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リオグランデ川流域における持続不可能な水利用を明らかに(Study finds unsustainable water use across the Rio Grande)

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2025-11-21 バージニア工科大学(Virginia Tech)

ライグランデ(米墨国境を流れる大河)流域において、水の消費量が自然に再び補給される量を大きく上回っており、流域の水資源が持続不可能な状態にあるという研究が、Virginia Techの研究者らによって示されました。具体的には、流域内の総水消費のうち、約48%しか再生可能な水量によって賄われておらず、残りの52%が貯水池や地下水、流れそのものを枯渇させていると推定されています。農業灌漑が直接消費の87%を占め、蒸発・植生による間接消費も大部分を占めています。こうした過剰利用は貯水池の貯量低下、地下水位の減少、そして一部では河川の枯渇という形で顕在化しており、流域に暮らす何百万人もの都市住民・農業者・生態系にとって深刻な脅威です。研究では、水資源管理・農業用水構成の見直し・緊急な越境協力が必要であると結論づけられています。

リオグランデ川流域における持続不可能な水利用を明らかに(Study finds unsustainable water use across the Rio Grande)
The Rio-Grande Bravo Basin. Map courtesy of Landon Marston.

<関連情報>

過剰消費は二国間リオグランデ・ブラボー流域の水安全保障を深刻に脅かしている Overconsumption gravely threatens water security in the binational Rio Grande-Bravo basin

Brian D. Richter,Karem Abdelmohsen,Sameer Dhakal,James S. Famiglietti,Kat F. Fowler,Henry Green,Landon Marston,Mesfin M. Mekonnen,Enrique Prunes,Melissa M. Rohde,Benjamin L. Ruddell,Richard R. Rushforth,Natalie Shahbol,Eric C. Sjöstedt & Samuel Sandoval-Solis
Discover Water  Published:20 November 2025
DOI:https://doi.org/10.1007/s43832-025-00301-2

Abstract

The Rio Grande-Bravo basin shared by the United States and Mexico is experiencing a severe water crisis demanding urgent attention. In recent decades, water storage reservoirs, aquifers, and annual streamflow volumes have been substantially depleted, leaving little buffer for continued over-consumption of renewable water supplies. Despite the great scarcity of water and intensifying water shortages in this basin, a full accounting of the river’s consumptive uses and losses has never been undertaken. In this study we assemble detailed water consumption estimates from a broad array of sources to describe how surface and ground water were consumed for both direct uses (agricultural, municipal, commercial, thermoelectric power generation) and indirect uses (reservoir evaporation and riparian evapotranspiration) in each of 14 sub-basins during recent decades. We estimate that only half (48%) of water directly consumed for anthropogenic purposes is supported by renewable replenishment; the other half (52%) has been unsustainable, meaning that it is causing depletion of reservoirs, aquifers, and river flows. The over-consumption of renewable water supplies is primarily due to irrigated agriculture, which accounts for 87% of direct water consumption in the basin. At the same time, water shortages have contributed to the loss of 18% of farmland in the river’s headwaters in Colorado, 36% along the Rio Grande in New Mexico, and 49% in the Pecos River tributary in New Mexico and Texas. Farmland contraction in the US portion of the basin has resulted in lowered irrigation consumption and many cities have been able to reduce their water use as well, but irrigation in the Mexican portion of the basin has increased greatly, causing basin-wide consumption to remain high. This severe water crisis presents an opportunity for envisioning a more secure and sustainable water future for the basin, but a swift transition will be needed to avoid damaging consequences for farms, cities, and ecosystems.

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0803資源循環及び環境
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