MSc & MSc Funded Theses
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Browsing MSc & MSc Funded Theses by Supervisor "Holman, Ian P."
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Item Open Access An investigation into illegal discharge of sewage from boats in the broads(Cranfield University, 2008-09) Hardwick, Susannah; Holman, Ian P.In response to concerns expressed by the Environment Agency and Broads Authority, this project aimed to assess the risk of illegal sewage discharge from boats into the waterways of the Broads, East Anglia. The Broads are an internationally important wetland, consisting of marshes, fenland, rivers and shallow lakes. A popular area for boating, sewage discharge from boats could have deleterious impacts on the environment, health and public perception. Water was tested for evidence of faecal pollution at a mooring site at Thorpe Island, River Yare, identified as at risk from illegal sewage disposal from boats. Continuous monitoring of ammonia, ammonium and dissolved oxygen up and downstream of the moorings took place at half hourly intervals over six weeks. Thermotolerant coliforms, ammonia, phosphorous and dissolved oxygen were manually sampled at Thorpe Island and nearby Whitlingham sewage treatment works. Definitive evidence of pollution from boats was not found, either sewage was not illegally discharged during the study period, or methods were inadequate to identify the occurrence of faecal pollution with certainty. The distribution of sewage disposal facilities available for boats was also analysed. The navigable waterways of the Broads were categorised in terms of the risk of illegal sewage disposal due to distance from disposal facilities. The south eastern reaches of the River Bure and western reaches of the River Waveney were identified as being at most risk. Recommendations are made to identify areas of the Broads at risk from pollution due to factors other than distance from sewage disposal facilities. Any further water quality studies should be carried out in these areas and improvements to the methods are suggested. Future management should include raising awareness of boaters about issues surrounding sewage disposal and the consideration of the provision of either mobile or static sewage disposal facilities in areas where current provision is deemed inadequate.Item Open Access Investigation into the spatial distribution of salt loads into the Upper Thurne SAC and likely timescales for response to management controls(Cranfield University, 2013-08) Heward-Mills, Christine; Holman, Ian P.The Upper Thurne Broads (shallow lakes) in the Norfolk Broads are sites of international conservation importance. The protected aquatic species of these lakes are currently threatened by poor water quality, largely due to discharges of saline water from the Brograve land drainage pump, which maintains groundwater levels on adjacent marshlands below sea level. The lowering of water table levels by drainage has caused seawater to intrude into the coastal aquifer and salinise the groundwater and drain network. Through surveying salt concentrations and flow regimes in the drains of the coastal marshes and analysis of telemetry data from the land drainage pumps, this thesis investigates 1) the spatial distribution of the salt loading into the drain system in order to identify where management changes should be targeted and 2) assesses whether changes to the water level management in a nearby drainage area have had any impact on the salt load that is discharged from the pump. Research has shown an uneven distribution of salt loading across the coastal marshes. These differences appear to be driven by the nature of the drain-aquifer interaction in the individual marshes and the relative gradient differential produced between the marsh drainage ditches and the main drain at times of pump activity. The research indicates that restoration of the Upper Thurne water quality will necessitate scaling down water table level management to individual marshlands in order to ensure efficacy of measures. It also makes recommendations for further research to be carried out in the study area. There is insufficient data at the time of writing to suggest that raising water levels in an adjacent marshland has conclusively reduced saline discharges from the pumps since management controls were implemented. However, some lowering of salt concentrations was observed which appear to be distinct from climatic influences.Item Open Access The summer nutrient dynamics of Bosherston lakes, Pembrokeshire, and the potential impacts of future climate and policy change(Cranfield University, 2008-09) Niciecki, Georgina; Holman, Ian P.Bosherston Lakes, Pembrokeshire have had problems with high nutrient concentrations and algal blooms, particularly in the stream-fed Eastern Arm, leading to the loss of Chara within the Eastern Arm. Management in the last 25 years has led to a reduction in external nutrient loading, but the impact of internal loading during the summer has yet to be properly assessed. The potential impacts of climate and policy change on the nutrient dynamics need to be accounted for to be able to efficiently manage the site in the future to preserve the important Chara habitat. The streams and lake water were analysed for both Total Reactive Phosphorus (TRP) and Total Phosphorus (TP) and Nitrate and Total Nitrogen. The sediment in the lakes were analysed for TRP and TP only. Phosphorus release from sediments and the impact of future temperature changes were assessed through laboratory experiments. It was found that the lakes are still suffering from elevated nutrient levels during the summer. The main source of phosphorus to the lakes in the summer is probably through internal phosphorus release from the lake sediments. The Eastern Arm is the most affected by internal loading. The main sources of nitrates to the lakes are from the streams and groundwater. It was found that phosphorus release increased with increasing temperature. There are many uncertainties but future climate changes are likely to increase both nutrient and sediment loading and it is unlikely that the water quality in the Eastern Arm will improve sufficiently to accommodate Chara. The introduction of an NVZ is unlikely to be counterproductive in terms of reducing N:P ratios and will help decrease nitrate levels in the lakes and streams, some of which are nearing the safe drinking water limits. Future management should target phosphorus loaded sediment entering the lakes in the winter and contributing to the phosphorus concentration in the lake water during the summer when phosphorus is released. The sediment traps in the catchment should be maintained or enhanced and weed cutting should be continued if it is found to have no adverse ecological effects.