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variability of droughts in the area of study. The PCA allows us to find regions with
a similar occurrence of droughts detected by SPI-12 time series (Fig. 8.6).
Considering the analysis in the previous section, the spatial distribution as principal
component 1 (RPC1) indicates a high positive loading along the northern part of the
state. In this area, droughts are more frequent. The second component (RPC2) indicates regions where drought events are also frequent but at a lower extent than in the
area reported in the first component. The third (RPC3) shows an area where the
drought events are less frequent. Although three RPCs were unable to extract the
total variation of drought across the region, this operation was successful in finding
the three major kinds of drought variabilities present in the area of study.
Conclusions
This study effectively identified the spatial and temporal variations and trends in
rainfall and drought after 35 years of data in a semi-arid region of Northern Mexico.
In much of the state of Durango, 70% or more of the annual rainfall occurs in July,
Fig. 8.6 Spatial variability of the loading for three rotated principal components obtained for the
analysis of drought time series by SPI12
8 Spatial and Temporal Analysis of Precipitation and Drought Trends Using…
variability of droughts in the area of study. The PCA allows us to find regions with
a similar occurrence of droughts detected by SPI-12 time series (Fig. 8.6).
Considering the analysis in the previous section, the spatial distribution as principal
component 1 (RPC1) indicates a high positive loading along the northern part of the
state. In this area, droughts are more frequent. The second component (RPC2) indicates regions where drought events are also frequent but at a lower extent than in the
area reported in the first component. The third (RPC3) shows an area where the
drought events are less frequent. Although three RPCs were unable to extract the
total variation of drought across the region, this operation was successful in finding
the three major kinds of drought variabilities present in the area of study.
Conclusions
This study effectively identified the spatial and temporal variations and trends in
rainfall and drought after 35 years of data in a semi-arid region of Northern Mexico.
In much of the state of Durango, 70% or more of the annual rainfall occurs in July,
Fig. 8.6 Spatial variability of the loading for three rotated principal components obtained for the
analysis of drought time series by SPI12
8 Spatial and Temporal Analysis of Precipitation and Drought Trends Using…