Low watershed hydrological and erosion response after fire can be explained by connectivity

2020 ◽  
Author(s):  
Jinfeng Wu ◽  
Jantiene E.M. Baartman ◽  
João P. Nunes
Keyword(s):  
Overland Flow ◽  
Burn Severity ◽  
Watershed Scale ◽  
Hydrological Responses ◽  
Erosion Processes ◽  
Altered Hydrology ◽  
Sediment Loads ◽  
Before And After ◽  
Mediterranean Regions ◽  
Major Factors

<p>Mediterranean regions have always been affected by wildfires. However, no studies investigating post-fire hydrological responses and erosion at the watershed scale (~>10 km2) were conducted in Mediterranean. In this study, the discharge and sediment measurements at the outlet of a Mediterranean watershed were observed to test changes in hydrological responses and sediment loads before and after the fire. Besides, aid by the PCA analysis and analysis of connectivity patterns and changes using the index of connectivity (IC), we analyze the hydrological responses and erosion to a wildfire at the watershed scale. Although most of vegetation was removed after the wildfire, it did not, overall, lead to a significant increase in hydrological responses and sediment loads at the watershed scale. Our results can be explained by three major factors. Firstly, much lower rainfall the first two hydrological years after the fire occurred in our watershed. Secondly, as a result of the scale dependency of hydrological and erosion processes, fire-enhanced overland flow and sediment transport occurred locally on hillslope with high burn severity but did not (yet) reach the outlet. Finally, and arguably, most importantly, connectivity in our study area is relatively low and, although it increases after the fire, it remains generally low. Even though post-wildfire connectivity in our watershed increased by 20%, this increase in connectivity was mainly located in the upstream-most part of this catchment, with much less increased connectivity in the downstream areas, which are closer to the catchment outlet. We concluded that the fire consumed vegetation and altered hydrology and erosion processes but didn’t significantly influence downstream water quantity and quality. Connectivity linked to burn severity was suitable for evaluating the effect of wildfire on hydrological responses and erosion. Moreover, this method also appears to be reasonable in assessing and mitigating post-fire water contamination risk.</p>

scholarly journals Hydrogeomorphic processes affecting dryland gully erosion: Implications for modelling

2018 ◽  
Vol 43 (1) ◽  
pp. 46-64 ◽  
Author(s):  
Roy C. Sidle ◽  
Ben Jarihani ◽  
SanLinn Ismail Kaka ◽  
Jack Koci ◽  
Abdulaziz Al-Shaibani
Keyword(s):  
Land Management ◽  
Management Practices ◽  
Overland Flow ◽  
Ground Cover ◽  
Gully Erosion ◽  
Annual Rainfall ◽  
Surface Erosion ◽  
Distributed Data ◽  
Erosion Processes ◽  
Sediment Loads

Gullies contribute high sediment loads to receiving waters and significantly degrade landscapes. In drylands, low annual rainfall and resultant poor ground cover, coupled with high-intensity storms and dispersive soils, predispose these landscapes to gully erosion. Land management, such as grazing, exacerbates gully-forming processes by degrading ground cover and compacting soils, thereby increasing and concentrating overland flow. Current surface erosion models do not adequately represent sediment export from gullied terrain due to lack of distributed data and complex hydrogeomorphic processes, such as overland flow concentration, waterfall erosion, soil pipe collapse, and mass wasting. Here, we outline the strengths and weaknesses of past modelling approaches in erodible terrain and focus on how gully erosion processes can be better simulated at appropriate scales using newly available remote-sensing techniques and databases, coupled with improved understanding of relevant hydrogeomorphic processes. We also discuss and present examples of challenges related to assessing land management practices in drylands that affect gully erosion.

Abstract 683: Regression of Plaque Volume in One Arterial Bed is not Necessarily Associated with Similar Changes in Other Vessels

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Takayuki Suzuki ◽  
Takashi Nozawa ◽  
Mitsuo Sobajima ◽  
Takashi Ohori ◽  
Akira Matsuki ◽  
...  
Keyword(s):  
Population Based ◽  
Plaque Volume ◽  
Independent Variables ◽  
Before And After ◽  
Independent Variable ◽  
Artery Disease ◽  
Soft Plaque ◽  
Major Factors ◽  
Atherosclerotic Changes

