Geology topics

Orlando C. Romero

Publications and source records attributed to Orlando C. Romero.

3 recordsLinked to original sources

USGS2018

Thresholds and relations for soil‐hydraulic and soil‐physical properties as a function of burn severity 4 years after the 2011 Las Conchas Fire, New Mexico, USA

Wildfire effects on soil‐physical and ‐hydraulic properties as a function of burn severity are poorly characterized, especially several years after wildfire. A stratified random sampling approach was used in 2015 to sample seven sites representing a spectrum of remotely sensed burn severity in the area impacted by the 2011 Las Conchas Fire in New Mexico, USA. Replicate samples from each site were analysed in the laboratory. Linear and linear indicator regression were used to assess thresholds in soil‐physical and ‐hydraulic properties and functional relations with remotely sensed burn severity. Significant thresholds were present for initial soil‐water content (θ i ) at 0–6 cm depth between the change in the Normalized Burn Ratio ( dNBR ) equal to 618–802, for bulk density (ρ b ) at 3–6 cm between dNBR equal to 416–533, for gravel fraction at 0–1 cm between dNBR equal to 416–533, for fines (the silt + clay fraction) at 0–1 cm for dNBR equal to 416–533, and for fines at 3–6 cm for dNBR equal to 293–416. Significant linear relations with dNB R were present between ρ b at 0–1 cm, loss on ignition (LOI) at 0–1 cm, gravel fraction at 0–1 cm, and the large organic fraction at 1–3 cm. No thresholds or effects on soil‐hydraulic properties of field‐saturated hydraulic conductivity or sorptivity were observed. These results suggest that ρ b and LOI at 0–1 cm have residual direct impacts from the wildfire heat impulse. The θ i threshold is most likely from delayed groundcover/vegetation recovery that increases evaporation at the highest burn severity sites. Gravel and silt + clay thresholds at 0–1 cm at the transition to high burn severity suggest surface gravel lag development from hydraulic erosion. Thresholds in ρ b from 3 to 6 cm and in silt + clay fraction from 3 to 6 cm appear to be the result of soil variability between sites rather than wildfire impacts. This work suggests that gravel‐rich soils may have increased resilience to sustained surface runoff generation and erosion following wildfire, with implications for assessments of postwildfire hydrologic and erosion recovery potential.

New Mexico↗

USGS2018

Postwildfire measurement of soil physical and hydraulic properties at selected sampling sites in the 2011 Las Conchas wildfire burn scar, Jemez Mountains, north-central New Mexico

The generation of runoff and the resultant flash flooding can be substantially larger following wildfire than for similar rainstorms that precede wildfire disturbance. Flash flooding after the 2011 Las Conchas Fire in New Mexico provided the motivation for this investigation to assess postwildfire effects on soil-hydraulic properties (SHPs) and soil-physical properties (SPPs) as a function of remotely sensed burn severity 4 years following the wildfire. A secondary purpose of this report is to illustrate a methodology to determine SHPs that analyzes infiltrometer data by using three different analysis methods. The SPPs and SHPs are measured as a function of remotely sensed burn severity by using the difference in the Normalized Burn Ratio (dNBR) metric for seven sites. The dNBR metric was used to guide field sample collection across a full spectrum of burn severities that covered the range of Monitoring Trends in Burn Severity (MTBS) and Burned Area Reflectance Classification (BARC) thematic classes from low to high severity. The SPPs (initial and saturated soil-water content, bulk density, soil-organic matter, and soil-particle size) and SHPs (field-saturated hydraulic conductivity and sorptivity) were measured under controlled laboratory conditions for soil cores collected in the field. The SHPs were estimated by using tension infiltrometer measurements and three different data analysis methods. These measurements showed large effects of burn severity, focused in the top 1 centimeter (cm) of soil, on some SPPs (bulk density, soil organic matter, and particle sizes). The threshold of these bulk density and soil organic matter effects was between 300 and 400 dNBR, which corresponds to a MTBS thematic class between moderate and high burn severity and a BARC4 thematic class of high severity. Gravel content and the content of fines in the top 1 cm of soil had a higher threshold value between 450 and 500 dNBR. Lesser effects on SPPs were observed at depths of 1–3 cm and 3–6 cm. In contrast, SHPs showed little effect from dNBR or from MTBS/BARC4 thematic class. Measurements suggested that 4 years of elapsed time after the wildfire may be sufficient for SHP recovery in this area. These measurements also indicated that SPP differences as a function of burn severity cannot be used as reliable indicators of SHP differences as a function of burn severity.

New Mexico↗

USGS2015

Summary of urban stormwater quality in Albuquerque, New Mexico, 2003-12

Urban stormwater in the Albuquerque metropolitan area was sampled by the U.S. Geological Survey in cooperation with the City of Albuquerque, the Albuquerque Metropolitan Arroyo Flood Control Authority, the New Mexico Department of Transportation, and the University of New Mexico. Stormwater was sampled from a network of monitoring stations from 2003 to 2012 by following regulatory requirements for the National Pollutant Discharge Elimination System stormwater permit. During this period, stormwater was sampled in the Albuquerque metropolitan area at outfalls from nine drainage basins with residential, industrial, commercial, agricultural, and undeveloped land uses. Stormwater samples were analyzed for selected physical and chemical characteristics, nutrients, major ions, metals, organic compounds, and bacteria. General quality of stormwater samples, as measured by dissolved solids, nutrient (with the exception of phosphorus), major ion, and dissolved metal concentrations, was similar to that in samples from the Rio Grande. Of the nearly 200 organic compounds that were analyzed for this study, less than one-third (58 constituents) were positively identified at or above the analytical detection limit in stormwater. Concentrations for volatile organic compounds, semivolatile organic compounds, polychlorinated biphenyls, and pesticides were generally low in the stormwater samples. Fifteen of the 16 polycyclic aromatic hydrocarbons listed on the U.S. Environmental Protection Agency Priority Chemicals list were detected in at least one stormwater sample from each outfall. Maximum concentrations for some polycyclic aromatic hydrocarbons in stormwater did exceed a water-quality criterion. Median concentrations for Escherichia coli ( E. coli ) bacteria in the stormwater samples, including those from the background location (Embudo Arroyo), were above the New Mexico water-quality standard. Concentrations for E. coli in stormwater often exceeded the water-quality criterion. The stormwater quality in Albuquerque was compared with that of six other Western U.S. cities (Phoenix, Arizona; Tucson, Arizona; Las Vegas, Nevada; Denver, Colorado; Salt Lake City, Utah; and Boise, Idaho) for selected constituents. In general, water-quality data for stormwater samples from these six other Western U.S. cities were similar to water-quality data for the stormwater samples from the Albuquerque outfalls. Median concentrations for suspended solids, total phosphorus, and bacteria ( E. coli and fecal coliform) in stormwater samples from the Albuquerque outfalls, as a whole, were higher than those in samples from the other Western U.S. cities except for Las Vegas.

New Mexico↗