Goal programming model for optimal water allocation of limited resources under increasing demands

A multi-objective model has been applied for optimal allocation of water from limited resources to meet increasing demands in multiple sectors. The study region is Saudi Arabia, while the time span is from 2020 to 2050 with interval of 10 years. The available water resources in Saudi Arabia are groundwater (GW), surface water (SW), desalinated water (DW) and treated wastewater (TWW), whereas the users are domestic, agricultural and industrial sectors. The goal programming technique has been used to formulate the model with multiple objectives. These objectives are (1) water demands satisfaction; (2) water quality control; (3) maximizing allocation of SW and TWW; and (4) minimizing extraction of GW, overproduction of DW and overall cost of water use. Allocations of GW, SW and DW in domestic sector are 508.4, 225.7 and 2174.2 MCM, respectively, in 2020, which are projected to be 585.3, 349.1 and 4494.8 MCM, respectively, in 2050. From 2020 to 2050, contribution of GW and SW in agricultural sector may reduce from 10,283.5 and 218.7 MCM to 8753 and 95.2 MCM, respectively, while this reduction is recovered by increasing contribution of TWW from 2291.9 in 2020 to 3945.8 MCM in 2050. During this period, contribution of GW in industrial sector shows increasing rate of approximately 171 MCM per year. Water quality is controlled through controlling the level of total dissolved solids to the standards. Production of DW and TWW has to be increased in order to meet the future needs. The total cost of using water is estimated as 13 billion US$ in 2020, which is predicted to be 22 billion US$ in 2050. This study attempted to suggest the possible scenarios to satisfy increasing water demands from limited resources in different regions of Saudi Arabia. Such scenarios can contribute in developing sustainable strategies for water resources management in water deficit regions.