Shahrin Tabassum
We are faced with various types of natural disasters in our daily lives that are floods, cyclones, droughts, earthquakes, salinity. A new natural disaster is a sinkhole, which is seen in Turkey, Israel, and even neighboring countries India at a massive rate nowadays.
A sinkhole is a hole formed by the sudden or gradual collapse of land in a place. Groundwater extracting or excessive lifting of rocks and minerals results in sinkholes. These usually range from a few feet to several hundred acres and may have a depth of 1 to 2000 feet. These look a lot like shallow bowls or kitchen sinks. In some sinkholes when water accumulates, ponds are made naturally. According to experts, global warming and climate change are direct the sinkholes are being made by effects. These holes are becoming visible in many countries of the world. Again in some countries, more than 300 sinkholes are completely natural. It takes decades even centuries to create a sinkhole. Recently its rate has increased drastically.
Scientists blame the excessive extraction of groundwater and minerals for the increase in the number of sinkholes. Sinkholes are usually formed by two processes: (1) From the chemical breakdown of various ore rocks and (2) The suffosion process where water or any other liquid causes groundwater or rocks to evaporate. A sinkhole is a hole in nature formed suddenly. When it rains, the surface water is filtered and stored in the soil subsoil which we call aquifer. The water stored in this aquifer is used for various purposes such as irrigation, drinking, household chores, etc. We lift this water with the help of machines. Sometimes we extract more water than our needs. In many cases, we waste the extra water. This lifting creates inconsistencies in the ground and creates gaps. Then a large hole fell on the surface is created.
Geologists say that not only water extraction but also the removal of hard rock inside the soil is increasing the number of sinkholes. In areas where there is hard rock in the soil, the rate of extraction is higher. There are salts and mineral layers like limestone, copper, and gypsum in there. Unplanned and excessive extraction of these minerals results in soil hollow spaces inside. Then the soil surface of the area collapsed under its weight and made a sinkhole. Also due to global warming, severe erosion, soil erosion, falling water levels, effects of methane gas, etc., sinkholes are made. Unplanned underground sewerage lines or underground constructions are referred to as the cause of sinkhole growth in the city. The work is being taken over. Although sinkholes are thought to be landslides, they are two completely different natural forms.
Sinkholes are not a new disaster in nature. However, geologists are worried that the hole will be made in five countries within a month has done. Turkey, a Middle Eastern country, is one of the biggest concerns about the recent sinkholes. Most so far in the country, more sinkholes have been seen. In 2020, the number of sinkholes there was 360, now it has increased to 600. The country’s water management policy is being blamed for this. For wheat cultivation, due to 10-15 years of drought farmers have to depend on groundwater as irrigation water. Where previously there was drought, farmers irrigated twice a year but now they have to irrigate five to six times a year. As a result of lifting billions of liters of water, the water level went down and giant holes are being made. If this situation persists, Turkey is heading for another epidemic in the innumerable sinkholes. Yes, there will be extreme famine.
Apart from Turkey, sinkholes are widespread in many other countries of the world. The largest natural sinkhole in the world is in Egypt located in Cairo, it is 133 m deep, 60 km long, and 120 km wide. 2690 feet deep sinkhole located in Chile, Chukuichamata was created in 1910. The Xiaojai Tiankeng sinkhole in Chongqing, China, is 62 meters deep and 628 meters wide. There are sinkholes in Siberia covering an area of 1 km. In Croatia after an earthquake, more than a hundred sinkholes have been created. It has also been made in Italy, Mexico, Israel, and even India.
In many cases, the sinkholes do not form suddenly. It takes many months and even years. Again in some cases, the holes were seen to be formed without any prior signal. Researchers are working day and night to find the real culprits. The goal is to gain a thorough understanding of structure, nature, and etymology. Change is visible in the place of sinkholes. A sign can be seen of a deep sinkhole forming cracks in the foundation of a building or house or inside a house, cracks in the ground. Even if it occurs, appropriate steps should be taken. Even if the plants die, dry up, or suddenly fall to the ground sinkholes may be created there. Water and other elements are removed from the sinkhole area thus trees of the area can’t live. Also, be careful even if the water in the tubewell or tap is suddenly opaque or the turbidity is high. Because of the different minerals with the dissolution of soil and water this opaque or turbid water is formed. In many cases after the appearance of a circle on the ground within a few minutes to a few hours, a place can turn into a sinkhole. As a result, many have to face adversity which is not desirable at all.
Natural sinkholes cannot be prevented. For example, layers made of limestone or gypsum are easily absorbed into the water. As a result, the layers become thinner and sink to the ground as they cannot carry the load on top. Of this structure, sinkholes are naturally formed and are irresistible. Some holes are also made by humans. As a result of excessive extraction of groundwater, the water level goes down and accelerates the formation of holes. Special attention should be paid to raising the water level and recharging the groundwater table. Unnecessary wastage of water should be reduced. Everyone should follow the proper rules of resistance to drought and must continue. In many cases, it is seen that the holes made are used for dumping waste or dirt which is not desirable at all. This is because leachate or water made from dirt often contaminates the water by mixing with the groundwater level. In this manner, diseases are caused by germs entering the human body. So the sinkholes are not littered in any way and cannot be used for dumping.
In agricultural Bangladesh, 7.5 meters of water is taken annually. Of which 5.5 meters comes from the surface of the earth and the remaining 2 meters is from rainwater. Thus, groundwater is used extensively for irrigation in agriculture and more is wasted than used. As a result, the water level has dropped to more than 6 meters and in that place, high-density marine saline water is taking its place. If such a situation continues, there will be a disaster like a sinkhole in Bangladesh. Earthquakes are now becoming very common in the country. Earthquakes are largely responsible due to the increase in the number of sinkholes. Extreme disasters can create a sinkhole for a developing country like Bangladesh. So all of us must be aware and the level of groundwater extraction must be reduced. Towards groundwater table recharge special attention should be paid. Only then will it be possible to get rid of the disaster called a sinkhole.
Author is a Student of Environmental Science and Engineering at Jatiya Kabi Kazi Nazrul Islam University, Trishal, Mymensingh-2224, Bangladesh. Email: shahrin5792@gmail.com
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