Evaluation of active geomorphodynamics in the territory of Iran using advanced satellite radar interference techniques

Geographical extent, increasing intensity and the trend of adding new areas are the challenges of researchers and managers in the face of subsidence crisis due to the withdrawal of groundwater resources in Iran. To these challenges must be added secondary crises such as social, security, food and health consequences. In this regard, the importance of continuous and accurate monitoring in the first stage and then zoning of critical areas is the first step in creating a roadmap for land management and control and confrontation of subsidence crisis. In this study, the entire area of ​​Iran enclosed on the Iranian plateau was examined using 132 data frames of Sentinel-1 radar satellites at C-Band wavelength. This study was conducted to discover the amount of vertical surface displacement and its relationship with groundwater abstraction in the period between 2015 and 2017. After measuring the subsidence rate in the plains, in order to zoning the areas, three classes (1) subsidence up to 0.5 cm per month, (2) subsidence from 0.5 to 1 cm per month and (3) subsidence at more than 1 cm per month was introduced. The results showed that an area of ​​28,000 square kilometers of Iranian plains has subsidence. About 7% of these plains, with an area of ​​1,900 square kilometers, suffer at least 12 cm of subsidence annually. On the other hand, about 22% of the plains with an area of ​​about 6,100 square kilometers experience subsidence between 6 and 12 cm per year. However, most of these landslides occurred in an area of ​​20,000 square kilometers, which accounts for 71% of the total area of ​​these plains. The minimum subsidence rate in these areas is 6 cm per year, which is a worrying situation due to its size, amplitude and severity. The results show that 14 provincial capitals and 110 cities are currently either submerged or exposed to it. One of the critical areas is Kashmar plain with a rate of subsidence in the country with a rate of more than 2 cm per month. Akbarabad plains in the south of Shiraz, Rizab plain in the east of Fars province and Shahrmian and Mahdiabad plains in the west of Fars province, Bardsir and Aliabad plains as well as all southern regions of Jiroft including Faryab and Kahnooj plains in Kerman province and Golpayegan plain in Isfahan province were named. In the end, it was suggested that using methods such as (1) continuous field and satellite monitoring (2) accurate measurement of land movement by constructing GNSS stations (3) continuous monitoring in subsidence plains and also (4) dismantling of illegal wells and (5) Monitoring the harvesting of authorized wells, (6) changing the pattern of agriculture and irrigation, and (7) stopping the cultivation of some crops that have high water consumption per capita from the crop calendar, can not exacerbate the current trend of this crisis in the short and long term. . Also, since land subsidence is an irreparable phenomenon even if the groundwater resources increase in the future, it is necessary to draw a roadmap by the Program and Budget Organization and its responsible institutions in the next few decades. The severity of this crisis has diminished.