Infrequent seepage of rainwater causes flash flood: KMC's UIDD Chief Ram Thapa

The rivers in the valley are flooded whenever it rains because the rainwater cannot seep through the concrete infrastructures to fill the aquifer.

The incessant rain that occurred on Monday night till morning inundated at least 385 houses in Kathmandu Valley and waterlogged roads. The settlements near the rivers were affected by the inundation and floods. Although no human casualty was reported, 247 flood survivors were rescued. Whenever it rains in Kathmandu valley, the floods gushes into settlements close to the rivers. NepalNews talked to Engineer Ram Thapa, Kathmandu Metropolitan City's Urban Infrastructure Development Department (UIDD) Chief and Director, to gain some insight on the plan the KMC has developed to control the flash floods. Excerpts:

What are the causes of flooding rivers in Kathmandu valley?

Whenever it rains in Kathmandu valley, the settlements near the rivers get flooded or inundated. This is one of the challenges we have been facing owing to various factors. It has to be noted that the river channels in Kathmandu have been narrowed with the construction of roads on the banks of rivers — Bagmati, Bishnumati and Rudramati. The river beds which had once the width of 20 to 25 metres have been shrunk to 10 metres. Moreover, the wastes dumped at the rivers have also been found blocking the water flow. For instance, a few sections of rivulets in Samakhushi and Tukucha areas have been completely covered to conceal the unpleasant smell from the drainage connected to the rivers. But it creates another problem. The river should not be disturbed.

Why do rivers in the capital city get swollen suddenly whenever it rains?

The rivers in the valley are flooded whenever it rains because the rainwater cannot seep through the concrete infrastructures to fill the aquifer. As a result, the rainwater causes flash floods before flowing to the river. The seepage is very important for the balanced ecological system as it fills the aquifer and recharges the water sources underground. Due to infrequent seepage, the rainwater flows directly to the river and increases the water level.

Why is seepage of rainwater so important?

Apart from inundation and flash floods, the lack of seepage also creates a scarcity of water. For the population of 5 to 6 million in KMC alone, 50 to 70 million litres of water are not enough on weekly basis. It requires at least 320 million litres of water. And many households fetch water from underground. So, the recharge pits have to be built to enable the seepage to recharge the underground  water sources.

Has KMC initiated any campaign to raise public awareness of water bodies and systems?

The KMC has been leading the campaign for public awareness of water sources through the 'Recharge Kathmandu' programme. On the other hand, it has been made mandatory to plant at least two trees and a water recharge pit for every house to be constructed. Of the total 250,000 houses in KMC, if every house gets a recharge pit, half of the problem of flash flood and inundation will be solved.

What can be done to manage the settlements on the banks of the Bagmati and Bishnumati rivers?

As we now know that the floods and inundations are likely to occur near the river banks during the monsoon, the squatters occupying the riverbanks and others encroaching upon the water bodies are the issues to be resolved in social and political levels. The government will have to manage the settlements and prevent people from occupying such places. The rivers have to be cleaned from time to time to facilitate the smooth flow of water. The Urban Infrastructure Development Department has launched the river clean-up campaign. Recently, we have cleaned the Rudramati River, also known as Dhobikhola, in Anamnagar area.

High Powered Committee for Integrated Development of the Bagmati Civilisation is responsible to decide on the construction of infrastructures near rivers. The KMC alone cannot deal with it, and floods and inundation cannot be prevented immediately. It will take some time.

What do you say about the infrastructures being constructed near rivers?

The rivers should not be disturbed by any infrastructures. The construction of bridges over the rivers should be inspected whether it is up to the standard. Many bridges have been built too low that disturb the flow of swollen rivers during the monsoon. The sectors and stakeholders concerned should also ensure the construction of proper embankments on the edge of rivers.