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Pesticides are used worldwide to support food security for the growing world population. In Israel thousands of tons of pesticides are applied every year and find their way to the entire catchment: soil, surface water, interflow and groundwater. In addition, the treated waste water applied for irrigation convey pharmaceuticals that are distributed in the catchments as well. Previous studies focused one or a few pollutants, which limit the scope of the chemical features on the pollutants fate. Other research focused a certain flowpaths: the stream and tributaries, or groundwater pollutants. This study provides a wide scope of the all 3 main flowpaths (surface water, interflow, groundwater) and the fate of over 70 pesticides in the field scale, including time series in short temporal resolution for groundwater and interflow.The study took place during irrigation (Apr 2021) and during winter 2022, focusing two winter storms (Jan 2022). The study fields border the Kishon, the 2nd largest coastal stream in Israel. Both fields have subsurface drainage system to address high water level and bad drainage soils. The subsurface drainage system provides direct approach to the subsurface water. Water collected from the pipe outlet of the system represent subsurface, but also from manholes, which are the approach to the subsurface system. Groundwater was collected from piezometers to deep and shallow aquifers in both fields, according to accepted protocol for ground water sampling, utilizing a metal bailor. Surface water was collected from field surface, applying RCU-Runoff Collector Units and also from secondary and primary surface drainage trenched in the field. All water were collected in glass bottles, and were analyzed by LC/MS.In this study the spatial distribution in the field scale was demonstrated, including the vertical direction. Samples that were collected from surface water, interflow and groundwater show the dominant flowpath of each compound, where the chemical characteristics were critical to obtain the compound pathway. For example, imidacloprid was applied only a few weeks before the storm and found in high concentration in surface water. Interflow water collected from subsurface drainage system show imidacloprid concentrations which are order of magnitude lower for the entire winter. On the other hand, diflufenican was applied more than two years ago was found in high concentration in surface water, as a result of low degradability and low mobility, yet subsurface concentrations were negligible. Both compounds were in high concentration near the application area (onion section of the field). Time series (interflow, groundwater) were key data, where taken before, during and after water enter soil column during irrigation or a rain event. All data clustering analysis, showing pairs of compounds vs each other was operated. A clear clustering, in most cases, fit the spatial distribution establishing 4 groups: 1. surface runoff from field and all trenches 2. Subsurface water pipe (and manholes in most cases) 3. Groundwater 4. StreamThis research provides a large data base, including temporal and spatial point of view which are innovative and provide a comprehensive scope for field-scale processes.

Rock fragments in soil and on the soil surface affect key soil hydrological processes, including water repellency, thermal properties physical degradation, erosion, and productivity. The severe wildfire at Mt. Carmel, Israel, in 2010, caused massive destruction of carbonate rocks. The thermal shock caused extreme exfoliation, producing large and flat clasts, affecting rocks to a depth of up to 20 cm. A decade after the fire, most flakes and spalls disappeared from the rock outcrops and adjacent soils. From these observations, this study pursued two objectives: (a) to monitor and analyze the spatio-temporal distribution of the disintegrated flakes 10 years after the fire and (b) to test the hypothesis that fires contribute to increased soil stoniness via physical and chemical flake erosion. This research showed that after a decade, most of the spalled surface on the burned outcrops was lost, broken down and pulverized, exposing new rock surfaces to atmospheric and weathering processes. The most prominent effects were changes in surface stoniness on the rendzina soils over the chalks, while there was less impact on the dolomite and limestone samples. The stoniness of the non-burned chalk was 23-39% and increased significantly to 69-86% in the burned area. Chalk erosion produced large (>16 mm, median 8-16 mm) and abundant gravel, suggesting fragmentation of large spalls, and particles that lost their bladed shapes becoming oblate and equant. While earlier works suggested that increasing rock fragment cover is often associated with the removal of fine particles, our results showed a substantial increase in rock fragments due to fire-induced exfoliation of rock surfaces, leading to long-term changes in soil properties. We therefore propose that the size, shape, and spatial distribution of rock fragments should be considered when examining the effects of rock fragments on hydrological and geomorphological processes or on post-fire soil rehabilitation.

The Eastern Alps are an important tourist destination and attract many visitors every year for their scenic beauty, sports attractions and rich cultural heritage. Tourism is an important source of income and contributes to the revival or maintenance of local traditions. However, tourism also has potential negative impacts on the regions, for example Austria's largest forest fire in Hirschwang near Reichenau an der Rax (district of Neunkirchen) in the period 25.10.2021 to 6.11.2021 was anthropogenically triggered by tourists.In addition to the anthropogenic factors, the increase in extreme weather events caused by climate change and its scale dependent variations are a major challenge in the preparation of wildfire risk maps.Wildfires in steep Alpine valleys behave differently than those on flat or moderate inclined slopes. The present work describes a wildfire that occurred in August 2018 in a famous world-heritage site in Austria (Melzner et al. 2019), which was presumably initiated by a carelessly discarded cigarette or the reflection of a broken glass bottle at the foot of the rockwall. Indicators of fire severity and rockfall occurrence during and after the fire are described.The vertical rockwalls, the anabatic winds and patchy vegetation pattern, caused an upward jumping of the fire resulting in a spotty fire pattern. This most probably resulted in spatially varying fire intensities, and consequently highly heterogenic changes in soil and rockmass structure. The wildfire clearly showed that wildfires can have a significant impact on ecosystems and pose a high risk to settlements in the Alpine area. The rockfall hazard and risk assessment conducted in 2014 (Melzner 2015) enabled a fast decision making as part of an emergency response during and after the wildfire catastrophe in terms of identification of possibly endangered houses and planning of preliminary rockfall preventive measures.

Non-point pollutants, such as fertilizers and pesticides, are transported in water and travel via complex hydrologic flowpaths, with each field being a diffuse source of agrochemicals. Although pollutant transport in tile drains has been investigated widely, most studies occurred in temperate zones, with insufficient focus on leaching timing. We investigate the leachate timing and specific pathways from the field to the stream, to better understand the unique transport dynamics in Eastern Mediterranean climates, in areas with extensive subsurface drainage systems. To improve basin management strategies, this study targets the knowledge gap regarding specific pollutant transport and timing, which results in inefficient policies to reduce water pollution. In our investigation of two crop fields in the Kishon basin, Israel, the systems drain both soil water and high groundwater, providing an opportunity to examine water quality dynamics in multiple pathways. We collected water samples from field runoff, subsurface pipes, and groundwater during summer irrigation and winter storm events. Results show a clear spatial distribution of agrochemicals due to their properties. Higher number of pesticides were found in ponded field water and their concentrations were higher in order of magnitude in compare to tile drainage pipes. We identified pesticides in all samples that had not been applied to the field within the last 1.5 years. Leaching timing was demonstrated with higher pesticide concentration appearing in water collected from drainage pipes during irrigation and pesticides concentration decreasing after irrigation ended. The concentration changes were observed within 12-15 hours after opening or closing irrigation. Tracking the pools, the high concentration in the top soil creates a pesticides reservoir transported with the onset of irrigation and rain. The leaching timing was demonstrated as well by lab results and measuring in-situ EC and pH. After a four-day storm, EC declined drastically, demonstrating the input of relatively low nutrient content water to the high concentrations present in the high water table. Later in the winter, surface runoff in the main draining trench from the field to the stream contained high concentrations of phosphate and sediments and low concentrations of nitrate and chloride, compared to surface runoff in the field. Since nitrate and chloride are highly soluble, the reduced concentration in the draining trench to the stream demonstrates that water percolates downwards through the soil column with solutes rather than propagating with surface runoff, and particulate-bound species and sediments travel via surface runoff to the stream. Demonstrating pollutant transport pathways and timing, we provide a window into the propagation mechanisms of pollutants at a small scale, to support decision making and improve basin management.

