Research on the effect of urban expansion on agricultural land in ho chi minh city by using remote sensing method

VNU Journal of Science, E arth Sciences 24 (2008) 104-112 * Research on the effect of urban expansion on agricultural land in Ho Chi Minh City by using remote sensing method Tran Thi Van* In$titutefor Environment and Resources, VNU- HCMC Reccived 11 April 2008; received in revĩsed form 13 July 2008 A bstract H o Chi M inh C ity is a One of the biggest citics of V ietnam B eíorc 1945, th e re vvore a b o u t 400,000 in h ab itan ts living in the City D uring the last tw o decadcs, it b ecam e th e b ig g est in d u stria l an d com m ercial center of th e country A ccording to th e statistics in 2005, its p o p u la tio n w a s ab o u t 6.2 m illion poople In th e su b u rb a n areas of the City, p artic u la rly in th e n o rth c rn p art, a g ric u ltu l activities p ro d u c c tho m ain incom c of thesc local residents W ithin tho last 15 ycars, d u c to u rb a n iz atio n and em ig ratio n from o th er provinces, th e p o p u la tio n ex plosion b ec am e a serio u s problem T h e convorsion of agricultural land into residential a re a s h as incroased m o rc an d m ore, causing th e change of lan d -u se structure This p a p e r describes th e capability of re m o te scn sin g for detecting a n d analy/.ing sp atial changes as w clỉ ns q u an tiíy in g rc su lts to sh o w th c u rb a n grovvth process, an d its im pact on th e lan d -u se d istribution in the n o rth e rn p art of H o C hi M inh City Keỵĩvords: A gricu ltu ral land; GIS; Rom ote sensing; S uburban; U rban expnnsion result, an extrem c stress to the cnvironm ent has occurred This is particularly truc in Ho Chi M inh City w here agricultural land has been gradually d isap p carin g each year, converted into urban or related uses Purtherm ore, because of the lack o í ap p ro p riate land use p lan n in g and the m easures for sustainable developm ent, ram pant urban grow th is crcating severe environm ental consequences A lthough Ho Chi M inh Citv has a history of establishm ent and d cv elo p m cn t over 300 years, urbanization has just started from few last decades Ind u stry began to play an im portant rolc m crely in 1960 - 1970 years [6], and then som e urbanized regions w ere obviously on the rise H o u c v e r, the vvar had caused the constrained situation of Introduction O ver the w orld/ the cities cover only about one percent of the cartlVs suríace, but m ost oí the issues h ap p en in g in the cities greatly impact on thc environm ent and global change [7\ U rbanization leads to urban spatial expansion d u e to the dem and for developm ent and housing grovvth, as vvell as íacilities areas to serve hum an life In Vietnam, land use and land cover patterns ve undergone a íundam ental change due to rapid cconom ic developm ent und er its reíorm ative econom ic policies Urban grow th has been speeding up; as a *Tel.: 84-8-8651132 E-mail: lranlhivarầ@>hcinier.cdu.vn 104 Tran Thi Van í V N U Ịourtĩìil o f Science, Earth Sciences 24 (2008) 704-717 urbanization vvith the great concentration of huge population, w hile the in d u stry slowly developed and living Standard w as still low From the end of the 1980s, Ho Chi M inh City has really entered into the pcriod of urbanization and w as speeded u p by industrialization vvith íairly strong progress [6] A griculture and rural areas belong to general socio-econom ic stru ctu re of H o Chi Minh Citv w ith their ad v an tag es of geographical location exist as a su b u rb an of the big scientiíic, technological, industrial and com m ercial city The city has taken full advantages of location, exploited strength of industry, Service, Science and technology to serve the dev elop m en t of ag ricu ltu re and rural areas In recent years, d u e to the requirem ents of city expansion, a part of suburban agricultural land w as urbanized According to developing strategy for a civilized/ m odern and environm ental sustainable City, suburban ag ricu ltu re has intended to tran sío rm into ecological and high-tech agriculture If the urban and urbanization issues had been studied for a long tim e in the w orld and then still have been continued to study, in Vietnam this problem m erely is on research íocus from the m iddle of 90s [2] The monitoring of temporal and spatial changing issues in urban is useíull for m an ag ers and planners to dravv up a strategy for urban suitable dcvelopm ent Traditional m ethods rcquiring extensive