Augmentation and Use of WRF-Hydro to Simulate Overland Flow- and Streamflow-Generated Debris Flow Hazards in Burn Scars

In steep wildfire-burned terrains, intense rainfall can produce large volumes of runoff that can trigger highly destructive debris flows. The ability to accurately characterize and forecast debris-flow hazards in burned terrains, however, remains limited. Here, we augment the Weather Research and Forecasting Hydrological modeling system (WRF-Hydro) to simulate both overland and channelized flows and assess postfire debris-flow hazards over a regional domain. We perform hindcast simulations using high-resolution weather radar-derived precipitation and reanalysis data to drive non-burned baseline and burn scar sensitivity experiments. Our simulations focus on January 2021 when an atmospheric river triggered numerous debris flows within a wildfire burn scar in Big Sur – one of which destroyed California’s famous Highway 1. Compared to the baseline, our burn scar simulation yields dramatic increases in total and peak discharge, and shorter lags between rainfall onset and peak discharge. At Rat Creek, where Highway 1 was destroyed, discharge volume increases eight-fold and peak discharge triples relative to the baseline. For all catchments within the burn scar, we find that the median catchment-area normalized discharge volume increases nine-fold after incorporating burn scar characteristics, while the 95th percentile volume increases 13-fold. Catchments with anomalously high hazard levels correspond well with post-event debris flow observations. Our results demonstrate that WRF-Hydro provides a compelling new physics-based tool to investigate and potentially forecast postfire hydrologic hazards at regional scales.

Undifferentiated Pleomorphic Sarcoma of a Chronic Burn Scar of the Knee With Lymph Node Metastasis

Malignant transformation of chronic burn scars are usually toward cutaneous lineages, including squamous cell carcinoma, basal cell carcinoma, and malignant melanoma. Sarcomas are less common. Undifferentiated pleomorphic sarcoma(UPS) is a subtype of soft tissue sarcoma with storiform-pleomorphic cells of uncertain origin, and has sparingly been reported to arise from burn scars. The majority are localized lesions probably due to the spatial distance of mesenchymal cells from the epithelium. The authors describe a rare case of UPS of the chronic burn scar of his knee with ipsilateral femoral and external iliac lymph node metastasis.

Wildfire burn scar encapsulation

Wildfires burn annually across the United States (US), which threaten those in close proximity to them. Due to drastic alterations of soil properties and to the land surfaces by these fires, risks of flash floods, debris flows, and severe erosion increases for these areas, which can have catastrophic consequences for biota, people and property. Computational tools, such as the WildfireRain algorithm, have been designed and implemented to assess the potential occurrence of debris flows over burn scars. However, in order to efficiently operate these tools, they require independent, non-overlapping buffers around burned areas to be defined, which is not a trivial task. In this paper we consider the problem of efficiently subsetting the conterminous US (CONUS) domain into optimal subdomains around burn scars, aiming to enable domain-wide WildfireRain product outputs to be used for operations by the National Weather Service (NWS). To achieve this, we define the Object Encapsulation Problem, where burn scars are represented by single-cell objects in a gridded domain, and circular buffers must be constructed around them. We propose a Linear Programming (LP) model that solves this problem efficiently. Optimal results produced using this model are presented for both a simplified synthetic data set, as well as for a subset of burn scars produced by severe wildfires in 2012 over the CONUS.

Assessing Burned Areas in Wildfires and Prescribed Fires with Spectral Indices and SAR Images in the Margalla Hills of Pakistan

The extent of wildfires cannot be easily mapped using field-based methods in areas with complex topography, and in those areas the use of remote sensing is an alternative. This study first obtained images from the Sentinel-2 satellites for the period 2015–2020 with the objective of applying multi-temporal spectral indices to assess areas burned in wildfires and prescribed fires in the Margalla Hills of Pakistan using the Google Earth Engine (GEE). Using those images, the Normalized Difference Vegetation Index (NDVI) and the Normalized Burn Ratio (NBR), which are often used to assess the severity of fires, were calculated for wildfires and prescribed fires. For each satellite image, spectral indices values were extracted for the 5th, 20th, 40th, 60th, 80th and 95th percentiles of pixels of each burned area. Then, boxplots representing the distribution of these values were plotted for each satellite image to identify whether the regeneration time subsequent to a fire, also known as the burn scar, and the severity of the fire differed between the autumn and summer wildfires, and with prescribed fires. A statistical test revealed no differences for the regeneration time amongst the three categories of fires, but that the severity of summer wildfires was significantly different from that of prescribed fire, and this, for both indices. Second, SAR images were obtained from the Sentinel-1 mission for the same period as that of the optical imagery. A comparison of the response of 34 SAR variables with official data on wildfires and prescribed fires from the Capital Development Authority revealed that the 95th percentile of the Normalized Signal Ratio (NSR p_95) was found to be the best variable to detect fire events, although only 50% of the fires were correctly detected. Nonetheless, when the occurrence of fire events according to the SAR variable NSR p_95 was compared to that from the two spectral indices, the SAR variable was found to correctly identify 95% of fire events. The SAR variable NSR p_95 is thus a suitable alternative to spectral indices to monitor the progress of wildfires and assess their severity when there are limitations to the use of optical images due to cloud coverage or smoke, for instance.

