TY - JOUR
T1 - On the validation of a coupled water and energy balance model at small catchment scales
AU - Silberstein, R. P.
AU - Sivapalan, M.
AU - Wyllie, A.
N1 - Funding Information:
Thanks are expressed to the officers of the Water Authority of Western Australia, Surface Water Branch, for data from the Salmon and Wights paired catchment study and the nearby climate station used in calibrating and validating the water balance and coupled models. The officers of the Department of Agriculture of Western Australia, particularly Ian Foster, provided climatic data, and Joe Kinal, of the Department of Conservation and Land Management, provided soil temperature data used to test the energy balance submodel. Dr Richard Smith, of the Leeuwin Centre for Remote Sensing, is particularly thanked for his participation in helpful discussions. Thanks are also due to Ross Woods and John Snell for many helpful comments during preparation of this manuscript, and to two anonymous reviewers whose comments led to a discovery of errors in the original data processing and resulted in significantly reduced offset in the correlation between the Landsat data and the modelled surface temperatures. This research was supported in part by a special Environmental Fluid Dynamics grant of the University of Western Australia, and a grant from the Australian Research Council, both awarded to the second author. R.P. Silberstein was supported by a University of Western Australia Research Scholarship, and a Centre for Water Research Scholarship. CWR Ref. ED 927 RS.
PY - 1999/9/9
Y1 - 1999/9/9
N2 - Catchment runoff is the most widely used catchment scale measurement in modelling studies, and we have a reasonable degree of confidence in its accuracy. The advent of satellites gives access to a new suite of measurements taken over a defined spatial range. These measurements, principally reflected or emitted radiation, provide hydrologists with new possibilities for quantifying the state of a catchment. Surface temperatures can be readily measured by a satellite on a scale comparable to the size of a small catchment. In this paper we show that satellite sensed temperatures can provide an important measure of catchment status, which can complement runoff measurements in water balance studies. A one-dimensional model, which couples the land surface energy balance with the soil and surface water balance is tested by comparison with runoff and with remotely sensed surface temperature measurements. Simulations have been run over four years for two small catchments which have a fairly homogeneous vegetation, one being forest and its neighbour pasture. Satellite 'surface' temperatures have been interpreted in terms of the energy balance, and used as a test of modelling accuracy. An 'effective' surface temperature is calculated as a weighted mean of temperatures of the separate soil and leaf surfaces. This modelled 'effective' temperature correlates well with Landsat TM surface temperatures. When pasture replaces forest, the model predicts a reduction in evapotranspiration of around 30%, a three-fold increase in runoff, and an increase in mean soil moisture status. The change to pasture also results in a rise in mean effective surface temperature of about 4°C, and an increase in summer diurnal temperature range from 10 to 22°C. The winter diurnal temperature range is similar for both vegetation systems. Inclusion of soil moisture variability in thermal properties results in an increase in mean daily maximum temperature of about 2°C in summer and winter, without much change in daily minima. The daily mean temperature is not significantly affected.
AB - Catchment runoff is the most widely used catchment scale measurement in modelling studies, and we have a reasonable degree of confidence in its accuracy. The advent of satellites gives access to a new suite of measurements taken over a defined spatial range. These measurements, principally reflected or emitted radiation, provide hydrologists with new possibilities for quantifying the state of a catchment. Surface temperatures can be readily measured by a satellite on a scale comparable to the size of a small catchment. In this paper we show that satellite sensed temperatures can provide an important measure of catchment status, which can complement runoff measurements in water balance studies. A one-dimensional model, which couples the land surface energy balance with the soil and surface water balance is tested by comparison with runoff and with remotely sensed surface temperature measurements. Simulations have been run over four years for two small catchments which have a fairly homogeneous vegetation, one being forest and its neighbour pasture. Satellite 'surface' temperatures have been interpreted in terms of the energy balance, and used as a test of modelling accuracy. An 'effective' surface temperature is calculated as a weighted mean of temperatures of the separate soil and leaf surfaces. This modelled 'effective' temperature correlates well with Landsat TM surface temperatures. When pasture replaces forest, the model predicts a reduction in evapotranspiration of around 30%, a three-fold increase in runoff, and an increase in mean soil moisture status. The change to pasture also results in a rise in mean effective surface temperature of about 4°C, and an increase in summer diurnal temperature range from 10 to 22°C. The winter diurnal temperature range is similar for both vegetation systems. Inclusion of soil moisture variability in thermal properties results in an increase in mean daily maximum temperature of about 2°C in summer and winter, without much change in daily minima. The daily mean temperature is not significantly affected.
KW - Catchments
KW - Energy
KW - Modelling
KW - Remote sensing
KW - Water balance
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U2 - 10.1016/S0022-1694(99)00075-X
DO - 10.1016/S0022-1694(99)00075-X
M3 - Article
AN - SCOPUS:0344117624
SN - 0022-1694
VL - 220
SP - 149
EP - 168
JO - Journal of Hydrology
JF - Journal of Hydrology
IS - 3-4
ER -