Background: Population-based studies have shown good correlation between severity of atherosclerotic disease in one arterial bed and involvement of other vessels. However, in patients with coronary artery disease (CAD), it remains unclear whether atherosclerotic plaque in an artery might regress or progress in parallel with other vessels. Accordingly, the present study was performed in patients with CAD to compare changes in plaque volume (PV) between the left main (LMT) and right coronary arteries (RCA), thoracic descending aorta (TDA) and common carotid artery (CCA), and to clarify clinical factors and biomarkers which might affect changes in PV in each artery. Methods: Using 64-multislice computed tomography, PVs in each artery were determined before and after 2.0-year follow-up period in 52 patients with CAD (67.4±9.9yo). Based on our previous study using ultrasound, CCA-PV was determined at windows of 90–240HU and TDA-PV determined manually. Coronary soft plaque was determined at windows of 0–75HU. Plasma levels of hsCRP, matrix metalloproteinase (MMP)-9 and urinary 8-iso-prostaglandin F2 α (PGF) were determined at baseline. Results: At baseline, PVs of TDA were correlated with CCA-PV (r=0.38, p<0.02), but PVs of other arteries did not correlate to each other. Two-year later, PVs of LMT, RCA, TDA, and CCA were reduced in 41, 62, 27, and 39% of patients, respectively. Changes in LMT-PV were weakly related with those of TDA-PV (r=0.37, p=0.02) and RCA-PV (r=0.31, p=0.08), but there were no relation between other arteries. The multivariate analysis revealed that treatment with statin and low LDL-cholesterol (C, <100mg/dl) were independent variables regarding a reduction in DTA-PV, but, in LMT, only low LDL-C was independent variable. However, there were no independent variables in RCA or CCA. The ratio of soft PV to total PV was similar between LMT (45.2±7.1%) and RCA (45.7±4.9%) at baseline and was unchanged in the follow-up study. None of hsCRP, MMP-9 or PGF levels was related with PVs of any arteries at baseline and with changes in PVs. Conclusions: Regression of PV in one arterial bed dose not necessarily allow us to predict atherosclerotic changes in the other vessels. Major factors which affect changes in PV may not be homogeneous between arteries.

Evaluation of Bacterial Contamination on Prehospital Ambulances Before and After Disinfection

2018 ◽  
Vol 33 (6) ◽  
pp. 602-606
Author(s):  
Roohollah Farhadloo ◽  
Jalil Goodarzi Far ◽  
Mohammad Reza Azadeh ◽  
Saeed Shams ◽  
Mohammad Parvaresh-Masoud
Keyword(s):  
Nosocomial Infections ◽  
Bacterial Contamination ◽  
Microbial Contamination ◽  
Contamination Level ◽  
Publication Type ◽  
Bacterial Agent ◽  
Before And After ◽  
Quasi Experimental ◽  
Effective Role ◽  
Major Factors

AbstractBackgroundThe contamination of the environment, ambulance equipment, and staff hands consequently are major factors which create nosocomial infections in emergency patients. The contamination of equipment and devices plays an important role in nosocomial infections.ObjectivesThe aim of this study was to determine the effectiveness of a disinfectant on the rate of microbial contamination of ambulances in Qom Emergency Medical Services (EMS), Qom, Iran.MethodsThis is a quasi-experimental study with a before-after design in order to determine microbial contaminations at the rear and front cabin of ambulances, as well as medical equipment being utilized in Qom EMS. Saya sept-HP-2% solution was used for disinfection. Bacteriological standard methods were used to identify the contaminations.ResultsThe contamination rates before and after use of disinfection solution were 52% and eight percent, respectively. Coagulase-negative staphylococci were the most commonly isolated bacterial agent from the equipment (53%). In all equipment, the contamination level has shown a significant reduction after applying disinfectant.Conclusions:In spite of the fact that the rate of infection from ambulance equipment is high, the results showed that the use of the suitable disinfectant had an effective role in the reduction of bacteria.FarhadlooR, Goodarzi FarJ, AzadehMR, ShamsS, Parvaresh-MasoudM.Evaluation of bacterial contamination on prehospital ambulances before and after disinfection. Prehosp Disaster Med. 2018;33(6):602–606.

scholarly journals What Kind Of Capitalism For Azerbaijan? A Comparative Analysis From Economic View

2011 ◽  
Vol 10 (6) ◽  
pp. 57
Author(s):  
Ayhan Guney ◽  
Ilkin M. Sabiroglu ◽  
Cihan Bulut
Keyword(s):  
Market Economy ◽  
Capital Accumulation ◽  
Agricultural Sector ◽  
Free Market ◽  
Open Market ◽  
Before And After ◽  
Major Factors ◽  
The Impact ◽  
Historical Periods

