A Study of Purification in Pine Forest Soils after Salt Damage from the Tsunami in Enjugahama Beach, Wakayama Prefecture

Abstract

The purpose of this study was to examine the feasibility of using a river as a water source for purification of soil damaged by the tsunami in a pine forest in Enjugahama, Mihama town, Wakayama prefecture, and to create a “purification map” visualizing the amount of purification water. Soil from the pine forest was placed in a plastic container and seawater was poured into it, followed by river water. The amount of water required for soil purification was determined by measuring the EC at this time. It was confirmed that 333,364 m3 of water would be required to purify the entire pine forest, which is approximately 1 km2. The time required to collect this volume of water from the West River would be 265 h (about 2 weeks) for an average flow rate. These results were aggregated to create the purification map. Using this map, it is possible to estimate the amount of water needed for purification at any given point and to make decisions, such as prioritizing areas that are easier to purify, thereby contributing to the purification of pine forests after tsunamis. However, it could be said that purification would be difficult in cases where seabed sediments have been deposited on the soil.