岷江卵石推移质泥沙与数量特性

A STUDY ON THE CHARACTERISTICS AND QUANTITY OF THE PEBBLE. BED LOAD AT THE MINJIANG RIVER

根据区域地质与地貌及其对卵石岩类组成的影响，将岷江下游卵石来源分为三个补给区及汇合区，用各补给区与汇合区的卵石岩类鉴定资料建立计算模式，计算出来自大渡河补给区的卵石占４０．６％，来自岷江上中游补给区占３６．１％，来自青衣江补给区占２３．３％。大渡河补给区卵石汇入百分数为已知，其龚咀水库的卵石数量为６．７７×１０５ｔ／ａ，据此计算出岷江干流卵石数量为１．６６８×１０６ｔ／ａ。该计算数同用卵石磨损方法求出的数值相近。验证表明，计算值与验证值两者只相差１．９％。

This paper summarizes the results of investigations on the pebble bed load (the PBL) with large sorting coefficient at the Minjiang River. In the Minjiang River, the PBL causes serious problems.Due to the difficulties in measurement. there is still a lack of data on the PBL for the main stem of the Min jiang River. The composition of the PBL of the Minjiang River spreads widely. The maximum diameter can be 539mm. More than 91. 1% of the PBI have the hardness more than 6 (measured by Mo-hardness metre). About 84. 5% of specific gravities of the PBL are between 2. 75 to 3. 02.In the light of regional geological and geomorphological conditions and their effect on petrographic composition of the PBL, three source areas of the PBL in the Minjiang River watershed can be identified: the Dadu River, the upper and middle reaches of MinJiang River and the Qingyi River. The coverging region is at the Leshan reach of main stem of the Minjiang River. Based on the evaluation of petrographic composition in the supplying regions and the converging region a computational model is established. The results are that 40. 6% of the PBL come from the Duta River.36. 1% from the upper and middle reaches of MinJiang River and 23. 3% from the Qingyi River. Knowing converging percentage of the Dadu River supplying region and knowing that total amout of the PBL supply from the Gongzhui Reservior of Dadu River is 0. 677 million tons per year.then the amount of the PBL at the main stem of Minjiang River is computed as 1. 668 million tons per year. This numerical value has been checked against the value obtained by wearing method of the PBL at the upper and middle reaches of Minjiang River. which shows that there is only a difference of 1. 9 % between the calculated value checked value.