Collaborative Research: River Stage Tomography for Automatic Characterization of Fluxes between Surface and Groundwater Reservoirs: A Pilot Study

准确了解水和化学物质平衡是正确管理流域水资源的关键。 经过几十年的实地调查和建模，地下水储量，地表和地下水库之间的通量，以及地表和大气之间的通量在流域/分水岭仍然是高度不确定的。 要解决这个问题，需要在表征、监测和建模方法上取得突破。在这项建议中，我们提出了一种新的水力层析成像方法来表征，监测和预测的潜流区及以后，使用时空变化的河流阶段和相应的地下水附近的河流响应。 这项新技术可以进行三维成像，确定河流/地下水边界的通量，并以目前尚不可行的方式对潜流和地下系统进行表征。 如果这项拟议的概念验证研究取得成功，该技术最终可以扩展到流域/流域规模的问题。这项研究的目的是证明，水力层析成像的基础上，河流水位波动是一个有效的概念和一个可行的技术，用于检测大规模的地下非均质性附近的河流。 我们打算表明，这一概念和技术可以在与河流相互作用的无压含水层中实现其目标。 拟议的任务包括：1）改进现有的水文层析成像反演算法，使之适应时空变化的边界条件，即时空变化的河流水位：2）通过数值模拟研究时空变化的河流水位对人工非均质潜水含水层地下水位的影响; 3）在改进的反演算法中使用这些模拟的井过程线来测试其检测潜流带内的非均匀性的能力;和4）的方法利用两个现有的砂箱进行实验室研究，砂箱中有一个合成的非均质非承压含水层。研究结果应表明，由于河流水位在时间和空间上变化很快，因此，只要能够很好地描述河流水位的变化，层析反演就是一种有效和合理的方法。

The accurate knowledge of water and chemical mass balances is the key to proper management of water resources in a watershed. After decades of field investigations and modeling, groundwater storage, fluxes between surface and subsurface reservoirs, and fluxes between land surface and atmosphere over a basin/watershed still remain highly uncertain. A breakthrough in characterization, monitoring, and modeling approaches is needed to resolve this issue. In this proposal, we propose a novel hydraulic tomography approach to characterize, monitor, and predict the hyporheic zone and beyond, using spatial-temporal variations in river stages and the corresponding groundwater responses near a river. This new technology allows three-dimensional imaging and determination of fluxes across the river/groundwater boundaries and characterization of the hyporheic and subsurface system in a manner that is presently not feasible. If this proposed proof-of-concept study is successful, the technology can ultimately be extended to basin/watershed scale problems. The goal of the study is to demonstrate that hydraulic tomography based on river stage fluctuations is a valid concept and a viable technology for detecting large-scale subsurface heterogeneity near the river. We intend to show that the concept and technology can accomplish its goal in unconfined aquifers that interact with rivers. Proposed tasks include: 1) the modification of existing hydrologic tomography inversion algorithm to accommodate temporally and spatially varying boundary conditions, which represent the temporally and spatially varying river stages; 2) the examination of the effects of temporal and spatial varying river stage on groundwater level in synthetic heterogeneous unconfined aquifers through numerical simulations; 3) the use of these simulated well hydrographs in the modified inversion algorithms to test its ability to detect heterogeneity within the hyporheic zone; and 4) the conduct of laboratory studies using two existing sandboxes with a synthetic heterogeneous unconfined aquifer.Results from the study should demonstrate that while river stages may change rapidly in time and space, the tomographic inversion is a valid and logical approach as long as the variation of the river stages is well characterized.