1- 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.
2- Desert Research Department, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran.
3- 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.
4- Natural Resources and Watershed Management Department, Bafgh County, Yazd Province, Iran.
2- Desert Research Department, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran.
3- 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.
4- Natural Resources and Watershed Management Department, Bafgh County, Yazd Province, Iran.
Abstract: (35 Views)
Introduction and Objective: Desertification is a process that causes irreversible changes in the soil and vegetation conditions of a region, leading to an increase in dryness and reduced productivity potential. The destruction of ground water resources, along with other processes, has been characterized as factors affecting desertification due to the limitations of water resources, reduction of water quality, and excessive exploitation. Subsidence, which is considered the final stage of desertification, will result from the increased use of groundwater resources. Knowing the processes and factors of desertification, as well as their intensity and weakness, is essential for proper management and planning in this context. Ground monitoring is an effective way to monitor desertification. Various models have been presented to evaluate the effectiveness factors in desertification and create related maps for this purpose. Various indicators and criteria can be used by the IMDPA model to efficiently examine the desertification status of each region in the meantime.
Materials and Methods: The desert watershed in Daranjir, located in the north of Kerman province and south of Yazd province, includes 12 study areas. The elevation ranges from 925 m in the Daranjir desert to 4465 m in the Kuh Hezar Mountain. The watershed covers an area of about 22,406 km2, while the deserts, salt marshes, plains, and foothills cover an area of 28,102 km2. The Daranjir desert, which measures 1000 km2, is deemed to be the end of the basin's surface and underground water drainage network. Groundwater data was utilized initially to investigate and study soil degradation and land subsidence caused by underground water resources in the studied area. In this way, by referring to the relevant organizations, such as the Iranian Water Resources Research Organization (Tamab), the regional water organization of Yazd and Kerman provinces, as well as previous researches, water quality parameters such as electrical conductivity, sodium absorption ratio, total dissolved solids and quantitative parameters water and subsidence rate were collected in the water year 2002-2018. The IMDPA model assessed the desertification situation in the Daranjir desert watershed using the two criteria of ground water and subsidence. In order to investigate the effect of subsidence and groundwater criteria on the intensity of desertification in the region, first the effect of two criteria of subsidence and the criterion of groundwater, and then by removing the criterion of subsidence, the intensity of desertification was evaluated only based on the criterion of groundwater. Geographic information systems and interpolation methods were utilized to zoning indicators and criteria.
Results: According to the electrical conductivity parameter zoning map, nearly 50% of the basin have a high salinity level (more than 5000 microsiemens percent), indicating a very severe level of desertification based on this index. Meanwhile, the zoning map of the sodium absorption ratio parameter showed that more than 50% of the basin's water resources have a low sodium absorption ratio (less than 18), which indicates the low expression intensity according to this index. According to this index, the intensity of desertification is indicated by the drop of more than 50 cm more than half of the basin observed during the investigation of the groundwater level drop. According to the IMDPA model groundwater criteria, the desertification situation was evaluated and found that over 50% of the basin surface had moderate intensity and almost 20% had severe status. Desertification intensity was highest in the ranges of Bahadran and Qoriya al-Arab, while it was lowest in the ranges of Qoriya al-Arab. Based on a subsidence map evaluation of three study areas (Kerman-Baghin, Rafsanjan, and Zarand), it was revealed that the the Kerman-Baghin area exhibits the highest subsidence rate between 12 and under seven cm.y. The evaluation of the desertification situation based on two criteria, subsidence and ground water in three areas with subsidence, showed that the Rafsanjan area has the highest intensity of desertification, according to two criteria.
Conclusion: In general, the results showed that the most important factor affecting the intensity of desertification according to the two criteria of groundwater and subsidence is the salinity of the groundwater and then the drop in the water level. Examining the areas with subsidence and the level of groundwater level drop in the study areas showed that in most cases, subsidence has occurred in the areas with a drop in the groundwater level. The assessment of the intensity of desertification according to the three water criteria parameters of the IMDPA model showed that desertification in the region has a low to very intense intensity. So that the middle class is included at the highest level in the watershed. Based on the percentage of the area of desertification intensity classes, after moderate intensity, areas with extreme intensity, low intensity, and very intense, respectively, are the highest level. The evaluation of the desertification situation by the study area showed that in Bahadran area, there are areas with a very severe state of desertification at a higher level than other study areas; this is despite the fact that desertification in the study areas of Saghand, Bardsir and Qoriya al-Arab only have two classes, low and moderate. The state of desertification based on the two criteria of "groundwater" and "subsidence" in three study areas with subsidence maps showed that desertification in the Rafsanjan area is more intense than the two areas of Zarand and Kerman-Baghin. To control desertification, it is recommended that water resource management includes monitoring groundwater extraction and utilizing optimal irrigation methods. Additionally, continuous monitoring and assessment of desertification status using the IMDPA model and oversight of water quality are essential. Developing vegetation through planting drought-resistant plants and implementing desertification projects will also be effective. Finally, raising awareness among farmers and the local community about sustainable agricultural practices is of great importance.
