Tuesday Aug 9, 2022
Tuesday Aug 9, 2022

Urbanization, monsoon and poor drainage causing flash floods in Kathmandu

Waterlogging and urban floods have become common in Kathmandu valley since the start of monsoon, which all comes down to the mismanaged and badly designed drainage system.


Nepalnews
2022 Jul 04, 6:22, Kathmandu
A man having trouble moving Jars of water in muddy road at Hiledole, Kathmandu. Photo: Prasan Gurung/Nepalnews

The rapid and unplanned urbanization of Kathmandu Valley has brought negative impacts to its overall development. However, the issues of drainage management have always been a major problem in Kathmandu along with other various urban areas of Nepal.

The urban growth rate of Kathmandu is nearly 6.5 percent every year, with one of the highest population densities in the world, which has resulted in congested and crowded roads, encroached rivulets, concretization of the city and road junctions becoming a garbage dumping site. Unplanned urbanization and the lack of sustainable infrastructure planning has led to Kathmandu experiencing regular flash floods in recent years.

“The drainage system of Kathmandu is severely mismanaged, and badly designed. With the rising population and urbanization, the drainage system is unable to take the pressure. Even if it rains lightly, roads and houses in Kathmandu get flooded nowadays. With the monsoon at its peak the situation is likely to get worse. Urbanization has occurred at a constant pace in Kathmandu for the last ten years yet the drainage system remains the same. Traditional drainage does not have the capacity to contain the increased level of water flow and thus flash floods have become a regular occurrence,” said Sanot Adhikari, environmentalist and chairperson of Youth Alliance for Environment (YAE), an NGO that is dedicated to establish the environmental issues in society and enhance the capacity of young researchers and environmental graduates.


Rapid concretization: drying groundwater resources and causing flash floods across the valley.
Rapid concretization: drying groundwater resources and causing flash floods across the valley.

According to experts of hydrogeology, with an increasing concrete cover in Kathmandu Valley, urban floods have become a common occurrence in residential areas. In September 2021, Kathmandu Valley alone recorded 121.5 mm of rain on a single night, causing massive floods in various areas of the valley. Such floods exponentially expose poor urban planning, bad development strategies and encroachment of rivulets that is caused by haphazard build infrastructure near river areas.

A study also finds that the effects of monsoon rain on ground water is limited only to agricultural land in the valley. Groundwater recharge is limited in areas with concrete built-up in Kathmandu. The built-up area is projected to increase by 21 percent between 2020 and 2050, predicting a significant implication for further groundwater depletion. According to experts, there is no coordination between various government agencies while planning the city’s infrastructure even though there is a common realization that groundwater needs preservation, particularly in Kathmandu, which has a small watershed .


The increased rate of rain precipitation making the traditional drainage unable to cope with the pressure of water, leading to waterlogged roads and floods.
The increased rate of rain precipitation making the traditional drainage unable to cope with the pressure of water, leading to waterlogged roads and floods.

Adhikari further emphasized that in the last 20 to 30 years, open agricultural land has been extensively concretized. Thus, concrete buildings and blacktopped roads stop infiltration of rain in soil, causing dirty rain water to flow to the river polluting the water resources while many ponds go dry. “As water fails to enter the soil due to concrete houses and paved roads and the sewerage gets jammed due to litter, even light rains could cause spread of water on the streets in the capital city. There is also a decline in underground water and increase in urban flooding.” Adhikari added.

Climate change is also one of the major factors affecting the drainage system negatively. Rainfall has intensified over the years and the weather pattern has also changed. A report released by the Intergovernmental Panel on Climate Change, the world’s leading authority on climate science, talks about climate change impacts in South Asia, projecting not only extreme precipitation but also river floods across the region.

“While planning to build infrastructures, many urban planners do not consider the changing environment and climate. The precipitation index has also increased in very less time. But infrastructures are developed without any care of the future needs and such estimations. Unsustainable development programs fail to maximize the capacity of the present drainage system”, added Adhikari. He also explained how poorly managed drainage can mix with sewage due to leakages causing hazardous impacts on both humans and the environment.


Climate change adversely triggering floods around Nepal, which must be taken into notice while building new infrastructures. Photo- UNESCO
Climate change adversely triggering floods around Nepal, which must be taken into notice while building new infrastructures. Photo- UNESCO

Flash floods in Kathmandu have become frequent and locals have expressed deep dissatisfaction with the poor management of drainage in recent years. Some areas are receiving more rainfall than previous years this monsoon, which poses a great risk to human lives and properties. With the onset of monsoon, pictures of Kathmandu streets being waterlogged have started to resurface on social media and locals have now started to plan ahead for the onslaught of flash floods.

“Flash floods and waterlogged roads cause traffic to get blocked for a long time. The roads get slippery and cause many accidents”, said Ram Bahadur Gurung, a local resident of Panipokhari, Kathmandu. He further added, “Due to frequent delay in garbage collection, rain water also flows along with garbage into rivers, it mixes with drinking water and causes diseases and epidemics to arise, like cholera in recent times. The smell is also horrific. It not only causes water pollution but also air and land pollution.”

Although urbanization is an inevitable process, the government needs to allocate new spaces for urban infrastructure around the potential routes in a much wider area covering multiple districts connected to Kathmandu, which can stop further concretization of the valley. The government can also plan on collaborative agriculture based programs that can introduce urban agriculture in the Valley. While houses and infrastructures built near rivers need to be shifted elsewhere, which can put a stop to encroachment of rivulets. Citizens of the valley should also be trained and encouraged to harvest rainwater.


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