Time filter

Source Type

Motagh M.,German Research Center for Geosciences | Motagh M.,Leibniz University of Hanover | Shamshiri R.,Norwegian University of Science and Technology | Haghshenas Haghighi M.,German Research Center for Geosciences | And 4 more authors.
Engineering Geology | Year: 2017

Decades of groundwater overexploitation for agriculture and industrial development have resulted in substantial land subsidence in the Rafsanjan plain of southeastern Iran. This work presents the results of an InSAR time series analysis obtained by the exploitation of Envisat, ALOS and Sentinel-1 (S1) SAR data archives between June 2004, and May 2016, to investigate land subsidence in the plain. The InSAR analysis revealed an area of approximately 1000 km2 within the study area showing subsidence of > 5 cm/year and locally exceeding 30 cm/yr in the last decade. This area of significant subsidence is limited in its spatial extent to the agricultural land and is partly influenced by Quaternary faults. The temporal and areal relationships of subsidence and groundwater level data suggest that a significant part of the observed subsidence in the Rafsanjan region is caused by intense groundwater extraction that has led to widespread compaction within the upper parts of the up to 300 m thick unconsolidated sediments, causing irreversible and inelastic deformation of the aquifer. The average volume storage loss of the aquifer system due to overexploitation is estimated to have been approximately 300 million cubic metre (mcm)/yr over the last decade. © 2017 Elsevier B.V.

Roesch-McNally G.E.,Us Forest Service Pacific Northwest Research Station | Basche A.D.,Union of Concerned Scientists | Arbuckle J.G.,Iowa State University | Tyndall J.C.,Iowa State University | And 3 more authors.
Renewable Agriculture and Food Systems | Year: 2017

Cover crops are known to promote many aspects of soil and water quality, yet estimates find that in 2012 only 2.3% of the total agricultural lands in the Midwestern USA were using cover crops. Focus groups were conducted across the Corn Belt state of Iowa to better understand how farmers confront barriers to cover crop adoption in highly intensive agricultural production systems. Although much prior research has focused on analyzing factors that help predict cover crop use on farms, there is limited research on how farmers navigate and overcome field-level (e.g. proper planting of a cover crop) and structural barriers (e.g. market forces) associated with the use of cover crops. The results from the analysis of these conversations suggest that there is a complex dialectical relationship between farmers' individual management decisions and the broader agricultural context in the region that constrains their decisions. Farmers in these focus groups shared how they navigate complex management decisions within a generally homogenized agricultural and economic landscape that makes cover crop integration challenging. Many who joined the focus groups have found ways to overcome barriers and successfully integrate cover crops into their cropping systems. This is illustrated through farmers' descriptions of their ‘whole system’ approach to cover crops management, where they described how they prioritize the success of their cover crops by focusing on multiple aspects of management, including changes they have made to nutrient application and modifications to equipment. These producers also engage with farmer networks to gain strategies for overcoming management challenges associated with cover crops. Although many participants had successfully planted cover crops, they tended to believe that greater economic incentives and/or more diverse crop and livestock markets would be needed to spur more widespread adoption of the practice. Our results further illustrate how structural and field-level barriers constrain individual actions, as it is not simply the basic agronomic considerations (such as seeding and terminating cover crops) that pose a challenge to their use, but also the broader economic and market drivers that exist in agriculturally intensive systems. Our study provides evidence that reducing structural barriers to adoption may be necessary to increase the use of this conservation practice to reduce environmental impacts associated with intensive agricultural production. Copyright © Cambridge University Press 2017 This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (, which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.

