Land & Environment

How Dry Can the Colorado River Basin Get?

Looking to the past's data to better predict the future

Lake Mead's level is dropping under drought conditions ongoing since 2000. (David Tarboton photo)

编者注:本文最初发表于犹他州水研究实验室的通讯. It has been edited lightly for style.

As drought conditions persist in the Colorado River Basin, managers, 研究人员和公众都在想:干旱会有多严重?

At the Utah Water Research Laboratory, 研究生Homa Salehabadi和主管David Tarboton试图通过使用历史干旱数据来预测未来干旱情景下科罗拉多河的流量来回答这个问题. Guided by the idea that if it has happened in the past, it might happen again in the future, 他们发现,未来的干旱条件可能会产生比现在更低的流速. 这表明在科罗拉多河流域需要替代的管理策略.

“The hope is that this research provides easy-to-use, openly available, 为水管理人员评估不同的释放和管理方案而编制的场景,” Tarboton said.

Digging into the Data

To establish the significance of this drought in the history of the river, as well as project potential scenarios for the future, Salehabadi和Tarboton评估了科罗拉多河在亚利桑那州北部李斯渡口的流量. For periods that predate modern measurements of the river, they relied on data from dendrochrolologists who have, through the correlation of tree ring widths with streamflow, been able to reconstruct streamflow back from 1416.

More recent flow rates originate from Lees Ferry, just below Glen Canyon Dam, 由填海局量度流量及计算自然流量的地方. Natural flow is what the flow in the river would be, were it not for upstream diversions, storage and consumptive use. 利用1906年至2021年的数据计算,李斯渡口的平均自然流量为14.67-million-acre feet per year (maf/yr). 然而,使用2000年至2021年的最新观测数据,这一数字下降到了12.3 maf/yr.


Tarboton说:“牛电竞app似乎正处于干旱期,这可能是一种新常态。. “We should expect and plan for lower uses to match reduced supply.”

Typically, the total demand for Colorado River water hovers around 15 maf/yr, while recent annual flows have been closer to 12 maf/yr. 这种赤字已经耗尽了鲍威尔湖和米德湖的供应, which provide about 50 maf of combined storage.

Past and Future Droughts

Looking at tree-ring data, as well as natural flowrates at Lees Ferry, Salehabadi和Tarboton确定了影响科罗拉多河流域的三个主要干旱时期:

  • A paleo tree-ring derived drought from 1576 to 1600, 这个时期的流量下降比历史记录上任何一个时期都要多.
  • The mid-20th century drought from 1953 to 1977.
  • The current drought from 2000 to the present day.

Salehabadi和Tarboton从每一次干旱的记录中随机选择了流量,并为每一次创造了100个序列的低流量情景(痕迹). 每条痕迹都包含了42年科罗拉多河流域的月流量. 这三组轨迹产生的干旱情景从2018年延续到2060年. Salehabadi和Tarboton还将这些模拟结果与预测科罗拉多河未来流量的气候模型进行了比较,并发现, 而来自不同气候模式的气候预估径流显示出相当大的变异性, 随机干旱情景的模拟与气候模式并不矛盾. 这表明他们的模拟可以为科罗拉多河流域提供可信的极端场景.

研究结果得出的结论是,未来的干旱可能会比当前的干旱更严重,并提出需要考虑替代当前管理科罗拉多河模式的方案. 这对供水和水力发电都有影响,因为沿河的水库可能会降到发电所需的最低水位以下. 虽然人们很容易认为,当前的干旱是一种极其罕见的事件,不会引发任何永久性的变化, this research pushes back against that notion. 结果表明,牛电竞app现在认为是暂时的措施可能需要变成永久性的.

Supporting Solutions

Drought research is not new to UWRL and USU researchers. In 1995, 塔博顿是由时任科罗拉多河水资源研究所所长L领导的一项大型多州科罗拉多河严重持续干旱研究的一部分. Douglas James that, based on tree-ring reconstructions, 设想了一个比上个世纪更可怕的供水场景. 目前的情况与当时预见的严重持续干旱十分相似. 这项研究探讨了牛电竞app河流如何运作的制度安排, noting that institutional inflexibility presents a significant challenge.

最近,亚利桑那州立大学的其他人也加入了有关干旱管理的研究. In a series of white papers, 由杰克·施密特领导的USU科罗拉多河研究中心评估了垦殖局模型的准确性, researched alternative management paradigms and streamflow losses, among other topics.

作为讨论的基础,并鼓励解决科罗拉多河日益减少的供应所需的灵活性, UWRL的David Rosenberg开发了一项科罗拉多河流域参与式建模活动,允许参与者探索灵活的水资源会计,以实现可持续的水资源分配解决方案. Thus, while the current drought situation in the Colorado is alarming, 从这些先前和正在进行的研究中可以获得大量基于研究的信息,以帮助水资源管理者克服这些困难.


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