March 17, 2022 — Scientists study the topography—the forms and features of the landscape—to measure and observe changes at the Earth’s surface over time. While some changes are the result of natural processes like fluvial erosion and coastal erosion, the topography can also change due to anthropogenic forces, including those related to urban development, agriculture and resource extraction.

In a new study by the OpenTopography team, scientists examined topographic change over the entire state of Indiana across the span of almost a decade. The study evaluated landscape changes driven by infrastructure development, vegetation growth, agricultural practices, river and coastal processes, and natural resource extraction.

Led by Arizona State University (ASU) researcher Chelsea Scott, in collaboration with researchers from San Diego Supercomputer Center (SDSC) at UC San Diego and UNAVCO, the study included observations of physical changes to the Earth’s surface such as movement and removal of rock material in quarries, erosion and deposition by major rivers, significant erosion along the Lake Michigan shoreline near Indiana Dunes National Park, new housing developments and highways, and land use changes related to agricultural activities.

The study’s findings are published in a paper titled, Statewide USGS 3DEP Lidar Topographic Differencing Applied to Indiana, USA, in the journal Remote Sensing. The results are also available as an easy-to-explore web map that provides a full visualization of the statewide topographic change results.

Using high-resolution lidar (light detection and ranging) topography data collected over the state of Indiana between 2011–2013 and 2016–2020, the researchers calculated both the change of the bare earth surface (minus the vegetation and built structures) and the full surface (the bare surface plus above-ground features like vegetation, buildings, and other structures).

OpenTopography already provides web-based, on-demand tools for its users to compute landscape change for its hosted spatially overlapping lidar datasets. These tools include vertical and 3D differencing algorithms as described in a research article in the journal Geosphere. The compute intensive nature of these algorithms and massive volumes associated with lidar data restrict processing to limited spatial extents at a time. Given the large volumes of data that had to be processed for this Indiana project, the team leveraged dedicated high-performance computing (HPC) resources at SDSC for faster processing and more reasonable timelines for analysis.

“Easy access to HPC resources is essential in advancing Earth Science research,” said Viswanath Nandigam, principal investigator of OpenTopography. “The availability of HPC resources at SDSC like the Expanse supercomputer will play a critical part in solving Big Data cyberinfrastructure challenges of the future.”

“We calculated meter-scale topographic change at the largest spatial extent yet by using data collected by the U.S. Geological Survey’s 3D Elevation Program (3DEP). This program is likely to have national coverage in a couple of years,” said Scott, a co-investigator of OpenTopography. “We solved a number of Big Data geospatial challenges that we hope can be applied to this national-wide dataset to address future questions in hydrology, biomass change and hazards as well as the interaction between people and the planet’s landscape.”

As the USGS’s 3DEP activity aims to provide topographic lidar coverage of the entire lower 48 states by 2023, there is growing potential to perform additional work evaluating large-scale topographic change. These studies will be crucial in better characterizing Earth’s landscape and how it changes over time.

About OpenTopography

OpenTopography is a U.S. National Science Foundation-funded facility that works to facilitate community access to high-resolution, Earth science-oriented topography data and related tools and resources. The OpenTopography facility is based at SDSC at UC San Diego and is operated in collaboration with ASU and UNAVCO, a non-profit university-governed consortium. OpenTopography is supported by the National Science Foundation (award nos. 1948997, 1948994 and 1948857).

About SDSC

SDSC, located at UC San Diego, is considered a leader in data-intensive computing and cyberinfrastructure, providing resources, services and expertise to the national research community, including industry and academia. Cyberinfrastructure refers to an accessible, integrated network of computer-based resources and expertise, focused on accelerating scientific inquiry and discovery. SDSC supports hundreds of multidisciplinary programs spanning a wide variety of domains, from earth sciences and biology to astrophysics, bioinformatics and health IT.

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Source: Kimberly Mann Bruch, UCSD