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Corresponde a la presentación realizada por Francisco Zambrano Bigiarini en el primer seminario internacional: “Gestión y monitoreo de la variabilidad climática y el uso eficiente del recurso hídrico en la región semiárida de Coquimbo”, organizado por el Centro de Estudios Avanzados en Zonas Aridas (CEAZA), efecutuado los dias 26 y 27 de noviembre del 2012
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Drought index based on remote sensing, using ’R’ and’raster’ package, in B́ıo-B́ıo region, Chile.
Francisco Zambrano Bigiarini
INIA
7 de diciembre de 2012
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 1 / 35
Outline
1 General Review
2 Vegetation Condition Index (VCI)
3 Preliminary Results
4 Recommendations
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 2 / 35
General Review
Drought and its Classification
DefinitionThere is not a precise definition of drought
• ’drought means a sustained, extended deficiency in precipitation’ (WMO,1986)
• ’the percentage of years when crops fail from the lack of moisture’ (FAO, 1983)
• .....
Depending on the field/context, a drought event can be
1 Meteorological: drought is usually based on long-term precipitation departures fromnormal.
2 Hydrological: drought refers to deficiencies in surface and subsurface water supplies.
3 Agricultural: drought occurs when there is insufficient soil moisture to meet the needs of aparticular crop at a particular time.
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 4 / 35
General Review
Why use remote sensing for drought assessment?
Advantages
• Local and global monitoring.
• Spatial and temporal assesment.
• Widly used in the last two decades for monitoring vegetationcondition.
• A good choice for a developing country, which have insufficientdensity of weather stations
• Since 2000 we have data with highly temporal resolution and mediumspatial resolution from sensor MODIS.
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 5 / 35
General Review
Normalized Difference Vegetation Index (NDVI)
In short
It is a measure of the vegetation health.
NDV I =NIR− V IS
NIR+ V IS(1)
−1 ≤ NDV I ≤ 1
But in agricultural, its value is abovezero.
0 − > poor vegetation condition.1 − > good vegetation condition
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 6 / 35
General Review
Informatic tools for remote sensing and GIS
Wide variety of softwares
• Propietary (Very high cost applications): ENVI, ERDAS, ESRI, Matlab
• OpenSource: GRASS GIS, QGIS, ILWISS, R
What is needed?
• Procesing a huge amount of data raster.
• Perform sophisticated data analysis and graphics.
• Interact with other software.
• Work efficiently
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 7 / 35
Vegetation Condition Index (VCI)
VCI features (Kogan,1994)
• Derived from the NDVI
• Was designed to separate the weather related component of NDVIfrom ecological factors.
• Reflects the spatial and temporal vegetation variability.
• Its a scaling of the NDVI between its maximum and minimum.
• Has excellent ability to detect drought and to mesure time of itsonset, intensity, duration, and impact on vegetation.
• Its value goes between 0 and 100 %
V CIi = 100NDV Ii −NDV Imin
NDV Imax −NDV Imin(2)
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 9 / 35
Vegetation Condition Index (VCI)
Calculation example for a single pixel
1 We use data from MODIS sensor (2000-2012), 16 days composite.
2 Firstly we need an smoothed NDVI. (LOWESS (Cleveland,1981))
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 10 / 35
Vegetation Condition Index (VCI)
Calculation example for a single pixel
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 11 / 35
Vegetation Condition Index (VCI)
Calculation example for a single pixel
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 12 / 35
Vegetation Condition Index (VCI)
NDVI and VCI, 2000-2012
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 13 / 35
Preliminary Results
Whole region
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 15 / 35
Preliminary Results
Whole region
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 16 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 17 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 18 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 19 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 20 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 21 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 22 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 23 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 24 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 25 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 26 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 27 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 28 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 29 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 30 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 31 / 35
Preliminary Results
Spatial and temporal evolution in a drought season
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 32 / 35
Recommendations
Recommendations
• Analysis in the agricultural area (LANDCOVER).
• Consider the period most sensitive for crop growth.
• Validation of the VCI, make regression analysis with some variables.(crop yield, biomass, rainfall,...)
• Make research in the sense to extend the time series of NDVI images(NOAA, AVHHR).
• Sophisticated time series analysis.
• Extend the analysis to whole country.
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 34 / 35
Recommendations
Thanks?Questions?
[email protected] (INIA) Drought index based en RS using R 7 de diciembre de 2012 35 / 35