Estimating Pashtun Sub-Tribal Populations in Mizan District, Zabul Province, Afghanistan Using Quickbird Satellite Imagery and Dasymetric Mapping
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Geographic Information Systems for the Geospatial Intelligence Professional Summer 2008 Capstone Project Estimating Pashtun sub-tribal populations in Mizan District, Zabul Province, Afghanistan using Quickbird satellite imagery and dasymetric mapping Kevin Stofan* 1st Battalion 4th Infantry Regiment, United States Army, APO AE 09173, Hohenfels, Germany Abstract The applicability of using areal weighting and dasymetric mapping of settlements delineated from high resolution Quickbird panchromatic imagery was assessed for Mizan, Afghanistan. Areal weighted values of selected settlements were highly correlated with observed values yielding a Pearson product correlation coefficient of 0.94. Linear regression modeling using observed settlement values and settlement habitable area was used to predict settlement populations throughout the district yielding an R2 of 0.89. Estimated populations were combined with tribal affiliation maps to illustrate sub-district variation in tribal affiliation. Finally, threat maps based on population and tribal affiliation was estimated for routes in the district. Keywords: Dasymetric mapping, Remote Sensing; Quickbird; Mizan; Afghanistan, Pashtun, Tribe, Human Terrain. ________________________________________________________________________________________________________________________ 1. Introduction identified, the two most influential groups in understanding security for this study are the Durrani and Ghilzai supertribes 1.1. Situation (also referred to as groups or confederations). The Durrani tribal confederation is named for Ahmad Shah Durrani considered the Beginning in 2001 the United States, North Atlantic Treaty father of modern Afghanistan (NPS 2007). Afghanistan’s current Organization (NATO), and other coalition allies have conducted president, Hamid Karzai, is a Durranni. The Ghilzai tribal group counter insurgency operations throughout Afghanistan in has historically been an archrival of the Durrannis and include support of Operation Enduring Freedom and the reconstruction some of the major Taliban leaders today, including Mullah Omar of the Afghan government. Insecurity throughout the country (Afsar 2008). varies widely and is most notably correlated with Pashtun tribal areas, often referred to as the “Pashtun belt” in the southern 2. Methods provinces of the country (Afsar et al. 2008). Ground forces in Afghanistan seeking to understand security 2.1. Study Area patterns have recently identified the need to understand anthropologic influences, also referred to as “human terrain”. Mizan district, Afghanistan (32.2N, 66.5E) lies in the western This emerging paradigm in security pattern analysis has forced portion of Zabul province, bordering Kandahar province to the ground commanders and intelligence specialists to understand west. No political boundaries exist below the district level and utilize social science tools and techniques not normally in however, the population is naturally divided into several their training. This paradigm has spawned efforts to map and settlement “clusters” which residents often consider and refer to quantify tribal populations in areas of high insecurity, often a as their geographic unit of residence. Clusters are naturally difficult undertaking due to the remote location of many grouped by physical terrain, mainly topography, and may consist settlements. of as few as three towns. Tribal affiliation is often heterogeneous within a cluster. The 96 settlements (AIMS 2008) identified in 1.2 Pashtun Tribal Overview Mizan reflect the district’s agrarian lifestyle, with densely concentrated dwellings often surrounded by orchards, crop Pashtuns are considered to have developed the largest tribal fields, and rudimentary irrigation systems (Figs. 1-3). society in the world (Glatzer 2002). The Pashtun tribal society is The physical geography of the district is dominated by composed of a complex system of confederations, groups, tribes, topographic features with elevation in the district ranging from sub-tribes, and clans. Although several groups have been 1200-2800m. The most dominate hydrologic feature in the _________ *Corresponding Author. E-mail address: [email protected] (K. Stofan). 