Chapter 2- Background of Urbanization and Remote Sensing of Urban Environment

Transcription

1 ... Chapter 2- Background of Urbanization and Remote Sensing of Urban Environment 2.0 Introduction This chapter discusses two conceptual bases relevant to this research. Urbanization pattern, distribution of urban population in Sri Lanka and remote sensing in the urban context are discussed. The urbanization process in Sri Lanka, the rate has been very low compare to other developing countries in the region (United Nation 1980). The rural to urban migration has not been significant until 1970s in Sri Lanka (Mendis 1982). In the past, p~:rticularly before 1 970s the urban sector did not play significant role in the Sri Lankan economy~perera 1 996). After 1970s, following the adoption of open economic policy. there has been a dramatic chan~..ijrl. this scenario ~~h"fch witnessed gradual increase in the level of urban population (l~fxon._;:~. ~'!!" r996). At this juncture, an analysis of the patterns, changes and trends of urban -ulation will become useful in constructing an overall comprehension of urban phenomena in Sri Lanka. On the one hand, the non availability of census data with regards to the one third of the territory of the country, the north and east for the last 30 years poses many difficulties in estimating the dimension of urban scenario. On the other, the criteria defined to demarcate the urban areas in Sri Lanka comprise another problem. 2.1 Background of Urbanization Meaning of urbanization Urbanization means the process of becoming urban; a complex process of change affecting both people and places. Its main dimensions are: a progressive concentration of people and activities in towns and cities, thereby increasing the general scale of settlement, a change in the economy of a country or region, whereby non agricultural II "'

2 activities become dominant, a change in the structural characteristics of population, spread of urbanism beyond the built up areas of towns and cities, thereby reducing rural dilution, the transmission or diffusion of change of economic, social and technological factors down the urban hierarchy and into the rural areas. Urbanization does not always take the same form, nor does progress at the same rate anywhere (Siddhartha and Mukhe~jee 2000) The definition of urban.. In Sri Lanka, 'urban' status is conferred on an area by the minister in charge of local government purely for local administrative purpose" "However, ministerial discretion seems to be based on the nature of development of the locality or its amenities and urban character" (Mendis 198~ In this connection, tlll).se. areas which ar~ned as 'urban' '_~~A.' are,;lassificd administratively as Municipal and U[bcm Councils. Appendix A shows the list of criteria in use to define urban areas in different countries. An over view of the system of local governance in place, may shed light on the controversies in the computation method of urban population in Sri Lanka. There is a close relationship between the urban population and system of local government in operation which is the basis of the calculation of urban population. Before 1987, the entire country was under four categories of local governance, Municipal Councils, Urban Councils, Town Councils and Village Councils (Government Publication Bureau 1999). Municipal Councils, Urban Councils and Town Councils were considered as urban areas and the people who lived there were computed into urban population. The Village Council alone was considered as rural area. This system of local governance was reformed in 1987 resulted the Town Councils and Village Councils were merged together forming the Pradeshiyasaba which is considered to be rural local authority areas. Most of the Pradeshyasabas in the country comprise urban and rural characters. 12

3 l... After 1987, the urban people who had lived in the Town Councils are categorized as rural population. There are Pradeshyasabas which are more urbanized than some Urban Councils. There are Urban Councils which have more rural character than some Pradeshyasabas (Government Publication Bureau 1999). This reformation made substantial impact in the calculation of urban population and does not represent the actual urban population in the country. The growth rate would be higher than estimated significantly, if there is any change in the criteria used to define the urban status (Mend is 1996). Table 2.1 shows the total urban population and its percentage in Sri Lanka in 1981 and llrban population in Sri Lanka According to the CensJ,IS and Statistics of the country, the urban population in 1981 was "'It 3.2 million persons (Census Report 1981) anttthis figure dec lin~ 2.46 million in. ~.lfs., (Census Report 2001 ). Statistically it ;-e~t as dramatic decline in the level of urban population, this was due to the change~ the system of local government after Whereas the actual population increased more than that was in According to the estimation of average population increase per decade, the total number of urban population increased to 320,000 per decade before the independence and 620,000 after the independence per decade (Mendis 1996). The share of urban population was less than 25% until This has changed to 24% in 1991 and 28% in It is expected that the urbanization rate in the country would be higher than that was experienced in the past decades (Mendis 1996). It is estimated that the share of urban population by the year 2015 would be 35% of the total population (Perera 1996). The annual growth rate of urban population during was 1.2% (Mendis 1996). The low level of growth was attributed to the rural development measures of successive government in power in the country and the urban economy was too weak to attract rural population (Mendis 1982)

