Understanding Sinkholes in Urban Areas: Causes, Current Measures, and Future Steps

Introduction

Sinkholes are a growing concern in many urban areas worldwide, and the recent incident in Kuala Lumpur, where a tourist from India fell into a sinkhole near Jalan Masjid India, has brought this issue into sharp focus. This tragic event has highlighted the need for a better understanding of sinkholes, their causes, and the steps necessary to prevent them, especially in densely populated cities.

What Are Sinkholes?

A sinkhole is a depression or hole in the ground caused by the collapse of a surface layer into an underlying void. These formations can appear suddenly or develop gradually, depending on the conditions underground. While sinkholes can occur naturally, they are often exacerbated by human activities, particularly in urban environments.

Causes of Sinkholes

1. Natural Processes:

- Erosion and Weathering: Over time, the dissolution of soluble rocks (such as limestone, gypsum, or salt beds) by water creates underground cavities. When these cavities grow large enough, the surface layer may collapse into them, forming a sinkhole.

- Fluctuations in Groundwater Levels: Changes in the water table, due to natural events like heavy rainfall or drought, can also contribute to sinkhole formation. For instance, a rapid drop in the water table can leave underground cavities unsupported, leading to a collapse.

2. Human Activities:

- Construction and Drilling: Urban development often involves significant alterations to the landscape, including construction, drilling, and tunneling, which can destabilize the ground and contribute to sinkhole formation.

- Excessive Groundwater Extraction: Over-pumping groundwater for industrial, agricultural, or municipal use can lower the water table, increasing the risk of sinkholes.

- Leaking Pipes: In urban areas, leaks from underground water or sewer pipes can erode the soil and rock beneath the surface. Over time, this erosion weakens the ground, making it more susceptible to collapse.

The Recent Incident in Kuala Lumpur

On August 23, 2024, a 48-year-old Indian tourist, Vijayaletchumy, was walking near Jalan Masjid India in Kuala Lumpur when a section of the sidewalk caved in, leaving an eight-meter-deep sinkhole. The incident, which occurred around 8 am, triggered a swift response from the Kuala Lumpur City Hall (DBKL) and other emergency services, including a search and rescue operation involving 200 personnel from DBKL, the police, and the Fire and Rescue Department.

This incident, while isolated, has raised urgent questions about the safety and maintenance of urban infrastructure, especially in areas with high pedestrian traffic.

Current Measures by DBKL

Following the incident, DBKL and other city authorities have been urged to take immediate steps to prevent future occurrences:

1. Inspection of Drainage and Sewerage Systems:

- As highlighted by Bukit Bintang MP Fong Kui Lun, a thorough inspection of the city's drainage and sewerage systems is crucial. Leaks or blockages in these systems can lead to soil erosion, which may cause sinkholes.

- Regular maintenance and prompt repair of any identified issues are necessary to ensure the integrity of these systems.

2. Utility Mapping and Collaboration:

- Communications Minister Fahmi Fadzil has emphasized the importance of accurate underground utility mapping. Many areas contain pipelines and electric cables that are not always accurately represented on maps, increasing the risk of accidental damage during construction or maintenance work.

- A collaborative approach between DBKL, utility companies, and other relevant agencies is essential to create a comprehensive underground utility map. This would help prevent incidents caused by unknown or inaccurately mapped underground infrastructure.

3. Updating Standard Operating Procedures (SOPs):

- DBKL has been called upon to revise its SOPs to address both sinkholes and related issues such as flash floods. Ensuring that SOPs are up-to-date and include provisions for rapid response to sinkholes is vital for public safety.

Future Improvements for Urban Sinkhole Prevention

To mitigate the risk of sinkholes and enhance urban safety, several long-term strategies should be implemented:

1. Advanced Geotechnical Surveys:

- Incorporating advanced geotechnical surveys into urban planning and construction projects can help identify areas at risk of sinkhole formation. Techniques such as ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) can detect underground voids and weak zones before they lead to surface collapses.

2. Improved Groundwater Management:

- Implementing better groundwater management practices is essential, particularly in cities where excessive groundwater extraction is a concern. Regulations that limit groundwater withdrawal and promote sustainable usage can help maintain stable underground conditions.

3. Infrastructure Modernization:

- Modernizing aging infrastructure, including water and sewer pipes, is crucial to prevent leaks that can erode underground materials. Utilizing durable materials and construction techniques that minimize ground disturbance can reduce the risk of sinkholes.

4. Public Awareness and Education:

- Raising public awareness about the signs of potential sinkhole development and the importance of reporting ground subsidence or unusual surface cracks can help authorities respond more quickly to emerging threats.

5. Regular Monitoring and Maintenance:

- Establishing a routine monitoring and maintenance schedule for key infrastructure components, such as sidewalks, roadways, and underground utilities, can help identify vulnerabilities before they lead to significant incidents. This proactive approach should include using technology like GIS (Geographic Information Systems) to map and track infrastructure conditions over time.

6. Enhanced Emergency Response Preparedness:

- Strengthening emergency response protocols to ensure a quick and coordinated response to sinkhole incidents is crucial. Training emergency personnel and conducting regular drills can help improve preparedness and minimize the impact of future events.

Conclusion

The recent sinkhole incident in Kuala Lumpur serves as a stark reminder of the vulnerabilities present in urban environments. By understanding the causes of sinkholes and implementing comprehensive preventive measures, city authorities can better protect residents and visitors alike. A combination of modern technology, sustainable practices, and community engagement is essential to minimize the risks associated with sinkholes and ensure safer urban living spaces.

References:

1) DBKL urged to check drainage, sewerage systems after Masjid India sidewalk collapse | The Star

2) Accurate underground mapping a necessity, Fahmi tells DBKL, utility companies after Masjid India sinkhole | Malay Mail

3) DBKL: Here’s a quick look at how and why sinkholes appear, after a KL pavement swallowed a tourist from India | Sinkhole | Head Topics

4) Sinkholes: Engineering Solutions for Prevention and Remediation | MFS Engineering (mfsengineers.com)

5) National Preparedness Month 2020: Landslides and Sinkholes | U.S. Geological Survey (usgs.gov)

6) How to Prevent Sinkholes: 10 Steps (with Pictures) - wikiHow

7) Sinkholes | U.S. Geological Survey (usgs.gov)

8) Sinkholes | UN-SPIDER Knowledge Portal

9) (PDF) GIS based AHP Technique for Sinkhole Susceptibility Hazard Zones: Case Study under DBKL & MPAJ | Muhamad Arief - Academia.edu