Simulation of internal nitrogen release from bottom sediments in an urban lake using a nitrog

Nutrient release from sediment is considered a significant source for overlying water. Given that nutrient release mechanisms in sediment are complex and difficult to simulate, traditional approaches commonly use assigned parameter values to simulate these processes. In this study, a nitrogen flux model was developed and coupled with the water quality model of an urban lake. After parameter sensitivity analyses and model calibration and validation, this model was used to simulate nitrogen exchange at the sedimentewater interface in eight scenarios. The results showed that sediment acted as a buffer in the sedimentewater system. It could store or release nitrogen at any time, regulate the distribution of nitrogen between sediment and the water column, and provide algae with nitrogen. The most effective way to reduce nitrogen levels in urban lakes within a short time is to reduce external nitrogen loadings. However, sediment release might continue to contribute to the water column until a new balance is achieved. Therefore, effective measures for reducing sediment nitrogen should be developed as supplementary measures. Furthermore, model parameter sensitivity should be individually examined for different research subjects.     

湖泊管理组织制度演进及其驱动因素的比较研究——以固城湖和长荡湖为例

以固城湖和长荡湖为对象,运用参与式评估方法和问卷调查获得资料,分析固城湖和长荡湖管理组织制度演进,并在此基础上,运用制度经济学、产权经济学理论和对比分析的方法分析了固城湖和长荡湖管理组织制度演进的驱动因素,分析表明:具有不同利用目标的集团压力之间的力量对比变化是湖泊管理组织制度演进的根本动力;政府部门在湖泊管理中的利益取向与主导管理目标(价值)的一致程度决定其是否能取得湖泊管理主导权的关键因素。最后,文章结合研究结论,给出一些加强湖泊保护的建议。     

南四湖湖区最小生态需水研究

针对南四湖的资料,构建了基于最低生态水位和最小湖区生态耗水的南四湖湖区最小生态需水计算模型。使用天然水位资料统计法、湖泊形态分析法和生物空间最小需求法计算了南四湖最低生态水位。3种计算结果相近。建议的上级湖最低生态水位为33.00m、下级湖为31.38m。基于频率95％的降水等资料,计算的湖区最小生态耗水为6.44亿m3／a。     

湖区地层垂向渗透系数概率分布特征分析

为了确定某湖区湖水与地下水的交换水量,根据湖底地层渗透系数的野外现场测定值,用适线法和蒙特卡罗法对研究区地层垂向渗透系数的概率分布进行拟合,在此基础上,分析了渗透系数试验测定值的可靠性.结果表明:与正态分布和均匀分布相比较,湖底地层垂向渗透系数概率分布较接近对数正态分布;渗透系数超过测定均值的概率在30%以上.     

长江中下游洪水位与河床冲淤关系初探

针对长江中下游近50年来部分水文断面如螺山、城陵矶洪水位抬升明显、高洪水位持续时间加长的问题,统计了大量水位、流量、水流含沙量以及河床地形等实测资料,并进行分析计算.结果表明,长江中下游洪水位变化与河段河床演变及河道形态变化密切相关,江湖淤积及河道形态变化是造成洪水位抬高及高洪水位持续时间加长的主要原因.     

谈河湖疏浚工程实施过程中存在的几个问题

结合近年来江西省河湖疏浚工程的实施,针对各个阶段中出现的涉及设计要求、质量标准、工程计量和施工围堰等方面的问题进行分析,提出相应的解决方法．     

Digitization,digitalization, and digital transformation in accounting,electronic commerce,and supply chains

This paper provides some basic definitions associated with digital transformation in organizations and applies those definitions to accounting, electronic commerce, and supply chains. I also drill down on the dimensions associated with digital transformation, including digital everywhere, integration (across applications and with customers and partners), and the need to reengineer processes. I examine several examples of processes ranging from digitization to digital transformation. I also examine the role of people in digitally transformed organizations and some technologies that are important to continued evolution of digitally transformed organizations. Further, we explore a number of scenarios of digital transformation. Finally, these investigations result in the determination of a number of emerging research issues.     

Water storage strategy in post-flood period for hongze lake based on flood utilizationEI北大核心CSCD

基于洪泽湖的地理地形特征,采用MIKE平台构建了湖泊及其蓄滞洪区联合运用的水文水动力模型,实现了对湖、陆水流运动和水量交换与控制的精细化模拟,并制定了后汛期不同蓄水时机和蓄水方案构成的蓄水策略样本库;通过丰、平、枯多种来水情景大规模的数值模拟,对不同典型年蓄水策略进行了评价和优选。结果表明:若洪泽湖后汛期来水属于丰水年系列,应于9月10—20日偏后期伺机蓄水,采用“先泄后蓄”、泄水效率较高的蓄水策略,尽量避开完整的洪水过程;若来水属于平水年系列,应于9月10—20日偏前期伺机蓄水,采用“先泄后蓄”、泄水效率较低的蓄水策略,在洪水的退水阶段起蓄;若来水属于枯水年系列,应于8月31日—9月10日起蓄,采用“先蓄后泄”的蓄水策略,泄水效率的选择应结合来水预报信息,在洪水的起涨段或中段即可拦蓄。     

气候变化下湖库蓝藻水华发展趋势及防控对策

气候变化影响下，湖库蓝藻水华呈现全球性扩张。本文利用CiteSpace系统梳理了2006—2021年期间相关研究的历史沿革和发展趋势，总结了气候变化下湖库蓝藻水华的变化趋势，分析了气候因子对湖库蓝藻水华的影响及其机制，提出了新形势下蓝藻水华的防控对策。随着气候变化日益加剧，湖库蓝藻水华研究主题已成为了国际前沿热点之一，年发文量递增。气温升高、二氧化碳浓度增加与日照延长直接促进了蓝藻水华，而极端降雨频率升高通过增加营养盐入湖库负荷，风速下降通过促进藻类在湖库表层水体聚集，间接促进了蓝藻水华。适度严格营养盐控制标准，加强山水林田湖草综合治理，提升蓝藻水华预测预警与应急处置能力，对未来气候变化下湖库蓝藻水华防控具有重要意义。     

太湖湖盆取土的环境影响和管理

根据太湖湖盆取土区的自然地理和水环境,论述了湖盆取土对湖体生态将造成较大冲击,强调湖盆取土论证和环境影响评价,取土后的生态修复和补偿措施是取土湖区生态环境保护的关键。最后给出生态维护技术原则和建议。