5.7 Porsuk River Basin Turkey

5.7 Porsuk River Basin Turkey A. Tanik, M. Gurel, and I.E. Gonenc 5.7 Porsuk River Basin--Turkey 5.7.1 Introduction 5.7.2 Description of the Physical Domain 5.7.3 Description of Data Collected 5.7.3.1 Water Quality and Related Regulations 5.7.4 Brief Description of the Models Used 5.7.5 Calibration of Models 5.7.6 Discussion of Modeling Results 5.7.7 Conclusions and Recommendations References 5.7.1 Introduction One of the projects carried out in Turkey within the context of the NATO Science for Stability Program was entitled River Basin Management for the Sakarya Basin. Its goal was to realize the application of water resource systems planning techniques developed in theory to a real planning study in Turkey by choosing the most cost-effective development plan for the basin. Efforts were made to plan the optimal design and operation of river basin resources, focusing on beneficial uses such as water supply, irrigation, hydropower, flood control, navigation, recreation, etc. The project was conducted by the Civil Engineering Faculty of Istanbul Technical University (ITU), with the cooperation of the General Directorate of State Water Works (SWW) and participation of the Operations Research Department of the Marmara Scientific and Industrial Research Institute (MRI). This was the first Project conducted in river basin management in the country. It involved a multi-disciplinary group of university, governmental and industrial institutions that developed an optimal design and operations plan for the Basin s multi-unit, multi-purpose water resource systems, including almost all water quality aspects. A systems approach was adopted as the major tool to develop this multipurpose, multiunit water resources plan. Project work was carried-out in many phases, with the planning phase taking almost a year. The actual studies began in July 1981 and terminated at the end of 1988. It was planned to complete the Project within a period of five years; however, the project period was extended due to unexpected difficulties (Project Report 1989). After completing the collection and evaluation of available data and review of existing development projects, the river basin model set-up began. It was decided to divide the Sakarya River Basin into subsystems to be analyzed separately. Various subsystems were then considered in the planning analysis of the river Basin in an integrated manner. This mathematical model of the whole Basin was to form the basis for the preparation of the river basin management plan, in which environmental quality would be a major consideration. As seen in Figure 5.7.1, the developed mathematical model of the Sakarya River Basin consisted of the models for the subsystems; namely, the Porsuk River Basin, Ankara River Basin, Upper Sakarya Basin, Middle Sakarya Basin, and Lower Sakarya Basin, plus the Water Quality Management model for the whole Basin. 1

In the current Pilot Study, the Porsuk River Basin subsystem analysis was selected for presentation; this specific river is one in Turkey where many modeling studies have been carried out over many years up to the present. Within this general context, the basic framework of the water quality management model for the Sakarya River Basin, identifying all essential elements and interactions, was developed as given in Figure 5.7.2 (Gonenc et al. 1989). The MODQUAL water quality model (Postma 1981), which is a modification of the QUAL II model (Roesner et al. 1977), was originally selected as an appropriate tool to characterize the Porsuk River. The river model was reevaluated and calibrated using the latest version of QUAL2E in 1990 (Baltaoglu 1990). Kefli (1994) performed uncertainty analysis with the QUAL2E-UNCAS program and the calibrated Porsuk River Model. Possible improvements of water quality characteristics under various management scenario options were recently investigated by means of mathematical models utilized in an integrated manner. The assessment model choices were QUAL2E (Linfield and Barnwell 1987) for the river and BATHTUB (Walker 1999) for the Porsuk Dam Reservoir. These model results for the Porsuk River indicated a hypertrophic state (Muhammetoglu et al. 2002). All the referenced modeling studies and the outcomes of the model applications will be described in the following sections. PORSUK RIVER BASIN UPPER SAKARYA BASIN ANKARA RIVER BASIN MIDDLE SAKARYA BASIN WATER QUALITY MODEL LOWER SAKARYA BASIN Figure 5.7.1 Diagram of the mathematical model of the study (Project Report 1989) 2

