A MODEL TO ENHANCE WETLAND DESIGN AND OPTIMIZE NONPOINT SOURCE POLLUTION CONTROL1

ABSTRACT: A dynamic, compartmental, simulation model (WETLAND) was developed for the design and evaluation of constructed wetlands to optimize nonpoint source (NPS) pollution control. The model simulates the hydrologic, nitrogen, carbon, dissolved oxygen (DO), bacteria, vegetative, phosphorous, and sediment cycles of a wetland system. Written in Fortran 77, the WETLAND models both free‐water surface (FWS) and subsurface flow (SSF) wetlands, and is designed in a modular manner that gives the user the flexibility to decide which cycles and processes to model. WETLAND differs from many existing wetland models in that the interactions between the different nutrient cycles are modeled, minimizing the number of assumptions concerning wetland processes. It also directly links microbial growth and death to the consumption and transformations of nutrients in the wetland system. The WETLAND model is intended to be utilized with an existing NPS hydro‐logic simulation model, such as ANSWERS or BASINS, but also may be used in situations where measured input data to the wetland are available. The model was calibrated and validated using limited data from a FWS wetland located at Benton, Kentucky. The WETLAND predictions were not statistically different from measured values for of five‐day biochemical oxygen demand (BOD₅), suspended sediment, nitrogen, and phosphorous. Effluent DO predictions were not always consistent with measured concentrations. A sensitivity analysis indicated the most significant input parameters to the model were those that directly affected bacterial growth and DO uptake and movement. The model was used to design a hypothetical constructed wetland in a subwatershed of the Nomini Creek watershed, located in Virginia. Two‐year simulations were completed for five separate wetland designs. Predicted percent reductions in BOD₅ (4 to 45 percent), total suspended solids (85 to 100 percent), total nitrogen (42 to 56 percent), and total phosphorous (38 to 57 percent) were similar to levels reported by previous research.     

湿地综述与新疆湿地研究

湿地(Wetland)是世界上面积最大、分布地域最广泛、生产力最高的景观类型之一,其结构和功能十分独特,对全人类的发展发挥着独特的作用。我国是一个干旱缺水严重的国家,我国西部干旱区水资源与湿地问题突出,对湿地的研究应和"干旱区研究"并行。文中总结了国际与国内对湿地研究与发展状况和趋势,分析了新疆湿地的特征和类型,并提出了新疆湿地存在的问题和一些建议。     

WETLAND BOUNDARY DETERMINATION IN THE GREAT DISMAL SWAMP USING WEIGHTED AVERAGES1

ABSTRACT: A weighted average method was used to analyze transition zone vegetation in the Great Dismal Swamp to determine if a more uniform determination of wetland boundaries can be made nationwide. The method was applied to vegetation data collected on four transects and three vertical layers across the wetland-to-upland transition zone of the swamp. Ecological index values based on water tolerance were either taken from the literature or derived from local species tolerances. Wetland index values were calculated for 25-m increments using species cover and rankings based on the ecological indices. Wetland index values were used to designate increments as either wetland, transitional, or upland, and to examine the usefulness of a provisional wetland-upland break-point. Most increments were designated wetland or transitional when all species were used. Removal of three or five ubiquitous species either gave a wider range of wetland index values with a more variable designation of increments or caused designation of increments to be similar for all layers. The use of locally-derived rankings showed the sensitivity of the weighted averages method to ecological indices of species with large importance values. The weighted average method did not provide for an objective placement of an absolute wetland boundary, but did serve to focus attention on the transitional boundary zone where supplementary information is necessary to select a wetland-upland breakpoint.     

WETLAND BOUNDARIES IN THE NEW JERSEY PINELANDS: ECOLOGICAL RELATIONSHIPS AND DELINEATION1

Wetland protection regulations and guidelines often require the delineation of precise wetland boundaries on a case-by-case basis. In this study, conducted in the New Jersey Pinelands, an ecological characterization of vegetation composition, soil and hydrologic relationships along upland to wetland Pinus rigida - dominated transittions provided the basis for a multiparameter approach to wetland boundary delineation. The transitional data set was analyzed by direct gradient analysis, cluster analysis and ordination. It is concluded that vegetation composition can be a principal factor in delineating wetland boundaries along natural upland to wetland transitions. However, where distinct vegetation changes are not observed, a feature of our study sites, a multiparameter approach should be used.     

寒区湿地软土固结变形特性试验研究

软土的成因不同,其工程性质存在着一定的差异,路基的固结沉降也不一样。为了研究寒区湿地软土固结变形特性,弄清其固结和次固结系数变化规律,对两类软土进行了单向固结压缩试验。试验结果表明,软土在不同的固结压力作用下,其孔隙比-时间对数曲线展布特征有较大的不同,说明固结压力对寒区湿地软土的主、次固结的划分有影响;寒区湿地软土主固结系数随固结压力的增大而减小,次固结系数随固结压力的增大而增大,最后两者都趋于稳定。     

中国湿地生态质量预警研究

简要介绍了中国湿地的特点、主要类型、开发利用现状以及中国湿地生态环境面临的主要问题;分析了湿地生态系统的整体性、结构的复杂性、调控的滞后性、系统的脆弱性与敏感性等4个基本特征,指出了开展湿地生态质量预警研究的理论与实践意义,阐述了湿地生态质量预警系统所包含的警义、警情、警源、警兆、警度和预测模型等基本内容,并提出了构建中国湿地生态质量预警系统的基本思路和方法。     

黄河三角洲湿地生态环境现状的调查研究

通过对黄河三角洲湿地类型及分布的调查以及对三角洲环境空气质量、地表水环境质量、湖泊水库水环境质量、浅海湿地水环境质量和湿地生态系统现状进行了调研,结果表明,三角洲湿地环境均受到不同程度的污染,浅海湿地潜在富营养化的危险,湿地生态系统现状堪忧.     

盐城湿地保护与生态旅游开发

盐城海滨湿地资源丰富，已成为重要的环境资源和旅游资源。从湿地的变化和现状着手，阐述了保护盐城湿地的必要性和重要性，在保护中倡导自养型经济战略——生态旅游。分析了盐城湿地生态旅游开发的可行性，从而提出规划意见，以实现盐城湿地旅游的可持续发展。     

再生水景观河道生态修复水体净化效果研究

天津某再生水景观河道生态修复工程采用了生态修复处理技术以净化和保持河道水质。本文通过对该生态示范工程运行期间的水质净化效果的研究，为盐碱地区同类型景观河道的建设和水体富营养化的防治提供了工程经验和理论依据。     

黄河三角洲滨海湿地的区域自然灾害风险

黄河三角洲是中国典型的滨海河口湿地，具有重要的生态和经济意义。该区域自然灾害频繁，海岸侵蚀、海面上升、风暴潮和黄河断流等主要灾害风险因子之间密切相关。在它们的共同作用下，黄河三角洲滨海湿地面积不断减少，地表结构遭到破坏，生态特征发生改变，生态环境持续恶化，导致滨海湿地不断损失和退化。应从系统的角度认识黄河三角洲滨海湿地与区域自然灾害的关系，科学对待并切实缓解滨海湿地的损失和退化。