Classification and Assessment of Aridity over Pakistan During 1960-2009

1554 Words 7 Pages
3. Results and Discussion
The aridity maps was prepared by using De Martonne’s Aridity Index, Thornthwaite’s Precipitation Effectiveness Index, Thornthwaite’s Moisture Index, UNESCO Aridity Index and Erinc Aridity Index. These indices showed that most of the southern parts of the country lie between arid to hyper arid where as northern parts lie between semi arid to very humid zone (Fig-3). Analysis shows the climate of northern parts is more variable as compare to southern parts. The reason in the variability of the climate in the northern parts is that this region received rainfall in summer due to monsoon systems (July to September) and in winter due to western disturbances (December to March). Southern parts of the country receive most of the rainfall in monsoon season while a meager amount of rainfall in winter. This monsoonal rainfall brings relief to moisture stress to some extent but due to low elevation, higher evapotranspiration and day time temperature, dry climate exists through out the year. Therefore, agriculture activity does not depend on rainfall and proper irrigation is required in the form of canals, river and tube wells. Although, monsoon rainfall bring relief to overcome the moisture stress to some extent. However after that it makes difficult for the agricultural to sustain in this climate.
The total annual mean temperature and evapotranspiration in the south of the country is very much higher than that of north. Whereas, the amount of rainfall is very…