Sustainability Assessment of the Water Management System for the Boukan Dam, Iran, Using CORDEX- South Asia Climate Projections

Farzad Emami,Manfred Koch

doi:10.3390/w10121723

Abstract

The present study aimed to quantify the future sustainability of a water supply system using dynamically-downscaled regional climate models (RCMs), produced in the South Asia Coordinated Regional Downscaling Experiment (CORDEX) framework. The case study is the Boukan dam, located on the Zarrine River (ZR) of Urmia’s drying lake basin, Iran. Different CORDEX- models were evaluated for model performance in predicting the temperatures and precipitation in the ZR basin (ZRB). The climate output of the most suitable climate model under the RCP45 and RCP85 scenarios was then bias-corrected for three 19-year-long future periods (2030, 2050, and 2080), and employed as input to the Soil and Water Assessment Tool (SWAT) river basin hydrologic model to simulate future Boukan reservoir inflows. Subsequently, the reservoir operation/water demands in the ZRB were modeled using the MODSIM water management tool for two water demand scenarios, i.e., WDcurrent and WDrecom, which represent the current and the more sustainable water demand scenarios, respectively. The reliability of the dam’s water supply for different water uses in the study area was then investigated by computing the supply/demand ratio (SDR). The results showed that, although the SDRs for the WDrecom were generally higher than that of the WDcurrent, the SDRs were all <1, i.e., future water deficits still prevailed. Finally, the performance of the water supply system was evaluated by means of risk, reliability, resiliency, vulnerability, and maximum deficit indices, and the combination of the indices to estimate the Sustainability Group Index (SGI). The findings indicated that, compared to the historical period for both the water demand scenarios, WDcurrent and WDrecom, the average SGI of each RCP would be decreased significantly, particularly, for the more extreme RCP85 scenario. However, as expected, the SGI decrease for the WDrecom was less than that of the WDcurrent, indicating the advantage of implementing this more sustainable water demand scenario.

Highlights

The growing population rate and the limitations of available water resources as a vital factor for human survival will increase the likelihood of water scarcity in future years
For allWater the RCP/period combinations, the sustainability group index (SGI) are systematically higher for WDrecom than for WDcurrent, and
A combination of the Soil and Water Assessment Tool (SWAT) with the MODSIM model was applied to evaluate the possible impacts of climate change on the water supply system performance in terms of sustainability for WDcurrent, and unless some adaptation strategies and policy changes to a lower emission scenario are implemented, the water sustainability in the ZR basin (ZRB) will deteriorate tremendously in the future

Summary

Introduction

The growing population rate and the limitations of available water resources as a vital factor for human survival will increase the likelihood of water scarcity in future years. This holds in particular, for countries located in areas with arid and semi-arid climates, such as Iran in southwest Asia. Based on evidence from the GRACE (Gravity Recovery and Climate Experiment) satellite data [2], NASA has found that large parts of the arid Middle East region and western Iran have lost freshwater reserves rapidly over the past decade This situation is exacerbated by the rising trends in climate variability due to global climate change, with the effect. The first inevitable task to prepare the potentially affected regions for these adverse events is to identify recent, as well as future, climate variations and to assess the water scarcity risk, followed by a prediction of the effects of the events on future hydrology to allow the definition of adaptation plans to mitigate the aforementioned negative impacts on the water supply systems

Methods

Results

Conclusion