Flood Control of the Yellow River

A Journey Down the Yellow River

Flood-control measures include flood-control engineering in the downstream, flood-control reservoir in the trunk and tributary, channel improvement in the upstream and midstream, stabilizing reservoirs in dangerous places, flood-control for key cities and non-engineering measures, etc. The key is the flood-control engineering in the downstream.

1.       Flood-control engineering in the downstream

Flood-control construction in the downstream focuses on stabilizing all the dykes, accelerating the channel improvement, constructing the detention area in the Dongping Lake and shoals, and regulating the estuary.

(1) The stabilization of dykes

Long-time practices show that it is a long-term strategic step for flood control to stabilize dykes in the downstream by “warping, digging, silting and deposition to form a relative underground river”.

Build standardized dykes. According to the requirement of flood control in the downstream, the dykes with less than 12m width on the top, and the 1109.3-kilometer-long dykes whose cross-section can not satisfy the  anti-seepage requirement must be widened. According to the standard of the third grade highway, the dyke tops must be hardened to the width of 6m. In order to cover the danger that occurs on the back land of the river and guarantee that there is no seepage and landslide in the back dyke, based on the requirement of constructing ‘a relative underground river’, we will stabilize 1239.6 km dykes, including strengthening 1180.4km dyke by warping (50km by digging channel), with a width of 100m and the equal height with the designed flood level. Wave prevention forest inside the dykes and ecological forest in the silt-back top must be planted. Cutoff wall of a 59.2km length must be stabilized, 135 dangerous works must be modified and stabilized. 91 guard dams of the dykes along which there is frequent flood must be built, the existing 146 guard dams must be heightened and stabilized. The dykes in the downstream will be a flood-control line, a traffic line in emergency and an ecological landscape line.

(2) Channel improvement

There is a great change of scouring and silting in the wide river section above Gaocun in the downstream. The river regime wanders without regularity. It is very difficult to harness. The application of Xiaolangdi Reservoir has controlled the silting of this river section for a certain period of time. It creates a favorable condition for controlling the Yellow River. This river section must be paid more attention.

Based on the practical experience of channel improvement in the lower channel in recent years and the existing projects, it is planned to build and rebuild 53 controlling and diversion works with a length of 93.1 kilometers in the section above Gaocun; and 45 controlling and diversion works with a length of 41 kilometers in the section below Gaocun. To reduce dangers, it is necessary to increase the quantity of using the sausage-mattress dam and the concrete-post dam besides the traditional willow-box stone structures. And at the same time, we should heighten and strengthen 177 controlling and diversion works which can’t reach the required standard.

(3)  Estuary improvement

The estuary improvement is an important part of the flood-control engineering in the downstream of the Yellow River. Considering the present condition that the height of dykes and the strength of some cross-sections are not adequate to the flood-control requirements, left-dike of 43.7 kilometers long should be heightened and widened; 36.5-kilometer-long top should be hardened. 77.5 kilometer-long anti-wave forest should be planted along the river. Meanwhile, 4 dangerous works and 7 control-diversion works should be continuously built and 9 control-diversion works should be heightened and strengthened.

(4)  Flood control engineering in the downstream of the Qinhe river

Part of the dikes along the downstream of the Qinhe River below Wulongkou are not stable enough and there exist many hidden dangers. It is planned to widen 44.3 kilometer left levee and stabilize 19.5 kilometer dyke by warping; to strengthen 42 kilometers banquette on the back of the right dike. Pressure grouting and crown hardening should be done, and 13 gates be transformed, 17 dangerous works be built or expanded.

(5)  Dongpinghu Flood Detetion District

Although the Xiaolangdi reservoir has been set up, Dongpinghu detention project is still the critical flood control engineering, which is related to the safety of the narrow part of the river in Shandong Province, it is the focal part of future construction. So it is planned to strengthen 77.8 kilometer dikes by using cut-off walls; to transform the secondary lake dike -- Baliwan Gate Station; to dredge the culverts; to height and strengthen the Daqinghe River embankment; and to reinforce and alter the control and diversion works and dangerous works.

To ensure the safety of the residents in the Dongping Lake’s detention district, it is planned to adopt two ways--building village pedestal and temporary withdrawal to avoid the flood on the spot. In the new lake area, we will adopt the temporary withdrawal and build 100km retreating road; in the old lake area, we will build village pedestal to avoid flood on the spot, the pedestal is 391.6 million square meters.

(6) The safety construction in the shoal

To ensure the safety of the shoal along the downstream, it is planned to organize migration of the residents living within 1 km from the bank. The number of the migration is 467 thousand. According to the building standard of the migrants town, an area of 7.946 million square meter on the habilitation is needed, and village pedestal of 76.44 millions square meters are needed for the safety of 1.274 million people to avoid the flood. In the down-draught area in Fengqiu County, we will build 200km retreating road to facilitate the temporary withdrawal of 228 thousand residents.

2. Flood control reservoir in the trunk stream and tributary

(1) Utilize the combining force of the present reservoirs, and make full use of their sediment reduction and flood control. 

In recent terms, while strengthening the forecast of flood, runoff, and sediment, it is necessary to comply a yearly plan about water and sand regulation, conduct the real-time operation carefully, carry out the flood control and sediment reduction in the flood period to optimize the relationship of water and sand, enhance the efficiency of sediment transport in the downstream, and alleviate the sedimentation accumulated in the downstream.

(2) Further improve the system of flood control and sediment reduction engineering system

For the improvement of the system of flood control and sediment reduction, it is planned to finish building the Hekou reservoir by 2010 and to accelerate the preparatory work of Guxian multi-purpose project to start the construction as early as possible.

