USING A DISTRIBUTED ROUTING RAINFALL-RUNOFF MODEL1

ABSTRACT: Urban storm water data from four catchments near Miami, Florida, were collected and compiled by the U.S. Geological Survey and were used for testing the applicability of deterministic modeling for characterizing storm water flows from small land use areas. The four sites were:

相似文献   

Wild pig populations in the National Parks

Populations of introduced European wild boar, feral pigs, and combinations of both types (all Susscrola L.) inhabit thirteen areas in the National Park Service system. All parks have relatively stable populations, with the exception of Great Smoky Mountains National Park, which reported a rapidly expanding wild boar population. Suspected and documented impacts were apparently related to pig densities and sensitivity of the ecosystem; the three largest units with dense wild pig populations reported the most damage. Overall, wild pigs are a relatively minor problem for the Park Service; however, problems are severe in at least three parks, and there is potential for invasion of wild boars into several additional parks in the Appalachian Mountains. More specific information is needed on numbers of wild pigs and their impacts in the various parks.     

WATER QUALITY PROJECTIONS: PREIMPOUNDMENT CASE STUDY1

ABSTRACT: Recent regulations require impact statements for major water development projects, including reservoirs that will be used for water supply, recreation, and pollution control. A water quantity/quality model was developed and used for making water quality projections of a proposed reservoir in Montgomery County, Maryland. The study area is uncommon in that there is an extensive water quality data base. The results indicate that land use changes will have a significant effect on water quality and that the proposed reservoir will improve the quality of the surface waters downstream from the reservoir. A major effect of land use changes is the increase in the variability of water quality.     

我国城市化过程中应注意土地资源减少的几个问题

本文着重论述了在我国城市化过程中应注意的城市建设无度占用土地和耕地,以及城市土地利用结构不合理和利用率低下等土地资源减少的问题。     

吉林省区域经济发展的城市化对策研究

在分析吉林省区域经济发展、城市化现状的基础上，总结了吉林省城市化对区域经济发展拉动效应差的主要阻碍性因素，并运用城市与区域相互作用的理论，提出了促进大城市功能扩散、城镇体系重构、城市整合、城乡一体化以及加强城市基础设施和生态环境建设的建议，以增强城市化的区域效应，促进吉林省经济健康有序地发展。     

云南地区地震灾害损失的基本特征

云南是我国地震灾害损失最为严重的地区之一。地震灾害损失评估标准实施以来，云南地区积累了较丰富的地震灾害损失评估资料。以1992～2001年云南地区破坏性地震的灾害损失评估资料为基础，分析了地震灾害损失随时间的变化特征，初步探讨了地震震级与受灾人口、人员伤亡和地震灾害经济损失等方面的关系。结果表明：(1)随着社会经济的不断发展和社会财富的不断积累，等同地震能量所造成的经济损失呈逐渐增大的趋势；(2)在空间上，由于各灾区的经济发展状况不同，等同地震能量所造成的灾害损失存在着地区差异性；(3)地震灾害损失随震级增大而增大，但二者之间并非简单的线性关系，其中生命线工程及其它特殊工程结构、重大工程设施、大型企业等的经济损失随震级的增大而以更大的比例增大。     

In situ Measurement of Daphnia longispina Grazing on Algae and Bacteria in a High Mountain Lake (Lake Paione Superiore,Northern Italy) using Fluorescently Labeled Cells

Grazing impact of Daphnia longispina on phytoplankton and bacteria in Lake Paione Superiore (Northern Italy) was evaluated using fluorescently labeled cells in short-term in situ experiments. Structure and size distribution of Daphnia were studied weekly from its appearance in July to its decline in September. Relative importance of algae and bacteria in the diet varied over time, as did consequently the relative impact of Daphnia on the phytoplankton and bacteria populations. Biomass of bacteria in the diet of Daphnia varied from 1 to 42%, and was highest at the beginning of population development when young individuals dominated. The percent biomass of algae in the diet increased with population development, ranging from 58 to 99%. Daphnia population consumed per hour 0.04–1.8% of bacteria and 0.3–17.6% of phytoplankton abundances.     

HYDRAULIC GEOMETRY RELATIONSHIPS FOR URBAN STREAMS THROUGHOUT THE PIEDMONT OF NORTH CAROLINA1

ABSTRACT: Hydraulic geometry relationships, or regional curves, relate bankfull stream channel dimensions to watershed drainage area. Hydraulic geometry relationships for streams throughout North Carolina vary with hydrology, soils, and extent of development within a watershed. An urban curve that is the focus of this study shows the bankfull features of streams in urban and suburban watersheds throughout the North Carolina Piedmont. Seventeen streams were surveyed in watersheds that had greater than 10 percent impervious cover. The watersheds had been developed long enough for the streams to redevelop bankfull features, and they had no major impoundments. The drainage areas for the streams ranged from 0.4 to 110.3 square kilometers. Cross‐sectional and longitudinal surveys were conducted to determine the channel dimension, pattern, and profile of each stream and power functions were fitted to the data. Comparisons were made with regional curves developed previously for the rural Piedmont, and enlargement ratios were produced. These enlargement ratios indicated a substantial increase in the hydraulic geometry for the urban streams in comparison to the rural streams. A comparison of flood frequency indicates a slight decrease in the bankfull discharge return interval for the gaged urban streams as compared to the gaged rural streams. The study data were collected by North Carolina State University (NCSU), the University of North Carolina at Charlotte (UNC), and Charlotte Storm Water Services. Urban regional curves are useful tools for applying natural channel design in developed watersheds. They do not, however, replace the need for field calibration and verification of bankfull stream channel dimensions.     

SPATIALLY EXPLICIT HYDROLOGIC MODELING OF LAND USE CHANGE1

ABSTRACT: Using a Geographic Information System (GIS), a method is presented to develop a spatially explicit time series of land use in an urbanizing watershed. The method is prefaced on the existence of independent observations of land use at different times and data that describes the spatial‐temporal land use transition characteristics of the watershed between these two points in time. A method is then presented to generalize the TR‐55 graphical method, a common lumped hydrologic model for estimating peak discharge, for use in a spatially explicit scheme. This scheme predicts peak discharge throughout a watershed, rather than at a single selected watershed outlet. Coupling these two methods allows the engineer to model both the temporal and spatial evolution of peak discharge for the watershed. An illustrative watershed in a suburban area of Washington, DC is selected to demonstrate the methods. The model results from these analyses are presented graphically to highlight the complex features in peak discharge behavior that exist both spatially, as a function of position within the watershed drainage network, and temporally, as the watershed undergoes urbanization. These features are not commonly noted in most hydrologic analyses but are captured in these analyses because of the high spatial and temporal resolution of the methods presented. The physical implications of the modeled results are discussed in the context of the information content of a stream gauge located at the overall outlet of the illustrative watershed. This work shows that the common practice of transposition of gauge information to locations internal to the watershed would neglect internal variability in peak discharge behavior, and could potentially lead to the determination of inappropriate design discharges.