labour no t bring the eííectiveness in the rcgional scale becausc of high cost oí íielci m easurem ents Remote scnsing and geographic iníorm ation system s (GIS) has been w idely applicd and has been recognized as a pow erful and effective tool in dctccting urban lan d use and land cover change [4] GIS technology providcs a Aexible environm ent for entering, analyzing and đisplaying digital d ata from v ario u s sources It is necessary to identiíy urban íeatures íor 105 change detection and database developm ent Remote sensing technology can acquire on the gro u n d obịects vvithout touching them Satellite rem ote sensing collocts multispectral, m ulti-resolution and m ulti-tem poral data and turns them into valuable iníorm ation for understanding and m onitoring urban land processes and for building urban land cover datasets [8] Especially, it is useíul to consider the historical developm ent of a region This study uses the Landsat TM and ETM* to extract the built-up land in the city and evaluate the change of agricultural land under urbanization in Ho Chi M inh City T he stu d y area Ho Chi M inh City has a very íavorable geographical location in the centre of the rich Southern region vvith m any resources The city has the com m on adm inistrative boundary with Long An, Tay Ninh, Binh Duong, D ong Nai, and Ba Ria - Vung Tau provinces Its natural suríace area is about 209,502ha, am ong them 45% is the agricultural land The land of the city is íorm ed by old and recent alluvions, having poor fertility of soil, not suitable for developm ent of annual crop production [5] For historical conditions, Ho Chi Minh City vvas íorm crly a kind of m onocentric city Beíore 1975, activities of econom y, íinance, culture, education, com m erce vvere mainly concentrated in District 1, and a part of District Ho Chi M inh City has the íairly rapid speed of urbanization According to statistics, the population density has increased from 552 peoplc/km in 1985 to 2,601 people/km in 2002 (in urban areas about 10,076 people/km 2, in rural areas about 602 people/km 2) N on-agricultural population rate has signiíicantly increased from 83.3% in Tran Tỉĩi Van / VN UỊournal o f Science, Earth Sciences 24 (2008) -ĩĩĩ 106 1985 to 95.2% in 2002 The population grovvth causing population overload in the city has been shovvn not only by the natural increase on the spot, bu t also by the mechanical movem ent from other provinces As a result, there is an indispensable need to im prove, expand and develop the old urban areas in this situation In addition, the city som etim es has not controlled unplanned constructions and urban encroaching expansion on suburban agricultural land in the northern part Thercíore, the study area is íocused on this part This is a region vvith a lot of advantageous conditions for developing inírastructure for residential, commercial and industrial areas H erc is the place vvhere the urbanization process is happening íairly strong in the recent years (Fig 1) Fĩg T he stu d y area M ethodology This study vvas based on rem otely sensed data (satellite im ages), along w ith íields check and existing m aps Land cover p attern s for 1989 and 2002 w ere m apped by using L andsat TM and ETM d ata (Dates: 16 January 1989 and 13 February 2002) Five types of land covcr are identiíied and used in this study, in d u d in g : urban, agricultural land, bare land, shru b /g rass land and vvater As the íirst step, the data prc-processing w as initiated for tw o im ages The im ages vvere geom etrically rectiíied and registcred to the sam e m ap proịection to lay them over each other for change detection The im age registration vvas careíully carried out w ith the RMS errors less than 0.3 pixel to g uarantee the tw o coincidcnt images D ue to lack of atm ospheric m easures d u rin g im age acquisition, the atm ospheric correction w as ignored H ow cver/ these im ages w ere acquired in dry season (in January and Pcbruary) in the study area, so they app eared very clear and cloud íree In this context, the atm ospheric cííccts on these im ages were not signiíicant In ordcr to obtain a high accuracy for thc interpretation results, w e selected thc training sam ples for each gro u p of speciíic object For each group (e.g w ater) som e types of sam ple w ere selected by the spectral signatures in the im ages (e.g vvater 1, w ater 2, etc.) The M axim um Likclihood Classiíication w as carried out for each image A íter testing several tim es to carrying o u t the classiíication