Guxian multi-purpose project is located in the downstream of Shanxi and Shaanxi Gorge on the north trunk of the Yellow River. It can basically control the flood from Hekouzhen to Longmen and 59 percent of sediment in the Yellow River. The total storage capacity is 15.3 billion cubic meters, the usable storage is 4.65 billion cubic meters. Guxian reservoir can intercept sand and reduce 7.7 billion tons of sedimentation in the downstream channel. When it is combined with the Xiaolangdi reservoir, it can control silting and riverbed rising significantly for a long period of time, meanwhile, it can reduce nearly 5.4 billion tons of sedimentation in the channel from Yumenkou to Tongguan, and lower the elevation of Tonguan, create favorable conditions for the improvement of the channel from Yumen to Tongguan and the downstream of the Weihe River. The application of reservoir to flood control can lower the detention level and sedimentation of Sanmenxia reservoir in big flood, and reduce the rate of flood downdraft into the Wehei River.

Hekoucun Reservoir is located in the downstream mouth of the last gorge of the Qinhe River. The total storage capacity is 3.3 billion cubic meters. After completion, flood peak discharge at Xiaodong Station of the Qinhe River can be reduced from 9500 cubic meters per second to 4000; flood control return period can be raised from 20 years to 200 years, and the threat on the downstream of the Qinhe River can be largely mitigated. At the same time, the flood peak discharge can be further cut down in the downstream of the Yellow River.

3.Channel training in the upper and middle reaches  

(1) Section between Ninxia and Inner Mongolia

The section between Ninxia and Inner Mongolia is plain, and it is 869.5 kilometers long. The height of most dikes is not enough, channel training works are insufficient, the mainstream swings frequently, and the trans-dike buildings can not meet the standards, which is a threat to flood control. Since 1986, the dike has been breached 4 times in ice flood, which greatly affected the economic and social development in the region.

To solve the problem of flood control and ice prevention in this section, it is necessary to heighten 670.6 kilometers long dike, build 17.4 kilometers long dike and 6 anti-danger works, and expand 13 anti-danger works. The trans-dike projects will be merged and transformed, meanwhile, the gullies’ inlets of the Yellow River should be regulated. 18 control and diversion works ought to be established, 31 control and diversion works should be expanded, 1,9000 residents who live in the floodplain below Shizuishan should migrate to outside.

(2) Section from Yumenkou to Tongguan

The length of this section is about 130 kilometers. It’s an alluvial river. Scouring and silting are especially violent there. The shore usually collapses, which often triggers the lift-irrigated stations on both banks to lack water. The building of 15 control and diversion works and bank protection works is in great need, 19 works should be heightened and strengthened.

(3) Section from Tongguan to Sanmenxia dam and the downstream of the Weihe River

This section is about 110 kilometers long. It belongs to Sanmenxia reservoir area. To effectively control the shore-collapse, it is necessary to build and rebuild 8 channel regulation works, 26 anti-erosion and anti-wave works, and heighten and strengthen 3 works.

To resolve the problem of flood control in the downstream of the Weihe River, 98.3 kilometers long main dikes should be heightened, 15.7 kilometers long dykes should be strengthened by warping, 143.1 kilometers long dike should be grouted by cone drilling, and 98.3 kilometers long crown should be hardened. Besides, 11 channel regulation works should be rebuilt, and 15 kilometers long dikes on Nanshan tributary should be stabilized.

In the area below 335 m elevation in the downstream of the Weihe River, 23,000 people return from outside. According to the flood-control principles, protection-dike should be heightened and strengthened according to requirements. 197,000 m2 refuge platform should be constructed to avoid the flood, and 37 kilometers long retreat road should be built.

In order not to let the elevation of Tongguan continuously goes up, it is planned to dredge the section close to Tongguan based on the rational utilization of the Sanmenxia reservoir. If Guxian multipurpose project can be put into practice, Tongguan elevation will be further lowered and controlled in the future.

4. Dangerous reservoir reinforcement and the flood control in major cities

(1) Dangerous reservoir reinforcement

At present, there are still 83 large and medium-sized reservoirs running with problems along the Yellow River (including 12 large ones and 71 medium-size ones). To guarantee the safety of the life and property in the downstream, it is imperative to accomplish the reinforcement of dangerous reservoirs.

(2) Flood control in major cities

At present, there are 8 provincial capital cities and 5 district cities in the Yellow River Basin. They are Xining, Lanzhou, Yinchuan, Huhehaote, Taiyua, Zhengzhou, Ji’nan, Baotou, Kaifen, Shizuishan and Luoyang. The flood control in these cities still can’t meet the standards. For the safety of these cities, it is essential to reinforce the flood control constructions in the above 13 cities and to make it reach the standards soon. We should pay attention to the flood avoidance while constructing cities. It is forbidden to occupy the poundage area and flood channel. The requirement of river flood control should be taken into consideration comprehensively when developing various fundamental facilities. Special emphasis should be laid on storm drainage facilities in downtown area.

5. Non-engineering flood control measures

To increase the accuracy of hydrologic prediction and observation, it is planned to enhance the construction of hydrologic measurement facilities and equipment, and hydrologic prediction service system. Emphasis should be put on upgrading the equipment of the hydrologic stations on the trunk and the control stations at the tributary inlets, such as Tongguan Station, Huayuankou Station and Gaocun Station. A flood warning system covering the section from Xiaolangdi to Huayankou and a weather observation radar detection system covering the section from Hekou to Sanmenxia should be established.

Flood control teleconference system, decision-making and command system and flood control information net need to be set up to enhance the ability of flood control decision-making. In order to reduce the investment for dealing with emergency, shorten the time of handling emergency, and quickly control the danger, 15 “24-hour, prompt, flexible” mobile emergency-handling teams should be established, and the current 20 teams ought to be upgraded.