A dated cave sediment record of Pleistocene transgressions on Berry Head,Southwest England

Berry Head, a limestone headland in Torbay, southwest England, exhibits a series of subaerial marine erosion platforms and raised beaches spanning an altitude range of 97 m. Solution caves on the headland show preferred horizontal development at elevations that are correlated with the marine erosion platforms, and developed in a marine/freshwater mixing zone whose position was controlled by high sea-level still-stands. Corbridge Cave in Berry Head Quarry lies below the raised beaches in Torbay, and contains evidence of three marine transgressions in the form of fine-grained marine ponding deposits with a marine microfauna. Uranium-series dating of intercalated speleothems indicates that a transgression during oxygen isotope stage 5e reached an elevation of 5.8 m OD, while an earlier transgression (probably during stage 7) reached at least 7.2 m OD. These findings are used to constrain possible interpretations of the aminostratigraphy of raised beaches in Southwest Britain, and a correlation of the Unnamed Stage of Bowen, Sykes, Reeves, Miller, Andrews, Brew and Hare with oxygen isotope stage 5e is proposed.     

Agents of Eviction: The Squatter Control and Clearance Division of Hong Kong's Housing Department

More is known about the policies that produce forced evictions and their consequences than about the agencies whose responsibility it is to conduct them. Understanding the nature of forced evictions requires greater comprehension of responsible agencies since the ways in which they implement policies may be a crucial intervening variable influencing the outcomes. In this paper, I use documentary and ethnographic research to describe the Squatter Control and Clearance Division of the Hong Kong Housing Department. Responsible both for evicting squatters and for controlling squatter areas that are permitted to remain for the time being, officers must respond to the conflicts and challenges of their twin, partially conflicting, mandates. Examination of changes in squatter control and clearance practices since 1954 is followed by a brief case study of the most recent squatter clearance that occurred in July 2001.     

Water and sediment outbursts from advanced Franz Josef Glacier,New Zealand

The Franz Josef Glacier, Westland, New Zealand, has a history of catastrophic sediment‐laden outburst ?oods associated with extreme rainfall events when the glacier toe is advanced over its own sediments. Consideration of these events and inspection of recent sediment deposits suggest that there are three distinct modes of outburst. The ?rst is associated with fans fed by over?ow along the glacier margin. As the glacier has advanced across its own fore?eld gravels, it is inferred that the primary drainage conduit has developed a reach of negative slope. In high ?ows massive boulders can block the conduit, trapping lesser clasts. The resulting backup of water causes over?ows through marginal moulins, producing the fan type of deposit. The second type of outburst deposits massive imbricated boulders at a greater or lesser distance from the glacier portal. In this case, pressure buildup drives the blockage out of the portal where the boulders deposit. Smaller materials are generally carried away. The third type consists of very shallow ?ows, and produces massive gravel deposits of uncertain provenance. In this condition, the excess pressure in the conduit results in slight uplift of the glacier and widespread discharge of water and sediment below the glacier snout; gravels and smaller sediments are laid down in a massive deposit across the fore?eld. The massive, boulder‐veneered deposit from the December 1995 outburst is interpreted in the light of the above mechanisms as a hyperconcentrated ?ow deposit from hydraulic jacking, overlain by boulders emplaced by a subsequent conduit outburst. A possible association of outbursts with the present advanced position of the glacier is suggested. Copyright © 2003 John Wiley & Sons, Ltd.     

