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International audienceOne of the main difficulties encountered when characterizing the hydrodynamic properties of a fractured aquifer is to identify the preferential flow paths within it. Different methods may be applied to determine the variability of the permeability at the borehole scale and to image the structure of the main flow zones between boreholes. In this paper, we compare the information obtained from different measurement techniques performed in a set of three 100 m depth wells (well-to-well spacing: 5­10 m) in a fractured crystalline rock setting. Geophysical logging and borehole-wall imaging are used to identify open and closed fractures intersecting the boreholes and their orientation. The comparison with flowmeter and single packer tests shows that few of the fractures interpreted as open from geophysical logs are significantly transmissive. Cross-borehole connectivity is first investigated from single packer tests with pressure monitoring in adjacent boreholes. To determine fracture zone connectivity, we propose a methodology simply based on the variation with packer depth of the ratio of the drawdown in the observation well and the drawdown in the pumping well. The results are compared to the analysis of cross-borehole flowmeter tests. We show that both methods provide consistent results with a similar level of information on connectivity

The development of cost-effective approaches to monitor groundwater–surface-water exchange processes and contaminant fate within the hyporheic zone fundamentally underpins implementation of legislation such as the European Community Water Framework Directive, which requires integrated management of groundwater and surface water. Cost-effective mini drive-point piezometers (MDPs) and multilevel samplers (MLSs) are presented that use cheap construction materials, involve simple fabrication and installation procedures, and have a proven durability with low vulnerability to flood events and vandalism. They have been used across a range of hydro(geo)logical settings in the UK and proven to be effective in discerning flow exchange, geochemical trends, and contaminant transport and attenuation over monitored depths of 0.25 to 2 m at a resolution as low as 0.05 m. Example depth profiles, cross-river transects and river-reach longitudinal profiles from the River Tame catchment (West Midlands, UK) illustrate the value of MDP–MLS approaches in establishing surface-water–groundwater mixing zone depths, contaminant natural attenuation as a result of biotic activity within the hyporheic zone, and estimates of contaminant flux exchanges between groundwater and surface water. The MDP–MLS approaches allow discernment of contaminated groundwater plume discharges that may go undetected, or at best poorly resolved, if reliance was solely placed on conventional riverside monitoring wells and/or surface-water sampling. The MDP–MLS approaches described also have potential to be used in the investigation of shallow sediment aquifers, lake shorelines and wetland features.

Impacts of riverbed gas on the hydraulic and thermal dynamics of the 1 hyporheic zone 2

The Wildmoor Sandstone Formation, proved in three boreholes drilled at Birmingham University, is dominated by fine- to medium-grained sandstones deposited in a braided river environment, within which channel lag, channel fill and abandoned channel facies are recognized. Minor proportions of aeolian sandsheet are present, as are dolocretes, not previously reported in the formation.The sandstones are feldspathic and lithic arenites, and typically are clay-poor. Early dolomite dominates the diagenetic overprint, and is preferentially developed in channellag deposits. Burial diagenetic effects are minor. Late calcite occurs as a pore-filling phase and within fractures.Minor fractures and granulation seams are oriented parallel to the NE-SW Birmingham Fault. ‘Conventional’ granulation seams, with comminution of detrital material, and more complex seams containing comminuted dolomite cement with a millimetre-wide halo of dolomite cement are present, the latter implying that the sandstone was dolomitecemented at the time of fracturing.Several scales of heterogeneity will affect groundwater solute transport. The palaeosols and abandoned channel mudstones may act as barriers to vertical flow at the decimetre scale. Dolomite-cemented channel-lag deposits may act similarly at smaller scales. Granulation seams have permeabilities of two-three orders of magnitude lower than their host sandstones, but their limited occurrence may limit their impact on larger scale flow. Matrix permeability is controlled by grain size and dolomite cement.The fines in the fine-grained, ripple cross-laminatied sandstones were extensively washed out during coring, and this lithology may be a source of sand yields in some sandstone boreholes. Although no enhancement of particle yields was seen during packer testing, the possibility remains that more comprehensive failure may occur at higher pumping rates.

15Green roofs can potentially be used to tackle a variety of environmental problems, and 16 can be used as development mitigation for the loss of ground-based habitats. Brown 17(biodiversity) roofs are a type of green roof designed to imitate brownfield habitat, but 18 the best way of engineering these habitats requires more research. We tested the effects with larger plant coverage and diversity before the occurrence of a sequence of drought 31 disturbances, but was more strongly negatively affected by the disturbances than the 32 two less productive treatments. We suggest that this was due to the over-production of 33 plant biomass in the more productive treatment, which made the plants more vulnerable 34 to the effects of drought disturbance, leading to a kind of 'boom-bust' assemblage 35 dynamic. The 'ideal' amount of added organic matter for these green roof systems was 36 very low, but other types of green roof that have a larger water holding capacity, and/or 37 more drought resistant plant floras, will likely require more organic matter or fertiliser. 38Nonetheless, nutrient-supported productivity in green roof systems should be kept low 39 in order to avoid boom-bust plant assemblage dynamics. Research into the best way of 40 engineering green roof habitats should take place over a long enough multi-year time 41 period to include the effects of temporally infrequent disturbances. 42Keywords brown roof; development mitigation; drought disturbance; productivity 56 57 58 59 60 61 62 63 64 65 66 67 68 69

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