An Explanation of the Impact of Changes in climate elements on the land use changes in the Karoon River Basin

Precipitation and temperature are important elements of climate. Changes in these elements can have a significant impact on the changes in other environmental components, including changes in land use. This study aimed to investigate the long-term changes in temperature and precipitation in the Karun basin. Then the probable relationship between these changes and land use changes was investigated. Therefore, the daily temperature and precipitation data from 177 synoptic stations and 230 rain gauge stations were prepared from 1972 to 2014. Daily maps were made up of 4 x 4 km, using the kriging interpolation method. Due to the climatic and spatial diversity of the Karun, the basin was divided into 12 smaller sub-basins. Using google earth engine (GEE) and using the digital data of Landsat 5, 7, and 8 series satellites, TM, and OLI/TIRS sensors, land use maps were extracted by calculating the mean of each use. For the classification of images, the algorithm of the minimum distance from the mean was used for several years (1987 - 1997 - 2007-2018). To monitor the temporal changes in land use, the dynamic model of land use was also used. The results of the research showed that in the high basins of Karun, the variation in the climatic elements played a significant role in land use changes. In the sub-basins of Karon, the decrease in rainfall over time has had a destructive effect on the degradation of forests, pastures, water levels, and water agriculture in the region. So that in recent years, the amount of destruction of forests and pastures has reached its peak and it is mostly dedicated to aquatic cultivation. The drilling of deep and semi-deep wells and the unprincipled exploitation of the underground water have also caused that over time, Karun faces surface and underground water crises and as a result many economic, agricultural, and social crises.Using google earth engine (GEE) and landsat 5,7,8 images, land use maps were produced. For classification of images, the algorithm minimum distance of mean was used for years of 1987 - 1997 - 2007. In order to monitoring changes of land use, land use dynamics model was used. The results showed that in the Karun basin, the variation of climate elements has a significant role in land use changes. In the Karun, precipitation reduction had negative effects on the degradation of forests, pastures, water levels and aquatic agriculture. So, the destruction of forests and pastures has been increased. The Welles and exploiting the groundwater led the Karun into the surface of the surface and underground water crisis. Extended Abstract Introduction The increasing world population, greenhouse gases emission, and land use changes through dam construction, deforestation, desertification, etc., have caused changes in the climate system. These changes can be effective along with positive feedback on the natural ecosystems and the activity of human societies. Precipitation and temperature are important elements of climate. Precipitation and air temperature are important elements of climate. The change of these two elements can have a significant impact on the changes of other environmental components, including changes in land use. In this study, the temperature and precipitation trend in the Karun basin has been investigated. Then, the possible relation among these changes, temperature, and precipitation was evaluated by examining the decade-long changes in land use.MethodologyTo achieve the objectives of the research, two types of data including ground data and satellite data were used. GEE system was used to monitor land use changes on the surface of the earth using Landsat satellite images. Also, Kendall's test was used to identify the trend of climatic elements. To detect the land use changes, the classification algorithm of minimum distance from the mean was used. Using the dynamic model, the changes in the time series of users were evaluated.Results and discussionThe fluctuations and multiple collisions of Mann-Kendall diagrams showed that precipitation has varying behavior. Changes can be seen in mountain basins such as sub-basins 2, 3, and 4. As the height decreases, the amount of fluctuations is significantly reduced. This shows that height has an influential role in the rainfall changes in the region. The results of classification showed that considerable variation has occurred in subbasins land use. Most changes have been related to changes in water levels, arid regions, and forests. The impact of human activity, including afforestation and the development of hydroponics, the conversion of pastures into agricultural lands, increases the risk of floods, fires, soil erosion, and the entry of polluting substances into water sources.ConclusionIn the Karun basin, the decrease in rainfall over time has had a destructive effect on the reduction of forests, pastures, water levels and water agriculture in the region. So that during the last decade, the amount of destruction of forests and pastures has reached its peak and more is devoted to dryland farming. Also, the occurrence of these changes has led to an increase in the extent of arid areas in the region over time and has reached the maximum possible extent in recent years. In the Karun basin, taking into account that the area under cultivation of irrigated crops has increased and the amount of water in the region has decreased over time, it can be expected that the huge amount of water demand for irrigated cultivation and the lack of water will lead to water stress in the future. The increase in cultivation areas has been in line with the destruction of forests to be used in the agricultural sector. Therefore, from year to year, the extent of forests in the Karun region has decreased.Funding There is no funding support.Authors’ Contribution The authors contribute equally to the conceptualization and writing of the article. All authors approved the content of the article submitted for review and agree on all aspects of the work.Conflict of Interest Authors declared no conflict of interest.Acknowledgments We are grateful to all the persons for scientific consulting in this paper.