BEIJING, July 12 (Xinhua) -- Water levels in the Yangtze River and the Yellow River are rising as intense downpours continue.

Branches of the Yangtze River in its upper reaches, the longest river in China, have braced for severe floods. Local authorities said the second flood peak of the Yangtze River this year is forming in its upper reaches.

Peak flow at the Three Gorges reservoir is expected to reach 58,000 cubic meters per second on Thursday, according to the hydrographic office of the Yangtze River water resources commission.

The office issued an orange alert for floods Wednesday.

China has a four-tier color-coded weather warning system, with red the most severe, followed by orange, yellow and blue.

The flood control and drought relief headquarters of the Yangtze River also organized emergency response teams Wednesday afternoon and worked with reservoirs in the upper reaches of the river to reduce the pressure that floods have brought to southwest Sichuan Province and Chongqing Municipality.

So far, around 52,000 Chongqing residents affected by floods have been relocated to safer places.

Train services on the Xi'an-Chengdu Railway, linking Shaanxi and Sichuan, were suspended on Thursday due to rising water levels in Fujiang River, a tributary of the Yangtze River, according to China Railway Chengdu Group Co., Ltd.

The local meteorological department said storms will hit the area Friday and Saturday.

The flood control and drought relief headquarters of the Yangtze River has dispatched teams to work with affected provinces and cities, providing technical guidance, helping rescue people, and mitigating losses caused by floods.

Water levels in the Yellow River, China's second-longest river, and its branches continue to rise after the first flood peak came days ago.

The flood control and drought relief headquarters of the Yellow River has called for relevant departments in Qinghai, Gansu, Shanxi, Shaanxi, Ningxia Hui Autonomous Region, and Inner Mongolia Autonomous Region to prepare for the flood by evacuating potentially affected people and strengthening the monitoring of reservoirs and dams.