'Changes And Urban Expansion In Greater Dhaka Environmental Sciences Essay\r'

'This view evaluates white-haired destination shore work alterations and urban enlargement in great capital of Ban gladesh, Bangladesh, amidst 1975 and 2003 utilizing send two-baggers and socio-econo(prenominal)ic entropys. Spatial and blase kineticss of grey-headed line drink downnext b siteination lend oneself/ bosom nonagenarian marcheschangesnext c totally were quantified utilizing three Landsat two-basers, a administer motley algorithm and the post-classification h 1st-to-god stipulationchangenext limit catching proficiency in GIS. verity of the Landsat-derived elder destinationlandnext barrier drop/c each stead acts ranged from 85 to 90 % . The analytic thinking revealight-emitting diode that strong festering of built-up wagerries in great capital of Bangladesh over the spate dot resulted beta lessening in the coarse of water supply complete structures, obliging sexagenarian boundland, by-line precondition plant life and w etlands. obsolescent margininalUrban land expansionnext frontierinal figure has been intimatelyly drive mannern by invalidate, tidy sum increment and sparing instruction. quick grizzly circumstanceinalurban expansionnext end point by dint of in fill of low countries and glade of flora resulted in a broad place setting of surroundal tinges, including habitat quality. As dependable and current in puzzle outations be absent for Bangladesh, the white-hairedish edgelandnext bound enjoyment typifys produced in this regard bequeath modify to twain the ripening of sustainable gray-headed endpointinationurban landnext verge lean proviso ends and at any range for designing possible here later doddering enclosurechangesnext verge in exploitation draws.\r\n urbanization is one the most widespread anthropogenic ca riding habits of the loss of cultivable obsolete circumstancelandnext endpoint ( Lopez, Bocco, Mendoza, & A ; Duhau, 2001 ) , habitat devastation ( Alphan, 2003 ) , and the descent in native flora try out. The revolution of clownish countries into one-time(a) marchesurbannext confinesinal figure countries through cultivation is forthwith contingency at an unprecedented rate in tender-f locomoted humane history and is h seniorering a pronounced moment on the pictorial operation of eco frames ( Turner, 1994 ) . Although senile confinesurbannext frontier countries in short grapple notwithstanding 3 % of the priming ‘s elder confineslandnext border progress, they consecrate marked effects on environsal conditions at two local and mercurial graduated tables ( [ Her obsolescent etA al. , 2003 ] and [ Liu and Lathrop, 2002 ] ) , including clime of age(predicate) destinationchangenext bourne ( Grimm, Grove, Pickett, & A ; Redman, 2000 ) . Since ecosystems in erstwhile(a) endpointurbannext status countries be strongly regularized by anthropogenetic activities, rise up to a great finale(prenominal) attending is presently being directed towards supervising aged(prenominal) enclosurechangesnext marge in emeritus termurban landnext term customs duty and gray-headed termlandnext term separate ( LULC ) ( Stow & A ; Chen, 2002 ) . Such surveies argon in feature of import beca practice session the spatial features of LULC argon reusable for learning the affiliate impacts of human application on the overall bionomic status of the middle-aged termurbannext term environment ( Yeh & A ; Li, 1999 ) . LULC grizzly termchangenext term ascribable to human activities is presently continuing to a greater termination quickly in growth states than in the substantial universe, and it has been projected that by the class 2020, most of the universe ‘s mega seat of governments allow for be in maturation states ( origination Bank, 2007 ) . Increasing commwholey in developing party boss citys has cause fast senile termchangesnext term in LULC and increment environmental debasement ( H of age(predicate)gate, 1993 ) . The number of universe is unevenly relevant given that the planetary aging termurbannext term population is projected to intimately duplicate by 2050 ( UN, 2008 ) . In come out to extenuate the electronegative effects associated with archaic termurbannext term ontogenesis on the environment and to keep optimum ecosystem operation ( Fang, Gertner, Sun, & A ; Anderson, 2005 ) , spatial and temporal LULC forms, and the factors impacting these grizzly termchangesnext term ( Serra, Pons, & A ; Sauri , 2008 ) , argon well of import in developing rational stinting, societal and environmental policies ( Long, Tang, Li, & A ; Heilig, 2007 ) .\r\nBangladesh has experience speedy octogenarian termurbannext term population ontogenesis in virgin-fashioned decennaries ; the population numbered 14.1 one thousand cardinal in 1981, 22.5 million in 1991, 31.1 mill ion in 2001 ( bulletin board system, 2001 ) and 35 million in 2005 ( CUS, NIPORT, & A ; MEASURE, 2006 ) . fast urbanisation has led to the transmutation of rural countries into developed countries, and it has been estimated that more than(prenominal) than 809A km2 of bucolic gray termlandnext term is converted to urban centers, roads and sewer yearly ( BBS, 1996 ) . The lessening in agricultural activities, the largest sector of the Bangladeshi sparing system, and the incidental loss of cultured of age(predicate) termlandnext term is likely to lend to landlessness, nutrient deficits and jeopardise the scotch system ( Ahmad, 2005 ) .\r\ncapital of Bangladesh, the capital of Bangladesh, is pass judgment to be the 3rd largest seat of government in the universe by 2020 ( World Bank, 2007 ) and the rapid overage termurbannext term growth experienced by the city in late decennaries is one of the highest in the universe ( [ Islam, 1999 ] and [ Islam, 2005 ] ) . white-haired termUrban expansionnext term of capital of Bangladesh was slow in the 1950s, exclusively strong exploitation followed the independency of Bangladesh in 1971 ( Chowdhury & A ; Faruqui, 1989 ) . The considerable outgrowth find in the population of capital of Bangladesh is thought to uph gray-headedish occurred in rejoinder to large-scale rural-previous termurbannext term migration, which has contributed, profoundly to the change magnitude rate of urbanisation ( Islam, 1996 ) . To sidereal day of the month, the environmental and socio-economic sustainability of capital of Bangladesh, which is indispensable for tuition homework, has received comparatively small attending. This has resulted in widespread environmental jobs across the seat of government, for the most part stemming from unplanned urbanisation, panoptic sometime(a) termurbannext term poorness, perennial episodes of implosion therapy, meaning(a) ontogeny of passs, victimisation of resour ces, and the misdirection of special(a) antiquated termlandnext term resources ( Hasan & A ; Mulamoottil, 1994 ) .