黄河流域产水产沙、输移和沉积系统的划分

根据Schumm提出的河流系统的理论对黄河流域地貌系统进行了划分。结果表明 ,整个黄河流域地貌系统可以很明确地分为产水产沙系统、输移系统和沉积系统 ,其模式与Schumm的理想流域模式非常吻合 ,同时又表现出其特殊性。以河口镇为界 ,黄河流域上游和中下游两部分分别具有对应的产水系统、产沙系统和河道输移系统 ,各子系统处于动态变化过程中 ,存在一种强耦合关系 ,这种特点主要是由黄河流域的历史发育过程决定的。

Decoupling of the Yellow River basin system

The Yellow River is the Mother River of the Chinese nation literally, but it is also a disastrous river with excessive sediment that cannot be easily harnessed. The eco environment is highly vulnerable to the hazardous erosion by water and wind in the middle reaches while channel aggradation, flood menace and frequent change of course occur in the lower reaches. Although great achievements have been made in the Yellow River harnessing and resources utilization, hazards of erosion in the middle reaches and the potential failure of the channel in the lower reaches still exist and the conditions still need to be improved. It is generally accepted that solving the Yellow River problems fundamentally needs systematic considerations. The concept of the fluvial system proposed by Schumm in the 1970s provided a theoretic basis for this issue. The Yellow River system needs to be divided further into subsystems for utilizing the concept of the fluvial system to solve the problems. The Yellow River system is decoupled based on morphological and hydrological data in this paper following Schumm's theory. It meets well with the idealized fluvial system model, thus, an example of the Schumm's idealized fluvial system mode is offered. On the whole, the upper reaches up stream Hekouzhen is the water producing zone (subsystem); the middle reaches between Hekouzhen and Taohuayu section is sediment producing zone; the section from Taohuayu to Lijin is transfer zone;and downstream Lijin is deposition zone. The Yellow River system is a hierarchic structural system. Within the upper reaches of the Yellow River up stream Hekouzhen, upstream Longyangxia is the water producing subzone, the section between Longyangxia and Qingtongxia is the sediment producing subzone, and that between Qingtongxia and Hekouzhen is the transfer subzone. In the middle and lower reaches downstream Hekouzhen, the section from Hekouzhen to Longmen is the sediment producing subzone, that between Longmen and Taohuayu is the water producing subzone, and between Taohuayu and Lijin is the transfer subzone. This decoupling of the Yellow River system is not exclusive, actually, the subsystems are in the dynamic status from the long term point of view. Each subsystem has its characteristics of geomorphologic process. The subsystems from the upstream to the downstream form a cascading system by materials (water and sediment, etc.) movement and energy dissipation. The Yellow River system is also a process response system because the subsystems are closely related with the input and output of the material and energy. These subsystems need to be coupled as a whole. The coupling of the sediment producing zone (the Loess Plateau) and the transfer zone (the channel of the lower reaches) is primarily important to the Yellow River harnessing.