Raindrop erosion

Japanese: 雨滴浸食 - うてきしんしょく

…Rain wash is the process by which rainwater directly erodes the land. Rain erosion includes splash erosion, in which rainwater collides with the soil and moves it; rill erosion, in which rainwater flows over the ground and turns into rills, which move the soil particles and create shallow depressions in the ground; sheet erosion, in which numerous rills cover the ground and spread out, resulting in shallow erosion of the land as a whole; and gully erosion, in which rills gather and carve gullies. Rain erosion is most noticeable on gentle slopes such as the foothills of volcanoes, flat surfaces such as continental plateaus, and terraced surfaces, and occurs in places relatively higher than the head of a river valley. …

From [Soil Erosion]

…The impact of raindrops on the land causes soil particles to disperse and become muddy, forming a dense, poorly permeable layer on the soil surface. As a result, the rainwater is unable to infiltrate into the ground and suspends the soil, running off down the slope (raindrop erosion). When rainwater, melting snow, or melting ice runs off over a wide area, the soil surface first runs off in a thin layer (this is called planar erosion, surface erosion, layer erosion, etc.). …

*Some of the terminology explanations that refer to "raindrop erosion" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…雨食rain washは雨水が直接に土地を削り取る作用で雨洗ともいう。雨食には降雨が衝突して土を動かす雨滴浸食splash erosion，雨水が地表を流れて細流(リルrill)となり，土粒が動かされて地面に浅いくぼみがつく細流浸食(rill erosionリル･エロージョン)，幾多の細流が地面を覆って広がる布状洪水sheet floodによって土地が全体的に浅く削られる布状浸食sheet erosion，さらに細流が集中して雨裂(雨溝，ガリーgully)を刻むガリー浸食gully erosionが含まれる。雨食が目だって作用するのは火山麓のような緩傾斜面や大陸台地のような平たん面や段丘面などであり，河川の谷頭よりも相対的に上位にあたる場所におこる。…

【土壌浸食】より

…土地への雨滴の衝撃により土壌粒子は分散して泥状となり，土壌表面に緻密（ちみつ）で透水性の不良な層を形成する。このため地下浸透ができなくなった雨水は土壌を懸濁して斜面を流去する(雨滴浸食)。雨水や融雪，融氷水が広い範囲にわたって流去する場合，まず土壌表層が薄い層状に流亡する(面状浸食，表面浸食，層状浸食などという)。…

※「雨滴浸食」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

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