Helena Mitasova

Multivariate Interpolation of Precipitation Using Regularized Spline with Tension

Regularized Spline with Tension (RST) is an accurate, flexible and efficient method for multivariate interpolation of scattered data. This study evaluates its capabilities to interpolate daily and annual mean precipitation in regions with complex terrain. Tension, smoothing and anisotropy parameters are optimized using the cross-validation technique. In addition, smoothing and rescaling of the third variable (elevation) is used to minimize the predictive error. The approach is applied to data sets from Switzerland and Slovakia and interpolation accuracy is compared to the results obtained by several other methods, expert-drawn maps and measured runoff. The results demonstrate that RST performs as well or better than the methods tested in the literature. The incorporation of terrain improves the spatial model of precipitation in terms of its predictive error, spatial pattern and water balance.

Computational modeling and neolithic socioecological dynamics: A case study from Southwest Asia

Archaeology has an opportunity to offer major contributions to our understanding of the long-term interactions of humans and the environment. To do so, we must elucidate dynamic socioecological processes that generally operate at regional scales. However, the archaeological record is sparse, discontinuous, and static. Recent advances in computational modeling provide the potential for creating experimental laboratories where dynamic processes can be simulated and their results compared against the archaeological record. Coupling computational modeling with the empirical record in this way can increase the rigor of our explanations while making more transparent the concepts on which they are based. We offer an example of such an experimental laboratory to study the long-term effects of varying landuse practices by subsistence farmers on landscapes, and compare the results with the Levantine Neolithic archaeological record. Different combinations of intensive and shifting cultivation, ovicaprid grazing, and settlement size are modeled for the Wadi Ziqlab drainage of northern Jordan. The results offer insight into conditions under which previously successful (and sustainable) landuse practices can pass an imperceptible threshold and lead to undesirable landscape consequences. This may also help explain long-term social, economic, and settlement changes in the Neolithic of Southwest Asia.

Raster-Based Analysis of Coastal Terrain Dynamics from Multitemporal Lidar Data

Abstract Multitemporal sets of lidar data provide a unique opportunity to analyze and quantify changes in topography in rapidly evolving landscapes. Methodology for geospatial analyses of lidar data time series was developed to investigate patterns of coastal terrain evolution, including the beach and dune systems. The diverse lidar-point data density, noise, and systematic errors were first quantified, and the results were used to compute a consistent series of high-resolution digital elevation models using spline-based approximation with optimized parameters. Raster-based statistical analysis was applied to the elevation-model time series to derive maps representing multiyear trends in spatial patterns of elevation change, to quantify dynamics at each cell using standard deviation maps, and to extract the core surface below which the elevation has never decreased. The methodology was applied to a North Carolina barrier island that was mapped by a sequence of 13 lidar surveys during the past decade, using several different lidar systems. Assessment of vertical differences between the lidar data sets using stable structures such as a road, was shown to be essential for correct quantification of coastal terrain change and its pattern. The analysis revealed the highly dynamic nature of foredunes, the trend toward inland sand transport, and the impact of anthropogenic sand disposal on that trend.

Quantifying Rapid Changes in Coastal Topography using Modern Mapping Techniques and Geographic Information System

Innovative methodology based on a combination of real-time kinematic Global Positioning System (RTK-GPS), light detection and ranging (lidar), and open-source Geographic Information System (GIS) was developed to gain a better understanding of rapid changes in coastal topography. Improved spatial interpolation techniques were implemented to produce detailed topographic surfaces from lidar and RTK-GPS data. The methodology is demonstrated for two North Carolina areas: Jockeys Ridge State Park and Bald Head Island. The Jockeys Ridge study quantifies recent dune movement and identifies areas of elevation loss and rapid horizontal migration that threaten existing infrastructure. The Bald Head Island study examines pre- and post-nourishment beach evolution. The dynamics of beach topography, its geometric properties, and estimates of both eroded and deposited sand volumes were determined by combining lidar elevation data (1997–2000) with quarterly RTK-GPS measurements. Spatio-temporal analysis confirms the relative stability of the central ‘pivot point’ beach section and reveals that the beach changed its shape from convex west of the pivot point to concave east of the pivot point during the period of 1997 to 1998 and reversed shapes during year 2000. The pivot point also divides the beach into two sections that exhibit markedly different responses to nourishment. Although the entire length of nourished beach retreated, the analysis reveals that in the western section, all nourished sand off-shore was lost, whereas in the eastern section, significant sand volume was pushed up onto the beach, creating potential for recovery.

