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]