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DECISION SUPPORT MODEL FOR INTEGRATED WATER RESOURCES MANAGEMENT: A CASE STUDY FOR THE THA CHIN RIVER, THAILAND
SUKANDA LEKPHET1, PAWEENA PANICHAYAPICHET2, NARES CHUERSUWAN3, WIJARN SIMACHAYA4, and APAITHOON SUWANCHOOJIT1
1 Bureau of Research-Development and Hydrology, Department of Water Resources,
3/12 U-Thongnok Rd.,Dusit, Bangkok,Thailand.
2 The JointGraduateSchool of Energy and Environment, King Mongkut’s University of
Technology Thonburi, 91 Pracha-Uthit Rd.,Thugkru, Bangkok, Thailand.
3 School of Environmental Health, Institute of Medicine, SuranareeUniversity of
Technology, 111 University Avenue, Muang District, Nakhon Ratchasima, Thailand.
4 Water Quality Management Bureau, Pollution Control Department, 92 Phahonyothin
Rd., Phayathai, Bangkok,Thailand.
The stress on water resources is continuously increasing in Thailand and managing water resources in a sustainable approach is a challenging mission. Over a decade, population growth, land use changing, urbanization, intense agriculture, farming, and industrialization have produced substantial changes in the ThaChinRiver, an important river in central Thailand. The problems include water quality degradation, toxic dumping, and saltwater intrusion, leading to conflicts and confrontations among various water user sectors. Thus, logical and effective conflict resolutions of water usage and wastewater discharge allocation are now instantly needed to ensure the sustainable use of water resources. To resolve the conflict, all stakeholders are participated in establishing the action plan and involved in activities to restore and implement the integrated management of the ThaChinRiver basin. This project provides a comprehensive tool in supporting the decision-making processes by generating practical resolution to water quality problems for the basin. The tool consists of the ArcGIS, Water Quality Analysis Simulation Program (WASP),and stakeholders analysis module that based upon spreadsheet and database software. The decision support model output, then, provides to all stakeholders for creating action plan in integrated management of water resources. This paper will address the water quality problems focusing on the development of the prototypedecision support system for the lower portion of the ThaChinRiver basin.
INTRODUCTION
The ThaChinRiver basin is located in the central Thailand. The basin covers 13,682km2 and has population of around 2.6 million. The main channel of the ThaChinRiver is 320 km in length and flows through four provincesand discharging directly to theGulf of Thailand. Thisriver has been subdivided into three sections: lower, middle, and upper based on the national surface water quality standard and its classification.Over a decade, population growth, land use changing, urbanization, intense agriculture, farming and industrialization have produced substantial changes in the Tha-chinRiver basin. The problems include water quality degradation, toxic dumping, and saltwater intrusion, leading to conflicts and confrontations among various water user sectors. According to the year 2002 State of the Environment Report [1], the ThaChinRiver, in the lower partfrom Nakorn Chaisri District of Nakorn Pratom Province to estuary in SamutSakornProvince, was heavily polluted and the water quality was very much below the standard level set for surface water quality, especially dissolved oxygen. The main sources of pollution are point sources originating from domestic, swine farm and industrial effluent, and non-point pollution generated by human activities, such as paddy fields, orchards, and urban runoff. Despite repeated efforts at rehabilitation and management,the lower portion of the ThaChinRiver and its surrounding area have remained extremely polluted for decades.
In view of these situations,logical and effective conflict resolutions of water usage and wastewater discharge allocation are now instantly needed to ensure the sustainableuse of water resources.For the ThaChinRiver, waste load allocations are being considered depending on assimilative capacity of receiving water body and guidelines to attain receiving water quality standard. Based on the concept of integrated water resources management, the participations of all stakeholders are necessary to establish the action plan for remediationas well as the involving in activities to restore and implement the integrated management of the Tha-ChinRiver basin.
This paper was a part of research project that aimed toprovide a comprehensive tool in supporting the decision-making processes by generating practical resolution to water quality problems for the basin. The development of aprototype DSS for water quality management in theLower Tha Chin River (LTC_DSS) was elaborated. The participatory process of developing the prototype LTC_DSS and construction of the GIS database providedbetter understanding of proper water quality managementto the stakeholders.The prototype DSS output, then, was used for creating action plan in integrated management of water resources by all stakeholders.
THE LTC_DSS DESIGN
DSS isa useful computer tools for support problem solving and decision making. The prototype LTC_DSS was designed to facilitate the evaluation of alternative measures for decision makers as well as stakeholders. Objectives for developing a prototype LTC_DSS were to provide a set of analytical tools that assisted in the estimation of load contributionsand the selection of the optimum alternatives for water quality management in the LowerThaChinRiver basin.The prototype LTC_DSS can be an important tool to:
- increase the understanding of the users, all stakeholders, in the water quality dilemma of their water resources;
- integrate monitoring water quality data and interpret the results; and
- provide a user-friendly framework and compare water quality management measures.
