小型季节性河流生态补水需水量及调度方案研究

针对目前城市河流经常断流的突出问题, 以重庆主城典型重污染河流伏牛溪为例, 开展城市小型季节性河流生态补水自动调度方案的研究。通过分析伏牛溪年内径流特征, 确定了其补水时段为每年的11月~次年4月;通过计算伏牛溪生态环境需水量, 认为对于小型季节性河流的补水不应一味地追求常年丰沛、稳定的水量, 而应以重塑季节性河流天然健康的自然流态为目标, 从而提出了一种基于天然健康需水量的生态补水调度方案, 并制定了河源水库电动阀门及补水泵的运行控制策略等具体技术措施。结果表明, 采用该调度方案, 不仅能实现伏牛溪生态补水系统的自动化运行, 而且与现有补水系统运行方式相比, 可节能67.4%, 为补水系统的可持续运行创造了条件。

RESEARCH OF ECOLOGICAL WATER COMPENSATION DEMAND AND AUTOMATIC SCHEDULING SOLUTIONS FOR SMALL SEASONAL STREAM

Flow break of urban streams has been an urgent issue in many cities, some technical measures should be implemented to restore the ecological environment of such rivers. To solve this problem, a case study of ecological water compensation dispatch scheme on the Funiu River, a heavily polluted river in Chongqing, was investigated in this paper. Firstly, the characteristics of the annual runoff of the Funiu River were analyzed. Monthly runoff data of the Funiu River from 1960 to 2004 was obtained using the hydrologic analogy method, and its annual average runoff was 0.245 m³/s. The concentration degree was 0.48 and concentration period was 191.4° as a result of the inner annual runoff characteristics analysis, demonstrating that duration of the wet season was nearly equal with the dry season. The rainfall was mainly concentrated in July. Meanwhile, ecological water compensation time was determined to be November to next April accordingly. Secondly, research on eco-environmental water requirement was carried out for the Funiu River, the results were shown as follows: basic ecological flows in the wet season is 0.147 m³/s, while in the dry season is 0.098 m³/s; diluting and self-cleaning water demand in the wet season is 1.45 m³/s, while in the dry season it is 0.49 m³/s. Moreover, landscape water demand, evaporation and leakage water demand, and outer river water demand is 2.546 m³/s, 0.02 m³/s and 0.02 m³/s, respectively. Above all, eco-environmental water requirement of the Funiu River is 2.586 m³/s. According to the water resource condition of the Funiu River basin, the calculated result of eco-environmental water demand is difficult to meet. Therefore, we consider that the ideas of ecological water supplement on these small seasonal rivers should be changed, plentiful and stable flow should not be pursued all the year round for the small seasonal river, it would be better to understand the connotation of eco-environmental water demand from a new perspective. Consequently, an automatic ecological water compensation dispatch scheme was brought out, aiming at reshaping the Funiu River with natural seasonal health. Furthermore, the control strategy of the make-up pump and the electric valve in the reservoir at the river source was formulated. The result showed that the technical solutions not only realized the automatically running of ecological water compensation system, but also saved 67.4% energy compared with present operation mode. The result of this research showed that the solutions could well guarantee the ecological water compensation system running continuously.