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Assessment of Meteorological Drought Hazard Area using GIS in Ghareh Aghaj basin, Iran
Abstract
In this paper area under hazard of Meteorological Drought was evaluated using GIS technique. In Ghareh Aghaj watershed, meteorological drought has the most profound effect on the way of living and regional
economy. Hence knowledge of the meteorological drought hazard area of their occurrence and their course is an essential aspect for planning. The purpose of this study was to make a model of the meteorological drought hazard area using GIS. A set of meteorological drought indices were studied and reviewed to define areas under hazard. Meteorological drought indicators used in the present model include: Annual rainfall, climate change, Coefficient variation (CV) of annual rainfall, climate, ratio of the number of arid years with SPI<-1 to the number of total years in each station, ratio of the number of vernal arid seasons with SPI<-1 to the number of total years in each station, and the number of sequential arid years using definition of WMO. The data analyzed have been gathered
from the records, reports and maps published by the governmental offices of Iran. Most of these indicators were performed using average annual rainfall data and average annual temperature of minimum 16 years record of 20 stations. Each of the hazard indicator maps and also final hazard map are classified into 4 hazard classes of drought: mild, moderate, severe and very severe. The final hazard classes were defined on the basis of hazard scores arrived at by assigning the appropriate attributes to the indicators and the final hazard map was prepared by overlaying different hazard indicator maps in the GIS, deploying the new model. The final Hazard Map shows that moderate hazard areas (67% of the basin) are much widespread than areas under severe hazard (37% of the basin)
which are observed in the Southeast of the region.
economy. Hence knowledge of the meteorological drought hazard area of their occurrence and their course is an essential aspect for planning. The purpose of this study was to make a model of the meteorological drought hazard area using GIS. A set of meteorological drought indices were studied and reviewed to define areas under hazard. Meteorological drought indicators used in the present model include: Annual rainfall, climate change, Coefficient variation (CV) of annual rainfall, climate, ratio of the number of arid years with SPI<-1 to the number of total years in each station, ratio of the number of vernal arid seasons with SPI<-1 to the number of total years in each station, and the number of sequential arid years using definition of WMO. The data analyzed have been gathered
from the records, reports and maps published by the governmental offices of Iran. Most of these indicators were performed using average annual rainfall data and average annual temperature of minimum 16 years record of 20 stations. Each of the hazard indicator maps and also final hazard map are classified into 4 hazard classes of drought: mild, moderate, severe and very severe. The final hazard classes were defined on the basis of hazard scores arrived at by assigning the appropriate attributes to the indicators and the final hazard map was prepared by overlaying different hazard indicator maps in the GIS, deploying the new model. The final Hazard Map shows that moderate hazard areas (67% of the basin) are much widespread than areas under severe hazard (37% of the basin)
which are observed in the Southeast of the region.
