1. From concept to commissioning

Hardcastle, Ben J.

doi:10.1680/tgs.00605.0002

Cited by 6 publications

(2 citation statements)

References 4 publications

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“…Flow gauges have been maintained at East Shefford, Welford and Shaw; and on the Winterbourne Stream at Bagnor (Figure 1). A total of 43 boreholes, intended for abstraction but rarely used, and 67 observation boreholes were drilled in the catchments of the Pang and Lambourn between 1967 and 1974 for the WBGS (Brettell, 1971;Hardcastle, 1978), and the groundwater 2038 T. R. GRAPES, C. BRADLEY AND G. E. PETTS Figure 1. The Lambourn catchment, illustrating the local geology, the extent of the surface-water catchment, location of gauging and current meter stations and position of principal dry valleys level records from these and other boreholes enable the groundwater catchment to be estimated.…”

Section: The River Lambourn Berkshirementioning

confidence: 99%

Dynamics of river–aquifer interactions along a chalk stream: the River Lambourn, UK

Grapes

Bradley

Petts

2005

Hydrological Processes

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Abstract:This paper describes the spatial and temporal pattern of groundwater flow accretion to the River Lambourn, a 234 km 2 chalk catchment of the West Berkshire Downs, UK, which has been largely unaffected by groundwater abstraction. Variations in the discharge measured at four fixed gauges in the catchment, coupled with information on the length of flowing channel over the period [1983][1984][1985][1986][1987][1988][1989][1990][1991][1992][1993][1994][1995][1996][1997][1998][1999][2000][2001], are used to describe regional patterns in flow accretion. Mean catchment accretion generally exceeds 0Ð15 m 3 s 1 km 1 , but there are significant differences between perennial reaches indicating how the combination of local structural controls and seasonal changes in the drainage net affect flow accretion. Data from current meter surveys were used to determine the spatial variability in flow accretion: 505 paired observations along 12 reaches between 1 and 2Ð95 km in length indicated a consistent spatial trend in accretion. Accretion was high in upstream and downstream channel reaches, and in middle reaches where dry valleys intersected the main valley. A flow accretion index was developed to describe the relationship of flow accretion in each of the 12 study reaches to catchment discharge. The relationship varied from a strong positive correlation with catchment discharge (two reaches), a weak positive correlation (three reaches), a strong negative correlation (two reaches), to no relationship to catchment discharge (four reaches). The results highlight the need to reconsider the usual assumption of uniform, or uniformly increasing, flow accretion in chalk catchments. Moreover, they emphasize the importance of catchment topography, and illustrate how flow accretion in individual reaches may vary between high and low groundwater levels.

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Section: The River Lambourn Berkshirementioning

confidence: 99%

Dynamics of river–aquifer interactions along a chalk stream: the River Lambourn, UK

Grapes

Bradley

Petts

2005

Hydrological Processes

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“…He also mowed the banks for access, left uncut vegetation at the water's edge for emerging insects and controlled the growth of overhanging trees and bushes, which can tangle fishing lines. During this period, the R. Lambourn was the subject of very detailed hydrological studies as a result of a proposal to develop the groundwater resources of the catchment (Hardcastle, 1978). Concern over possible changes to the discharge regime and consequences for the trout fishery led to the funding of ecological studies on the macrophytes, macroinvertebrates and fish populations.…”

Section: Introductionmentioning

confidence: 99%

Response of the flora and macroinvertebrate fauna of a chalk stream site to changes in management

et al. 2003

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SUMMARY 1. Temporal changes in a series of habitats and their macroinvertebrate assemblages were examined on a 50‐m section of a chalk stream in Berkshire, England between June 1975–79 and June 1997–2001. 2. The site was part of a trout fishery in 1975–79, when river management included instream weed cutting together with control of bankside trees and riparian vegetation. Management ceased in the 1980s and by 1997–2001, the site was heavily shaded by trees and riparian vegetation. 3. The mean area of instream macrophytes decreased by 50% between the first and second sampling period. In contrast, gravel and silt increased and invading marginal vegetation formed a new habitat. 4. Changes in macroinvertebrate family richness between sampling periods were scale dependant. Although there were, on average, significantly more families in individual replicates in 1975–79 than in 1997–2001, total family richness for the site in each year did not differ significantly between sampling periods. 5. Sixty families of macroinvertebrates were recorded during the study, 50 in both sampling periods, 53 in 1975–79 and 57 in 1997–2001. This small increase in site family richness may be due to the invading marginal plants. 6. Total macroinvertebrate abundance was significantly lower in the second sampling period. A major drought in 1976 resulted in significantly higher densities of macroinvertebrates, partly through the exploitation of epiphytic diatoms by chironomid larvae. A drought in 1997 failed to elicit a similar response because of the limited macrophytes and diatoms under heavy shading by trees and marginal vegetation. 7. Significant increases in important shredders and decreases in some scrapers between the early and later sampling years largely reflected changes in available food resources. 8. Whereas macroinvertebrate family richness has been conserved under the recent ‘no management’ regime, the site is now less attractive as a fishery because of poor access and lower densities of some macroinvertebrates taken by brown trout.

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Ecological effects of groundwater pumping and a natural drought on the upper reaches of a chalk stream

Wright

Berrie

1987

Regul. Rivers: Res. Mgmt.

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The ecological effects are examined of a three-month test of a groundwater pumping scheme, which augmented flow in a chalk stream in autumn 1975. The impact on the macrophytes and invertebrates in the upper perennial stream which received pumped water were found to be minimal.After pumping ceased, a dry winter and spring led on to a major drought in summer 1976. This prompted operational use of the groundwater pumping scheme in late summer 1976 prior to heavy winter rains which resulted in a return to the normal pattern of discharge in 1977. The ecological effects of the drought, the operational pumping and its aftermath are assessed on three channel reaches: the intermittent zone of the stream, which remained dry throughout 1976; the upper perennial channel where changes in flow regime were most severe; and the lower perennial section of the stream.Drying of the intermittent section for over one year had more severe effects on the invertebrates and fish populations than on the macrophytes, which recovered rapidly after the return of flow. In the upper perennial section, the drought led to siltation of the river-bed, loss of macrophytes and limited habitat diversity for the invertebrate fauna. Further downstream, effects were still detectable, though less severe.Operational pumping brought immediate benefit to the perennial stream by increasing the river width, removing silt and encouraging growth of macrophytes, which provided habitat and food resources for invertebrates. However, in the upper perennial reach, where siltation and loss of macrophytes had been severe, regrowth of macrophytes was slow and the effects of the drought on both macrophytes and invertebrates were still apparent in autumn 1977. It is proposed that a pumping policy that maintains river flow above the level at which siltation and subsequent loss of macrophytes occurs could minimize undesirable ecological effects of extreme low flows.

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1. From concept to commissioning

Cited by 6 publications

References 4 publications

Dynamics of river–aquifer interactions along a chalk stream: the River Lambourn, UK

Dynamics of river–aquifer interactions along a chalk stream: the River Lambourn, UK

Response of the flora and macroinvertebrate fauna of a chalk stream site to changes in management

Ecological effects of groundwater pumping and a natural drought on the upper reaches of a chalk stream

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