2 Stofan / Geographic Information Systems for the Geospatial Intelligence Professional Summer 2008 district is the Arghandab River which flows in a general southwestern direction and has a drainage basin which encompasses the entire district. Many terrain features in the district are the result of hydrologic processes and consist of Fig. 2. Typical Mizan dwelling. Fig. 1. Mizan district settlements. rocky mountainous areas, deep valleys, seasonally flooded streambeds and moderately sloped hills. Irrigated orchards and fields consisting of almond (Prunus dulcis), pomegranate (Punica granatum), opium poppy (Popaver sominiferum) and wheat (Triticum spp.) dominate the area’s vegetation. These man-made, typically monoculture vegetated areas are mostly located in low-lying areas adjacent to human dwellings. Man- made structures in the district are composed of earthen materials and are usually clustered in low-lying valleys. No modern transportation network exists in the district and roads are limited to hard-packed, dirt paths. 2.2. Background Due to the extremely remote and rural location of Mizan district, government influence is very limited, including Fig. 3. Sept. 17, 2007 Quickbird image of the area seen in Fig. 2. collection of population statistics. Census statistics in areas such as Mizan are typically conducted using centralized meetings of Tribal affiliation in Mizan district has been reported by several town elders called shuras. The UNHCR has obtained population researchers and agencies at the district-wide level. Data on tribal statistics for Mizan from shuras conducted in 1990 and 2003 of affiliations below the district level is best acquired from local 9,743 and 13,747 respectively (UNHCR 2003). Additionally, the officials who have lived or worked in the district (Younis & Afghan Central Statistics Office reported a population of 21,162 Stofan 2007). Mizan has typically been identified as Hotaki in 2006. In addition to these estimates, many ground Ghilzai Pashtun (NPS 2008), however, data collected recently commanders and provincial reconstruction teams have describes a more heterogenic tribal landscape (Younis & Stofan conducted informal village assessments and town censuses. 2007). 2.3. Classification Scheme 3 Stofan / Geographic Information Systems for the Geospatial Intelligence Professional Summer 2008 Residential areas were delineated using Quickbird 3. Results and Discussion panchromatic imagery captured on September 17, 2007. Manual digitization was conducted in a binary manner similar to Mennis 3.1. Areal Weighted Distribution (2003) and reviewed by Wu et al. (2005), where habitable area was delineated as either present or not present. Dwellings in Using the UNHCR (2003) population estimate of 13,747 for Mizan are often collocated with grain storage, walled livestock Mizan district, total population was distributed among towns pens, and other non-living space increasing the difficulty of based on their proportion of total habitable area. Population digitizing polygons. For this reason, all structures deemed as part estimates for nine individual towns in a test set showed high of a dwelling were included, henceforth named “habitable correlation with observed town populations (Table 1). The space”. A total of 826 polygons were digitized (Fig. 4.). To Pearson product correlation coefficient was 0.94 between the assign settlement ownership to delineated polygons, Thiessen two datasets, although a fairly high standard error was observed. polygons were created from settlement center points and 3.2. Linear Regression Model Table 1 Proportional Population Disribution Comaprison with Observed Values Town Population Observed Population Predicted Kawshak 156 63 Mukurak 230 253 Mullah Bustan 107 51 Muryani 185 230 Populzow Selam 265 229 Potey Kalay 415 883 Rabajoy 121 164 Sadarsang 126 104 Sar Kalay 338 587 R = 0.94 R2 = 0.89 SE = 38.35 Linear regression modeling using the nine observed test set towns as the dependent variable and habitable space proportions as the independent variable yielded: P = 0.003A + 112.10 where: P=total population in persons; A=area of habitable space Fig. 4. Mizan habitable space polygons. in m2 (Table 1). delineated polygons located within a given town’s Thiessen Table 2 polygon was assigned to that town. Area Weighted Durrani Populations in Mizan district, Afghanistan Town Population Percent of District 2.4. Areal Weighted Population Distribution Alikozai 3758 27.34% Nurzai 355 2.58% Given the availability of total population estimates for Mizan Popalzai 229 1.67% district the applicability of using areal weighted distribution of Total 4342 31.59% total population to individual towns based on habitable space was assessed. Areal weighted estimates can be very inaccurate since they assume even population density throughout a target area (Fischer and Langford 1996, Briggs et al. 2007). 2.5. Linear Regression Linear regression was conducted using observed population data collected in 2007 and 2008 (Stofan 2007, Sims 2007, Estes 2008). The linear regression model was developed using population as the dependent variable and habitable area in m2 as the independent variable. 4 Stofan / Geographic Information Systems for the Geospatial Intelligence Professional Summer 2008 Table 3 Area Weighted Ghilzai Populations in Mizan district, Afghanistan Town