Earth Observation
GIEWS
The country level maps and graphs depict the latest 36-month period of the seasonal, vegetation and precipitation indicators. The data is presented by dekad and month.   More
All three vegetation indicators are based on 10-day (dekadal) vegetation data from the METOP-AVHRR sensor at 1 km resolution (2007 and after). Data at 1 km resolution for the period 1984-2006 are derived from the NOAA-AVHRR dataset at 16 km resolution. Precipitation estimates for all African countries (except Cabo Verde and Mauritius) are taken from NOAA/FEWSNet, while for the remaining countries data is obtained from ECMWF.
DISCLAIMERS
The designations employed and the presentation of material in the maps do not imply the expression of any opinion whatsoever on the part of FAO concerning the legal or constitutional status of any country, territory or sea area, or concerning the delimitation of frontiers.
Nigeria
 

Agricultural Stress Index  More
The Agricultural Stress Index (ASI) is a quick-look indicator that facilitates the early identification of cropped land with a high likelihood of water stress (drought). The Index is based on the integration of the Vegetation Health Index (VHI) in two dimensions that are critical in the assessment of a drought event in agriculture: temporal and spatial. The first step of the ASI calculation is a temporal averaging of the VHI, assessing the intensity and duration of dry periods occurring during the crop cycle at the pixel level; this calculation includes the use of crop coefficients, which introduces sensitivity of a crop to water stress during each phenological phase. The second step determines the spatial extent of drought events by calculating the percentage of pixels in arable areas with a VHI value below 35 percent (this value was identified as a critical threshold in assessing the extent of drought in previous research by Kogan, 1995). Each administrative area is classified according to the percentage of the affected area to facilitate the quick interpretation of results.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Drought Intensity  More
Agricultural droughts are classified by their intensity and are categorized into four classes: Extreme, Severe, Moderate or Mild. The intensity of the drought is calculated through the Weighted Mean Vegetation Health Index aggregated per GAUL 2 region, indicating that the poorer the vegetation health the more severe the drought.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Mean Vegetation Health Index  More
The Mean Vegetation Health Index (Mean VHI) allows the user to assess the severity of the drought from the start of the growing season, examining the vegetation health and the influence of temperature on plant conditions. The Mean VHI is an average of the dekadal VHI values over the crop-growing season to date. It takes into account the sensitivity of a crop to water stress over its growing season and calculates the temporal impact of moisture deficits since the start of the growing season until the current dekad.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Agricultural Stress Index  More
The Agricultural Stress Index (ASI) is a quick-look indicator that facilitates the early identification of cropped land with a high likelihood of water stress (drought). The Index is based on the integration of the Vegetation Health Index (VHI) in two dimensions that are critical in the assessment of a drought event in agriculture: temporal and spatial. The first step of the ASI calculation is a temporal averaging of the VHI, assessing the intensity and duration of dry periods occurring during the crop cycle at the pixel level; this calculation includes the use of crop coefficients, which introduces sensitivity of a crop to water stress during each phenological phase. The second step determines the spatial extent of drought events by calculating the percentage of pixels in arable areas with a VHI value below 35 percent (this value was identified as a critical threshold in assessing the extent of drought in previous research by Kogan, 1995). Each administrative area is classified according to the percentage of the affected area to facilitate the quick interpretation of results.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Drought Intensity  More
Agricultural droughts are classified by their intensity and are categorized into four classes: Extreme, Severe, Moderate or Mild. The intensity of the drought is calculated through the Weighted Mean Vegetation Health Index aggregated per GAUL 2 region, indicating that the poorer the vegetation health the more severe the drought.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Mean Vegetation Health Index  More
Agricultural droughts are classified by their intensity and are categorized into four classes: Extreme, Severe, Moderate or Mild. The intensity of the drought is calculated through the Weighted Mean Vegetation Health Index aggregated per GAUL 2 region, indicating that the poorer the vegetation health the more severe the drought.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Agricultural Stress Index  More
The Annual ASI depicts the percentage of arable land, within an administrative area, that has been affected by drought conditions over the entire cropping season. It differs from ASI, which is based on conditions from the start of the season up to the current dekad.
 