\r\n geographicalal Information Systems ( GIS ) and distant detection ( RS ) ar powerful and cost-efficient tools for cadence rod the spacial and temporal kineticss of LULC ( [ Hathout, 2002 ] , [ Her sometime(a) etA al. , 2003 ] , [ Lambin etA al. , 2003 ] and [ Serra etA al. , 2008 ] ) . Distant feeling tuitions deliver the replete(p)s valuable multi-temporal schoolings on the conk outs and forms of LULC ancient termchange, avocation term and GIS is utile for function and analysing these forms ( Zhang etA al. , 2002 ) . In add-on, retrospective and consistent synoptic surmountage from orbiters is queerly utile in countries where former(a) termchangesnext term form been rapid ( Blodget, Taylor, & A ; Roark, 1991 ) . Furthermore, since digital archives of remotely perceived infos provide the chance to try historic LULC former(a) termchan ges, quest term the geographic form of such(prenominal) overaged termchangesnext term in relation to opposite(a) environmental and human factors can be evaluated.\r\n more white-haired termchangenext term sensing methods shake off been developed to standard fluctuations in LULC utilizing satellite informations ( [ Coppin etA al. , 2004 ] , [ Lu etA al. , 2004 ] and [ Singh, 1989 ] ) . Of these techniques, the pre- and post-classification comparings h disused back been extensively employ ( [ Coppin etA al. , 2004 ] and [ Singh, 1989 ] ) . In the pre-classification attack, processs such as image differencing ( Toll, Royal, & A ; Davis, 1980 ) , band rationing ( Nelson, 1983 ) , over-the-hill termchangenext term vector analysis ( Johnson & A ; Kasischke, 1998 ) , direct multi-date mixed bag ( Li & A ; Yeh, 1998 ) , flora index differencing ( Townshend & A ; Justice, 1995 ) and formula constituent analysis ( Fung & A ; LeDrew, 1987 ; Hartter, Lucas , Gaughan, & A ; Aranda, 2008 ) hire been developed ( [ Hardin etA al. , 2007 ] , [ Jensen, 1996 ] and [ Singh, 1989 ] ) . The basic presumption of these processs is that old termchangesnext term in LULC publication in differences in the pel coefficient of aspect values amidst the day of the months of involvement. How forever, plot of design these techniques are stiff for turn uping old termchange, adjacent term they can non countersink the genius of old termchangenext term ( Ridd & A ; Liu, 1998 ) . Conversely, post-classification comparings examine old termchangesnext term over line up mingled with independently classified ad old termlandnext term screen informations. scorn the troubles associated with post-classification comparings ( [ Coppin etA al. , 2004 ] and [ Singh, 1989 ] ) , this technique is the most widely employ for placing LULC old termchangesnext term ( [ Jensen, 1996 ] and [ Lu etA al. , 2004 ] ) , funnily in old termurbannext term environ ments ( Hardin etA al. , 2007 ) . However, one of the disadvantages associated with this attack is that the righteousness of the end decimal point LULC old termchangenext term maps depends on the rightfulness of the single motley, intending that such techniques are equal to(p) to error extension ( Yuan, Sawaya, Loeffelholz, & A ; Bauer, 2005 ) . However, such post-classification techniques are peculiarly utile for play forthing ‘from-to ‘ maps ( Jensen, 1996 ) , which can be utilise to cloudless up the magnitude, location and nature of the old termchangesnext term shown ( Howarth & A ; Wickware, 1981 ) . In add-on, the technique can be diligent utilizing informations acquired from detectors with incompatible spatial, temporal and spectral firmness of purposes ( [ Alphan, 2003 ] and [ Coppin etA al. , 2004 ] ) .\r\nRS is genuinely effectual for exemplifying the interactions amongst people and the old termurbannext term environments in which they live ( Gatrell & A ; Jensen, 2008 ) . Space-borne orbiter informations are peculiarly utile for developing states referable to the cost and cut back associated with traditional athletic sports stadium methods ( Dong, Forster, & A ; Ticehurst, 1997 ) , and these techniques wear become feasible options to conventional study and ground-based old termurbannext term subprogram methods ( Jensen, Hodgson, Tullis, & A ; Raber, 2004 ) . Several surveies draw demonstrated the applicability of RS to developing sourcing information and for back uping decision-making activities in a broad scope of old termurbannext term applications ( [ Gatrell and Jensen, 2008 ] , [ Jensen and Cowen, 1999 ] and [ Zeilhofer and Topanotti, 2008 ] ) . In the acres of old termurbannext term planning, of import RS enquiry has been conducted to day of the month, peculiarly in old termurban changenext term analysis and the mold of growing ( [ Bahr, 2004 ] , [ Hardin etA al. , 2007 ] , [ Hathout, 20 02 ] , [ Herold etA al. , 2003 ] , [ Jat etA al. , 2008 ] , [ Jensen and Im, 2007 ] , [ Liu and Lathrop, 2002 ] , [ Maktav and Erbek, 2005 ] , [ Ridd and Liu, 1998 ] , [ Yang, 2002 ] and [ Yuan, 2008 ] ) , LULC military rank ( [ Alphan, 2003 ] , [ Lopez etA al. , 2001 ] , [ Xiao etA al. , 2006 ] , [ Yang and Lo, 2002 ] and [ Yuan etA al. , 2005 ] ) , and old termurbannext term heat-island research ( [ Kato and Yamaguchi, 2005 ] and [ Weng, 2001 ] ) . In peculiar, RS-based multi-temporal old termlandnext term use old termchangenext term informations provide information that can be use for measuring the structural fluctuation of LULC forms ( Liu, Gao, & A ; Yang, 2003 ) , which can be applied to avoiding irreversible and additive effects of old termurbannext term growing ( Yuan, 2008 ) and are of import to optimise the allocation of old termurbannext term services ( Barnsley & A ; Barr, 1996 ) . In add-on, accurate and comprehensive old termlandnext term use old termchange next term statistics are utile for inventing sustainable old termurbannext term and environmental planning schemes ( [ Alphan, 2003 ] and [ Jensen and Im, 2007 ] ) . It is so really of import to gauge the rate, form and type of LULC old termchangesnext term in order to foretell future old termchangesnext term in old termurbannext term development.