BENEFICIAL USE PLANNING Land Use Water Use RIVER BODY Quality Parameters/ Processes (State Variables) Modeling Waste Allocation Water Quality Monitoring BENEFICIAL USES Consumption Recreation Fishing Irrigation Navigation Energy Production Treatment Requirements POLLUTION SOURCE Waste Characterization Waste Categorization Pollution Profile Source Priority Quality Regulations Figure 5.7.2 Conceptual approach to water quality management in the Sakarya River Basin (Gonenc et al. 1989) 5.7.2 Description of the Physical Domain A map of the study area is provided in Figure 5.7.3. Turkey is a country with considerable water resources potential. Average annual volume of flow in Turkish Rivers is about 186.5 million m 3, approximately 0.5% of the total river flow volume of the world (Project Report 1989). Water resources development activities have greatly accelerated during the past two decades due to rapid population increase and industrialization. The Sakarya River, as an example, serves as a resource for utilities like hydropower, water supply, irrigation, flood control, and navigation. It is one of the major rivers of Turkey, draining to the Black Sea, with a total catchment area of 58 000 km 2, approximately 7% of Turkey's area. Its average annual flow volume is about 6 million m 3, 3.3 % of that of all rivers in the country. The Basin has a rectangular shape with the axis in the west-east direction. The two major tributaries of the Sakarya River are the Porsuk River and Ankara Stream that join near the center of the basin. Most of the basin has a typical continental climate, with hot and dry summers and cold and semi-humid winters. The northern part is more humid and has a temperate climate. The average annual precipitation for the whole basin is approximately 500 mm, slightly lower than the annual average of the country. A substantial part of the precipitation occurs in the form of snow in the mountainous parts of the basin. The number of major sampling stations still in operation is 21. Only 2 stations have records of more than 50 3

years, but another 10 have more than 35 years. The average discharge of the Sakarya River near its mouth equals 187 m 3 sec -1. Flows are controlled by the operation of the Sariyar Reservoir (under operation since 1956) and Gökçekaya Reservoir (under operation since 1973). The major lake in the basin, Sapanca Lake, has a state monitoring station. The basin has a rather varied geological and topographical structure. Almost all the geological periods are found among the various parts of the Basin. The northern and western parts of the basin are seismologically active. The number of inhabitants in the basin exceeds 5 million, about 10% of Turkey's population (Project Report 1989). The cities of Ankara, Eskişehir and Adapazari rank among the major centers of industry in the country. Figure 5.7.3 Location of Sakarya River Basin in Turkey Most of the population in the Basin is employed in agriculture. Inhabitants are among the most highly educated in the country, with a standard of living above the average for Turkey. Transportation and communication facilities are comparatively well developed. The Porsuk River is a typical example for planning the development of beneficial uses in the Sakarya River Basin. It has a catchment area of 11 325 km 2, approximately 1.4% of Turkey's area. The river has a total length of 435.8 km, originates at the Murat Mountain, and flows in an easterly direction until its confluence with the Sakarya River. The Porsuk Reservoir is located on the river. The population in the Porsuk River basin area is approximately 600,000 and is continuously increasing with projections of a population of one million within the next 20 years (Gonenc et al. 1989, Muhammetoglu et al. 2002). The two largest cities, Kutahya and Eskisehir, are important due to their industrial activities. 4

