“…They range in complexity from the so-called 'physically based fully distributed' (Wigmosta et al, 1994;Abbott et al, 1986;Garrote and Bras, 1995;Julien et al, 1995) to 'semi-distributed' (Boyle et al, 2001;Obled et al, 1994;Schumann, 1993), and to conceptual lumped rainfall-runoff models applied at smaller scales (Michaud and Sorooshian, 1994;White, 1988). In terms of computational elements, they may be built on grid (Ogden and Julien, 1994;Kouwen and Garland, 1989), small sub-basins (Carpenter et al, 2001;Obled et al, 1994), triangulated irregular network (TIN) (Goodrich et al, 1991) and stream tubes (Grayson et al, 1992;Moore and Grayson, 1991). Recently, efforts have been undertaken to account for the effects of 'sub-grid' heterogeneity on hydrologic processes Beven, 1995).…”