Late Quaternary History of the Walker River: The Tale of a River with a Split Personality

沃克河的晚第四纪历史：一条具有分裂人格的河流的故事肯尼斯·d·亚当斯沙漠研究所内华达州诺市摘要沃克河是流入内华达州西北部拉洪坦盆地和邻近的加利福尼亚州东北部的五条主要河流之一。自晚更新世以来，这条河的行为就很不寻常，因为它不是像今天这样流入沃克湖，而是在全新世期间，有时它会转向流入卡森水槽。当这种情况发生时，沃克湖变成了一个相对干燥的盐湖，而卡森湖则获得了一个重要的新水源。当河流转回沃克湖时，playa被洪水淹没，卡森湖的湖泊可能缩小了。因此，基于两个流域湖泊的行为和状态的古气候重建必须考虑沃克河的改道历史。该项目pi将对自Lahontan湖最后一个高点以来沃克河的行为及其对沃克湖和卡森湖古水文的影响进行综合研究。这项研究对大盆地过去、现在和未来的许多研究工作都具有重要意义。首先，这项研究的结果将有助于检验一个假设，即在最后一个主要湖泊循环之后，快速均衡反弹导致沃克河改变了它的路线。其次，沃克湖流域湖泊水位的波动可能是河流改道的功能，而不是气候波动。第三，在全新世晚期，卡森汇中的大型短命湖泊将人类、动物和植被迁移到卡森汇的外围，这也可能是由于河流改道，而不是气候波动。第四，本研究的结果将作为修正的输入参数，为均衡反弹建模的努力。第五，受威胁的拉洪坦割喉鳟鱼的历史和生存将被置于一个新的视角，这可能有助于恢复工作。这项研究是重建拉洪滩地区过去30万年的古气候和反弹历史的长期努力的一部分。认识到快速均衡回弹可能引发了大规模的地貌和水文效应，这是完善Lahontan湖盆地均衡回弹模型并记录这些影响对该地区古环境史的重要性。拟议的研究结果将导致更完整的盆地古气候记录，也将记录气候变化，地球深部过程和地表过程之间的相互关系。

Late Quaternary history of the Walker River: The tale of a river with a split personalityKenneth D. AdamsDesert Research InstituteReno, NevadaAbstractThe Walker River is one of five major streams that flow into the Lahontan basin of northwestern Nevada and adjacent northeastern California. The behavior of this river since the late Pleistocene is quite unusual because instead of flowing into Walker Lake as it does today, at times during the Holocene it diverted to flow into the Carson Sink. When this happened, Walker Lake became a relatively dry playa whereas the Carson Sink gained a significant new water source. When the river diverted back to Walker Lake, the playa was flooded and lakes in the Carson Sink presumably shrank in size. Paleoclimatic reconstructions based on the behavior and status of lakes in both basins must therefore consider the diversion history of the Walker River.The project-PI will perform an integrated study of the behavior of the Walker River since the last highstand of Lake Lahontan and its effects on the paleohydrology of Walker Lake and the Carson Sink. This research is significant to a host of past, present, and future research efforts in the Great Basin. First, the results of this research will serve to test the hypothesis that rapid isostatic rebound after the last major lake cycle caused the Walker River to change its course. Second, fluctuations of lake levels in the Walker Lake basin may be a function of river diversion, not climatic fluctuations. Third, large short-lived lakes in the Carson Sink that displaced people, animals, and vegetation to the periphery of the Sink in the late Holocene may also be due to river diversion and not climatic fluctuations. Fourth, the results of this research will serve as revised input parameters for isostatic rebound modeling efforts. And fifth, the history and survival of the threatened Lahontan Cutthroat Trout will be placed into a new perspective that may assist recovery efforts.The research is part of a longer-term effort to reconstruct the paleoclimatic and rebound history of the Lahontan region over the last 30 ka. Recognition that rapid isostatic rebound may have invoked large-scale geomorphic and hydrographic effects underlies the importance of refining the isostatic rebound model for the Lake Lahontan basin and documenting these effects on the paleoenvironmental history of the region. The results of the proposed research will lead to a more complete paleoclimatic record from the basin and will also document the interrelationships between climate change, deep Earth processes, and surface processes.