The prototype LTC_DSS included the following tools: ArcGis (ESRI), Water Quality Analysis Simulation Program (WASP), and stakeholder analysis module that based upon spreadsheet and database software (see Figure 1).
Data
Process and tool
Output
Figure 1. Schematic of the Prototype LTC_DSS
The application of the prototype LTC_DSS and accompanying data collection and analysis hadpreviously led to an imposing update on many facts and figures of the lower portion of the Tha Chin River basin such as total waste loads from the different sectors and areas, water quality situation and various attitudes of all stakeholders. These new data had improved the credibility of the prototype LTC_DSS.
STAKEHOLDERS ANALYSIS
In order to ensure the sustainable use of water resources, integrated water resources management (IWRM) stresses theimportance of involving all stakeholders within the basin. Based on this principle, in the study, the selection of optimum measure must be a balance between the acceptance of stakeholders and good water quality. The general approach was to have all stakeholders determine relative priority of pollutant sources by using a ranking method [2]. Organized local workshops attended by all stakeholders: sub-committees of the ThaChinRiver basin, local governmental units, local communities, NGOs, local academics, civil society groups, farmers, swine farms and industrial representatives as wellas the issue regarding to gender. All stakeholders of about 50 peoples were invited and asked to rank the pollutant sources that must be reduced their loading. The ranking order was 1 to 5, based upon the most significant source to the least significance.
The results of the stakeholder analysis were given in Table 1. All participants believed that reduction of waste from industrial sectorswas the most importancefollowed by domestic, and all point sources (combined domestic, industrial sectors, and swine farms). The reduction of waste from domestic and swine farms ranked last. This stakeholder analysis was employed insetting up scenarios in themodel.
Table 1.Ranking and priority of sources for waste load reduction
Pollutant sources / Rank averagereduction of waste from industry / 1.94
reduction of waste from domestic / 3.03
reduction of waste from domestic, industry and swine farms / 3.09
reduction of waste from swine farms / 3.14
reduction of waste from domestic, industry, swine farms, and using fertilizer and pesticides from agricultural area / 3.18
reduction of the using fertilizer and pesticides from agricultural area / 3.57
reduction of waste from domestic and swine farms / 3.75
WATER QUALITY MODEL
The computer program applied to the water quality analysis of prototype LTC_DSS was WASP, which has been modified by US Environmental Protection Agency [3]. The lower portion of theThaChinRiver was divided into 22 waterbody segments (see Figure 2)and the model was ran on the steady state condition.
Input data
Input data for WASP included parameterization, time step, segmentation, flow, dispersion, boundaries, loads, environmental parameters, and kinetic constants. Water quality data obtained from the sampling stations of the Pollution Control Department (PCD) (see Figure 2). Loading data were separated into point and non-point sources. Pollutant loadings from point sources were calculated from population statistics, swine farms, and industrial discharges.Loadings from non-point sourceswere calculated through integrating topographic data, land use, and runoff concentration using raster data of the basin. The structure of pollution load was illustrated in Figure 3.
Point Sources Pollution
Pollutant loadings from domestic were generated by the communities in the basin. The wastewater discharges were estimated from the number of population in the area. Based on studies in Thailand, pollution loadings in terms of BOD, NH3-N, NO3-N have been derived and further projected to 2012. The pollutant loadings were presented on a daily average per capita (Table 2).
Figure 3. Structure of total pollution load used in the prototype LTC_DSS
Swine farms were a major potential source of pollution because they generated high concentration of organic matter. The loadings per head for swine were estimated based on daily average as given in Table 2.The BOD concentration of the industrial wastewater in the basin was taken from the minimum permitted concentrations while NH3-N and NO3-N values were taken from Simachaya [4] (Table 2). Discharge rates from the factories were unavailable, thus, this study used other country data which was about 0.025 gallons per square foot/day [5] and industrial areas were estimated from the GIS landuse map. Industrial wastewater loadings were calculated from multiplying industrial landuse area by pollutant loadings. Future loadings were derived from the population (1.5%) swine production (2.75%) and industrial production growth rates (3%).
Table 2. Point sources loading in the LowerThaChinRiver Basin
Pollutant / Domestic (g/ca/day) / Swine / IndustryUrban / Rural / (g/head/day) / (mg/L)
BOD / 35 / 25 / 20 / 20
NH3-N / 7.0 / 5.0 / 6 / 0.5
NO3-N / 0.15 / 0.15 / 1.8 / 0.2
Source: Simachaya (1999)
Non-PointSources Pollution
Non-point sources were generated through the hydrological cycle (the runoff from rainstorms). The runoff washed the pollutants from wide diffuse areas and transported to the watercourses. Landuse covered the areas of urban, agriculture, forest, industry, recreation and golf course, and water body. Non-point source loadings were estimated on unit area basis using average runoff pollutant concentration (Table3) and discharges were estimated from the relationship of rainfall and runoff as described in Simachaya [4].The distribution of non-point source loadings (kg/d/grid cell) in the LowerThaChinRiver basin was illustrated in Figure 4.