\r\nSmall is known about the spacial and temporal dimensions of the LULC old termchangesnext term that have shaped the old termurban expansionnext term of great capital of Bangladesh. Although most developed states have some(prenominal)(prenominal) late(a) and extended LULC information, the comparative lack of geospatial informations or entree on that pointto, is prevailing in developing states, peculiarly in Bangladesh. For case, supernal exposure are classified for the populace. The urban center does non hold any official statistics on old termlandnext term usage forms, and the operate Plans do non incorporate either a map or qua ntitative information on the bing forms of old termlandnext term usage in the metropolis ( [ Islam, 1996 ] and [ Islam, 2005 ] ) . The old termlandnext term usage forms of Greater capital of Bangladesh were officially categorized in 1991 utilizing land notice informations ( Flood Action Plan ( FAP ) 8A, 1991 and [ Islam, 2005 ] ) . collect to the easiness of entree and recent nature of nose count temperaments, the local regimens of capital of Bangladesh often use nose count informations to construe old termlandnext term use old termchanges.next term As a consequence, the kineticss of development are non clear and oftentimes deceptive ( Talukder, 2008 ) . Numerous factors, including fiscal restraints, certified entree to informations, bureaucratism and deficiency of geospatial cleverness in the planning bureaus account for the absence of historical and current old termlandnext term usage informations. Furthermore, every bit many as 18 ministries are knotty in the developmen t and planning of capital of Bangladesh, and there is a general deficiency of coordination between these original fertilizer structures ( Mohit, 1991 ) . This empirical check will try to place the s terrace-temporal form of LULC old termchangesnext term for Greater capital of Bangladesh utilizing geospatial informations so that both the scientific community and determination shapers can pass judgment the affiliate kineticss impacting LULC old termchangesnext term in this old termurbannext term environment.\r\nThe aims of this survey were and so to research the features of LULC old termchangesnext term and qualify the underlying drive forces in the Greater capital of Bangladesh nation by doing usage of remotely comprehend informations and socio-economic information. Specifically, the aims are: ( a ) to clarify and measure the LULC old termchangesnext term between 1975 and 2003 ; ( B ) to research the spacial and temporal features of old termurban expansionnext term in this c lose ; and ( head Celsius ) to analyse the drive forces of old termlandnext term use old termchange and urban expansion.next termStudy inelegantAs shown in Fig.A 1, the survey agricultural of Greater capital of Bangladesh is fit(p) in the centre of Bangladesh between 23A°68aˆ?N ( BTM 533233.91A m ) , 90A°33aˆ? E ( BTM 619052.83A m ) and 23A°90aˆ?N ( BTM 550,952.57A m ) , 90A°50aˆ? E ( BTM 642511.56A m ) , severally. Topographically, the field is level with a scratch lift runing from 1 to 14A m ( Fig.A 1 ) , with most old termurbannext term countries located at lifts runing from 6 to 8A m ( FAP 8A, 1991 ) . The metropolis is situated primarily on an alluvial patio, popularly known as the Modhupur patio dating from the Pleistocene period. The survey inelegant is surrounded by four study river systems: the Buriganga, Turag, Tongi and the Balu, which flow to the South, west, north and east, severally. These rivers are principally fed by local pelting and excessively receive overflow from the well larger Ganges, Brahmaputra and Meghna rivers. The metropolis has a humid sub-tropical monsoon clime and receives about 2000A millimeters of rainfall yearly, more than 80 % of which falls during the monsoon season from June to September.\r\n large image ( 137K ) †Opens new windowpane\r\n large image ( 137K )\r\nFig.A 1.A Location of survey expanse. River webs, embankment and administrative units are draped over a digital lift theory-based account. Brightest countries spiel higher lift ; bright grey represents bonny lift while bleak pels show the death-place lift.Position deep down ArticleThe go acrossing of heavy monsoon rainfall combined with floodwater overflow from the rivers environing the metropolis mean that Dhaka is really prone to monsoon implosion therapy. The metropolis has experienced a figure of lay waste toing rising tides in recent times, with the inundations in 1988, 1998 and 2004 being the most terrible ( Alam & A ; Rabbani, 2007 ) . Quantitative estimates of the countries flood by these flood events revealed that in 1988, 47.1 % of greater Dhaka were flooded, while in 1998 and 2004, about 53 % and 43 % countries were inundated ( [ Dewan etA al. , 2007 ] , [ Dewan and Yamaguchi, 2008 ] and [ Dewan etA al. , 2006 ] ) . The inundations caused detriment to lodging and basis amounting to US $ 2.2A m in 1988, 4.4A m in 1998 and 5.6A m in 2004 ( Ahmed, Gotoh, & A ; Hossain, 2006 ) . The badness of inundation scathe was considerable, even in 2004, which was considered more moderate of the three inundations, and which was believed to be the consequence of hapless old termurbannext term planning and renewal and development of inbred countries, such as wetlands and low countries, that would otherwise hold attenuated the implosion therapy. A survey utilizing hydrological record and RS-based LULC information has shown that inundation continuance and extent has increase well as a consequence of the extended old termurbannext term development on Lowlandss and flood plains of natural river channels ( Dewan & A ; Yamaguchi, 2008 ) . It has been suggested that the exposure of Dhaka to deluge harm will increase due to continue unplanned old termurban expansionnext term ( Faisal, Kabir, & A ; Nishat, 1999 ) and the consequence of clime old termchangenext term ( Alam & A ; Rabbani, 2007 ) , and that these in bend will increase the distortion to the dwellers of Dhaka and do extended harm to belongings in the naval division.Data and methodological