as well as ad d in g sam ples for achieving higher accuracy, the íinal results w cre accepted F urther activity is the postclassiíication to group the íragm cntary results in five m ain types of land cover as initial determ ination The coníusion m atrix vvas calculatcd for the stu d y area after m asking the unnecessary outside The overall accuracy vvas about 88% íor the year of 1989, and 86% for 2002 Then, íor analyzing thc nature, rate Tran Thi Van / V N U Ịournal of Science, Earth Sciences 24 (2008) 104-127 and location of u rb an expansion in com pared vvith loss of agricultural land; an im age of urban-residential area w as extracted írom each original land covcr image The urban expansion im age w as íurther overlaid w ith som e geographic reíerence im ages to an alyze the patterns of urban expansion, including im age of district boundary, m ajor roads Results and discusions 4.2 Urban expansion during the pcriod of 1989-2002 The research results shovved that population explosion w as the m ain cause oí urban expansion H o Chi M inh City is the biggest industrial and com m ercial center of V ietn am T h e h ig h e c o n o m ic grovvth an d 107 ab u n d an t cm ploym cnt opportunities caused inílux of labor im m igration According to general dem ographic investigation to ls t April 2004, H o Chi M inh City had 1.8 millions im m igrants in the population total of 6.1 ĩ m illions Local increase of population plus im m igrants m ade the city becom e too stuííy According to statistics, the urban population has increased times írom 1990 to 2005 The population density in urban districts in 2005 w as reported around 10,608 people per square kilom eters [1Ị Due to housing dem and and city developm ent, agriculture land vvas transíorm ed into land for houses, roads, industrial and commercial areas From the source of the D epartm ent of N atural Resources and Environm ent, the main land use structure in Ho Chi M inh City is shovvn in Table and Fig Tablo M ain land use stru ctu re in Ho C hi M inh C ity o v er ycars l.an d u se / Ycar 9 (ha) 0 (ha) 2005 (ha) 1995(% ) 2000 (%) 2005 (%) Total B uilt-up land A gricuỉtural Innd 209,376.00 31,196.34 100,366.37 34,657.58 34,153.02 9,002.96 209,502.00 38,571.07 97,247.78 33,472.15 34,011.29 6,199.54 209,554.00 50,523.72 89,659.21 100 14.90 47.94 100 24.11 33,857.86 33,250.02 2,263.67 16.55 16.31 100 18.41 46.42 15.98 16.23 2.96 Forest W ater U nused land 4.30 42.79 16.16 15.87 1.08 12 10 A rea (h a ) Built-up land Agricultural Forest Water Unused land - land ♦ 1995 2000 ■ * - 2005 Fig T he ch an g cs betvveen b u ilt-u p land and agricultural lan d from 1995 to 2005 by statistics Tran Thi Van Ị VNU Ịonmaỉ o f Science, Earth Sciences 24 (2008) 104-111 108 O ver the vvhole city, the land transform ation w as realized m ainly in the northem part of the City as show n by the results írom rem ote sensing data Fig shovvs that the dense settlem ent presented a rapid expansion and concentrated in urban districts and along the m ain roads in the suburban areas, vvhere the agricultural land yielded to property developm ent Although built-up areas have increased in all directions, it w as m ainly concentrated in the í ' -4 (■ N orth, VVest and East of the city and along the m ainroads Result of L andsat im age interpretation show s that d u rin g 13 years, from 1989 to 2002, agricultural land vvas decreased by 39,329 ha, am ong which 6,045 vvere changed to urban residental land, and 23,065 appeared as bare land since the local íarm ers sold their lands They vvill bc used for íuture built-up purposes (sce Table 2) 4ị " • ? * ■ r ộ V * e ỉ • Ị m - » > • 'i k u r b a n r b a n V V a te r - a te r B a r e U A g r ic u U u r a l l a n d A g r ic u l lu r a l la n d W fv T Ỉ ỳ V * ' H ■ B la n d S h r u b / y r a s s a r e la n d S h r u b / g r a s s l a n d ( a n d 1989 2002 Fig R esults of u rb an expansion in the n o rth e rn p a rt of H o Chi M inh City in 1989 and 2002 from rem otely scnsed d ata Table L and usc tran sío rm a tio n from 1989 to 2002 in th e n o rth e rn p art of H o Chi M inh C ity (ha) lan d Rovv total (2002) C la s s to ta 84.15 892.26 12,860.73 12,860.73 2,200.86 1,550.52 17,276.22 73,998.90 74,060.10 1,556.01 5,297.04 18.99 982.62 7,953.48 7,963.02 851.76 23,065.65 351.45 1,120.59 3,378.15 28,767.60 28,767.78 Shrub / g rass land 81.63 8,661.87 310.23 69.30 9,584.10 18,707.13 18,731.16 Class total (1989) 6,577.02 91,906.38 8,847.54 2,843.55 32,113.35 C lass changes 1,426.14 39,329.01 3,550.50 