Hydrological thresholds in depression storage and contributing area for low-relief landscapes

这项研究是我早期在数字地形分析方面工作的延伸，旨在提高我们对地表凹陷对径流影响的建模能力和理解。加拿大落基山脉以西的低地貌景观的显著特征之一是广泛出现由冰川和冰缘过程产生的浅表凹陷。在加拿大大草原上，这些凹陷通常被称为大草原凹坑或泥坑。它们提供了对环境具有重要意义的湿地，并对河流径流和地下水状况进行了重大控制。地表凹陷的大小和频率在整个景观中可能会有很大的差异。它们通常由排水沟相连，只有当凹地的存储容量被填满时，水才会沿着排水沟流动。从填满的洼地中溢出的水代表着水文阈值的转移，集水区和径流量经常发生巨大变化。南萨斯喀彻温河流域表明了地表凹陷蓄水对区域水文和气候过程的潜在意义，科学家估计，该流域超过50%的地貌很少向主要河流系统提供径流，因为排水沟和坑洞打断了排水路线。这项研究的目标是(1)描述在加拿大大部分地区发现的复杂的凹地间水流模式的主要特征，(2)修改数字地形分析中使用的标准算法，以在局部尺度的水文模型中适当地表示这种模式，以及(3)开发放大技术，以使我们对该系统的更好的理解能够有效地用于区域尺度的水文模型。虽然这项研究将特别侧重于草原景观中地表凹陷的水文影响，但其成果也将应用于加拿大盾和北部冻土带等地区，这些地区的地表凹陷也是景观的重要元素。

This research is an extension of my earlier work in digital terrain analysis and aims to improve our understanding and ability to model the impact of surface depressions on streamflow. One of the distinctive features of the low-relief landscapes of Canada west of the Rocky Mountains is the wide-spread occurence of shallow, surface depressions produced by glacial and periglacial processes. In the Canadian Prairies, these depressions are often called Prairie potholes or sloughs. They provide environmentally-important wetland sites and exert a significant control on streamflow and groundwater regimes. The size and frequency of surface depressions can vary greatly across the landscape. They are often linked by drainage courses along which water flows only when the storage capacity of the depressions is filled. Water spilling from filled depressions represents a hydrological threshold shift with catchment areas and streamflow volumes often changing dramatically. The potential significance of surface depression storage to regional hydrologic and climatic processes is illustrated by the South Saskatchewan River Basin where scientists estimate that over 50% of the landscape rarely contributes runoff to the major river system because of the interuption of drainage courses by sloughs and potholes. The objectives of this research are to (1) characterize the major features of the complex, inter-depressional flow patterns found in much of the Canadian Praires, (2) modify the standard algorithms used in digital terrain analysis to appropriately represent this pattern in local-scale hydrological models and (3) develop up-scaling techniques to allow our improved understanding of this system to be used effectively in regional scale hydrological models. While this research will focus particularly on the hydrological impact of surface depressions in Prairie landscapes, its outcomes will also have application in areas like the Canadian Shield and northern tundra where surface depressions are also an important element of the landscape.