The dynamics of natural pipe hydrological behaviour in blanket peat

Natural soil pipes are found in peatlands, but little is known about their hydrological role. This paper presents the most complete set of pipe discharge data to date from a deep blanket peatland in Northern England. In a 17.4‐ha catchment, we identified 24 perennially flowing and 60 ephemerally flowing pipe outlets. Eight pipe outlets along with the catchment outlet were continuously gauged over an 18‐month period. The pipes in the catchment were estimated to produce around 13.7% of annual streamflow, with individual pipes often producing large peak flows (maximum peak of 3.8 l s^?1). Almost all pipes, whether ephemerally or perennially flowing, shallow or deep (outlets > 1 m below the peat surface), showed increased discharge within a mean of 3 h after rainfall commencement and were dominated by stormflow, indicating good connectivity between the peatland surface and the pipes. However, almost all pipes had a longer period between the hydrograph peak and the return to base flow compared with the stream (mean of 23.9 h for pipes, 19.7 h for stream). As a result, the proportion of streamflow produced by the pipes at any given time increased at low flows and formed the most important component of stream discharge for the lowest 10% of flows. Thus, a small number of perennially flowing pipes became more important to the stream system under low‐flow conditions and probably received water via matrix flow during periods between storms. Given the importance of pipes to streamflow in blanket peatlands, further research is required into their wider role in influencing stream water chemistry, water temperature and fluvial carbon fluxes, as well as their role in altering local hydrochemical cycling within the peat mass itself. Enhanced piping within peatlands caused by environmental change may lead to changes in the streamflow regime with larger low flows and more prolonged drainage of the peat. Copyright © 2012 John Wiley & Sons, Ltd.     

Fisheries mismanagement

We analysed the extent to which European politicians have adhered to scientific recommendations on annual total allowable catches (TACs) from 1987 to 2011, covering most of the period of the Common Fisheries Policy (CFP). For the 11 stocks examined, TACs were set higher than scientific recommendations in 68% of decisions. Politically-adjusted TACs averaged 33% above scientifically recommended levels. There was no evidence that the 2002 reform of the CFP improved decision-making, as was claimed at the time. We modelled the effects of such politically-driven decision-making on stock sustainability. Our results suggest that political adjustment of scientific recommendations dramatically increases the probability of a stock collapsing within 40 years.In 2012 European fisheries policy will undergo a once-a-decade reform. Ten years ago radical reforms were promised but the changes failed to improve sustainability. It is likely that the 2012 reform will be similarly ineffective unless decision-making is changed so that catch allocations are based on science rather than politics.     

DO WE NEED TO MODEL PLATES AT ALL?

The historical method of obtaining equatorial coordinates for stars observed via astronomical photography has been to convert the measured coordinates to equatorial coordinates with the aid of a plate model which corrects for a variety of effects. However, we now have at our disposal novel smoothing techniques, of considerable generality, which in conjunction with modern star catalogues can reproduce the essence of the plate model while dramatically minimizing both the fortuitous and systematic errors of observation. In this paper we demonstrate that, with this technique and extant catalogues, one can obtain, with at least the same precision and better accuracy, the information necessary to transform the measured coordinates successfully into standard coordinates by a process that involves no sophisticated model for the plate. Using external checks we estimate the increase in accuracy to be of the order of 25 per cent.     

Near‐surface hydraulic conductivity of northern hemisphere glaciers

The hydrology of near‐surface glacier ice remains a neglected aspect of glacier hydrology despite its role in modulating meltwater delivery to downstream environments. To elucidate the hydrological characteristics of this near‐surface glacial weathering crust, we describe the design and operation of a capacitance‐based piezometer that enables rapid, economical deployment across multiple sites and provides an accurate, high‐resolution record of near‐surface water‐level fluctuations. Piezometers were employed at 10 northern hemisphere glaciers, and through the application of standard bail–recharge techniques, we derive hydraulic conductivity (K) values from 0.003 to 3.519 m day^?1, with a mean of 0.185 ± 0.019 m day^?1. These results are comparable to those obtained in other discrete studies of glacier near‐surface ice, and for firn, and indicate that the weathering crust represents a hydrologically inefficient aquifer. Hydraulic conductivity correlated positively with water table height but negatively with altitude and cumulative short‐wave radiation since the last synoptic period of either negative air temperatures or turbulent energy flux dominance. The large range of K observed suggests complex interactions between meteorological influences and differences arising from variability in ice structure and crystallography. Our data demonstrate a greater complexity of near‐surface ice hydrology than hitherto appreciated and support the notion that the weathering crust can regulate the supraglacial discharge response to melt production. The conductivities reported here, coupled with typical supraglacial channel spacing, suggest that meltwater can be retained within the weathering crust for at least several days. Not only does this have implications for the accuracy of predictive meltwater run‐off models, but we also argue for biogeochemical processes and transfers that are strongly conditioned by water residence time and the efficacy of the cascade of sediments, impurities, microbes, and nutrients to downstream ecosystems. Because continued atmospheric warming will incur rising snowline elevations and glacier thinning, the supraglacial hydrological system may assume greater importance in many mountainous regions, and consequently, detailing weathering crust hydraulics represents a research priority because the flow path it represents remains poorly constrained.     

