Evaluation of the Trend Changes in the Area covered by Construction and Demolition Wastes and its Effects on the Urban Environment (Case Study: Yazd City)

Construction and demolition waste is a special type of solid waste resulting from various construction, and renovation activities of residential buildings and infrastructures, and earth excavation, which is currently considered an emerging global crisis. The purpose of this research is to evaluate the changes in the area covered by construction waste for the last two decades (2002-2022) in the vicinity of Yazd city. To do this research, satellite images were analyzed for six four-year terms including 2002, 2006, 2010, 2014, 2018, and 2022. The results showed that C&D wastes has been abandoned all around the city, such as along the Yazd-Mehriz road, Yazd-Teft road, Gowde- Mahmoudi’s area, Shehneh village area, the playa of Yazd area, Kholdebarin area, Kouhestan Park area, and terminal area. Although, in the last decade, sites such as Kholdebarin, Shehneh village, Gowde-Mahmoudi, and the area of Kouhistan Park have been designated as C&D waste landfills and played an essential role in controlling the areas covered by construction debris, however, based on the results, the area under the construction waste has increased between 4 and 7 times in all the studied areas in the last 20 years. The most extensive of which is the site of the Shehneh village, which has increased from about 400,000 m^2  in 2002 to more than 1.2 〖km〗^2 in 2022. The unprincipled disposal of these wastes has not only given an ugly landscape to the city but also increased the risk of hazards such as floods, dust, air pollution, Pollution of water sources, soil pollution, and erosion. Thus, it requires a new management method, including recycling a large amount of them. Knowing the sites of waste disposal, the surface under cover, and the process of environmental changes affected by them is one of the fundamental measures of their management.
 
Extended Abstract
1-Introduction
Construction and demolition (C&D) waste is a special type of solid waste resulting from various construction, renovation, and demolition activities of residential buildings and infrastructures, and earth excavation. The increase in the population, increasing the level of well-being, and the continuous changes in patterns and lifestyles have caused a lot of construction, destruction, reconstruction, and renovation at present. Assessments show that the amount of this kind of solid waste is more than 25% of the total waste produced in the world and if a solution is not thought of today; Shortly, it will create bigger crises. The purpose of this research is to investigate and evaluate the changes in the area occupied by construction waste for the last two decades (2002-2022) in the vicinity of Yazd city, which, can be an opportunity for new solutions and management for this type of emerging waste.
 
2-Materials and Methods
This research has focused on the evaluation and study of the area covered by urban construction waste and their spatial changes in the last two decades. To do this research, satellite images were evaluated and analyzed for Six four-year terms including 2002, 2006, 2010, 2014, 2018, and 2022 as well as field observations. For this purpose, all parts and areas around the city of Yazd were investigated using satellite images and field observation. Preliminary observations showed that 10 sites, in the last 20 years, have been placed as C&D waste landfills including along the Yazd-Teft road, the Yazd-Mehriz road, Yazd Playa area, the Yazd University area, the Yazd Terminal area, and Khaldbarin area, Shehneh village, Goad-e-Mahmoudi area, and Kohistan Park area, which the last 4 sites of which are designated as permitted landfill’s site by the municipality. Therefore, the change trends of these ten sites in the last 20 years were evaluated using satellite images.
 
3- Results and Discussion
The results of the evaluation and analysis of satellite images showed that although at the beginning of the studied period, large areas of the surrounding regions of Yazd City were covered by construction waste, in the last 20 years, there has been a significant increase in all sites and surrounding areas of Yazd city. Based on the analysis of the images, the area under the cover of all construction waste, including legal and illegal sites, has increased between 4-7 times. According to the analysis of these images, the largest of them is the area of the village of Shehneh, which has increased from 400,000 square meters in 2002 to more than 1.2 square kilometers in 2022. Of course, the most widespread level of construction waste coverage is still affected by the distance from the city and access to construction landfill sites. For this reason, although in recent years, 4 sites of Khald-e-barin, Shehneh village, Gawd-e-Mahmoudi, and Kohestan Park have been designated by the municipality as legal sites of construction landfill, However, the largest increase in the area covered by construction waste around the city of Yazd has occurred in illegal areas, such as the playa area in the north of Yazd, the Tehran terminal area, along the roads from Yazd to Taft and Mehriz, which they show an increasing trend of more than 5 times in the last 20 years
 
4- Conclusion
The final results showed that a large volume of construction and demolition waste has been produced and abandoned in all adjacent areas of Yazd city in the past few decades, with the extensive development of the urban body as well as the renovation and reconstruction of public and private places in Yazd city. Unprincipled disposal of construction wastes has created many problems for the city of Yazd in terms of the environment, including the need for wide areas to bury them and creating an unsuitable landscape. Therefore, along all communication roads of Yazd City, inappropriate and ugly landscapes have been created due to the accumulation of C & D waste. In addition to the problem of the landscapes, the abandonment of a high volume of C & D waste within some dry rivers (channels) in the surroundings of Yazd City has caused both surface and underground water pollution. Besides, in times of floods, such as the flood of 2021 Yazd City, a large amount of destroyed materials from these construction wastes were washed away and returned to the city and entered the private and public spaces in the form of mud. Also, some of the chemical elements, present in these wastes, have entered the underground water cycle, which poses many risks to human societies, where these waters are currently abundantly used for drinking by the citizens of Yazd. Based on the results, which show the huge expansion of the area under the C & D waste in the vicinity of Yazd City in the last two decades, appropriate ways and methods of managing this type of waste are vital. According to global studies, the most important and basic method is the recycling of them. At least, these wastes can be used in the short term for some construction projects such as road construction, infrastructure, etc.