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Über dieses Buch

Permafrost Hydrology systematically elucidates the roles of seasonally and perennially frozen ground on the distribution, storage and flow of water. Cold regions of the World are subject to mounting development which significantly affects the physical environment. Climate change, natural or human-induced, reinforces the impacts. Knowledge of surface and ground water processes operating in permafrost terrain is fundamental to planning, management and conservation. This book is an indispensable reference for libraries and researchers, an information source for practitioners, and a valuable text for training the next generations of cold region scientists and engineers.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

The common perception of the world’s cold regions are those inhospitable frigid zones extending outward from the north and south poles that are covered (at least for part of the year) with ice and snow, and where one may expect to find vast expanses of frozen ground, glaciers, ice caps, frozen lakes and ice-covered seas. Further away from the poles, climatic conditions generally become less severe, and the ice and snow may disappear for large parts of the year. This advance of milder conditions with decreasing latitude does not occur uniformly, however, being strongly affected by factors such as surface elevation and large scale atmospheric and oceanic circulations. Thus, latitude alone is not the most useful of markers for the boundary between the cold regions and the temperate zones of the mid-latitudes, where sub-zero temperatures occur infrequently. For this reason, researchers have sought a more comprehensive definition of a cold region on the basis of measurable criteria. Since by far the greater part of the Earth’s land mass and population are found in the Northern Hemisphere, the northern cold regions have received much of the attention.
Ming-ko Woo

Chapter 2. Moisture and Heat

Under a cold climate, water exists in solid, liquid and gaseous states at, above and below the surface. Water can undergo change of state on time scales that vary from hours to days and seasons, to multi-year periods. Phase change involves energy and thus energy balance plays a major role in the detention or the release of water to runoff and river flow. Hinzman et al. (1991) stated that the thermal and moisture regimes are closely related to each other and to the characteristics of the active layer and therefore have a marked influence on permafrost dynamics. This chapter reviews briefly the fundamentals of moisture and heat fluxes at the atmospheric boundary layer and below-ground.
Ming-ko Woo

Chapter 3. Groundwater

Subsurface water is found in saturated and non-saturated zones in the ground. Groundwater is water that occurs in the zone of continuous saturation. Depending on its origin, groundwater can be meteoric water derived from the atmosphere through precipitation, juvenile water produced from within the Earth and brought to the surface by geothermal or volcanic activities, or connate water which is very ancient water trapped in sedimentary rocks when they were deposited.
Ming-ko Woo

Chapter 4. Snow Cover

Snow hydrology is a mature research subject that has long been studied in all world cold regions. Snow is a common feature in temperate and circumpolar latitudes, as well as on high mountains of the tropics (Fig. 4.1). Owing to their high latitude positions, areas of continuous permafrost have at least 250 days of snow cover while discontinuous permafrost zones have over 200 days with snow. Alpine permafrost areas in Tibetan Plateau and in North America have similarly long snow duration. In this chapter, only a synopsis of snow-related processes is presented, with attention focused on the extreme frigid zones.
Ming-ko Woo

Chapter 5. Active Layer Dynamics

The annually frozen and thawed active layer in permafrost terrain and the seasonally frozen ground in non-permafrost areas have comparable thermal and hydrologic behavior for most parts of the year. Pervasive coldness of the winter freezes the near-surface zones of rocks and soils, minimizing the thermal and hydrologic differences between the permafrost and non-permafrost materials. When seasonal frost disappears in the summer, the non-permafrost soil has above-freezing conditions throughout its profile while the active layer continues to be underlain by frigid permafrost with limited permeability. The continued existence of a cold and relatively impermeable substrate is responsible for a set of hydrologic conditions unique to the permafrost environment (Sect. 1.4.1).
Ming-ko Woo

Chapter 6. Slope Processes

Slopes provide hydrologic linkage, through lateral runoff, between uplands and the valleys and plains below. Slope runoff mechanisms vary widely, the result of a host of factors that include permafrost conditions, regional and local climates, topography, soil and vegetation. Snow is a major consideration in generating runoff in cold regions. Not all slopes yield runoff and those that do often exhibit marked seasonal flow rhythms. Investigation of slope hydrology requires information on water supply, storage and loss, flow paths and connectivity with rivers, wetlands and lakes. This chapter describes the pathways of slope runoff in relation to rainfall, snow condition and the permafrost landscape. The sources and delivery of runoff are considered, together with case studies that exemplify slope hydrology in continuous and discontinuous permafrost regions.
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Chapter 7. Cold Lakes

Cold regions are richly endowed with lakes, the occurrence of which may or may not be related to the presence of permafrost. Lakes are maintained when long-term cumulative inputs exceed losses so that there is always enough storage to maintain a water body, at least for most of the time in most parts of the lake. Thus, the capacity and changing status of storage are of crucial importance to lake hydrology. In addition, lake hydrology in cold regions is strongly influenced by the seasonal presence of an ice cover which affects heat and moisture exchanges with the atmosphere and modifies water circulation in the lake.
Ming-ko Woo

Chapter 8. Northern Wetlands

Wetlands and lakes share one common trait: an abundance of surface water during most of the thaw season. Wetlands are lands saturated long enough during the growing season to allow the development of hydric soil, or the support of hydrophytes or prolonged flooding (Cowardin et al. 1979, National Wetland Working Group 1988). Many wetlands contain ponds, and lakes may be fringed by wetlands. Water level and surface area of water bodies within a wetland can vary considerably between wet and dry periods, rendering it difficult to apply water depth or areal extent as the criterion for distinguishing between ponds and small lakes. An arbitrary distinction is made here for convenience of presentation: ponds as parts of a wetland are considered as water bodies with a maximum depth <2 m during the open water season. Wetlands occur where water gains exceed water losses, producing an excess of water that is stored both above and underground, and a water table that often rises above the wetland surface. Vast tracts of wetland are found in permafrost regions of Russia, Canada and Alaska, and wetlands are frequently encountered in other permafrost areas such as the Tibetan Plateau (Fig. 8.1). Although not preferred in this book, the term muskeg (of Algonquin Indian origin) is used in North America literature and applies to peatlands (Radforth and Brawner 1977).
Ming-ko Woo

Chapter 9. Rivers in Cold Regions

River forms and processes have reciprocal feedbacks: the former influence the conveyance of flow and the latter modify channel morphology and drainage pattern. Climate provides the external forcing on the land, driving the hydrologic and fluvial systems to impact streamflow and sediment regimes and the alluvial morphology (Woo and McCann 1994). The relationship between the climate, the hydrologic and the fluvial systems is shown schematically in Fig. 9.1.
Ming-ko Woo

Chapter 10. Basin Hydrology

A drainage basin is a most natural hydrologic unit. Guided by topography, a drainage divide separates the water that flows into and away from a catchment. A basin integrates the disparate hydrologic activities occurring spatially within its domain. Streamflow characteristics are a manifestation of the combined results of various hydrologic processes occurring in a basin. Basin water balance investigation yields information on how much water is gained and lost in quantitative terms.
Ming-ko Woo

Backmatter

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