Mirzaee S.,University of Tehran | Motagh M.,University of Tehran | Motagh M.,German Research Center for Geosciences | Arefi H.,University of Tehran | Nooryazdan M.,Forest
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2014

Due to its special imaging characteristics, Synthetic Aperture Radar (SAR) has become an important source of information for a variety of remote sensing applications dealing with environmental changes. SAR images contain information about both phase and intensity in different polarization modes, making them sensitive to geometrical structure and physical properties of the targets such as dielectric and plant water content. In this study we investigate multi temporal changes occurring to different crop types due to phenological changes using high-resolution TerraSAR-X imagers. The dataset includes 17 dual-polarimetry TSX data acquired from June 2012 to August 2013 in Lorestan province, Iran. Several features are extracted from polarized data and classified using support vector machine (SVM) classifier. Training samples and different features employed in classification are also assessed in the study. Results show a satisfactory accuracy for classification which is about 0.91 in kappa coefficient.

Bose P.,Carleton University | Douieb K.,Forest | Iacono J.,New York University | Langerman S.,Free University of Colombia
Algorithmica | Year: 2016

A static binary search tree where every search starts from where the previous one ends (lazy finger) is considered. Such a search method is more powerful than that of the classic optimal static trees, where every search starts from the root (root finger), and less powerful than when rotations are allowed—where finding the best rotation based tree is the topic of the dynamic optimality conjecture of Sleator and Tarjan. The runtime of the classic root-finger tree can be expressed in terms of the entropy of the distribution of the searches, but we show that this is not the case for the optimal lazy finger tree. A non-entropy based asymptotically-tight expression for the runtime of the optimal lazy finger trees is derived, and a dynamic programming-based method is presented to compute the optimal tree. © 2016, Springer Science+Business Media New York.

Saadat H.,McGill University | Adamowski J.,McGill University | Tayefi V.,University of Tehran | Namdar M.,Forest | And 2 more authors.
Catena | Year: 2014

Having accurate soil erosion intensity/type maps using satellite imagery is not generally a difficult task. However, there are still difficulties for the generation of small scale erosion features at regional and national levels. It is even more problematic when high-resolution satellite images cannot be used due to their high cost at a regional level. The principal objective of this study is to investigate the applicability of brightness value to generate accurate interrill and rill erosion intensity maps using medium resolution satellite images at a regional level. In this study, Landsat ETM+ images are used and the Golestan dam watershed with an area of 4511.8km2 located at northeast of Iran is selected as the study area. In order to generate a Homogeneous Land Unit (HLU) map, three ancillary layers including slope, landform, land use and land cover, are overlayed on each other. The HLUs are used in a supportive role for identifying appropriate sampling points across the entire study area, at which the degrees of interrill and rill erosions are measured. The ground-truth erosion information collected at the 1328 locations is divided into training and reference data sets. Using the Tasseled Cap transformation technique, the brightness value of each pixel at the beginning (May), middle (July) and end (September) of growing season is obtained. By subtracting the May brightness value (BM) from the July one (BJ), and the July brightness value from the September one (BS), two new brightness images representing the brightness variations over May-July (BMJ) and July-September (BJS) are created. The two new brightness images are combined to generate a map where its pixels indicate the state (i.e. increase, I, decrease, D, and constant, C) of brightness variation over the two growing seasons. Using the measured interrill and rill erosion information at the training sampling locations, a unique relationship is found between the trend of brightness variation and the erosion intensity. This relationship is validated using the reference data sets. The results show that the proposed method is able to produce an interrill-rill erosion intensity map with an overall field-checked accuracy of 96% at this study location. The main advantages of this method are its high accuracy, its lower demands on time and funds for field work, and the ready availability of required data. © 2013 Elsevier B.V.

