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.

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

https://www.clw.csiro.au/aclep/documents/McBratney%20et%20al.%202003.pdf

On digital soil mapping

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Landslide inventory maps: New tools for an old problem

A drainage basin simulation model introduced here incorporates creep and threshold slumping and both detachment- and transport-limited fluvial processes. Fluvial erosion of natural slopes and headwater channels is argued to be dominantly detachment-limited. Such slopes undergo nearly parallel retreat and replacement with alluvial surfaces under fixed base level, in contrast with gradual slope decline for transport-limited conditions. The arrangement of divides and valleys is sensitive to initial conditions, although average morphology is insensitive. Dissected, initially flat surfaces in which downstream concavity is slight exhibit nearly parallel drainage, compared to very wandering main valleys when concavity is great. Steady state is reached after a cumulative base level drop approximately 3 times the final relief. Simulated valley systems are similar to those predicted by a previous model of optimal drainage basins. A critical value of slope divergence normalized by average slope gradient is a useful criterion for defining the valley network.

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A detachment-limited model of drainage basin evolution

Predictive vegetation mapping can be defined as predicting the geographic distribution of the vegetation composition across a landscape from mapped environmental variables. Comput erized predictive vegetation mapping is made possible by the availability of digital maps of topography and other environmental variables such as soils, geology and climate variables, and geographic information system software for manipulating these data. Especially important to predictive vegetation mapping are interpolated climatic variables related to physiological tolerances, and topographic variables, derived from digital elevation grids, related to site energy and moisture balance. Predictive vegetation mapping is founded in ecological niche theory and gradient analysis, and driven by the need to map vegetation patterns over large areas for resource conservation planning, and to predict the effects of environmental change on vegetation distributions. Predictive vegetation mapping has advanced over the past two decades espe...

Predictive vegetation mapping: geographic modelling of biospatial patterns in relation to environmental gradients:

Land surface topography significantly affects the processes of runoff and erosion. A system which determines slope, aspect, and curvature in both the down-slope and across-slope directions is developed for an altitude matrix. Also, the upslope drainage area and maximum drainage distance are determined for every point within the altitude matrix. A FORTRAN 66 program performs the analysis.

Quantitative analysis of land surface topography

This report presents the findings of research to develop a practical methodology for predicting the rate and extent of channel migration in proximity to transportation facilities The report presents, in the form of a handbook, an empirical methodology developed for predicting stream meander migration The methodology presented in the handbook will assist practicing engineers in evaluating bridges and other structures and in determining the need for countermeasures to address the potential impacts of channel meander migration over the life of the facility This report will be particularly useful to structural, hydraulic, and highway engineers responsible for the design and construction of bridges or other structures in proximity to naturally meandering stream channels

Handbook for predicting stream meander migration

This report documents and presents the results of a study to develop a practical methodology to predict the rate and extent of channel migration in proximity to transportation facilities. The principal product of this research was a stand-alone Handbook for predicting stream meander migration using aerial photographs and maps. The Handbook is published separately as NCHRP Report 533. It deals specifically with the problem of incremental channel shift and provides a methodology for predicting the rate and extent of lateral channel shifting and down valley migration of meanders. The comparison technique developed for this project consists of overlaying channel banklines traced from successive historic maps or photos. Movement of bankline position is then evaluated by measuring the change in radius and movement of the centroid of best-fit circles on the banklines to provide a quantitative estimate of migration distance, rate, and direction over time. Predictions can then be made on the potential position of the river at some point in the future. The process can be completed manually or by using computer photo editing software. In addition, a GIS-based approach was developed with ArcView extensions to streamline the measurement and analysis of bend migration data and aid in predicting channel migration. The ArcView extensions are included in CRP-CD-48, which comes with NCHRP Report 533. The report also contains an archive of the data base compiled on CRP-CD-49 to include all meander site data acquired for this study (141 meander sites containing 1,503 meander bends on 89 rivers in the U.S.). The methodology developed will enable practicing engineers to evaluate and determine bridge and other highway facility locations and sizes and ascertain the need for countermeasures considering the potential impacts of channel meander migration over the life of a bridge or highway river crossing.

Methodology for predicting channel migration

This document provides guidelines for identifying stream instability problems at highway stream crossings. It is an update of the third edition published in 2001. The HEC-20 manual covers geomorphic and hydraulic factors that affect stream stability and provides a step-by-step analysis procedure for evaluation of stream stability problems. Stream channel classification, stream reconnaissance techniques, and rapid assessment methods for channel stability are covered in detail. Quantitative techniques for channel stability analysis, including degradation analysis, are provided, and channel restoration concepts are introduced. Significant new material in this edition includes chapters on sediment transport concepts and channel stability in gravel bed streams, as well as expanded coverage of channel restoration concepts.

Stream Stability at Highway Structures, Fourth Edition

Stream channel migration can have a significant impact on the design, maintenance, and inspection of bridges and other highway facilities. Practicing highway hydraulic engineers could benefit from a practical methodology to predict the rate and extent of channel migration in their efforts to reduce the cost of design, repair, rehabilitation, and countermeasures for lateral channel instability. The objective of Research Project 24-16 is to develop a practical methodology to predict the rate and extent of channel migration (i.e., lateral channel shift and down valley migration) near transportation facilities. The research approach for this project emphasizes enhancing and using empirical databases to develop predictive multiple regression or other statistical relationships, which include descriptors of, or surrogates for, bankline erodibility and floodplain characteristics. This will be accomplished through a series of tasks including: 1) a detailed literature review; 2) compilation and analysis of an extensive data set containing time-sequential aerial photography, stream gage data, and field measurement data from a variety of sources; 3) development of a screening procedure to identify stable meandering reaches; 4) development of a classification system for river/meander types to support stratification of the database; 5) development of guidelines for map/aerial photograph comparison techniques for predicting meander migration; 6) development of multiple regression relationships for predicting direction, location, and rate of meander migration; and 7) internal and external testing and evaluation of the methodology. The research products will include not only a final report describing the predictive methodology, but also an extensive archived database, published on CD-ROM, that contains detailed morphological data, aerial photos, historical banklines, and maps for more than 1,400 bends on 87 rivers and streams across the United States. In addition, a stand-alone aerial photo/map comparison handbook that provides a complete applications supplement for Project 24-16 will be published. The comparison techniques in the handbook will include GIS measurements and extrapolation routines. The archived database and handbook will be intended for use by FHWA and State DOTs, but should also be of interest to future researchers and practitioners responsible for river channel maintenance and river restoration/rehabilitation projects.

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Lyle W. Zevenbergen

Papers

Quantitative analysis of land surface topography

Handbook for predicting stream meander migration

Methodology for predicting channel migration

Stream Stability at Highway Structures, Fourth Edition

Methodology for Predicting Channel Migration: NCHRP Project No. 24-16