| چکیده انگلیسی مقاله |
1- Introduction
Desertification in arid and semi-arid areas is an invisible and very dangerous phenomenon, and if it continues, it leads to the destruction of the land and the loss of renewable natural resources. Several factors play an effective role in the occurrence of desertification in a region, among which the phenomenon of land subsidence can be mentioned. Land subsidence is a geological process that occurs in a long-term balance and coordination between human activities and the hydrogeological environment. Today, land subsidence caused by the extraction of underground water has become a global problem, and it can even be the site of other hazards and threaten the society. The challenge of establishing a balance between groundwater consumption and land subsidence control is essential for sustainable development and curbing desertification. In order to meet their needs, including agriculture, industry and drinking, human societies depend on underground water sources and provide the required water through underground water. These conditions have become more severe in Iran due to its location in the arid and semi-arid belt, along with the improper distribution of rainfall with excessive extraction of underground water. In Iran, this phenomenon has extensive ecological, economic, social and environmental consequences due to the multiplicity, extent and complexity of the environmental and human factors that cause desertification. Hence, the precise monitoring and analysis of the intensity of desertification is of great importance for risk assessment and risk assessment. Therefore, it is necessary to know the criteria and indicators effective in the occurrence of desertification in order to achieve a model that can monitor the intensity of desertification in order to manage and plan the desert areas correctly and on principles. For this purpose, the aim of this research is to evaluate the state of desertification by IMDPA model based on two criteria of underground water and subsidence in the Rafsanjan watershed located in the northwest of Kerman province.
2- Methodology
In this research, two criteria of underground water and subsidence rate were used as key criteria to prepare the desertification intensity map. According to the available information and the goals of this research, the criteria of underground water were scored based on electrical conductivity indicators, sodium absorption ratio, and groundwater level drop. For the subsidence criterion, the subsidence rate index was used in the year 2014-2015. In the next stage, a weight between 1 and 4 was given to each index based on its effect on desertification. The weighting is linear and equal in proportion; So that value 1 is the best and value 4 is the worst weight. Zoning of the mentioned indicators was also done by geographic information system and interpolation methods. The subsidence criterion was evaluated using the subsidence map prepared from Sentinel 1 satellite images in the year 2014-2015. In the end, the final map of the desertification situation was obtained according to the IMDPA model and based on the geometric mean of the criteria.
3- Results
The average electrical conductivity measure in Rafsanjan watershed was 9351.4, which with a score of 4, is in a very severe desertification situation. Also, in terms of absorbable sodium, this watershed with an average of 12.28 and a score of 1, put it in a state of low desertification. In addition, according to the results of the groundwater quantity criterion based on the average level drop for the aquifer located in the Rafsanjan watershed, it was determined that the average drop of groundwater is about 54 cm with a score of 4, and is in a severe state of desertification. The subsidence of the aquifer located in the Rafsanjan watershed has varied from seven to less than one centimeter per year. Also, based on the average values, the average subsidence in the water year 1394-1395 in the region was in the low category with an average of -1.25 and a score of 1. Examining the areas with subsidence and the level of the drop in the underground water level showed that the drop in the underground water level can be considered as the main reason for the subsidence in the Rafsanjan aquifer. The overlap of three indicators of groundwater criteria, including: electrical conductivity, sodium absorption ratio and level drop, showed that 2.74, 59.07, 37.15 and 1.02 percent of Rafsanjan watershed are in low, medium, severe and There is a lot of desertification. Also, the overlap of the underground water and land subsidence criteria showed that the intensity of desertification is placed in three levels: low, moderate and severe, and the highest level corresponds to the moderate severity.
4- Discussion & Conclusions
Rafsanjan watershed is one of the critical areas of subsidence. For this purpose, it is very important to evaluate land degradation caused by subsidence and drop in the underground water level in the Rafsanjan watershed. The results of this research confirm that according to the underground water criteria, the average electrical conductivity, absorbable sodium, and the drop in the water level of the region are in very severe, low, and severe desertification. In addition, in terms of the intensity of desertification from the point of view of water quality, the region is located in low, medium, severe and very severe classes. Finally, the intensity of desertification according to the two investigated criteria (underground water and subsidence) is placed in three levels: low, medium and severe, and the highest level is related to moderate severity. The results of this research will create a clear horizon for managers and planners of the natural resources sector, which will lead to a precise understanding of the criteria and indicators effective in the occurrence of desertification in the region. In addition, it is suggested to identify other effective factors in the region and introduce them to the desired model for accurate estimation of this phenomenon.
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| نویسندگان مقاله |
سید مسعود سلیمانپور | Seyed Masoud Soleimanpour
Soil Conservation and Watershed Management Research Department, Fars Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Shiraz, Iran.
بخش تحقیقات حفاظت خاک و آبخیزداری، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی، شیراز، ایران.
مریم نعیمی | Maryam Naeimi
Desert Research Department, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran.
بخش تحقیقات بیابان، مؤسسه تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات آموزش و ترویج کشاورزی، تهران، ایران.
امید رحمتی | Omid Rahmati
Soil Conservation and Watershed Management Research Department, Kurdistan Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Sanandaj, Iran.
بخش تحقیقات حفاظت خاک و آبخیزداری، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان کردستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، سنندج، ایران.
محبوبه معتمدنیا | Mahboobeh Moatamednia
Natural Resources and Watershed Management Department, Bafgh County, Yazd Province, Iran.
اداره منابع طبیعی و آبخیزداری شهرستان بافق، استان یزد، ایران.
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