2017 2016 2015
2014 2013 2012
2011 2010 2009
2008 2007 2006
2005 2004 2003
2002 2001 2000
1999 1998 1997
1996 1995 1994
1993 1992 1991
1990 1989 1988
1987 1986 1985
 
1984

Drought Intensity  More
Agricultural droughts are classified by their intensity and are categorized into four classes: Extreme, Severe, Moderate or Mild. The intensity of drought is calculated through the Weighted Mean Vegetation Health Index, indicating that the poorer the vegetation health the more severe the drought. The Annual summary of Drought Intensity allows the user to assess the overall intensity of drought for an entire growing season.
2017 2016 2015
2014 2013 2012
2011 2010 2009
2008 2007 2006
2005 2004 2003
2002 2001 2000
1999 1998 1997
1996 1995 1994
1993 1992 1991
1990 1989 1988
1987 1986 1985
 
1984

Mean Vegetation Health Index  More
The Annual Mean Vegetation Health Index (Mean VHI) allows the user to assess the overall severity of drought for an entire growing season, examining the vegetation health and the influence of temperature on plant conditions. The Annual Mean VHI takes into account the sensitivity of a crop to water stress over its growing season, and calculates the temporal impact of moisture deficits and temperature over the complete growing season.
 
2017 2016 2015
2014 2013 2012
2011 2010 2009
2008 2007 2006
2005 2004 2003
2002 2001 2000
1999 1998 1997
1996 1995 1994
1993 1992 1991
1990 1989 1988
1987 1986 1985
 
1984

Agricultural Stress Index  More
The Annual ASI depicts the percentage of arable land, within an administrative area, that has been affected by drought conditions over the entire cropping season. It differs from ASI, which is based on conditions from the start of the season up to the current dekad.
 
2017 2016 2015
2014 2013 2012
2011 2010 2009
2008 2007 2006
2005 2004 2003
2002 2001 2000
1999 1998 1997
1996 1995 1994
1993 1992 1991
1990 1989 1988
1987 1986 1985
 
1984

Drought Intensity  More
Agricultural droughts are classified by their intensity and are categorized into four classes: Extreme, Severe, Moderate or Mild. The intensity of drought is calculated through the Weighted Mean Vegetation Health Index, indicating that the poorer the vegetation health the more severe the drought. The Annual summary of Drought Intensity allows the user to assess the overall intensity of drought for an entire growing season.
2017 2016 2015
2014 2013 2012
2011 2010 2009
2008 2007 2006
2005 2004 2003
2002 2001 2000
1999 1998 1997
1996 1995 1994
1993 1992 1991
1990 1989 1988
1987 1986 1985
 
1984

Mean Vegetation Health Index  More
The Annual Mean Vegetation Health Index (Mean VHI) allows the user to assess the overall severity of drought for an entire growing season, examining the vegetation health and the influence of temperature on plant conditions. The Annual Mean VHI takes into account the sensitivity of a crop to water stress over its growing season, and calculates the temporal impact of moisture deficits and temperature over the complete growing season.
 
2017 2016 2015
2014 2013 2012
2011 2010 2009
2008 2007 2006
2005 2004 2003
2002 2001 2000
1999 1998 1997
1996 1995 1994
1993 1992 1991
1990 1989 1988
1987 1986 1985
 
1984

Historic Drought Frequency   More
The maps depict the frequency of severe drought in areas where: i) 30 percent of the cropped land; or ii) 50 percent of the cropped land has been affected. The historical frequency of severe droughts (as defined by ASI) is based on the entire the times series (1984-2017).
>30% of the cropland affected


>50% of the cropland affected



Historic Drought Frequency   More
The maps depict the frequency of severe drought in areas where: i) 30 percent of the cropped land; or ii) 50 percent of the cropped land has been affected. The historical frequency of severe droughts (as defined by ASI) is based on the entire the times series (1984-2017).
>30% of the cropland affected


>50% of the cropland affected




The seasons’ progress is based on the long-term average of vegetation phenology for each pixel. This simplification implies that the crop/pasture phenology is static and therefore the growing seasons progress at a constant rate each year.
Start of Season (SOS) indicates the period of a crop/grass’s emergence, and is defined as the point when the NDVI reaches 25 percent of its maximum value.


