Controls on the discharge of Chalk streams of the Berkshire Downs, UK

This paper presents the results of a two-year field campaign to determine the spatial and temporal variability of groundwater interaction with surface waters in two Cretaceous Chalk catchments (the Pang and Lambourn) in the Upper Thames in Berkshire, UK, based on measurement of dissolved carbon dioxide (CO 2 ). Average stream water concentrations of dissolved CO 2 were up to 35 times the concentration at atmospheric equilibrium. Mean groundwater concentrations of 85 and 70 times the atmospheric equilibrium were determined from borehole water sampled in the Pang and Lambourn respectively. Diurnal and seasonal variation of in-stream concentration of dissolved CO 2 is not significant enough to mask the signal from groundwater inputs.

Section: Methods and Analysissupporting

confidence: 94%

Section: L1mentioning

confidence: 99%

Variability of dissolved CO<sub>2</sub> in the Pang and Lambourn Chalk rivers

Griffiths

Nutter

Binley³

et al. 2007

“…Due to the highly permeable nature of the Chalk, both the Pang and the Lambourn are primarily groundwater fed but an exact water balance is difficult to assess because of uncertainty over the groundwater flow pathways and the possibility of bypass mechanisms (Bradford, 2002).…”

Section: Hydrological Settingmentioning

confidence: 99%

The water quality of the LOCAR Pang and Lambourn catchments

Neal

Jarvie

Wade

et al. 2004

The water quality of the Pang and Lambourn, tributaries of the River Thames, in south-eastern England, is described in relation to spatial and temporal dimensions. The river waters are supplied mainly from Chalk-fed aquifer sources and are, therefore, of a calcium-bicarbonate type. The major, minor and trace element chemistry of the rivers is controlled by a combination of atmospheric and pollutant inputs from agriculture and sewage sources superimposed on a background water quality signal linked to geological sources. Water quality does not vary greatly over time or space. However, in detail, there are differences in water quality between the Pang and Lambourn and between sites along the Pang and the Lambourn. These differences reflect hydrological processes, water flow pathways and water quality input fluxes. The Pangs pattern of water quality change is more variable than that of the Lambourn. The flow hydrograph also shows both a cyclical and uniform pattern characteristic of aquifer drainage with, superimposed, a series of flashier spiked responses characteristic of karstic systems. The Lambourn, in contrast, shows simpler features without the flashier responses. The results are discussed in relation to the newly developed UK community programme LOCAR dealing with Lowland Catchment Research. A descriptive and box model structure is provided to describe the key features of water quality variations in relation to soil, unsaturated and groundwater flows and storage both away from and close to the river.

“…These tubes were changed every four weeks, and sent to an accredited commercial laboratory for analysis. The protocol for the NO 2 tubes was that used for the UK National Network (Bush et al, 2000), that for the ammonia tubes was based on information in Sutton et al (2001).…”

Section: Chlorophyll-amentioning

confidence: 99%

“…l There is a lack of certainty over the regional groundwater routing and the catchment, given that it is permeable and is therefore not water tight. Thus, there is uncertainty over the water balance (Bradford, 2002). l The river waters drain a Chalk aquifer with residence times of the order of decades.…”

Section: The Accuracy and Meaning Of Input Output Relationships: Stramentioning

confidence: 99%

Rainfall and runoff water quality of the Pang and Lambourn, tributaries of the River Thames, south-eastern England

Neal

Skeffington

Neal

et al. 2004

Rainfall and runoff water quality of the Pang and Lambourn, tributaries of the River Thames, south-eastern England 601 Hydrology and Earth System Sciences, 8(4), 601613 (2004) AbstractThe water quality of rainfall and runoff is described for two catchments of two tributaries of the River Thames, the Pang and Lambourn. Rainfall chemistry is variable and concentrations of most determinands decrease with increasing volume of catch probably due to wash out processes. Two rainfall sites have been monitored, one for each catchment. The rainfall site on the Lambourn shows higher chemical concentrations than the one for the Pang which probably reflects higher amounts of local inputs from agricultural activity. Rainfall quality data at a long-term rainfall site on the Pang (UK National Air Quality Archive) shows chemistries similar to that for the Lambourn site, but with some clear differences. Rainfall chemistries show considerable variation on an event-to-event basis. Average water quality concentrations and flow-weighted concentrations as well as fluxes vary across the sites, typically by about 30%. Stream chemistry is much less variable due to the main source of water coming from aquifer sources of high storage. The relationship between rainfall and runoff chemistry at the catchment outlet is described in terms of the relative proportions of atmospheric and within-catchment sources. Remarkably, in view of the quantity of agricultural and sewage inputs to the streams, the catchments appear to be retaining both P and N.