1,722.96 22,529.25 Im age d iííeren ce 6,283.71 (17,846.28) (884.52) 25,924.23 (13382.19) U rban A gricultural Land YVater Bare land U rban 5,150.88 6,045.48 687.96 A gricultural land 393.93 52,577.37 W ater 98.82 Bare land S h ru b / g rass Tran Thi Van / V N U loum nl o f Science, Earth Sciences 24 (2008) 104-1 ĩ By history, d u e to intensivc urbanization in the suburban districts, such as Tan Binh, Go Vap, Binh T hanh and District 8, residental land becom es rnore and m ore cram ped U nder the íorce of circum stances, some suburban areas w ore changed into íive new urban districts írom 1997 D istricts 2, and Thu Duc have been divided írom Thu Duc sub u rb an district; District from a part of Nha Be and D istrict 12 from a p art of Hoc Mon Beside that, th e d evelopm ent of thc nevv urban areas such as N am Sai Gon helped to extend Ho Chi M inh City in all directions As it is shovvn by the analysis of rem ote sensing d ata in 1989 and 2002, the built-up land increased m ost in districts Tan Binh, Go Vap, Binh Thanh and D istrict 8, vvhere the population is densely located (sec Table 3) T able B uilt-up land increase w ith p o p u ỉatio n District Incrcased In crcascd nrea in p o p u latio n b u ilt-u p total land (k m : ) Tan Binh 20.34 13.49 11.07 G o V ap Binh Thcinlì D istrict 8.25 324,904 Increased p o p u latio n pcr km 205,656 14,517.61 10,418.24 83,864 88,423 4,039.69 4,610.17 The change of agricultural land has happened in the areas w ith available inírastructure, n ea r m ain roads, in the gatcvvay areas of the City, especially in the areas planncd for residential, industrial, commercial zones Effcci ofỉos$ of agricultural land due to urban cxpansion 4.2 Agricultural activities in su b u rb an areas bclong to general socio-econom ic structure of Ho Chi Minh City From the Day of Liberation in 1975, agricultural íields as the city's green bclt have been changed on 109 general dem and oí city developm ent through diííerent stages w ith mission of supplying íresh íoods and a part of raw m aterials for industrial Processing Novvadays, rural areas havc been charged vvith production of higheconom ic-value agricultural goods, accom m odated m arket and export In recent years, d u e to thc needs of expansion of the City, a part of suburban agricultural land has been urbanized Suburban agriculture has a tendency to transíorm into ecological and high-tech agriculture, according to developing strategy of a civilized, m odern and environm ental sustainable city Hovvever, d u e to uncontrollably rapid urban expansion in the year's 1990, loss of agricultural land in rural areas has m ade a change of the unplanned City Agricultural land in Ho Chi M inh City is not only limited in the size but also is poor on quality due to the alum -salted eííect plus uníavourable conditions on topography and water This has inílucnced land exploitation potential on goods oricntation As conscquence, the eííectivencss of agricultural land use in suburban areas has a low er level in com parison to the vvhole country In addition, the average norm of agricultural land distribution for each household was very Iow: 0.32 per household, just equal 2/3 of the average norm of the South-East Region and equal 1/3 of the M ekong Delta This situation is a pressure on suburban íarm ers in keeping agricultural production [6] A ccording to the investigation of Institute of Economic Research in June 1996, the num bcr of íarm ers ovvned the crop land was decreascd by 23% com pared vvith the total land in urbanized areas [6] Due to thc above lim itations, plus the im pacts of urbanization, these íarm ers w ould not hesitate to sell land in o rder to m ake Capital for anothcr type of investm ent They hoped for higher proíits or 110 Tran Thi Van / VNU Ịoumaỉ o f Science, Earth Sciences 24 (2008) 104-111 im provem ent their life in the short term As a result, this circum stance caused the rapid reduction of agricultural land M ost of the yielded land h a s been ch an g e d into the urban uses A lot oí new urban areas has rose jfor satisíaction of housing dem and from population explosion This m ade the city íacing problem s of ecological unbalance and loss of traditional agricultural villages Typically, Go Vap íloricultural village vvas disappeared, now a few points of decorative plant trade exist as the rem inder of this tradition Lovv land areas cultivating vvet rice (such as in D istrict 2) naturally w ere places for balance of the drainage, b u t constructing and concretization