湖の水量減少の原因を特定する研究 Study identifies cause of lake’s water loss
2022-10-06 カリフォルニア大学リバーサイド校(UCR)
The shore line of the Salton Sea taken from the Salton Sea State Recreation Area. (Stan Lim/UCR)
湖が干上がるにつれて、残った水に含まれる塩分や化学物質の濃度が急激に高まり、絶滅危惧種を含む魚や鳥が大量に死滅している。塩分を含んだ有毒な水でコーティングされた乾燥した湖底は、塵となって周辺住民に呼吸器系の問題を引き起こしている。
世界中の内水面湖は、地球温暖化と農業・工業用水への転換の複合的な影響により、研究者が「憂慮すべき」速度でここ数十年の間に縮小している。
研究者たちは、ソルトン湖の減少の理由を理解するために、気候、土壌の種類、土地の傾斜、植物の成長など、湖の水収支に影響を与える周辺地域のすべてのプロセスを考慮した水文学モデルを使用した。
UCRの研究者は、一般に公開されているデータとデータマイニング技術を使用して、長期的な水収支の動態をシミュレーションし、コロラド川の流量減少がソルトン湖縮小の主な原因であると特定することに成功した。
＜関連情報＞
- https://news.ucr.edu/articles/2022/10/06/why-salton-sea-turning-toxic-dust
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022WR032281
高度に管理された越境流域における主要な水文変動要因の同定：水文生態系モデルと時系列データマイニングの融合 Identifying Major Hydrologic Change Drivers in a Highly Managed Transboundary Endorheic Basin: Integrating Hydro-Ecological Models and Time Series Data Mining Techniques
Juan S. Acero Triana,Hoori Ajami
Water Resources Research Published: 23 August 2022
DOI:https://doi.org/10.1029/2022WR032281
Abstract
The fragile balance of endorheic lakes in highly managed semiarid basins with transboundary water issues has been altered by the intertwined effects of global warming and long-term water mismanagement to support agricultural and industrial demand. The alarming rate of global endorheic lakes’ depletion in recent decades necessitates formulating mitigation strategies for ecosystem restoration. However, detecting and quantifying the relative contribution of causal factors (climate variability and anthropogenic stressors) is challenging. This study developed a diagnostic multivariate framework to identify major hydrologic drivers of lake depletion in a highly managed endorheic basin with a complex water distribution system. The framework integrates the Soil and Water Assessment Tool (SWAT) simulations with time series decomposition and clustering methods to identify the major drivers of change. This diagnostic framework was applied to the Salton Sea Transboundary Basin (SSTB), the host of the world’s most impaired inland lake. The results showed signs of depletion across the SSTB since late 1998 with no significant changes in climate conditions. The time series data mining of the SSTB water balance components indicated that decreases in lake tributary inflows (−16.4 Mm3 yr−2) in response to decline in Colorado River inflows, associated with state water transfer agreements, are causing the Salton Sea to shrink, not changes in the irrigation operation as commonly believed. The developed multivariate detection and attribution framework is useful for identifying major drivers of change in coupled natural human systems.
Key Points
- Quantifying relative contribution of climate and anthropogenic stressors in water budget of managed endorheic basins is challenging
- Time series decomposition approaches identify key water balance variables responsible for endorheic lake depletion
- Clustering of decomposed time series reveals structural behavior of water balance components and trace sources of system alterations
