Simulation of land-use changes in the suburbs of Zahedan

Abstract
Introduction
More than half of the world's population now lives in cities. The most important spatial manifestation of urban population growth is the physical growth of cities. Many surrounding villages have been integrated into the physical fabric of cities, which has led to marginalization, destruction of agricultural lands and the fragmentation of the physical fabric city. Today, land use change is accelerating along with the rapid growth of urban land and has an important role in urban land use changes. Therefore, land use change is a process during which human activities change the natural landscape .Since land use change is considered as irreversible change, access to up-to-date statistics and information and awareness of the change process are important factors in planning and decision making. In this part, land use maps that show the current conditions and how to use the land are important. The scattered and widespread trend of Zahedan city in the last hundred years needs to be studied and monitored. The aim of this study is to investigate the trend and predict land use changes in Zahedan city using satellite images and Markov chain model in the years 2000 to 2040.
Methodology
This research is descriptive and analytical in nature and quantitative in terms of methodology. In this research, the images of ETM sensor, Landsat 7 related to 2000 and 2010 and Operational Land Imager (OLI) Landsat 8 satellite in 2021 have been used .satellite imagery data with 30 m resolution for 17 July 2000, 13 July 2010 and 16 May 2021 were downloaded from the US Geological Survey.
Then, data were prepared for analysis using ArcGIS and TerrSet software. Subsequently, samples of land use were digitized into four classes using the Digitize option in TerrSet software. After that, digitized land uses were categorized into four classes in TerrSet using Maximum Likelihood Estimation. The quality and usability of classified images of 2000, 2010 and 2021 were estimated by accuracy assessment Then, Land Change Modeller was used to predict land use changes from 2021–2040.
Conclusion
The concentration of more than half of the world's population in urban areas by 2021 and the multiplication of urban land growth have made land use change an environmental challenge. This study was conducted to investigate land use change in Zahedan. What further emphasizes the need to analyze land use change and predict its future is the development of the surrounding city, outside the process of comprehensive planning and suburbanization, which is a serious threat to agricultural land.For this purpose, land use change study was performed in three periods of 2000, 2010 and 2021 and four floors using Landsat 7, 8 satellite images with a resolution of 30 meters and Markov chain model. Finally, based on the results, future land use change for 2021 to 2040 was predicted in ArcGIS and TerrSet. The forecast result was compared with the 2021 map to validate the evaluation method using kappa index statistics. The result of kappa coefficient (85%) was acceptable. Findings show that among the four land use categories, during the period 2021-2000 in the study area, 4049 hectares of land use (including built-up area and agricultural lands) occurred, which is equal to about 202.4 hectares in Is the year. The largest increase in land use in barren lands, 6154 hectares (26.8%) and then built areas, 3875 hectares (93.19%) in the same period and the largest decrease in land related to grassland and agricultural lands 174 hectares (-26.6%). It is predicted (2021-2040) in the study area of 1546 hectares of land use change, equal to 81.3 hectares per year. During this period, the construction area increased to 571 hectares (7.1%) and grassland to 4 hectares ((9. 72%) and gardens and agricultural land to 11 hectares (-2.3%) and barren lands to 960 hectares (-7 / 5%) is reduced. It seems that according to the forecast of the comprehensive plan of Zahedan city during the three periods of 64, 84 and 94 and determining the directions of city development, there are no special requirements for controlling the development of the city by managers. Because the increase in population and the expansion of suburbanization in the northeast of the city has led to the destruction of agricultural land and irresponsible development and resulting from the rent of government organizations involved in urban management has led to a kind of scattered surface in the lands around the city.
Keywords :Land use change, city development, Landsat, Markov chain, Zahedan
Results and discussion
By analyzing land-use change not only in the past and present, but also for predicting the future, The extent of expansion and destruction of resources can be determined by identifying appropriate land use patterns and directing possible changes in the right direction. Therefore, urban growth simulation can provide a better understanding of the future effects of land use policies. Accordingly, land use change in the city of Zahedan with an area of 85 square kilometers, was measured using Landsat 7.8 and LOI for 2000, 2010 and 2021 in TerrSet and GIS software. Then, these changes until 2040 were predicted using the Markov chain. The results of land use changes for the period 2021-2000 show an increase of 93.2% in residential lands and a decrease (- 26.6%) in orchards and agricultural lands. Given that the population growth rate shows a decrease in the years 2000 to 2021. But the population growth index in the form of urban development occurred to the outer regions. Slums make up about 42% of the total population of the city and this is a serious threat to agricultural land in the northeastern part of the city.