RAPID: How Critical Zone Processes Mediate the Impacts of Severe and Sustained Drought

RAPID：关键区域过程如何调节严重和持续干旱的影响

• 批准号: 2141763
• 负责人: William Dietrich
• 金额: $ 5万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2022-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2141763&HistoricalAwards=false
• 关键词: RAPID; How; Critical; Zone; Processes

The extreme heat wave and drought that is currently gripping the western United States is unprecedented, having led to record-high temperatures and/or record-low precipitation volumes across large geographic areas. The ongoing “megadrought” has been described as the West’s driest period at least 1200 years, having enormous societal consequences. This project rapidly mobilizes to characterize the impacts of the unprecedented and severe drought conditions, where there is a unique opportunity to observe hydrological responses during this event. It explores how three watersheds in northern California respond to prolonged drought. Water storages will be measured during the drought in soils, underlying weathered rocks, groundwater, and stream water, and compared with long-term records of observation under other climatic conditions. The study will reveal how moisture storage in the critical zone (which extends from the vegetation top, through the soil and the underlying weathered bedrock to fresh bedrock) mediates the effects of droughts, and the consequences for stream flow and vegetation survival. Results will be shared with the scientific community and with local stakeholders. The research takes place at the Eel River Critical Zone Observatory in northern California, which is equipped with instrumentation to observe coupled hydrological, ecological, and geological processes. The study will identify how watersheds respond to multi-year drought and wet season shortening, patterns that are predicted for California’s future. Seasonal depletion of rock moisture (moisture stored in the weathered bedrock) by plants leads to a delay in the onset of winter runoff as the first rains restore moisture levels before passing subsequent rains to recharge and runoff. It is hypothesized that forest resilience to drought in summer dry environments depends on the annual rainfall relative to the subsurface moisture storage capacity. The current drought presents a new opportunity to test storage capacity hypotheses because the winter rains ended months earlier, initiating subsurface draw-down sooner, effectively extending the summer dry period. Field sampling campaigns will be conducted to measure water storages at selected locations representing variable critical zone properties, spanning a range of conditions and potential drought sensitivity. The exceptionally dry conditions facilitate sampling of the oldest, least mobile waters released to streams and trees. Using these new data, hypotheses will be tested about the sensitivity of water storage to the style of climate variability predicted in California, informing how watersheds respond to drought.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

目前正在磨削美国西部的极端热浪和干旱是前所未有的，这导致了大型地理区域的高温和/或创纪录的低降水量。持续的“巨型”被描述为西方最干燥时期至少1200年，具有巨大的社会后果。该项目迅速动员起来表征前所未有且严重的干旱条件的影响，在此事件中，有一个独特的机会观察水文反应。它探讨了北加州的三个流域如何应对长期的干旱。在干旱期间，将在土壤，潜在的风化岩石，地下水和溪流水中测量水矿藏，并将其与其他气候条件下的长期观察记录进行比较。该研究将揭示关键区域中的水分储存（从植被顶部延伸到土壤和底层风化的基岩到新鲜基岩）如何介导干旱的影响，以及对河流流量和植被存活的后果。结果将与科学界和当地利益相关者共享。这项研究在北加州的鳗鱼河关键区天文台进行，该天文台配备了仪器，可观察水文，生态和地质过程。该研究将确定流域如何应对多年的干旱和潮湿的季节缩短，这些模式预测了加利福尼亚的未来。植物的季节性部署岩石水分（储存在风化的基岩中）会导致冬季径流发作延迟，因为第一大雨在经过后续的降雨中恢复了水分水平，以补给和径流。假设在夏季干旱环境中，森林对干旱的韧性取决于相对于地下水分储能能力的年降雨量。当前的干旱为测试存储容量假设提供了新的机会，因为几个月前冬季降雨已经结束，从而开始了地下绘制，从而有效地延长了夏季干燥时期。将进行现场采样活动，以测量代表可变临界区特性的所选位置存储，涵盖一系列条件和潜在的干旱敏感性。异常干燥的条件促进了释放到溪流和树木的最古老的移动水域的采样。使用这些新数据，将测试假设对加利福尼亚预测的气候变异性的敏感性的敏感性进行测试，并告知流域对干旱的反应。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子和更广泛影响的审查标准来通过评估来通过评估来获得的支持。

项目成果

Bedrock Vadose Zone Storage Dynamics Under Extreme Drought: Consequences for Plant Water Availability, Recharge, and Runoff

极端干旱下基岩渗流带存储动态：对植物水可用性、补给和径流的影响

• DOI: 10.1029/2021wr031781
• 发表时间: 2022
• 期刊: Water Resources Research
• 影响因子: 5.4
• 作者: Hahm, W. J.;Dralle, D. N.;Sanders, M.;Bryk, A. B.;Fauria, K. E.;Huang, M. H.;Hudson‐Rasmussen, B.;Nelson, M. D.;Pedrazas, M. A.;Schmidt, L.
• 通讯作者: Schmidt, L.