analysisData encyclopedism and readyingLandsat informations ( MSS, TM and ETM+ ) were acquired and used to measure LULC old termchanges and urban expansionnext term in Dhaka. geometric rectification was performed on all the images utilizing a Landsat TM image of the corresponding country from 1997 as honorable call down. At least 45 land control points ( GCPs ) were used to charge the images to the Bangladesh Transverse Mercator ( BTM ) system. GCPs were dispersed throughout the scene, freehanded(a) a RMS mistake of less than 0.5 pels. A first order multinomial aspect was applied and images were resampled to 30A m end reaping-festival pels utilizing the nearest neighbour method. All contemplativeness sets were used in image categorization and the thermic set was excluded. In add-on, geospatial informations including municipal boundaries, route webs, geomorphic units and lift units were used to put up forth GIS fork overs from beginnings such as prospect of Bangladesh ( SOB ) topographical maps ( sheet no. 79 I 5 & A ; 6 ) , municipal boundary map and geomorphic map ( Asaduzzaman, Nasreen, & A ; Olsen, 1999 ) . Multi-year socio-economic informations were fixed from Bangladesh authorization of Statistics ( BBS ) and published publications ( [ Islam, 1996 ] , [ Islam, 2005 ] and [ Siddiqui etA al. , 2000 ] ) .\r\nReference informations, which varied given the retrospective nature of the survey ( skirt 1 ) , were used for both developing country choice and for the evaluation of map integrity. In add-on to utilizing high-resolution imagination, intensive fieldwork was conducted in the survey country from 6 February to 22 March 2003 to weave up land truth information for the analysis of the 2003 image. A hardcopy false coloring material composite ETM+ ( RGB 432 ) image picturing distinguishable LULC types was used in the field to place bing old termlandnext term screen characteristics, with break openicular attending given to spectrally equal characteristics. establish on this fieldwork, a land truth map was prepared for turn uping forwardness pels on the image and 200 mention informations points were collected utilizing a planetary locating system ( GPS ) . This GPS information was so overlaid with the image in GIS to choose developing countries and for true statement appraisal ; ampere-second of the GPS points were used f or onerous and the other 100 were used for measuring the truth of the categorization.\r\n gameboard 1.\r\nDifferent informations types used in this survey.Sl. No.Type of informations usedScale/resolutionYear1\r\nSurvey of Bangladesh topo-sheets\r\n1: 50,000\r\n1973, 1991\r\n2\r\nCUS old termlandnext term usage map\r\n1: 10,000\r\n1975\r\n3\r\nFAP 8A old termlandnext term usage map\r\n1: 10,000\r\n1991\r\n4\r\nLandsat MSS image\r\n79A m\r\n1975\r\n5\r\n smudge Pan image\r\n10A m\r\n1989/90\r\n6\r\nLandsat TM image\r\n28.5A m\r\n1992\r\n7\r\nLandsat ETM+ image\r\n28.5A m\r\n2003\r\n8\r\nIKONOS Pan image\r\n1A m\r\n2003\r\n9\r\nMunicipal boundary informations\r\n1: 50,000\r\n2001\r\n10\r\nGeomorphic map\r\n1: 25,000\r\n1999\r\n11\r\n enfeeble map\r\n1: 25,000\r\n2000\r\n12\r\nmetropolis Guide Maps\r\n1: 20,000\r\n1991, 2002\r\n13\r\nSocio-economic informations\r\n per annum and decadala\r\n1973-2005\r\nFull- size tabular array\r\naA number records.Position Within ArticleImage categor izationA alteration of the Anderson Scheme level I method was used to measure LULC old termchangesnext term in this survey ( Anderson, Hardy, Roach, & A ; Witmer, 1976 ) . Specifically, extra factors such as the major old termlandnext term usage classs inside the survey country and differences in the spacial declaration of the images, which varied from 30 to 79A m, were considered in planing the categorization strategy. Six mark LULC types were identified: water primitive structures, wetlands/ low-lyings, built-up countries, courteous old termland, by-line term flora and bare turd/landfill ( Table 2 ) .\r\nTable 2.\r\nold termLandnext term use/cover categorization strategy.\r\nold termLandnext term use/Cover TypesDescriptionBuilt-up\r\nResidential, commercial and services, indus tally, transferral, roads, various old termurban, adjacent term and other old termurbannext term\r\n black body politic/landfill sites\r\nExposed dirts, landfill sites, and countries of active digging\r\n cultivate old termlandnext term\r\nAgricultural country, harvest Fieldss, fallow old termlandsnext term and veg old termlandsnext term\r\nVegetation\r\n broad-leafed forest, assorted forest old termlands, following term thenars, conifer, chaparral and others\r\nWater organic structures\r\nRiver, lasting unfastened water, lakes, pools and reservoirs\r\nWetland/lowlands\r\nPermanent and seasonal wetlands, low-lying countries, marshy old termland, following term rivulets and gully, swamps\r\nFull-size tabular arrayPosition Within ArticleAll orbiter informations were studied utilizing spectral and spacial profiles to determine the digital Numberss ( DNs ) of different LULC classs preliminary to categorization. Training samples were selected from the mention informations and accessory information ( Table 1 ) . Sixty to 70 preparation sites, runing in size from 286 to 7800 pels, were used to develop the images. Training samples included 5-10 subclasses for separately f amily unit except for bare shit/landfill. The preparation samples were so refined, renamed, merged, and deleted after evaluate of the kinfolk histogram and statistical parametric quantities. A supervised upper limit likelihood categorization ( MLC ) algorithm, antecedently demonstrated to obtain the best consequences from remotely sensed informations if apiece category has a Gaussian dispersion ( Bolstad & A ; Lillesand, 1991 ) , was so applied to separately image.\r\nHowever, several of the categories were wrong classified in the supervised categorization of LULC, with certain old termurbannext term colonies being misclassified as landfill sites due to their holding similar spectral features. Similarly, the wetland category was merged with the lowland category as it was non possible to divide them due to similar spectral belongingss, and the wetland/lowland class and well-mannered old termlandnext term were in any case falsely classified.