The Yamada Weir has a long and interesting history dating back to 1663. It was first built during the Edo period on the right side of the Chikugo river to save the farmlands from drought. Construction of the Yamada Weir was completed in 1790 and in spite of numerous floods, has maintained its original form.
The Yamada Weir pulls water from the Chikugo River to the surrounding rice fields, totalling 652 hectares. The sophisticated design of the Yamada zeki, inclined at a 20 degree angle to the current, alleviates the Chikugo River’s high water pressure and works to control flooding. The Chikugo kawa is one of three rivers in Japan most likely to flood and is the longest river in Kyushu.
During Japan’s Edo period many other dams like the Yamada Weir were built to assist the cultivation of farmlands often affected by flooding. Asakura’s Yamada Weir is the only one that remains in its original form and is still in use today. In 2014, the dam was recognised as a “World Heritage Irrigation Structure (WHIS) by the International Irrigation Drainage Committee (ICID).
Dr. Testu Nakamura (1946-2019), born in Fukuoka city, was particularly fond of the Yamada Weir. In the later years of his life, Nakamura worked tirelessly to relieve the drought-stricken region of eastern Afghanistan by building an irrigation channel, based on the Yamada Weir. Famously, Dr Nakamura is often quoted as saying, “One irrigation canal will do more good than 100 doctors.”
19 years after the onset of drought in 2000, Dr. Nakamura successfully brought the Yamada Weir model of irrigation to Eastern Afghanistan. He helped transform the Gamberi desert into productive wheat farmlands and in doing so revitalised the desert stricken land and gave new life to the impacted communities. Following the success of the Kama Weir, the Government of Afghanistan declared the design and construction of the irrigation system as their own national standard.
