Jennifer Jensen

Texas State University

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David R. Butler

Texas State University

Russell Weaver

Cornell University

Lee A. Vierling

University of Idaho

Chunhong Zhao

Northeast Normal University

Anshuman Bhardwaj

University of Aberdeen

Adam J. Mathews

Binghamton University

Brittany C. Courville

Texas State University

T. Edwin Chow

Texas State University

Mark A. Fonstad

University of Oregon

Saeideh Gharehchahi

Jacksonville State University

Cooperative Institutions

Turku Centre for Computer Science

University of Turku

Texas State University

St Petersburg University

Astronomical Observatory

Institute of Applied Astronomy

Southampton City Council

University of Idaho

Abastumani Astrophysical Observatory

National Institute for Astrophysics

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A study of the relationship between fire hazard and burn severity in Grand Teton National Park, USA

International Journal of Applied Earth Observation and Geoinformation (2021)

David M. Szpakowski Jennifer Jensen David R. Butler T. Edwin Chow

Fire hazard maps are a useful tool which help land managers with wildfire mitigation planning. These maps are used for predicting the likelihood of fire ignition, fire behavior and effects, and can be generated using different techniques. However, the relationship between fire hazard and the resulting burn severity has not been fully explored. This paper presents a new method for assessing fire hazard and examines the relationship between fire hazard and burn severity. The 2016 Berry Fire in Grand Teton National Park is used as a case study for this examination. Fire hazard was calculated using a multicriteria evaluation based on fuel type, canopy cover, moisture conditions, topography, and infrastructure. Additionally, several previously proposed fire hazard indices were generated for comparison. All fire hazard indices were compared to the burn severities for the Berry Fire to determine if a relationship existed between fire hazard and burn severity. The proposed model exhibited a moderate relationship with two of the tested burn severity categories (unburned and moderate to high) and a weak relationship with the other categories (low, moderate, high). The other fire hazard indices exhibited very weak relationships with burn severity and in some instances the relationship was the inverse of what was expected.

Fire hazard

10.1016/j.jag.2021.102305

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Citations (7)

An airborne LiDAR-based methodology for vineyard parcel detection and delineation

International Journal of Remote Sensing (2012)

Adam J. Mathews Jennifer Jensen

An airborne lidar-based technique to delineate vineyard parcels from surrounding land uses is proposed and assessed in the Texas Hill Country American Viticultural Area near Austin, Texas, USA. Although most vineyard site analyses are based on multispectral aerial and satellite images, this study takes advantage of the height-based uniqueness of vineyard land uses inherent in the vine-trellising structure to differentiate vineyard areas from non-vineyard areas. A normalized digital surface model was created from lidar data and smoothed with a focal statistics method to identify vine rows and delineate vineyard land-use parcels. A simple unsupervised classification of the three study sites was performed to identify low vegetation areas. The vineyard areas were extracted from the low vegetation class and compared with manually digitized versions. The results suggest that lidar-based data sets can efficiently differentiate vineyard from non-vineyard land use. Our study yielded a mean classification accuracy of 97.55% and successfully extracted vineyard parcel area (mean accuracy 88.79%).

Vineyard

Land Cover

Vine

10.1080/01431161.2012.663114

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Citations (20)

Assessment of Image-Based Point Cloud Products to Generate a Bare Earth Surface and Estimate Canopy Heights in a Woodland Ecosystem

Remote Sensing (2016)

