ADAPTATION STRATEGIES TO IMPACTS OF CLIMATE CHANGE AND VARIABILITY ON TEHRAN WATER SUPPLY IN 2021 : AN APPLICATION OF A DECISION SUPPORT SYSTEM (DSS) TO COMPARE ADAPTATION STRATEGIES

Sammanfattning: In this thesis, the decision analysis process of investigating the best optimal strategy for Tehran water management in 2021 is described. Such process is normally divided into four steps including: structuring the problem; identifying feasible strategies, their impact and uncertainty; quantifying preferences; and evaluation of countermeasures and sensitivity analysis. Here, in order to structure the problem, the characteristics of Tehran with respect to water issues and its history of water management are reviewed. The state of surface waters and ground waters and a description of Tehran plan for waste water treatment are given, the most significant constraints of Tehran water sector are classified and the challenges of climate change and variability are explained. The feasible adaptation strategies are designed subsequently based on that classification, data extracted from a survey and a number of interviews with water officials and managers and ordinary citizens in Tehran. Each strategy contains a series of separate measures with different weights. The phase of quantifying preferences and elucidating utility functions is conducted based on the data available from previous studies and also the current survey. The measures include: installing water saving devices, awareness raising to change citizens’ water consumption pattern, adding new sources of surface water, investing on waste water utilization, migration control and repairing water distribution network.Different combinations of these measures provide different possibilities for formulating adaptation strategies. We compare two more discussed adaptation strategies of the spectrum of strategies; one is inclined toward exploiting more water resources while the other one is more focused on demand management. The former is mainly supported by water officials and the latter advocated by water experts we interviewed. The criteria of comparison are social acceptability, economic feasibility, time-efficiency and environmental tenability. By considering the uncertainty attributed to the criteria weights, the WEB-HIPRE DSS analysis shows that the demand-oriented strategy is the optimal one in most cases, however, if time-efficiency and/or economic feasibility gain very high significance, the strategy of water officials wins over that of experts.