In the Eastern Alps no previous research focused on the impact of wildfires on the occurrence of rockfalls. The investigation of wildfires and post-wildfire rockfalls gains new importance with respect to changes in weather extremes and rapid social developments such as population growths and tourism. The present work describes a wildfire that occurred in August 2018 in a famous world-heritage site in Austria. Indicators of fire severity and rockfall occurrence during and after the fire are described.

Wildfires occurring near and within cities are a potential threat to the population's life and health and can cause significant economic damage by destroying infrastructure and private property. Due to the relatively small area of these wildlands, the accuracy of fire risk-assessment plays a significant role in fire management. Introducing the experience of real events can improve accuracy. But this approach is limited by a lack of knowledge of pre-fire conditions, mainly vegetation characteristics as related to their definition as a fuel parameter because of their high temporal variation. To solve this problem, an Artificial Neural Network (ANN) was designed to reconstruct the spectral characteristics of the vegetation just before the fire with spatial resolution 0.5–2 m from the Landsat image. To test the effectiveness of the proposed methods, the approach has been examined on urban vegetation sites and applied to restore spectral information of the actual vegetation patch before it was burned in 2016 in Haifa, Israel. The results show that the reconstructed RGB image allows for mapping the location of green vegetation with high spatial accuracy. However, spectral data in the visible range have some limitations when it comes to identifying differences between soil and dry plants. The reconstructed image was used to sharp the original data from Landsat. Normalized Difference Vegetation Index maps were produced from the resulting high-resolution multispectral image. The output maps allow to determine the location of vegetation and estimate the level of its dryness on the urban wildland landscape. The proposed method aims to estimate vegetation dryness and, as a result, identify the fuel characteristics at the time of the fire. It has the potential of using for evaluation and improve the weights of the input parameters for the fire-risk assessment and fire-behavior modeling on a specific area.

The incidence of large rain events in Mediterranean ecosystems vary among years. Summer aridity is interpreted as a resetting event, eliminating previous soil‐moisture dynamics. The dynamics of soil moisture and retention are critical to tree survival, particularly in dry regions. This study examines the long‐term soil water content (θV) dynamics in two distinct locations within the forest, under the canopy and forest clearing, within two diverse oak forests: subhumid mixed oak forests (MG) and semiarid monospecific oak woodlands (YE). Plots were established at small‐scale catchments and soil water contents were measured during 2010–2013, at three depths in the two different locations. Cumulative rainfall was used as an independent proxy for θV analysis. A novel bell‐bilogistic mathematical model of wetting, saturation, and drying arms was developed. We aimed to study the θV distribution differences between soil profiles giving the large climatic gradient between the two forested sub basins, the differences in vegetation traits along with soil attributes. We further aimed at determining the role of an individual tree in regulating soil‐moisture dynamics. We hypothesized the occurrence of distinct responses between sites in all soil‐moisture indices with higher θV at the wetter site. We tested the hypothesis that seasonal cumulative rainfall dictates the variations in soil‐moisture regimes throughout contiguous years. Annual rainfall was higher than long‐term average throughout the study. Soil profiles under the canopies at both sites were consistently wetter. Infiltration and depletion constants were higher at MG whereas maximum soil moisture was higher at YE. Homogenous recharge patterns were seen at MG although YE evinced more variation. Oaks had no effect on recharge at MG compared with the forest clearing. Soil properties primarily affected the wetting arm whereas vegetation composition regulated the drying arm. Mixed‐stands characterized by ever‐green and deciduous species may maintain favourable soil‐moisture conditions, in comparison with other mixed stand morphologies. The increasing role of slacking forces in infiltration process may alter the interaction between trees and herbaceous vegetation.

Fire is a natural and important part of the disturbance regime that has shaped the Mediterranean landscape. Once established in the ecosystem, fires affected vegetation structure and soil-forming dynamics and became a key factor in creating the current mosaic pattern of the Mediterranean. Fires increase runoff and soil erosion by removing vegetation, changing soil properties and providing layers of sediment and ash. Given the complexity of the interacting environmental forces and the nature of the fires, fire-induced erosion varies markedly across spatio-temporal scales. Erosion rates at point and plot scales are usually 5–7 orders of magnitude higher than in unburned sites, yet it has been difficult to quantify their magnitudes and importance at larger (basin) scales. The process of ecosystem recovery may last decades, during which the soil is exposed to elevated erosion, considerably higher than its natural formation rates. Numerous knowledge gaps across all spatial scales limit our understanding of the processes contributing to post-fire runoff and erosion; therefore, two directions for future research are suggested: (i) process-based studies to understand the dynamics and interacting factors controlling surface runoff and erosion, particularly in relation to fire regime; (ii) a landscape-scale approach to quantify erosion at hillslope and basin scales.

Climate change, increased frequency of natural disasters and their anomaly in the modern world demand review existing knowledge about environment and approaches for its management. In recent decades, one of the phenomena that humanity met with is urban wildfires. Experience has shown that existing approaches from forest fire management are not effective in a built-up environment. In practice, studying this phenomenon is limited due to lack of empirical knowledge.To bridge this knowledge gap, the fire dynamic patterns in an urban area was reconstructed based on fire service data on the example of wildfire in Haifa (Israel) in November 2016. The results of reconstruction show that unlike forest fires, where fuel is almost unlimited around the ignition point, urban areas are sensitive to wildfire because of 'fire connectivity' through vegetation: fire moves from one green patch to another, bypassing nonflammable structures.Although the role of urban vegetation in the spread of fires is obvious, it is difficult to define a suitable term in case of fire management. Today, cities and vegetation are studied together in the urban planning and ecosystem services and have different definitions, depends on study propose: ‘Urban Green Spaces’, ‘Green Infrastructure’, ‘Urban Forestry’, etc. The closest term in fire management for vegetation interaction with structures is ‘Wildland Urban Interface’ (WUI). However, WUI considers vegetation surrounding the city and excludes urban green spaces. Since before this time the inner-city vegetation was not considered in the fire management and wasn’t estimated its essential parameters for this case, it does not have an exact term and definition. The reconstructed wildfire allows to analyze and define vegetation in context of fire connectivity.The results show that wildfire spreads in the urban area through ember attacks. Meanwhile, the embers led to ignition only in some patches and only in a few cases the energy amount was enough for new embers emission. Thus, the fire vegetation connectivity in urban areas can be defined by its ability to ignite and reproduce new embers.To support fire management and risk assessment in urban areas, it is important to map vegetation based on its ignitability and potential energy emission. The task is complicated due to the uncertainty of surface fuel (including both litter and human waste). Citywide, detecting and monitoring such patches through field surveys is time-consuming work. To solve this objective by remote sensing technique, we analyzed series of Landsat 8 images for 2015 to identify spectral and temporal features of vegetation related to its flammability. The proposed approach supports estimation and mapping of vegetation connectivity in case of urban wildfire based on its multi-temporal spectral signature.