Heat flow, heat capacity and thermal resistance of localized surfaces of the human body using a new calorimetric sensor

A non-invasive sensor equipped with a programmable thermostat has been developed to assess in vivo the heat flow transmitted by conduction from human skin to the sensor thermostat. This device enables the assessment of the thermal properties of a 2 × 2 cm2 skin surface with a thermal penetration depth of 3–4 mm. In this work, we report the thermal magnitudes recorded with this sensor in 6 different areas (temple, hand, abdomen, thigh, wrist and heel) of 6 healthy subjects of different genders and ages, which were measured under resting conditions. Heat flow and equivalent thermal resistance are proportionally related to each other and are highly variable in magnitude and different for each zone. The heat capacity is also different for each zone. The heat flow values varied from 362 ± 17 mW at the temple to 36 ± 12 mW at the heel for the same subject, when the sensor thermostat was set at 26 °C. The equivalent thermal resistance ranged from 23 ± 2 K W−1 in the volar area of the wrist to 52 ± 4 KW−1 in the inner thigh area. The heat capacity varies from 4.8 ± 0.4 J K−1 in the heel to 6.4 ± 0.2 J K−1 in the abdomen. These magnitudes were also assessed over a 2 × 1 cm2 second-degree burn scar in the volar area of the wrist. The scar area had 27.6 and 11.6% lower heat capacity and equivalent thermal resistance, respectively, allowing an increased heat flow in the injured area. This work is a preliminary study of the measurement capacity of this new instrument.

Update on the practice of splinting during acute burn admission from the ACT study

Introduction Burn scar contracture (BSC) is a common pathological outcome following burn injuries, leading to limitations in range of motion (ROM) of affected joints and impairment in function. Despite a paucity of research addressing its efficacy, static splinting of affected joints is a common preventative practice. A survey of therapists performed 25 years ago showed a widely divergent practice of splinting during the acute burn injury. We undertook this study to determine the current practice of splinting during the index admission for burn injuries. Methods This is a review of a subset of patients enrolled in the Burn Patient Acuity Demographics, Scar Contractures and Rehabilitation Treatment Related to Patient Outcome Study (ACT) database. ACT was an observational multicenter study conducted from 2010-2013. The most commonly splinted joints (elbow, wrist, knee and ankle) and their 7 motions were included. Variables included patients’ demographics, burn variables, rehabilitation treatment and hospital course details. Univariate and multivariate analysis of factors related to splinting was performed. P< 0.05 was significant. Results Thirty percent of the study population (75 patients) underwent splinting during their hospitalization. Splinting was associated with larger burns and increased injury severity on the patient level and increased involvement with burns requiring grafting in the associated cutaneous functional unit (CFU) on the joint level. The requirement for skin grafting in both analyses remained independently related to splinting, with requirement for grafting in the associated CFU increasing the odds of splinting 6 times (OR =6.0, 95% CI=3.8-9.3, p<0.001). On average splinting was initiated about a third into the hospital length of stay (LOS, 35 ± 21% of LOS) and splints were worn for 50% (50 ± 26%) of the LOS. Joints were splinted for an average 15.1 ± 4.8 hours a day. The wrist was most frequently splinted joint being splinted with one third of wrists splinted ( 30.7%) while the knee was the least frequently splinted joint with 8.2% splinted. However, when splinted, the knee was splinted the most hours per day (17.6 ± 4.8 hours) and the ankle the least (14.4 ± 4.6 hours). Almost one third had splinting continued to discharge (20, 27%). Conclusions The current practice of splinting, especially the initiation, hours of wear and duration of splinting following acute burn injury remains variable. Splinting is independently related to grafting, grafting in the joint CFU, larger CFU involvement and is more likely to occur around the time of surgery. A future study looking at splinting application and its outcomes is warranted.