Tải bản đầy đủ - 0 (trang)
2 Rural–Urban Land Use Changes

2 Rural–Urban Land Use Changes

Tải bản đầy đủ - 0trang

15



Remote Sensing of Urban Land Use Change in Developing Countries



291



activity may also be taken into consideration in defining urban areas (also see

Chapter 3). For example, an urban area may be defined in terms of the built-up area

or in terms of the functional area. The functional area includes areas for which services and facilities are provided, and may thus embrace not only the built-up area

but also free-standing settlements outside the urban area and tracts of surrounding

countryside if the population in these surrounding areas depends on the urban center

for services and employment. An urban area may also be defined using population

or buildings density as an indicator of urbanization (Barba and Rabuco 1997; Gross

and Monteiro 1989).

Areas that are not classified as “urban” are typically

the term land

represented as “rural areas.” However, there is no standard

cover describes

definition of rural areas that is generally accepted in policy,

the type of

research, and planning, which is at least partially due to the

biophysical

increasing integration of rural and urban areas through

cover observed

commuting patterns and urban and suburban expansion.

on the Earth’s

Different definitions are in use that are each based on difsurface, while

ferent criteria, different levels of analysis, and different

land use refers

methodologies. Most definitions, however, classify rural

to the manner in

areas based on population density, level of urbanization,

which certain

adjacency and relationship to an urbanized area. Some defiland cover types

nitions also take into account the principal economic activare employed or

ity in an area (RPRI 2004; Cromartie and Swanson 1996).

managed by

For the purposes of this chapter, “rural areas” are defined

humans.

according to the International Institute for Environment and

Development (IIED 2004), which define rural–urban interactions as “linkages

across space (such as flows of people, goods, money, information and wastes) and

linkages between sectors (for example, between agriculture and services and manufacturing). In broad terms, they also include ‘rural’ activities taking place in urban

areas (such as urban agriculture) and activities often classified as ‘urban’ (such as

manufacturing and services) taking place in rural settlements.” As a result of continued population growth, departure from agricultural systems, and industrialization, urban areas have been sprawling at the expense of rural areas (e.g., forest

land), ultimately causing the degradation of the physical environment. In order to

ensure that urban areas do not encroach on valuable agricultural land, that agriculture occurs in suitable locations, and that urban development does not cause the

degradation of adjacent agricultural lands, it is crucial to analyze rural–urban land

use changes (CCRS 2003).



15.3



Urbanization in Developing Countries



A developing country (or a least developed country) is a country that has not

reached the stage of economic development characterized by the growth of industrialization. In developing countries, national income is less than the amount of



292



a developing

country is a country that has not

reached the stage

of economic

development

characterized by

the growth of

industrialization



D. Maktav and F. Sunar



money needed to pay for domestic savings, population

growth is usually faster than in developed countries, and

most people have a lower standard of living with access to

fewer goods and services than most people in high-income

countries. In developing countries, urbanization is a key

process. Three main causes have been identified for urban

population growth (Gross and Monteiro 1989; Barba and

Rabuco 1997):

• Rapid overall natural population growth

• Rural-to-urban migration

• Reclassification of rural areas as urban areas



Natural population growth in cities, in addition to transformation of rural to urban

areas, accounts for an average of 61% of the urban population growth in developing

countries. Rural-to-urban migration accounts for 39%. However, differences in urban

population growth exist within and between countries and regions in the world. For

example, in Latin America, where the urbanization level is already high, natural

population growth is likely the most important contributor to urban population growth

(Rossi-Espagnot 1984). In contrast, sub-Saharan Africa and parts of Asia are primarily characterized by high levels of rural-to-urban migration and urban growth.

Developing countries contain a rapidly increasing proportion of the world’s largest metropolitan areas. In 1975, 10 of the largest metropolitan areas were in developing countries. In the 1980s, 22 of the 35 largest metropolitan areas, containing

about 45% of the world’s metropolitan population, were in developing countries.

By 2000, 25 of the largest urban populations were in developing countries. By the

year 2010, it is projected that over 50% of the world’s population will inhabit urban

areas, whereby the majority of the urban population growth is expected to be concentrated in developing countries.

The growth rates of urban populations vary across regions. In Africa, the world’s

most rapidly urbanizing region, the annual urban population growth rate reached as

high as 5.5% during the period 1985–1990. By 2025, it will still be around 3%.

