Paleohydrologic Controls on Alluvial Deposition: A Process-Simulation Approach to Reconstruct Aquifer Heterogeneity

物理过程模拟可以用来帮助重建沉积物的空间格局，其中包括用于供水的含水层。沉积演化是使用基于大规模数学的过程模拟模型来模拟的，该模型描述了数十万年来发生的水文、沉积和构造事件。感兴趣的具体过程是大洪水、沉积、侵蚀、压实、下沉、海平面变化和区域尺度的断层运动。该产品也是一种定量研究含水层地层学及其与古水文学和构造条件的演化联系。该仪器可用于对相对流动路径和流动障碍的大规模模式非常重要的水文地质调查。应用的领域是加利福尼亚州北部的圣克拉拉山谷，那里大约240-2地下水提供了圣克拉拉山谷大约一半的公共供水，但抽水造成了由于粘土压实而造成的严重地面沉降问题。在大多数地区，对含水层非均质性和限制层几何形状对地下水流动和地面沉降的控制知之甚少。该山谷位于海沃德-卡拉维拉斯和圣安德烈亚斯断层系统交界的地块内的一个构造凹陷内。分别进行了分析。多含水层系统由相互交错的冲积扇和过去60万年形成的河口沉积组成。沉积过程模拟模型的结果将与覆盖山谷某些部分的地质和水文地质数据进行比较。其目的是利用该模型来解释过去各种水文和地质过程在冲积湾含水层结构发展中所起的作用。

0207177Gorelick.Physical process simulation can be used as a too] to help reconstruct the spatial pattern of sediments comprising aquifers used for water supply. Sedimentary evolution is simulated using a process-imitating model, based on large-scale mathematics, that describes hydrologic, sedimentary, and tectonic events which have occurred over hundreds of thousands of years. The specific processes of interest are major floods, sedimentation, erosion, compaction, subsidence, sea-level variation, and regional-scale fault motion. The product is a quantitative too] to study aquifer stratigraphy and its evolutionary link to paleohydrology and tectonic conditions. This tool can be used in hydrogeologic investigations where the large-scale pattern of relative flow paths and flow barriers is important.The field area for application is the Santa Clara Valley in northern California, which is Approximately 240 mi2 Groundwater provides approximately half of the public water supply in Santa Clara Valley, yet pumping has caused a serious problem of land subsidence due to clay compaction. In most areas, the controls on groundwater flow and land subsidence imposed by aquifer heterogeneity and confining bed geometry are poorly understood. The Valley occupies a structural depression within a block bounded on the cast and west by the Hayward-Calaveras and San Andreas Fault systems. Respectively. The multiaquifer system consists of coalescing alluvial fans interfingered with estuarine deposits that have been formed over the past 600,000 years. The sedimentary process simulation model results will be compared to geologic and hydrogeologic data covering certain portions of the Valley. The goal is to use the model to interpret the roles played by various past hydrologic and geologic processes on the development of alluvial-bay aquifer architecture.