Robert J. Peckham - Gyozo Jordan (Eds.)

Digital Terrain Modelling

Preface Contents The book has been published in the Springer series Lecture Notes in Geoinformation and Cartography: LECTURE NOTES IN GEOINFORMATION AND CARTOGRAPHY The Lecture Notes in Geoinformation and Cartography series provides a contemporary view of current research and development in Geoinformation and Cartography, including GIS and Geographic Information Science. Publications with associated electronic media examine areas of development and current technology. Editors from multiple continents, in association with national and international organizations and societies bring together the most comprehensive forum for Geoinformation and Cartography.

The scope of Lecture Notes in Geoinformation and Cartography spans the range of interdisciplinary topics in a variety of research and application fields. The type of material published traditionally includes:
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The Lecture Notes in Geoinformation and Cartography series also includes various other publications, including:
- tutorials or collections of lectures for advanced courses;
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- emerging areas of research directed at a broad community of practitioners.
More detailed information on the Lecture Notes in Geoinformation and Cartography can be found at http://www.springer.com. Proposals for publication should be sent to Christian.Witschel@springer.com.

Development and Applications in a Policy Support Environment

This volume presents a set of papers on Digital Terrain Modelling oriented towards applications for Policy Support. It is a compilation of research results by international groups, mostly based at the European Commission's Joint Research Centre, providing scientific support to the development and implementation of EU environmental policy. The first six papers describe recent advances in the theories and foundations as well as the practical techniques for developing and tailoring digital terrain models for their intended purposes, while the following papers focus on specific applications. Applications include the pan- European River and Catchment Database, European Flood Alert System, European Digital Soil Database and solar energy resource assessment, all discussed in a GIS framework in the context of the INfrastructure for SPatial InfoRmation in Europe (INSPIRE). This practice-oriented book is recommended to environmental modelers and GIS experts working on regional planning and policy support applications.

Preface

This book presents a set of papers on Digital Terrain Modelling for Policy Support which aims to be informative and stimulating for both developers and users of digital terrain models. It should also be useful for professionals who are interested in the wider aspects of the applications of terrain models in support for policies and decision making.

There is an increasing demand for regional and continental scale data for use in environmental modelling and spatial analysis to support environmental policy development and implementation. Important environmental processes act at regional and continental scales, for example climatic change inducing floods and soil erosion, and management of these processes for the sustainable development of society requires policies to be applied at the corresponding scales. One of the most important factors influencing these environmental processes which act on the earth's surface is the surface topography, hence the need for extensive, harmonised digital terrain models.

Despite the steadily increasing literature on the developing field of digital terrain modelling, there is a lack of information about their regional and policy applications. Some reasons for this are that, on one hand, policies are only recently being developed for the regional and continental scales, and are still largely limited to developed parts of the world and, on the other hand, large-scale DEMs and the required computational power have only become widely available relatively recently. This book therefore aims to give an inspiring insight into the problems, methods and some of the applications of DEMs in policy support. It is practice-oriented by providing descriptions of algorithms, databases and information sources oriented to the environmental modeller and GIS expert working on regional planning and policy support applications.

The first six papers describe recent advances in the theories and foundations as well as the practical techniques for developing and tailoring the digital terrain models for their intended purposes. The topics addressed include the mathematical and numerical development of digital terrain analysis for geomorphometric and surface transport modelling, the use of mathematical morphology and image analysis to describe terrain features, optimisation of interpolation parameters using cross-validation, and the influence of input data design on the accuracy of the resulting elevation models. Also reported are projects which are making use of data from the Shuttle Radar Topography Mission (SRTM). Modern techniques for data capture based on space technology now allow us to obtain elevation information on a European and even global scale, but even with these methods for extensive data capture a lot of work still needs to be done in processing, refining and adapting the data for its specific purpose. These techniques are brought out in papers describing development of European databases for use in soil applications and hydrology.