Saadat H.,McGill University | Adamowski J.,McGill University | Bonnell R.,McGill University | Sharifi F.,Soil Conservation and Watershed Management Research Institute SCWMRI | And 2 more authors.
ISPRS Journal of Photogrammetry and Remote Sensing | Year: 2011

Accelerated soil erosion, high sediment yields, floods and debris flow are serious problems in many areas of Iran, and in particular in the Golestan dam watershed, which is the area that was investigated in this study. Accurate land use and land cover (LULC) maps can be effective tools to help soil erosion control efforts. The principal objective of this research was to propose a new protocol for LULC classification for large areas based on readily available ancillary information and analysis of three single date Landsat ETM+ images, and to demonstrate that successful mapping depends on more than just analysis of reflectance values. In this research, it was found that incorporating climatic and topographic conditions helped delineate what was otherwise overlapping information. This study determined that a late summer Landsat ETM+ image yields the best results with an overall accuracy of 95%, while a spring image yields the poorest accuracy (82%). A summer image yields an intermediate accuracy of 92%. In future studies where funding is limited to obtaining one image, late summer images would be most suitable for LULC mapping. The analysis as presented in this paper could also be done with satellite images taken at different times of the season. It may be, particularly for other climatic zones, that there is a better time of season for image acquisition that would present more information. © 2011 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS).

Garshasebi P.,Forest | Shafaghati M.,Forest | Djazi H.,Islamic Azad University at Semnan
Sustainable Watershed Management - Proceedings of the 2nd International Conference on Sustainable Watershed Management, SUWAMA 2014 | Year: 2014

Comprehensive watershed management plans must be realistic and yet have an insightful perspective on various aspects nationally and regionally. A general conservation area (soil, water would only cover, etc.) can prevent erosion, sediment transport, flood risk and drought damage, and sustainability of the water regime of rivers causes geometric characteristics and optimal utilization of available resources. For the purposes of valuation and economic evaluation of the physical and economic impacts of projects and also to provide an appropriate framework, the selection of compatible and indicators needs to be determined in addition to determining the benefits, physical and economic effects of the economic efficiency of projects as well as manner conducting them. The aim of this work is to provide a framework for economic evaluation of watershed projects so it's possible to apply ecosystem-friendly choices at lower costs and provide more future revenue. Physical impact assessment and economic feasibility study of watershed management action and the effects of economic data are converted based on the index (B/C), the estimated cost of the project is executed, and the bases of its profits are used. Evaluation shows that rehabilitation of watershed with discount rate of 15 percent during a period of 30 years will be justified economically in lands with low and relative productivity, and implementing soil conservation activities in mountainous rangelands and hilly badlands with high soil erosion will have a positive net present value. Also, developing new springs, the potential of their irrigation, conserving lands, roads and buildings against flood hazard and conserving reservoirs against sediment deposition consists of 48, 20 and 7 percent of total benefits of NPV in rehabilitated watershed. In this studywe conducted a field investigation of the Projects, the set of indicators and identified their projects' valuation methods, and compared the costs and benefits of watershed management projects. This included the physical implications (of projects), financial and economic consequences (increased production and income of residents in the areas of direct and indirect impact), environmental impacts (changes in ground water quality, soil erosion, biodiversity, water levels surface and groundwater, wildlife habitat, soil salinity and alkalinity, etc.) and various assessments mentioned including environmental, social, economic, and distribution and presentation of case studies. © 2015 Taylor & Francis Group.

PubMed | Forest.
Type: Journal Article | Journal: Nursing standard (Royal College of Nursing (Great Britain) : 1987) | Year: 2016

Addenbrookes Hospitals decision to re-introduce smoking rooms is a step forward (News May 6). A total ban produces three major problems.

PubMed | Forest.
Type: Journal Article | Journal: Nursing standard (Royal College of Nursing (Great Britain) : 1987) | Year: 2016

Congratulations to Leeds General Infirmary for resisting the prohibitionist demands of the anti-smoker Utopianists and deciding to reintroduce smoking provision for both patients and staff.

PubMed | Forest.
Type: Journal Article | Journal: Nursing standard (Royal College of Nursing (Great Britain) : 1987) | Year: 2016

The findings of WHOs research into the alleged risk to non-smokers of exposure to environmental tobacco smoke confirm that it in no way constitutes the threat that the antismoker industry would have us all believe.

Loading Forest collaborators
Loading Forest collaborators