Time series analysis of vegetation-cover response to environmental factors and residential development in a dryland region

Land-use changes as a result of residential development often lead to degradation and alter vegetation cover (VC). Although these are worldwide phenomena, sufficient knowledge about anthropogenic effects caused by various populated areas in dryland ecosystems is lacking. This study explored anthropogenic development in rural areas and its effects on the conservation of protected areas in drylands, focusing on the change in VC, the reasons, extent, and the drivers of change. We propose a novel framework for exploring VC change (VCC) as a function of environmental and human-driven factors including different types of populated areas in drylands. As a case study, we used a 30-year time series of Landsat satellite images over the arid region of Israel to analyze spatiotemporal VCC. The temporal analysis involved the Contextual Mann-Kendall significance test and spatial analysis to model clustering of VCC. A Gradient Boosted Regression machine learning algorithm was applied to study the relative influence of environmental and human-driven factors on VCC. In addition, we used ANOVA to examine differences between the effects of three types of populated areas on the spatiotemporal trends of VC. The results show that the most influential environmental variable on VCC was elevation (relative contribution of 17%), followed by slope (14.8%) and distance from populated areas (14.6%). Moreover, different types of populated areas affected VC differently with varying distances from residential centroids. The nature reserves increased VC positively and significantly, while livestock settlements had a negative effect. Change in vegetation was mostly confined to the stream network and occurred in lower elevations. The study demonstrates how different land-use practices alter the landscape in terms of VC and differ in their extents, patterns, and effects. With the expected growth in population and residential development worldwide, the proposed framework may assist conservation managements and policy makers in minimizing environmental degradation in drylands.     

Thermodynamically consistent non-local damage formulation for fluid-driven fracture in poro-viscoelastic media

Acta Geotechnica - We present a novel non-local integral-type damage formulation for hydraulic fracture of poro-viscoelastic media under the framework of irreversible thermodynamics. The...     

Regional and local climatic effects on the Dead-Sea evaporation

The natural evaporation in the Dead-Sea is a very important meteorological parameter to the local industries at Sdom. It was found that the pan evaporation in Sdom has recently increased by 20?C25%. In this paper we explore the reasons for this increase. It is found that both large-scale and local climatic changes have contributed to the evaporation increase in the Dead Sea Valley. The large-scale (global) change potentially associated with the global warming, resulted in changes of the frequencies of some synoptic systems in the region. The local change is a result of the recent Dead-Sea drying, which reduced the local Dead-Sea breeze while intensifying the Mediterranean-Sea breeze penetrating the Dead Sea Valley. It is suggested that while the local effect was the dominant climatic change factor in the Dead-Sea Valley in the 1970?C1990, the global effect becomes the dominant one in the more recent evaporation increase in the Dead-Sea.     

Extracting spatial patterns in bicycle routes from crowdsourced data

Much is done nowadays to provide cyclists with safe and sustainable road infrastructure. Its development requires the investigation of road usage and interactions between traffic commuters. This article is focused on exploiting crowdsourced user‐generated data, namely GPS trajectories collected by cyclists and road network infrastructure generated by citizens, to extract and analyze spatial patterns and road‐type use of cyclists in urban environments. Since user‐generated data shows data‐deficiencies, we introduce tailored spatial data‐handling processes for which several algorithms are developed and implemented. These include data filtering and segmentation, map‐matching and spatial arrangement of GPS trajectories with the road network. A spatial analysis and a characterization of road‐type use are then carried out to investigate and identify specific spatial patterns of cycle routes. The proposed analysis was applied to the cities of Amsterdam (The Netherlands) and Osnabrück (Germany), proving its feasibility and reliability in mining road‐type use and extracting pattern information and preferences. This information can help users who wish to explore friendlier and more interesting cycle patterns, based on collective usage, as well as city planners and transportation experts wishing to pinpoint areas most in need of further development and planning.     

Integrated cave drip monitoring for epikarst recharge estimation in a dry Mediterranean area,Sif Cave,Israel

Understanding recharge mechanisms and controls in karst regions is extremely important for managing water resources because of the dynamic nature of the system. The objective of this study was to evaluate water percolation through epikarst by monitoring water flow into a cave and conducting artificial irrigation and tracer experiments, at Sif Cave in Wadi Sussi, Israel from 2005 through 2007. The research is based on continuous high‐resolution direct measurements of both rainfall and water percolation in the cave chamber collected by three large PVC sheets which integrate drips from three different areas (17, 46, and 52 m²). Barrels equipped with pressure transducers record drip rate and volume for each of the three areas. The combined measured rainfall and cave data enables estimation of recharge into the epikarst and to better understand the relationship of rainfall‐recharge. Three distinct types of flow regimes were identified: (1) ‘Quick flow’ through preferential flow paths (large fractures and conduits); (2) ‘Intermediate flow’ through a secondary crack system; and (3) ‘Slow flow’ through the matrix. A threshold of ～100 mm of rain at the beginning of the rainy season is required to increase soil water content allowing later rainfall events to percolate deeper through the soil and to initiate dripping in the cave. During winter, as the soil water content rises, the lag time between a rain event and cave drip response decreases. Annual recharge (140–160 mm in different areas in the cave) measured represents 30–35% of annual rainfall (460 mm). Copyright © 2011 John Wiley & Sons, Ltd.     

