44-5대지.1사비르c-4 2009.12.31 9:28 AM 페이지605 600DPI 100LPI Journal of the Korean Geographical Society, Vol. 44, No. 5, 2009(605~623) A Classification of Rainfall Regions in Pakistan* Mian Sabir Hussain**·Seungho Lee*** 파키스탄의 강수지역 구분 미안 사비르 후세인**·이승호*** Abstract：This study is aimed to classify rainfall regions in Pakistan. Classification of rainfall regions is essential to understand rainfall patterns in Pakistan. Rainfall patterns have been investigated using a factor and cluster analysis technique by 10-days rainfall parameter. The data used here have been obtained from 32 specific weather stations of PMD (Pakistan Meteorological Department) for the period of January 1980 to December 2006. The results obtained from factor analysis provide three factors and these three factors accounts for 94.60% of the total variance. For a better understanding of rainfall regions, cluster analysis method has been applied. The clustering procedure is based on the Wards method algorithm. Overall, these rainfall regions have been divided into six groups. The boundary of the region is determined by the topology such as Baluchistan plateau, Indus plain, Hindu Kush and Himalaya ranges. Key Words : factor analysis, cluster analysis, 10-day rainfall, rainfall patterns, rainfall regions 요약：본 연구의 목적은 파키스탄의 강수지역을 구분하는 것이다. 파키스탄 강수 특성의 이해를 증진시키기 위해 강수 지역을 구분 하였다. 강수 형태는 순별 강수량 자료를 이용하여 인자분석과 군집분석 기법으로 분석하였다. 연구에 사용된 자료는 파키스탄 기상 청에서 제공하는 32개기상관측소의자료로연구기간은1980년에서 2006년까지이다. 인자분석의 결과 추출된 3개의 인자는 전체 변동의 94.60%를 설명한다. 강수 지역은 강수 특성의 공간적 분포를 이해하기 위해 군집분석을 하였다. 군집분석은 Ward법을 이용 하여 분석하였다. 연구 결과 강수 지역은 6개의 지역으로 구분되었다. 지역의 경계는 Baluchistan 고원, Indus 평야, Hindu Kush 산 맥과 Himalaya 산맥 같은 지형을 기준으로 구분하였다. 주요어 : 인자분석, 군집분석, 순별 강수량, 강수 형태, 강수 지역 1. Introduction continental type of climate than the other part of sub-continent and has a great diversity of climate Pakistan is situated in South Asian region due to different topology and altitude. The local between 24-37°N of latitude and 61-76°E of topology of the country, can describes such as longitude. Pakistan has four Provinces namely, Baluchistan plateau, Indus plain, Hindu Kush, Punjab, Sind, Baluchistan and North West and Himalayas ranges (Figure 1). Frontier Province (NWFP). It has a more Pakistan has four seasons, which are * This work was funded by the Korea Meteorological Administration Research and Development Program under Grant CATER 2008-4505. ** Ph. D. Student, Department of Geography, Konkuk University, [email protected] *** Professor, Department of Geography, Konkuk University, [email protected] -`605`- 44-5대지.1사비르c-4 2009.12.31 9:28 AM 페이지606 600DPI 100LPI Mian Sabir Hussain · Seungho Lee discriminated as following groups; cold season recorded in Punjab and Sind during monsoon. December to March, hot season April to June, Similar, northern mountains and Baluchistan monsoon or summer rainy July to September, receive maximum rainfall during October to and autumn or post monsoon October to March (FAO, 1987). November (Kureshy, 1998). Most of country is In Pakistan, most of the rainfall associated with) arid except the southern slopes of the Himalayas the monsoon winds, the western disturbances and the sub-Himalayas (Shirazi et al., 2006). The and the thunderstorms, but the rainfall does not whole of Sind, a major part of Baluchistan, occur throughout the year. Monsoon wind is the southern Punjab and central part of the northern major source of summer rainfall in Pakistan areas have a climate as arid or semi-arid (Naqvi (Kureshy, 1998). In Pakistan, 50 to 75% of rainfall and Rehmat, 1962). Usually 50% of Pakistan is is associated with the monsoon (Kazi, 1951). The arid, 40% semi-arid and 10% area of the country summer monsoon rainfall in Pakistan may vary receives the humidity (Khan, 2002). from 17 to 59% (Luo and Lin, 1999). The The distribution of rainfall in Pakistan varies on monsoon rainfall is more variable than the rainfall wide ranges. Almost 60% of the rainfall is of western disturbances and the rainfall of Figure 1. Physiographic features of Pakistan Source: Orbis Atlas of Pakistan -`606`- 44-5대지.1사비르c-4 2009.12.31 9:28 AM 페이지607 600DPI 100LPI A Classification of Rainfall Regions in Pakistan thunderstorms (Khan, 1962). The western from agriculture point of view very important, disturbances are the major cause of winter rainfall thus a rainfall classification is essential for Pakistan. in Pakistan (Khan, 1993). Pakistan receives a With the increase in population and consequent smaller amount of rainfall, but this small amount food security, it is important to investigate the of rainfall has a large variation. The variations of rainfall patterns and make their classification. rainfall increase from north east (humid areas) to There is not much work has been done in this south-west (arid area) over the Indus plain (Kazi area of prime importance inside the country and and Khan, 1951). outside world. This paper has been conducted In 1951, Kazi has made a detailed study on the which is an attempt