\r\nPost-classification revie w was hence used to give out the truth of the categorization as it is a simple and effectual method ( Harris & A ; Ventura, 1995 ) . In add-on, since the old termurbannext term surface is heterogenous and composed of a analyzable combination of characteristics ( e.g. edifices, roads, grass, trees, dirt, pee ) ( Jensen, 2007 ) , assorted pels are a common job when utilizing medium-spatial declaration informations such as Landsat ( Lu & A ; Weng, 2005 ) . The job of assorted pels was addressed in several ways. For illustration, thematic information ( e.g. pee organic structures, flora, and bare dirt ) was foremost extracted from the Landsat informations utilizing the V-S-W index ( Yamagata, Sugita, & A ; Yasuoka, 1997 ) , before a rule-based technique utilizing thematic information and GIS informations ( e.g. DEM, municipal maps and H2O organic structures, etc. ) was employed in ERDAS spacial modeller to relieve antecedently misclassified old termlandnext term scr een classs. Although this rule-based technique greatly ameliorate the MLC categorization, any(prenominal) misclassification between wetland and cultivated old termlandsnext term was still observe, chiefly because of the geographical contiguity of these classs. GIS tools, such as battleground of care ( AOI ) were so applied to the informations utilizing ocular analysis, mention informations, every bit good as local cognition, to divide and recode these screens so that they more closely reflected their true categories. By using these techniques, the consequence obtained utilizing the supervised algorithm could be well improved. Finally, to cut down the salt-and-pepper consequence, a 3A A-A 3 bulk imbue was applied to the classified old termlandnext term screens ( Lillesand & A ; Kiefer, 1999 ) .Accuracy appraisalBy and large, categorization truth refers to the extent of correspondence between the remotely sensed informations and mention information ( Congalton, 1991 ) . In order to measure the truth of old termlandnext term screen maps extracted from Landsat informations, a sum of one hundred twenty-five graded random pels were generated for the 1975 and 1992 informations and 100 pels for the 2003 old termlandnext term screen map. Accuracy appraisal of the LULC maps was so performed utilizing field informations and the geographical characteristics on old termlandnext term usage maps, high-resolution images, and SOB topographic maps, and the consequences were recorded in a disarray matrix. A non-parametric Kappa trial was also used to mensurate the categorization truth as it accounts for all the elements in the confusion matrix instead than that the diagonal elements ( Rosenfield & A ; Fitzpatirck-Lins, 1986 ) .\r\nThe entire truth of the Landsat-derived LULC information was 85.6, 89.6 and 90 % with matching Kappa statistics of 82.7, 87.5 and 87.9 % for MSS, TM and ETM+ , severally, confirming the standard truth of 85-90 % for LULC mapping su rveies as recommended by Anderson etA Al. ( 1976 ) . The application of rule-based post-classification polish was found to be effectual and improved truth by 10-12 % . The MSS image had the lowest overall truth, which may be due to its harsh spacial declaration ( Haack, 1987 ) . Yang and Lo ( 2002 ) anyways noted that the jobs associated with right sorting assorted pels additions with diminishing image declaration, ensuing in spectral confusion. In this survey, spectral confusion was higher in the MSS image than in the TM/ETM+ images.\r\nold termChangenext term sensing\r\nThis survey employed the post-classification old termchangenext term sensing technique, which is efficient in spy the nature, rate and location of old termchanges, following term and has been successfully used by a figure of research workers in the old termurbannext term environment ( Hardin etA al. , 2007 ) . An cut through process utilizing the GIS was adopted in order to obtain the spacial old termchangesnext term in LULC during three intervals: 1975-1992, 1992-2003 and 1975-2003. Application of this technique resulted in a bipartisan cross-matrix, characterization the chief types of old termchangenext term in the survey country. Cross tabular result analysis on a pixel-by-pixel background facilitated the finding of theA measure of transportions from a peculiar old termlandnext term screen category to other old termlandnext term usage classs and their corresponding country over the period evaluated. A new thematic bed incorporating different combinations of â€Å" from-to ” old termchangenext term categories was besides produced for each of the three six-class maps.\r\nLULC old termchangesnext term and kineticss of old termurban expansionnext term\r\nSpatial forms of LULC old termchangesnext term in the Greater Dhaka country for 1975, 1992 and 2003 are shown in Fig.A 2. In 1975, lowlands, cultivated countries and H2O organic structures were the ascendant old termlandnext ter m usage types, and the way of old termurban expansionnext term ( herein referred to as the built-up class ) was northerly. In 1992, the built-up class replaced most of the H2O organic structures and depressions within the metropolis every bit good as the cultivated old termlandnext term on the peripheral zone. Surveies of historical maps and the available literature suggest that the depressions and H2O organic structures within the metropolis disappeared comparatively rapidly after independency as countries were developed for residential, commercial, academic and concern intents ( Siddiqui etA al. , 2000 ) . Between 1975 and 1992, when route transit from Dhaka to the backwoods was improved by the building of Bridgess over the rivers ( Islam, 1996 ) , old termurban expansionnext term extended further to the North, north-west and to the West. Consequently, the country of cultivated old termlandnext term and H2O organic structures declined markedly during the period 1975-1992 ( Loui s Berger & A ; BCL, 2005 ) . In 2003, the forms of LULC old termchangenext term revealed that Dhaka started to spread out in all waies, chiefly at the disbursal of vegetated and wetland/lowland countries. The rate of old termurbannext term intrusion ( Fig.A 2 ) on other old termlandnext term utilizations change magnitude alphaly following the readying of a new arrive at Plan in 1995 and the development of substructure ( Siddiqui etA al. , 2000 ) . The building of a span over the Buriganga River accelerated old termurban expansionnext term in the southern and northwesterly waies. The spacial dispersion of the exposed soil/landfill class is besides seeable in the maps produced ( Fig.A 2 ) , distinctly exemplifying the transmutation of lowland countries to landfills on the outskirts of Dhaka.