Land and Resources, Rivers and Lakes
Lake Kussharo, Kurobe Dam, Tone River, Toyama Prefecture, Biwa
Most of Japanís rivers are relatively short and swift flowing. Only a few are navigable beyond their lower courses. Japanís longest river, the Shinano, arises in the mountains of central Honshu and flows for 367 km (228 mi) to empty into the Sea of Japan. Other major rivers are the Tone River in the northern Kanto Plain and the Ishikari River in Hokkaido.
Rivers in Japan often have low water levels during dry seasons but may flood during rainy periods and after winter snows melt. Except in the highest mountains, the courses of almost all rivers have been altered by flood control measures such as artificial channels and levees. In addition, many rivers have multiple dams and chains of reservoirs to regulate water flow and to supply cities and farms downriver with water for industry, irrigation, and domestic use. The dams also generate electric power. Japanís largest dam is the Kurobe Dam, standing 186 m (610 ft) high, on the Kurobe River in Toyama Prefecture.
Japanís largest lake, Biwa, lies in central Honshuís Shiga Prefecture. It measures 670 sq km (260 sq mi) and is 104 m (341 ft) deep at its deepest point. Biwa is a popular scenic attraction, an important source of freshwater fish, and a local transportation artery. Japanís second-largest lake is Kasumiga-ura, located in the central Honshu prefecture of Ibaraki. It measures 168 sq km (65 sq mi) and is an important source of eel, carp, and other freshwater species. Lake Kussharo in Hokkaido is an example of a caldera lake. It measures 80 sq km (31 sq mi) and has an island in its center formed by a volcano. The waters of this lake are acidic and barren of fish.
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