In November 2016, the urban dry streams (wadis) of the city of Haifa in Northern Israel were on fire. However, it was not just the fire that was threatening urban areas. Post-fire precipitation could turn into urban floods, further aggravating the fire damages. Several months after the fire a considerable restoration effort was initiated to restore the burned areas and mitigate future events. For urban forests the rehabilitation strategy was planned and implemented according to the topographic structure of the burned site and anticipated soil erosion. Accordingly, various post-fire management techniques were used: salvage-logging, afforestation, log erosion barriers and coconut fibre-webs. This study aimed to look at the effects of these methods on soil properties, namely, gravimetrical soil moisture, soil organic matter content, pH, electrical conductivity, hydraulic conductivity and soil water repellency. Results indicate that the control (burned, non-managed) site was the highest in soil moisture, organic matter and electrical conductivity compared to all other sites, however, the existence of ash cover made the response to precipitation unpredictable. The hydraulic conductivity (K) of the black ash (24.1 ± 8.6 mm/h), the white ash (19.0 ± 10.7 mm/h) and the disturbed (mixed) ash (11.7 ± 3.7 mm/h) were significantly higher than the underlying soil (3.3 ± 0.7 mm/h). As a result of these differences in K value, precipitation only infiltrates through the ash layers and then flows along the interface of the ash and the soil, triggering soil erosion. Most of the sites that were salvage logged showed signs of erosion. The log barriers were only effective for downstream areas. The afforestation could help to homogenise the soil, but the vegetation cover would be less dense and stable than after natural reforestation. Furthermore, the coconut fibre webs helped to improve the soil water retention and decreased the direct impact of rainfall.

Severe fires accelerate rock weathering by spalling and exfoliation, creating abundant peels, flakes or spalls. In the following years, these spalls serve as physical traps which accommodate fine particles of dust, ash, organic matter, etc. We searched for traces of ash trapped under the spalls, after four major fires: 1989, 2005, 2010 and 2015 in Israel. Samples were collected beneath the spalls that formed on the rock outcrops, and in the immediate vicinity above and below them. Three laboratory analyses were performed: pH, EC and color. Five mineral/organic compounds were measured across the Mid-Infrared (MIR) spectral region at diffuse reflectance infrared Fourier transform mode: Hydroxylapatite (HAp), charcoal, organic carbon, montmorillonite and kaolinite. Several statistical analyses were performed: MANOVA, PCA and silhouette analysis on K-means clustering. The results show evidence of ash trapped under the spalls formed during the 2005 and 2010 fires, 6 to 11 years after the fires. Charcoal presence is evident, as well as increased amounts of HAp and organic carbon. In the exposed soil above or below the burned rock outcrop, these values are lower. Negligible amounts of ash were measured 27 years after the fire. In the 2015 burned outcrop, large amounts of charcoal were found above and below the outcrop, but not under the spalls. It seems that on the carbonate slopes of Israel and under Mediterranean climate, the time required for spalls to begin functioning as traps is longer than one rainy season, while ash traces are preserved in these traps for a period of two-three decades.

Studies have attempted to disentangle the relationships between urban properties and species richness patterns by studying them within the urban-rural gradient context, the Island Biogeography framework, or the patch-matrix approach. We compared and contrasted these frameworks, to highlight their attributes. We assessed the role of patch properties and matrix characteristics, in light of these approaches, to identify the relative roles of different drivers in dictating urban plant species richness patterns. Vegetation surveys were conducted in 41 open space patches within the city boundaries of Haifa, Israel. Plants were classified into three categories: rare, native and non-native. Patch properties, distance to nearest neighboring patch, distance to city boundary, within patch heterogeneity and percentage of sealed surface buffering the patch were evaluated in relation to species richness. Non-linear regressions indicated that total, rare and native species richness were best explained by a combination of patch area, sealed surface and patch habitat heterogeneity. Non-native species richness was best explained indirectly by the proportion of sealed surface. No clear cut distinctions between the three frameworks were observed. The results point to the existence of non-linear interactive relationships between the drivers and species richness, which depend on patch and urban matrix properties, particularly on degree of urbanization. We conclude that patch-matrix mechanisms interact with the urban-rural gradient approach to determine plant richness patterns in urban landscapes. Additionally, the degree of urbanization is differentially associated with richness patterns, where rare and native species are negatively associated with it, and non-native species are positively associated with urbanization.

Fire is a key factor impacting soil hydrology in many Mediterranean catchments. Soil water repellency (SWR) can stimulate land degradation processes by reducing the affinity of soil and water thereby triggering a reduction in soil fertility and increasing soil and water losses. The effects of two consequent fires (1989 and 2005) on SWR were assessed in the Carmel Mountains, Israel. Fire history, plant recovery and post-fire management (14 treatments) were investigated as determining factors in a time dependent system. In total 210 locations were investigated 9 times from October 2011 to February 2012, which totals 1890 water drop penetration tests that were performed. During each visit to the field (9 times) a soil moisture content was measured for each treatment. SWR was highest in the >. 50. years unburnt plots, where soil under . Pinus halepensis is most hydrophobic. In the most disturbed soils (twice burnt), many sites have a low to absent SWR even if the soil is very dry. The dynamics and fluctuations in SWR differ in magnitude under different plant species. The areas treated with CC (chipping of charred trees) showed a much higher SWR than areas left untreated. From these insights, a conceptual model of the reaction of SWR on multiple fires was developed.

Fires exert many changes on the physical, chemical, morphological, mineralogical, and biological properties of soil that, in turn, affect the soil's hydrology and nutrient flux, modifying its ability to support vegetation and resist erosion. The ash produced by forest fires is a complex mixture composed of organic and inorganic particles with varied properties. This research was conducted to study and characterized ash properties produced at different temperatures and with different soil organic matter combinations. The samples, which included two treatments of soils with underlying mixed leaves and branches composed mainly by Pinus halepensis, Pistacia lentiscus, Cistus salviifolius and typical herbaceous vegetation, versus samples of mixed leaves and branches alone. Both were exposed to 400°C and 600°C heat in a muffle furnace for 2h. The residue ash was generally grayish, consisting of mixed-sized particles that preserved almost none of the original characteristics of the fuel, and was deposited in ash layers with diverse physicochemical and textural properties. The results of this study highlight the differences between all examined samples and strongly support the assumption that ash produced from a complex vegetation-soil system is a new substance with unique structural, textural, and mineralogical properties. Moreover, the ash produced at different temperatures appeared in distinct layering patterns.

Este artículo contiene 16 páginas, 6 figuras, 2 tablas., Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. We investigated the relationships between synoptic atmospheric patterns (i.e. weather types, WTs) and runoff, erosion and sediment yield throughout the Mediterranean basin by analyzing a large database of natural rainfall events at 68 research sites in 9 countries. Principal Component Analysis (PCA) was used to identify spatial relationships of the different WTs including three hydro-sedimentary variables: rainfall, runoff, and sediment yield (SY, used to refer to both soil erosion measured at plot scale and sediment yield registered at catchment scale). The results indicated 4 spatial classes of rainfall and runoff: (a) northern sites dependent on North (N) and North West (NW) flows; (b) eastern sites dependent on E and NE flows; (c) southern sites dependent on S and SE flows; and, finally, (d) western sites dependent on W and SW flows. Conversely, three spatial classes are identified for SY characterized by: (a) N and NE flows in northern sites (b) E flows in eastern sites, and (c) Wand SW flows in western sites. Most of the rainfall, runoff and SY occurred during a small number of daily events, and just a few WTs accounted for large percentages of the total. Our results confirm that characterization by WT improves understanding of the general conditions under which runoff and SY occur, and provides useful information for understanding the spatial variability of runoff, and SY throughout the Mediterranean basin. The approach used here could be useful to aid of the design of regional water management and soil conservation measures., This research was supported by projects funded by the MINECOFEDER: CGL2014-52135-C3-3-R, CGL2014-59946-R, CGL2015-65569- R, CGL2015-64284-C2-2-R, and PCIN-2017-061/AEI. When this manuscript was first submitted Estela Nadal-Romero and Damià Vericat received a “Ramón y Cajal” postdoctoral contract (RYC-2013-14371 and RYC‐2010‐06264, Spanish Ministry of Economy and Competitiveness, MEC). Damià Vericat is now a Serra Húnter Fellow at the University of Lleida. María Fernández-Raga received a “José Castillejo” postdoctoral grant (Spanish Ministry of Education, Culture and Sports). Carla Ferreira was supported by a post-doctoral research grant from the Portuguese Science and Technology Foundation (SFRH/ BPD/120093/2016). Mariano Moreno-de las Heras received a Juan de la Cierva postdoctoral contract (IJCI-2015-26463) from the MEC. José Andrés López-Tarazón received a Vicenç Mut postdoctoral fellowship from the Autonomous Balearic Government (CAIB PD/038/2016). José Andrés López-Tarazón and Ramon Batalla also acknowledge the Secretariat for Universities and Research of the Department of the Economy and Knowledge of the Autonomous Government of Catalonia for supporting the Consolidated Research Group 2014 SGR 645 (RIUSFluvial Dynamics Research Group), and the CERCA Programme. This paper has benefited from the Lab and Field Data Pool created within the framework of the COST action CONNECTEUR (ES1306).

