【作者】 刘莉；

【导师】 程香菊； 周新民；

【作者基本信息】 华南理工大学 ， 土木水利（专业学位）， 2023， 硕士

【副题名】以茜坑水库为例

【摘要】 茜坑水库是深圳市龙华区的引调型水库,作为区内饮用水水源地,库区水质的好坏影响着居民的用水安全。水库封闭且库湾众多、水库长期抽调营养盐浓度超标的东江水入库等特点影响了水库的水环境质量,使得蓝藻水华爆发风险加剧,影响水库水生态健康。为摸清茜坑水库水环境现状与特性,在查阅大量文献资料的基础上,本研究获取了水库的水文、水质、水生生物等数据,分析了水库的历史水体理化性质以及水生生物群落特征。基于AQUATOX模型特点,探究了EFDC与AQUATOX水动力-水质-水生态模型相耦合的方法。校验成功后,针对茜坑水库,使用2019全年的气象、流量、水质和水生生物等数据模拟全库的水位、流速、水龄、营养盐浓度、浮游植物生物量、浮游动物生物量以及鱼类生物量。结合模型模拟结果,对茜坑水库进行水生态状况的分析,同时基于耦合模型对未来气候改变下水库水生态状况进行了一定的预测与分析。模拟结果方便水库管理部门对水库进行针对性的管理,模型也能够预测水库在气候变化下的生态状况。本文主要研究成果如下:(1)成功构建EFDC-AQUATOX三维耦合模型,且三种耦合方案下模型模拟结果基本相同,模型所得水质理化指标的模拟结果与实测值拟合结果较好,五项水质指标的误差均在40%内,证明构建并率定成功的耦合模型能够比较准确地反映茜坑水库水环境整体变化的实际情况。(2)基于EFDC模型模拟的成果,流速与水龄空间差异性显著,与引调型水库形态以及水库引调水模式相关,流速与水龄成反比,流速越大,水体交换越频繁,水龄越小;水质指标在1～5月以及11～12月时垂向差异显著。表层氨氮浓度小于底层,表层硝酸盐氮以及总氮的浓度大于底层,表层的总磷浓度小于底层,叶绿素a浓度是表层浓度大于底层浓度,藻类生长受营养盐的影响,水质指标变化趋势在时间与空间上均符合实际。(3)基于EFDC-AQUATOX耦合模型模拟的成果,除正颤蚓以外,水生生物的生物量在夏季时空间异质性明显。硅藻生物量总体呈现随时间逐渐增大的趋势,蓝藻与绿藻生物量总体呈现先减小后增大再减小的趋势,年末几乎为零。轮虫、枝角类的生物量总体呈现先减小后增大的趋势,摇蚊在1～2月时生物量有短暂的升高,之后生物量一直呈现出减小的趋势,正颤蚓的生物量从年初开始一直呈现出减小的趋势,两种鲤鱼的生物量从年初开始增长,到9月后基本维持不变。(4)绿藻对太阳辐射强度以及风速变化最敏感,硅藻最不敏感,蓝藻的变化更具有规律性,蓝藻以及枝角类生物量受风速影响大,当茜坑水库区域的风速处于2.6m/s～5.8 m/s时,风速与蓝藻、枝角类生物量成正比。水温在0.1℃～0.5℃的变化幅度时,不会影响水库生态系统的演变规律。硅藻生物量与水温成反比,蓝藻、绿藻生物量与水温成正比,蓝藻对水温变化更敏感;轮虫、枝角类生物量与水温成正比,轮虫对水温变化更敏感;正颤蚓生物量变化微小,生物量与水温成正比,相较于浮游动物,底栖动物对水温变化更不敏感;鱼类对水温变化不敏感,鱼类生长主要是受其余水生生物的生物量变化的影响。(5)根据模型计算结果,2020年、2021年、2022年茜坑水库的水生生物的生长规律不会发生改变,与2019年相比,2020年硅藻、正颤蚓、鲤鱼的生物量会增加,枝角类、摇蚊的生物量会减小;2021年正颤蚓、鲤鱼的生物量会增加,蓝藻、绿藻、轮虫、枝角类、摇蚊的生物量会减小;2022年硅藻、绿藻、轮虫、正颤蚓、鲤鱼的生物量会增加,蓝藻、枝角类、摇蚊的生物量会减小。硅藻生物量会随水温升高而降低,蓝藻、绿藻、轮虫、正颤蚓生物量会随水温升高而增加。更多还原

