On the premise that the bed level at Tongguan Station is not affected, the channel volume of reservoir is kept in equilibrium between deposition and erosion, and the deposition in the Lower Yellow River is not increased, the comprehensive usage should be given into full play in united operation of Sanmenxia and Xiaolangdi Reservoir.

Feasibility of lowering Tongguan elevation;

Preliminary study on the effect of Changjiang River-to-Weihe River Water Transfer Project on the scouring and silting in Lower Weihe River and on the falling of Tongguan elevation;

Effects of Wanjiazhai Reservoir operation on Tongguan elevation during spring flood;

To lower and control the elevation of Tongguan station and therefore to alleviate the negative effect induced by reservoir operation on the lower Wei river,a prototype experiment by limiting the pool level not exceeding the maximum value of 318 m in the non-flood season has been conducted since 2003.

Research found that the accumulated sediment deposition and the elevation of Tongguan were affected not only by the current year s flow and pool level conditions,but also by the previous years flow and pool level conditions.

Study on the impact of Tongguan riverbed elevation to the sediment of the downstream Weihe river;

Accordingly, it is urgent and important to study the effect of different Tongguan riverbed elevations on aggradatio.

Analysis on effects from various measures on elevation at Tongguan;

After 2 years operation of the Sanmenxia Reservoir, the elevation at Tongguan run sharply up.

The elevation at Tongguan,a datum point of the Lower Weihe River with a distance of 113km from the Sanmenxia dam,was raised by 5.