Developing plausible water quality management strategies is important in terms of beneficial uses such as water supply, irrigation, recreation, fishing and waste transport in the Porsuk River Basin. The river is currently not used as a source of domestic water supply; other water sources such as springs and groundwater are available for this purpose. However, these latter sources are being deteriorated over time. Water is being withdrawn throughout the year in many areas of the basin by industries to meet their substantial water needs. Irrigation is considered the current most important beneficial use of the basin, and will likely be so in the future as well. The river seems unsuitable for fishing activities due to its already polluted state. It has recently started to show symptoms of hypertrophy, due to high concentrations of nitrogen and phosphorus, especially at the entrance to the Porsuk Reservoir (SWW 2001). Figure 5.7.4 presents the existing and expected status of beneficial uses in the Porsuk River Basin. Almost half of the land in the Porsuk River Basin is devoted to agricultural activities, and forests and meadows constitute the other half. Residential and industrial areas account for only about 5% of the total Basin area. The extensive and intensive agricultural activities are due to high fertility of the soil. However, irrigation is usually required in some regions to increase crop productivity (SWW 1980, SWW 2001). The majority of water resources potential of the Basin basically depends on surface water. The groundwater sources are mainly utilized by the big cities in the basin. For example, Kutahya uses 3 million m 3 year -1 and Eskisehir 18 million m 3 year -1 of groundwater for their domestic purposes, which alone accounts for 20% of the total water potential (Kefli 1994). The river is receiving water for a number of large volumes of mostly untreated industrial and domestic effluent, which have created severe water quality problems for the last two decades. Agricultural activities are the main source of nonpoint source pollution. 5.7.3 Description of Data Collected There are 11 sampling and monitoring stations along the Porsuk River. The flow rate measurements and water quality analyses are conducted by State Water Works (SWW) and by the Institute of Electrical Affairs (EIE). Over the years, the locations and the number of stations have changed; however, since 1979 the studies have been intensively conducted at the main stations on the Porsuk River as plotted on Figure 5.7.5. Some of the stations were changed in 1985. The measurements recorded over the years were evaluated within the context of this Pilot Study, and it was found that the flow-rate is subject to seasonal variations and that fluctuations even occur due to irrigation withdrawals. 5

Figure 5.7.4 Beneficial uses in the Porsuk River basin (Gonenc et al. 1989) Figure 5.7.5 Monitoring stations along the Porsuk River (Kefli 1994) 6

These 11 monitoring stations record precipitation, monitoring frequency, monitoring time and the average flow-rates during the monitoring period. According to these measurements, the average amount of water discharged to the Sakarya River from the Porsuk River tributary accounts for 16 m 3 sec -1. Additional measurements were made for almost 3 years (1983-1985) to supply data for the first modeling studies and to characterize the water quality in terms of beneficial uses. These measurements and analyses were carried-out monthly. A preliminary study was conducted to design the analysis program, the monitoring stations were selected, and sampling and analyses were simultaneously conducted on the polluting sources and at the 11 river sites during these 3 years. The measurements covered physical characteristics, general water quality variables and nutrient concentrations. These same measurements for the years 1995-2000 were made to support modeling studies by Muhammetoglu et al. (2002). The data included concentrations of inorganic nitrogen, total nitrogen, total phosphorus chlorophyll a. Table 5.7.1 shows all the variables that were measured in the river and at the industrial outfalls. A detailed survey and investigation was conducted to characterize the point and nonpoint sources of pollutants within the basin. Point sources include domestic and industrial wastewater; nonpoint sources consist of agricultural pollutants transported through surface run-off and groundwater, together with urban run-off and irrigation return flow. Although efforts were made to measure the point sources, no systematic measurements or analyses were conducted on the nonpoint sources of pollution. However, literature-based unit loads were used to estimate the nonpoint source pollutant loads (Gonenc et al. 1985). Researchers from the Pilot Study visited the major industrial plants operating in the Basin, and the production methods and wastewater quality and quantity individually investigated and quantified. Pollutant loads were calculated for each site effluent and the results checked against literature values for similar industries. All existing pollutant sources (point and nonpoint) were estimated for the year 2000. The important industries of the basin are the: Kutahya Sugar and Sugar-beet Factory, Kutahya Slaughterhouse, Kutahya Fertilizer Industry, Eskisehir Printed Cloth Textile factory, Eskisehir Engine and Railway Car Manufacturing Factory, Eskisehir Sugar and Sugar-beet Factory, Eskisehir Slaughterhouse, and Eskisehir Organized Industrial District housing a number of various installations, the majority being in the metal-finishing industry. 5.7.3.1 Water Quality and Related Regulations A comparative evaluation of the monitoring studies and water quality analyses conducted since 1979 can be made relative to the current Turkish Water Pollution Control Regulation (TWPCR 1988). This regulation groups the quality of inland surface waters into four classes based on their beneficial uses. Prior to this evaluation of prevailing water quality of the Porsuk River, information on the regulatory Water Quality Classes will be presented. Table 5.7.2 briefly summarizes the beneficial uses of each class of concern. Generally, for almost all the variables stated in the National Regulation defining the inland water classes, Class I and II water quality are preserved upstream until Kutahya city; however, the quality decreases to Class III, and even to IV, in some parts of the river between Kutahya and the Sakarya River Confluence (SWW 2001). 7

