Estimation of ammonia nitrogen load from nonpoint sources in the Xitiao River catchment, China

Ammonia nitrogen (NH4+-N) is one of the three main forms of total nitrogen (TN). Most studies have estimated the load of TN from nonpoint sources instead of one specific form. The relationship between land use and concentrations of NH4+-N in runoff was analyzed using the hydraulic analysis functions of a Geographic Information Systems (GIS), and the annual loads of NH4+-N in the Xitiao River catchment were estimated according to model results. The results suggested that the calculated annual loads of NH4+-N...     

Design of a water quality monitoring network in a large river system using the genetic algorithm

Despite several decades of operations and the increasing importance of water quality monitoring networks, the authorities still rely on experiential insights and subjective judgments in siting water quality monitoring stations. This study proposes an integrated technique which uses a genetic algorithm (GA) and a geographic information system (GIS) for the design of an effective water quality monitoring network in a large river system. In order to develop a design scheme, planning objectives were identified for water quality monitoring networks and corresponding fitness functions were defined using linear combinations of five selection criteria that are critical for developing a monitoring system. The criteria include the representativeness of a river system, compliance with water quality standards, supervision of water use, surveillance of pollution sources and examination of water quality changes. The fitness levels were obtained through a series of calculations of the fitness functions using GIS data. A sensitivity analysis was performed for major parameters such as the numbers of generations, population sizes and probability of crossover and mutation, in order to determine a good fitness level and convergence for optimum solutions. The proposed methodology was applied to the design of water quality monitoring networks in the Nakdong River system, in Korea. The results showed that only 35 out of 110 stations currently in operation coincide with those in the new network design, therefore indicating that the effectiveness of the current monitoring network should be carefully re-examined. From this study, it was concluded that the proposed methodology could be a useful decision support tool for the optimized design of water quality monitoring networks.     

Analyses of airborne Be concentrations in Hong Kong using back-trajectories

A total of 71 air samples were collected in Hong Kong area from November 2001 to February 2003 using a high-volume air sampler and a high-volume cascade impactor with five atmospheric pressure stages. The ⁷Be radioactivity on each stage was measured using a high-efficiency germanium gamma-ray spectrometer. From the radioactivity of stages, the total airborne ⁷Be radioactivity was determined. The activity median aerodynamic diameter (AMAD) of ⁷Be-associated atmospheric aerosols was found to be 0.22–1.11 μm and the geometric standard deviation (GSD) was found to be 1.2–10.5. With the assumed mean growth rate (MGR) of atmospheric aerosols of 0.004–0.005 μm h⁻¹ and the size of Aitken nuclei of 0.015 μm, the residence times of ⁷Be-associated atmospheric aerosols were also found from the AMAD.Three-dimensional 4-day back-trajectories were obtained using the HYSPLIT model from NOAA Air Resources Laboratory. These trajectories were used with the measured ⁷Be radioactivity to construct regional ⁷Be intensity fields for four different altitude levels (less than 1000, 1000–2000, 2000–3000 and above 3000 m) with a Geographic Information System (GIS). Low ⁷Be intensities were found to have advected from low altitudes (less than 1000 m) and oceanic areas. The ⁷Be intensities increased for the higher intensity field layers.By comparing the time taken for air masses to come from the ⁷Be source to Hong Kong and the residence time determined from the AMAD of ⁷Be-associated atmospheric aerosols, good agreement was found if the mean growth rate of 0.005 μm h⁻¹ for atmospheric aerosols was used, and the use of back-trajectories was shown to be satisfactory even up to about 6.5 d. By using the residence time with a MGR of 0.005 μm h⁻¹, the ⁷Be source was found to be relatively well confined in the areas of Mongolia and southeastern Siberia, which further supported that the association of ⁷Be source with the Siberian anticyclone.     