The severe wildfire at Mt. Carmel, Israel, in 2010, caused massive destruction of carbonate rocks. The thermal shock caused extreme exfoliation, producing large and flat clasts, affecting rocks to a depth of up to 20 cm. A decade after the fire, most flakes and spalls disappeared from the rock outcrops and adjacent soils. From these observations, this study pursued two objectives: (a) to monitor and analyze the spatio-temporal distribution of the disintegrated flakes 10 years after the fire and (b) to test the hypothesis that fires contribute to increased soil stoniness via physical and chemical flake erosion. The studied area included five lithostratigraphic units composed of chalk, limestone, and dolomite. The Schmidt Hammer test showed that after a decade, most of the spalled surface on the burned outcrops was lost, exposing new rock surfaces to atmospheric and weathering processes. The spalls and flakes were broken down and pulverized. The most prominent effects were changes in surface stoniness on the rendzina soils over the chalks, while there was less impact on the dolomite and limestone samples. The stoniness of the non-burned chalk was 23–39% and increased significantly to 69–86% in the burned area. Chalk erosion produced large (>16 mm, median 8–16 mm) and abundant gravel, suggesting fragmentation of large spalls, and particles that lost their bladed shapes becoming oblate and equant. While earlier works suggested that increasing rock fragment cover is often associated with the removal of fine particles, our results showed a substantial increase in rock fragments due to fire-induced exfoliation of rock surfaces, leading to long-term changes in soil properties. We therefore propose that the size, shape, and spatial distribution of rock fragments should be considered when examining the effects of rock fragments on hydrological and geomorphological processes or on post-fire soil rehabilitation.

The definition of urban soil is descriptive, a description of a state, not a taxonomic classification. There are no physical or chemical property lists for it as for general soils’ definition. “Urban soil” is a generic term and can be interpreted in many ways, but it refers to soils affected by urbanization. Urban soils supply environmental services and support the urban vegetation communities, despite being essentially different from natural soils. The main goals of this paper were to characterize urban soils in open green undisturbed patches and find a feature that will identify urban soils, not directly affected by urbanization process, like construction, residential, and transportation development. Seventy soil samples were collected from Mount Carmel National Park, city of Haifa’s remnant patches and disturbed sites. The samples were taken from horizon A, after the coarse organic particles or trash residues were removed. Two non-distractive spectral methods across visible and near, shortwave, and mid-infrared (VNIR-SWIR-MIR) spectral regions were used to characterize the soil minerology and total carbon content (0.35–25 μm) and analyzed by previously published top-down spectral unmixing method. The urban soils from all the city sites were found to be a combination of anthropogenic residue, contaminants alien like actinolite and chrysotile traces, local clay, and silicate minerals, while the park’s soils contained none. Furthermore, the average total carbon content found in urban soils was significantly lower than the amount found in the park’s samples. The results of the spectroscopy and analytical chemical analysis could not set apart the urban soils; all samples contained materials from anthropogenic origin. Yet, urban soil samples and park soil samples had different spectra features, which set the two soils significantly apart. The spectra of urban soil samples contain high absorption features at the VNIR and very few and much less information at the MIR wavelength. This fundamental difference can define urban-affected soils. The spectral feature found in this study may be useful for creating a non-destructive method to trace the urbanization changes in rapid acquisition of soil information at quantitative and qualitative levels.

Post-fire environmental footprint is expected at varying scales in space and in time and demands development of multi-scale monitoring approaches. In this paper, a spatially and temporally explicit multi-scale model that reveals the physical and morphological indicators affecting hillslope susceptibility at varying scales, is explained and demonstrated. The qualitative and quantitative suitability classification procedures are adapted to translate the large-scale space-borne data supplied by satellite systems (Landsat OLS8 and Sentinel 2 and 3) to local scale produced by a regional airborne survey performed by unmanned aerial vehicle (UAV). At the smallest spatial and temporal resolution, a daily airborne imagery collection by UAV is linked to micro-topography model, using statistical and mathematical approaches.

The December 2010 forest fire on Mount Carmel – the largest recorded in Israel – burned about 2500 ha of Mediterranean forest. We documented the immediate and short-term changes of the vegetation following this fire. Relative vegetation cover and plant species richness were sampled in five sites in spring 2009 and 2010, prior to the fire, and were re-sampled in 2011 and 2012. The number of recurrent fires (between 0 and 3) and time intervals between fires were documented for each site. We observed a strong decrease in total vegetation cover, associated with reduction of relative cover of woody vegetation. In the second year after the fire, shrubs and dwarf shrubs became dominant at all sites. Time intervals between fires played an important role in determining the extent of regeneration of the vegetation cover and plant species richness. Plant species richness immediately decreased after the fire in sites with a short fire interval, while in sites with a long fire interval, plant species richness increased. Relative plant cover was associated with the time from the last previous fire, and this association differed among different plant groups. These results suggest that vegetation and plant community regeneration after recurrent fires is accelerated when time intervals between fires are longer, whereas high fire frequency may suppress vegetation regeneration. Based on the results, we propose that forest regeneration after recurrent fires depends largely on time from the previous fire, rather than on the number of previous fires. Copyright © 2015 John Wiley & Sons, Ltd.

Article history:Received 25 July 2013Received in revised form 29 April 2014Accepted 20 May 2014Available online 9 June 2014Keywords:Forest firesMediterranean ecosystemsSoil erosionSurface runoffVegetation recovery rates Wildfiresareofprimaryimportanceindeterminingecosystemfunctionandgeomorphologicalprocessinmostoftheforestedlandscapesacrosstheglobe.FollowingafireeventinamaquisforestlocatedattheCarmelmountainrange in northern Israel, we monitored the eco-geomorphic response of the system, in an attempt to explainrunoff andsedimentyield dynamics. Specifically,we assessed growthofvegetation cover, and monitoredrunoffand sediment yield in relation to three controlling factors: fire severity, slope aspect, and slope steepness. Four-teen 10 m 2 plots were constructed in different combinations of aspect, fire severity and steepness, which weremonitored for a period of 24 months.Analysis of vegetation cover indicated that initial growth was faster on the north aspects, but by the end of thestudy period vegetation coverwassimilarto thatofpre-fire levelsonboth aspects. Runoff and soil loss amountsfrom theburntsiteswerecommonly significantly higheronthesouth slope,steep gradients and highfiresever-ity,comparedtothecounterpartplots.Temporalanalysisindicatedthatsedimentyieldfromtheplotssignificant-ly decreasedbetween the first and second winter seasons, whereasno statistically significant decrease in runoffwas observed. Applying regression analysis methods we investigated the response of sediment yield to runoff,vegetation cover, soil moisture, rain intensity and precipitation, with respect to each of the controlling factors.In all cases runoff appeared to be a significant variable, as was vegetation cover, with the exception of the mod-erate burnt plots.Wesuggestthatvegetationplaysacomplexroleindeterminingtheresponseofthegeomorphicsystemtowild-fireperturbations.Whilethemerepresenceofvegetationissufficienttoreducesoilloss,itisnotsufficienttosig-nificantly affect runoff, most likely due to the different architecture of the newly regenerated vegetation.Additionally, vegetation seems to be an important factor in the harsher environments where more intensivesoilmovementsoccur,asthe conditionaleffect of vegetation ismorepronounced,and its contribution tothere-duction of soil movements is higher.© 2014 Published by Elsevier B.V.