Table 3.Estimated runoff concentration
Land Use / BOD (mg/L) / NH3-N (mg/L) / NO3-N (mg/L)Urban / 15.0 / 0.50 / 0.20
Agriculture / 2.7 / 0.32 / 0.01
Forest / 1.5 / 0.05 / 0.01
Industry / 20.0 / 0.50 / 0.20
Recreation and golf course / 1.5 / 0.30 / 0.20
Water body / 1.6 / 0.10 / 0.20
Source: Simachaya (1999)
Model run
Dissolved oxygen (DO) is considered as the most important factor for water quality management in the Lower Tha Chin. Thus, themodelwassimulated under average annual flow to compare the effect of waste load from various scenarios on DO concentration. Scenarios were based upon the result of stakeholder analysis and existing action plans for water quality improvement. There were two “base case” scenarios, no.1 and 2, that represented loading projections for the years 2002 and 2012. Goals for simulating water quality were to maintain the national water quality standards of the Lower Tha Chin, specifically DO (not less than 2.0 mg/L). Table 4 showed the scenarios developed in this study. The predicted DO concentrations from several scenarios were shown in Figure 5. The model results of each scenario were examined by scoring the DO concentration. The scores were given as 1 for acceptable water quality level (DOnot less than 2.0 mg/L) for each river segments. The highest score for water quality was the scenario 5 and 7. However, none of the scenarios ensuredthe achievement of the necessary DO levels for all waterbody segments within the LowerThaChinRiver.
Table 4. Water quality management scenarios for the LowerThaChinRiver basin
ScenarioNo. / Description / Score1 / “Do Nothing”, existing treatment facility included, 2002 data, incorporating both point and non-point loads projected / 0
2 / As scenario 1 but incorporating loads projected for 2012 / 0
3 / 70 % industrial waste reduction / 6
4 / 70 % domestic waste reduction / 0
5 / 70 % waste reduction from industry, domestic, and swine farm / 11
6 / 70 % swine farm waste reduction / 0
7 / 70% reduction of waste from domestic, industry, swine farms, and using fertilizer and pesticides from agricultural area / 11
Figure 5. DO predictions for various water quality scenarios
CONCLUSIONS
Results from WASP and stakeholder analysis module indicated thattwo alternatives could be partially achieved the national surface water quality standard. The first alternative was 70% reduction of wastewater loadings from domestic, industry and swine farm.The second was similar to the first alternative, but it further required the reduction of fertilizer and pesticide usage in the agricultural area (the waste loadings from agricultural non-point sources was approximately 1% of the total loading). Information from the model can be used to develop an action plan for water resources management for the LowerThaChinRiver Basin and helped prioritizedthe management action to obtain the optimum achievement of the river water quality.
The application of the prototype LTC_DSS provided a useful tool to support therehabilitation planning and assistedthe decision-makers and all stakeholders understanding. The process of developing the prototype LTC_DSSallowed problem-based learning and can be used for exploratory scenario analysis including promoted novel solutions to the problem. While the LowerThaChinRiver remains severely polluted, plans for rehabilitation and management of the system are progressing on the several fronts. By incorporating stakeholders opinion and participation along with decision-makers policy as modules in the DSS, the prototype LTC_DSS demonstrated a practical tool in integrated management of the water resources for sustainable development in the ThaChinRiver basin.
ACKNOWLEDGEMENTS
The authors wish to acknowledge the Water Quality Management Bureau, Pollution Control Department for supporting the data and to all stakeholders in the ThaChinRiver.
REFERENCES
[1]Office of Natural Resources and Environmental Policy and Planning,“Thailand State of the Environmental Report 2002: Executive Summary”, 1st edition, Ministry of Natural Resources and Environment, Bangkok, (2002).
[2]Cushman, W.H., Rosenberg, D.J., “Human factors in product design”, 1st edition, Elsevier, Amsterdam, (1991).
[3]Wool, T.A., Ambrose, R.B., Martin, J.L., Comer, E.A. “Water Quality Analysis Simulation Program (WASP) Version 6.0: Draft User’s Manual”, US Environmental Protection Agency-Region 4, Atlanta, GA, (2003).
[4]Simachaya, W. “Integrated Approaches to Water Quality Management Using Geographic Information Systems and The WASP5 Simulation Model: Application to the Tha Chin River Basin, Thailand”, Ph.D. Thesis, The University of Guelph. (1999).
[5]Water/Wastewater Department, “Guidelines for Estimating Wastewater Flow from Commercial, Industrial, and Institutional Users” City of Colton. CA,US. Retrieved April5,2004, from Building/fees-