HYDROLOGIC PARAMETERIZATION OF WATERSHEDS FOR RUNOFF PREDICTION USING SWAT1

ABSTRACT: The use of continuous time, distributed parameter hydrologic models like SWAT (Soil and Water Assessment Tool) has opened several opportunities to improve watershed modeling accuracy. However, it has also placed a heavy burden on users with respect to the amount of work involved in parameterizing the watershed in general and in adequately representing the spatial variability of the watershed in particular. Recent developments in Geographical Information Systems (GIS) have alleviated some of the difficulties associated with managing spatial data. However, the user must still choose among various parameterization approaches that are available within the model. This paper describes the important parameterization issues involved when modeling watershed hydrology for runoff prediction using SWAT with emphasis on how to improve model performance without resorting to tedious and arbitrary parameter by parameter calibration. Synthetic and actual watersheds in Indiana and Mississippi were used to illustrate the sensitivity of runoff prediction to spatial variability, watershed decomposition, and spatial and temporal adjustment of curve numbers and return flow contribution. SWAT was also used to predict stream runoff from actual watersheds in Indiana that have extensive subsurface drainage. The results of this study provide useful information for improving SWAT performance in terms of stream runoff prediction in a manner that is particularly useful for modeling ungaged watersheds wherein observed data for calibration is not available.     

旱涝气候监测、预警分析业务系统及服务

旱涝监测、预警分析业务系统系应用ＦＯＲＴＲＡＮ７７,ＢｏｒｌａｎｄＣ和Ｆｏｘｐｒｏ等语言混合编写而成,系统软件结构合理,界面友好,操作灵活方便。该系统建立了基本气候资料、旱涝指标和旱涝灾情等数据库,实现了实时气象资料接收,旱涝信息的统计、检索、列表显示和图形分析显示等功能,能实时、有效地监测、预警旱涝气候灾害的发生、发展,在为有关部门提供抗旱防洪决策科学依据中发挥了重要的作用。     

ARC/INFO软件在矿区土地复垦中的应用

矿区土地复垦是一项极其综合的系统工程，其整个过程涉及最大量的空间数据与空间信息，利用具有强大的空间分析和数据处理功能的地理信息系统（ＧＩＳ）对其进行处理必然会提高土地复垦的效率和科学化水平并促进矿区土地复垦技术的发展。本文结合ＧＩＳ软件ＡＲＣ／ＩＮＦＯ，论述了其在矿区土地复垦中的应用。     

连云港市环境与社会经济协调发展研究

将可持续发展指标作为环境与社会经济协调发展程度的研究指标体系 ,按照协调发展度的大小将环境与社会经济的协调发展状况划分为 3大类 1 0小类 30个基本类型。研究表明 ,连云港市协调发展度逐年提高 ,目前处于勉强协调发展类环境滞后型     

城市污水管网地理信息系统设计

以地理信息系统(GIS)为技术支持。结合污水管网管理的实际需求。在VB环境下利用GeoMap控件进行二次开发，建立了污水管网地理信息系统。该系统充分发挥了GIS对空间、属性数据的编辑、管理、显示和查询的功能，并实现了在GIS环境下对污水管网流量的计算和水质的分析功能。     

GIS技术在自然保护区规划中的应用

通过对GIS技术在自然保护区规划中应用现状的综合分析,探讨了该技术目前的研究热点、发展趋势和存在的问题.目前该领域研究热点是GIS技术如何与遥感(RS)和全球定位系统(GPS)技术有机结合;如何有效处理大量观测调查数据中存在的不确定性是目前面临的主要问题之一;而GIS制图出图技术如何与图形处理软件Photoshop等有...     

Environmental indicators GIS of the Catalan coast

This paper describes the environmental indicators GIS of the Catalan coast, Spain. The spatial data model is based on vector and raster layers with three main modules: the biodiversity, the general biophysical and the socioeconomic. Presently, the database has a number of pressure and impact indicators that have been used to model the components and structure of the system and are suggested to build ecological resilience. Special interest has been given to the analysis of functional groups of species that are relevant to the dynamics of the coastal system, and preliminary results are presented. This system constitutes a user-oriented analytical and monitoring tool for coastal zone managers and researchers. Although, the system is under development it is expected that resulting spatial indicators of environmental condition can be used to promote more sustainable coastal strategies and actions in the Catalan coast.