Forecasting and visualization of wildfires in a 3D geographical information system

This paper describes a wildfire forecasting application based on a 3D virtual environment and a fire simulation engine. A novel open-source framework is presented for the development of 3D graphics applications over large geographic areas, offering high performance 3D visualization and powerful interaction tools for the Geographic Information Systems (GIS) community. The application includes a remote module that allows simultaneous connections of several users for monitoring a real wildfire event. The system is able to make a realistic composition of what is really happening in the area of the wildfire with dynamic 3D objects and location of human and material resources in real time, providing a new perspective to analyze the wildfire information. The user is enabled to simulate and visualize the propagation of a fire on the terrain integrating at the same time spatial information on topography and vegetation types with weather and wind data. The application communicates with a remote web service that is in charge of the simulation task. The user may specify several parameters through a friendly interface before the application sends the information to the remote server responsible of carrying out the wildfire forecasting using the FARSITE simulation model. During the process, the server connects to different external resources to obtain up-to-date meteorological data. The client application implements a realistic 3D visualization of the fire evolution on the landscape. A Level Of Detail (LOD) strategy contributes to improve the performance of the visualization system.     

A new framework for modeling decentralized low impact developments using Soil and Water Assessment Tool

Assessing the performance of LID practices at a catchment scale is important in managing urban watersheds. Few modeling tools exist that are capable of explicitly representing the hydrological mechanisms of LIDs while considering the diverse land uses of urban watersheds. In this paper, we propose computational modules that simulate the hydrological processes of LIDs including green roof, rain garden, cistern, and porous pavement. The applicability of the modules was evaluated using plot scale experimental monitoring data. The effectiveness of LIDs was investigated in a highly urbanized watershed located in Austin, TX. Results indicate that the performance of LIDs is sensitive to LID configurations, application areas, and storm event characteristics, suggesting the need for studies on spatial optimization of LIDs and critical storm events to maximize the utility of LIDs. The LID modules offer a comprehensive modeling framework that explicitly simulates the water quantity processes of the LIDs considering landscape heterogeneity.     

井渠结合灌区信息管理与控制系统

为满足井渠结合灌区信息化管理与科学用水监管的需要,基于无线传感器网络,采用MapWindow开源地理信息系统组件与 MySQL数据库,设计一种井渠结合灌溉管网输水灌溉信息管理与控制系统。应用结果表明,该系统的网络连通性和抗干扰性较好,软件部分运行稳定且支持多操作系统,可实现井渠结合灌区水资源联合调度、远程无线监控和信息化管理。     

Parameter optimization of distributed hydrological model with a modified dynamically dimensioned search algorithm

A modified version of the dynamically dimensioned search (MDDS) is introduced for automatic calibration of watershed simulation models. The distinguishing feature of the MDDS is that the algorithm makes full use of sensitivity information in the optimization procedure. The Latin hypercube one-factor-at-a-time (LH-OAT) technique is used to calculate the sensitivity information of every parameter in the model. The performance of the MDDS is compared to that of the dynamically dimensioned search (DDS), the DDS identifying only the most sensitive parameters, and the shuffled complex evolution (SCE) method, respectively, for calibration of the easy distributed hydrological model (EasyDHM). The comparisons range from 500 to 5000 model evaluations per optimization trial. The results show the following: the MDDS algorithm outperforms the DDS algorithm, the DDS algorithm identifying the most sensitive parameters, and the SCE algorithm within a specified maximum number of function evaluations (fewer than 5000); the MDDS algorithm shows robustness compared with the DDS algorithm when the maximum number of model evaluations is less than 2500; the advantages of the MDDS algorithm are more obvious for a high-dimensional distributed hydrological model, such as the EasyDHM model; and the optimization results from the MDDS algorithm are not very sensitive to either the variance (between 0.3 and 1) for randn′ used in the MDDS algorithm or the number of strata used in the Latin hypercube (LH) sampling.     

The groundwater modeling tool for GRASS (GMTG): Open source groundwater flow modeling

Geographic Information Systems (GIS) are used to store, manipulate and visualize both spatial and non-spatial data. Because of their data manipulating capabilities, GIS have been linked to different simulation models in different research areas and are commonly used for both surface and ground water modeling. Unfortunately this has been done mainly with proprietary GIS which are expensive and which do not provide access to their source code thus making them hard to customize. In order to overcome these problems, a module was created in the Open Source Geographic Resources Analysis Support System (GRASS) GIS to integrate it with the finite difference groundwater flow model MODFLOW, to take full advantage of the GIS capabilities. The results obtained with this module, when compared to those obtained with an existing MODFLOW pre and post-processor show that it can be used to develop groundwater flow models using uniform grid spacing on the horizontal plane. This module provides a tool for groundwater flow modeling to those users who cannot afford the commercially available processors and/or to those who wish to develop their models within a GIS.     

