The Combined Drought Indicator is one source of information that informs policy and Government responses to changing seasonal conditions, including drought. The map provides a snapshot of conditions at a point in time and is not used to determine eligibility for drought assistance measures offered by the NSW Government.
Much of the information in the Seasonal Conditions Report is sourced from the NSW DPI Enhanced Drought Information System (EDIS)™. EDIS is currently available in prototype form and is subject to an intensive ground truthing process. For more information, visit the interactive website via droughthub.nsw.gov.au.
EDIS is an ongoing project aimed at improving the quality and timeliness of efforts to monitor conditions across the state. Key features of the system are:
The way in which the indicators are combined to form the CDI is described in Table 1 below.
Description of the Combined Drought Indicator framework
CDI Phase | Technical definition | Description - typical field conditions |
---|---|---|
Non-drought | All indicators greater than the 50th percentile or all indicators are greater than the 30th percentile AND the previous category is Non-drought | Production is not limited by climatic conditions. |
Recovering | All indicators are greater than the 30th percentile AND any indicator is less than the 50th percentile AND the previous category is Drought Affected. | Production is occurring but would be considered ‘below average’. Full production recovery may not have occurred if this area has experienced drought conditions over the past six months. |
Drought Affected (weakening) | Any indicator is less than the 30th percentile AND Positive 5-month Rainfall Index trend (DDI>0.4). | Production conditions are getting tighter, but there have been some falls of rain over the past month. It is rare to enter the Recovering phase from the Non-Drought category; Usually there is a quick (1-2 week) transition into Drought Affected or Drought. When indicators are close to the Drought threshold drought conditions are severe. |
Drought Affected (intensifying) | Any indicator is less than the 30th percentile AND Negative 5-month Rainfall Index trend (DDI≤0.4). | Conditions are deteriorating; production is beginning to get tighter. Ground cover may be modest, but growth is moderate to low for the time of year. When indicators are close to the Drought threshold drought conditions are severe. |
Drought | Any indicator is less than the 5th percentile | Conditions may be very dry, or agronomic production is tight (low soil moisture or plant growth). It is possible to be in Drought when there has been some modest growth, or a few falls of rain. |
Intense Drought | All three indicators (rainfall, soil water, plant growth) are below the 5th percentile | Ground cover is very low, soil moisture stores are exhausted, and rainfall has been minimal over the past 6-12 months. |