Every country has experienced various capital accumulation processes due to their own specific conditions. Differences in these conditions have ensured various countries to enter the process of economic development in dissimilar historical periods. Due to the central characteristics of the previous command economic system and the impact of powerful heritage from the USSR on the bureaucratic administration, Azerbaijan is still having difficulties in transitioning to a free-market economy. Today, the transition to an open market economy for Azerbaijan is not completely realized. This research attempts to investigate the major factors of the formation process of the capitalist economic structure in Azerbaijan before and after the demise of the Soviet Union.It focused on the fundamental role of oil and relatively, the agricultural sector and also looked into the types of capitalism the country is currently experiencing based upon certain criteria and statistical indicators.

SMODERP — A Simulation Model of Overland Flow and Erosion Processes

Soil Erosion ◽  
2000 ◽  
pp. 135-161 ◽  
Author(s):  
T. Dostál ◽  
J. Váška ◽  
K. Vrána
Keyword(s):  
Simulation Model ◽  
Overland Flow ◽  
Erosion Processes

scholarly journals HYDROLOGICAL RESPONSES OF A WATERSHED TO VEGETATION CHANGES IN A TROPICAL SEMIARID REGION

2018 ◽  
Vol 31 (1) ◽  
pp. 161-170 ◽  
Author(s):  
EUNICE MAIA DE ANDRADE ◽  
RAFAEL DO NASCIMENTO RODRIGUES ◽  
HELBA ARAÚJO DE QUEIROZ PALÁCIO ◽  
JOSÉ BANDEIRA BRASIL ◽  
JACQUES CARVALHO RIBEIRO FILHO
Keyword(s):  
Daily Precipitation ◽  
Semiarid Region ◽  
Rainfall Characteristics ◽  
Hydrological Responses ◽  
Precipitation Water ◽  
Before And After ◽  
Student’S T ◽  
Moisture Conditions ◽  
Precipitation Events ◽  
Student’S T Test

ABSTRACT The objective of this work was to assess the effect of vegetation on the runoff coefficients of a Caatinga dry tropical forest before and after thinning. Thus, an experiment was conducted with evaluations in three hydrological years (2008, 2011 and 2013) in Iguatu, State of Ceará, Brazil. In 2008, the vegetation consisted of a 30-year regenerating Caatinga forest. The vegetation was subjected to thinning in 2009, 2011 and 2013, removing trees with less than 10-cm diameter at breast height. Hydrological responses were evaluated as a function of daily precipitation water depths, based on cumulative frequency distribution, by dividing precipitation events into three classes (CP) (CP≤30, 30<CP≤50 and CP>50 mm). Significant differences between runoff coefficients before and after vegetation thinning were assessed through the Student's t-test (p<0.01). Before thinning (2008), CP≤30 mm showed the highest runoff coefficient, differing statistically (p<0.01) from the other years. The results of precipitation events of great magnitude (CP>50 mm) indicate that the runoff is greatly dependent on rainfall characteristics and soil moisture conditions. The greater development of herbaceous vegetation due to thinning reduced the surface runoff.

Changes in Soil Physical Properties due to Cable Yarding and their Hydrologic Implications

1992 ◽  
Vol 7 (2) ◽  
pp. 36-39 ◽  
Author(s):  
Michael D. Purser ◽  
Terrance W. Cundy
Keyword(s):  
Overland Flow ◽  
Water Storage ◽  
Soil Physical Properties ◽  
Cascade Mountains ◽  
Before And After ◽  
Commercial Logging ◽  
Cable Yarding ◽  
Dominant Process ◽  
Ks Values ◽  
Changes In Soil Properties

Abstract This study was performed to measure changes in soil properties due to cable yarding and to estimate the resulting changes in hydrologic response. Soils were sampled before and after a commercial logging operation in the northern Cascade Mountains of Washington. The samples were analyzed for saturated hydraulic conductivity (Ks), moisture release characteristics, and bulk density (BD). Postlogging Ks values ranged from 1.08 to 497 cm/h and were significantly less than prelogging values, which ranged from 10.8 to 623 cm/h. Postlogging bulk densities ranged from 0.34 to 1.13 g/cm³ and were significantly greater than prelogging values, which ranged from 0.10 to 0.95 g/cm³. Because of the high Ks values it was concluded that Horton overland flow is not a dominant process even after disturbance. A 32.7% reduction in available water storage was found due to decreases in noncapillary porosity and surface horizon thickness. From this, increases in saturation overland flow and/or subsurface flow are predicted on skid trails. Overall impacts on the cutting unit however are considered small. West. J. Appl. For. 7(2):36-39.