Large-scale analytical water quality model coupled with GIS for simulation of point sourced pollutant discharges

Mathematical modeling is an important tool for water quality studies, and the integration of water quality models with geographic information systems (GIS) is very useful for information extraction and for results interpretation. In this context, this work presents the development of a water quality model coupled with GIS (MapWindow GIS) for representing impacts of point-sourced pollutants released with distinct durations under different flow scenarios, allowing a systemic view of the entire basin, and capable of being used with low data availability. The model is called SIAQUA-IPH and uses a pollutograph convolution scheme to represent multiple discharges and confluences in the basin, based on analytical solutions of the longitudinal advection-dispersion equation. Operational tests presented a full operational performance from all technical solutions adopted, and a representation of plumes considered satisfactory in comparison to observations. Additionally, a simple sensitivity analysis is presented, that gives useful insights about the model application.     

A GIS-based modeling approach for implementation of sustainable farm management practices

Few agricultural producers utilize the true analytical power of GIS and computer simulation models, partly because the loose linkages developed to-date between GIS and most public-domain modeling software are extremely cumbersome to use. The integrated system (EPIC–View) developed in the study allows the integration of a comprehensive hydrologic–crop management model (EPIC) with a desktop GIS to function as a planning tool aimed at implementing sustainable farm management practices. The use of GIS makes possible the integration of diverse spatial data into a comprehensive spatial database. EPIC–View is applied to simulate nitrogen (N) dynamics under conventional and minimum tillage conditions of a field located in Caddo County, Oklahoma. In general, the overall N balance obtained under minimum tillage is better than the balance obtained under conventional tillage over a 5-year model run. Unexplained losses of N averaged 9.55% and 4.2% of the gain in N under conventional and minimum tillage respectively. The integrated modeling system holds immense potential as a farm management tool. Various components of a sustainable agricultural system including irrigation management, crop management, soil management, and pest management, can be efficiently managed. This approach could make farms more economically viable and ecologically sound.     

报刊业地理信息系统设计与实现

本文设计了以空间信息为整合和分析工具的报刊业地理信息系统,介绍了系统建设的背景和意义,进行了业务需求分析和模块设计,并基于构件技术和网络服务WebServices技术进行了系统功能设计和实现。该系统为报刊业的空间信息管理与应用、空间分析、决策支持、业务状况改善等提供了一种可行的解决方案。最后探讨了系统的进一步研发方向。     

基于GIS的空间过程模拟建模方法研究

ＧＩＳ空间过程建模分析功能是ＧＩＳ走向广泛应用的基础,为了实现这一目标,不公要求ＧＩＳ的数据模型能够充分表达过程模型所需的基本数据集和模拟模模型的输出数据集,还要求ＧＩＳ提供更加丰富的空间分析功能,尤其是多时相空间分析功能。     

A GIS-based software for forecasting pollutant drift on coastal water surfaces using fractional Brownian motion: A case study on red tide drift

For ocean pollution emergencies, decision-makers need to quickly know the location of the pollutant for quick assessment and response strategies. In this study, an integrated operational forecasting model coupling a non-Fickian particle-tracking diffusion model based on fractional Brownian motion and geographic information system (GIS) has been developed to implement an operating system for pollutant drift forecasting. The software was developed in C# and C++ language using ArcGIS Engine functions which provides improved visualization and user-friendly and automatic tools for simulation in a geographically referenced environment. The capabilities and effectiveness of the developed software were illustrated by predicting red tide drift through calibration with field observations. This visualized operational forecasting software provides a quick and easy deployable tool for decision-makers in quick response to emergency ocean pollution events.     

Tabu-based GIS for solving the vehicle routing problem

Besides being a hard combinatorial problem, the VRP is also a spatial problem. Hence, effective decision making in this field strongly requires the integration of GIS and optimization systems (GIS-O). This article integrates GIS and optimization tools for solving the vehicle routing problem with loading and distance requirements (DCVRP). A general outline of the multi-step integration is pointed out showing the interaction of the GIS and the spatial optimization according to the loose coupling strategy. The computational performance of the TS-VRP algorithm for the DCVRP turned out to be quite efficient on both computation time and solution quality. The Tunisian case study well illustrates the incentive behind using such a spatial decision support system that allows the management of the problem from the data acquisition to the visualization of possible simulation scenarios in a more realistic way.     