Wildfire events and anthropogenic activities such as agriculture and livestock grazing may denude the landscape from vegetation cover, resulting in systems prone to soil loss and degradation. Soil dynamics is an intricate process balanced between pedogenesis, which is a relatively slow process, and erosion which depends on many inert (e.g., soil texture, slope, precipitation, and wind) and biological factors such as vegetation properties, grazing intensity, and human disturbance. We develop here a theoretical model of the global dynamics of the interactions between vegetation and soil. Assuming a double feedback between them—plants control erosion, and soil availability facilitates plants growth—a system of nonlinear differential equations is derived, and the outcomes are investigated. The range of realistic parameter values were taken from the literature. Complex properties emerge from this model. For some ranges of parameter values, the model predicts one of two types of steady states—full recovery of vegetation cover or a degraded barren system. For another range of parameter values, bistability appears. We identify the parameter combinations which determine the qualitative behavior of the system and the threshold values beyond which the system becomes bistable. The model predicts that certain ecosystems are highly stable. Others might be bistable transitioning between these two states through perturbations. Therefore, the possibly of hysteresis as parameters vary arises, as well as the ability of the system to shift between steady states, possibly leading to sudden and dramatic changes.

The effects of urban sprawl, at the expense of green natural areas, and the increasing anthropogenic pressure on these areas, lead to significant changes in land cover composition and structure. One of the threats and hazardous aspects of the urban sprawl is the disposal of construction site waste (CW) at the cities’ fringes and by the roadsides. The analysis of vegetation community structure over space and time in such areas may contribute to the understanding of community dynamics at the urban fringe following modern human intervention. Therefore, the purpose of this study was to characterize the composition and structure of vegetation communities in construction waste and rubble areas at the city of Haifa’s fringe. A control undisturbed site, and sites that were disturbed 20, 40 and 60 years prior to the study were selected and studied. The results indicate that superficially there is no difference among the communities. A closer analysis, however, reveals that there is a significant segregation in species assembly between the control and the damaged sites, and that this difference becomes more significant as time passes. Initially, recently disturbed sites were characterized by a higher abundance of ruderal species, where mean number of ruderal species was 1.75/sampling quadrate, compared to 0.08 species/sampling quadrate. As time passes, the number of exotic species increased from 0.09 species/sampling quadrate at the 20 year disturbed site to 1.02 at the 60 year sites. Additionally, cover of climber species in the sites significantly increased with time, and other local life form groups declined in richness. Further, we have found that the impact of the CW is spreading beyond the area that it was found and into the open and undeveloped area that surround the city.

The increasing number of fires, fire size, and decreasing fire recurrence intervals are major environmental factors in Mediterranean-type ecosystems, and are known to affect Aleppo pine (Pinus halepensis) forests. The fact that in the Mediterranean basin most fires are man-made increases the danger of fires recurring at short intervals. P. halepensis is a lowland Mediterranean species with a disjunct east-Mediterranean population in Israel and Jordan, with the Mount Carmel population as one of the few native pine forests in Israel. Here we assess the effect of recurrent fires on the regeneration and spatial distribution of P. halepensis, as reflected by the number of trees at 18 sites, according to the number of previous fires and the time elapsed since the last fire. At each site, 100 × 1 m−2 squares were randomly placed to record numbers of trees. Results indicate that in most cases the number of pines per unit area is inversely proportional to the number of fires. For example, tree density in sites that were last burnt during the spring of 2005, varied between 1.2 trees m−2 (single-fire), and 0.25 and 0.39 trees m−2 in two- and three-fire sites, respectively, while in the unburnt control sites pine density was 0.46 trees m−2. The effect of recurrent fires, however, was particularly evident when the time interval between two successive fires was shorter than 20 years – the time needed for P. halepensis trees to mature and produce an adequate canopy seed bank. Apparently, not only the number of fires, but also the fire season has a major effect on regeneration dynamics. Although frequent recurrent fires reduce the number of pines at the site, their total elimination from any site never occurred, demonstrating the resilience of this species and its accommodation to short-interval recurrent fires. These results are crucial for establishing post-fire management programmes in fire-prone Mediterranean ecosystems.

On 24 November 2016, extreme hot and dry weather led to more than 1000 fires in Israel. One of the largest fires (120ha) occurred in the city of Haifa. The fire began on the slopes of the north-eastern part of the wildland–urban interface (WUI) and spread into the city, moving westward owing to strong wind gusts. Although private houses in open lands and villages in Israel have previously been affected by fires, this was the first ‘urban fire’ in Israel. In order to determine the best management strategy for the various types of burned areas, an ‘identity card’ was prepared for each area including main vegetation species and other points of interest. For urban forest areas, rehabilitation was planned according to topographic structure and anticipated soil erosion. In each reclaimed area, terraces were constructed using burned logs or local stones and inhibitors to mitigate soil erosion. After restoration, each urban forest underwent planting and renewal according to its geographic properties and location.

During 2–5 December 2010, an area of 2500ha in the Carmel forests was consumed by a severe wildfire, causing soil erosion from the exposed slopes. Whereas most studies show that post-fire erosion rates tend to decline after the second year, in this case, we aim to address the ongoing consequences that different management practices had on soil erosion 3 and 4 years after a fire. Three management operations were applied: (a) preservation management (PM) – mulching wood chips on the burned area; (b) tree-clearing management (TCM) – burned trees were cut and removed; and (c) skid-trail formation (ST) – provisional pathways were formed while trees were dragged outside. Consequently, the objectives of the study were: (1) to monitor the effects of these post-fire practices 3 and 4 years after fire; and (2) to characterise the physical features of the eroded soil. The sediments were collected after every effective rain event over two rainy seasons (2013–14, 2014–15). TCM and ST practices resulted in significantly elevated soil-erosion yields compared to PM. The sediments following PM had a high percentage of fine material. Furthermore, PM had an evident positive effect on the soil, whereas all other practices inhibited vegetation renewal and system rehabilitation.

Soil water repellency (WR) is one of the properties most affected by combustion during a forest fire. Different factors such as temperatures reached, type and amount of fuel, affect the changes observed in this property. Measurements of water repellency can be made directly in the field or in soil samples under laboratory conditions. On the other hand, previous laboratory findings have demonstrated that some soil properties can be key factors controlling the development of WR by burning. One of the objectives of this research was to confirm findings from laboratory-burning under wildfire field conditions. In summer 2008 WR was assessed in five areas recently affected by fires in Mt. Carmel (NW Israel) and Alicante (SE Spain). Study sites are quite similar with regard to vegetation and climate, the main difference between sites being the type of soil and therefore soil characteristics. In each one of the study areas WR was tested beneath Pinus halepensis in both burned and unburned (control) adjacent sites. WR test were conducted under field conditions in triplicate using the water drop penetration time (WDPT) test in the top of the A horizon. A total of 300 field measurements were done. Soil samples from the first 0–2.5 cm depth were also taken from the same microsites where WR was assessed for laboratory measurements. Estimations of temperatures reached in burned samples were also made using NIR models developed under laboratory conditions. In general terms, without distinguishing between areas, fire increased the frequency of occurrence of WR in affected soils. However, the magnitude of this effect was quite different depending on the studied area. Three of the study sites, showed very low WR values both in burned and unburned areas. The results are in agreement with those from our previous laboratory experiments (Arcenegui et al., 2007; Mataix-Solera et al., 2008), and are not explained as a consequence of different temperatures reached in the soils. Organic matter and clay content together with the mineralogy of the clay fraction seem to be responsible for the different soil behaviour. Although there is a correlation between field and laboratory WR data (R 2 = 0.549; P

