scholarly journals Modeling Drying of Degenerated Calluna vulgaris for Wildfire and Prescribed Burning Risk Assessment

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 759 ◽  
Author(s):  
Torgrim Log
Keyword(s):  
Mathematical Model ◽  
Numerical Model ◽  
Mass Loss ◽  
Diffusion Coefficients ◽  
Prescribed Burning ◽  
Fire Hazard ◽  
Fire Risk ◽  
Calluna Vulgaris ◽  
Fire Danger ◽  
Drying Process

Research highlights: Moisture diffusion coefficients for stems and branches of degenerated Calluna vulgaris L. have been obtained and a mathematical model for the drying process has been developed and validated as an input to future fire danger modeling. Background and objectives: In Norway, several recent wildland–urban interface (WUI) fires have been attributed to climate changes and accumulation of elevated live and dead biomass in degenerated Calluna stands due to changes in agricultural activities, i.e., in particular abandonment of prescribed burning for sheep grazing. Prescribed burning is now being reintroduced in these currently fire prone landscapes. While available wildfire danger rating models fail to predict the rapidly changing fire hazard in such heathlands, there is an increasing need for an adapted fire danger model. The present study aims at determining water diffusion coefficients and develops a numerical model for the drying process, paving the road for future fire danger forecasts and prediction of safe and efficient conditions for prescribed burning. Materials and methods: Test specimens (3–6 mm diameter) of dead Calluna stems and branches were rain wetted 48 h and subsequently placed in a climate chamber at 20 °C and 50% relative humidity for mass loss recordings during natural convection drying. Based on the diameter and recorded mass versus time, diffusion coefficients were obtained. A numerical model was developed and verified against recoded mass loss. Results: Diffusion coefficients were obtained in the range 1.66–10.4 × 10−11 m2/s. This is quite low and may be explained by the very hard Calluna “wood”. The large span may be explained by different growth conditions, insect attacks and a varying number of years of exposure to the elements after dying. The mathematical model described the drying process well for the specimens with known diffusion coefficient. Conclusions: The established range of diffusion coefficients and the developed model may likely be extended for forecasting moisture content of degenerated Calluna as a proxy for fire danger and/or conditions for efficient and safe prescribed burning. This may help mitigate the emerging fire risk associated with degenerated Calluna stands in a changing climate.

scholarly journals Fire danger rating over Mediterranean Europe based on fire radiative power derived from Meteosat

2017 ◽  
Author(s):  
Miguel M. Pinto ◽  
Carlos C. DaCamara ◽  
Isabel F. Trigo ◽  
Ricardo M. Trigo ◽  
K. Feridun Turkman
Keyword(s):  
Land Surface ◽  
Management Practices ◽  
Prescribed Burning ◽  
Generalized Pareto Distribution ◽  
Fire Risk ◽  
Fire Danger ◽  
Radiative Energy ◽  
Fire Weather Index ◽  
Mediterranean Europe ◽  
Daily Energy

Abstract. We present a procedure that allows the operational generation of daily forecasts of fire danger over Mediterranean Europe aiming to improve state-of-the art modelling skills for classes of high fire danger. The procedure combines historical information about radiative energy released by fire events with daily meteorological forecasts, as provided by the Satellite Application Facility for Land Surface Analysis (LSA SAF) and the European Centre for Medium-Range Weather Forecasts (ECMWF). Fire danger is estimated based on daily probabilities of exceedance of daily energy released by fires occurring at the pixel level. Daily probability considers meteorological information by means of the Canadian Fire Weather Index (FWI) and is estimated using a Daily Model based on a Generalized Pareto distribution. Five classes of fire danger are then associated to daily probability estimated by the Daily Model. The model is calibrated using seven years of data (2010–2016) and validated against the period of January–August 2017. Results obtained show that about 80 % of events releasing daily energy above 10 000 GJ belong to the Extreme class of fire danger, a considerably high fraction that is more than the double of the values obtained when using the currently operational Fire Danger Forecast module of the European Forest Fire Information System (EFFIS) or the Fire Risk Map (FRM) product disseminated by the LSA SAF. Besides assisting in wildfire management, the procedure is expected to help in decision making on prescribed burning within the framework of agricultural and forest management practices.

