Abstract:Nonlinear dynamics and spatial variability in hydrological systems make the formulation of scaling theories difficult. Therefore, the development of knowledge related to scale effects, scaling techniques, parameterization and linkages of parameters across scales is highly relevant. The main purpose of this work is to analyse the spatial effect of the static storage capacity parameter H u and the saturated hydraulic conductivity parameter k s from microscale (sub-grid level) to mesoscale (grid level) and its implication to the definition of an optimum cell size. These two parameters describe the upper soil water characteristics in the infiltration process conceptualization of the TETIS hydrological model. At microscale, the spatial heterogeneity of H u and k s was obtained generating random parameter fields through probability distribution functions and a spatial dependence model with pre-established correlation lengths. The effective parameters at mesoscale were calculated by solving the inverse problem for each parameter field. Results indicate that the adopted inverse formulation allows transferring the nonlinearity of the system from microscale to the mesoscale via non-stationary effective parameters. Their values at each cell and time step are in the range of zero to the mean value of the parameter at microscale. The stochastic simulations showed that the variance of the estimated effective parameters decreases when the ratio between mesoscale cell size and correlation length at microscale increases. For a ratio greater than 1, we found cell sizes having the characteristics of a representative elementary area (REA); in such case, the microscale variability pattern did not affect the system response at mesoscale.
11Changes in land use within a catchment are among the causes of non-stationarity in the flood 12 regime, as they modify the upper soil physical structure and its runoff production capacity. This 13 paper analyzes the relation between the variation of the upper soil hydraulic properties due to 14 changes in land use and its effect on the magnitude of peak flows: 1) incorporating fractal scaling 15 properties to relate the effect of the static storage capacity (the sum of capillary water storage 16 capacity in the root zone, canopy interception and surface puddles) and the upper soil vertical 17 saturated hydraulic conductivity on the flood regime; 2) describing the effect of the spatial 18
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