Assessment of an ASTER-generated DEM for 2D hydrodynamic flood modeling

Flood modeling often provides inputs to flood hazard management. In the present work we studied the flooding characteristics in the data scarce region of the Lake Tana basin at the source of the Blue Nile River. The study required to integrate remote sensing, GIS with a two-dimensional (2D) module of the SOBEK flood model. The resolution of the topographic data in many areas, such as the Lake Tana region, is commonly too poor to support detailed 2D hydrodynamic modeling. To overcome such limitations, we used a Digital Elevation Model (DEM) which was generated from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image. A GIS procedure is developed to reconstruct the river terrain and channel bathymetry. The results revealed that a representation of the river terrain largely affects the simulated flood characteristics. Simulations indicate that effects of Lake Tana water levels propagate up to 13 km along the Ribb River. We conclude that a 15 m resolution ASTER DEM can serve as an input to detailed 2D hydrodynamic modeling in data scarce regions. However, for this purpose it is necessary to accurately reconstruct the river terrain geometry and flood plain topography based on ground observations by means of a river terrain model.     

基于流域GIS空间建模的雨洪模拟方法

基于多层次GIS空间分析模型技术,系统地建立了从流域雨洪过程相关影响因子栅格化处理到产汇流过程模型的集成化模拟方法,首次实现了对流域内任意栅格单元内河道断面的径流过程线的可视化测算。同时还对于模型中单元水流长度与河道单元流速率定方法进行了优化改进。实例分析结果表明:模型结构更为严谨、参数设置更为科学,改进的技术方法对于福建汀江十年一遇洪水场次的模拟结果精度有明显提高,能够满足相关海绵城市规划应用需求。     

浅析基于GIS技术的洪水灾害评估及其实现方法

针对洪水灾害评估的特点,将GIS技术与RS技术相结合,根据数字高程模型DEM提供的三维数据和遥感影像数据,运用GIS的空间分析功能来预测、模拟河流域洪水淹没场景,结合属性数据进行洪水灾害评估,并对此系统的实现方法进行对比评价。     

Hydrogeomorphological mapping in assessing ground water by using remote sensing data — A case study in lehra gaga block, sangrur district, Punjab

The paper presents the results of hydrogeomorphological mapping using IRS-IB LISS II data and evaluation of ground water prospects of each hydrogeomorphological unit in the Lehra Gaga block of Sangrur district, Punjab. The major geomorphic units identified in the area are, alluvial plain, sand dunes, palaeo channels and the Ghagar flood plain. The study area being part of alluvial plain has good to excellent ground water prospects. Field observations showed that ground water occurs under both confined and unconfined conditions with water table at shallow depth. The area on either side of the Ghagar river and along the major canals (about 46% of the total geographical area in the block) have good quality of ground water and is suitable for irrigation, whereas the water quality is marginal (sodic) in 52 per cent area of the block..     

Hydromorphology of a part of Azamgarh and Ghazipur districts,Uttar Pradesh

Hydrogeological studies in the Quaternary alluvial plain of a part of Azamgarh and Ghazipur districts, using air photos on scale 1:60,000 indicate the presence of five hydromorphic units namely, Alluvial upland, older alluvial plain of Mangat-Besu, older flood plain of Ganga—Gomti, youngest terrace of Ganga—Gomti and present flood plain of Ganga-Gomti. From the groundwater point of view older flood plain of Ganga—Gomti is the most promising hydromorphic unit. Abandoned channel of river Ganga offers favourable site for deep groundwater exploration with high potentiality. Chemical quality of shallow and deep aquifers is suitable for irrigation and other purposes.     

Surface and subsurface evidence of neotectonics and the aquifer disposition in central gangetic alluvial terrain of Kanpur-Unnao region in Uttar Pradesh,India

Both surface and subsurface evidences exist along the longitudinal section of the Ganga river in Kanpur-Unnao region of Central Ganga Plain indicating the effect of tectonic subsidence. While the surface evidences are discontinuous chain of high uplands with escarpments on the southern bank of the Ganga river and the wide flood plain on the northern side, the subsurface evidences are in terms of sudden deepending of the granitic basement towards north followed by deposition of coarse sand and gravel forming thick aquifers in the close vicinity of present channel of the Ganga river. The petrological examination of the aquifer material also indicates that the material has been derived from a deformation zone.     

