Xinhao Wang

Land allocation based on integrated GIS-optimization modeling at a watershed level

Results of a watershed optimization model that specifies the future amount of land for each land use type at a sub-area level are incorporated into a GIS-based spatial allocation model to provide specific location recommendations based on existing land use, slope, distance to surface water and conversion preference. Thus, more detailed interpretation and implementation of optimal development scenarios can be obtained. This integrated approach was applied in Lake Erhai basin, China. This prototype land allocation system combines the strength of optimization modeling and GIS. A decision maker knows where and what type of land use changes should be made to achieve an environmental and economic sustainable future. That is, the modeling results provide support for answering questions of “what should I do?” and “how do I do it?” in land use planning and decision-making.

A comparison of drainage networks derived from digital elevation models at two scales

Automated generation of drainage networks has become increasingly popular with powerful analytical functions in geographic information systems (GIS) and with the increased availability of digital elevation models (DEMs). This paper compares drainage networks derived from DEMs at two scales, 1:250 000 (250K) and 1:24 000 (24K), using various drainage parameters common in hydrology and geomorphology. The comparison of parameters derived from the 250K DEMs with those from the 24K DEMs in 20 basins ranging from 150 to 1000 km2 in West Virginia shows that the goodness-of-fit between parameter estimates based on the DEMs varies. Results clearly show that superior estimations are produced from the 24K DEMs. Better estimates can be obtained from the 250K DEMs for stream length and frequency parameters than for gradient parameters. However, the estimation of the mean gradient parameters based on the 250K DEMs seems to improve with increasing terrain complexity. Finally, basin size does not strongly affect the accuracy of parameter estimates based on the 250K DEMs.

Integrating GIS, simulation models, and visualization in traffic impact analysis

Planners have a long history of using Geographic Information Systems, simulation models and three-dimensional (3D) visualizations in research and practice projects. Although some have successfully integrated GIS and simulation modeling or GIS and computer visualization, few have met the challenge of integrating the three technologies into one system in order to support planning and decision-making. In an effort toward reaching this goal, a prototype traffic impact analysis system has been developed. Automobile traffic and travel speed are predicted with a volume/capacity ratio model. Carbon monoxide (CO) concentrations along roadways are calculated using the US Environmental Protection Agencys CAL3QHC model. GIS is used to prepare data and execute the models and present the modeling results in a geographic context. A series of 3D models of street segments and buildings along the highway are developed and subsequently integrated with simulation results to allow a geo-referenced 3D presentation, including animations of driving experiences. This study documents the benefits and challenges of integrating the technologies.

Voucher Recipient Achievement of Improved Housing Conditions in the US: Do Moving Distance and Relocation Services Matter?

When householders are vouchered-out from distressed, federally subsidised private developments in the US and receive moderate relocation counselling, does that counselling lead to a more intensive housing search, longer-distance moves and higher levels of housing satisfaction ? Multiple regression analysis was applied to a data-set containing survey and geographical information (for example, distance moved, median neighbourhood income level) for 201 voucher recipients in 4 cities. The analysis was used to determine if the use of relocation counselling services (as well as the type of services utilised) and distance moved helped to explain variations in housing satisfaction. Those who used counselling services were in fact more likely to be satisfied with their new home than were those who were unaware of these services. However, those who were aware of the services but did not use them fared as well as householders who used them. Counselling to help in dealings with landlords was the most influential type of relocation assistance vas à vis housing satisfaction. The distance householders moved played an insignificant role in the analysis. This finding undoubtedly reflects the fact that voucher recipients sought to remain in or close to their original neighbourhood to be near friends and relatives and familiar bus lines, and the fact that better housing units offering a greater sense of safety were available in the same neighbourhood or in neighbourhoods adjacent to the vouchered-out development. Implications for HUDs vouchering-out policy are discussed.