to classify Pakistan in Pakistan’s climate and identified the various different regions of rainfall. The main objectives climatic regions. For this purpose, Kazi has of the present study are to classify the rainfall compared some classic climatic classifications regions and identify the rainfall distributional such as, in 1931, Köppen showed, the whole of patterns and their characteristics in Pakistan. Pakistan under the group B of dry climates, The classification and regionalization have a except a smaller area of the extreme northern rich history in the field of climatology. That is, to part of the country. These divisional groups of understand the climatology of any country, Pakistan are BShw, BWhw, BSks, Dfb and ET regionalization is one of the first steps (Periago et types of climate. Thornthwaite (1931), climatic al., 1991). Anyadike (1987) has proposed rational classification indicated Pakistan as arid and semi classification and regionalization based on as arid excluding the northern Punjab and the many climatic elements and factors. Anyadike adjacent Kashmir. In Blair’s (1942) classification, reported, such an approach adapted for the Pakistan falls under four types. This climatic United States (Steiner, 1965), Australia (McBoyle, scheme indicate the arid (desert climate) and 1971), Europe (McBoyle, 1972) and South Africa semi arid except eastern part of Punjab and (Perston-Whyte, 1974). In all such studies Kashmir. Trewartha (1943) follows Köppen regionalization has been achieved by cluster fundamentals in his classification. Trewartha analysis using factor scores. The ideal made major five groups for climate recognizance classification should not only give actual as well. These groups showed Pakistan as an arid boundaries between the macro-climate regions and semi arid region. Miller (1949) classified the but also generate suitable micro-climatic regions climate into seven groups. According to him, (Puvaneswaran and Smith, 1993). The Pakistan falls under three types, Azm, Fi and classification procedures identify the spatial mountain climates. Moreover, Kendrew (1941) configuration, the patterns, the climate has divided Pakistan into four regions such as, characteristics and the climate variability arid low land, arid plateaus, northern sub- (Kulkarni et al., 1992). mountain and Himalayas (Kazi, 1951). Kazi has divided Pakistan into four major climatic regions those are further divided into secondary division 2. Data and methodology of the micro regions. These all classifications are overall climatic classifications, but in all mentioned studies there is no solemn work Rainfall data for 32 weather stations spread which claimed the rainfall classification. over the country during the period of 1980 to The purpose of rainfall classification may be 2006 has been used in this study (Figure 2). For -`607`- 44-5대지.1사비르c-4 2009.12.31 9:28 AM 페이지608 600DPI 100LPI Mian Sabir Hussain · Seungho Lee Figure 2. The location of selected 32 weather stations used in study for period of 1980-2006 this purpose, the daily rainfall data of 27 years rainfall study, security measures can adapt easily has been obtained from PMD (Pakistan in the sector such as emergency plans for urban Meteorological Department). The rainfall patterns sewerage, new construction and tourism. have been investigated by factor and cluster In first step, factor statistical treatment is analysis technique using 10-days rainfall applied on the data and obtained 3 factors with parameter. The 10-days rainfall is addressed as 94.60% that explains the total variance. The early (10-days), mid (10-days) and late (10-days) factors score obtained at the final step in the rainfall of a month. Similarly, graphs have also factor analysis procedure have been used as an showed the 10-days distribution rainfall patterns. input for cluster analysis to produce rainfall This procedure, factor and cluster analysis regions. For clustering, the ‘Equal Euclidean technique using 10-days rainfall parameters is Distance’ method is selected at first, to compute suggested by Lee (1993). the distances between objects. This is the most The 10-days rainfall data is used to identify the frequently used method for type of distance. magnitude of rainfall on short span basis. Similarly, for cluster of regions, the Ward’s (1963) Pakistan is an agrarian country and the 10-days method has been chosen. This method is unique rainfall classification is helpful in planning the from all other methods, because this method can crop seasons, water management, and monsoon easily evaluate the distance between clusters for behavior. Besides, with the help of 10-days an analysis of variance approach. The Ward’s -`608`- 44-5대지.1사비르c-4 2009.12.31 9:28 AM 페이지609 600DPI 100LPI A Classification of Rainfall Regions in Pakistan method is a superior technique (Bunkers and respective statistical function and this is the most Miller, 1996) and has the quality to minimize the popular method for classification.