水库移民GIS辅助决策支持系统的设计和实现

空间决策支持系统(Spatial Decision Support System SDSS)作为一个新兴科学技术领域,以地理信息系统(GIS)和决策支持系统(DSS)为基础,以解决生产实践问题为目标,目前已经被广泛应用于水利、交通、农业等行业。本文主要介绍应用SDSS数据和模型之间关系的思想设计和实现用于解决大型水库项目中涉及的移民安置处理问题的空间决策支持系统。系统中主要是以移民如何安置问题为基础来设计各种空间分析模型功能,其中与空间信息处理有关的几个模型主要有移民安置区选择,移民安置区环境容量分析,水库淹没损失赔偿以及移民安置区土地资源评价等问题。要解决这些生产实践问题需要对各种数据信息进行综合的宏观分析和深层次挖掘分析,结合专家知识设计可行的处理模型,并运用计算机技术和GIS技术加以实现。     

水利信息系统中的GIS技术

阐述了一种新的GIS理论成果:大型GIS与数字地球的空间数学基础理论,该理论克服了传统空间数学基础理论的不足。以该理论为理论基础并结合水利信息系统的实际需求运用GIS技术支持下矢栅结合的技术,提出了将数字栅格地图(DRG)作为专业信息系统的参考背景,用户关心的专业实体适时标注的防汛信息系统建设技术路线,该技术路线具有良好的实施前景。同时本文就系统中若干关键技术的设计与实现做了详细阐述。     

基于GIS技术的莱州湾东岸河流分形研究

应用地理信息系统(GIS)技术提取了莱州湾东岸河流信息,在此基础上运用计盒方法对莱州湾东岸的黄水河和王河水系进行了分形分析,获得了两水系的主河道河长分维数和河网分维数,并以此探讨了分维数与流域地貌和地质构造之间的相互关系。分形分析为研究区流域地貌学与水文学研究提供了一种新的研究途经。     

基于GIS/AHP集成的浙江省洪涝灾害风险评估

将GIS技术引入洪涝灾害风险评估,可以弥补传统方法评估结果空间化显示不足的缺点。本文针对浙江省洪涝灾害的发生特点,从危险性和易损性两方面选择了浙江省洪涝灾害的影响因素,包括降雨量、地形、河网密度、人口密度和耕地百分比等因子。运用GIS空间分析技术对各因子进行空间化,结合层次分析法（AHP）确定各影响因素的权重,进行浙江省洪涝灾害风险评估和制图,并基于SuperMap iObjects平台设计与开发了浙江省洪涝灾害风险评估系统。研究结果表明：浙江省发生洪涝灾害的风险普遍偏高,高风险区域位于浙北和浙东南的沿海地带,较高风险区域位于浙东、浙南和浙北地区及金衢盆地中间地区,中等风险区位于浙南的西面、浙北及浙西地区。本文分析结果可为浙江省洪涝灾害预防和管理提供决策依据。     

A Spatial Analysis System for Integrating Data,Methods and Models on Environmental Risks and Health Outcomes

Integrating data on health outcomes with methods of disease mapping and spatially explicit models of environmental contaminants are important aspects of environmental health surveillance. In this article, we describe a modular, web‐based spatial analysis system that uses GIS, spatial analysis methods and software services delivered over computer networks to achieve this end. The Environmental Health Surveillance System (EHSS) is a prototype system that is designed to serve three purposes: a secure environment for producing maps of disease outcomes from individual‐level data while preserving privacy; an automated process of linking environmental data, environmental models, and GIS tasks like geocoding for the purposes of estimating individual exposures to environmental contaminants; and mechanisms to visualize the spatial patterns of disease outcomes via Web‐based mapping interfaces and interactive tools like Google Earth.     

