- Title
- Spatial prediction of soil moisture using the Hydrus 1-D model
- Creator
- Chen, M.; Willgoose, G. R.; Saco, P. M.
- Relation
- 32nd Hydrology and Water Resources Symposium (H2009). H2009: Proceedings of H2009, the 32nd Hydrology and Water Resources Symposium (Newcastle, N.S.W. 30 November - 3 December, 2009) p. 920-931
- Relation
- http://www.engineersaustralia.org.au
- Publisher
- Engineers Australia / Causal Productions
- Resource Type
- conference paper
- Date
- 2009
- Description
- This paper investigates the soil moisture dynamics for two subcatchments (Stanley and Krui) in the Goulburn River in NSW during a three year period (2005-2007) using the Hydrus 1-D unsaturated soil water flow model. The model was calibrated on the Stanley microcatchment sites with a single point rainfall record from this microcatchment for both surface 30cm and full profile soil moisture measurement. Soil type, leaf area index and soil depth were found to be the key parameters affecting model performance by shifting the soil moisture time series up and down, changing the steepness of dry-down recessions and driving the lowest point of soil moisture dry-down respectively. Good correlations were obtained between observed and simulated soil water storage (R=0.8~0.9; RMSE=1.8~3.0cm) when calibrated parameters for one site were applied to the other sites. A compromise parameter set that fit all the Stanley sites was obtained by simply altering the soil type slightly. Soil type was also found to be the main determinant (after rainfall) of the mean of modelled soil moisture time series. A consistently observed result was that simulations of topsoil 30cm were better than those of the whole profile soil. Within the Stanley microcatchment excellent soil moisture matches could be generated simply by adjusting the mean of soil moisture up or down slightly. Our observation that soil type drives the mean soil moisture was confirmed by noting that the soil type needed only minor modification from site to site to enable good prediction for all of the sites within Stanley. Both of the adjustment methods (by changing mean, or soil type) turned out to be good, although the correction by the mean showed slightly better statistical results. We extended the predictions of soil moisture to a larger spatial scale using soil and vegetation parameters from Stanley to the sites in the Krui catchment where soil moisture measurement sites were up to 30km distant from Stanley. The results showed promising predictability (R=0.7~0.8; RMSE=1.9~4.5) if considering the different measured rainfall at the sites. These results show that it is possible to use a calibrated soil moisture model to extrapolate the soil moisture to other sites for a catchment with an area of up to 1000km² with homogeneous soil and vegetation. This paper demonstrates the potential usefulness of continuous time, point scale soil moisture data (typical of that measured by permanently installed TDR probes) and simulations for predicting the soil wetness status over a catchment of significant size.
- Subject
- Goulburn River (N.S.W.); Hydrus 1-D unsaturated soil water flow model; rainfall; soil moisture measurement
- Identifier
- uon:8909
- Identifier
- http://hdl.handle.net/1959.13/919547
- Identifier
- ISBN:97808258259461
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