TanGeoMS: Tangible Geospatial Modeling System

We present TanGeoMS, a tangible geospatial modeling visualization system that couples a laser scanner, projector, and a flexible physical three-dimensional model with a standard geospatial information system (GIS) to create a tangible user interface for terrain data. TanGeoMS projects an image of real-world data onto a physical terrain model. Users can alter the topography of the model by modifying the clay surface or placing additional objects on the surface. The modified model is captured by an overhead laser scanner then imported into a GIS for analysis and simulation of real-world processes. The results are projected back onto the surface of the model providing feedback on the impact of the modifications on terrain parameters and simulated processes. Interaction with a physical model is highly intuitive, allowing users to base initial design decisions on geospatial data, test the impact of these decisions in GIS simulations, and use the feedback to improve their design. We demonstrate the system on three applications: investigating runoff management within a watershed, assessing the impact of storm surge on barrier islands, and exploring landscape rehabilitation in military training areas.

Path sampling method for modeling overland water flow, sediment transport, and short term terrain evolution in Open Source GIS

A path sampling method is proposed for solving the continuity equations describing mass flows over complex landscape surfaces. The modeled quantities are represented by an ensemble of sampling points which are evolved according to the corresponding Green function. The method enables incorporation of multi-scale/multi-process treatments. It has been used to develop simulation tools for overland shallow water flow and for sediment transport. The spatial pattern of sediment flow and net erosion/deposition is modeled using the closure relationship between sediment transport capacity and detachment developed for the USDA Water Erosion Prediction Project. The tools were recently implemented as modules in Open Source GRASS GIS. Their application is illustrated by the study of impact of land use and topography change on overland flow and sediment transport at North Carolina State University campus.

Real-time landscape model interaction using a tangible geospatial modeling environment

Emerging technologies that combine the flexibility of digital landscape representation with easy-to-interpret 3D physical models open new possibilities for user interaction with geospatial data. A prototype tangible geospatial modeling environment lets users interact with landscape analysis and simulations using a tangible physical model. We introduce a concept that builds upon previous independent tangible user interface (TUI) and terrain analysis research and aims at more intuitive collaborative interaction with digital landscape data

GRASS as Open Source Free Software GIS: Accomplishments and Perspectives

Over the past decade Geographic Information Systems (GIS) have entered many new disciplines and have become part of general computational infrastructure. Therefore it is not surprising that geoinformation technology is also being developed within the Open Source and Free Software community, well known for its GNU/Linux system. The concept of “Free Software” was first defined by Richard M. Stallman in the form of four freedoms:

Tangible Modeling with Open Source GIS

This book presents a new type of modeling environment where users interact with geospatial simulations using 3D physical models of studied landscapes. Multiple users can alter the physical model by hand during scanning, thereby providing input for simulation of geophysical processes in this setting. The authors have developed innovative techniques and software that couple this hardware with open source GRASS GIS, making the system instantly applicable to a wide range of modeling and design problems. Since no other literature on this topic is available, this Book fills a gap for this new technology that continues to grow. Tangible Modeling with Open Source GIS will appeal to advanced-level students studying geospatial science, computer science and earth science such as landscape architecture and natural resources. It will also benefit researchers and professionals working in geospatial modeling applications, computer graphics, hazard risk management, hydrology, solar energy, coastal and fluvial flooding, fire spread, landscape, park design and computer games.

Modeling and analysis of landscape evolution using airborne, terrestrial, and laboratory laser scanning

Current laser scanning (Lidar, light detection and ranging) technologies span a wide range of survey extent and resolutions, from regional airborne Lidar mapping and terrestrial Lidar field surveys to laboratory systems utilizing indoor three-dimensional (3D) laser scanners. Proliferation in Lidar technology and data collection enables new approaches for monitoring and analysis of landscape evolution. For example, repeat Lidar surveys that generate a time series of point cloud data provide an opportunity to transition from traditional, static representations of topography to terrain abstraction as a 3D dynamic layer. Three case studies are presented to illustrate novel techniques for landscape evolution analysis based on time series of Lidar data: (1) application of multiyear airborne Lidar surveys to a study of a dynamic coastal region, where the change is driven by eolian sediment transport, wave-induced beach erosion, and human intervention; (2) monitoring of vegetation growth and the impact of landscape structure on overland flow in an agricultural field using terrestrial laser scanning; and (3) investigation of landscape design impacts on overland water flow and other physical processes using a tangible geospatial modeling system. The presented studies demonstrate new insights into landscape evolution in different environments that can be gained from Lidar scanning spanning 1.0–0.001 m resolutions with geographic information system analysis capabilities.