Nitrate Removal in a Restored Spring‐Fed Wetland,Pennsylvania, USA1

ABSTRACT:  In 2001, the 1.04‐ha Hornbaker wetland in south‐central Pennsylvania was restored by blocking an artificial drainage ditch to increase water storage and hydraulic retention time (HRT). A primary goal was to diminish downstream delivery of nitrate that enters the wetland from a limestone spring, its main source of inflow. Wetland inflow and outflow were monitored weekly for two years to assess nitrate flux, water temperature, pH, and specific conductivity. In Year 2, spring discharge was measured weekly to allow calculation of nitrate loads and hydraulic retention time. Surface runoff was confirmed to be a small fraction of wetland inflows via rainfall‐runoff modeling with TR‐55. The full dataset (n = 102) was screened to remove 13 weeks in which spring discharge constituted < 85% of total inflows because of high precipitation and surface runoff. Over two years (n = 89), mean nitrate‐nitrogen concentrations were 7.89 mg/l in inflow and 3.68 mg/l in outflow, with a mean nitrate removal of 4.19 mg/l. During Year 2 (n = 47), for which nitrate load data were available, the wetland removed an average of 2.32 kg N/day, 65% of the load. Nitrate removal was significantly correlated with HRT, water temperature, and the concentration of nitrate in inflow and was significantly greater during the growing season (5.36 mg/l, 64%) than during the non‐growing season (3.23 mg/l, 43%). This study indicates that hydrologic restoration of formerly drained wetlands can provide substantial water quality benefits and that the hydrologic characteristics of spring‐fed wetlands, in particular, support effective nitrogen removal.     

Improved Bankfull Discharge Prediction Using 2‐Year Recurrence‐Period Discharge1

Abstract:  Knowledge of bankfull discharge (Q_bf) is essential for planners, engineers, geomorphologists, environmentalists, agricultural interests, developments situated on flood prone lands, surface mining and reclamation activities, and others interested in floods and flooding. In conjunction with estimating Q_bf, regionalized bankfull hydraulic geometry relationships, which relate Q_bf and associated channel dimensions (i.e., width, depth, and cross‐section area) to drainage basin area (A_da), are often used. This study seeks to improve upon the common practice of predicting Q_bf using A_da exclusively. Specifically, we hypothesize that predictions of Q_bf can be improved by including estimates of the 2‐year recurrence‐period discharge (Q₂) in regression models for predicting Q_bf. For testing this hypothesis, we used Q_bf estimates from 30 reports containing data for streams that span 34 hydrologic regions in 16 states. Corresponding values of Q₂ and A_da were compiled from flood‐frequency reports and other sources. By comparing statistical measures (i.e., root mean squared error, coefficient of determination, and Akaike’s information criterion), we determined that predicting Q_bf from Q₂ rather than A_da yields consistently better estimates of Q_bf. Other principal findings are (1) data are needed for at least 12 sites in a region for reliable hydraulic geometry model selection and (2) an approximate range of values for Q_bf/Q₂ is 0.10‐3.0.     

抽油机液压刹车制动装置的研究与应用

抽油机刹车系统是作业及维护、保养、检修工作时,确保员工人身安全的重要安全制动装置。目前,刹车系统存在较大安全隐患。文章研究了抽油机刹车安全制动系统的分类及工作原理,分析了存在的安全隐患,提出了采用抽油机液压刹车制动保险销装置。该技术解决了抽油机传统刹车装置存在的问题,并获得了国家专利。应用效果表明:新设计提高了刹车系统安全制动性能。     

Use of tandem circulation wells to measure hydraulic conductivity without groundwater extraction

Conventional methods to measure the hydraulic conductivity of an aquifer on a relatively large scale (10-100 m) require extraction of significant quantities of groundwater. This can be expensive, and otherwise problematic, when investigating a contaminated aquifer. In this study, innovative approaches that make use of tandem circulation wells to measure hydraulic conductivity are proposed. These approaches measure conductivity on a relatively large scale, but do not require extraction of groundwater. Two basic approaches for using circulation wells to measure hydraulic conductivity are presented; one approach is based upon the dipole-flow test method, while the other approach relies on a tracer test to measure the flow of water between two recirculating wells. The approaches are tested in a relatively homogeneous and isotropic artificial aquifer, where the conductivities measured by both approaches are compared to each other and to the previously measured hydraulic conductivity of the aquifer. It was shown that both approaches have the potential to accurately measure horizontal and vertical hydraulic conductivity for a relatively large subsurface volume without the need to pump groundwater to the surface. Future work is recommended to evaluate the ability of these tandem circulation wells to accurately measure hydraulic conductivity when anisotropy and heterogeneity are greater than in the artificial aquifer used for these studies.     

基于散流器的盐雾箱饱和加湿技术研究

目的 提升盐雾箱饱和加湿桶湿式加热性能，保证盐雾试验过程沉降盐雾溶液浓度的稳定，进行盐雾试验箱饱和加湿桶的设计与研究。方法 对饱和加湿桶压缩空气入口和出口进行结构设计，入口采用散流器实现湿式加热，出口设置气水分离器，对出口气流进行气水分离，从而形成较为“洁净”的饱和湿空气。对饱和加湿桶进行性能测试，验证盐雾试验箱饱和加湿方法的有效性。结果 散流器可以使气流在水中形成稳定的流动，有效抑制气流直通液面的浪涌现象，避免液滴飞溅产生，并增大了压缩空气与去离子水的接触面积。供气压力为50~150 kPa时，饱和加湿桶出口气流的相对湿度在不同温度下均可达到83%~90%，且试验过程出口流道无明水喷射。结论 通过对饱和加湿桶的设计，有效提升了湿式加热的效率，并形成较为“洁净”的饱和湿空气，满足盐雾试验要求。     

水利工程建设项目安全生产违规行为分析及监管模式优化

为优化水利工程建设项目安全监管模式、提高安全监管效能,选取山东省2020年重点水利工程质量安全监督报告进行统计分析,梳理出项目法人、代建单位、施工单位、监理单位、设计单位的安全生产违规行为共计1289个,以行为安全“2-4”模型为理论依据,对高频不安全行为产生的原因和规律进行研究。结果显示:水利工程建设项目五方参建单位的高频不安全行为中,安全管理体系程序文件不完善及执行过程不佳的组织不安全行为累计649频次,组织成员安全知识、意识、习惯不佳产生的个人不安全行为累计331频次。据此提出可将监管重点放在对参建单位管理体系的建立与运行上进行组织不安全行为控制,进而控制组织成员个人不安全行为,达到事故预防的目的。     

城市供水管网抗震功能可靠度分析

介绍了供水系统功能分析中的经验渗漏模型,在此基础上给出了一个新的改进算法。将建议模型与供水系统水力分析方法相结合,并引入一般结构分析中的一次二阶矩方法,提出了一类求解供水网络节点及系统功能可靠度的方法。对一典型供水管网进行了流分析,将建议模型计算所得结果与常规渗漏模型进行了比较,结果说明建议模型可行,计算结果合理可信。