Integrating new methods and tools in fire danger rating

2007 ◽  
Vol 16 (3) ◽  
pp. 306 ◽  
Author(s):  
Christos Vasilakos ◽  
Kostas Kalabokidis ◽  
John Hatzopoulos ◽  
George Kallos ◽  
Yiannis Matsinos
Keyword(s):  
Fire Hazard ◽  
Meteorological Data ◽  
Risk Index ◽  
Hazard Index ◽  
Fire Risk ◽  
Fire Danger ◽  
Burned Area ◽  
Fire Weather Index ◽  
Input Parameters ◽  
Fire Ignition

Prevention is one of the most important stages in wildfire and other natural hazard management regimes. Fire danger rating systems have been adopted by many developed countries dealing with wildfire prevention and pre-suppression planning, so that civil protection agencies are able to define areas with high probabilities of fire ignition and resort to necessary actions. This present paper presents a fire ignition risk scheme, developed in the study area of Lesvos Island, Greece, that can be an integral component of a quantitative Fire Danger Rating System. The proposed methodology estimates the geo-spatial fire risk regardless of fire causes or expected burned area, and it has the ability of forecasting based on meteorological data. The main output of the proposed scheme is the Fire Ignition Index, which is based on three other indices: Fire Weather Index, Fire Hazard Index, and Fire Risk Index. These indices are not just a relative probability for fire occurrence, but a rather quantitative assessment of fire danger in a systematic way. Remote sensing data from the high-resolution QuickBird and the Landsat ETM satellite sensors were utilised in order to provide part of the input parameters to the scheme, while Remote Automatic Weather Stations and the SKIRON/Eta weather forecasting system provided real-time and forecasted meteorological data, respectively. Geographic Information Systems were used for management and spatial analyses of the input parameters. The relationship between wildfire occurrence and the input parameters was investigated by neural networks whose training was based on historical data.

scholarly journals Fire danger rating over Mediterranean Europe based on fire radiative power derived from Meteosat

2018 ◽  
Vol 18 (2) ◽  
pp. 515-529 ◽  
Author(s):  
Miguel M. Pinto ◽  
Carlos C. DaCamara ◽  
Isabel F. Trigo ◽  
Ricardo M. Trigo ◽  
K. Feridun Turkman
Keyword(s):  
Land Surface ◽  
Management Practices ◽  
Prescribed Burning ◽  
Generalized Pareto Distribution ◽  
Fire Risk ◽  
Fire Danger ◽  
Radiative Energy ◽  
Fire Weather Index ◽  
Mediterranean Europe ◽  
Daily Energy

Abstract. We present a procedure that allows the operational generation of daily forecasts of fire danger over Mediterranean Europe. The procedure combines historical information about radiative energy released by fire events with daily meteorological forecasts, as provided by the Satellite Application Facility for Land Surface Analysis (LSA SAF) and the European Centre for Medium-Range Weather Forecasts (ECMWF). Fire danger is estimated based on daily probabilities of exceedance of daily energy released by fires occurring at the pixel level. Daily probability considers meteorological factors by means of the Canadian Fire Weather Index (FWI) and is estimated using a daily model based on a generalized Pareto distribution. Five classes of fire danger are then associated with daily probability estimated by the daily model. The model is calibrated using 13 years of data (2004–2016) and validated against the period of January–September 2017. Results obtained show that about 72 % of events releasing daily energy above 10 000 GJ belong to the “extreme” class of fire danger, a considerably high fraction that is more than 1.5 times the values obtained when using the currently operational Fire Danger Forecast module of the European Forest Fire Information System (EFFIS) or the Fire Risk Map (FRM) product disseminated by the LSA SAF. Besides assisting in wildfire management, the procedure is expected to help in decision making on prescribed burning within the framework of agricultural and forest management practices.

Mathematical Models of Papermaking

2001 ◽  
Vol 6 (1) ◽  
pp. 9-19 ◽  
Author(s):  
A. Buikis ◽  
J. Cepitis ◽  
H. Kalis ◽  
A. Reinfelds ◽  
A. Ancitis ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Initial Value Problems ◽  
Moisture Transfer ◽  
Bound Water ◽  
Drying Process ◽  
Initial Value ◽  
First Order ◽  
Heat And Moisture ◽  
The Mathematical Model ◽  
The Web

The mathematical model of wood drying based on detailed transport phenomena considering both heat and moisture transfer have been offered in article. The adjustment of this model to the drying process of papermaking is carried out for the range of moisture content corresponding to the period of drying in which vapour movement and bound water diffusion in the web are possible. By averaging as the desired models are obtained sequence of the initial value problems for systems of two nonlinear first order ordinary differential equations. 

