Are headwaters just the sum of hillslopes?

Until recently, there have been few attempts to link hillslope, headwater and meso-scale hydrology. However, the paper by Shaman et al. (2004, Hydrological Processes18: 3195–3206) has proposed concepts that link headwater and meso-scale basins. Although their paper provides an excellent example of how we should make connections between small- and large-scale hydrology, the analysis still lacked sufficient consideration of the spatial variability of hydrological behaviour at the hillslope/headwater scale. Here, we extend the discussion of Shaman et al. to smaller sized catchments. We use detailed datasets of hydrometric and hydrochemical measurements collected at the hillslope and small catchment scale at the Fudoji and Ibi catchments in Japan. We show that: (1) large spatial variation in the hydrological responses is present at the hillslope scale and that these responses are strongly controlled by the contribution of water flow from the bedrock into the soil at baseflow; (2) the spatial variability of hydrological responses in headwaters is damped compared with that of the hillslope, and this damping is determined by the integration of the hillslope responses which largely occurs in the stream. Copyright © 2005 John Wiley & Sons, Ltd.

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