Table 5.7.1 Variables measured in the Porsuk River and in the industrial effluents (Kefli 1994) Variables Measurement at the River Measurement at the Industries Flow rate + + Temperature + + Turbidity + Suspended solids + + Settleable solids + Dissolved solids + Total solids + ph + + Conductivity + + Salinity + Dissolved oxygen + BOD 5 (unfiltered) + + COD + + NH + 4 - N + + NO - 2 -N + + NO - 3 -N + + Chloride + Alkalinity + + Total Hardness + + Phosphate + Iron + Cyanide + Heavy metals + + Table 5.7.2 Definition of Beneficial Uses of Each Class of Inland Surface Waters (TWPCR 1988) CLASS I High Quality Water Drinking water supply- after disinfection Protection & enhancement of aquatic life including trout breeding Animal breeding, farm supply Swimming and recreation Irrigation Others CLASS III Polluted Water Industrial water supply- after appropriate treatment (except for food and textile industry) CLASS II Sparingly Polluted Water Drinking water supply-after conventional treatment Protection & enhancement of aquatic life excluding trout breeding Animal breeding-after disinfection or plain settling Swimming and recreation Irrigation Industrial water supply CLASS IV Highly Polluted Water Surface waters with lower quality than that indicated for Classes I, II, and III. Transportation /Navigation Waste transport 8

5.7.4 Brief Description of the Models Used The river models used can be divided into two categories: simulation models and optimization models. Selection of the appropriate model depends on the utilization purpose, and is considered the most critical part of river quality management studies. This is because the model is expected to yield the necessary directions for an implementation program, as is the case in this study. It was initially decided that a one-dimensional model fit well to the river's characteristics since measurements and analyses indicated that almost no variations occurred as a function of the cross-sectional depth (Gonenc et al. 1985). A steady state model was also assumed to suit the situation; that is, for the purpose of long-term water quality planning (Loucks 1981). The selected model would also have to be capable of consecutive simulations in order to characterize the seasonal flow fluctuations due to precipitation and those due to reservoir operations and irrigation withdrawals. Based on preliminary evaluations, the MODQUAL Model, which is a modified version of QUALII, was initially selected as the most appropriate model to satisfy all the modeling objectives set for the Porsuk River. A detailed description of the MODQUAL model is given in the literature (Roesner et al. 1977, Van Pagee 1984, Menet 1985). Another important fact that supported the use of this model was that MODQUAL had been successfully applied to the River Rhine where many characteristics resembled those of the Porsuk River. MODQUAL basically divides the river system into reaches, each composed of a number of computational elements, where allowance can be made for waste load inputs, inflows, and withdrawals. Within a reach, the geometry, hydraulic parameters, process variables, and other constraints are assumed to remain constant. For selected modeled constituents, the differential equations are solved numerically by a finite difference method. A one dimensional mass transfer equation is used, based on the assumption that there exists homogenous mixing across the river's cross-section. The model simultaneously simulates the variations in time and space of the variables listed below: Dissolved oxygen, Biochemical oxygen demand, Chemical oxygen demand, Algae (chlorophyll a), Ammonia, nitrite, nitrate and organic nitrogen, Ortho-phosphate, and organic and particulate phosphorus, Detritus, Temperature, Additional three conservative variables, Additional three non-conservative variables. The model needs the following input data: The selection of output and the water quality variables that will be involved in the simulation, The division of the river into reaches and computational elements, The specification of the coefficients characterizing kinetic mechanisms, 9