process m ade flow to convergent narrovv sevverages; or the altitude raise of new urban areas caused concentration of w ater flow in lovver old urban areas and instant inundation was unavoidably h ap p en in g in the city centers Hovvever, it is w orth to m ention that aíter land selling, the situation of fallowing agricultural land has becom es w idespread in suburban districts This causes the prodigality in land use of the city directions, b u t it was m ainly concentrated in the N orth, VVest and East of thc city and along the m ain roads In the upcom ing years, due to trend of expansion, H o Chi M inh City vvill becom e a special urban vvith population m ore than 10 m illions by 2010 year [3] U rban expansion supplied conditions to disperse the habitants from excessive concentrated areas of inner city districts Hovvever, the uncontrolled sale of agricultural land m akes diííiculty in land m anagem ent u n d er sustainable developm ent In the íuture, it is required a huge am ount of investm ent to im prove the productivity and effectiveness of agriculture in the situation of less rem aincd agricultural areas w ith bad íertility plus uníavourable conditions on topography and vvater resources Finally, although urban expansion cannot be stopped, vvith proper m anagcm cnt and planning it can bc clirected in a desirable and sustainable way, protecting fertile agricultural land and ecological areas, creating green belt for the city A ck n o w led g em en ts C onclusions In this study, rem ote sensing and GIS m ethod vvas developed for evaluation of rapid urban expansion and loss of agricultural land Results revealed a notable increase in urban land cover betw een 1989 and 2002 Built-up areas has increased in all directions bu t it vvas m ore concentrated to the North, VVest, and East of the city U nder im pact of urbanization, land-use types have suííered a lot of changes, especially for the agricultural land The results from rem ote sensing data shovvn that urban expansion has spatially increased in all This pap er w as com pleted within the íramevvork of F undam ental Research Project 719706 íu n d ed by V ietnam M inistry of Science and Technology R eíerences [1] B urcau of S tatistics in H o C hi M inh C ity, Stntisticnỉ yenrbook in 2005, Statistical P ublishing H ouse, H C M C 2006 (in V ietnam ese) [2] D am T ru n g P h uong, Urbnn in Vietnmn, C o n stru ctio n P u b lish in g H ouse, H anoi, 1995 (in V ietnam ese) [3] Decisiotĩ of the Primer M inister No 1570/QD-TT$ nbout approual of mission to adịust the genernl Tran Tìỉi Van / V N U Ịournaỉ o f Science, Enrth Sciences 24 (2008) 104-111 111 pỊanniny on construction of Ho Chi M inh City to 2025, H anoi, 27/11/2006 (in V ictnam esc) in tìo Chi M inh C ity - A proposnỉ of críterion for (41 P.M H arris, S.J V entura, T he intogration of R eport of thc Scỉentiíic Project, Institute of g co g rap h ic d a ta w ith rem otely se n se d im agery Econom ic R esearch, HCM C 1998 (in V ietnam ese) [7] p Vollinga, N H erb, ỉndustriaỉ Trnn$formation: to im p ro v c classiíication in an u rb a n area Photogrnmmetric Engineering and Remote Sensing 61 (1995)993 supporting empỉoỵment situation to District 2, Science Pỉan, IH D P R eport No 12 Bonn: The |5Ị In stitute of E conom ic R esearch an d D epartm ent In tern atio n al H u m an D im ensions P rogram on of C u ltu ro a n d Kníormation of H o C hi M inh G lobal E nvironm ental C hange, 1999 [8] Q.A YVeng, Rem oto sen sin g - GIS cvaluatio n of City, Economic o f Ho Chi M inh City - 30 year construction and development (1975-2005), u rb a n expansion a n d In stitu te of E conom ic Research/ H C M C , 2005 (in te m p e tu re V ictnam ese) Internatiom ỉ Ịournnỉ o f Remote Sensing 22 (2001) 1999 [6] N g u y en Thi T u at, The iĩììpnct o f urbanization process OỈI the socio-economic change o f rurnl arens in th e its im pact on suríace Z hujiang Delta, C hina, ... develop the old urban areas in this situation In addition, the city som etim es has not controlled unplanned constructions and urban encroaching expansion on suburban agricultural land in the northern... to uncontrollably rapid urban expansion in the year's 1990, loss of agricultural land in rural areas has m ade a change of the unplanned City Agricultural land in Ho Chi M inh City is not only... urbanization in Ho Chi M inh City T he stu d y area Ho Chi M inh City has a very íavorable geographical location in the centre of the rich Southern region vvith m any resources The city has the com m on