The mathematical modelling of corrosion in hot dip galvanized steel reinforced concrete

2011 ◽  
Vol 2 (1) ◽  
pp. 1-12
Author(s):  
A. Hegyi ◽  
H. Vermeşan ◽  
V. Rus
Keyword(s):  
Mathematical Model ◽  
Reinforced Concrete ◽  
Numerical Model ◽  
Equation System ◽  
Galvanized Steel ◽  
Steel Reinforced Concrete ◽  
Numeric Model ◽  
Physical And Mathematical Models ◽  
Physical Phenomena ◽  
The Mathematical Model

Abstract In this paper we wish to present the numerical model elaborated in order to simulate some physical phenomena that influence the general deterioration of steel, whether hot dip galvanized or not, in reinforced concrete. We describe the physical and mathematical models, establishing the corresponding equation system, the initial and boundary conditions. We have also presented the numeric model associated to the mathematical model and the numeric methods of discretization and solution of the differential equations system that describes the mathematical model.

scholarly journals Prescribed burning in a mediterranean-climate region mitigates the disturbance by bushfire to a critical food resource for an endangered bird, the Carnaby’s cockatoo

Fire Ecology ◽  
2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Valerie S. Densmore ◽  
Emma S. Clingan
Keyword(s):  
Seed Production ◽  
Prescribed Burning ◽  
Fire Regime ◽  
Fire Hazard ◽  
Food Resource ◽  
Management Tool ◽  
Fire Intensity ◽  
Prescribed Burns ◽  
Low Intensity ◽  
Percentage Survival

Abstract Background Prescribed burning is used to reduce fire hazard in highly flammable vegetation types, including Banksia L.f. woodland that occurs on the Swan Coastal Plain (SCP), Western Australia, Australia. The 2016 census recorded well over 1.9 million people living on the SCP, which also encompasses Perth, the fourth largest city in Australia. Banksia woodland is prone to frequent ignitions that can cause extensive bushfires that consume canopy-stored banksia seeds, a critical food resource for an endangered bird, the Carnaby’s cockatoo (Calyptorynchus latirostris, Carnaby 1948). The time needed for banksias to reach maturity and maximum seed production is several years longer than the typical interval between prescribed burns. We compared prescribed burns to bushfires and unburned sites at three locations in banksia woodland to determine whether low-intensity prescribed burns affect the number of adult banksias and their seed production. Study sites were matched to the same vegetation complex, fire regime, and time-since-fire to isolate fire intensity as a variable. Results Headfire rates of spread and differenced normalized burn ratios indicated that prescribed burning was generally of a much lower intensity than bushfire. The percentage survival of adult banksias and their production of cones and follicles (seeds) did not decrease during the first three years following a prescribed burn. However, survival and seed production were significantly diminished followed high-intensity bushfire. Thus, carrying capacity for Carnaby’s cockatoo was unchanged by prescribed burning but decreased markedly following bushfire in banksia woodland. Conclusions These results suggest that prescribed burning is markedly different from bushfire when considering appropriate fire intervals to conserve canopy habitats in fire-resilient vegetation communities. Therefore, low-intensity prescribed burning represents a viable management tool to reduce the frequency and extent of bushfire impacts on banksia woodland and Carnaby’s cockatoo.

scholarly journals Quantitative Analysis of Forest Fires in Southeastern Australia Using SAR Data

2021 ◽  
Vol 13 (12) ◽  
pp. 2386
Author(s):  
Aqil Tariq ◽  
Hong Shu ◽  
Qingting Li ◽  
Orhan Altan ◽  
Mobushir Riaz Khan ◽  
...  
Keyword(s):  
Forest Fires ◽  
Prescribed Burning ◽  
Fire Risk ◽  
Fire Season ◽  
Prescribed Burn ◽  
Backscatter Coefficient ◽  
Prescribed Burns ◽  
Southeastern Australia ◽  
Sar Data ◽  
Sar Imagery

Prescribed burning is a common strategy for minimizing forest fire risk. Fire is introduced under specific environmental conditions, with explicit duration, intensity, and rate of spread. Such conditions deviate from those encountered during the fire season. Prescribed burns mostly affect surface fuels and understory vegetation, an outcome markedly different when compared to wildfires. Data on prescribed burning are crucial for evaluating whether land management targets have been reached. This research developed a methodology to quantify the effects of prescribed burns using multi-temporal Sentinel-1 Synthetic Aperture Radar (SAR) imagery in the forests of southeastern Australia. C-band SAR datasets were specifically used to statistically explore changes in radar backscatter coefficients with the intensity of prescribed burns. Two modeling approaches based on pre- and post-fire ratios were applied for evaluating prescribed burn impacts. The effects of prescribed burns were documented with an overall accuracy of 82.3% using cross-polarized backscatter (VH) SAR data under dry conditions. The VV polarization indicated some potential to detect burned areas under wet conditions. The findings in this study indicate that the C-band SAR backscatter coefficient has the potential to evaluate the effectiveness of prescribed burns due to its sensitivity to changes in vegetation structure.