A note on the avulsion of Ghagghar river in the alluvial plains of Punjab and Haryana,North-West India

Ghagghar river in the alluvial plains of Punjab and Haryana, north-west India exhibits the phenomenon of avulsion in its middle and lower reaches. Study of aerial photographs shows that it has abandoned a 25 km long meander belt between Badshahpur and south of Jaswantpura which lies to the north of the present channel. The present channel course lies at a lower elevation on the flood plain away from the levee deposits which acted as an alluvial ridge.     

基于GIS的流域洪涝数字模拟和灾情损失评估的研究

非工程防洪措施是减缓洪涝灾害损失的有效方法之一。地理信息系统和遥感技术使多学科综合性的非工程防洪措施成为现实。本文从流域数据库设计、洪水预警数字模拟、河道洪水演进数字模拟、洪泛区洪水演进数字模拟、灾民疏散模型和洪水灾情损失评估等６个方面，系统阐述了地理信息系统在流域洪涝数字模拟和灾情损失评估上的应用，为今后开展同类工作提供了参考。     

Spatio-temporal analysis of land use in urban mumbai -using multi-sensor satellite data and gis techniques

The process of urbanization has induced rapid changes in the land use leading to many infrastructural and environmental problems, one of them being the frequent flooding during rains in major cities across the world. Present paper analyses the spatio-temporal variations in the urban land use of the Mithi river catchment in Mumbai and its effect on the river, its drainage and flooding events in catchment area, specifically in conjunction with the July 26, 2005 flood event in Mumbai City. Multi sensor satellite data and GIS techniques have been used to generate land use/land cover at three different points of time and study variations in the Mithi river course, thus correlating the land use/cover changes vis-a-vis the hydrographic and meteorologic information for the Mithi river catchment. Results point to the adverse human-induced influences on the Mithi river and its catchment. Almost 50% reduction in river width and 70% decrease in mudlfats and open spaces have been observed. There is also a clear rise in builtup from 29% to 70% between 1966 and 2005, thus increasing the impervious surface which in turn increases run-off during major rainfall, eventually flooding the city.     

A Hybrid Spatio-Temporal Data Model and Structure (HST-DMS) for Efficient Storage and Retrieval of Land Use Information

While the incorporation of geographical and environmental modeling with GIS requires software support for storage and retrieval of spatial information that changes over time, it continues to be an unresolved issue with modern GIS software. Two complementary approaches have been used to manage the spatial and temporal heterogeneity within datasets that use a field‐based representation of the world. Some researchers have proposed new data models that partition space into discrete elements on an as‐needed basis following each temporal event, while others have focused on eliminating duplication of repeated data elements present in spatio‐temporal information. It is proposed in this paper that both approaches have merit and can be combined to create a Hybrid Spatio‐Temporal Data Model and Structure (HST‐DMS) that efficiently supports spatio‐temporal data storage and querying. Specifically, Peuquet and Duan's (1995) Event‐based Spatio‐Temporal Data Model (ESTDM) and the Overlapping R‐tree (Guttman 1984, Tzourmanis et al. 2000) are utilized to create a prototype used to store information about urban expansion for the town of Carbondale, Illinois.     

Changing Pattern of Channel Morphology of Alaknanda River in Srinagar Valley (Garhwal Himalaya), India

The Alaknanda River is the most significant parental river of Ganga and forms an 11.5 km long and 2.5 km wide valley, locally known as the Srinagar Valley. The purpose of the present study is to highlight the recent landform changes in the Alaknanda channel course after the Kedarnath disaster, 2013. The Kedarnath flood completely changed the channel morphology of the Alaknanda river. The river changed its course at Srikot, SSB and Sriyantra Tapu with lower terraces being silted by sands at Ranihat, SSB, Bhaktiyana and Sriyantra Tapu. A new depositional terrace also formed opposite to Sriyantra Tapu. New lateral channel bars, braided channels, back swamp, rapids, pools and river souls were identified in the channel course of the river. Shifting of the channel course at Chauras still remains a serious problem for the Garhwal University Chauras Campus. About 2–5 m silt was deposited on the lower terrace at SSB, and ITI. The Srikot river bed was appended to 4.60 m. Shifting of channel course remains a serious threat to the Srinagar valley. Urbanization, sand and boulders mining, construction of dam, hydrological canal, road and settlements are the prominent example of anthropogenic activities which affect the shifting channel.     

