The impact of land-use change on the hydrological response of the River Camel, Cornwall, UK.
Abstract
The River Camel catchment, Cornwall is typical of many rural areas in Southwest England. Analysis of hydrological data for the River Camel, found that there was a considerable increase in the magnitude and frequency of high flows since the mid-1970s. Flow duration analysis of post 1983 discharge data showed increases at all levels of flow such that the 1 in 100-year flood now occurs at a 1 in 20-year frequency. Agricultural census data were analysed using a GIS to determine the amount of land-use change in the period 1965 - 2000 and to see if there was a link with the change in regime. The amount of cereals sown rose from about 16 to 33% although most of the change occurred in lowland areas adjacent to the main river. The intensity of pastoral activity rose from 3 to 5.5 livestock units ha-1 and most of the increase occurred on the higher ground of Bodmin Moor. Changes in the discharge regime were not related to changes in the frequency or magnitude distribution of daily rainfall totals. A hydrologically distributed catchment model, MIKE-SHE, was used to determine the influence of land-use change on river discharge. One limitation of the model was the large number of parameters that were required to run it. However, the advantage of running a distributed model was that the effect of the spatial disposition of different types of land-use on flooding could be investigated. The hydraulic properties of the soil representing particular parcels of land were modified to reflect the changes caused by different agricultural activities. The study concluded that for a medium sized and predominantly rural catchment such as the Camel, gradual changes in land-use brought about by intensive agriculture, particularly following the introduction of maize, played a significant and quantifiable role in affecting the hydrological regime. The correlation between the model simulation and the flow record was good.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....6517W