Study on Drying Characteristics of Microalgae under Different Conditions

2013 ◽  
Vol 724-725 ◽  
pp. 296-299
Author(s):  
Chun Xiang Chen ◽  
Xiao Qian Ma ◽  
Xiao Cong Li ◽  
Wei Ping Qin
Keyword(s):  
Moisture Content ◽  
Mass Loss ◽  
Fresh Water ◽  
Chlorella Vulgaris ◽  
Drying Process ◽  
Drying Time ◽  
Drying Characteristics ◽  
Second Stage ◽  
Drying System ◽  
Two Stages

To find out an alternative of coal saving, a kind of microalgae, Chlorella vulgaris (C. vulgaris) which is widespread in fresh water was studied by digital blast drying system. The effect of the moisture content, drying thickness and temperature on the drying process of C. vulgaris were investigated. The results indicated that when the drying temperature is high, the moisture content is low and the material thickness is small, the drying time is short. The drying process of C.vulgaris can be divided into two stages, and the mass loss is mainly occurred in the second stage . The results will provide guidance for design of drying process and dryer of microalgae.

Homogeneous–Heterogeneous Reactions of Blasius Flow in a Nanofluid

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Hang Xu
Keyword(s):  
Mathematical Model ◽  
Diffusion Coefficients ◽  
Multiple Solutions ◽  
Transport Mechanism ◽  
Heterogeneous Reactions ◽  
Nonlinear Ordinary Differential Equations ◽  
Blasius Flow ◽  
Homogeneous And Heterogeneous Reactions ◽  
Heterogeneous Chemical ◽  
Heterogeneous Chemical Reactions

An investigation is made to study the Blasius flow of a nanofluid in the presence of homogeneous–heterogeneous chemical reactions. Here, the diffusion coefficients of the reactant and autocatalyst are considered to be in comparable sizes. The Buongiorno's mathematical model is applied in describing the behavior of nanofluids. Multiple solutions of the steady-state system of nonlinear ordinary differential equations are obtained. Results show that nanofluids significantly participate in the transport mechanism of the homogeneous–heterogeneous reactions, which play different roles in the procedures of homogeneous and heterogeneous reactions.

Microbial biomass and activity in the humus layer following burning: short-term effects of two different fires

1993 ◽  
Vol 23 (7) ◽  
pp. 1275-1285 ◽  
Author(s):  
Janna Pietikäinen ◽  
Hannu Fritze
Keyword(s):  
Microbial Community ◽  
Microbial Biomass ◽  
Soil Respiration ◽  
Mass Loss ◽  
Forest Fire ◽  
Prescribed Burning ◽  
Microbial Biomass C ◽  
Soil Microbial ◽  
Fungal Hyphae ◽  
C And N

During a 3-year study, soil microbial biomass C and N, length of the fungal hyphae, soil respiration, and the percent mass loss of needle litter were recorded in coniferous forest soil humus layers following a prescribed burning (PB) treatment or a forest fire simulation (FF) treatment (five plots per treatment). Unburned humus from adjacent plots served as controls (PC and FC, respectively). Prescribed burning was more intensive than the forest fire, and this was reflected in all the measurements taken. The amounts of microbial biomass C and N, length of fungal hyphae, and soil respiration in the PB area did not recover to their controls levels, whereas unchanged microbial biomass N and recovery of the length of the fungal hyphae to control levels were observed in the FF area. The mean microbial C/N ratio was approximately 7 in all the areas, which reflected the C/N ratio of the soil microbial community. Deviation from this mean value, as observed during the first three samplings from the PB area (3, 18, and 35 days after fire treatment), suggested a change in the composition of the microbial community. Of the two treated areas, the decrease in soil respiration (laboratory measurements) was much more pronounced in the PB area. However, when the humus samples from both areas were adjusted to 60% water holding capacity, no differences in respiration capacity were observed. The drier humus, due to higher soil temperatures, of the PB area is a likely explanation for the low soil respiration. Lower soil respiration was not reflected in lower litter decomposition rates of the PB area, since there was a significantly higher needle litter mass loss during the first year in the PB area followed by a decline to the control level during the second year. Consistently higher mass losses were recorded in the FC area than in the FF area.

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