Frequently Asked Questions

Datasets

How is the Combined Drought Indicator computed?

Combined Drought Indicator based on SPI (from CHIRPS), soil moisture and fAPAR, to identify areas with potential to suffer agricultural drought, areas where the vegetation is already affected by drought conditions, and areas in recovery process to normal conditions after a drought episode. The method is based in 5 impact levels.

These levels are:

‘Watch’ when a relevant precipitation shortage is observed,
‘Warning’ when this precipitation shortage comes with a soil moisture anomaly,
‘Alert’ when these two conditions are accompanied with an anomaly in the vegetation condition,
‘Partial recovery’ when after a drought episode, the meteorological conditions are recovered to normal but not the vegetation conditions,
‘Full recovery’ when meteorological and vegetation normal conditions are recovered.

When will the next CDI be generated?

CDI is computed based on availability of SPI, fAPAR Anomaly and Soil Moisture Anomaly data as shown in the table below.

CDI (dekad)

fAPAR Anomaly (dekad)

SMA (dekad)

SPI (month)

1st

1st (same month

as CDI)

3rd (previous month

from CDI)

previous month

from CDI

2nd

2nd (same month

as CDI)

1st (same month

as CDI)

previous month

from CDI

3rd

3rd (same month

as CDI)

2nd (same month

as CDI)

same month

as CDI

To elaborate the above table better, below is an example of computation of dekadal CDI for the month of November.

CDI (dekad)	fAPAR Anomaly (dekad)	SMA (dekad)	SPI (month)
1st Dekad November	1st Dekad November	3rd Dekad October	October
2nd Dekad November	2nd Dekad November	1st Dekad November	October
3rd Dekad November	3rd Dekad November	2nd Dekad November	November

Availability of fAPAR Anomaly and Soil Moisture Anomaly datasets is approximately during the dates shown below.

Month	Dekad	Data availability dates (these are the dates when fAPAR Anomaly and Soil Moisture will be made available on JRC Jeodpp)
Month	Dekad	FAPAR Anomaly	Soil Moisture Anomaly
January	1st	18th January	21st January
	2nd	26th January	1st February
	3rd	3rd February	11th February
February	1st	19th February	21st February
	2nd	27th February	1st March
	3rd	7th March	11th March
March	1st	15th March	21st March
	2nd	23rd March	1st April
	3rd	8th April	11th April
April	1st	16th April	21st April
	2nd	24th April	1st May
	3rd	2nd May	11th May
May	1st	18th May	21st May
	2nd	26th May	1st June
	3rd	3rd June	11th June
June	1st	19th June	21st June
	2nd	27th June	1st July
	3rd	5th July	11th July
July	1st	13th July	21st July
	2nd	29th July	1st August
	3rd	6th August	11th August
August	1st	14th August	21st August
	2nd	22nd August	1st September
	3rd	7th September	11th September
September	1st	15th September	21st September
	2nd	23rd September	1st October
	3rd	9th October	11th October
October	1st	17th October	21st October
	2nd	25th October	1st November
	3rd	2nd November	11th November
November	1st	18th November	21st November
	2nd	26th November	1st December
	3rd	4th December	11th December
December	1st	12th December	21st December
	2nd	28th December	1st January
	3rd	5th January	11th January

Is there an option to download raster data on the drought watch?

Both Geotiff and NetCDF Raster files for datasets on the mapviewer are available on drought watch’s https file server at https://droughtwatch.icpac.net/ftp . All files are grouped yearly and bands/time dimansions split based on the temporal resolution.

What is the rationale for having recovery levels on the CDI?

Recovery levels on the CDI highlight areas that have returned to their normal conditions after experiencing drought. Partial Recovery areas capture areas that have recovered to their normal meteorological conditions but not vegetation growth while Full Recovery areas have recovered to their normal meteorological and agricultural conditions.

Why is the Combined Drought Indicator saying an area is experiencing drought when I know it is not?

Generally the assessment of drought is done using individual indicators that are based on meteorological or hydrological data, or remote sensing imagery. The development of a combined indicator that integrates meteorological, hydrological and remote sensing data, can help to reduce false alarms, which may arise for example in the case of vegetation-based indicators (e.g. FAPAR Anomaly) where a biomass reduction can be caused by factors other than a drought-induced water stress.

The final output should be interpreted as showing areas potentially experiencing drought. Several factors could lead to the identification of patterns of drought occurence which do not seem to correlate to what is happening on the ground, the date of analysis being a very important one. While the Combined Drought Indicator integrates Soil Moisture Anomaly, SPI and fAPAR Anomaly data to yield its results, it is yet to integrate exposure/vulnerability information to furthur customize it for the region. It is also worth noting the accuracy of the CDI is constrained by the accuracy of the datasets it is derived from.

Plans are underway to develop a form to crowdsource ground truth information relating to the occurence of drought. In the meantime, feel free to drop your feedback at https://droughtwatch.icpac.net/contact/

Future Plans

Any plans on predicting drought?

Plans are underway to incorporate forecasted datasets relevant to drought e.g Forecasted SPI.

Do you plan to support raster data download for custom areas of interest?

In addition to supplying raster data for the entire region, development plans are underway to allow users to dynamically download raster files on the system for a subset of their area of interest.

Plans for analysis at lower admin levels?

Currently, the system allows for analysis at Administrative Level 1. Development is well underway to extend this analysis for lower administrative levels.

Any other future plans?

The development of the system is currently ongoing with plans to integrate periodic products disseminated as comprehensive reports to subscribed users, provide additional thematic datasets, perform drought forecasting, translate system warnings into impact-based information/warnings among other plans.