Maximum of Season (MOS) indicates the period when the crop/grass’s foliage is fully developed, prior to the harvest period. It is calculated as the point when the NDVI is at its maximum value.


End of Season (EOS) indicates when the crop/grass has reached full maturity, and is defined as the point when the NDVI is at 75 percent for crop and 25 percent for grass of its maximum value (MOS).




The seasons’ progress is based on the long-term average of vegetation phenology for each pixel. This simplification implies that the crop/pasture phenology is static and therefore the growing seasons progress at a constant rate each year.
Start of Season (SOS) indicates the period of a crop/grass’s emergence, and is defined as the point when the NDVI reaches 25 percent of its maximum value.


Maximum of Season (MOS) indicates the period when the crop/grass’s foliage is fully developed, prior to the harvest period. It is calculated as the point when the NDVI is at its maximum value.


End of Season (EOS) indicates when the crop/grass has reached full maturity, and is defined as the point when the NDVI is at 75 percent for crop and 25 percent for grass of its maximum value (MOS).



Agricultural Stress Index  More
The Agricultural Stress Index (ASI) is a quick-look indicator that facilitates the early identification of cropped land with a high likelihood of water stress (drought). The Index is based on the integration of the Vegetation Health Index (VHI) in two dimensions that are critical in the assessment of a drought event in agriculture: temporal and spatial. The first step of the ASI calculation is a temporal averaging of the VHI, assessing the intensity and duration of dry periods occurring during the crop cycle at the pixel level; this calculation includes the use of crop coefficients, which introduces sensitivity of a crop to water stress during each phenological phase. The second step determines the spatial extent of drought events by calculating the percentage of pixels in arable areas with a VHI value below 35 percent (this value was identified as a critical threshold in assessing the extent of drought in previous research by Kogan, 1995). Each administrative area is classified according to the percentage of the affected area to facilitate the quick interpretation of results.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Drought Intensity  More
Agricultural droughts are classified by their intensity and are categorized into four classes: Extreme, Severe, Moderate or Mild. The intensity of the drought is calculated through the Weighted Mean Vegetation Health Index aggregated per GAUL 2 region, indicating that the poorer the vegetation health the more severe the drought.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Mean Vegetation Health Index  More
The Mean Vegetation Health Index (Mean VHI) allows the user to assess the severity of the drought from the start of the growing season, examining the vegetation health and the influence of temperature on plant conditions. The Mean VHI is an average of the dekadal VHI values over the crop-growing season to date. It takes into account the sensitivity of a crop to water stress over its growing season and calculates the temporal impact of moisture deficits since the start of the growing season until the current dekad.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Agricultural Stress Index  More
The Agricultural Stress Index (ASI) is a quick-look indicator that facilitates the early identification of cropped land with a high likelihood of water stress (drought). The Index is based on the integration of the Vegetation Health Index (VHI) in two dimensions that are critical in the assessment of a drought event in agriculture: temporal and spatial. The first step of the ASI calculation is a temporal averaging of the VHI, assessing the intensity and duration of dry periods occurring during the crop cycle at the pixel level; this calculation includes the use of crop coefficients, which introduces sensitivity of a crop to water stress during each phenological phase. The second step determines the spatial extent of drought events by calculating the percentage of pixels in arable areas with a VHI value below 35 percent (this value was identified as a critical threshold in assessing the extent of drought in previous research by Kogan, 1995). Each administrative area is classified according to the percentage of the affected area to facilitate the quick interpretation of results.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Drought Intensity  More
Agricultural droughts are classified by their intensity and are categorized into four classes: Extreme, Severe, Moderate or Mild. The intensity of the drought is calculated through the Weighted Mean Vegetation Health Index aggregated per GAUL 2 region, indicating that the poorer the vegetation health the more severe the drought.
  First DekadSecond DekadThird Dekad
  
    
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Mean Vegetation Health Index  More
The Mean Vegetation Health Index (Mean VHI) allows the user to assess the severity of the drought from the start of the growing season, examining the vegetation health and the influence of temperature on plant conditions. The Mean VHI is an average of the dekadal VHI values over the crop-growing season to date. It takes into account the sensitivity of a crop to water stress over its growing season and calculates the temporal impact of moisture deficits since the start of the growing season until the current dekad.
  First DekadSecond DekadThird Dekad