A Holistic Approach to Historical Living Spaces: Ponds and Reservoirs in Sanuki, a Region with Low Annual Rainfall in the Seto Inland Sea, Japan

This article focuses on ponds and reservoirs (PRs) in Sanuki, Kagawa Prefecture, Japan. Sanuki is a region in the Seto Inland Sea with low annual rainfall. In 1999, there were 14,619 PRs in the 1,877-square-kilometer area. Mannō-ike, the largest PR, is said to have been constructed at the beginning of the ninth century by Kūkai, one of Japan's most prominent Buddhist monks. Such huge man-made structures could have been achieved only through collective human labor. The motivation to build large PRs was driven by the risk of drought. However, it is important to note that there were many more small PRs managed by individuals or families than one might imagine. PRs can range in size from huge to small and in location from mountainous areas to mountain foothills and plains. Rather than hard clustering, which classifies PRs according to a single logic, this article takes a new, historically holistic approach by using soft clustering to analyze the classification mechanism by considering the "Living Spaces," the world of all living organisms, including humans, and quantifying its complex logic.