Flood risk downstream has eased after water began gradually flowing through the Hunga Khola in Solukhumbu, where a landslide had blocked the river and formed a natural dam on Friday morning.

The landslide occurred between wards 2 and 4 of Mahakulung Rural Municipality at around 7 am, creating a roughly 100-metre-long blockage. Water began flowing through the dam about three hours later.

Tubaraj Pokhrel, chief district officer of neighbouring Okhaldhunga, said the risk appeared to be declining as water gradually began spilling from the upper section of the lake formed behind the landslide.

Authorities had been concerned that a sudden breach of the dam could send a flash flood downstream, threatening settlements and infrastructure along the river. The administrations of Solukhumbu, Okhaldhunga and Udayapur had alerted residents in potentially affected areas.

In the event of a sudden breach, settlements and infrastructure along the river in lower Solukhumbu and around the Jairamghat area of Okhaldhunga were considered at risk. Nepal Police and the Armed Police Force used public-address systems to warn residents in vulnerable areas to remain alert and move to safer locations if flooding occurred.

A breach could have sent floodwaters through Sotang and Thulung Dudhkoshi rural municipalities in Solukhumbu before reaching the Dudhkoshi River at Jairamghat in Okhaldhunga. The floodwaters could then have affected seven local government areas in Udayapur after entering the Koshi River.

Udayapur District Administration Office issued an alert soon after learning of the blockage.

Mekha Bahadur Mongrati, chief district officer of Udayapur, said residents along the riverbanks had been warned, taking into account the potential for flooding to reach the Ghurmi area of Katari Municipality first, followed by areas of Tapli, Limchungbung and Rautamai rural municipalities, and then Belaka and Chaudandigadhi municipalities.

But the situation has since improved.

“The water from the dam is now flowing normally, so the water levels in the Dudhkoshi, Sunkoshi and Saptakoshi rivers have only risen,” Mongrati said. “There is no immediate risk, and there is no need to evacuate settlements at this point.”