山地丘陵与平原地区城乡聚落空间分布分形特征研究

本文以河南省区域系统的不同地域单元为例,运用城镇体系研究的空间关联维数模型对山地丘陵区及平原地区城乡聚落体系空间结构进行分析,结果表明农村聚落具有与城市聚落相同的空间分布分形特征;山地丘陵城市的城乡聚落空间可达性不及平原城市;城乡聚落空间分布的乌鸦维数集中在1左右,差别不大,表明河南省作为中原地区所具有的城乡聚落空间布局的总体均衡性。基于此提出了中部农区城乡聚落空间优化、撤乡并镇、新农村社区建设应结合地域城乡聚落分布特点制定适宜的规划方案等有益的建议。     

基于GIS的贝叶斯统计推理技术在印度野牛生境概率评价中的应用

首先给出ＣＯ２倍增下遥感－光合作物产量的概念模型,之后分析未受ＣＯ２倍增的遥感－光合作物产量估测模型;在考虑ＣＯ２倍增对作物产量的影响后,对影响干物质累积的作物光合速率的模型进行修正,进而修正遥感－光合作物产量估测模型。建立ＣＯ２倍增下作物产量影响模型,求取各参数,并在ＣＯ２倍增下对我国华北地区冬小麦产量影响进行填图,表明模型的估测结果有良好的可比性。     

基于GIS的贝叶斯统计推理技术在印度野牛生境概率评价中的应用

目前,ＧＩＳ技术已被广泛应用在野生动物生境研究中。但是,作为空间数据分析和处理工具,ＧＩＳ缺乏进行启发式推理的能力。因此,与擅长于此的贝叶斯统计推理技术相结合则是解决这一问题的重要途径。以西双版纳纳板河流域生物圈保护区为试验区,综合应用ＧＩＳ技术和多元统计技术建立印度野牛生境的两个逻辑斯蒂多元回归模型：趋势表面模型和环境模型,第一个模型的自变量是位置坐标,第二个模型的自变量是一组环境因子,然后应用贝叶斯统计合并这两个模型产生贝叶斯综合模型。结果表明,贝叶斯综合模型优于环境模型,可应用于野生动物生境概率评价。     

The role of multispectral imagery in elucidation of recent channel pattern changes in middle ganga plain

The mapability of Landsat images has opened up a new potentiality for study of channel pattern changes which was earlier not so easy due to nonavailability of suitable evidences at different timespans. Middle Ganga plain covering largely the northern part of Bihar and parts of eastern Uttar Pradesh is in a slate of perpetual flux due to large scale channel migration and avulsion resulting in devastating floods. Mosaic of three Landsat images has helped to study the channel changes which have occurred since 1935. The course of the river Ganga has beeh digitised along a basal line and two dimensional coordinates are taken at as many as more than fifty sample points for studying the magnitude and direction of channel changes during 1935–1975 period. The analysis shows that the main multiple channel river Ganga is under the huge hydrostatic thrust to be shifted towards south of its basin annually at a very high rate of 100 Meter per year all along the course except at its upstream near Ghazipur and at Monghyr where the shifting is towards north. The northward bend at Monghyr may be due to the presence of the Precambrian outliers here. For the multi-and single channelld tributaries of Ganga in channel behaviour is mainly in three directions—the lower water channels in the floodplain of Ganga are shifting to the south in conformity with that of their parent stream, the tributaries in Gogra-Gandak doab are shifting towards east but the shifting of the Kosi-Mahananda group of tributaries in the eastern part of the basin is towards west These channel pattern changes thus known at the interregional scale from the Landsat images may further be integrated with the study in hydrogeomorphology and their pertinent environmental impact.