4 Table 2.1: Urban Population in Sri Lanka in 1981 and 2001 ('000) Districts 1981 % 2001 % Colombo , Gampaha ,- i Kalutara lkandy I Matale Nuwara Eliya I I I I I Galle Matara Hambantota Kurunegala Puttalam i Anuradhapura I 41.7 I I Polonnaruwa i 20.8' I i Badulla 'it i Moneragala 6 ~ ~ C~ - - Ratnapura 59.2 ' Kegalle Am para Kilinochchi - - Mullaitivu Vavuniya Mannar Jaffna Trincomalee Batticaloa Total ,463 I Source: Census of Population Report in 1981 and 2001 Note: In the Districts of Polonnaruwa and Moneragala, there were no any urban local bod1es which were considered to compute the urban population in Census in 2001 was not carried out in the Districts of North Eastern Provinces. The growth rate of urban population which was decreasing after the independence again increased to 2.4% during periods while the total urban population is increasing (Perera 1996). Actually this increase was two times of the increase of the previous period. This was due to the changes in the government policy with respect to 14

5 the devolution of power from center to the periphery paved the way for regionalized industrial development. That means the regions with much industrial inputs attracted surplus labor forces from rural areas (Dixon 1996). Figure 2.1: Total and Percentage of Urban Population in 1981 and 2001 in Sri Lanka Figure i 1500 r i 1000 ~ ~ 500 Urban Population in 1981 and ~ Jib ~ (~,_,'b 'b ~'b 'b ~,r~ 'b 'b ~ ~ e,...,..._-? ' ~v <(J""' ~~ ~, :.,i-,.~' 1"',. ~.~ ~7> ~rt; ()'~ 7>~-Q ~7> ~7> ~7> ~'>~rt; ~7>-Q liji ~'b'q 'tr~q ~~ ~7>~ ~0~7> 0 ~~ ~.::>, 7> ' ~... ~ - ~ 't(-~ ~ Source: Preoared bsed on the Reoort of Census of Pooulation and 2001 Gl Ill)... "' c Cll u... Cll c. c 0.. "' "5 a. 0 a. Percentage of Urban Population in Sri Lanka in 1981 and r ] ~~~ I ':.Qo ~7> ~e, ~e, o'-7> ~~,:i-7> ~7> ~e, <f.~7> ~~7> ~o'l> ~o~ ~~ ~~ 07> ~<:-~ ~~ ~:~ t..'l>q; ~e-~ oc:' ~v~ '\7> s-t.'r> c.,o ~7> 1$> ~.::> ~~ ~'l;.~~ ~7> o..'r> ~ ~o _,.._o ~ v ~ ~0 ~ Source: Prepared based on the Report of Census of Population in 1981 and r

6 2.1.4 Urbanization pattern in Sri Lanka Due to various factors, the urban population in the country was concentrated unevenly spatially and temporally. Census data relevant to the sectoral population shows that most concentration was in the south western part of the country (Mend is 1996). This pattern was reflected not only in the total population and but in the urban population as well. Even in the south western region, the concentration of population was polarized around the City of Colombo (Mendis 1996). The growth rate of urban population of south western region was lower than that of rest ofthe country. 30% ofthe areas in the District of Colombo were urbanized and 25 % of Jaffna 33% of Trincomalee and Batticaloa were urbanized in There were 8 towns with over 50,000 populations in 1971 and this number increased to 10 in In 1981, only the City of Colombo had over 500,000 populations an~ there were 5 towns ~hich had over 100~ not more than p ~ ~ # 200,000 persons (Mend is ' 1982). There were 4_~w~ich had the population between 50,000 to 100,000 (Mend is 1982). Except t~e :MJna town, all other to:vns were located in the south western part of the country particularly in the Colombo District. Table 2.2: Changes of Urban Areas and Urban Population in Sri Lan-ka Year Number of Total Pop Urban Pop % Inter censal Urban Increase% MCs UCs LBs TCs PS Urban Total Urban Places Pop Pop ,400, , ,759, , ,007, , ,565, , ,106, , ,498, , ,306, , ,657,339 1,023, ,097,895 1,239, ,582,064 2,016, ,689,897 2,848, ,256,154 3,195, ,234,123 2,463,215 Source: Compiled based on the Census Report of Department of Census and statistics, 1981 Report of the Commission of Inquiry on Local Government Reform,