Assessing the impact of climate change on representative field crops in Israeli agriculture: a case study of wheat and cotton

Climate changes, associated with accumulation of greenhouse gases, are expected to have a profound influence on agricultural sustainability in Israel, a semi-arid area characterized by a cold wet winter and a dry warm summer. Accordingly this study explored economic aspects of agricultural production under projected climate-change scenarios by the “production function” approach, as applied to two representative crops: wheat, as the major crop grown in Israel’s dry southern region, and cotton, representing the more humid climate in the north. Adjusting outputs of the global climate model HadCM3 to the specific research locations, we generated projections for 2070–2100 temperatures and precipitations for two climate change scenarios. Results for wheat vary among climate scenarios; net revenues become negative under the severe scenario (change from −145 to −273%), but may increase under the moderate one (−43 to +35%), depending on nitrogen applied to the crop. Distribution of rain events was found to play a major role in determining yields. By contrast, under both scenarios cotton experiences a considerable decrease in yield with significant economic losses (−240 and −173% in A2 and B2 scenarios, respectively). Additional irrigation and nitrogen may reduce farming losses, unlike changes in seeding dates.     

Elongation and migration of sand dunes

Two distinct processes are known to act on dynamic dunes, the process of migration by erosion on the windward side and deposition on the lee side, typical for transverse dunes, and the process of elongation typical for linear dunes. These two processes are determined by wind direction relative to the dune alignment. This article reviews the assertion that linear dunes experience lateral displacement in addition to elongation. Fieldwork on vegetated linear dunes (VLDs) and GIS work on seif dunes indicates no lateral migration for these dunes. Linear dunes can shift laterally only when a slip face, formed on the lee side, reaches the plinth of the dune. The winds from both sides of the seif dune are never symmetric; usually winds from one direction are more dominant and effective. The outcome is the formation of peaks and saddles along the dune. The strongest winds create a slip face on the lee side of the peak segments of the dune, oblique to the dune alignment, which reaches the base of the dune and displaces the peak downwind along the dune alignment. The internal structure of the seif dune is formed mostly by this dominant wind direction and gives the impression that the dune has shifted laterally. On the other hand, there are cases in which the wind directions relative to dune alignment fall between those of transverse and seif dunes. In such cases, both processes act on the dune, which subsequently experiences migration as well as elongation.     

Feasibility Study of In-Well Vapor Stripping Using Airlift Pumping

This study tests the feasibility of an aquifer remediation concept proposed by Gvirtzman and Gorelick (1992) that involves the removal of volatile organic compounds (VOCs) dissolved in ground water. The principal is 10 inject air into a well, creating airlift pumping, which is used as a means of in-well vapor stripping. The partially treated water is diverted away from the well and infiltrates back to the water table, thus allowing remediation of a larger aquifer volume.
A remediation well prototype, constructed in a laboratory aquifer model, was used to demonstrate the processes involved. The removal rates of trichloroethylene, toluene, and chloroform were monitored using eight triple-level observation wells. The continuous decrease of VOC concentrations during the short-term experiment has yielded macroscopic evidence that the process offers some promise. It was found that the flow field in the saturated zone. involving the continuous water circulation between the pumping well and the recharging area, caused temporal and spatial variation in remediation efficiency.     

Desertification in Northern Sinai in the eighteenth century

Several natural and anthropogenic phenomena in the northern Sinai sand sea and the northern Negev desert were caused by desiccation of the area during most of the 17^th and the 18^th century. The dry phase had been preceded by a wet period. It appears that the combination of several wet decades followed by a long period of desiccation was the cause of desertification processes in the area which then triggered the destruction of vegetation.There is some congruity between the wet period and the period of maximum sunspot activity, known as theMedieval Maximum, while the desiccation of the area which followed coincided approximately with the period of minimum solar activity, known as theMaunder Minimum.     

The distribution of Autumnal Easterly Wind Spells Favoring Rapid spread of forest wildfires on Mount Carmel,Israel

Wildfires became a severeecological and financial problem in Israel during the last few years. A significant increase in the incidence of severe wildfires in natural shrublands and planted forests as arson was observed. On 19–20. 9. 89 a large wildfire ignited as an act of terrorism, devastated large parts of Mt. Carmel forests.Weather conditions during a wildfire have an important role in the determination of the rate of spread of the fire. This depends mainly on the availability of dry matter and the wind speed. Two factors that reach their optimum at the end of the summer in September and October during Sharav episodes. The distribution of easterly wind spells associated with Sharav events is considered. The results show that there is no climatic limitation to a spread of a wildfire of the same order of magnitude as the last one, every year.