Integrated Modeling of Groundwater, Unsaturated Zone, and Surface Hydrologic Processes Over Prairie Topography

9703997 Salvucci本提案中描述的研究涉及复杂地形上水文通量的空间结构和缩放特性。它的目的是测试的假设，在一定的地质和气候条件下，水文通量的空间结构控制的双向耦合的地面和地表水过程地形的约束。空间结构的问题将使用最近的进展，了解和模拟之间的相互作用的长期规模的地下水流和短期规模的地面水文过程（Salvucci和EntekloveWRR，30（10），2737-2749，1994年; WRR，31（7），1725-1739，1995年）。这些研究表明，在理论上可以通过等效稳态水分剖面（将长期平均补给量传输到饱和区或从饱和区排出的稳态水分剖面）来参数化浅层地下水和地表通量之间的包气带相互作用。这种简化的耦合代表了地下水深度和近地表土壤水分之间的关键反馈，这反过来又对事件时间尺度的蒸散和产流产生了强烈的影响。通过这种反馈和长期平均连续性的声明，平衡地表水平衡，地下水位深度和地下水分歧是唯一相关的。在这里，这种技术将被应用到一系列的地下水模拟实验，在加拿大托特，1966年研究草原景观。数值实验将被用来作为一种手段，测试是否观测到的空间格局的补给，中线和放电可以解释的耦合表示的等效稳定的水分剖面。如果在这里和未来的研究中得到验证，这种方法将提供一个易于处理的方式来概念化某些地下水-地表水的相互作用和一个实际的替代目前的做法的先验规范的补给和排放区域的区域地下水建模。对于这个网站的影响，自然发生的子山坡长度尺度的补给，中线和流量的水文通量的缩放将进行研究。对这些问题的科学认识的进展直接影响到实际问题，包括土壤湿度遥感估计的空间分解和数值气候模式中次网格尺度陆面通量的参数化。

9703997 Salvucci The research described in this proposal addresses the spatial structure and the scaling properties of hydrologic fluxes over complex topography. It is designed to test the hypothesis that under certain geologic and climatic conditions, the spatial structure of hydrologic fluxes is controlled by the two-way coupling of ground- and surface-water processes as constrained by topography. The issue of spatial structure will be addressed using recent advances into the understanding and modeling of interactions between long time scale groundwater flow and short time scale surface hydrologic processes (Salvucci and Entekhabi WRR, 30 (10), 2737-2749, 1994; WRR,31 (7), 1725-1739, 1995 ). These studies demonstrated that the vadose zone interactions between shallow groundwater and surface fluxes can in theory be parameterized by the equivalent steady-state moisture profile (the steady moisture profile which transmits the long term mean recharge to or discharge from the saturated zone.) This simplified coupling represents the critical feedback between the depth to groundwater and the near surface soil moisture, which in turn has a strong influence on event time scale evapotranspiration and runoff generation. Through this feedback and a statement of long-term mean continuity, the equilibrium surface water balance, water table depth, and groundwater divergence are uniquely related. Here this technique will be applied to a series of groundwater simulation experiments over a well-studied prairie landscape in Canada Toth, 1966 . The numerical experiments will be used as a means of testing whether or not the observed spatial patterns of recharge, midline and discharge can be explained by the coupling expressed by the equivalent steady moisture profile. If verified here and in future studies, this approach would offer both a tractable way of conceptualizing certain groundwater-surface water interactions and a practical alternative to the current practice of a priori specification of recharge and discharge areas in regional groundwater modeling. For this site the influence of naturally occurring sub-hillslope length scales of recharge, midline and discharge on the scaling of hydrologic fluxes will be studied. Prgogress in the scientific understanding of these issues has direct impact on practical problems involving the spatial disaggregation of remotely sensed estimates of soil moisture and the parameterization of subgrid scale land surface fluxes in numerical climate models.