Transient bacterial contamination of the dual-porosity aquifer at Walkerton,Ontario, Canada

Contamination of the Paleozoic carbonate aquifer at Walkerton (Ontario, Canada) by pathogenic bacteria following heavy rain in May 2000 resulted in 2,300 illnesses and seven deaths. Subsequent tracer testing showed that there was rapid groundwater flow in the aquifer, and also rapid exchange between the aquifer and the ground surface. Electrical conductivity (EC) profiling during a 3-day pumping test showed that most flow was through bedding-plane fractures spaced about 10 m apart, that there were substantial contrasts in EC in the major fracture flows, and that there were rapid changes over time. Total coliform sampling revealed transient groundwater contamination, particularly after heavy rain and lasting up to a few days. These characteristics can be understood in terms of the dual-porosity nature of the aquifer. Most of the storage is in the matrix, but this can be considered to be static in the short term. Almost all transport is through the fracture network, which has rapid groundwater flow (～100 m/day) and rapid transmission of pressure pulses due to the high hydraulic diffusivity. Rapid recharge can occur through thin and/or fractured overburden and at spring sites where flow is reversed by pumping during episodes of surface flooding. These characteristics facilitated the ingress of surface-derived bacteria into the aquifer, and their rapid transport within the aquifer to pumping wells. Bacterial presence is common in carbonate aquifers, and this can be explained by the well-connected, large-aperture fracture networks in these dual-porosity aquifers, even though many, such as at Walkerton, lack karst landforms.     

The analysis of drainage network composition

The Horton method of analyzing drainage network composition is reviewed, with the conclusion that it has not been very effective either in improving understanding or in developing useful methods of characterizing drainage basins. New methods which are based on the link rather than the Horton (or Strahler) stream are described. A number of detailed examples of the application of these new methods to the topologic and geometric properties of networks are provided. The results are compared with the predictions of the random model. Data used in the analysis were obtained from 1:24,000 U.S.G.S. topographic maps of eastern Kentucky. Thirty drainage basins were selected and their channel networks were outlined first by the contour-crenulation (CC) method and then by another, more objective, method (SC) in which stream sources were identified by a quantitative slope criterion. The CC and SC samples comprise about 8,700 and 1,700 links, respectively. The three most important results of the analysis are: (1) the channel networks are slightly but significantly more elongated than predicted by the random model, (2) there are fewer second magnitude links than predicted, and (3) the length distribution for interior links depends upon the kind of link (interior or exterior) joined downstream. These features are found in both CC and SC networks.     

Applications of the random model of drainage basin composition

The random model of drainage basin composition is founded on the assumptions that (a) natural channels are topologically random in the absence of geological controls and (b) for channel networks developed in similar environments, the exterior and interior link lengths are independent random variables with a common distribution for each type. The effectiveness of this model in estimating the values of geomorphic variables and in explaining and predicting geomorphic relationships is illustrated by several examples. The data required for these examples were obtained from map studies of 30 channel networks, comprising a total of about 8700 links, in eastern Kentucky. A common factor in the success of all three applications of the model is the way in which the planimetric features of drainage basins are determined by their underlying topologic structure.