Ngyyen Kim Loi Watershed and Environmental Management, Nong Lam University (NLU), Ho Chi Minh City, VIETNAM

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1 Decisio Support System (DSS) for Sustaiable Watershed Maagemet i Dog Nai Watershed, Vietam: Coceptual Framework ad Proposed Research Techiques Ngyye Kim Loi Watershed ad Evirometal Maagemet, Nog Lam Uiversity (NLU), Ho Chi Mih City, VIETNAM Abstract: Decisio makers today eed to be able to rapidly fid good solutios to icreasigly complex problems. Optimizatio based o decisio support system (DSS) ca help decisio makers to meet this challege. Buildig such systems, however, is expesive ad time cosumig.the use of decisio support system (DSS), liear programmig (LP), ad geographic iformatio system (GIS) for sustaiable watershed maagemet i Dog Nai watershed is preseted. A geeral statemet of system requiremet for DSS has bee coceptualized to provide a set of core requiremet ad behavior for DSS for mutil-criteria decisio makig i sustaiable watershed maagemet. Classes of decisio elemets for the aalysis of decisio problems ad of other DSS compoets are idetified. This paper ivestigated also how demographic (socioecoomic) ad -use (physical ad evirometal) data ca be itegrated withi a multi-scaled decisio support system framework to formulate ad evaluate -use plaig scearios. A case study approach is udertake usig what-if plaig scearios for a Dog Nai Watershed, Vietam. This paper has ot oly briefly outlied the three future use scearios comprised withi the framework but also has geerally methodology i developig decisio support system (DSS) for sustaiable use allocatio. Sceario A - Future tred sceario is based o existig socio-ecoomic treds. Sceario B Maximizatio allocatio sceario will be derived usig maximizig modellig of valuatio data. Sceario C Sustaiable Developmet will be derived usig a umber of evirometal layers ad assigig weightigs of importace to each layer usig a multiple criteria aalysis (MCA) approach. The what-if plaig scearios was expected through the use of maps ad tables withi a geographical iformatio system (GIS), which delieate future possible -use locatio - allocatios. Each of the scearios ad their uderlyig model will be applied to the Dog Nai watershed, Vietam. Keywords: Decisio support system (DSS); Sustaiable watershed maagemet, Dog Nai Watershed, Vietam 1. INTRODUCTION Degradatio of watershed is a commo pheomeo aroud the world. There are several reasos for such degradatio, but most importat is improper utilizatio of watershed resources, amog which use allocatio is the most importat. Lad use allocatio have affected watershed ad degradatio. The most importat cosequece of degradatio i Vietam is the loss of productivity, depletio of faua ad flora ad reductio of agricultural per capita. I terms of the estimated moetary loss o accout of degradatio, water erosio ad leachig accouted for more tha half, saliisatio, acidificatio, drought ad water loggig for about oe third ad declie i soil fertility for the rest. (Buckto. et. al. 1999). The cosequeces of flood iudatio ad water loggig are very serious o humas ad precious atural resources. For example, two floods i 1999 occurred i the souther cetral coast claimed 711 lives ad caused ecoomic loss estimated at more tha US$ 235 millio. Besides, millios of tos of soil from the hilly ad moutaious regios was eroded ad flowed ito rivers, streams, plais ad the sea. I Dog Nai watershed, large forest area has bee replaced by the expasio of agricultural area, for food subsistece ad the, for cash crop (*)