The specification of geometric and hydraulic parameters for calculating flow-rate, depth, volume and cross-sectional area, The specification of initial conditions; i.e., the temperatures, flow-rates, and pollutant concentrations at boundaries and at polluting sources. The main output of the program is the simulated values of the specified water quality variables at all the computational elements along the river. The model was applied to the Porsuk River from Station 1 (Agackoy) to the Sakarya River confluence for its calibration. In a previous study (Kefli 1994) an uncertainty analysis for the Porsuk River was conducted by using the first order error analysis option of the QUAL2E-UNCAS program in conjunction with the calibrated Porsuk River Model on the variables BOD and DO. The objective of applying uncertainty analysis to the Porsuk River was to provide some of the tools needed to incorporate uncertainty analysis as an integral part of the water quality modeling process. QUAL2E-UNCAS was shown to provide a useful framework for performing uncertainty analysis in steady-state water quality modeling. The impetus for this concern was provided by public awareness of the potential health risks arising from improper disposal of wastes. One of the first steps in the chain of risk assessment was the quantification of the error in predicting water quality. Uncertainty analysis has been the subject of many debates in the ecosystem modeling community (O'Neill and Gardner 1979, Rose and Swartzman 1981, Malone et al. 1983). A recent modeling study on the Porsuk River-Porsuk Dam Reservoir (PDR) system was conducted to estimate its response under various management scenario options since the existing water quality shows a hypertrophic state prevailing in the reservoir (Muhammetoglu et al. 2002). Changes within the Porsuk River system and quantification of pollution loads to the PDR under different scenarios were studied using QUAL2E. The responses of the PDR under these scenarios were examined using the software BATHTUB (Walker 1999). The river water quality was modeled for three distinct seasons, namely: winter, summer and the dry period. The simulated length of the river was 160 km. This length was divided into 11 reaches based on the hydraulic characteristics and river morphology. The length of the computational elements was chosen as 1 km. The simulated variables were temperature, nitrogen and phosphorus compounds, dissolved oxygen, biochemical oxygen demand, and chlorophyll a. 5.7.5 Calibration of Models The MODQUAL model was calibrated using a yearly average simulation for 1983; various simulations using both yearly and monthly averaged periods from 1979 to 1986, were used for verification (Menet 1985, Durdu 1986). Although the general agreement between calculated and observed values was satisfactory enough, the rapid changes in the river flow regime caused by precipitation, by irregular discharges from the reservoirs, and by the seasonal changes in the industrial loads caused by the production schedule of the industries (mainly sugar-beet factories), produced extreme variations that affected the reliability of the yearly average data (Project Report 1989). Figure 5.7.6 shows the results comparing model outputs with experimental field data for selected state variables at Station 2. 10

Comparison of field data with model results, even for monthly average values, reveals that the model is quite a satisfactory approximation to assess the dissolved oxygen, BOD, nitrogen and phosphorus profiles in the river, in spite of the rather rough estimates of the pollution loads. The idea in water quality modeling is to appropriately describe the interactions between existing and future desired water quality of a river basin and the various polluting sources. The model becomes a useful tool to provide necessary information to water resources management. A comparative evaluation of simulated water quality parameters in the river versus those values desired indicated that the polluting sources required corrective measures. This modeling approach has converted the evaluation into a waste load allocation exercise, whose results for the Porsuk River Basin will be discussed in the following section. Figure 5.7.6 Monthly average simulations for selected state variables at monitoring station 2 (Calca) between March 1984- February 1985 (Gonenc et al. 1989) First order uncertainty analysis had been applied to the Porsuk River by Kefli (1994) as mentioned previously. The simulations were only done for BOD and DO. The BOD uncertainty was primarily the result of parameter uncertainty associated with the point sources of pollutants. However, uncertainty related to nonpoint sources produced BOD standard deviations as low as 0.183 mg L -1, which is basically due to wrong assumptions and to insufficient data for nonpoint source pollutants. The BOD simulation results indicated that the total difference between calibration data and simulation results vary from 0.156 mg L -1 to 0.912 mg L -1. The total deviation in the dissolved oxygen (DO) results (calibration data versus simulated values) along 11

