Regional-scale hydrological modelling using multiple-parameter landscape zones and a quasi-distributed water balance model

Abstract

Regional-scale catchments are characterised typically by natural variability in climatic and land-surface features. This paper addresses the important question regarding the appropriate level of spatial disaggregation necessary to guarantee a hydrologically sound consideration of this variability. Using a simple hydrologic model along with physical catchment data, the problem is reconsidered as a model parameter identification problem. With this manner of thinking the subjective nature as to what to include in the disaggregation scheme is removed and the problem reconsidered in terms of what can be supported by the available data. With such an approach the relative merit of different catchment disaggregation schemes is viewed in terms of their ability to provide constrained parameterisations that can be explained in terms of the physical processes deemed active within a catchment. The outlined methodology was tested for a regional-scale catchment, located in eastern Australia, and involved using the quasi-distributed VIC catchment model to recover the characteristic responses resulting from the disaggregation of the catchment into combinations of climate, soil and vegetation characteristics. A land-surface classification based on a combination of soil depth and land cover type was found to provide the most accurate streamflow predictions during a 10-year validation period. Investigation of the uncertainty associated with the predictions due to weakly identified parameters however, revealed that a simpler classification based solely on land cover actually provided a more robust parameterisation of streamflow response. The result alludes to the hydrological importance of distinguishing between forested and non-forested land cover types at the regional-scale, and suggests that given additional information soil-depth / storage considerations may also have proved significant. Improvements to the outlined method are discussed in terms of increasing the informative content available to differentiate between competing catchment responses.

Analysis of the spatial variation in the parameters of the SWAT model with application in Flanders, Northern Belgium

“…In their study, the spatially-distributed parameterisation obtained by a multisite calibration leads to a better model fit than the singlesite calibration, treating model parameters as spatially invariant. Wooldridge and Kalma (2001) draw a similar conclusion for the comparison of a lumped and a semidistributed parameterisation of the conceptual VIC model structure: the semi-distributed parameterisation results in a better model performance. In general, for large-scale applications of a hydrological model, insight into the spatial variation in parameter optima can improve the performance of a model.…”

Representation of landscape variability and lateral redistribution processes for large-scale hydrological modelling in semi-arid areas

“…In most cases, the discretization of the landscape is done with regard to similarity of vertical hydrological processes, i.e. hydrotopes being similar in terms of infiltration, percolation and evapotranspiration fluxes (Kite and Kouwen, 1992;Krysanova et al, 1998;Becker and Braun, 1999;Gurtz et al, 1999;Wooldridge and Kalma, 2001). This is usually achieved by intersecting physiographic data such as elevation, soils, vegetation and land use.…”

“…Secondly, they lie in the selection of those landscape characteristics, heterogeneities and related hydrological processes that ensure that the assumption of similarity of the hydrological response within one of the accordingly delineated modelling units is valid. This selection can be based on expert knowledge, the perception of the hydrological behaviour of the study area and on comparative studies, which evaluate the performance of models for different ways of delineating the hydrotopes (Becker and Braun, 1999;Wooldridge and Kalma, 2001). In most cases, the discretization of the landscape is done with regard to similarity of vertical hydrological processes, i.e.…”

Investigation of the Relationship between Groundwater Level Fluctuation and Vegetation Cover by using NDVI for Shaqlawa Basin, Kurdistan Region – Iraq

“…The change of depth to groundwater is related to atmospheric and surface conditions, such as precipitation, temperature, soil adoption, vegetation water content, soil humidity and evaporation (Liang et al, 1994;Mitchell & DeWalle, 1998;Wooldridge & Kalma, 2001). Groundwater fluctuation analysis estimated the variations in stored water, renewable storage water quantity, and the investment of groundwater (Lioyd, 1999).…”