Area separation of streamflow in an upland catchment with partial peat cover

The problem considered here is: how to measure the discharge from a raised min in terrain that is only partly mire-covered. The approach involves comp arison of the stream discharge from a mixed mire and mineral-soil sub-catch ment with that from a neighbouring non-mire sub-catchment. Inconclusive res ults have previously been obtained using naturally occurring chemical trace rs, and the validity of an alternative area-separation method is now examin ed. Estimates of the mire component of discharge derived in this way and summed over periods of 7-12 days agree to within 1 mm day(-1) with estimates of m ire discharge obtained by two other methods, namely direct measurement usin g mire lysimeters, and water-balance calculations using on-site rainfall me asurements and evapotranspiration data calculated using the Penman-Monteith formula. The area-separation method may, therefore, be a useful adjunct or alternative to more expensive chemical methods for studying both the water yield of mixed catchments and aspects of peatland hydrology. (C) 1999 Else vier Science B.V. All rights reserved.