Digital terrain modelling: A review of hydrological, geomorphological, and biological applications

Abstract

The topography of a catchment has a major impact on the hydrological, geomorphological. and biological processes active in the landscape. The spatial distribution of topographic attributes can often be used as an indirect measure of the spatial variability of these processes and allows them to be mapped using relatively simple techniques. Many geographic information systems are being developed that store topographic information as the primary data for analysing water resource and biological problems. Furthermore, topography can be used to develop more physically realistic structures for hydrologic and water quality models that directly account for the impact of topography on the hydrology. Digital elevation models are the primary data used in the analysis of catchment topography. We describe elevation data sources, digital elevation model structures, and the analysis of digital elevation data for hydrological, geomorphological, and biological applications. Some hydrologic models that make use of digital representations of topography are also considered. K E Y WORDS Basin topography Digital elevation models Terrain analysis Hydrologic models -6087/9and diversity within landscapes. A number of hydrologically-based, topographically-derived indices appear to be particularly powerful and useful for determining this susceptibility to hazard (Moore and Nieber, 1989). Many geographic information systems and resource inventory systems are being developed storing topographic information as primary data for use in analysing water resource and biological problems. This paper reviews the availability of digital elevation data and its accuracy, digital representation of topography, analysis of the digital data for hydrological, geomorphological, and biological applications, and describes some models that make use of digital representations of topography. We use examples from Australia and the United States of America in our discussions because of our familiarity with hydrologic research and practice in these two countries. DIGITAL ELEVATION MODELSA Digital Elevation Model (DEM) is an ordered array of numbers that represents the spatial distribution of elevations above some arbitrary datum in a landscape. I t may consist of elevations sampled at discrete points or the average elevation over a specified segment of the landscape, although in most cases it is the former. DEMs are a subset of Digital Terrain Models (DTMs) which can be defined as ordered arrays of numbers that represent the spatial distribution of terrain attributes.The acquisition. storage, and presentation of topographic information is an area of active research.Generally, raw elevation data in the form of stereo photographs or field surveys, and the equipment to process these data, are not readily available to potential end users of a DEM. Therefore, most users must rely on published topographic maps or DEMs produced by government agencies such as the United States Geological Survey (U.S.G.S.) or the Australian Surveying and Land Information Group (AUSLIG-formerl...

Soil-induced impacts on forest structure drive coarse woody debris stocks across central Amazonia

“…A topographic index (TI) that estimates drainage of each SRTM pixel (Moore et al 1991) was calculated using ArcMap:…”

A comparison of simplified methods for routing topographically driven subsurface flow

“…Recently, there has been an explosion of interest in distributed hydrologic models made possible by increased computational capabilities of low-cost desktop computers, and the availability of spatially distributed databases for soils, topography, and vegetation data in Geographic Information System formats [see, e.g., Moore et al, 1991]. Nonetheless, relatively little attention has been given to the representation of subsurface flow in the plethora of Topmodel-based applications.…”

Observed spatial organization of soil moisture and its relation to terrain indices

“…Most of the indices currently in use allow some interpretation of the physical rationale behind them. Terrain indices can be grouped into primary terrain attributes, such as slope, aspect, curvature, and specific catchment area, and compound attributes that are combinations of primary attributes [Moore et al, 1991]. Surface slope, tan(B), influences the hydraulic gradient driving any surface flows and also subsurface flows when the water table has a similar slope to the ground surface.…”

“…Local variations in potential evapotranspiration can be characterized by indices such as the potential solar radiation index that quantifying solar energy inputs to different topographic locations. The potential solar radiation index is the ratio of the potential solar radiation (i.e., the solar radiation in the absence of an atmosphere) on a sloping surface to that on a horizontal surface [Moore et al, 1991]. Spatial variations in humidity are unlikely to be significant at small (500 m) catchment scales owing to mixing in the atmospheric boundary layer.…”