Fire is a common disturbance in Mediterranean ecosystems, and can have a destructive, influential, and even essential, effect on vegetation and wildlife. In recent decades there has been a general increase in the number of fires in the Mediterranean Basin, including in Mount Carmel, Israel. The effects of recurrent forest fires on vegetation cover and species richness were determined in the spring of 2009 and 2010 by field surveys. The results of this study showed that the vegetation cover changes after recurrent forest fires, and can serve as a good indicator of the influence of fire and the resulting ecosystem rehabilitation. The dominant cover in most fire-damaged areas was composed of shrubs and dwarf-shrubs, especially Cistus salviifolius and Calicotome villosa. Tree cover was severely damaged after recurrent fires, and in those areas there was a drastic decrease of the total plant cover. Species richness increased mainly in the first decade after the recurrent fires, and decreased when the forest canopy began to close. Fire recurrence with short intervals (4-6years) between fires may lower the rehabilitated processes of the ecosystem and change its equilibrium.

Wildfires are an important agent in driving ecosystem function by altering vegetation structure and geomorphic processes. In recent decades, the number of wildfires and the total area burned has increased around the world, causing changes to natural regimes. In this study, we compared south- and north-facing slopes, their vegetation structure and dynamics, and the sediment yield generated in areas burned a number of times at the Carmel Mountain ridge in northern Israel. Our underlying hypothesis was that repeated and frequent fires significantly alter eco-geomorphic processes, including prolonged periods of soil erosion and delayed recovery of tree species. We tested whether these phenomenon are characterized by different rates on opposing aspects. To study the long-term changes of the vegetation we analyzed a 21-year (1985–2006) chrono-sequence of satellite images, in areas burned once, twice, or three times. Additionally, we estimated vegetation structure and cover at high resolutions in monitoring plots following a fire in 2005 in areas burned once or twice during the last two decades. To evaluate the long-term dynamics of the system, specific transition probabilities among the vegetation types, as a function of the number of times each site was burned, were used to construct Markov-based transition matrices. Additionally, runoff and sediment have been collected after precipitation events from the plots. The satellite image classifications revealed changes in the composition of tree, shrub, and herbaceous vegetation cover following wildfire events. Satellite image analyses suggest that recurring fires within short-time intervals may significantly alter the long-term structure of the vegetation communities, and may eliminate woody vegetation from the landscape (both trees and shrubs). Consequently, this results in the establishment and dominance of herbaceous vegetation communities. Similar trends were observed in the high-resolution monitoring plots. Sediment yields differed significantly in areas burned twice on south-facing slopes, compared to lower values obtained in areas burned once, or located on north-facing slopes. Thus, we demonstrate that repeated fires may dramatically alter long-term trajectories of Mediterranean-type vegetation communities and ecosystems. This pattern, in turn, may have significant implications for the associated geo-morphological processes, especially runoff and erosion, and should be of particular concern given recent changes of fire regimes.

It has been suggested that during the past several decades, the frequency and the intensity of wildfires have markedly increased in the Mediterranean basin. We came to assess this postulation in the forested region of Mount Carmel, Israel. This region is characterized by Quercus spp. and Pistacia spp. maquis and has been intensely afforested with Pinus spp. stands since the 1920s. We compiled a GIS-based database of the fires recorded in the region since 1983, in addition to archiving data beginning from the 1940s. The data were collected from land stewardship agencies’ archives, fire departments and aerial photographs. Prior to the early 1980s, no systematic documentation of the fires was available, rather just sporadic qualitative documentation of the large forest fires that occurred. Between 1944 and 1982, only 6 large fires were documented, while after that 11 large fires occurred. Analysis indicated that the spatial distribution of the fires does not occur at random, and their locations are significantly closer to roadsides compared to an expected random distribution. The annual number of fires and the areas burned during the last two decades were not correlated with annual precipitation in any manner. Accordingly, we suggest that the increased number of large forest fires during the last decades is associated with the maturation and senescence of the planted forest coupled with increased human activities.

The Mediterranean ecosystem of Mt. Carmel, Israel, is subjected to an increasing number of forest fires of various extents and severities. The impacts of forest fires on runoff and erosion are widely documented and include increased peak flows and soil loss until the return of a vegetation cover. Most studies, however, treat fire as a single event, whereas the present study is aimed at exploring the long-term effects of repeated forest fires on eco-geomorphic processes. The study integrates the results of plot-based, detailed analysis of post-fire runoff and erosion with vegetation recovery analysis, at a temporal-spatial scale which includes the effect of reburning. Our results indicate that forest fires lead to a significant increase in runoff and sediment yields, particularly during the first two years following the disturbance, up to five orders of magnitude higher than from the adjacent unburnt control plots.

Contrary to the popular notion that the advancing frontier of urban development has been swallowing and destroying natural ecosystems we present evidence that the sprawl of cities creates ample open space in peri-urban areas. Traditional view of city–nature dichotomy and clear spatial separation should be substituted by a vision that reflects the complex spatial dynamics of city–rural–natural fabric with extended areas of overlap among them. We present a survey of the relevant research concerning urban and ecological systems spatial dynamics and conclude that nonregular, leapfrogging spatial expansion, characteristic of the majority of the modern western cities, may buffer between urban and intensively cultivated agricultural areas and counter their impacts on natural ecosystems. The wealthy sprawling suburbs provide essential habitats for native species and ensure their survival.

Fire usually induces water repellency (WR) in soils. Reduction in infiltration rates, increase of runoff and erosion are some of the consequences of WR in fire-affected soils. Most forest soils can develop WR by burning; however some previous observations in burned terra rossa soils have shown little changes in WR. Laboratory controlled experiments have been done with samples of terra rossa from 14 different sites. The objectives are to confirm whether the observed is a common behaviour of terra rossa and to explore the factors controlling the wettability of this soil type after burning. Samples from the upper 2.5 cm of terra rossa were collected from 12 forest sites of the Alicante province (Spain), and from 2 sites in the “Mt. Carmel”, Haifa (Israel) with similar environmental conditions. Laboratory burning of samples at 250 °C, 300 °C and 350 °C was performed with and without the addition of litter of Pinus halepensis . The results confirm that all soils have a very low susceptibility to become water repellent by burning. Without the addition of litter, WR was not detected in any soil sample at any temperature of burning. With the addition of litter, WR was present only in six of the soils after some of the heating treatments. Although all soils had enough soil organic matter (SOM) to develop WR by heating, the ratio between SOM and clay content was considerably lower compared to other types of forest soils of the region in which WR has been found after forest fires. This could explain in part the lower susceptibility of terra rossa to become water repellent by burning since, as some authors have indicated, fine-textured soils are less prone to develop soil WR due to their high specific surface area. From mineralogical analysis of the clay fraction we found that the dominant clay types in the studied terra rossa were kaolinite and illite, with the exception of one soil where Ca–montmorillonite content is higher than kaolinite and illite. Ca–montmorillonite was present in only three of the soils. Comparing the soil properties between the group of terra rossa that in no case become water repellent (wettables) with the group that in some cases developed WR (potentially water repellents), some differences were found: the kaolinite content is higher in the wettables group ( P vs kaolinite contents, the kaolinite content being the main factor contributing to this separation. These results are in agreement with those obtained in experiments with clay additions to water repellent soils in order to reduce the WR, and also with some studies which found that kaolinite is one of the most effective clay minerals for this purpose.

