US-Egypt Cooperative Research: Improved Hydrogeophysical Assessment of Recharge Beneath Ephemeral Streams and Applications in Arid Areas

0322548 Ferre描述：该奖项是为了表彰由亚利桑那州图森市亚利桑那大学水文地质和水资源系Paul Ferre博士和埃及开罗国家研究中心地质和地球物理系Hesham El-Kaliouby博士共同开展的一项研究项目。这项研究的目的是：1)应用非破坏性的地球物理方法监测短暂河流下整个包气带的水储量变化；2)确定河床入渗、地下再分配和补给之间的时间关系；3)描述这些关系，以便在水文模型中改进对河床补给的表示。这两位科学家将开发野外地球物理方法来量化短暂溪流下的补给。这一数据集将提供一个独特的机会，通过厚厚的包气带校准瞬时非饱和流动模型，从而更好地了解短暂溪流下的水运动。测量数据将使用非侵入性地面时间域电磁仪进行采集。在用数值模型对现场测量数据进行解释的基础上，建立了一个简化的河床补给概念模型。这种对干旱地区地下水文学的描述对于确定补给的时空分布，以便用于可持续发展规划至关重要。范围：干旱和半干旱地区的可持续发展只能通过在流域范围内建立可持续的水收支来实现，而这有赖于对补给的更好的、定量的了解。对于许多半干旱环境，短暂河流下的补给在总补给中占主导地位；然而，这一主题得到的研究很少。对短暂河流下的补给进行定量研究所面临的最困难的挑战之一是需要对超过50米的深度进行准确、详细的水文测量。目前测量含水率或基质势的方法有限，实际测量的深度分辨率和最大深度有限，而根据岩心测量的水力传导度剖面既耗时又昂贵。因此，现有的方法无法监测干旱和半干旱地区典型的深层包气带的整个厚度的这些特性。这项工作的意义在于将水文学和地球物理学结合起来，导致目前无法对补给量进行量化的关键测量。这项工作应该导致更有效的水规划，可以通过这些改进的补给估计来实现。该项目的资金由国际科学和工程办公室和地球科学司提供。

0322548 FerreDescription: This award is for support of a joint research project by Dr. Paul Ferre, Department of Hydrogeology and Water Resources, University of Arizona, Tucson, Arizona and Dr. Hesham El-Kaliouby, Department of Geology and Geophysics, the National Research Center, Cairo, Egypt. The purpose of the research is: 1) to apply nondestructive, geophysical methods to monitor changes in water storage throughout the vadose zone beneath an ephemeral stream; 2) to determine the temporal relationships between streambed infiltration, subsurface redistribution, and recharge; and 3) to describe these relationships in a manner that will allow for improved representation of streambed recharge in hydrologic models. The two scientists will develop field geophysical methods for quantifying recharge beneath ephemeral streams. This data set will provide a unique opportunity to calibrate a transient unsaturated flow model through a thick vadose zone, leading to improved understanding of water movement beneath ephemeral streams. Measurements will be collected with noninvasive surface time domain electromagnetic instrument. A simplified conceptual model of streambed recharge will be developed based on interpretations of the field measurements with numerical models. This description of the subsurface hydrology of arid regions is critical to define the spatial and temporal distributions of recharge for use in sustainable development planning. Scope: The sustainable development of arid and semi-arid regions can be achieved only through the establishment of a sustainable water budget at the basin scale, which depends on an improved, quantitative understanding of recharge. For many semi-arid environments, recharge beneath ephemeral streams dominates total recharge; however, this topic has received little study. One of the most difficult challenges facing a quantitative study of recharge beneath ephemeral streams is the need to make accurate, detailed hydrologic measurements to depths in excess of 50 meters. Current methods of measuring the water content or matric potential have limited depth resolution and maximum depths of practical measurement, while profiling the hydraulic conductivity from measurements on soil cores is time consuming and expensive. As a result, existing methods are incapable of monitoring these properties over the entire thickness of the deep vadose zones that are typical in arid and semi-arid regions. The significance of this work lies in the convergence of hydrology and geophysics leading to critical measurements that cannot currently be made to quantify recharge. This work should lead to a more efficient water planning that can be achieved with these improved recharge estimates. Funding for this project is provided by the Office of International Science and Engineering and the Division of Earth Sciences.