Doctoral Dissertation Research: Quantitative Hydraulic Models for Jokulhlaup-Type Outflow Channels on Mars: Application of Earth Analogues, Geomorphology, and Remote Sensing

对地球类行星的研究主要是用来检验关于可能与地球上的现象相似的现象的假说。这项博士论文研究使用与地球类似的方法来检验这一假设，即火星上巨大的河流水道及其观测到的地貌特征是由地表水流和被冰冻层限制的地下水喷发形成的。这种类型的喷发被称为“Jökulhlap”，这是一个冰岛术语，描述了大量的水从冰川后面或下面突然释放出来。地球表面也有类似的位置，包括华盛顿州东部的切尼-帕卢兹冰原(与冰川湖米苏拉湖有关)和冰岛Vatnajökull冰川的JökulsááFjöllum海峡。这些地球上的类似物是由过去地质上的约库勒劳普型暴发洪水形成的，因此应该提供关于火星上的过程的洞察，那里的源区盆地的大小不足以创造所观察到的河流和地貌特征，特别是考虑到较低的行星引力常数。这项研究包括使用空间遥感、地面实地测量以及对地球和火星上的自然现象进行一维、二维和三维水文和水力模拟。收集和处理遥感数据将提供水文和水力模型所需的河道物理性质，然后将通过对冰川湖密苏拉湖古洪水带和冰岛两个地球模拟研究区的河道进行广泛的实地测绘来验证这一点。将测试一种独特的技术，用于根据基岩的热惯性和传导性来推导表面粗糙度的水力特性。这项工作的目标是估计在地球上建立约库勒劳普型河流和地貌特征所需的平均流速、峰值流量和功率，以便将这些模型应用于火星上的类似河流。其次，目标是在重力常数小于地球重力常数的情况下，定量确定火星形成这些地貌所需的水量。这项研究将为火星的水文和地质史提供新的定量见解。这项工作的结果将传达关于塑造火星河流地貌所需水量的定量信息，并为了解火星过去的地质和水文历史提供重要的数据点。这项研究将对火星上形成大规模流出通道的机制以及气候变化可能如何影响这些过程提供关键的见解。同样，在类似地球的地点，特别是在受冰川过程影响最大的地区，对灾难性的水流状况以及地表和地下水源之间的相互作用进行水文和水力模拟，将为我们自己的气候变化可能发生的过程提供一个观点。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。

Studies of Earth analogues of planetary bodies are used primarily to test hypotheses about phenomena that may be similar to those on Earth. This doctoral dissertation research uses Earth analogues to test the hypothesis that the massive fluvial channels on Mars and their observed geomorphic features were formed by a combination of surface water flow and eruptions from ground water confined by a cryolithospheric layer. These types of eruptions are termed "Jökulhlaup", from an Icelandic term that describes an abrupt release of massive amounts of water from behind or beneath a glacier. There are also similar locations on the Earth's surface, including the Cheney-Palouse Scablands in eastern Washington (associated with Glacial Lake Missoula) and the Jökulsá á Fjöllum channel at Vatnajökull glacier in Iceland. These Earth analogues were formed by jökulhlaup-type outburst floods in the geologic past, and so should provide insights into processes on Mars, where the size of the source basins is not sufficient to create the fluvial and geomorphic features observed, especially given the lower planetary gravitational constant. This research encompasses the use of space-borne remote sensing, ground-based field measurements, and one, two and three-dimensional hydrologic and hydraulic modeling of natural phenomena on Earth and Mars. Collecting and processing remote sensing data will provide the fluvial channel physical properties needed for the hydrologic and hydraulic models, which then will be verified by extensive field mapping of the fluvial channels at two Earth analogue study areas, in the Glacial Lake Missoula paleoflood zone and in Iceland. A unique technique for deriving the hydraulic property of surface roughness, based on bedrock thermal inertia and conductivity, will be tested. The objective of this work is to estimate the mean flow velocity, peak discharge and power needed to create the jökulhlaup-type fluvial channels and geomorphic features on Earth in order to apply these models to similar channels on Mars. Secondly, the goal is to establish quantitatively the amount of water needed on Mars to create these features given a gravitational constant less than half that of the Earth's. This research will provide new quantitative insight into the hydrologic and geologic history of Mars.The results of this work will convey quantitative information about the amount of water needed to sculpt the fluvial landforms on Mars and provide a significant datapoint to its geologic and hydrologic past. This research will provide key insight into the mechanisms that created the massive outflow channels on Mars and how climate change may have influenced these processes. Similarly, hydrologic and hydraulic modeling of catastrophic flow regimes and the interactions between surface and subsurface water sources at Earth analogues sites, particularly at those areas most influenced by glacial processes, will provide a viewpoint to the processes that may occur due to our own climate change. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.