The following five papers focus more closely on applications. Three are devoted to applications of digital terrain models related to flooding, including a decision support system for flood control, flood risk mapping, and the design of flood emergency reservoirs. The next paper describes the development of physiographic units for the European sector of the World Soil and Terrain (SOTER) Digital Database, which has a very broad range of applications in the management of agricultural and environmental resources. The final application is solar energy resource modelling, for which elevation, aspect and slope are key input data.

Two further technical notes describe statistical tools for analysis of Digital Elevation Models, and the definition and calculation of the Potential Drainage Density Index which is useful for characterising landscapes in hydrogeological applications.

We are especially grateful to the European Commission's Joint Research Centre (JRC) which has contributed extensively to this volume. Most of the authors of the presented papers are either based at the JRC's Environment Institute, or have spent some time there working on digital terrain models in a policy support context. The JRC is concerned with the application of the innovations in science and technology to support policies for the whole of Europe and it is therefore particularly appropriate that they are involved in the development of the methods and applications for Digital Terrain Modelling over this extensive region. In order to provide sound, fair and well balanced policy support for all European countries it is essential that the underlying scientific and technical data be accurate, reliable, and harmonised for their intended purpose. The work on harmonising geospatial information in general is of special concern for the European Commission, as it is needed to sustain many European Policy areas, and the JRC is strongly supporting the INSPIRE initiative (Infrastructure for Spatial Information in Europe) which is working towards this goal. Digital Terrain Models are an excellent example of a type of geographic information where, in the past, different approaches, methods and standards applied in different countries have lead to discrepancies arising at country borders when information is put together. These discrepancies can no longer be tolerated when we need to model and simulate, for example, flooding in rivers which cross the borders. The work described in this book can therefore be seen as a contribution to the INSPIRE initiative, but also an essential step in making Digital Terrain Models applicable for a range of policy applications over a wide region. The scientific and technical foundations of this, including the theories, methods, and algorithms, are the daily work of the authors of these papers and we sincerely thank them all for their substantial contributions and patience during the editing phase. Additional thanks are due to Pierre Soille for his excellent assistance with indexing.

We hope that this book will provide a useful input to the research field of Digital Terrain Modelling, as well as a helpful support, and indeed an inspiration to people working in this area.

Robert Peckham
Gyozo Jordan
January 2007

CHAPTER 1.
DIGITAL TERRAIN ANALYSIS IN A GIS ENVIRONMENT
CONCEPTS AND DEVELOPMENT	1
Gyozo Jordan

1. Introduction	1
2. Digital Terrain Analysis in a GIS Environment	2
3. Mathematical Development	4
3.1 Vector-scalar Functions: Spatial Curves, Curvature and Surfaces	4
3.2 Scalar-vector Functions: Gradient Vector, Slope and Aspect	14
3.3 The Link between Surface Geometry and Surface Flow: Gradient and Curvature	17
3.4 Vector Analysis and Digital Terrain Modelling: Geometric Characterisation of Topographic Surfaces	20
4. Numerical Methods	21
4.1 Digital Representation of Topographic Surface: Continuity and Smoothness	21
4.2 Calculation of Partial Derivatives for Gradient and Curvature Estimation	24
4.3 Which Gradient Calculation Method Should be Used?	28
4.4 Avoiding Second-order Derivatives: Break Lines and Inflexion Lines	33
4.5 Calculation of Singular Points	35
4.6 Digital Drainage Analysis: Ridge and Valley Lines	37
5. Conclusions	38
References	39

CHAPTER 2.
FROM MATHEMATICAL MORPHOLOGY TO MORPHOLOGICAL TERRAIN FEATURES	45
Pierre Soille
1. Introduction	45
2. First Steps in Mathematical Morphology	46
2.1 Erosion and Dilatation	46
2.2 Opening and Closing.	47
2.3 Geodesic Transformations	47
3. From Topographic Maps to DEMs	50
3.1 Plateau Image Generation	51
3.2 Interpolation Along Steepest Slope Lines	51
4. From DEMs to River Networks	52
4.1 Spurious Pits and their Suppression	54
4.2 Flow Directions	57
4.3 Contributing Drainage Areas	59
5. Dividing Lines	59
5.1 Watersheds	62
5.2 Crest Lines	62
6. Concluding Remarks	62
References	63