the river did not exceed 5% of the DO concentration. The results obtained from BOD and DO simulations after performing first order analysis to Porsuk River is shown in Table 5.7.3. Table 5.7.3 BOD and DO Standard Deviations derived for Porsuk River (Kefli 1994) Total Std. Dev. for BOD (mg l -1 ) 0.156 0.912 0.765 0.615 0.696 Total Std. Dev. for DO (mg l -1 ) 0.348 0.290 0.188 0.237 0.231 A more precise evaluation of the variables contributions to the level of simulated uncertainty depends on obtaining more accurate data. The recent application of QUAL2E by Muhammetoglu et al. (2002) was calibrated using data collected during the winter season of 2000, and then verified with other data sets from the summer season of the same year. All the calibrated coefficients were within the value ranges reported in the literature. Satisfactory agreement was achieved between the model predictions and the field measurements. Figure 5.7.7 shows the model predictions and field measurements for inorganic nitrogen and BOD for the calibration and verification periods, as an example. Figure 5.7.7 (a) Calibration inorganic nitrogen concentrations in the winter season of 2000, (b) verification inorganic nitrogen concentrations in the summer of 2000, and (c) calibration BOD concentrations in the winter of 2000 (Muhammetoglu et al. 2002) 12

5.7.6 Discussion of Modeling Results The first model runs attempted in this Pilot Study focused on a selected set of water quality parameters to show the actual polluting impact of discharges and to obtain information regarding the benefit of possible treatment alternatives that might be imposed on different sources of the pollution. For the Porsuk River, pollution loads have resulted in a gradual deterioration of the river s water quality. Figure 5.7.8 presents the simulation outputs of the verified model in terms of the water quality classification system adopted for Turkey, and clearly shows that the water quality in the Porsuk River is currently unfit for any possible beneficial use for almost its entire stretch, based upon the majority of the water quality parameters considered. The second simulation runs evaluated the water quality benefits of imposing wastewater treatment on the polluters in such a way that they all comply with the general technology-based discharge quality regulations. An appropriate treatment technology was defined for each polluter, for the purpose of lowering the relevant water quality parameters to levels specified in the national standards; i.e., BOD 5, COD and TSS for the sugar industry, and nitrogen, COD and TSS for the fertilizer industry. For variables for which no limits have been set, the minor removals provided by the conceptual treatment system were also accounted for in the simulation. Although producing significant amelioration in terms of river water quality variables like dissolved oxygen, BOD 5, and COD, the results shown in Figure 5.7.9, clearly indicate that no significant improvement would be achieved using that strategy as far as nutrients are concerned. This result is an important concern for the basin, since eutrophication is considered to be the most serious threat to the Porsuk Dam Reservoir, which is being considered as a potential future source of water supply. A subsequent more careful analysis identified domestic discharges, the fertilizer plant, and the industrial organized district as the major sources of nutrient pollution. Implementing Best Achievable Technologies, defined for each individual source, would provide additional removal efficiencies of up to 80-90% for nutrients. Implementing BAT pollution controls in the model produced a noticeable improvement in all the water quality parameters, including nutrients, as presented in Figure 5.7.10. These results suggest that bringing the whole Porsuk River to at least a Class II status can be achieved. 13

Station 1 Station 2 Station 3 Station 4 Station 5 Station 6 Station 7 Station 8 Station 9 Station 10 Station 11 Sakarya River DO BOD 5 COD TKN NH 3 -N NO - 2 -N Total P Figure 5.7.8. Model simulations for current discharges (Gonenc et al. 1989) Class 1 Class 2 Class 3 Class 4 Station 1 Station 2 Station 3 Station 4 Station 5 Station 6 Station 7 Station 8 Station 9 Station 10 Station 11 Sakarya River DO BOD 5 COD TKN NH 3 -N NO - 2 -N Total P Class 1 Class 2 Class 3 Class 4 Figure 5.7.9 Model simulations reflecting the effect of implementing industry-specific, technology-based treatment technologies on all pollution sources (Gonenc et al. 1989) 14