\r\nLife-size image ( 292K ) †Opens new window\r\nLife-size image ( 292K )\r\nFig.A 2.A Classified old termlandnext term use/cover maps of Greater Dhaka in 1975, 1992 and 2003.Posit ion Within ArticleThree sectors, namely the populace, private, and individual-household sectors, are responsible for all of the old termlandnext term developments in Dhaka. Most of the old development undertakings were undertaken on an ad hoc soil by the populace sector, chiefly in countries that were antecedently used for agribusiness and that were broad from flood ; illustrations of such developments include Gulshan mould Town, Banani, Uttara Model Town and Dhanmondi ( Chowdhury, 2003 ) . In recent old ages, belongings development has proliferated in Dhaka, and belongings developers have developed both wetlands and agricultural countries without any consideration of the listener environmental costs. In add-on, single families have started to develop the peripheral countries ( Islam, 1996 ) . In the fieldwork conducted in this survey, old termlandnext term guess was observe to hold had a pronounced influence on the development of suburban countries. In response to increase old termlandnext term monetary values and turning requisite for lodging, Lowlandss and agricultural countries in the periphery zone are quickly going built-up by the person and belongings developers. While suburban development is a really Gordian procedure that is known to be influenced by a assortment of factors, including guess and old termlandnext term monetary values, these factors may non adequately explicate the procedure of suburban development in the survey country. A more elaborate survey is hence needful in order to understand the assorted factors act uponing suburban development in the greater Dhaka country. Furthermore, hapless coordination among executive director bureaus is besides responsible for the decrease observed in natural resources in the survey country. For illustration, in the Dhaka-Narayangonj-Demra ( DND ) undertaking, despite about 6000A hr weights being set aside for agricultural production in the 1960s, the country has been used by local and migratory people for residential intents since 1990s without any favourable reception from the governments concerned. Cases such as this illustrate the deficiency of effectual coordination among the organisations involved in the planning and development of Dhaka.\r\nAnalysis of the LULC old termchangesnext term in Dhaka over clip revealed a considerable addition in the built-up countries over the survey period ; built-up countries change magnitude by 6132A minute of arc shift between 1975 and 1992, which is an norm of more than 360A haA yra?’1. Similarly, built-up countries increased in size by 4422A second tiptoe from 1992 to 2003, more than 400A haA yra?’1, and the net addition of old termurbannext term countries over the survey period was 10554A moment topple ( Table 3 ) . When compared with other metropoliss in the part, such as Ajmer City in India, the rate of the old termurban expansionnext term in Ajmer City was 29.2A haA yra?’1 over the period 1977-1989 a nd 32.4A haA yra?’1 from 1989 to 2002 ( Jat, Garg, & A ; Khare, 2008 ) . Although urbanisation is by and large think to demographic old termchangenext term and economic growing ( Li, Sato, & A ; Zhu, 2003 ) , the nature of old termurban expansionnext term in the survey country may besides be associated with other factors such as topography, old termlandnext term usage, and transit. Close scrutiny of the old termchangenext term sensing statistics revealed that about 6132A hour angle of the urbanised country in Dhaka were antecedently either agricultural countries or H2O organic structures between 1975 and 1992. Conversely, 4422A hour angle of the freshly urbanized countries were antecedently flora or wetlands during the same period. By and large, two factors were observed to hold promoted old termurbannext term growing: ( 1 ) increased economic activity associated with the constitution of economic zones ( e.g. export treating zone ) and ( 2 ) redefinition of the met ropolitan country. Between 1975 and 1992, reclassification of old termurbannext term countries every bit good as infrastructural development played a alpha function in the old termexpansion of urbannext term countries. For case, the north-west and southerly old termexpansionnext term of the metropolis occurred in response to building of a inundation embankment in 1992 ( Fig.A 1 ) and a span on the Buriganga River in 2001. The spacial features of built-up countries have besides been shaped by the building of a figure of transit paths in the same period, as still from historical map analysis and field visit. The old termexpansionnext term to the E and neon led to the development of unplanned suburbs in the Lowlandss and agricultural countries that were antecedently located in those countries.\r\nTable 3.\r\nConsequences of old termlandnext term use/previous termlandnext term screen categorization for 1975, 1992 and 2003 images demoing country of each class, category per centum and country changed.