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My research related to an in-depth investigation of catchment management in the context of Drinking Water Safety Plans, the principal aims of which were to: 1) Establish to what extent catchment management had been implemented in England and Wales, in both historic and current contexts; 2) Identify the roles, remits and activities of the key stakeholders in catchment management in England and Wales; 3) The extent to which climate change could affect future catchment management; and 4) Determine the ability of catchment management to facilitate Drinking Water Safety Planning in Wales, and to identify any scope for possible improvement. The requisite literature review was necessarily exhaustive and resource-intensive, and encompassed the following subject headings: • Water resources; • Water quality; • Climate change; • Catchment management; • Public water supplies; • Private water supplies; • Stakeholder engagement; • Regulatory (at the European, national and devolved levels) and management models; and • Governance issues. As the catchment is at the top of the drinking water supply chain, if we address water quality and quantity problems there, the result is a cleaner, cheaper, more secure product for the consumer. Consequently, I decided to develop an Abstraction Safety Index - along with an associated catchment environmental assessment methodology - for determining the overall environmental quality of water within a catchment, and for expressing this quantitatively. This mathematical index has been subject to peerreview by water companies and other environmental stakeholders. The index was calibrated using a range of different types of catchments - used for both private water supply and public water supply purposes - and it was subsequently used to consider a number of alternative conceptual scenarios, to determine how changes to regulatory, legal and institutional models could feasibly affect the environmental quality of catchments in Wales, in order to improve the quality of abstracted water.

The implementation of the EU Water Framework Directive (2000/60/EC) (WFD), enacted to monitor and recover the quality of water bodies, is a good example of catchment management requiring a wider scope of understanding with regard to the chemical, ecological and quantitative status of river catchments. It has caused water management to shift from a local to a river basin scale and therefore requires a better understanding of emission sources of dangerous substances and their contribution to water quality at the catchment level. Metals include dangerous substances of continued and growing concern. The hazardous properties of metals reflect their ability to substitute for essential elements in biological systems, resulting in a disturbance of the biological functions of animals and humans. This thesis aimed to identify ways of assessing sources of metals at the catchment level for the implementation of the WFD. Different approaches were proposed to estimate impacts of emission sources on levels of metals in water bodies. Potential anthropogenic sources of metals and metalloids in receiving waters were identified at the catchment level. Of the metal sources, effluents from wastewater treatment plants, sediments in a water body and diffuse metal sources were selected in order to further evaluate their contributions to the quality of water bodies, using or developing simple methods to estimate these. Case studies demonstrated the effectiveness and reliability of the calculations used. Overall findings of the work highlighted the need to identify all the pressures of pollutant inputs and to assess their relative importance to the deterioration of water quality for compliance with the WFD. To this end, it is recommended that source assessment should be incorporated into the process of river basin management under the WFD. Source assessment can facilitate the performance of water management stages and the improvement of the quality of surface water bodies.

