Evaluation of water shortage problems in the Han River basin, Korea and desalination as a countermeasure

This study evaluates the role of additional constant water resources to the variable water resources. The variable water resources indicate dam reservoirs, whereas the constant water resources indicate desalination. This study focuses on the water supply system in the Han River basin, Korea, particularly on the increasing failure frequency of water supply. As a first step, this study evaluates the changing trends in water supply failures over the last 50 years. Frequency analysis of both shortage frequency and shortage volume is conducted. Also, the same analysis is repeated while considering the addition of constant water resources. The difference between the two is then quantified as the effect of additional constant water resources. The results are summarized as follows. Frequency analyses result show that the water shortage problem has significantly worsened recently. For example, the occurrence probability of 20 or more water shortages over the 30-year period was almost zero in the 1980s; however, it has now approached one. Similarly, the return period for the shortage ratio of 0.2 was more than 400 years in the 1980s; but has now decreased to less than 30 years. The effect of additional constant water resources is found to be significant. With an additional constant water resources of 1.0 × 10⁶ m³/day, the occurrence probability of 20 or more water shortages decreases from nearly 1.0 to around 0.6, which can also increase the return period for the shortage ratio of 0.1 from 10 years to about 20 years.