Gakunan

...There are many rapid rivers with abundant water volume in the western half, such as the Tenryu River, the Oi River, and the Abe River, which flow south in vertical valleys and develop alluvial fan plains made of thick gravel layers along the coast, such as the Enshu Plain, the Oigawa Plain, and the Shizuoka Plain. The Fuji River is large in the eastern half, but its flow length within the prefecture is only 18 km, and the downstream Gakunan Plain and the Kitaizu Plain in the lower Kano River basin are also smaller in scale than the plains in the western half. The western half is also characterized by the large number of alluvial plateaus, such as the Mikatahara, Iwatahara, and Makinohara, adjacent to the plains.

*Some of the terminology that mentions "Gakunan" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…河川は天竜川，大井川，安倍川など西半部に豊かな水量をもつ急流が多く，縦谷をなして南流し，海岸沿いに遠州平野，大井川平野，静岡平野など厚い砂礫（されき）層からなる扇状地性の平野を発達させる。東半部では富士川が大きいが，県内での流長は18kmにすぎず，下流の岳南平野，狩野川下流域の北伊豆平野も西半部の平野に比べると規模が小さい。西半部には平野に隣接して三方原，磐田原，牧ノ原などの洪積台地が多いのも特徴的である。…

※「岳南」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報