The Mediterranean ecosystem of the Carmel Mountain ridge in Israel is subjected to an increasing number of forest fires of various extents and severities due to intense human activities in the region. On 8 April 2005, a low-moderate severity forest fire occurred at the northwestern part of the ridge and burned more than 150 ha of natural vegetation. Soil water repellency (WR) is a property usually modified by the litter and soil organic matter combustion as a consequence of fire, which has implications for the hydrological balance in the affected soils. A field study was conducted with the following objectives: 1) to investigate in situ WR changes at three soil depths as a consequence of the fire, 2) to evaluate the short-term evolution of WR under field conditions, and 3) to study the relationship between pre-fire vegetation type and slope aspect on the persistence of WR in the burned area. Soil WR was measured by the Water Drop Penetration Time (WDPT) test. Measurements were conducted monthly at 31 field sites within the burned area over a period of seven months (April 2005–November 2005), and compared to adjacent unburned areas. Soil WR measurements included more than 3400 WDPT tests at soil surface and at 5 and 10 cm depths. The results indicate that fire induced WR in previously wettable soils exhibited high levels of persistence at the soil surface during the first six weeks after the fire, while at 5 cm depth WR persistence was lower. At 10 cm depth soil was mostly wettable. After six weeks the frequency of WR occurrence diminished at the soil surface and at 5 cm depth. In addition, WR was found to be highly related with the pre-fire vegetation type and with slope aspect.

The Mediterranean ecosystem of Mt. Carmel is subjected to increasing number of forest fires at various extents and severities due to increasing human activities. Accordingly, we tested whether in areas exposed to different fire histories vegetation regeneration is different in north versus south facing slopes, and the potential impact on erosion processes. Using remote sensing techniques we evaluated the Enhanced Vegetation Index (EVI) to monitor vegetation recovery following a single fire and three successive fires, using a series of Landsat images taken between 1985–2002. Following a single fire, vegetation cover reached pre-disturbance values within less than 5 years. Repeated fires caused further reduction of EVI values, especially at south facing slopes (SFS). The effects of three successive fires within 10 years, followed by a three year recovery period, however, are negligible when considering vegetation cover values. This was deduced as north facing slope EVI values returned to pre-disturbance conditions at the end of the 3 years and SFS EVI values to 80% of the pre-disturbance conditions. Our results indicate that Mediterranean eco-geomorphic systems are quite resilient, showing quick response, at least in terms of return to pre-disturbance states of vegetation cover, and hence of soil erosion rates. This is true not only in response to a disturbance caused by a single fire, but also for repetitive fire incidents.

To assess the effect of trees and shrubs on stream structure on different spatial scales, we tested the relationships between their percentage coverage in relation to width, depth and stream slope. This research was conducted during the winter and spring of 2004 at Nahal Oren, Israel, an ephemeral mountainous stream. Our hypothesis, that in the presence of high vegetation cover a deep and narrow stream will form, was based on other studies showing that vegetation stabilizes stream banks. Additionally, we hypothesized that shrub and woody vegetation would have similar effects on stream morphology, and that the spatial scales of their effects will be limited. Four 50 m segments were chosen in the middle part of Nahal Oren, each being characterized by a different vegetative structure. In each segment six cross-sections were preformed 10 m apart as well as a longitudinal profile. Additionally, at three of the cross-section sites vegetation transects were conducted at mid-bank up stream of the cross-sections. Average width/depth ratios at the different sites varied from 5.5 to 9.5 and were not correlated with channel slope. Regression analysis indicated that tree coverage is positively correlated with higher width/depth ratios, at a distance of 1 m above the cross-section. The average shrub coverage at 5 m was negatively correlated with width/depth ratios. We suggest that shrubs and trees may have a similar function in stabilizing banks via the root system, but the above-ground structure of these vegetative types has different effects. Possibly the dense foliage of the shrubs reduces water velocities, thus further increasing bank stability.

Short-term changes in Eastern Mediterranean precipitation affecting flow regime were documented in Nahal Oren, a 35 km 2 ephemeral stream in Mt. Carmel, a 500 m high mountain ridge located at the NW coast of Israel. The rainy winter of the Mediterranean type climate (Csa) in Mt. Carmel is characterized by average annual rainfall of 550 mm at the coastal plain to 750 mm at the highest elevation while the summer is hot and dry. Stream flow generates after accumulated rainfall of 120–150 mm while “large floods”, defined as flows with peak discharge of N 5m 3 s �1 and/or N150,000 m 3 in volume, are generated in response to rainfall of over 100 mm. Hence, large floods in Nahal Oren stream occur not earlier than December. Precipitation and flow data were divided into two sub-periods: 1957–1969 and 1991–2003 and compared to each other. The results indicate a clear increase in the frequency of large floods, their magnitudes and volumes during the second period with no parallel change in the annual precipitation. Similarly, an increase in storm rainfall–runoff ratio from b5% to N15% and a decrease in the threshold rainfall for channel flow by 16–25% were documented. These short-term variations in flooding behavior are explained by the clear decrease in the length of the rainy season and by the resulting significant shortening in the duration of the dry-spells. The increase in the number of large rainfall events and the large floods in each hydrological year together with the increasing number of years with no floods indicate strengthening of their uncertainty of behavior.

Summary A short review of the literature on particle clusters on gravel river beds reveals investigations of both process and form dominated by the intensive study approach, using a restricted geographical sample or evidence from flumes. An alternative, presented here, is extensive sampling – from three climatic zones, several channels in each and at multiple transects at each site. It uses insights provided by a more intensively studied ‘base station’ [Wittenberg, L., Newson, M.D., 2005. Particle clusters in gravel-bed rivers – an experimental morphological approach to bed material transport and stability concepts. Earth Surface Processes and Landforms 30(11), 1351–1368]. Transect surveys were completed in each selected reach to establish flow_depth, bed material size and bed structure. A total of more than 5000 sample points reveals the vital presence of bed material of ≈100 mm D50 for all sub-types of clusters to occur; thereafter, cluster frequency relates directly to the D90, with an improving correlation at D90 > 256 mm. A better integration of data from the diverse hydrological/hydraulic regimes can be achieved by correlating cluster frequency with a sorting index for bed material. Further analysis of hydrological and hydraulic data for all sites is required to develop a dynamic explanation.

The soils found in urban remnant patches may be considered anthropogenic inner urban soils—soils within the administrative boundaries of a municipalities influenced by activities adding artefacts into the soils. Such activities include housing, trading, traffic, production, and disposing. The objective of this study is to determine the scope to which field spectroscopy methods can be used to extend the knowledge of urban soils features and components. The spectroscopy techniques are used broadly for determining specific components or for differentiating between known ones. Moreover, this technique is able to determine low concentration in various phases and to trace hazardous material, and most studies are keen on quantification of those hazardous. In this paper, a top–down analysis for detecting the presence of minerals, organic matter, and pollutants in mixed soil samples is developed and presented. The developed method applies spectral activity (SA) detection in a structured hierarchical approach to quickly and, more importantly, accurately identify dominant spectral features. The developed method is adopted by multiple in-production tools including continuum removal normalization, guided by polynomial generalization, and spectral-likelihood algorithms: orthogonal subspace projection (OSP) and iterative spectral mixture analysis (ISMA).

