Aerial photo taken on July 21, 2020 shows the flood-stricken area in Qilihe District of Lanzhou, northwest China's Gansu Province. The Lanzhou hydrological station of the Yellow River saw the second flood of the river this year with the water flow of 3,000 cubic meters per second, which occured at 8:42 p.m. on Monday. (Xinhua/Fan Peishen)

Aerial photo taken on July 21, 2020 shows a flood-stricken dock in Qilihe District of Lanzhou, northwest China's Gansu Province. The Lanzhou hydrological station of the Yellow River saw the second flood of the river this year with the water flow of 3,000 cubic meters per second, which occured at 8:42 p.m. on Monday. (Xinhua/Fan Peishen)

Aerial photo taken on July 21, 2020 shows a flood-stricken park in Qilihe District of Lanzhou, northwest China's Gansu Province. The Lanzhou hydrological station of the Yellow River saw the second flood of the river this year with the water flow of 3,000 cubic meters per second, which occured at 8:42 p.m. on Monday. (Xinhua/Fan Peishen)

Aerial photo taken on July 21, 2020 shows a view of the Lanzhou section of the Yellow River in Chengguan District of Lanzhou, northwest China's Gansu Province. The Lanzhou hydrological station of the Yellow River saw the second flood of the river this year with the water flow of 3,000 cubic meters per second, which occured at 8:42 p.m. on Monday. (Xinhua/Fan Peishen)

Aerial photo taken on July 21, 2020 shows a dock submerged by floodwater along the Lanzhou section of the Yellow River in Chengguan District of Lanzhou, northwest China's Gansu Province. The Lanzhou hydrological station of the Yellow River saw the second flood of the river this year with the water flow of 3,000 cubic meters per second, which occured at 8:42 p.m. on Monday. (Xinhua/Fan Peishen)