基于河道径流可变区间的河流水资源可开发利用率分析

为了确定水电开发活动对河流水资源的可开发利用率,建立分期展布的河道径流可变区间核算方法,其中河道径流包括河道最小生态需水和河道最大洪流,并以西藏拉萨河为例进行核算。结果表明:拉萨河河道最小生态需水和最大洪流年内动态变化分别为29.5~328.3 m3/s和95.1~1 673.4 m3/s。与河道最小生态需水约束相比,河道径流可变区间约束使得拉萨河年调节型水电开发的水资源可开发利用率从60.2%下降到18.7%。指出对于径流丰枯特征十分明显的季节性河流,大型水利工程在平衡径流季节分布的过程中,应该受河道径流可变区间约束,尤其是枯水期最大洪流约束下河道径流量的可增加空间。

Analysis of exploitable rate of river water resource based on variable interval of river runoff

In order to determine the exploitable rate of river water resource by hydropower projects, we established a variable interval calculation method for river runoff of period distribution to calculate the river minimum ecological water demand and the maximum river torrent. Taking Lhasa River in Tibet, China as an example, the minimum ecological water demand and the maximum river torrent were calculated. The results show that the minimum ecological water demand and the maximum river torrent of Lhasa River are 29. 5~328. 3 m³/s and 95. 1~1 673. 4 m³/s, respectively. Compared with the constraints of minimum ecological water demand, the constraints of variable interval of river runoff decrease the water resources exploitable rate by the regulation development of water and electricity in Lhasa River from 60. 2% to 18. 7%. The author of this paper thinks that as for the seasonal rivers which have a significant characteristics of seasonal abundance and dry runoff, large-scale water projects should be constrained by the river variable interval during its balance to the runoff seasonal distribution, especially by the increasable interval of river runoff under the maximum torrent constraint in the dry season.