Mediterranean forests are frequently subject to wildfires, inducing risks of high runoff and loss of nutrient-rich topsoil. The mechanisms influencing these post-fire effects are spatially variable due to differences in vegetation density, litter composition, soil texture and structure, and fire intensity, and therefore difficult to separate. The characteristics of the soil surface in the immediate post-fire period are of critical importance to the hydrological response and erosion susceptibility of the burnt hillslope and catchment. In laboratory experiments, uniform soil, controlled temperature and rain regimes were used to create a controlled environment to isolate the impact of certain influencing parameters. In this study, for a Rendzina soil, we investigated the post-fire impacts of laboratory fire and two successive rainfall (rotating disktype) simulation experiments to evaluate short-term effects of fire on soil hydrological and erodibility parameters by examining (i) soil water repellency (WR) levels and distribution, (ii) surface cover features, and (iii) infiltration, runoff and erosion responses to simulated rain on control (bare and pineneedle covered) and burnt (with and without ash cover) samples. Fire-induced surface WR tested in the laboratory by grid-wise Water Drop Penetration Time tests (WDPT), revealed moderate WR, which decreased for all treatments after rainfall. The response to rain (33 mmh-1) differed for the two simulation runs. The rates of drainage and runoff of the burnt samples in the first run varied between the values of cover (low runoff, high infiltration) and bare (high runoff, low infiltration). Drainage in the ash-covered samples was twice as high as ashremoved samples. In the second run, both samples showed a similar response compared to bare conditions. These laboratory observations suggest that WR and protection by ash are factors to consider in assessing the erosion susceptibility of a burnt forest soil. Furthermore, possible management implications based upon this research are that: 1) ash can have several important roles immediately after a forest fire by protecting the forest soil from rain splash erosion, and with its high water holding capacity, absorbs rainfall, thereby reducing runoff; and 2) ash has no negative influence upon soil infiltration demonstrating the important benefits of ensuring the longer term maintenance of post-fire ash within the burnt landscape. Finally, management actions including mulching further enhance soil stability and minimize soil erosion.

Structured gravel river beds clearly exert a major influence on bed stability. Indexing structural stability by field measurements of bed strength neglects the processes operating to entrain and transport bed material in different parts of each structure. This study takes a morphological approach to interpreting the critical processes, using particle tracing to determine the movement of individual cluster particles over a range of flood event magnitudes and durations. The experiment was carried out on the River South Tyne, UK; it uses flow hydrographs measured nearby and also benefits from previous studies of historical development, channel morphology and sediment transport at the same site. More than 30 clusters were monitored over a seven-month period during which clusters occupied 7–16 per cent of the bed. Threshold flows delimiting three apparently contrasting bed sediment process regimes for cluster particles are tentatively set at 100 m3 s−1 and 183 m3 s−1; durations of flow at these levels are critical for cluster development, rather than flow peak values. Wake particles are transported most easily. Flow straightening in the wandering channel planform reduces the stability of clusters, since mechanical strength is markedly reduced by this change of direction. The overall area covered by clusters between significant transport events varies little, implying a dynamic equilibrium condition. Copyright © 2005 John Wiley & Sons, Ltd.

The concept of river-bed stability as indexed by the occurrence of stable bed forms was examined in humid-temperate perennial streams and in Mediterranean ephemeral streams. The study examined the structural patterns of bed forms and their spatial distribution between temperate-humid and Mediterranean streams. Study sites in Northumberland, UK, and Mt. Carmel, Israel, were selected for their morphometric similarity, despite the contrast in climate, vegetation and hydrological regime. Field-work was based on a large number of Wolman grain size distributions and structure measurements along cross-sections at seven sites; Differences in mean grain size of bed structures were estimated using the general linear model (GLM) procedure and Duncan's multiple range test. Based on field evidence, river-bed configurations were divided into structural categories, according to the depositional setting of each measured particle on the river bed. Statistical analysis confirmed former qualitative descriptions of small-scale bed forms. The study identified spatial segregation in bed form distribution. In general, 30-40% of the bed material in the surveyed perennial streams was clustered, in contrast to approximately 10% in the ephemeral counterparts. The sorting index revealed higher values for the perennial streams, namely 2.39-3.59 compared with 1.73-2.07 for the ephemeral counterparts. It is suggested that the degree of sediment sorting and the proportion of clusters are strongly related. Sediment sorting, sediment supply and the hydrological regime explain the mechanism of cluster formation. It is assumed that climate shifts or human interference within river basins might affect the regional characteristic flood hydrograph, and consequently alter the sedimentary character of the river bed. In the case where river bed stability is reduced owing to changes in cluster bed form distribution, rivers that normally do not yield a significant amount of sediment might be subject to notable sedimentation problems.

In the Mediterranean forest area of Israel, fires increase runoff and sediment yield rates relative to undisturbed forested land. The September 1989 fire covered an area of 4 km2 in the main recreation area of Mount Carmel, a typical Mediterranean forest area. The lithology is chalk and limestone, and about 40% of the burnt area has steep slopes, exceeding 30%. Three study plots were established in burnt and unburnt areas. Plots were located on 100–300 m2 areas with different slope exposures. Runoff and sediments were collected after each storm by a collector system. A hydrometric station was established, draining an area of 1 km2 in the burnt zone. Rainfall was measured by two recorders and several rain gauges at the experimental sites. In the first rainfall season after the fire, runoff and sediment yield were 500 and 100,000 times higher respectively in the burnt areas. Rainfall intensity is a dominant factor in runoff and sediment yield rates. In the measured basin, total runoff in the first year was 1.6%. Revegetation recovery of the area was rapid, as shown by the results from the second season: runoff decreased by one order of magnitude, from an average of 10 mm to 1.5 mm; sediment yield decreased by two orders of magnitude, from 1200 g m−2 to 10 g m−2. The third season 1991/1992, was an exceptionally rainy year and therefore runoff and sediment yield increased, but to less than in the first year. Runoff and sediment yield are related to vegetation cover, rainfall intensity, soil properties, slope steepness and exposure and fire intensity. Logging activities after fire increase sediment yields. Through its effects on vegetation cover and soil, fire severity increases the potential for erosion.

No records exist in the scientific literature about lightning fires in the eastern Mediterranean (EM). Although thunderstorms are frequent in winter, if spontaneous fire is ignited, it will immediately be extinguished by rain. No thunderstorms occur in summer, and therefore no favourable weather conditions for natural ignitions exist. In October 2014, the synoptic conditions over the EM comprised a Red Sea Trough (RST) with an easterly axis (a less frequent version of this system). A convective storm, accompanied by thunderstorms with intense local rains developed rapidly. Simultaneously, six wildfires were reported from different locations in northern Israel (in the EM). Lightning activity documented by the Israel Electric Co. was at the same time and locations as the reported wildfires. To the best of our knowledge, this is the first case recorded in recent history of wildfires in the EM as a result of lightning. Moreover, in the literature, the RST is associated with fires only when its axis is in a western position, thus driving very hot and dry air masses. A different way of thinking is needed on the potential of lightning in autumn as a possible cause of fires under different situations of the RST.

Forestry management is crucial in mitigating erosion processes after extensive fires in Mediterranean woodlands. Fire alters forest ecosystems, causing an increase in rates of geomorphic processes. The September 1989 fire in Mt. Carmel covered an area of 4 km2 in the main recreation area of a typical Mediterranean forest area. Six experimental plots, covering an area of 300-500 m(2) each, were established in order to determine the effect of forestry management practice on soil erosion after the fire; runoff and sediments were collected during and after each rainstorm. Rainfall was measured by two recorders and several rain gauges at the study site. During the first year following the fire, sediment yield was 100-500 times higher than on vegetated slopes. Sediment movement was increased mainly by the lack of vegetation. Results show that there is a clear trend of decrease in sediment yield between the first year and the next five. After this period the burnt areas recovered to similar rates of erosion as in the unburnt areas. The clearings of burnt logs by machine and cable sliding increased the sediment yield in the experimental plots. After vegetation development in the second season following the fire, no significant differences were found among the types of management practice plots.