scholarly journals Using UAV Multispectral Images for Classification of Forest Burn Severity—A Case Study of the 2019 Gangneung Forest Fire

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 1025 ◽  
Author(s):  
Jung-il Shin ◽  
Won-woo Seo ◽  
Taejung Kim ◽  
Joowon Park ◽  
Choong-shik Woo
Keyword(s):  
Forest Fire ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Accurate Method ◽  
Burn Severity ◽  
Spectral Angle Mapper ◽  
Before And After ◽  
Uav Images ◽  
Uav Image

Unmanned aerial vehicle (UAV)-based remote sensing has limitations in acquiring images before a forest fire, although burn severity can be analyzed by comparing images before and after a fire. Determining the burned surface area is a challenging class in the analysis of burn area severity because it looks unburned in images from aircraft or satellites. This study analyzes the availability of multispectral UAV images that can be used to classify burn severity, including the burned surface class. RedEdge multispectral UAV image was acquired after a forest fire, which was then processed into a mosaic reflectance image. Hundreds of samples were collected for each burn severity class, and they were used as training and validation samples for classification. Maximum likelihood (MLH), spectral angle mapper (SAM), and thresholding of a normalized difference vegetation index (NDVI) were used as classifiers. In the results, all classifiers showed high overall accuracy. The classifiers also showed high accuracy for classification of the burned surface, even though there was some confusion among spectrally similar classes, unburned pine, and unburned deciduous. Therefore, multispectral UAV images can be used to analyze burn severity after a forest fire. Additionally, NDVI thresholding can also be an easy and accurate method, although thresholds should be generalized in the future.

Soil erosion and runoff in improved pastures of the Clwydian Range, North Wales

1998 ◽  
Vol 130 (4) ◽  
pp. 473-488 ◽  
Author(s):  
P. A. JAMES ◽  
R. W. ALEXANDER
Keyword(s):  
Particle Size ◽  
Soil Erosion ◽  
Overland Flow ◽  
Ground Cover ◽  
Erosion Processes ◽  
North Wales

Studies of soil erosion in upland and marginal upland Britain are reviewed. Processes affecting soil erosion and runoff are described in marginal upland improved pastures of differing age in the Clwydian Hills, including one which was cultivated twice during the study period. A Gerlach-type trough was designed for trapping sediment and filtered runoff from bounded plots and for operating under grazing. Erosion and runoff amounts are interpreted in the light of ground cover, rainfall amounts and intensity, the action of grazing stock and other animals, and other influences. The chief erosion processes are the action of animals and surface wash by unconcentrated overland flow; no rilling occurred. The significance of particle size of eroded sediment is discussed.

Remote Sensing of Forest Fire Severity and Vegetation Recovery

1996 ◽  
Vol 6 (3) ◽  
pp. 125 ◽  
Author(s):  
JD White ◽  
KC Ryan ◽  
CC Key ◽  
SW Running
Keyword(s):  
Satellite Data ◽  
Fire Severity ◽  
Canopy Cover ◽  
Burn Severity ◽  
Vegetation Recovery ◽  
Electromagnetic Spectrum ◽  
Vegetation Types ◽  
Burned Areas ◽  
Before And After ◽  
Forested Areas

Burned forested areas have patterns of varying burn severity as a consequence of various topographic, vegetation, and meteorological factors. These patterns are detected and mapped using satellite data. Other ecological information can be abstracted from satellite data regarding rates of recovery of vegetation foliage and variation of burn severity on different vegetation types. Middle infrared wavelengths are useful for burn severity mapping because the land cover changes associated with burning increase reflectance in this part of the electromagnetic spectrum. Simple stratification of Landsat Thematic Mapper data define varying classes of burn severity because of changes in canopy cover, biomass removal, and soil chemical composition. Reasonable maps of burn severity are produced when the class limits of burn severity reflectance are applied to the entire satellite data. Changes in satellite reflectance over multiple years reveal the dynamics of vegetation and fire severity as low burn areas have lower changes in reflectance relative to high burn areas. This results as a consequence of how much the site was altered due to the burn and how much space is available for vegetation recovery. Analysis of change in reflectance across steppe, riparian, and forested vegetation types indicate that fires potentially increase biomass in steppe areas, while riparian and forested areas are slower to regrow to pre-fire conditions. This satellite-based technology is useful for mapping severely burned areas by exploring the ecological manifestations before and after fire.

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