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

9703997 Salvucci本提案所描述的研究涉及复杂地形上水文通量的空间结构和尺度特性。它的设计是为了验证在一定的地质和气候条件下，水文通量的空间结构是由地面和地表水过程的双向耦合控制的，受地形的限制。空间结构问题将利用对长时间尺度地下水流动和短时间尺度地表水文过程之间相互作用的理解和建模的最新进展加以解决(Salvucci和Entekhabi水资源研究，30 (10),2737-2749,1994；水利学报，31(7),1725-1739,1995)。这些研究表明，浅层地下水与地表通量之间的渗透带相互作用在理论上可以用等效稳态水分剖面（传递长期平均补给或从饱和区排出的稳定水分剖面）来参数化。这种简化的耦合代表了地下水深度和近地表土壤湿度之间的临界反馈，而这反过来又对事件时间尺度的蒸散发和产流有很强的影响。通过这种反馈和长期平均连续性的陈述，平衡地表水平衡、地下水位深度和地下水散度是唯一相关的。在这里，这项技术将被应用于一系列地下水模拟实验，这些实验是在1966年加拿大的一个经过充分研究的草原景观上进行的。数值实验将用来检验观测到的补给、中线和放电的空间格局是否可以用等效稳定水分剖面所表示的耦合来解释。如果在这里和未来的研究中得到验证，这种方法将提供一种易于处理的概念化某些地下水-地表水相互作用的方法，并提供一种实际的替代方法，以取代目前在区域地下水模拟中对补给和排放区域进行先验规范的做法。针对该场地，将研究自然形成的补给、中线和流量亚坡长度尺度对水文通量尺度的影响。对这些问题的科学认识的进展直接影响到涉及土壤湿度遥感估算的空间分解和数值气候模式中亚网格尺度地表通量的参数化等实际问题。

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.