7 Most of the urban population has been concentrated in the small and medium towns ( ,000) throughout the country (Mendis 1982) The number of population in district capitals was between 10,000 and 50,000. Till 1981, the urban population in most of the urban centers showed the growth rate lower than the national growth rate. The significant growth took place in the City of Colombo and substantial increase in the Jaffna town. During the last decade also the Colombo continued to dominate its primacy despites fluctuations in the rate of growth. For instance the City of Colombo was three times bigger than the second largest city in the country, Dehiwala - Mt. Lavinia. The City of Colombo as primate city dominates the entire country and this nature of uneven urban development has been the reason for several other towns lacking behind in terms of population and services. The cities and towns in Sri Lanka except the City of Colombo do not have strong economic base stimulate economic growth and generate employments (Perera 19~). This is obvious whell)o<;>king at the land~atterns of the major cities in Sri Lanka: None of the cities~ ~ountry including the City of Colombo is having more than 2% of land depiilfd for industrial usage. In the recent years, there were slightly increase in the contribution of industrial sector to the total economic growth. Uneven spatial distribution of industrial activities keeps _the Western Province more significant in the national economy. In the year 2000, there were 66% of industries and 88% of manufacturing employment found in the Colombo and Gampaha districts. The regional disparity in prosperity is obvious that the Gampaha and Colombo are most prosperous districts in the country and the gap between the rich and poor also is too wide. It also expected that the City of Colombo is to continue to dominate during the fourth coming decades as primate city. This is because of the existing infrastructure facilities and present nature of development is contributing for the dominancy. It was estimated that the population of the City of Colombo by 2015 would be 1.5 million including 400,000 of work forces (Mendis 1996). Further, the population of Colombo Urban area was estimated to be 4.9 million including 1.8 million work forces by 20 15(Mendis 1996). The total population and total urban population were estimated to be 22 million and 7.8 million respectively by the year

8 Figure 2.1-A: Urban Hierarchy in the Jaffna District Urban Hierarchy in the Jaffna Peninsula (2010) +..._'\~,,. tr' r 1 S,.., i. Medium Small Chankalhlhana;Chunnakln { Po1111 Pedro uvely N elloy~dy Kodikaona~ Chavakacllcheri (> 100,000 Town (10,000-20,000' ""'. - ~ol Town ~ ) o:_-;_. ' Ve ~. \ x Figure 2.1-B :Population Distribution in the Jaffna District in 1981 Population Distribution in the Jaffna District in 1981 _l,- 'J ~ { f Legend (No Persons) Source Distroct Secretaroat Jaffna ~~'!"iiiiiiiiiiiiiiil~~~~ Kilometers 18

9 '"1fmtAAV UNJYERSITY OF MORATUWA. SRilAIIk MORATUWA Figure 2.1-C: Population Distribution in the Jaffna District in 2003 Population Distribution in the Jaffna District in 2003 ~~,- ' Legend (No of Persons) Source D1strict Secretariat Jaffna to ~~~iiiiiiiiil~~~~~ Kilome t ers _, ~ ; ~...,., ~-, - Willie Mendis ( 1982) classified the urban co~p~-s-in Sri Lanka as foll~ws; Colombo - Kalutara urban complex Jaffna urban complex Galle urban complex Kandy urban complex Except the Kandy urban complex which had least number of populations, other three were located in the coastal belt of the country. The largest urban complexes were in the western province which was covered by Colombo, Kalutara and Gampaha districts. It can be concluded that the urban population in Sri Lanka was increasing at decreasing rate other than Colombo and other urban centers had a growth rate lower than the national growth. The small and medium towns have dominant role in the urban hierarchy of this country and the City of Colombo continues to dominate as a primate city. 19 OG.,~r;.w v'-v

