水电能源科学

沿海平原地区排涝受降雨与潮汐共同作用，水面率作为平原河湖水系自然禀赋的量化，是衡量沿海平原地区水安全保障能力的重要指标。为研究水面率对沿海平原排涝的影响，基于水量平衡原理及极限分析思想，模拟了浙南瓯北街道不同水面率闸自排条件下的排涝过程，并计算分析了平原内河的极限水位、警戒水位极限历时，推导了等效水面率、闸关闭期间内河水位与水面率的关系。结果表明，水面率与平原的调蓄能力正相关，闸关闭时内河水位与水面率成反比关系，水位增长速率与水面率的平方成负反比关系，水面率降低，内河水位增长速度加快、峰值变大、峰现提前、高水位历时延长；内河水位先于警戒水位历时收敛于极限值；排涝闸规模宜为0.9～2.0 m/km²,低水面率时沿海平原区域排涝分析应考虑以潮为主的雨潮组合工况；水面率已超出了传统的水域范畴，建议引入等效水面率拓展水面率的广度，以更好地衡量平原滞涝、排涝能力。

Drainage in coastal plain areas is jointly influenced by rainfall and tidal dynamics. The water surface ratio(WSR), a quantitative indicator of the natural water network endowment in plains, is critical for assessing flood security capacity in coastal regions. To study the impact of WSR on coastal plain drainage, the principle of water balance and limit analysis method were employed for simulating the drainage process under sluice self-drainage conditions with different WSR in the Oubei subdistrict of southern Zhejiang. The limit water level and limit duration of warning stages were analyzed, and the equivalent water surface ratio(eWSR) and relationships between water level and WSR during sluice closure were derived. The results show that the WSR exhibits a positive correlation with the flood storage capacity of the plain; When the sluice gate is closed, the water level of the inland river is inversely proportional to the water surface rate, and the rate of water level growth is negatively inversely proportional to the square of the water surface rate; When WSR decreases, the growth rate of water levels accelerates, peak values increases, peak occurrences advances, and high-water-level duration prolongs. Water level converges to the limiting value faster than the duration of warning stage. The recommended drainage sluice capacity for coastal plain ranges from 0.9 to 2.0 m/km², and the combination of rain and tide which tide is dominant should be considered in the analysis of regional drainage capacity in the low WSR regions. The eWSR is proposed to expand the dimension of traditional WSR, enabling a more comprehensive assessment of the water retention and drainage capacities of plains.