Station 1 Station 2 Station 3 Station 4 Station 5 Station 6 Station 7 Station 8 Station 9 Station 10 Station 11 Sakarya River DO BOD 5 COD TKN NH 3 -N NO - 2 -N Total P Class 1 Class 2 Class 3 Class 4 Figure 5.7.10 Model simulations reflecting the impact of implementating advanced (BAT) treatment technology on all pollution sources (Gonenc et al. 1989) Our modeling evaluations point out that reaching a Class II quality status is technically possible, but will require additional and costly measures to remove nutrients. This observation suggests that a locational, beneficial use-related water quality management approach will likely be a much more cost effective pollution control strategy. As reflected in Figure 5.7.11, using the model to specify a most appropriate treatment technology for each pollution source (based on impact and cost) can produce a spectrum of beneficial uses, without BAT treatment at many reaches of the river. The water quality in all reaches is expected to support the projected desired beneficial uses in the basin (Gonenc et. al. 1989). 15

Station 1 Station 2 Station 3 Station 4 Station 5 Station 6 Station 7 Station 8 Station 9 Station 10 Station 11 Sakarya River AGRICULTURAL WATER SUPPLY INDUSTRIAL WATER SUPPLY DRINKING WATER SUPPLY AFTER SIMPLE TREATMENT DRINKING WATER SUPPLY AFTER CLASSICAL Figure 5.7.11 Beneficial uses secured by the model-designed most appropriate treatment technology (Gonenc et al. 1989) The most important outcome of this study was to identify the desired major beneficial uses and to define them in terms of the technical water quality parameters incorporated in the mathematical model. The study enabled us to propose a sound waste load allocation approach to the implementing authority for effective control of the polluting sources. However, since 1989 no significant reduction in pollution loads has been realized causing even further deterioration of the Porsuk River Basin water quality. This statement is clearly supported by the recent application of QUAL2E using year 2000 values. It is seen that only limited improvements in water quality can be achieved by conventional treatment of domestic wastewater discharges and complying with the TWPCR criteria for industries because of the low nutrient removal efficiency achieved. Tertiary treatment of all industrial discharges using Best Available Treatment plus 50% reduction of N and P in drainage water will improve the water quality of the Porsuk River and Porsuk Dam Reservoir. Thus, the trophic state of the Porsuk Dam Reservoir might be shifted from its highly hypertrophic state according to OECD criteria (OECD 1982) to a eutrophicmesotrophic state (Muhammetoglu et al. 2002). 5.7.7 Conclusions and Recommendations Water quality models can be used as predictive management tools. Within the context of this case study, one of the important rivers of Turkey is taken as an example where modeling studies were carried-out over the last two decades. QUAL2E modeling was conducted in an integrated manner to predict the response of the river basin to various pollution control scenarios. Beyond such modeling efforts, usually conducted by scientists of state organizations like universities and research institutes, local, regional and central government authorities must evaluate the model outputs and try to integrate and incorporate the findings into the technical and socio-economic development policies of the country. To develop such an integrated strategy, the decision-makers must cooperate with the different levels of administration and the public. A 16

balanced and sustainable development policy relative to the equitable distribution and utilization of highly polluted water resources must be developed through preparation and implementation of technically and socio-economically feasible plans, based on the modeling outputs. 17

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SWW. 1980. Protection of Inland Water Quality - Porsuk River Pilot Project, TUR//777019 Final Report, State Water Works, Ankara. SWW. 2001. Management Plan for Porsuk Watershed, Final Report, State Water Works, Ankara. TWPCR. 1988. Turkish Water Pollution Control Regulation, Official Newspaper, September 4, 1988, Ref no: 19919. Van Pagee, J. A. 1984. Water Quality Modeling of the Rhine River and its Tributaries in Relation to Sanitation Strategies. Water Science and Technology. 16(5-7):393-406. Walker, W. W. 1999. Simplified Procedures for Eutrophication: User Manual. US Army Corps of Engineers, Waterways Experiment Station, Vicksburg, MS. 19