Quantifying the effectiveness of a river restoration project in a small river basin on the rural-urban fringe
This thesis is an investigation of the effects of river restoration on a stream which, in the past, has undergone extensive channelization for the purposes of agricultural drainage and flood protection. Over the last two decades it has been shown that although channelization may have some benefits in terms of drainage and flood mitigation, it has a considerable detrimental effect on the ecology of a stream and its immediate environs. The purpose of the restoration was to install several engineered features along the length of the stream on the campus section and to record if these features had the expected beneficial effect on the ecology. One of the main advantages of siting the study on the Ballysally Blagh is its proximity to the University of Ulster - indeed, the stream flows partly through the campus. A Meteorological Office Meteorological Station on campus has been used to collect weather data for over 25 years. Additionally, the Ballysally Blagh has been instrumented with a hydrograph station and a v-notch weir since 1976 providing a nearly constant hydrograph record which can be used in conjunction with the meteorological data to determine if catchment behaviour is changing over time due to, for instance, continuing urbanization of the catchment, or the potential effects of climate change.
This study shows that particular types of engineered feature have been successful in terms of their effect on the stream ecology, and that others have not, and suggests why this may be so. There are also clear indications of a change to the catchment hydrological response over time. Most of these indications are that continuing urbanization is having a limited effect, and that changed weather patterns, perhaps due to long-term changes in climate, may be underpinning this effect.