Jennifer Jensen Adam J. Mathews

We examine the utility of Structure from Motion (SfM) point cloud products to generate a digital terrain model (DTM) and estimate canopy heights in a woodland ecosystem in the Texas Hill Country, USA. Very high spatial resolution images were acquired with a Canon PowerShot A800 digital camera mounted on an unmanned aerial system. Image mosaicking and dense point matching were accomplished using Agisoft PhotoScan. The resulting point cloud was classified according to ground/non-ground classes and used to interpolate a high resolution DTM which was both compared to a DTM from an existing lidar dataset and used to model vegetation height for fifteen 20 × 20 m plots. Differences in the interpolated DTM surfaces demonstrate that the SfM surface overestimates lidar-modeled ground height with a mean difference of 0.19 m and standard deviation of 0.66 m. Height estimates obtained solely from SfM products were successful with R2 values of 0.91, 0.90, and 0.89 for mean, median, and maximum canopy height, respectively. Use of the lidar DTM in the analyses resulted in R2 values of 0.90, 0.89, and 0.89 for mean, median, and maximum canopy height. Our results suggest that SfM-derived point cloud products function as well as lidar data for estimating vegetation canopy height for our specific study area.

Digital surface

Structure from Motion

Elevation (ballistics)

10.3390/rs8010050

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Citations (140)

Local- and Regional-Scale Forcing of Glacier Mass Balance Changes in the Swiss Alps

Remote Sensing (2021)

Saeideh Gharehchahi Thomas J. Ballinger Jennifer Jensen Anshuman Bhardwaj Lydia Sam

Glacier mass variations are climate indicators. Therefore, it is essential to examine both winter and summer mass balance variability over a long period of time to address climate-related ice mass fluctuations. In this study, we analyze glacier mass balance components and hypsometric characteristics with respect to their interactions with local meteorological variables and remote large-scale atmospheric and oceanic patterns. The results show that all selected glaciers have lost their equilibrium condition in recent decades, with persistent negative annual mass balance trends and decreasing accumulation area ratios (AARs), accompanied by increasing air temperatures of ≥ +0.45 °C decade−1. The controlling factor of annual mass balance is mainly attributed to summer mass losses, which are correlated with (warming) June to September air temperatures. In addition, the interannual variability of summer and winter mass balances is primarily associated to the Atlantic Multidecadal Oscillation (AMO), Greenland Blocking Index (GBI), and East Atlantic (EA) teleconnections. Although climate parameters are playing a significant role in determining the glacier mass balance in the region, the observed correlations and mass balance trends are in agreement with the hypsometric distribution and morphology of the glaciers. The analysis of decadal frontal retreat using Landsat images from 1984 to 2014 also supports the findings of this research, highlighting the impact of lake formation at terminus areas on rapid glacier retreat and mass loss in the Swiss Alps.

Glacier mass balance

Forcing (mathematics)

10.3390/rs13101949

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Citations (7)

Topographic structure from motion: a new development in photogrammetric measurement

Earth Surface Processes and Landforms (2012)

Mark A. Fonstad J. Dietrich Brittany C. Courville Jennifer Jensen Patrice Carbonneau

ABSTRACT The production of topographic datasets is of increasing interest and application throughout the geomorphic sciences, and river science is no exception. Consequently, a wide range of topographic measurement methods have evolved. Despite the range of available methods, the production of high resolution, high quality digital elevation models (DEMs) requires a significant investment in personnel time, hardware and/or software. However, image‐based methods such as digital photogrammetry have been decreasing in costs. Developed for the purpose of rapid, inexpensive and easy three‐dimensional surveys of buildings or small objects, the ‘structure from motion’ photogrammetric approach (SfM) is an image‐based method which could deliver a methodological leap if transferred to geomorphic applications, requires little training and is extremely inexpensive. Using an online SfM program, we created high‐resolution digital elevation models of a river environment from ordinary photographs produced from a workflow that takes advantage of free and open source software. This process reconstructs real world scenes from SfM algorithms based on the derived positions of the photographs in three‐dimensional space. The basic product of the SfM process is a point cloud of identifiable features present in the input photographs. This point cloud can be georeferenced from a small number of ground control points collected in the field or from measurements of camera positions at the time of image acquisition. The georeferenced point cloud can then be used to create a variety of digital elevation products. We examine the applicability of SfM in the Pedernales River in Texas (USA), where several hundred images taken from a hand‐held helikite are used to produce DEMs of the fluvial topographic environment. This test shows that SfM and low‐altitude platforms can produce point clouds with point densities comparable with airborne LiDAR, with horizontal and vertical precision in the centimeter range, and with very low capital and labor costs and low expertise levels. Copyright © 2012 John Wiley & Sons, Ltd.

