人類による世界の川の沈殿物流の急速な変化
Evan N Dethier1,2, Carl E Renshaw1, Francis J Magilligan3
1Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA.
まとめ
地球上の河川の堆積物量は 人間の活動によって劇的に変化しています 北部のダムでは沈殿物を捕まえて 南部の土地利用は侵食を助長し 沈殿物の源を南米に移動させます
科学分野:
- 環境科学
- 水学
- リモートセンシング
背景:
- 川は生態学的機能,人間の健康,インフラに不可欠です.
- 限られた河川の採取により,世界の河川システムの変化の理解が制限されます.
- 人類の活動が 過去50年間に渡って 世界中の川系に 深刻な影響を及ぼしてきました
研究 の 目的:
- 川の沈殿物濃度と流量の全般的な変化を評価する.
- 観察された変化を特定の人間の活動と結びつける.
- 北と南の沈殿物のダイナミクスの違いを理解する.
主な方法:
- サスペンドされた沈殿物の濃度と流量の衛星ベースの推定値を使用した.
- 414の主要な川のデータを分析しました
- 現在の沈殿物の動態とダム以前の状態と1980年代のデータを比較した.
主要な成果:
- 全球的な堆積物流は,主に地球北部のダムによる堆積物捕獲により,ダム前のレベルの49%まで減少しました.
- 世界南部の土地利用の激しい変化により 侵食が増加し 1980年代以降 川の沈殿物の平均濃度が41%増加しました
- 沈殿物のダイナミクスの重要な南北の分岐は,南米が支配的な源として浮上する海域へのグローバルな沈殿物の流れパターンを再構成しています.
結論:
- 人間の活動,特にダム建設と土地利用の変化は,観測された世界的な河川堆積物の変化の主な要因です.
- この研究は,アジアから南米に移動する世界的な河川の沈殿物の源の重要な変化を強調しています.
- 河川の生態系と沿岸環境の管理には このダイナミクスを理解することが不可欠です
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