چكيده به لاتين
This paper deals with optimal structure design of increasing block tariff (IBT) with respect to as many as possible rate setting objectives which include revenue sufficiency, economic efficiency, social equity and water conservation which are defined based on water demand and cost functions. Accordingly, many-objective particle swarm optimization (MaPSO) is employed to solve the problem where it is applied to drinking water tariff setting of Tehran Metropolis, capital of Iran. The new metholdogy is also compared with the well-known Ramsey pricing. Tehran’s domestic water users are categorized into 10 blocks. Thus, at first, we propose block-specific water demand functions based on nonlinear regression where we account for independent variables like temperature, number of households, water price and household income. Moreover, we estimate annual water cost function as a trans-log function of annual water consumption and other inputs, i.e. labor price, capital price, other services price, raw materials price and water production volume. Results indicate that the many-objective based optimal compromised water tariff respectively equals 3612 and 34464 IRR.m-3 for the first and tenth classes, i.e. first class used 0 until 5 m3. and tenth class used upper than 50 m3. Furthermore, we demonstrate that the optimal prices in all classes are higher than the current prices; hence, we recommend increase in Tehran’s domestic water tariff . Finally, to ensure the accuracy of the results, we compare them with the results of the Ramsey model.