Materials and Methods: The desert watershed in Daranjir, located in the north of Kerman province and south of Yazd province, includes 12 study areas. The elevation ranges from 925 m in the Daranjir desert to 4465 m in the Kuh Hezar Mountain. The watershed covers an area of about 22,406 km2, while the deserts, salt marshes, plains, and foothills cover an area of 28,102 km2. The Daranjir desert, which measures 1000 km2, is deemed to be the end of the basin's surface and underground water drainage network. Groundwater data was utilized initially to investigate and study soil degradation and land subsidence caused by underground water resources in the studied area. In this way, by referring to the relevant organizations, such as the Iranian Water Resources Research Organization (Tamab), the regional water organization of Yazd and Kerman provinces, as well as previous researches, water quality parameters such as electrical conductivity, sodium absorption ratio, total dissolved solids and quantitative parameters water and subsidence rate were collected in the water year 2002-2018. The IMDPA model assessed the desertification situation in the Daranjir desert watershed using the two criteria of ground water and subsidence. In order to investigate the effect of subsidence and groundwater criteria on the intensity of desertification in the region, first the effect of two criteria of subsidence and the criterion of groundwater, and then by removing the criterion of subsidence, the intensity of desertification was evaluated only based on the criterion of groundwater. Geographic information systems and interpolation methods were utilized to zoning indicators and criteria.
Results: According to the electrical conductivity parameter zoning map, nearly 50% of the basin have a high salinity level (more than 5000 microsiemens percent), indicating a very severe level of desertification based on this index. Meanwhile, the zoning map of the sodium absorption ratio parameter showed that more than 50% of the basin's water resources have a low sodium absorption ratio (less than 18), which indicates the low expression intensity according to this index. According to this index, the intensity of desertification is indicated by the drop of more than 50 cm more than half of the basin observed during the investigation of the groundwater level drop. According to the IMDPA model groundwater criteria, the desertification situation was evaluated and found that over 50% of the basin surface had moderate intensity and almost 20% had severe status. Desertification intensity was highest in the ranges of Bahadran and Qoriya al-Arab, while it was lowest in the ranges of Qoriya al-Arab. Based on a subsidence map evaluation of three study areas (Kerman-Baghin, Rafsanjan, and Zarand), it was revealed that the the Kerman-Baghin area exhibits the highest subsidence rate between 12 and under seven cm.y. The evaluation of the desertification situation based on two criteria, subsidence and ground water in three areas with subsidence, showed that the Rafsanjan area has the highest intensity of desertification, according to two criteria.
Conclusion: In general, the results showed that the most important factor affecting the intensity of desertification according to the two criteria of groundwater and subsidence is the salinity of the groundwater and then the drop in the water level. Examining the areas with subsidence and the level of groundwater level drop in the study areas showed that in most cases, subsidence has occurred in the areas with a drop in the groundwater level. The assessment of the intensity of desertification according to the three water criteria parameters of the IMDPA model showed that desertification in the region has a low to very intense intensity. So that the middle class is included at the highest level in the watershed. Based on the percentage of the area of desertification intensity classes, after moderate intensity, areas with extreme intensity, low intensity, and very intense, respectively, are the highest level. The evaluation of the desertification situation by the study area showed that in Bahadran area, there are areas with a very severe state of desertification at a higher level than other study areas; this is despite the fact that desertification in the study areas of Saghand, Bardsir and Qoriya al-Arab only have two classes, low and moderate. The state of desertification based on the two criteria of "groundwater" and "subsidence" in three study areas with subsidence maps showed that desertification in the Rafsanjan area is more intense than the two areas of Zarand and Kerman-Baghin. To control desertification, it is recommended that water resource management includes monitoring groundwater extraction and utilizing optimal irrigation methods. Additionally, continuous monitoring and assessment of desertification status using the IMDPA model and oversight of water quality are essential. Developing vegetation through planting drought-resistant plants and implementing desertification projects will also be effective. Finally, raising awareness among farmers and the local community about sustainable agricultural practices is of great importance.
Type of Study: Research |
Subject:
فرسايش خاک و توليد رسوب
Received: 2024/10/20 | Accepted: 2025/03/14
Received: 2024/10/20 | Accepted: 2025/03/14
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