Structure from Motion

Orthophoto

Elevation (ballistics)

Georeference

Digitization

Total station

10.1002/esp.3366

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Citations (1,069)

The influence of environmental variables on intra-seasonal radial stem growth dynamics at the Arctic forest-tundra ecotone using point dendrometers

AGU Fall Meeting Abstracts (2020)

Jennifer Jensen Kevin L. Griffin Jan U.H. Eitel Natalie T. Boelman Lee A. Vierling

Ecotone

Source

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Citations (0)

Correction: Gharehchahi, S.; James, W.H.M.; Bhardwaj, A.; Jensen, J.L.R.; Sam, L.; Ballinger, T.J.; Butler, D.R. Glacier Ice Thickness Estimation and Future Lake Formation in Swiss Southwestern Alps—The Upper Rhône Catchment: A VOLTA Application. Remote Sens. 2020, 12, 3443

Remote Sensing (2020)

Saeideh Gharehchahi William James Anshuman Bhardwaj Jennifer Jensen Lydia Sam

The authors wish to make the following corrections to this paper [...]

10.3390/rs12223709

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Citations (2)

Data synergy between leaf area index and clumping index Earth Observation products using photon recollision probability theory

Remote Sensing of Environment (2018)

Jan Písek Henning Buddenbaum Fernando Camacho Joachim Hill Jennifer Jensen

Earth observation

Imaging spectrometer

10.1016/j.rse.2018.05.026

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Citations (11)

Applying Floodplain Inundation Modeling to Estimate Suitable Spawning Habitat and Recruitment Success for Alligator Gar in the Guadalupe River, Texas

Hydrology (2023)

Kimberly M. Meitzen Clinton R. Robertson Jennifer Jensen Daniel J. Daugherty Thomas B. Hardy

We developed a floodplain inundation model to extract specific flood extent and depth parameters and combined these with vegetation land cover and historic flow data to quantify spatial habitat suitability and temporal hydrologic metrics that support Alligator Gar Atractosteus spatula spawning within a 257 km segment of the lower Guadalupe River, Texas, USA. We modeled nine flows across a range of flood frequency recurrence intervals from 257 m3s−1 to ~4997 m3s−1 and estimated the availability of suitable spawning water depths (0.2 to 2 m) and lateral connectedness between the river and suitable floodplain landcover types. We estimated the ages via otoliths of 95 Alligator Gar collected in the reach to determine the year that they were recruited into the system. We analyzed a total of 30 Indicators of Hydrologic Alteration flow metrics to examine how the spatially derived suitable habitats related to the temporal aspects of flow occurrence during the spawning season for the period of flow record April–July (1935–2020) and to the years spanning the recruitment data of the Alligator Gar (1981–2010). A non-linear relationship existed between suitable spawning habitat area and the flow regime, with the most habitat availability corresponding to the 10–20-year flood recurrence interval frequency with peak flows of 2057–3108 m3s−1, respectively. The Alligator Gar recruitment data indicated that six years provided high recruitment, which correlated with peak flows of ~5-year frequency with an available spawning area of ~9000 Ha, moderate recruitment years related to peak flows with ~3-year frequency with an available spawning area of 6000 Ha, and low recruitment years where spawning was likely to occur at least every other year with at least 2500 Ha of available spawning area. The results of this model support the development of legislatively mandated environmental flow standards for the Guadalupe River Basin, inform field-based efforts for collecting empirical and observational data on the species’ reproduction, and provide spatial and temporal information for designing conservation strategies for Alligator Gar.

10.3390/hydrology10060123

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Citations (5)

Discrete return lidar-based prediction of leaf area index in two conifer forests

Remote Sensing of Environment (2008)

Jennifer Jensen K. S. Humes Lee A. Vierling Andrew T. Hudak

10.1016/j.rse.2008.07.001

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Citations (157)