Geology topics

R. Luna

Publications and source records attributed to R. Luna.

3 recordsLinked to original sources

USGS2013

Remote sensing of soil moisture using airborne hyperspectral data

Landscape assessment of soil moisture is critical to understanding the hydrological cycle at the regional scale and in broad-scale studies of biophysical processes affected by global climate changes in temperature and precipitation. Traditional efforts to measure soil moisture have been principally restricted to in situ measurements, so remote sensing techniques are often employed. Hyperspectral sensors with finer spatial resolution and narrow band widths may offer an alternative to traditional multispectral analysis of soil moisture, particularly in landscapes with high spatial heterogeneity. This preliminary research evaluates the ability of remotely sensed hyperspectral data to quantify soil moisture for the Little River Experimental Watershed (LREW), Georgia. An airborne hyperspectral instrument with a short-wavelength infrared (SWIR) sensor was flown in 2005 and 2007 and the results were correlated to in situ soil moisture values. A significant statistical correlation ( R 2 value above 0.7 for both sampling dates) for the hyperspectral instrument data and the soil moisture probe data at 5.08 cm (2 inches) was determined. While models for the 20.32 cm (8 inches) and 30.48 cm (12 inches) depths were tested, they were not able to estimate soil moisture to the same degree.

GIScience and Remote Sensing↗

USGS2007

Chemical quality of depositional sediments and associated soils in New Orleans and the Louisiana peninsula following Hurricane Katrina

Hurricane Katrina made landfall on the Louisiana peninsula south of New Orleans on Aug 29, 2005. The resulting storm surge caused numerous levy breaches in the parishes of New Orleans as well as on the Louisiana peninsula. This study was conducted to determine the concentrations of inorganic and organic constituents in sediments and associated soils in New Orleans parishes and the Louisiana peninsula after the floodwaters had been removed and/or receded following Hurricane Katrina. A total of 46 sediment and soil samples were analyzed that were collected throughout New Orleans and the Louisiana peninsula. Approximately 20% of the sediment samples were analyzed, including shallow sediment samples from locations that included the top and beneath automobiles, in residential and commercial areas, and near refineries. Gasoline constituents, pesticides, and leachable heavy metals were analyzed using headspace gas chromatography/mass spectrometry (GC/MS), organic extraction GC/MS, and inductively coupled plasma/mass spectrometry, respectively. A significant number of samples had leachable As and Pb concentrations in excess of drinking water standards. The remaining metals analyzed (i.e., Cd, Cr, Cu, Hg, and V) generally had much lower leachable levels. Of the gasoline constituents, only benzene was observed above the limit of detection (of 5 ??g/kg), with no samples observed as being above the method detection limits of 10 ??g/kg. For the 18 pesticides analyzed, most were in the nondetectable range and all were in trace amounts that were orders of magnitude below regulatory guidelines. ?? 2007 American Chemical Society.

Environmental Science & Technology↗

USGS1997

Spatial earthquake hazard assessment of Evansville, Indiana

The earthquake hazard has been evaluated for a 150-square-kilometer area around Evansville, Indiana. GIS-QUAKE, a system that combines liquefaction and ground motion analysis routines with site-specific geological, geotechnical, and seismological information, was used for the analysis. The hazard potential was determined by using 586 SPT borings, 27 CPT sounding, 39 shear-wave velocity profiles and synthesized acceleration records for body-wave magnitude 6.5 and 7.3 mid-continental earthquakes, occurring at distances of 50 km and 250 km, respectively. The results of the GIS-QUAKE hazard analyses for Evansville identify areas with a high hazard potential that had not previously been identified in earthquake zonation studies. The Pigeon Creek area specifically is identified as having significant potential for liquefaction-induced damage. Damage as a result of ground motion amplification is determined to be a moderate concern throughout the area. Differences in the findings of this zonation study and previous work are attributed to the size and range of the database, the hazard evaluation methodologies, and the geostatistical interpolation techniques used to estimate the hazard potential. Further, assumptions regarding the groundwater elevations made in previous studies are also considered to have had a significant effect on the results.

Indiana↗