Rainfall-runoff modelling in South-west Western Australia. 3. Performance of the 'adopted model'. South-west Western Australia Sustainable Yields Project: Technical Report. A report to the Australian Government from the CSIRO South-West Western Australia Sustainable Yields Project

[摘要] 106 gauged catchments were used in model calibration using streamflow data from within the period 1975 to 2007.The calibrated catchments comprise 67 percent of the area of the surface water basins in the project area, are distributed well over the surface water modelling area, and account for a little more than 67 percent of the total flow. Although observed rainfall and simulated areal potential evaporation (APET) data were available for the full 33 years, the streamflow data length ranged from 10 years upwards.Mean annual runoff in the calibration catchments ranged from 5 to 348 mm, with a median value of 112 mm.Five rainfall–runoff models were calibrated for the gauged catchments. Calibration results from weighted means of all 31 linear additive combinations of the five models were examined for their ability to reproduce the measured streamflows. The mean of the daily runoff from the Sacramento and IHACRES models consistently resulted in a better model fit than any other combination of the individual models and this ‘adopted model’ was used for scenario modelling. For both the selected models values of several of the optimised parameters occurred at or very close to one or other of the allowed range boundaries of the parameters, suggesting that the optimiser range may have been too constrictive to allow a global optimum to be reached. This suggests a limitation of the implementation of the optimisers that could be improved in future developments.In about half the calibration catchments the models over estimate runoff in the last 5 to 10 years of record, and under estimate in the first 10 years of the record. Our interpretation of this is that it is due to the changing groundwater status in these catchments resulting from the recent drying climate not being well represented in the current models. However, it could also be due to increasing vegetation cover in catchments subject to large scale plantation development in the last decade, or to changes in rainfall characteristics and seasonal distribution not adequately represented in the previous decades. Whatever the cause, the implication is that our modelling may over estimate projected streamflows.

[发布日期] 2010-12-31 [发布机构] CSIRO

[效力级别] Earth Sciences not elsewhere classified [学科分类] 地球科学(综合)