2 productio, especially sice the begiig of the "ope ecoomy" i 1980s. Traditioal maagemet systems for forest, ad water have bee replaced by subsidiary state-ru eterprises ad agecies, which were ot well motivated to eforce formal regulatios ad to stop the tred of becomig a ope-access situatio. I reality, use chages ad forest resource depletio i Vietam's up ecosystems have bee occurred with alarmig rates. The up has bee a place suffered a rapid icrease i populatio, resultig of massive immigratios sice the ed of the war i I the begiig, poor less farmers from desely populated provices came to the up to seek for livelihoods alteratives uder atioal programs as the creatio of ew ecoomic zoes (NEZ), or to work as hired labors i state-ru forestry ad agriculture eterprises. Hece, this research attempts to solve the selected Dog Nai watershed i cotext of watershed maagemet through the Liear Programmig ad GIS criteria-dss (Decisio Support Systems) approach. 2. OBJECTIVES I order to formulate watershed maagemet pla i Dog Nai watershed, the mai aim i this ivestigatio is how to apply LP ad GIS criteria- DSS (Decisio Support Systems) for optimizig use allocatio ad relocatig the solutio i Dog Nai watershed. The specific objectives of this study are as follows: 1/ to assess use/ cover chage i Dog Nai watershed durig the period from 1990 to 2000; 2/ to determie the decisio variable coefficiets for LP ad GIS; 3/ to apply LP techique for optimizig use allocatio i Dog Nai watershed uder the criteria of multiple objectives, limited resources, ad permissible impacts to the water yield; 4/ to apply GIS ad DSS techiques for relocatig mappig the optimized use allocated by LP i Dog Nai watershed. This paper aims at presetig geeral methodology i developig DSS for sustaiable allocatio i Dog Nai watershed, Vietam. 3. RESEARCH METHODOLOGY AND MATERIALS The mathematical programmig techiques amely Liear Programmig (LP), MINMAX formulatios were employed to rakig the desirable priorities, their potetial outcomes, ad quatifyig their achievemet level respectively. Liear programmig makes it possible to obtai the optimal solutio of the problem i order to make the objective fuctio maximum or miimum while fulfillig all other requiremets at the same time. Liear programmig is able to give a sythetic approach to complex situatios. The results ad problem structure are discussed i the ext sectio, before that a out look of the ecessity for itegratig the GIS alog with aalytical model has bee elaborated i the followig sectio. The methodology employed herei ca be described as follows: Study Area Descriptio Dog Nai watershed locates i the Souther of Vietam which is oe of three provice at East Souther, Vietam. It is situated betwee latitude ad logitude. The regio occupies a area of approximately 586,427 ha.the Dog Nai watershed locates maily i Dog Nai provice ad a smaller part i Lam Dog provice. Three forms of topographical formatios ca be idetified i the area: a moutaious area i the orth, a basaltic plateau i the south, ad betwee them is a trasitio zoe of alluvial valleys. The average elevatio is about 500 m asl. The topography of its major part i the North is oly slightly udulated with a slope of less tha 8 o, resulted from the layers of basaltic depositio while high slopes are foud i the Northeaster moutaious part ear the border with Lam Dog provice. 3.1 MATERIALS The ecessary materials for this ivestigatio were set up for the purpose of secodary data of socioecoomic withi ad outside of the study area were also take ito accout. The materials are as follows: 1. Topographic map scale 1 : 50, Persoal computer ad LIDO 6.0 software (Liear, Iteractive, ad Discrete, Optimizer) for quatifyig the solutio (Schrage, 1999). 3. GIS software (AcrView 3.2a, Arc Ifo 3.5). 3.2 METHODS Data Collectio Available data ad iformatio related to the decisio support systems (DSS) for sustaiable watershed maagemet i Dog Nai watershed such as maps, statistic data, forest area, forest cover, populatio, icome, soil erosio parameter, precipitatio, sedimet ad other the related data will be collected by the offices of local authorities ad relevat professioal istitutios. The Sceario plaig methodology

3 The sceario plaig approach applied to the case study area of Dog Nai watershed. The pricipal plaig task is to brig about the efficiet plaig of future i Dog Nai watershed. The objectives from each of these plas assist i decidig upo the socio-ecoomic, physical ad evirometal data required to formulate the differet plaig scearios. The objectives are also used later i the methodology to evaluate the efficiecy of each proposed plaig sceario. A umber of socio-ecoomic, physical ad evirometal data iputs are required to drive the -use plaig scearios. Core socioecoomic data iputs iclude: populatio, birth rate, death rate, immigratio rate, ad emigratio rate. Core physical ad evirometal data iputs iclude: water flow, -use (forest, agricultural, special, ope ), ad urba), soil erosio. The ext step of the methodology is to formulate possible -use scearios. Three -use plaig scearios are formulated for Dog Nai watershed. Sceario A - future treds is based o existig socioecoomic treds. Sceario B Optimizatio allocatio will be derived usig optimizatio modellig of valuatio data. Sceario C sustaiable developmet will be derived usig a umber of evirometal layers ad assigig weightigs of importace to each layer usig a multiple criteria aalysis (MCA) approach. As previously metioed the evaluatio of each of the three -use scearios is udertake usig the core plaig strategies. The objectives ad policies cotaied withi these strategies are used i evaluatig the efficiecy of each proposed use sceario, through the use of a goals achievemet matrix (GAM). The process of evaluatio is cosidered iterative i that the results foud through prelimiary evaluatio of the scearios ca lead to the re-workig of a sceario. The ed result of the sceario plaig approach is the formulatio of a fial pla, to be reviewed accordigly. The Plaig Scearios for Dog Nai watershed Future Tred Sceario (A) The future tred sceario makes predictios of -use chage based upo existig socioecoomic treds. This sceario approach will apply to the case study area of Dog Nai watershed. use chage based o the use evolutio betwee (1)Forest (2)agricu lture (3)Urba (4)Ope (5)Speci al two give periods. The geeral form of the model to predict use chage from 1 st date (year) to the 2 d date (year) is expressed herei as: Proportio of use of the first date LUCC 1 st time LUCC 2 d time Where ij : is probability of chage determied from overlayig of two differet periods of use map. The predictio of the ext (forward ad backward) period of use distributio ca be expressed as: This ca be trasformed (backward) i geeral matrix multiplicatio as: * Matrix of probab ility of = (1)Forest (2)Agricult ure (3)Urba (4)Ope (5)Special Proport io of LUCC 2 d date Models for predictig aual -use chages I order to obtai year-by-year use chages, the Markov Chai model. The Markov Chai model was applied to determie probability of [V 1, V 2,..., V 5 ] 1 * 11, 12, 13, , 22, 23, = [V 1,.., V 5 ] 2

