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During heavy rainfall, particularly during the monsoon season, drains along the stretch from Changzamtog school to NoNo Furniture shop in Thimphu tend to overflow as increased surface runoff puts additional pressure on the existing drainage system.
The overflow can result in water accumulating along roadsides and low-lying areas, affecting pedestrians, motorists and nearby businesses. The situation is also worsened when rainwater carries soil, leaves and other debris into the drains, restricting the flow of water and causing blockages at certain points.
As the area has seen increased movement of vehicles and pedestrians, effective drainage is important to prevent rainwater from remaining on the roads and surrounding areas. Regular cleaning and maintenance of the drains, along with improvements to sections where water flow is inadequate, could help reduce the risk of overflow during heavy rainfall.
According to the Chief of the Infrastructure Division of Thimphu Thromde, Ngawang, the drainage system does not face any significant problems under normal conditions. However, during heavy rainfall, particularly during the monsoon season, the drains tend to overflow due to increased surface runoff. He said illegal disposal of waste into the drains is another major factor contributing to the problem. Waste dumped into the drainage system can obstruct the flow of water and increase the likelihood of overflow during periods of heavy rainfall.
Ngawang said no new construction or major development of the drainage system has been carried out in the area over the past three years. However, he said plans are in place to improve and develop the drainage system under the second phase of the Low Emission Transport Master Plan (LETMP).
The drainage overflow also affects shopkeepers operating along the stretch, particularly those who display vegetables and other fresh produce outside their shops. During heavy rainfall, vehicles passing through the area can splash water from the roadside onto the produce, affecting its cleanliness and quality. Shopkeepers are concerned that repeated splashing of dirty rainwater can make the vegetables unattractive to customers and may result in losses if the produce becomes contaminated or damaged.
They say better drainage and proper management of surface runoff could help reduce water accumulation along the roadside and minimize the impact on businesses during the monsoon season.
Thimphu Thromde has developed a Stormwater Drainage Master Plan to guide the development and improvement of stormwater drainage infrastructure across the city. According to Ngawang, the Thromde will follow the provisions of the master plan as new projects are undertaken. Drainage systems will be constructed or upgraded based on the plan to increase drainage capacity and reduce the risk of waterlogging and overflow.
He said the master plan will provide a framework for addressing drainage requirements as the city develops and help ensure that future infrastructure projects take stormwater management into consideration.
The plan is expected to guide the Thromde in improving drainage capacity and addressing areas vulnerable to waterlogging and overflow.
