新桥河挡潮闸建立前后流域水环境变化机制研究

Study on The Mechanism of Water Enviroment Change Before and After The Establishment of Xinqiao River Tidal Gate

胡文华

11749208

硕士

环境工程

易树平

2019-05-29

2019-06-28

哈尔滨工业大学

深圳

水环境污染作为城市面临的突出环境问题，不仅受到城市居民广泛关注，也是城市可持续发展和宜居程度评价的关键因素。目前城市河流水污染严重，河流生态系统受到严重破坏，水环境恶化程度日益突出，已成为制约“建设美丽城市”的重要因素。在沿海地区，河口挡潮闸大量用于防洪、提高水资源利用率及提升城市水景观等，但挡潮闸建设对于上游河流水环境的影响机制尚不明晰，因此有必要开展挡潮闸建立后流域水环境变化机制研究。本文选取新桥河流域作为研究对象，采用水动力、水化学和数值模拟方法对比挡潮闸建立前后流域内水环境变化情况，分析挡潮闸建立前后流域河水、地下水和底泥变化机制。水位监测结果显示，挡潮闸运行后，丰水期的强降雨及部分时间内挡潮闸景观蓄水水位过高，下游过水断面较小，导致河水水位高于地下水水位，河水补给地下水；中游河水及地下水水位随挡潮闸调度发生变化，但整体变化较小；上游受挡潮闸影响较小，河水与地下水水位变化不大；整体而言，流域内补排关系变化不大，流域内主要补排关系仍为地下水补给河水。水环境监测结果显示，挡潮闸挡住下游污染潮水，流域内河水环境显著提升，与之水力联系密切的地下水环境也因此有所改善；由于挡潮闸前形成水库会造成污染物在闸前聚集，且改变河流流速，导致挡潮闸前的河水中重金属污染加重，底泥中重金属污染减轻，其余河段则呈现出河水中重金属污染减轻，底泥中重金属污染加重的变化规律；校正后的SWAT-LUD模型结果显示，挡潮闸建立后河水-地下水交互量变化较小，挡潮闸前河水补给地下水量略有增大；流域污染负荷结果显示，目前新桥河流域主要污染物为COD、BOD和NH3-N，2018年建闸后河水中COD、BOD、NH3-N、TP的污染负荷比建闸前分别减少了10680kg/a、3516kg/a、2080kg/a、138.9kg/a，大部分子流域内污染负荷有所减少，挡潮闸前的子流域减少量最多，河水水质改善效果较好。本文结合新桥河挡潮闸建设前、后调查、监测、检测与模拟分析，揭示了挡潮闸建设对感潮河流上游河水、地下水及河道底泥等河流水环境的影响机制，并量化研究了挡潮闸对上游河流水环境污染负荷的削减规律。本研究对沿海地区感潮河流水环境质量提升提供了重要理论和技术支撑。

Water environmental pollution, which is a prominent environmental issue faced by the city, not only has aroused great attention from the urban residents but also has become a key factor for the evaluation of urban sustainable development and livability. At present, the serious pollution of urban rivers, damagement of river ecosystems, and the deterioration of water environment have become important restricted factors for the construction of beautiful cities. In the coastal areas, estuarine tidal gate is used for flood control, improving the efficiency of water resource utilization, and upgrading the quality of urban water landscapes. However, the effects of the tidal gate on the upstream region of the basin and the groundwater environment are rarely investigated. In this study, the Xinqiao River Basin was selected as the research object, and a combination of the hydrodynamic, water chemistry and numerical simulation methods was used to investigate the changes of water environment in this basin before and after the tidal gate consrtuction. The mechanisms of river water, groundwater and sediment changes before and after the establishment of the tidal gate were explored. After the tidal gate operation, the increase of rainfall during the wet season and the high water level in the tidal gate resulted in the downstream water cross section was small, which further caused the river water level being higher than the groundwater level, and thus the river water recharged the groundwater. The water level of the middle reaches in the river water and groundwater changed with the tidal gate dispatching, but the overall changes were not significant. The river upstream was less affected by the tidal gate, and the river water and groundwater level showed no great change. In general, the relationship between the replenishment and discharge within the basin was not changed and the groundwater recharged river water was dominant. The results of the water environment suggested that the river water environment within the river was significantly improved because the tidal gate could play a role in intercepting the polluted downstream after its operation. Besides, the quality of groundwater environment which has a close hydraulic relationship with the river water environment was also improved. The results also showed that the concentrations of the heavy metal ions in the upstream of the water river were increased while the concentrations in the sediment were decreased; and the opposite results were found in the remained part of the basin. The reasons for these observed results were the accumulation of the pollutants in front of the tidal gate and hence altered the velocity of the water-flow. The results of the modified SWAT-LUD model indicated that insignificant interaction changes of the river-groundwater before and after the tidal gate establishment, and the river-groundwater recharge amount slightly increased before the tidal gate. After the construction of tidal gate in 2018, the COD, BOD, NH3-N and TP pollution loads in the river water were reduced by 18878kg/a, 6054kg/a, 3592kg/a and 247kg/a, respectively. Further, the pollution loads have been reduced in the sub-basins as well as in the regions before the tidal gates were established, the water quality was improved. Based on the investigation, monitoring, detection and simulation analysis of the construction of the tidal gate of Xinqiao River, this study revealed the influence mechanism of the construction of the tidal gate on the river water environment, groundwater and sediment environment, and quantified the impact of tidal gate on the law of the reduction of pollution loads in the upstream of the river. This study provides important theory and the technical support for the improvement of water environment quality of tidal rivers in coastal areas.

水环境 变化机制 挡潮闸 SWAT-LUD 新桥河

Water environmental Change mechanism Tidal gate SWAT-LUD Xinqiao River

中文

联合培养

南方科技大学

胡文华. 新桥河挡潮闸建立前后流域水环境变化机制研究[D]. 深圳. 哈尔滨工业大学,2019.