The intention of this study was to investigate the two most significant sources of dissolved organic carbon (DOC) to drinking water supplies; peatlands and algae. For two drinking water reservoirs in north Wales, Llyn Cefni and Llyn Alaw, markedly different seasonal trends were recorded, and these were linked to contrasting aspects of the lake's catchment and the meteorological conditions experienced during the two surveys. For Llyn Cefni, the DOC signatures for the inflowing streams and lakes correlated significantly, Afon Erddreiniog (R2=0.585, p<0.01) and Afon Cefni (R2=0.784, p<0.001), indicating a strong flux of terrestrial DOC into the lake from a nearby peatland. Much less of a seasonal trend in DOC was recorded at Llyn Alaw, with concentrations averaging 10.7 mg L 1, reflecting the absence of a peaty catchment. DOC derived from autochthonous production was also shown to be influential. Both lakes experienced nitrate depletion during the summer of the surveys, falling from 12.7 mg L-1 in Llyn Cefni and 6.5 mg L"' in L lyn Alaw to undetectable levels, suggesting extreme eutrophy, although the lack of detectable phosphate at Llyn Alaw may be why the growth of algal blooms was much less prevalent than at Llyn Cefni. A new type of floating constructed wetlands (FCW) was shown to Offer a potential solution 'to the production of algal blooms in the reservoirs, whereby over a four-week period, the FCWs were able to reduce algal growth by 80%, through sequestration of the key nutrients nitrate and phosphate and possibly due to the direct inhibitory properties of phenolic compounds on the algae. Furthermore, it was discovered that 8 Phragmites aus/ralis plants is the ideal number to maximise nutrient uptake and minimise algal growth in 70 litres of water. Studies in Finland and Malaysia were undertaken to highlight the importance of peatland management practices, as' vast areas of the world's boreal and tropical peatlands have been drained for agricultural purposes. The study in Finland showed that although there was noconsistent response in DOC export potential with drainage across the sites of contrasting nutrient status, a significant correlation was observed between DOC and the water content of the soil, R2 = 0.59 (p< 0.001), indicating that as the water-table height falls the DOC export potential of the soil increases. It was also considered that the trend in DOC is driven by changes in soil pH and the resulting suppression of the key carbon regulating enzyme phenol oxidase; where acidity has increased following drainage phenol oxidase activity has declined and the concentration of DOC released has increased, conforming the view that phenol oxidase acts as an `enzymic latch' in peatlands. The study in Malaysia recorded a 40% greater export potential of DOC from the oil palm soil and more than twice the DOC concentration in drainage waters compared to the undisturbed peat soil. The activity of the key hydrolytic enzyme ß-glucosidase was 25% higher in the oil palm soil than the undisturbed peat. This may be due to an improved soil organic matter quality at the oil palm site and suggests that increased activity of this enzyme may have been crucial for mobilising DOC from the soil matrix. The repercussions of these studies are discussed with emphasis on the potential impacts of a changing climate.

Water colour is the naturally occurring yellow-brown 'tea like' discolouration which can be observed in freshwaters, and is typically composed of high molecular weight organic carbon. Water discolouration is a major problem for the water industry as over the past 30 years, water colour release has more than doubled, greatly increasing treatment costs and making land management a more feasible option for improving water quality. This project was developed in conjunction with Yorkshire Water Plc, to investigate the mechanisms of water colour production, and the implications that these mechanisms have for land management to improve water quality. In particular, the study aimed to identify the key relationships between drainage water quality and quantity, soil processes and vegetation type that are pivotal to the understanding of water discolouration.

This thesis reports the results of a three year cross disciplinary investigation of the water resources of a small headwater catchment and their role existing and future in the livelihoods of the local community. In addition the potential for micro-catchment management to improve the water resources and water based livelihoods of the catchment community was also examined. Physical examination of the shallow aquifer revealed higher than expected levels of groundwater recharge, matched by high levels of naturally occurring discharge. A groundwater modelling study suggested that this discharge was caused by both deep and shallow rooted vegetation, rather than by drainage losses, and that the catchment aquifer was largely isolated from any larger regional groundwater system. Research into the historical development of the catchment community revealed an ongoing process of agricultural intensification, driven by increasing population and expectations. One manifestation of this intensification is a rapid development of groundwater resources for small scale irrigation. The study suggested that the increased development of and reliance on water points exploiting shallow groundwater resources could lead to increased risk in dry periods associated with generally low groundwater levels. The work highlighted the crucial importance of correct siting and design of water points if widespread failure is to be avoided. However, it also suggested that irrigated agriculture could be sustainably increased at least ten-fold by using suitably sited high yielding water points. Finally, a prototype decision support system was developed using Bayesian Belief Networks, and this was used to integrate the physical and human aspects of the study within a single framework. This framework was then used to examine the likely affects on livelihoods of adopting a micro-catchment management approach to managing groundwater resources.