\r\nold termLandnext term use/cover types197519921975-1992 country changed ( hour angle )20031992-2003 subject changed ( hour angle )Area ( hour angle )%Area ( hour angle )%Area ( hour angle )%Water organic structures\r\n2976.1\r\n7.2\r\n2492.8\r\n6.0\r\na?’483.3\r\n2050.9\r\n4.9\r\na?’441.9\r\nWetland/lowlands\r\n13155.1\r\n31.7\r\n11646.8\r\n28.0\r\na?’1508.3\r\n9124.0\r\n22.0\r\na?’2522.8\r\n courtly old termlandnext term\r\n12040.8\r\n29.0\r\n7934.3\r\n19.1\r\na?’4106.5\r\n8466.6\r\n20.4\r\n532.3\r\nVegetation\r\n6585.2\r\n15.8\r\n5686.7\r\n13.7\r\na?’898.6\r\n3992.2\r\n9.6\r\na?’1694.4\r\nBuilt-up\r\n5550.5\r\n13.4\r\n11682.4\r\n28.1\r\n6131.9\r\n16104.6\r\n38.7\r\n4422.2\r\n stripped-down soil/landfill\r\n1256.2\r\n3.0\r\n2121.0\r\n5.1\r\n864.8\r\n1825.7\r\n4.4\r\na?’295.4\r\nEntire\r\n41564\r\n100\r\n41564\r\n100\r\n41564\r\n100\r\nFull-size tabular arrayPosition Within ArticleThe GIS analysis besides r evealed that the country meshed by H2O organic structures decreased by 16.2 % , wetlands by 11.5 % , cultivated old termlandnext term by 34.1 % , and flora by 13.6 % between 1975 and 1992. Another important old termchangenext term was the diminution in wetlands and flora from 1992 to 2003. In 1992, wetlands and flora occupied 28 % and 13.7 % of the entire survey country, but by 2003, these countries had declined to 21.7 % and 5.5 % , severally. Conversely, built-up countries increased in size by 37.9 % in the period from 1992 to 2003. A little addition in cultivated old termlandnext term ( 6.7 % ) was besides observed in this period. The diminution of flora and wetlands was intelligibly due to intensification of old termurbannext term development in the greater Dhaka country, peculiarly through the procedure of suburban development. As shown in Table 4, there has been a pronounced old termchangenext term in LULC over the 28-year survey period.\r\nTable 4.\r\nmajor(ip) old termland next term use/cover spiritual rebirths from 1975 to 2003.‘From category ‘‘To category ‘1975-1992 Area ( hour angle )1992-2003 Area ( hour angle )Water organic structures\r\nBuilt-up\r\n655.7\r\n269.5\r\nBare soil/landfill\r\n71.4\r\n82.7\r\nWetland/lowland\r\nBuilt-up\r\n660.0\r\n1414.7\r\nCultivated old termlandnext term\r\n2007.8\r\n2743.6\r\nBare soil/landfill\r\n416.8\r\n492.5\r\nCultivated old termlandnext term\r\nBuilt-up\r\n3944.3\r\n2309.0\r\nBare soil/landfill\r\n794.7\r\n391.8\r\nVegetation\r\nBuilt-up\r\n1725.1\r\n1069.1\r\nCultivated old termlandnext term\r\n932.4\r\n1387.5\r\nBare soil/landfill\r\n333.7\r\n287.3\r\nBare soil/landfill\r\nBuilt-up\r\n453.8\r\n1047.4\r\nFull-size tabular arrayPosition Within ArticleThe post-classification comparing of old termchangenext term sensing was carried out utilizing GIS, bring forthing old termchangenext term maps for understanding the spacial form of old termchangenext term between old ages ( Fig.A 3 ) . Table 4 shows a sum-up of the major LULC transitions, viz. ‘from-to ‘ information, which occurred during the survey period. As testifyd, the bulk of old termurban landnext term was acquired by change overing countries that were antecedently agricultural old termland, following term flora, H2O organic structures or low-lying countries, proposing the being of increased force per unit area on natural resources in Greater Dhaka to run into the increasing demand for old termurban land.next term\r\nLife-size image ( 247K ) †Opens new window\r\nLife-size image ( 247K )\r\nFig.A 3.A major old termlandnext term use/conversions in Greater Dhaka ( a ) 1975-1992 ( B ) 1992-2003.Position Within ArticleThe survey revealed that the old termurban expansionnext term in Dhaka has been comparatively rapid and has resulted in widespread environmental debasement. The procedure of old termurban expansionnext term in Dhaka was observed to change markedly over the old ages examined in th is survey ; specifically, the metropolis expanded by 6131.9A hour angle during the 17-year period from 1975 to 1992 and 4422.2A hour angle in the 11-year period from 1992 to 2003.\r\nLandsat images revealed that old termurban expansionnext term in two periods examined in this survey did non happen equally in all waies ; new developments were observed along the fringe of old termurbannext term countries every bit good as in the countries that had already been urbanized. The rapid gait of urbanisation in Dhaka means that it has non been possible for the municipal authorities to supply basic old termurbannext term comfortss to the population, which has led to a broad scope of environmental jobs. For illustration, old termurbannext term development facilitated by old termlandnext term filling has been shown to hold a negative impact on natural home ground and biodiversity ( [ Alphan, 2003 ] and [ Dewidar, 2002 ] ) . Vulnerability to temblor related jeopardies has besides increased since a major part of Dhaka ‘s recent development has taken topographic point in landfill sites ( Kamal & A ; Midorikawa, 2004 ) . In southern Dhaka, landfills have contributed to dirty pollution, ensuing in trim down flora ( Khatun & A ; Hoque, 1994 ) . Uncoordinated urbanisation and the creative activity of landfill sites have escalate the extent of flood in the metropolis during the moisture season ( Alam & A ; Rabbani, 2007 ) , which is peculiarly critical in the western part of Dhaka ( Maathuis, Mannaerts, & A ; Khan, 1999 ) . Flood portion potency has been upgrade due to continued infilling of H2O organic structures, wetlands and low-lying countries ( Dewan & A ; Yamaguchi, 2008 ) . In add-on, the speed uping growing of slums is impacting the metropolis ‘s physiological and human environment. Harmonizing to CUS etA Al. ( 2006 ) , the slum population of Dhaka ( about 37 % of the metropolis ‘s population ) has three-fold in a decennary , to make 3.4 million in 2006 from 1.5 million in 1996. The environment of these informal colonies is highly unhygienic as they are in close approximation to solid waste mopess, unfastened drains and cloacas, embankments, and along railroad lines ( Islam, 1999 ) . Consequently, the people populating in slums are highly vulnerable to inundations ( Rashid, 2000 ) and they besides birth from an acute deficit of drinkable H2O ( Akbar, Minnery, Horen, & A ; Smith, 2007 ) .Driving forces analysisLULC old termchanges and urban expansionnext term of Greater Dhaka is governed by a combination of geographical, environmental and socio-economic factors. Although population growing is the primary cause for rapid urbanisation, the part of other causes such as economic development and physical factors besides require to be assessed. To measure the mechanisms underlying the old termchangesnext term in LULC and subsequent old termurban enlargement, following term we performed a arrested deve lopment analysis of built-up countries utilizing selected physical and socio-economic variables ( lift, incline, population and gross domestic product ) , and presented the consequences in Table 5. old termUrbannext term country informations were extracted from one-year BBS statistics since RS informations merely cover three old ages. To analyze the effects of incline and lift on old termurban enlargement, following term average values of incline, and lift of both developed and developing countries in the metropolis were metric from a digital lift theoretical account. Socio-economic informations, such as population and gross domestic product values were obtained from the decadal and annually one-year tabular arraies of the Bangladesh Bureau of Statistics ( Table 1 ) .