Study area

Southeastern Austrilian has experienced the Millennium drought (1997-2009), which was the worst drought period occurring from 1900 to 2010 (CSIRO, 2012; van Dijk et al., 2013). This drought has caused a severe decrease in agriclutural production and great depletion of water storage. The Wee Jasper catchment has experinced the Millenium drought (Saft et al., 2015), and was chosen as a case study catchment for this study (see Figure 1). It is located in southeastern Austrilia and has an area of 990 km2. The latitude and longitude of the catchment gauging station are 35.17°S and 148.69°E, respectively. This catchment is an unimpaired catchment with almost no human impacts on streamflow, such as reservoirs, land-use changes, irrigation systems,etc . Irrigation has not been reported in this catchment.
[Please insert Figure 1 here]
Climate of the Wee Jasper catchmet is winter-dominated rainfall regime. Mean annual rainfall (P ) of the Wee Jasper catchment is 1002 mm and mean annual potential evapotransipiration (PET) is 1221 mm over the study period. The inter-annual varaibility of P is very large. The coefficient of varaition of annual P during the study period (1970-2014) is about 0.25. The long-term average runoff is 279 mm with a runoff coefficient of 0.28 during the study period. February and March are the driest months with P less than 60 mm/month. July is the wettest month with mean monthly P of 121 mm. However, monthly PET shows an opposite seasonal pattern, which varies from 26 mm in July to 206 mm in January. Therefore, catchment evapotranpiration is generally limited by available water in summer (P < PET), and is limited by available energy in winter (P > PET).
In this study, daily rainfall, potential evaporation, runoff, and other climate variables were collected from the dataset of Zhang et al. (2013). Figure 2 presents the anomalies of rainfall, runoff, and temperature in the Wee Jasper catchment from 1970 to 2014. The Wee Jasper catchment experienced extremely dry conditions during the Millenium drought period (1997-2009). During this period, all years experienced below average rainfall (averaged from 1970 to 2014) except for 1999, 2000, and 2005 when annual rainfall was slightly above the long-term mean. All years from 1997 to 2009 experienced below average annual runoff except 2000. All years from 1997 to 2009 had above average annual temperature.
[Please insert Figure 2 here]