hamidreza abbasi; Mahmood rajabi aleni; sadat feiznia; Mohammad Darvish; mamak ahmadian; ali shahbazi
Volume 22, Issue 3 , November 2015, , Pages 583-594
Mehdi Ahmadian; Moloud Sadat chavoshian; Mohammad Darvish
Volume 22, Issue 1 , June 2015, , Pages 109-120
Abstract
In recent years, the depletion of groundwater resources has been increased by the population explosionand the development of agriculture and industry. In this study, the geo-statistical methods were used to study the spatial and temporal variations in groundwater level in Kaboudrahang-Famenin plain. ...
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In recent years, the depletion of groundwater resources has been increased by the population explosionand the development of agriculture and industry. In this study, the geo-statistical methods were used to study the spatial and temporal variations in groundwater level in Kaboudrahang-Famenin plain. For this purpose, available data of region including information about piezometers and monitoring wells were collected and then, database was composed. Next, the control of data accuracy was carried out. For comparison of geo-statistical methods, the variograms were plotted respectively and the different interpolation methods such as kriging (simple model), cokriging and Inverse Distance Weight with powers 1 to 5 (IDW) and radial basis functions (Thin Plate Radial Function, Inverse Multi Quadratic and Multi Quadratic) for groundwater zoning were used. The best interpolation method was selected by using two criteria, Root Mean Square (RMSE) and General Standard Deviation (GSD), and finally the zoning map of groundwater level was drawn in Arc-GIS software. The results of spatial statistical analysis indicated that the best variogram models for groundwater level data in the first period (1989), in the middle period (1993&1999) and the last period (2006) were spherical, circular and pentaspherical models, respectively.Evaluation of various interpolation methods with using "cross validation criteria" showed that in the investigation period, cokriging had the lowest estimation error compared with other interpolation methods. Thus, Cokriging was the most suitable interpolation method. The results of interpolated digital maps during the study period showed that the maximum fall of water table in 17 years was recorded to be 55 meters for central east region of plain. This shows the dramatic reduction in groundwater reserves of the region, which would not lead to industrial and agricultural sustainable development.
Mehdi Ahmadian; Mohammad Darvish; Mohammadreza Sadeghi Manesh
Volume 21, Issue 4 , March 2015, , Pages 604-619
Abstract
A temporary model to assess desertification and providing the map of land susceptibility to the reducing processes of land efficiency was proffered by FAO and UNEP. The results of regional implementation of the FAO and UNEP method in Gharachay watershed are presented in this article. In this method, ...
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A temporary model to assess desertification and providing the map of land susceptibility to the reducing processes of land efficiency was proffered by FAO and UNEP. The results of regional implementation of the FAO and UNEP method in Gharachay watershed are presented in this article. In this method, five major processes of land degradation were evaluated with two aspects including "current status" and "inherent risk". For any of these aspects, the maps of low, moderate, severe, and very severe desertification were separated and the area of each class was calculated. Then, the maps of main processes affecting desertification were integrated together and two maps including "current status and inherent risk" were provided. Afterward, the maps of livestock pressure and human population were prepared. In order to obtain the total risk of desertification, the four mentioned maps were integrated and finally the risk of desertification classes were calculated. In view of the current desertification status in the studied region, the following results were obtained: The highest vegetation decline (76%) was observed in the east, south, and center of the region. The highest percentage of water and wind erosion (45.2%, 57.9%) was obtained in the south and east respectively; the highest soil salinization (34.7%) was observed in the east. In addition, the highest loss of groundwater resources was observed in the center and east of the region. The highest livestock pressure (58.3%) was recorded in the center of region; however, population pressure had little impact on environmental degradation. The area of each category, including low, moderate, severe, and very severe, was calculated to be 39.4, 27.9, 25.1, and 7.3 percent, respectively. Overall, according to the obtained results, the natural and human factors, particularly livestock pressure, were effective to create these conditions.
Seyed Jafar Seyed Akhlaghi; Hamid Reza Abbasi; Ammar Rafiee Imam; Mohammad Darvish
Volume 19, Issue 3 , December 2012, , Pages 498-511
Abstract
Desertification is a multifactorial phenomenon and relates to different aspects. Thus, this concept can be studied around multiple axes in natural resources and environment. Nowadays, the rapid growth and huge population in environments and ecological areas are of the most important concerns that have ...
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Desertification is a multifactorial phenomenon and relates to different aspects. Thus, this concept can be studied around multiple axes in natural resources and environment. Nowadays, the rapid growth and huge population in environments and ecological areas are of the most important concerns that have attracted the attention of experts and planners to the concept of desertification or combat desertification .On the one hand, astounding growth of metropolises and unbridled industrial development have led to adverse outcomes for the residents. Moreover, land is a limited resource and the situation will get worse over time in many countries due to the exponential growth of population and extensive use of land and with regard to the fact that only 5 million km2 of the earth has remained for sustainable utilization in future. There are many issues surrounding population supporting capacity based upon the quality of the land in order to maintain the sustainability of resources and environment. The purpose of this article was to estimate population supporting capacity of Tehran and Alborz on the basis of the potential of land units through the method introduced by Central Department of Agriculture of USA. This is the first step to determine the extent of land degradation and detection of man-made desertification. In the current situation, it is obvious that a demographic development of Alborz and Tehran provinces has led to instability in the environment and desertification. Based on the results, classes 1, 4 and 9 of the land quality covered 20.38, 14.93, and 37.44 percent of the surface area, respectively. These three classes could be accounted for 81.9% of population supporting capacity according to the potential of production. Our results showed that lands of the study area were exposed to desertification classified as very high risk (38.55 % of the total area), high risk (25.06 % of the total are), moderate risk (23 % of the total area), and low risk (13% of the total area). Accordingly, it was found that the current population of Tehran province was 5 times higher than the optimal population. This ratio also reaches 4.7 times in high-density areas such as Tehran, Karaj, Shahriar and Robat Karim.
Mohammad mahdi Fatahi; Mohammad Darvish; Hamid reza Javid kia; Mahdi Adnani
Volume 17, Issue 4 , November 2011, , Pages 575-588
Abstract
Desertification is defined as the reduction of biomass potential and degradation of environmental resources and ecosystems which affects regional and cross-regional levels of human life.Assessment and mapping of desertification in Daryache Namak watershed with a 1614176 hectares area were considered ...
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Desertification is defined as the reduction of biomass potential and degradation of environmental resources and ecosystems which affects regional and cross-regional levels of human life.Assessment and mapping of desertification in Daryache Namak watershed with a 1614176 hectares area were considered as the aim of the current research. Desertification aspects were determined from vegetation degradation, water and wind erosion, quantitative and qualitative loss of water resources and soil salinization using FAO-UNEP method.Desertification was classified by overlaying and averaging of current status and natural capacity and all maps were made in GIS. According to the results, vegetation degradation (23.25%) and water resources degradation (59.63%) included the most area in current status and natural capacity of the study area respectively. Desertification total risk was also classified and mapped considering current status, natural capacity and human impacts and results indicated that 23.51, 76.47 and 0.02 percent of this watershed located in moderate, severe and very severe desertification classes respectively.