【Abstract】 Xikeng Reservoir is a diversion reservoir in Longhua District of Shenzhen.As a drinking water source in the area,the water quality of the reservoir area affects the water safety of residents.The characteristics of closed reservoir,numerous reservoir bays and long-term pumping of Dongjiang water with excessive nutrient concentration affect the water environment quality of the reservoir,which aggravates the risk of cyanobacteria bloom and affects the water ecological health of the reservoir.In order to find out the current situation and characteristics of the water environment of Xikeng Reservoir,on the basis of consulting a large number of documents,this study obtained the data of hydrology,water quality and aquatic organisms of the reservoir,and analyzed the physical and chemical properties of the historical water body of the reservoir and the characteristics of aquatic organisms.Based on the characteristics of AQUATOX model,the coupling method of EFDC and AQUATOX hydrodynamic-water quality-water ecological model was explored.After successful verification,the data of meteorology,flow,water quality and aquatic organisms in 2019 were used to simulate the water level,flow velocity,water age,nutrient concentration,phytoplankton biomass,zooplankton biomass and fish biomass of the whole reservoir.Combined with the model simulation results,the water ecological status of Xikeng Reservoir was analyzed.At the same time,based on the coupling model,the water ecological status of the reservoir under the future climate change was predicted and analyzed.The simulation results are convenient for the reservoir management department to carry out targeted management of the reservoir,and the model can also predict the ecological status of the reservoir under climate change.The main research results of this paper are as follows :(1)The EFDC-AQUATOX three-dimensional coupling model was successfully constructed,and the simulation results of the three coupling schemes were basically the same.The simulation results of the physical and chemical indexes of water quality obtained by the model were in good agreement with the measured values,and the errors of the five water quality indexes were within 40%.It is proved that the successful coupling model can accurately reflect the actual situation of the overall change of water environment in Xikeng Reservoir.(2)Based on the results of EFDC model simulation,the spatial difference between flow velocity and water age is significant,which is related to the shape of diversion reservoir and the water diversion mode of reservoir.The flow velocity is inversely proportional to the water age.The larger the flow velocity,the more frequent the water exchange and the smaller the water age.The vertical difference of water quality indexes was significant from January to May and from November to December.The concentration of ammonia nitrogen in the surface layer is lower than that in the bottom layer,the concentration of nitrate nitrogen and total nitrogen in the surface layer is higher than that in the bottom layer,the concentration of total phosphorus in the surface layer is lower than that in the bottom layer,the concentration of chlorophyll a in the surface layer is higher than that in the bottom layer,the growth of algae is affected by nutrients,and the change trend of water quality indicators is in line with the actual situation in time and space.(3)Based on the results of EFDC-AQUATOX coupling model simulation,except for tubifex,the biomass of aquatic organisms had obvious spatial heterogeneity in summer.The biomass of diatoms generally showed a trend of increasing with time.The biomass of cyanobacteria and green algae generally showed a trend of decreasing first,then increasing and then decreasing,and it was almost zero at the end of the year.The biomass of rotifers and cladocera showed a trend of decreasing first and then increasing.The biomass of chironomus increased briefly from January to February,and then the biomass showed a decreasing trend.The biomass of tubifex showed a decreasing trend from the beginning of the year.The biomass of the two carps increased from the beginning of the year and remained basically unchanged after September.(4)Green algae are most sensitive to solar radiation intensity and wind speed changes,diatoms are least sensitive,and the changes of cyanobacteria are more regular.The biomass of cyanobacteria and cladocerans is greatly affected by wind speed.When the wind speed in the Xikeng reservoir area is 2.6 m/s ～ 5.8 m/s,the wind speed is proportional to the biomass of cyanobacteria and cladocerans.When the water temperature changes from 0.1 °C to 0.5 °C,it will not affect the evolution of the reservoir ecosystem.The biomass of diatoms is inversely proportional to water temperature,and the biomass of cyanobacteria and green algae is proportional to water temperature.Cyanobacteria are more sensitive to water temperature changes.The biomass of rotifers and cladocerans was proportional to water temperature,and rotifers were more sensitive to water temperature changes.The biomass of tubifex changed little,and the biomass was proportional to the water temperature.Compared with zooplankton,benthic animals were less sensitive to water temperature changes.Fish is not sensitive to water temperature changes,and fish growth is mainly affected by the biomass changes of other aquatic organisms.(5)According to the model calculation results,the growth law of aquatic organisms in Xikeng Reservoir will not change in 2020,2021 and 2022.Compared with 2019,the biomass of diatoms,tubifex and carps will increase in 2020,and the biomass of cladocerans and chironomid will decrease.In 2021,the biomass of tubifex and carp will increase,while the biomass of cyanobacteria,green algae,rotifers,cladocerans and chironomid will decrease.In2022,the biomass of diatoms,green algae,rotifers,tubifex,and carps will increase,and the biomass of cyanobacteria,cladocerans,and chironomid will decrease.The biomass of diatoms decreased with the increase of water temperature,while the biomass of cyanobacteria,green algae,rotifers and tubifex increased with the increase of water temperature.更多还原