Introduction
"There are hardly any other rivers like this!"
"Only a little rain is enough to cause stones to flow down, loudly crashing into each other and sending up a shower of sparks!" This is how Joganji River is commonly described.
Described as not so much a river but as a waterfall, this is Japan's swiftest flowing river which has frequently caused flooding with debris flow due to the climate characterized by high rainfall and snow, the extensive area of collapsing land and a huge volume of unstable sediment in the catchment area.
It is naturally the belief of the people living in Toyama Prefecture that a levee breakage of Joganji River would turn Toyama into a sea of mud, underlining their natural fear of the devastating implications of the flooding of Joganji River.
The history of Toyama Prefecture has been a history of river improvement since the Meiji Era. In their strenuous efforts to control Joganji River, the people of Toyama have brought good out of bad, initiated hydropower generation to promote local industries and fostered a prosperous, high quality local culture.
We will be extremely honored if this booklet reviewing the past and present of Joganji River facilitates understanding of the objectives of sabo (sediment control) works.
Table of Contents
Tateyama Mountain Area Sabo Office
The Tateyama Mountain Area Sabo Office is responsible for erosion and sediment control in the upper reaches of Joganji River, i.e. the catchment basin upstream of Kamitaki which includes the sub-basins of such tributaries as Makawa River, Yukawa River and Shomyo River. The Tateyama Mountain Area Sabo Office has implemented a series of sabo works to protect the Toyama Plain from sediment disasters. The sabo facilities have been systematically constructed, including a number of consolidation works, hillside works and revetment works in addition to more than 100 sabo dams.