Pakistan Journal of Meteorology
Vol. 9, Issue 17: Jul 2012
Rainfall Trends in Different Climate Zones of Pakistan
Salma, S.1, S. Rehman1, M. A. Shah2 Abstract In this paper, the study was conducted across the country to assess the rainfall trend in different climate zones of Pakistan over the past three decades. For this purpose dataset comprising 30 years for the period 1976 to 2005 were acquired from 30 meteorological observatories from different parts of the country. The whole data was analyzed through Analysis Of Variations (ANOVA) along Dunnett T3 test. The result has shown a decreasing trend (-1.18mm/decade) all over the country, which may be attributed to the presence of drought period during 19982001. Stations located in different zones of the country mainly from North, North West, West and Coastal areas respectively show overall significant decreasing trend whereas plain areas and South West of the country have been observed with no significant trend. Adverse consequences of the rainfall have already been observed in Pakistan in the form of droughts and super floods which have badly affected human settlements, water management and agriculture sectors.
Keywords: Rainfall trend, Climate zones, ANOVA test along Dunnett T3 test.
The issue of climate change has emerged very strongly during the last two decades on global scale in view of its projected implications on the environment of vulnerable states. Steadily rising temperature and its impacts on the cryosphere and rainfall are evident in many regions around the world. There are indications that Pakistan has had its share of the large climatic variations that are known to have taken place in northwest India in the past. The dominant component of the climate variations was spatial shifts in the rainfall patterns, associated with fluctuations in the general circulation of the atmosphere in the region (Rodo, 2003).Changes in rainfall pattern directly affect water, agriculture and disaster management sectors. According to the report of Task Force on Climate Change (2010) in Pakistan, the country is exposed to a number of natural disasters, including cyclones, floods, drought, intense rainfall, and earthquakes. In the last couple of decades there has been an increase in the incidence, frequency, and intensity of extreme climatic events: about 40% of the people of Pakistan are highly prone to frequent multiple disasters with variations in rainfall patterns, storms, floods and droughts (Hussain et al, 2010, Oxfam Report on Climate Change, 2011). In most areas of the country, rainfall patterns have become very unreliable and unpredictable, making it difficult for communities to make necessary arrangements for their safety, crops and livestock. For instance on 29th July 2010, the country has faced super flood, after heavy monsoon rainfall hit Khyber Pakhtunkhwa, Sindh, Punjab and parts of Balochistan in over eighty years. In this worst flood, an estimated 2000 people were dead and has damaged or destroyed over 700,000 homes. A record-breaking 274 mm rain fell in Peshawar during 24 hours; the previous record was 187 mm of rain in April 2009. On the other hand, in 1998 to 2001 severe droughts occurred in the southern and central parts of the country. The variability of rainfall has increased geographically, across seasons, and annually in Asia over the past few decades. Decreasing trends in rainfall patterns along Pakistan’s coastal areas and arid plains have also been observed (IPCC, 2007). According to Pakistan Meteorological Department, major parts of Pakistan experience dry climate. Humid conditions prevail but over a small area in the north. The whole of Sindh, most of Balochistan, major parts of the Punjab and central parts of Northern Areas receive less than 250 mm of rainfall in a year. Pakistan has a reasonably good network of observatories having a century of records of the basic climate parameters of rainfall and temperature. Chaudhary...
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