Tool closes the gap between fresh water supply and demand

Changes in climate, land use, and population can increase annual and interannual variability of socioeconomic droughts in water-scarce regions. This study develops a probabilistic approach to improve characterization of sub-annual socioeconomic drought intensity-duration-frequency (IDF) relationships under shifts in water supply and demand conditions. A mixture Gamma-Generalized Pareto (Gamma-GPD) model is proposed to enhance characterization of both the non-extreme and extreme socioeconomic droughts. Subsequently, the mixture model is used to determine sub-annual socioeconomic drought intensity-duration-frequency (IDF) relationships, return period, amplification factor, and drought risk. The application of the framework is demonstrated for the City of Fort Collins (Colorado, USA) water supply system. The water demand and supply time series for the 1985–2065 are estimated using the Integrated Urban water Model (IUWM) and the Soil and Water Assessment Tool (SWAT), respectively, with climate forcing from statistically downscaled CMIP5 projections. The results from the case study indicate that the mixture model leads to enhanced estimation of sub-annual socioeconomic drought frequencies, particularly for extreme events. The probabilistic approach presented in this study provides a procedure to update sub-annual socioeconomic drought IDF curves while taking into account changes in water supply and demand conditions.

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Water-Stressed Pakistan

Asian Survey ◽

10.1525/as.2019.59.6.1116 ◽

2019 ◽

Vol 59 (6) ◽

pp. 1116-1136

Author(s):

Amit Ranjan

Keyword(s):

Water Supply ◽

Supply And Demand ◽

Agriculture Sector ◽

Available Water ◽

Water Supply And Demand

The widening gap between water supply and demand is the biggest threat and challenge before Pakistan. Of the available water, much is polluted. Both scarcity and pollution threaten the agriculture sector, on which the country’s economy depends.

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Thermoeconomic Analysis of a Solar MVC Desalination System

Volume 6B: Energy ◽

10.1115/imece2018-86212 ◽

2018 ◽

Author(s):

Lei Gao ◽

Yunho Hwang ◽

Gyeong Sung Kim

Keyword(s):

Water Supply ◽

Fresh Water ◽

Great Influence ◽

Operating Conditions ◽

Specific Power ◽

World Population ◽

Vapor Compression ◽

Solar Pv ◽

Pump System ◽

Fresh Water Supply

Globally, about 10% of the world population does not have access to enough fresh water. In many hot-and-dry coastal regions and islands, the desalination of seawater might be the only practical option to have a fresh water supply. Therefore, low-cost desalination system is critical for freshwater demands. To address this issue, a desalination system consisting of solar photovoltaic (PV) and mechanical vapor compression subsystem is proposed in this study. The entire desalination system was modeled and designed to produce 10,000 m3 of fresh water per day at the coast of San Francisco, California. Key components such as water vapor compressor, solar PV panel, and three-stream heat recovery unit were designed, and their performances were analyzed. The effects of design variables and operating conditions on the system performance were investigated through a parametric study. Finally, an economic analysis was conducted and compared with current desalination technologies. The analysis results show that the specific power consumption of desalination system can reach 14.4 kWh/m3 when the evaporation temperature is 70°C. It is found that the evaporating temperature has a great influence on the heat pump system efficiency and evaporator design. The levelized cost of the proposed system is $0.76 per m3 of fresh water which is lower than current grid-powered vapor compression desalination system and other thermal desalination systems. The proposed solar PV driven desalination improves thermoeconomics of desalination system by applying low-lift operating condition to the vapor compression cycle so that it can contribute to solving the fresh water supply challenges.

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