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 low in southern parts as compare to northern parts of the country. Because of this, the gap between evapotranspiration and rainfall cause dryness in the region i.e. greater the difference between these two greater will be the aridity of a region. Climate of arid and hyper arid zone is very dry in nature. Due to this dry nature, relatively low rainfall and massive deforestation, the vegetable cover of the areas has decreased distinctively. If this trend continued, the area might become almost desolate. A decrease in rainfall has caused lowering of the ground water which bring drought like conditions to this part of the country and it has serious impacts on the agricultural sector. This is quite unfortunate for our agriculture that evaporative demand and water requirement for crops in whole southern parts of the country is very high as compare to northern parts and it is very difficult to carry out the agricultural activity in these regions.
Climate variability and change profoundly influence social and natural environments throughout the world, with consequent impacts on natural resources and industry that could be large and far-reaching. Climate change due to global warming not only started to impact the weather pattern but also influence the agriculture sector in Pakistan. Pakistan is an agriculture whose majority of the population depends upon agriculture. Glaciers are the big fresh water sources for Pakistan which fulfills the water demands in the agriculture land while...