Esmaeel Rahbar; Mojtaba Pakparvar; Masoud Masoudi; Ladan Jokar
Volume 12, Issue 4 , August 2019, , Pages 357-375
Abolghasem Dadrasi Sabzavari; Mojtaba Pakparvar
Volume 14, Issue 1 , January 2007, , Pages 33-52
Abstract
Desertification is one of the most difficult issues which has been taken into consideration in the world. The main objective of this study is determination of lands affected by desertification using remote sensing and geographic information systems, in Sabzevar. To meet the objective, Satellite ...
Read More
Desertification is one of the most difficult issues which has been taken into consideration in the world. The main objective of this study is determination of lands affected by desertification using remote sensing and geographic information systems, in Sabzevar. To meet the objective, Satellite imagery of Landsat TM- 29 April 1987 and 13 May 2001 were selected and used, after haze and geometric correction. Principal Components (PC) and False Color Composit (FCC) were calculated, finally FCC521: RGB was selected for background of classification because of the best correlation. The Satellite images were classified by the maximum likelihood algorithm on the basis of field data. A study was conducted to determine the iso line of change in groundwater salinity and depth, in the study area, by using subsurface water data ( quality and quantity). The results show that on non saline parts and in the area of gypsum, the changes are negligible. The area of land uses are more or less the same except in agriculture which the land has increased by 3632 ha and in urban area which developed 672 ha. Merging and processing the whole data shows that the agriculture lands increased from 1987 to 2001. More salinity and less depth of groundwater are the results of groundwater data analysis, specially in south east part of the region
Ebrahim khalifeh; Mohammad reza Kavianpoor; Mojtabah Pakparvar; Sajad Vafaei
Volume 14, Issue 2 , January 2007, , Pages 204-221
Abstract
Wind erosion is one of the major problems in arid and semiarid regions, where the erosion and sand transport caused by wind can lead to serious problems for civilians live in those areas. The regions under wind erosion, includes the sources, transition and deposition areas. Amongst them, identification ...
Read More
Wind erosion is one of the major problems in arid and semiarid regions, where the erosion and sand transport caused by wind can lead to serious problems for civilians live in those areas. The regions under wind erosion, includes the sources, transition and deposition areas. Amongst them, identification of the sources areas is significantly important, which affects our investigations, evaluation and control over wind erosion. It has been found that the application of Remote Sensing (RS) techniques and Geographical Information Systems (GIS) is considerably useful to find the sources of sand in wind erosion. In this study, a combination method based on Image Processing and Wind Analysis (IPWA) has been introduced and used to identify the sources of deposited sand in areas under wind erosion. The method is based on utilizing and composing of image processing techniques such as image enhancement, threshold, false color composition, filtering, and Spectral Profile Testing and Analysis. The results are compared with other investigations to validate the method. It was observed that the results of the present method are well comparable with those of previous researches which are highly based on field investigations. Without extensive field measurements, the method reduces the time and the cost of investigation and provides a basis for repeating the operation at any time and everywhere, which is required.
Gholam reza Ghahari; Mojtabah Pakparvar
Volume 14, Issue 3 , January 2007, , Pages 368-390
Abstract
The artificial recharge of groundwater (ARG) is a proven method of increasing the water level in unconfined aquifers. Although the ARG activities at the Kowsar Station have been proven successful due to an 8 fold increase in the area of irrigated farm fields, quantitative studies are lacking. We have ...
Read More
The artificial recharge of groundwater (ARG) is a proven method of increasing the water level in unconfined aquifers. Although the ARG activities at the Kowsar Station have been proven successful due to an 8 fold increase in the area of irrigated farm fields, quantitative studies are lacking. We have been monitoring floodwater discharge and diversion to our ARG system and the piezometric level since 1992. These data were used to establish a relationship between the ARG events and the water table variations at the study site. Firstly, the water tables (WTL) at the time of recharge, and for 3 months after it, were grouped and the equipotential lines for the aquifer were constructed. Then the same data were grouped according to the months corresponding with the minimum and maximum pumping. It was observed that all piezometer, showed a rise in WTL for 3 months during the Oct. - Feb. period if there was an ARG event. The trend was reversed when there was heavy pumping during the irrigation season; thus the aquifer was sinking. The general trend in the area indicates an overdraft from the aquifer. It is interesting to note that the WTL in piezometer No. 2, which is located in the center of the ARG systems, shows a gradual rise, in spite of the opposite observation in other 3 piezometers. The lowest WTL is observed in piezometer No. 4, which is located at the center of irrigated fields.
Ebrahim khalifeh; Mojtabah Pakparvar; Mohammad reza Kaviyanpoor
Volume 14, Issue 3 , January 2007, , Pages 403-420
Abstract
Active sand dunes particularly barkhans are serious threats for adjacent civilians live, agricultural lands and economic activities. Deployment quality and motion paths of these dunes are main targets in wind erosion studies in deposit regions. These targets need the active and inactive dunes to be identified. ...
Read More
Active sand dunes particularly barkhans are serious threats for adjacent civilians live, agricultural lands and economic activities. Deployment quality and motion paths of these dunes are main targets in wind erosion studies in deposit regions. These targets need the active and inactive dunes to be identified. Edges and borders are evident characteristics of wind deposits and sand dunes. Inactive (old) dunes are more voluminous and smooth. Furthermore active dunes have distinct feature. Also temperature, humidity and plant cover variation lead to change surface and feature of inactive dunes. These changes can’t be observed in one band images. Therefore making uses of filters particularly non directional edges enhancement and band ratio techniques are main ideas to process the images of these dunes especially about their activity and displacement. In present research filter and band ratio techniques have been used and consequently, third band in Profile Testing and Spectral Analysis method (in this case study b5 of Landsat ETM+) and ratio of first and second bands (in this case study b62/b4) have been introduced respectively as appropriate band and ratio for these techniques to identify and separate active (new) and inactive (old) sand dunes.