Alternatively, in Latin America, the average urban population growth rate declined

from 3.9% (1970–1975) to 2.9% (1985–1990) and likely to approximately 1.45%

(projected for 2025). In 1990, Latin America was the most urbanized region in the

developing world, with 72% of its people living in urban areas. In Asia, the annual

rate of urbanization was 3.1% during the period 1985–1990. This rate is expected

to decline to 1.1% during the period 2020–2025 (Cepede 1984; Gross 1990; Gross

and Monteiro 1989).

According to the World Bank’s report, “World Development Indicators 2000,”

the share of urban residents in the world’s total population (both developed and

developing countries) rose from 40% in 1980 to 46% in 1999. China, the world’s

most crowded country, accommodates the highest urban population: in 1999, 400

million Chinese were urban residents. Second and third to China are India (279

million urban residents) and the US (210 million urban residents), respectively.

Turkey, the country in which this chapter’s study area is located, ranks is the 14th



15



Remote Sensing of Urban Land Use Change in Developing Countries



293



most urbanized country, whereby the proportion of people living in urban areas

climbed from 44% (19.6 million in 1980) to 74% (47.7 million in 1999). The random and rapid urbanization in Turkey during the past two decades has caused

pressing problems such as higher death tolls in earthquakes and inadequate education and health services (WBG 2000).

Formal settlements “refer to land zoned residential in city master plans or occupied by formal housing” (UN-HSP 2002). In contrast, informal settlements are

defined as: “(i) residential areas where a group of housing

informal

units has been constructed on land to which the occupants

settlements

have no legal claim, or which they occupy illegally, and (ii)

represent illegal

unplanned areas where housing is not in compliance with

or unplanned

current planning and building regulations” (UN-HSP 2002).

residential areas

Informal settlements in developing countries are typically

not in

located on the fringes of cities and characterized by a “dense

compliance with

proliferation of small, make-shift shelters built from diverse

regulations, and

materials, degradation of the local ecosystem and by severe

are typically

social problems” (Mazur and Qangule 1995).

characterized by

According to a report of the UN Human Settlements

a complex mix

Programme on human settlements (UN-HSP 2002), 30–60%

of social and

of urban residents in developing countries live in informal

environmental

settlements. However, accurate population estimates and

problems

maps of these areas are scarce or nonexistent, making it difficult for authorities to enhance the situations of these areas.

Aerial photography, satellite data or land use maps can be used to evaluate the area

occupied by informal settlements. This is typically complemented by mapping applications incorporated into Geographical Information Systems (GIS) and global positioning systems (GPS), which are increasingly used to provide ground truth data.



Assessing Urban Land Use Change in Developing Countries

Over the years, aerial photography has been successfully utilized for mapping,

monitoring, planning and development of urban sprawl, urban land use and

urban environment. For reasons of their widespread availability, stereo

and revisit capability, frequency of update and cost, reliable and accurate

data, however, the focus of urban remote sensing research has shifted more

towards the use of digital satellite images such as IKONOS, QUICKBIRD,

EROS, LANDSAT, SPOT etc. (Donnay et al. 2001). As discussed in earlier

chapters, some characteristics of the satellite sensors, for example spatial

and spectral resolutions, influence their applications for mapping change in

urban areas.

For example, crop and harvest forecasts are especially useful in developing

countries. LANDSAT data can be used very successfully in identifying crop



294



D. Maktav and F. Sunar



types and predicting harvest times with 90–95% accuracy. This facilitates the

accurate forecasting of possible famines and helps put emergency measures

into place well in advance. Another example is related to the informal

settlement areas in the cities of the developing countries where remote sensing

can play an important role by virtue of its repetitive and synoptic coverage that

helps create a base map for many governmental organizations in a very rapidly

and haphazardly growing urban area. One can monitor urban growth, locate

slums and identify the physical characteristics of the slum areas in developing

countries by means of interpretation of high resolution satellite data (Sur et al.

2003; Seto and Duong 2002; Ehlers et al. 2002). The range of image processing

techniques generally used in land use change analysis encompasses various

operations, including geometric, radiometric and atmospheric corrections,

image compression and enhancement, spatial filtering and many of the

image processing techniques discussed in earlier chapters. Change detection

procedure, where two or more images are compared to determine differences,

involves the use of multispectral data sets to discriminate areas of land use

change between dates of imaging. The reliability of the change detection

process may strongly be influenced by a number of environmental factors

that might change between image dates. Two of the main methods are: image

differencing, where data from one date are simply subtracted from those of

the other (the difference in areas of no change should be zero). On the other

hand, image ratioing involves computing the ratio of the data from two dates

of imaging. Here, ratios for areas of no change should have a value of 1

(Lillesand et al. 2004; Jensen 2000; Sunar 1998; Jurgens 2000; Treitz and

Rogan 2004; El-Raey et al. 1995; Gibson and Power 2000; Green et al. 1994;

Mass 1999).

