Few ensemble streamflow forecasting systems are designed to operate for ephemeral rivers. In this study, we revise our error model for generating Forecast Guided Stochastic Scenarios (FoGSS) to produce statistically reliable long-range (12-month) forecasts for ephemeral rivers. FoGSS features an error model with four stages: data transformation, bias-correction, an autoregressive error model and the statistical distribution of residuals. We revise the fourth stage of FoGSS with a parameter estimation method that uses data censoring to account for zero values in both observations and forecasts. This allows FoGSS to produce statistically reliable ensemble forecasts in even highly ephemeral streams (with >50% zero flows). We apply FoGSS to conventional ensemble hydrological prediction (ESP) forecasts for 50 Australian catchments, including 26 ephemeral rivers. We show that FoGSS improves the accuracy of ESP forecasts at short lead times, while at long lead times FoGSS forecasts transition to climatology-like forecasts. FoGSS forecasts are reliable in ensemble spread at individual lead times and for volumes aggregated over lead times, even in highly ephemeral rivers. FoGSS forecasts pave the way for operational long-range forecasts in ephemeral rivers, meeting a key need for improved water management.

Item Type:	Refereed Article
Keywords:	ephemeral rivers, dryland streams, long-range forecasting, ESP, FoGSS, ensemble prediction
Research Division:	Earth Sciences
Research Group:	Hydrology
Research Field:	Surface water hydrology
Objective Division:	Environmental Policy, Climate Change and Natural Hazards
Objective Group:	Environmental policy, legislation and standards
Objective Field:	Water policy (incl. water allocation)
UTAS Author:	Bennett, JC (Mr James Bennett)
UTAS Author:	Michael, K (Dr Kelvin Michael)
ID Code:	148266
Year Published:	2021
Deposited By:	CRC-Antarctic Climate & Ecosystems
Deposited On:	2021-12-15
Last Modified:	2022-01-17
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