10 The continuous urban growth beyond the conventional boundary and consequently convergence of contiguous towns are called urban agglomeration. This type of urban scenario is found in Sri Lanka. Willie Mendis (1996) has studied the pattern of urbanized area in the country and classified them into three categories. They are as follows; 1. Contiguous urban agglomeration 2. Corridor city agglomeration 3. Network city agglomeration Contiguous urban agglomeration means that when the town centers continue to grow, the contiguous centers will merge together forming the larger urban areas. There will be more number of urban centers united. In Sri Lanka the urbanized areas centered on the city of Colombo reflects t~ contiguous urban agg~m~ration pattern. ~ '1 ~~ n. 1" - Corridor city agglomeration means that when _thlltiies located in a lin~ar fashion and continue to grow along the transport network which is connecting the cities, and then the urbanized areas are merged together in the format of corridor. The pattern of urbanization in the Southern regions of Sri Lanka reflects the corridor city agglomeration pattern. Network city agglomeration means that the few clusters of cities are connected with another set of clusters of cities via the transport routes. The network of cities in the Kandy - Kegalle - Kurunegalle, Jaffna, Trincomalee represents the network city agglomeration. There are several mono-centric urban centers which are not included in the above pattern. 20

11 2.2 Remote Sensing of Urban Environment Introduction Previous section of this chapter described about the urbanization pattern and trends in Sri Lanka in a broad manner. The spatial distribution of urban population and urban centers were discussed. Under this section, the natures of urban remote sensing and remote sensing application in the urban areas have been discussed. Different spatial resolutions suitable for urban studies also have been explained Meaning of remote sensing Remote Sensing is the ari\nd science of obtainingjnformation about ~ject without ~ ' being in direct physical contact with the obj~der study (Jensen 2009). The -7.: ~ - ~ information about the surface of the earth or a~o-r below the surface_ of the earth is collected by the sensors on board satellite or aircraft. The remote sensing activity measures the electromagnetic energy reflected by the earth surface or any o~jects under investigation. The electromagnetic radiation used in the remote sensing activity may be naturally available solar radiation or artificially generated radiation as in the case of RADAR, LiDAR etc (Lillesand, 2007). Every material is very distinct in case of absorption, reflection and re-emission of incident electromagnetic energy Characteristics of urban environment Urban landscapes mostly comprise dominant man made environment with natural components. The man made environment comprise diverse materials such as concrete, asphalt, metals, plastics, shingles, glass, water and natural component comprise grass, shrubbery, trees and soil. Human society, to improve its quality of life has fabricated 21

12 these natural and unnatural components in different ways to build housing, transportation system, utilities, commercial, industrial and recreational landscapes. Figure 2.2 shows characteristics of built environment of fort area of City of Colombo. Figure 2.3 shows the characteristics of built environment of Lower Manhattan in the New York City. Figure 2.4 shows the characteristics of the rural environment of Oddusuddan, Mullaitivu district. Figure 2.2 Characteristics of Built Environment, Fort Area of City of Colombo. Source: Digital Globe

13 Figure 2.3 Characteristics of Built Environment, Lower Manhattan, New York City. :If Figure 2.4 Characteristics of the Rural Environment, Oddusuddan, Mullaitivu District Source: Digital Globe,

14 The urban environment has distinct characteristics in reflecting the electromagnetic radiation which is basic energy source for the remote sensing. This distinction of urban surface in the interaction of electromagnetic radiation has been studied and that principle is used to discriminate urbanized areas from the surroundings. Spectral reflectance signatures of few urban surfaces are illustrated in Figure 2.5. Figure 2.5: Reflectance Characteristics of Common Urban Materials Reflectance Characteristics of Common Urban l\iaterials Asphalt Shingle <> 0 t:: c:: Iii g ~ c:: e <!) g} 0., ~... p Wavelength JliD As tro~ Healthy Grass Āsphalt Brick(red) Concrete Slate Sensing Grass Source : Re m ote Se nsing of the e nvironment The knowledge on the characteristics of remotely sensed images representing urban areas are used to analysis the images, such as visual and digital image interpretation. urban landscape, comprise mainly of asphalt roads, concrete, parking areas, brick roof, asbestos roof, cemented flat roof and bare soil generally reflect high proportion of the electromagnetic radiation, green, red and near infrared bands. Consequently, on color infrared, False Color Composite images, urban land cover appears as "Gray". The green vegetation appears bright red in the False Color Composite image. Therefore the gray urban signature contrast sharply with vegetated surfaces that appears bright red or 24