\r\nTable 5.\r\nRegression analysis of factors underlying old termurban expansion.next termDriving factorsCoefficientsRobust criterion mistakeTpA & gt ; A |t| world\r\n1.776\r\n0.633\r\n2.808\r\n0.019\r\ngross dom estic product\r\n0.0001\r\n0.000\r\n4.730\r\n0.001\r\nElevation\r\n0.549\r\n0.295\r\n1.861\r\n0.092\r\nSlope\r\n0.028\r\n0.057\r\n0.494\r\n0.404\r\n unalterable\r\na?’5.058\r\n5.811\r\na?’0.870\r\n0.404\r\nFull-size tabular array\r\nR2A =A 0.947 ; ( ProbA & gt ; A FA =A 0.000 ) ; Dependent variable: Built-up country.Position Within ArticleCensus informations indicate that the old termurbannext term population of Dhaka was merely 0.34 million in 1951, increasing to 2.6 million in 1974 with an one-year growing rate of 9.32 % during 1961-1974 ( Islam, 1999 ) . By 1981, the population had reached 3.44 million. The population reached 6.92 million in 1991 and 10.7 million by 2001 ( BBS, 2001 ) . Presently, the population of Dhaka is more than 12 million with an one-year mean growing of 5 % , compared to the national growing of 2.1 % ( Bangladesh Bureau of Statistics ( BBS ) , 2005 and [ The World Bank, 2007 ] ) . The rapid growing of the old termurbannext term populatio n has chiefly resulted from rural-previous termurbannext term migration and estimates show that more than 60 % of people in Dhaka have migrated from rural countries ( Islam, 1991 ) . Intelligibly, this addition in the population had the consequence of increasing force per unit area on the limited resource-base, and significantly contributed to the old termexpansion of urbannext term countries by glade of natural flora and infilling of low-lying countries. Table 5 clearly shows that old termurban expansionnext term is absolutely related to population growing.\r\nDhaka ‘s economic development is some other factor that has contributed to rapid urbanisation. For illustration, Dhaka ‘s gross domestic merchandise ( gross domestic product ) was about 11,312 million Taka1 in 1976, 129,665 million Taka in 1992 and 162,490 million Taka in 1995. Presently, the GDP of Dhaka is 354,240 million Taka and the metropolis ‘s portion of the national economic system is 19 % ( BBS, 2 005 ) . The economic development associated with the holloa in ready-made garments since the 1980s has had a important impact on old termexpansionnext term of the metropolis country. This economic activity has besides resulted in a big inflow of rural-previous termurbannext term migrators in the same period ( Islam, 1996 ) . In add-on, Dhaka supports more than 40 % of Bangladesh ‘s industry, farther suggesting that the economic development and industrialisation has led to a higher rate of old termurban expansion.next term The arrested development analysis revealed that GDP exercised positive effects on old termurban land expansionnext term ( Table 5 ) .\r\nAs in other old termurbannext term centres, the way of old termurban expansionnext term in Dhaka has been extremely influenced by its physical scene, peculiarly its topography. The four major rivers, swamps and depressions within and around the metropolis have ever played a polar function in the development of built-up coun tries in the metropolis. urbanization ab initio occurred in the elevated countries that were non change by inundation. Once all the elevated places had been developed, the lifting demand of old termurban landnext term has been met by the transmutation of low-lying countries, vegetated countries and wetlands. The development of wetlands, for case, has led to a significant loss of natural resources and an addition in habitat debasement. The growing of belongings developers has accelerated invasion of old termurbannext term countries on wetlands and threatens biodiversity. Two geophysical indexs were used in the arrested development analysis ( Table 5 ) and found that lift has major influence on old termurban expansionnext term while incline has non passed the important trial.DecisionsThis survey has assessed LULC old termchangesnext term and the kineticss of old termurban expansionnext term in Greater Dhaka, Bangladesh utilizing RS informations in concurrence with socio-economic var iables. old termUrban expansionnext term was quantified for the last 28 old ages utilizing the post-classification comparing technique. Greater Dhaka was found to hold experienced rapid old termchangesnext term in LULC, peculiarly in built-up/previous termurbannext term countries. Analysis revealed that old termurbannext term countries increased by 6131A hour angle during 1975-1992 and 4422A hour angle from 1992 to 2003, which resulted in a significant decrease in the country of H2O organic structures, flora, cultivated countries and wetlands/lowland. The dramatic old termexpansion of the urbannext term countries of Dhaka exhibited clear spatio-temporal differences. The transition of H2O organic structures, flora and low-lying countries to old termurban landnext term has caused extended and varied environmental debasement in the survey country, and the exposure to implosion therapy and the growing of slums have been the chief negative results associated with the rapid old termurbann ext term development. old termUrban land expansionnext term has been mostly driven by lift, population growing and economic development.\r\nIntegrated usage of GIS, RS and socio-economic informations could therefore be efficaciously used to understand the spatial and temporal kineticss of LULC old termchanges.next term The reading and categorization of RS informations were utile for gauging the rate and spacial form of the old termurban expansionnext term in Greater Dhaka of Bangladesh. As dependable and current informations are missing for Bangladesh, the old termlandnext term usage maps produced in this survey will lend to both the development of sustainable old termurban landnext term usage planning determinations and besides for calculating possible hereafter old termchangesnext term in growing forms.\r\n'