IDL在分布式GIS系统中的应用研究*

以新型的面向图形对象、基于矩阵的交互式数据处理语言(IDL),与空间数据引擎(SDE)结合来构建分布式GIS应用,既发挥了IDL在空间数据处理、三维显示方面的长处,又利用了SDE在空间数据管理方面良好的性能及安全性,同时避免了在购买专业GIS开发组件许可证上的巨额投入,在性能和开发成本之间做到了合适的平衡,是一种经济可行的应用方案.     

基于ArcGIS的扎龙湿地三维显示模块的开发研究

论文主要以扎龙湿地信息查询管理系统的设计和应用为背景,以ESRI公司研制的GIS软件ArcGIS8.1为开发平台,采用COM(组件对象模型)技术,结合面向对象的编程语言VisualBasic对ArcGIS提供的控件SceneViewerCtrl和开发对象接口ArcObjects进行二次开发,建立了扎龙湿地三维显示模块,实现了对扎龙湿地地形地貌的三维显示以及三维漫游等功能。在此基础上,为了能够使三维显示模块对湿地的调洪蓄水提供决策上的支持,加入了洪水演进仿真模块,初步实现了洪水的动态演进,解决了传统二维显示的局限性,为与专业水流动模型的结合,实现真正意义上的洪水演进仿真奠定了基础。     

通信网络仿真软件应用研究

通信网络仿真软件以其建模速度快、仿真结果精确、成本低等优势,已经成为科研工作者广泛采用的研究方式。文章对目前的通信网络仿真软件进行了研究,从商业和开源的角度入手展开介绍,并对一款商业仿真软件OPNET Modeler和一款开源仿真软件NS-2做了深入介绍。     

基于Web Service的空间信息服务研究

WebGIS已经成为目前空间信息大众化的有力工具，然而系统之间难以集成，无法互操作和空间数据共享等问题却严重制约了WebGIS的发展，GIS Web服务的出现为解决这一难题提供了全新思路。介绍了Web服务的基本概念、分析了Web服务与GIS结合的优势、探讨了GIS Web服务开发的基本原则，同时提出了一个GIS Web服务的模型，并进行了相关的实验。     

统一对象模型—对GIS融入IT的认识

The process of manufacturing tools by human being has experienced three stages material tools,energy tools and information tools. Information tools compose information system in the form of systems. Information systems are mapping of entities and relationships between them in real world. It composes of objects and relationships,objects can be classified into Facility Objects and Domain Objects, Domain Objects are inheritance and extension of Software Facility Objects ,Software Facility Objects are generalization and abstraction of Domain Objects. Information systems are digital model of the real world; the core problems of IT development are modeling the real world. The development of GIS extends the current object model,to construct a Unified Object Model with spatial property. It makes IT modeling the real world more effectually,information is organized and analyzed in the spatial framework,it will improve the unification of spatial and temporal recognition in IT and promote the development of knowledge tools. Current GIS technology is suitable for resolving the macro spatial problems,Micro GIS must be developed to solve the micro spatial problem.     

基于GIS 的区域环境噪声评价方法研究

噪声污染具有复杂的空间分布特征, 传统评价方法难以达到准确、直观的效果。以大学校园为例, 探讨了GIS 方法在区域环境噪声评价方面的应用。研究表明, GIS 方法是区域环境噪声评价理想的技术工具并具有良好的应用前景。将噪声模拟、与GIS 平台整体集成是改善区域环境噪声评价方法的重要途径。     

基于蚁群算法的GIS数据拓扑空间关系描述

GIS作为一种描述和分析现实世界的工具,数据的拓扑空间关系是其重要的基础理论问题之一。过去对GIS拓扑空间关系的描述均是基于点集拓扑学的基本理论,描述点、线、面、体间的覆盖、相邻、相交和相离等关系。文章用点集拓扑学研究GIS数据的搜索空间和真值空间的度量空间性质,确认搜索空间与真值空间映射的连续性,用蚁群算法在搜索空间搜索GIS几何数据的真值近似值,以求出点、线、面、体的最优几何解。实验结果证明,基于蚁群算法描述GIS数据拓扑空间的关系克服了传统方法的局限性,更具有灵活性。