4 Optimizatio Lad Allocatio Sceario (B) The objective of this sceario is to establish the optimal -allocatio for each of the competig -uses withi the Dog Nai watershed. The sceario utilises liear programmig, based upo a similar methodology put forth by Chuvieco (1993), which itegrates liear programmig ad GIS for -use modellig. The result of the liear programmig is a optimal allocatio for each of the -use categories withi Dog Nai watershed, based upo the costraits put forth i the model which iclude: evirometal protectio, existig agricultural, miimum ope space, ad maximum available water supply. Similarly to Sceario A, trasitio rules ad a use/ compatibility matrix have bee used to decide the most suitable locatio of the projected demad with respect to supply i Dog Nai watershed. Similarly to Sceario A, trasitio rules ad a use/compatibility matrix have bee used to decide the most suitable locatio of the Dog Nai watershed. Accordig to the liear programmig (LP) problems, it ca be wrote dow i geeral form as follow: MiimizeZ = Subject to MaximizeZ = Subject to Where j= 1 j=1 cjxj aijxj bi X j >= 0 j=1 j= 1 cjxj aijxj bi X j >= 0 i = 1,2,3,, j = 1,2,3,., i = 1,2,3,, j = 1,2,3,., Z = total amout of costs or beefits from certai activities of the objective fuctio; X j = level or uit of productio activity j c j = cost or et beefit to uit of productio activity j a ij = the amout of productio i used for productio activity j b i = the amout of costrait productio iput i Sustaiable Developmet Sceario (C) This sceario focuses upo the pricipal of evirometally sustaiable developmet ad takes ito accout areas of both evirometal ad ecoomic sigificace ad allows trade-offs to occur betwee these sometimes-coflictig areas.the techique allows the user to assig various weightigs of importace to differet use factors ad examie the results both i report ad map form. Evirometal layers icludig; remat vegetatio, riparia vegetatio, atioal parks, state forests, coastal wets, ad good quality agricultural are assiged appropriate weightigs of importace i order to produce suitability reports ad maps. LITERATURE CITED Chuvieco., E Itegratio of liear programmig ad GIS for -use modelig. IJGIS, Vol. 7, Coho, J.L Multiobjective Programmig ad Plaig. New York: Academic Press. Datzig, G. B., 1963: Liear programmig ad Extesios (Priceto Uiversity press). Dog Nai Statistical Departmet Statistical Yearbook. MARD. Vietam. (i Vietamese).190p. Departmet of Agriculture ad Rural Developmet i Dog Nai Report of Lad use i Dog Nai from MARD. Vietam. 50p.(i Vietamese). Departmet of Lad Developmet Report of Lad use i Dog Nai i MARD.Vietam. 20p. (i Vietamese). Dueker, K.J., 1987: Geographical iformatio systems ad computer aided mappig. Joural of the America Plaig Associatio, 53, Dykstra, D.P., 1983: Mathematical programmig for Natural Resources Maagemet (New York: McGraw hill). Haith, D.A Evirometal Systems Optimizatio. Joh Wiley & Sos, Ic., New York, U.S.A. 306 p. Huggett.R.J Modellig the Huma Impact o Nature: System Aalysis of Evirometal Problems. Oxford Uiv. Press. Oxford. 205p. Hwag, C.L. ad K. Yoo "Multiple attribute decisio makig, methods ad applicatios", Lecture Notes i Ecoomics ad Mathematical Systems, V.186. New York: Spriger-Verlag. Levi, R.I., C.A. Kirkpatrick ad D.S. Rubi Quatitative Approaches to Maagemet. 5 th ed., School of Busiess Admiistrastio, Uiversity of North Carolia at Chapel Hil. Mc-

5 Graw Hill Book Compay, Auck. 763 p. Liu, Y A model of DSE: Decisio support eviromet for egieerig use, to be published i Hydrosoft 94, Proceedigs of the 5th Iteratioal Coferece o Hydraulic Egieerig Software, Porto Carras, Greece. Maguire,D.I., 1991: A overview ad defiitios of GIS. I Geographical Iformatio systems edited by D.J. Maguire, M.F. Goodchild ad D.W. Rhid (Lodo: Logma), Maidmet, D. R. (1993) GIS ad hydrologic modelig. i Evirometal Modelig with GIS, Goodchild, M. F., B. O. Parks, ad L. T. Steyaert (ed.) Oxford Uiversity Press, New York.Opeshaw, S., 1991: Developig appropriate spatial aalysis method for GIS.I Geographical Iformatio systems. Edited by D.J. Maguire, M.F. Goodchild ad D.W. Rhid (Lodo: Logma), Power, D.J Decisio support systems glossary. DSS resources, World Wide Web Power, D.J What is a DSS? Dsstar Thw Olie Exec. Joural for Data- Itesive Decisio Support, 21 October 1(3). Simoovic, S. P Decisio support for sustaiable water resources developmet, i Water Resources Plaig i a Chagig World, pp. III- 3 to III-13, Proceedigs of the Iteratioal UNESCO Symposium, Karlsruhe, Germay.