased head upstream of two conduits with limited hydraulic conductivity allowed water to spill over into conduits that were inactive prior to the storm. As expected, the conduits fed by sinking streams from the allogenic catchment responded rapidly to the recharge, but there was also a rapid response from the autogenic catchment where there are no surface streams and only a small number of dolines. The complex signals measured underground are not apparent from the spring hydrographs

The History, Status and Management of Muskoxen on Banks Island

Historical and archaeological records suggest that muskoxen (Ovibos moschatus) were once abundant on Banks Island. They declined around the turn of the 20th century and remained at very low population levels until the 1970s. The causes of the scarcity of muskoxen are unknown, but severe freezing rains and subsequent forage unavailability likely played a role. Aerial surveys documented an increase in the estimated population size from 3800 in 1972 to 34,225 in 1989. The rapid increase in muskox numbers has been a source of concern to the local users, who view the muskoxen as detrimental to the caribou (Rangifer tarandus pearyi), which have declined in number. Since the mid-1980s, productivity of 3-year-old muskox cows and calf survival have decreased and the prevalence of parasites has increased. Our data do not allow us to distinguish between whether those changes are density-dependent population responses or the effects of the severity of winter weather. Current management focuses on monitoring the trend of population size, the condition and reproduction of the muskoxen.Key words: muskoxen, Ovibos moschatus, Banks Island, numbers, harvest, weather, population regulationMots clés: boeuf musqué, Ovibos moschatus, île de Banks, nombres, récolte, temps, contrôe de la populatio

Segmented waveguides in thin silicon-on-insulator

We have developed new silicon-on-insulator waveguide designs for simultaneously achieving both low-loss optical confinement and electrical contacts, and we present a design methodology based on calculating the Bloch modes of such segmented waveguides. With this formalism, waveguides are designed in a single thin layer of silicon-on-insulator to achieve both optical confinement and minimal insertion loss. Waveguides were also fabricated and tested, and the measured data were found to closely agree with theoretical predictions, demonstrating input insertion loss and propagation loss better than 0.1 dB and -16 dB/cm, respectively

Spatio-temporal influence of tundra snow properties on Ku-band (17.2 GHz) backscatter

During the 2010/11 boreal winter, a distributed set of backscatter measurements was collected using a ground-based Ku-band (17.2 GHz) scatterometer system at 26 open tundra sites. A standard snow-sampling procedure was completed after each scan to evaluate local variability in snow layering, depth, density and water equivalent (SWE) within the scatterometer field of view. The shallow depths and large basal depth hoar encountered presented an opportunity to evaluate backscatter under a set of previously untested conditions. Strong Ku-band response was found with increasing snow depth and snow water equivalent (SWE). In particular, co-polarized vertical backscatter increased by 0.82 dB for every 1 cm increase in SWE (R2 = 0.62). While the result indicated strong potential for Ku-band retrieval of shallow snow properties, it did not characterize the influence of sub-scan variability. An enhanced snow-sampling procedure was introduced to generate detailed characterizations of stratigraphy within the scatterometer field of view using near-infrared photography along the length of a 5m trench. Changes in snow properties along the trench were used to discuss variations in the collocated backscatter response. A pair of contrasting observation sites was used to highlight uncertainties in backscatter response related to short length scale spatial variability in the observed tundra environment

Values-based food chains – Recoupling man and soil?

Abstract – A market driven sustainable develop-ment of organic agriculture depends on the abilities of the organic food chains to mediate qualities (vales) form place of production to place of consumption. A Pirsig’s based relational analysis reveals the importance of the abilities of all actors of the food chain to relate to and to include these qualities in their strategy. Transparency along the whole chain all way back to place and mode of production seem important

Integration of the FGS ETU to the ISIM Structure

No abstract availabl

Considerations for managing beef cows in confinement

Continued volatility of grain markets, coupled with recent summer droughts, has had a significant impact on the Midwestern cow-calf sector in recent years. These factors, along with decreased land availability for grazing and forage production, has resulted in increased cost of production and left many producers pondering alternative management systems for their herds. One such management alternative that is capturing the interest of many producers is the concept of confinement housing of the cow herd. In many parts of the United States, where year-round grazing is either not feasible, or is not implemented, confinement housing of the cow herd is not necessarily a novel practice. Often times, cows are placed on a sacrifice paddock or drylot with varying degrees of access to shelter for a period of time during the winter months, leading up to and sometimes through the calving season. However, with reduced land access and increasing forage prices, an increased proportion of producers are managing cows in confinement during times of the year traditionally devoted to grazing. With these management alterations come various considerations that should be acknowledged