CHAPTER 3.
OPTIMISATION OF INTERPOLATION PARAMETERS USING CROSS-VALIDATION	67
Jaroslav Hofierka, Tomás Cebecauer and Marcel Súri
1. Introduction	67
2. Interpolation by Regularised Spline with Tension	68
3. The RST Control Parameters	70
4. Evaluation of Interpolation Accuracy	71
5. Application to Digital Terrain Modelling	73
6. Results and Discussion	75
7. Conclusions	79
References	81

CHAPTER 4.
SCALE-DEPENDENT EFFECT OF INPUT DATA DESIGN ON DEM ACCURACY	83
Radoslav Bonk
1. Introduction	83
2. Study Area	86
3. Methodology	87
3.1 Statistical Analysis of Interpolated Surfaces	88
4. Results	89
4.1 Statistical Analysis	89
4.2 Spatial Autocorrelation	91
5. Discussion	92
6. Conclusions	93
References	97
Referenced Web Sites	98

CHAPTER 5.
SRTM AS A POSSIBLE SOURCE OF ELEVATION INFORMATION FOR SOIL-LANDSCAPE MODELLING	99
Borut Vrscaj, Joël Daroussin and Luca Montanarella
1. Introduction	99
2. Gaps and Noise in SRTM Data	100
3. Digital Surface Model vs. Digital Elevation Model	101
4. Materials and Methods	103
4.1 Description of the Test Area	103
4.2 SRTM Elevation Data	104
5. Results and Discussion	107
5.1 Possible Solutions for Data Improvement of SRTM	107
6. Case Study	111
6.1 Quantitative Comparison of the SRTM DEM to National DEMs	111
7. Two Possible SRTM Processing Workflows	115
7.1 Workflow for Building a Seamless Pan-European DEM for Noncritical Applications	115
7.2 Procedure for Building a Seamless DEM	116
8. Conclusions	116
References	118
Referenced Web Sites	119
Appendix	119
1. Commands	119
2. Software applications	120
3. Selected data sources	120

CHAPTER 6.
DEVELOPMENT OF A PAN-EUROPEAN RIVER AND CATCHMENT DATABASE	121
Jürgen Vogt, Pierre Soille, Roberto Colombo, Maria Luisa Paracchini and Alfred de Jager
1. Introduction	121
2. Study Area	123
3. Input Data	124
3.1 Digital Elevation Data	124
3.2 Inland Water Body Layer	125
3.3 Environmental Data Layers	126
4. Methodology	127
4.1 Landscape Stratification	128
4.2 Threshold Definition	130
4.3 River Network Extraction	133
4.4 Drainage Basin Delineation	135
5. Data Validation	135
6. Additional Features	137
6.1 Pfafstetter Coding	137
6.2 Adding Names to Rivers and Catchments	139
7. Conclusions and Outlook	140
References	141
Referenced Web Sites	144

CHAPTER 7.
DECISION SUPPORTING HYDROLOGICAL MODEL FOR RIVER BASIN FLOOD CONTROL	145
János Adolf Szabó
1. Introduction	145
2. The DIWA Model	147
2.1 Cell Link Network Definition Based on Digital Elevation Model (DEM)	149
2.2 Rain or Snow, and Snowmelt	151
2.3 Interception and Through-fall Estimation	151
2.4 Evaporation and Evapotranspiration	152
2.5 Modelling of the Subsurface Run-off Processes	154
2.6 Surface Run-off Calculation	160
2.7 Numeric Solution	161
2.8 Some Numerical Aspects	162
3. Application of the DIWA Model in the Upper Part of the Tisza River Basin	163
3.1 Background and Some Characteristics of the Tisza Basin	163
3.2 Data Preparation and Pre-processing	168
3.3 Calibration and Validation	171
3.4 Scenario Analysis for Vegetation Density Changes on the Upper-Tisza Basin	176
4. Conclusions	178
References	180

