FORMULATION, CALIBRATION AND VERIFICATION OF A MATHEMATICAL MODEL FOR PINIOS RIVER, GREECE

摘要

In the present work a relatively simple 1-D mathematical model is developed, calibrated and verified for the modeling of water quality of Pinios River, Greece. This work is the first step towards the formulation of a more complicated model, which together with other models, such as MIKE-SHE, will constitute a useful tool for the management of the waters of Pinios River within the framework of the EU Waterframe Directive. For the construction of the model the code RISQ-1D (River and Stream water Quality in 1 Dimension) is used, which has been developed in the Laboratory of Applied Hydraulics of the National Technical University of Athens. The mathematical model is based on mass balance equations for the BOD_5and the DO, derived by applying the mass conservation principle to an elementary, finite, control volume within the flow. Regarding the study area, the main pollution sources are the point sources of (i) effluent discharges originating from domestic Wastewater Treatment Plants (WWTP), (ii) industries having or not a WWTP with partial treatment and (iii) tributaries of the Pinios River. There was no information on the diffuse sources of pollution originating from agricultural activities, these were assumed to be included in the point loads. The calibration and verification of the model are performed with (a) very limited data and field measurements of the year 1998 and (b) hydraulic characteristics, which were determined from the application of the model MIKE-SHE in the greater Catchment area of Pinios River. An indicative part of the process of model calibration for July is shown in Figure 2. Taking into account (a) the significant level of uncertainty and scarcity of the available field measurements and (b) the uncertainty of the estimations of pollution loads, the agreement between model predictions and field measurements can be characterized as satisfactory. Moreover, a discrepancy is observed in the period August-December during which the model calculations of DO concentrations do not verify the fact that the water quality is not satisfactory in this period. Therefore, the model can be used in its present formulation only as an approximate tool for the water management of Pinios River.