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的工作的延伸，旨在提高我们对地表凹陷对径流影响的理解和建模能力。加拿大落基山脉以西低起伏地形的显著特征之一是广泛存在由冰川和冰缘过程产生的浅地表凹陷。在加拿大大草原，这些洼地通常被称为草原坑洞或泥沼。它们提供了重要的环境湿地，并对径流和地下水系统产生重要的控制作用。地表凹陷的大小和频率在整个地貌中可能差异很大。这些洼地通常由排水道沿着连接，只有当洼地的蓄水能力被填满时，水才会流动。水溢出填补洼地代表了水文阈值的变化与集水区和径流量往往发生显着变化。表面凹陷存储区域水文和气候过程的潜在意义是由南萨斯喀彻温河流域，科学家估计，超过50%的景观很少贡献径流的主要河流系统，因为由泥沼和坑洼的排水过程的interuption说明。这项研究的目标是（1）描述加拿大大部分地区复杂的、凹陷间流动模式的主要特征，（2）修改数字地形分析中使用的标准算法，以便在局部尺度水文模型中适当地表示这种模式;（3）开发-尺度技术，使我们更好地了解这个系统，有效地用于区域尺度水文模型。虽然这项研究将特别侧重于在草原景观的表面凹陷的水文影响，其结果也将有应用在加拿大地盾和北方苔原等地区的表面凹陷也是景观的一个重要元素。

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.