High temporal resolution in situ measurement of the effective particle size characteristics of fluvial suspended sediment.

This paper reports the use of a LISST-100 device to monitor the effective particle size characteristics of suspended sediment in situ, and at a quasi-continuous temporal resolution. The study site was located on the River Exe at Thorverton, Devon, UK. This device has not previously been utilized in studies of fluvial suspended sediment at the storm event scale, and existing studies of suspended sediment dynamics have not involved such a high temporal resolution for extended periods. An evaluation of the field performance of the instrument is presented, with respect to innovative data collection and analysis techniques. It was found that trends in the effective particle size distribution (EPSD) and degree of flocculation of suspended sediment at the study site were highly complex, and showed significant short-term variability that has not previously been documented in the fluvial environment. The collection of detailed records of EPSD facilitated interpretation of the dynamic evolution of the size characteristics of suspended sediment, in relation to its likely source and delivery and flocculation mechanisms. The influence of measurement frequency is considered in terms of its implications for future studies of the particle size of fluvial suspended sediment employing in situ data acquisition.

The role of web-based environmental information in urban planning--the environmental information system for planners.

The Environmental Information System for Planners (EISP) is a proof of concept web-based system designed to support decision making within the UK planning framework by making information on environmental issues more widely accessible. It incorporates relevant outputs from the Natural Environment Research Council (NERC) Urban Regeneration and the Environment (URGENT) research programme and from research directly commissioned by the Office of the Deputy Prime Minister (ODPM). It supports three principal planning functions carried out by local authorities: pre-planning enquiries, development control decisions and strategic planning. Eleven environmental science themes are incorporated: Air quality, Shallow undermining, Landslide susceptibility, Groundwater protection, Flood risk, Drainage, Land contamination, Proximity to landfill, Biodiversity, Natural and Man-made heritage. Decision flow diagrams represent detailed analysis of workflow in each theme, taking account of best practice, regulatory responsibilities and planning guidance. Industry-standard web technologies integrate the flows and provide access to the system via secure web pages. Underpinning the system is an environmental geographical information system (GIS) containing up-to-date data, information and models relevant to each theme. The modular system design allows new legislation and local priorities and datasets to be easily incorporated. Web technology delivers information and research data that have hitherto been difficult for the non-specialist to access and have therefore been under-exploited. The study has demonstrated a successful application of the principles of e-Governance in an area where informed decisions commonly require specialist information. The system, if rolled out nationally, offers potential economic benefits and efficiency savings for both planners and developers.

The influence of storm events on fine sediment transport, erosion and deposition within a reach of the River Swale, Yorkshire, UK.

The spatial and temporal dynamics of suspended sediment fluxes through a 55 km reach of the lowland River Swale, Yorkshire, UK are investigated for the period July 1994-June 1996. Seventeen storm events were monitored, each of which produced significant suspended sediment transport. Variations in sediment flux dynamics and reach sediment storage through events, representing a combination of channel bed erosion and/or deposition, bank erosion and floodplain deposition, were observed. Some, but not all, of this variation can be explained in terms of event size, precipitation distribution and intensity, and antecedent sediment storage conditions. In particular, marked variations in the size of the reach sediment store over the extremely wet 4-month winter period from December 1994 to April 1995 are demonstrated. Net sediment loss from the reach took place over during this winter period. These event-scale and seasonal patterns form a background to annual variations in the catchment sediment budget.