CHAPTER 8.
POTENTIAL FLOOD HAZARD AND RISK MAPPING AT PANEUROPEAN SCALE	183
Ad De Roo, Jose Barredo, Carlo Lavalle, Katalin Bodis and Rado Bonk
1. Introduction	183
2. Flood Hazard Mapping Using DEM	185
3. Methodology	186
3.1 Step 1: Defining the Elevation Difference of Each Pixel with the River	187
3.2 Step 2: Defining the Critical Water Levels	187
4. Potential Flood Hazard Maps of Europe	191
5. Validation of the Flood Hazard Map	194
6. From Regional Flood Hazard to Regional Flood Risk	196
7. A Flood Risk Map of Europe	199
8. Conclusions	200
References	200
Referenced Web Sites	201

CHAPTER 9.
HIGH-RESOLUTION DEM FOR DESIGN OF FLOOD EMERGENCY RESERVOIRS	203
Katalin Bódis
1. Introduction	203
2. Materials and Methods	208
3. The Digital Elevation Model of the Reservoir	213
3.1 Source of DEM	213
3.2 Creation of DTM	213
3.3 Value Check of DTM	215
4. Application of DEM to Flood Mitigation Plans	217
4.1 Quick Area and Reservoir Capacity Calculation	217
4.2 Capacity Curve for Planning	219
4.3 Flow Direction, Inundation and Discharge Simulation, Running-off Modelling	219
4.4 Monitoring of Environmental Changes, Siltation	222
5. Conclusion	222
References	224
Referenced Web Sites	226

CHAPTER 10.
A QUANTITATIVE PROCEDURE FOR BUILDING PHYSIOGRAPHIC UNITS FOR THE EUROPEAN SOTER DATABASE	227
Endre Dobos, Joël Daroussin, Luca Montanarella
1. Introduction	227
2. Materials and Methods	230
2.1 The Study Area	230
2.2 The Data	230
2.3 Methods	232
3. Results and Discussion	246
4. Conclusions	254
References	255
Referenced Web Sites	256
Appendix	257

CHAPTER 11.
SOLAR RESOURCE MODELLING FOR ENERGY APPLICATIONS	259

Marcel Súri, Thomas Huld, Ewan D. Dunlop and Jaroslav Hofierka
1. Introduction	259
2. Solar Radiation Modelling	260
3. Spatially Distributed Solar Databases	261
4. Solar Radiation Model r.sun and Terrain Parameters	263
4.1 Elevation Above Sea Level	264
4.2 Inclination and Aspect	264
4.3 Shadowing	265
5. PVGIS: Application of solar Radiation Model in an Assessment of Photovoltaic Power generation	267
6. Conclusions	269
References	270
Referenced Web Sites	272

TECHNICAL NOTES

CHAPTER 12.
GRASS AND R - ADVANCED GIS AND STATISTICAL TOOLS FOR DEM ANALYSIS	275
Radoslav Bonk
1. Introduction	275
2. Case Study	276
3. Conclusions	281
References	282
Referenced Web Sites	282

CHAPTER 13.
CALCULATION OF POTENTIAL DRAINAGE DENSITY INDEX (PDD)	283
	283
Endre Dobos
1. Introduction	283
2. Derivation of the PDD Layer	285
2.1 Input DEM	285
2.2 Step 1. Flow Direction	286
2.3 Step 2. Flow Accumulation/Contributing Area/Catchment Area	286
2.4 Step 3. Drainage Network	286
2.5 Step 4. Potential Drainage Density (PDD)	288
References	290
Appendix: An Arc/Info® AML file to derive a PDD layer from a filled	290
DEM	290
ABOUT THE AUTHORS	297
INDEX	307