Abstract:
Shallow lakes are ecologically and economically important; many users are interested in methods to assess their response to restoration measures and in tools to predict the impact of specific measures. These users include: local and governmental authorities, private companies
or nature conservation organisations.
This research is centred on the Broads. The Broads are shallow, eutrophic lakes, probably the result of medieval peat workings, concentrated in the Ant, Bure, Thurne and Yare river valleys. These man made lakes and their surroundings are unique in Europe in terms of both ecology and landscape, forming one of the few remaining large areas of lowland river grassland in the UK.
A catchment scale model, SWAT, has been used to model past and future land use and
climate scenarios for river basins supplying water and nutrients to the Broads. SWAT is a
comprehensive model that requires a diversity of information including climate, topography, soil, land use, agricultural practices, water abstraction and discharge data.
Future scenarios run with SWAT suggest that increases in rainfall and temperature through
climate change and changed land use increase nutrient and sediment yields and runoff. Future scenarios therefore suggest increased eutrophication problems for both the rivers and Broads within the study area and an increase in the already high risk of ecological failure to the Broads.
Various management scenarios based on erosion control measures were designed to alleviate nutrient and sediment yields and increased run-off to the system. SWAT modelling showed the best-case future scenario in terms of land management was to convert the area to grassland. Where land is still used for agriculture erosion control, measures such as cover crops and conservation tillage should be employed.
Overall, the work has increased the understanding of water quality, water movement, nutrient and sediment dynamics and agricultural management practices within the study area. The environmental implications of different future scenarios and erosion control measures on the ecology of the Broads provide a basis for management of the area.