15 l':!enta on color infrared images because the vegetation reflects substantial amount of Jr infrared energy while absorbing much ofthe incident green and red wavelength..!.3 Considerations of remotely sensed image for urban application \ ljny factors need to be taken into account of the remotely sensed images for urban, 1 1plication. Resolutions, date of acquisition of the image, cloud cover, view angle are I,'\\ "nportant factors need to be considered. Three types of resolutions need to be Lllllsidered in selecting satellite images are as follows; I. Temporal Resolution ; Spatial Resolution --; Spectral Resolution.\decision on the level of resolution of the images to be used for any survey; depends on two factors. One factor, what method is to be used to extract information from the images either visual interpretation or digital classification techniques. Second factor, for what purpose the information is required. #., Spatial resolution means that the size of a pixel in the raster image which is a basic building block in the image and a basis to identify a smallest object or unit of space. High resolution images can clearly show smallest object or space. The world leaders in providing highest resolution satellite images are of Quickbird (Japanese) image (Pan 0.61 meters, MX 2.4 meters) and IKONOS (American) image (Pan 1 meter, MX 4 meters) (Lillesand 2007). For example, a motor car on an open place can be identified in a high resolution image of this kind. Extraction of urban information from remotely sensed data require have high spatial resolution (::::; 5m x 5m) than high spectral resolution (Large number of bands). For example, local population estimates based on building units count usually require a minimum spatial resolution of m (0.82 ft ft) to detect, distinguish between or identify the type of individual building... 25

16 Higher the spatial resolution of the remote sensing data, the more detail information that can be extracted in the urban environment. Detail mapping of urban materials and their conditions require hyper spectral remote sensing data. Some land cover types for example specific type of roofs and roads pose considerable spectral confusion. Visual interpretation can extract features such as object shape, size, texture, orientation pattern from high resolution images. Figure 2.6 to 2.11 compare the different spatial resolutions Mapping of urban land use and land cover In the survey of urban land use and land cover, remote sensing plays very important role. Existing spatial and temporal resolutions of the satellite sensors greatly satisfy the diverse needs of the land use and land cover information for urban areas.,... '"" The land use refers to the economic importance of the land and the land cover refers to the biophysical nature of the land. For example, a park may be used for recreation but have teak forest cover. In terms of land use, the park is used for recreations but in terms of land cover, it is teak forest. Several sectors such as residential, industrial and commercial site selection, population estimation, tax assessment, development of zoning regulations require land use and land cover information. Urban information collected for one application might be useful in another. Land cover classification is resource oriented. The biophysical materials of the surface of the urban area can be identified from the satellite images. Appendix B shows A Land use, Land cover classification System adopted by United States Geological Survey (USGS) and American Planning Association to be used in remote sensing. Landsat MSS images (30-79 meters), Landsat TM images (30 meters), SPOT HRV images (20 meters) and IRS IC LISS III images (23.5 meters) can be used for effective mapping of urban land use class of Level- I classified by USGS. 26

17 Figure 2.6: Radarsat Images of an Airport (100 meters Resolution) Figure 2.7: IRS IC Images of an Airport (23.5 meters Resolution) Source: USGS Source: USGS Figure 2.8: SPOT Pan Images of an Airport (10 meters Resolution) Figure 2.9: Aerial Photo of an Airport Source: USGS Source: USGS 27

18 Figure 2.10: Quickbird Images of Yokahama Stadium, Japan (Pan 0.6 Meters, MX 2.4 Meters Resolution) Source: Digitalglobe Figure 2.11: Quickbird Pan Images of Boston, USA (Pan 0.6 meters Resolution) Source: Digitalglobe 28

19 Coarse spatial resolution imageries such as A VHRR (1.1 X 1.1 Km), MODIS (250 X 250 m or 500 X 500 m) can be used to extract class I level urban land use at global perspective. Figure 2.12 shows a satellite imagery which shows the urbanization pattern at global level. Figure 2.12: Satellite Imagery of Urbanized Areas at Global Scale Source: USGS 29