Waju

A wajū (輪中; lit. 'inside the circle') Japanese pronunciation: [wa(d)ʑɯː] is a hydraulic engineering and flood control structure unique to the alluvial floodplain of the Kiso Three Rivers in central Japan. It is comparable to the European polder, although a wajū is usually not reclaimed. The hardships endured for centuries by farmers whose lives revolved around the wajū has given rise to the term "wajū spirit" (輪中根性, wajū konjō).