Vegetation indices are another common family of techniques used to

monitor change in environmental conditions within urban settings. Vegetation

indices are defined as dimensionless, radiometric measures that function as

indicators of the relative abundance and activity of green vegetation, often

including leaf-area index, percentage green cover, chlorophyll content, green

biomass, and absorbed photo synthetically active radiation. There are more

than 20 vegetation indices in use in the literature. Many are functionally

equivalent in information content, while some provide unique biophysical

information. One of the most commonly used vegetation indices is the

Normalized Difference Vegetation Index (NDVI). It is formulated as (NIR −

R)/(NIR + R), where NIR, and R represent data from infrared and red bands.

The NDVI is preferred to other vegetation indices for global vegetation

monitoring because it helps compensate for changing illumination conditions,

surface slop, aspect, and other extraneous factors (Lillesand et al. 2004;

Jensen 2000; Harrison and Jupp 1990).



15



Remote Sensing of Urban Land Use Change in Developing Countries



15.4



295



Example: Analysis of Urban Growth in Istanbul, Turkey,

Using Multitemporal Satellite Data



Istanbul, the third-largest city in Europe, extends over both banks of Bosphorus, the

strait that separates the European and Asian continents. The city is home to about

one-fifth of Turkey’s population (12 million inhabitants) and it contributes with a

higher share in Turkey’s economy (Gür et al. 2003). During the last five decades,

unplanned migration and industrialization have metamorphosed the city to such an

extent that it seems to have almost forgotten its 2,500 years of historic heritage

(Baytın 2000; ESA 2001).The following sections demonstrate how multitemporal

satellite imagery, digital image processing techniques, a 1984–1998 population database, and ground data have been used to characterize the effects of urban growth on

land use and land cover changes in Istanbul in general and on agricultural land in

the district of Bỹyỹkỗekmece, a suburb of the mega-city Istanbul, in particular.



15.4.1



Study Area



Bỹyỹkỗekmece (centered at 41 03Â N, 28 45Â E), one of the 32 administrative districts of Istanbul, has been subject to rapid urbanization over the last few decades,

primarily due to increased migration from the Black Sea regions of Turkey (DIE

2000). Bỹyỹkỗekmece encompasses an area of 225 km2, including the Bỹyỹkỗekmece

Lake, and is located along the north shore of the Marmara Sea. According to the

1997 census, the district’s population is approximately 300,000. Population densities

are highest in the coastal regions. Bỹyỹkỗekmece had eight administrative subdistricts (Kavakl, Yakuplu, Kraỗ, Gỹrpnar, Esenyurt, Mimarsinan, Kumburgaz,

and Tepecik) and contained five villages (Hoşdere, Türkoba, Çakmaklı, Karaaaỗ,

and Ahmediye) (Fig. 15.1). However, the administrative boundaries of Bỹyỹkỗekmece

has been restructured over the years. For example, the village Güzelce is part of the

Kumburgaz sub-district, and village Hoşdere was renamed Bahỗeehir after growing

to become a separate sub-district in 1999.



15.4.2



Data and Methods



This case study utilized a variety of datasets. Population data for 14 administrative

units in Bỹyỹkỗekmece and covering the time period between 1970 and 1997 were

derived from the Governmental Statistical Institute reports (DIE 2000), and are

shown in Table 15.1 below. Population changes over the 1970–1985 and 1985–1997

time spans are listed in Table 15.1 and shown graphically in Fig. 15.2.

GIS data layers (vector data) of the Bỹyỹkỗekmece district, its villages, subdistricts, and the coastline were obtained from the Bỹyỹkỗekmece Municipality

in AUTOCAD DXF format. Multi-temporal satellite data (raster data), including



296



D. Maktav and F. Sunar



Fig. 15.1 Map of the Bỹyỹkỗekmece district (numbers and brackets indicate the administrative

transformation dates of villages into sub-districts)



LANDSAT Thematic Mapper (TM), SPOT P and IKONOS XS & P image data

were also obtained and are described in more detail in Table 15.2.

The multi-temporal LANDSAT TM data (1984 and 1998) were rectified based

on 1:25,000 scale topographic maps using an automated registration process



Tài liệu bạn tìm kiếm đã sẵn sàng tải về

2 Rural–Urban Land Use Changes

Tải bản đầy đủ ngay(0 tr)

×