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Title: The role of blanket peat moorland management in the generation and amelioration of discolouration of surface water supplies
Author: O'Brien, Helen Elizabeth
Awarding Body: Nottingham Trent University
Current Institution: Nottingham Trent University
Date of Award: 2009
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Abstract:
Discolouration of surface waters in upland catchments (with associated costs of water treatment and resources) has increased particularly since the severe droughts in the 1970s and mid 1990s. Such discolouration is a major concern for many water companies whose catchment areas include upland moorland, particularly those areas located on deep blanket peat soils. The principal aim of this study was to evaluate the role of catchment management in the production of discoloured surface runoff and DOC flux from catchments used as gathering grounds for public water supply. The investigation focused on blanket peat moorlands in the Ladybower catchment from which water is treated at Bamford Treatment Works. Whilst other workers have considered management techniques for water colour amelioration at laboratory and plot scale, no previous study had evaluated the impact of these approaches at a catchment scale with a sufficient degree of experimental control. Baseline relationships between meteorological inputs and hydrological responses were established during a calibration period prior to intervention in management. Six catchments were instrumented and the relationships between water discolouration and hydrological and land management characteristics were identified. Suitable pairings of catchments were determined with similar characteristics. One catchment was then treated to a management practice, whilst the management on another was not affected. It was then possible to assess the impact of management on the treated catchment in comparison with the untreated catchment. Following controlled intervention in management on three of the catchments (gullies blocked, cessation of burning and removal of grazing), all study sites were monitored for a further three years to identify and quantify changes in hydrological response, water discolouration and DOC flux and predict responses post-management intervention. The results found that water colour and DOC flux increased on all catchments irrespective of changes in land management, although in the final year there was some recovery. On the paired control sites, where management was not manipulated and similar meteorological conditions prevailed; there were no statistically significant changes from that predicted for true colour and runoff. On the manipulated catchments there were significant changes from that predicted by the control which suggests that management practices contributed to changes on these catchments. Whilst the true colour increased at the gully-blocked site (p = 0.09), the observed colour was lower than predicted on the catchments where burning had ceased (p = 0.891) and grazing was removed (p<0.01). On all catchments there was a reduction in runoff and DOC flux from that predicted; significant at the gully-blocked catchment and where grazing was removed (p<0.01), but where burning ceased the change was only weakly significant (p = 0.085) or not significant (p = 0.4) respectively. Although the results have identified changes in hydrological conditions and colour/DOC response following the manipulation of practices, there is an on-going need for investigation of longer term effects of such interventions, to identify sustainable catchment management practices and to ameliorate further deterioration of surface water quality.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.510263  DOI: Not available
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