A cross-scale comparison of drainage basin characteristics derived from digital elevation models

The feasibility of using small-scale digital elevation models (DEMs) to extract various drainage basin characteristics was evaluated by comparing basin parameters derived from the 1:250 000 DEMs with those from the 1:24 000 DEMs. Twenty basins ranging approximately from 150 km2 to 1000 km2 in West Virginia, a geologically complex region, were examined in this study. The basin parameters examined included those commonly used in hydrology and geomorphology such as elevation, slope, stream length, drainage density, relief ratio and ruggedness number. Our results suggested that the 1:250 000 DEMs can provide accurate estimates for elevation-based and stream-length-based basin parameters, but not for slope-based parameters. After examining the differences between the DEM-derived basin parameters from the two different scales, we found that the performance of the 1:250 000 DEMs was not significantly influenced by basin size, while terrain complexity seems to be an important factor of accuracy of the estimated basin parameters. Copyright

GIS-ROUT: a river model for watershed planning

Previous studies have shown that significant environmental changes are the result of human activities such as urbanization occurring at the spatial scale of landscapes. The challenge faced by many planners today is how to understand such relationships in order to support integrated watershed planning and management. Although many mathematical models have been developed to simulate the chemical transport process in a river, few are actually used in watershed assessment and management. Recently, incorporating analytical models into GIS platforms has emerged as a promising research area attracting planners and other resource managers. In this paper we present a GIS-based river water quality model (GIS-ROUT) to predict chemistry changes in river water as a result of sewage discharge changes in a watershed. Integration of spatial data, GIS, and analytical models in GIS-ROUT makes it possible to examine the dynamic linkages between water quality and human activities in a watershed. Furthermore, the user-friendly interface of the model allows its users to concentrate on the planning issues, such as examining the “What if…” questions related to different development scenarios. The study not only contributes to the application of GIS and water quality models in planning, but it also provides a comprehensive view of the watershed that can help government agencies and other stakeholders to make informed decisions.

Determining the influence of habitat and chemical factors on instream biotic integrity for a Southern Ohio watershed

The relative influences of water quality and in-streamhabitat on receiving water biology were investigatedin the Little Miami River, Ohio, a national and statescenic river located in the southwest corner of thestate. Monitored sample data for water chemistry,habitat, invertebrates and fish were obtained fromfederal and state sources and integrated via ageographical information system (GIS), using a uniquestream segmenting system. Locations and flowinformation for municipal wastewater treatment plants(WWTPs) were also integrated into the system. Therelative importance of water chemistry and habitat onbiological sample information was determined usingmultivariate forward stepwise regression. Theprincipal environmental factors that influencedbiological responses were in-stream habitat andpercent cumulative WWTP effluent at mean flow. Cumulative WWTP effluent at low flow dilution,nutrients and total toxic units from metals andammonia did not correlate with biological responses(e.g. number of mayfly species, invertebrate communityindex (ICI), number of fish species and index ofbiotic integrity (IBI)). We found the GIS-based datamethods to be highly useful for understanding theprincipal processes that guide receiving water health.

The geographic concentration of housing vouchers, Blacks, and poverty over time: a study of Cincinnati, Ohio, USA

Using data from the US Department of Housing and Urban Development (HUD) concerning Housing Choice Voucher (HCV, formerly called Section 8) recipients, the authors provide a spatial analysis in Cincinnati, Ohio, USA. ‘Hot spot’ analysis is utilized to detect areas with significant densities of voucher recipients compared with the surrounding environs. Results show that the implementation of Cincinnatis HCV program between 2000 and 2005 in conjunction with public housing transformation has not led to a greater dispersion of voucher recipients and either poverty or racial deconcentration. Many HCV households remain concentrated in hot spots. The implications for US low-income housing policy are discussed.

Assessing library performance with GIS and building evaluation methods

Purpose – The purpose of this article is to report on the methodological approach taken in a project which was to create a Facilities Master Plan for the Public Library of Cincinnati and Hamilton County in the United States. Libraries are changing drastically: they function as community centers, where programs and classes are held; they provide access to the internet to socio‐economically weaker groups; and they accommodate the needs of different age groups, such as children, teens, adults and seniors.Design/methodology/approach – Innovative in the approach to the project is the combination of geographic information system (GIS) and building performance evaluation (BPE) methods. This project assigned comprehensive scores for each of the libraries and grouped them into groups of high, medium and low performing libraries. The rankings are based on composite scores made up of eight weighted performance indicators: staff survey, facility evaluation, service area, usage, building, site, staffing output, and ca...

A hybrid GIS-supported watershed modelling system: application to the Lake Erhai basin, China

Abstract In this study, a hybrid GIS-supported watershed modelling system is developed for integrated planning of water pollution control in the Lake Erhai basin, China. The system comprises a GIS-supported database, simulation/optimization models, and user interfaces developed through Arc/Info and Arc View. An inexactfuzzy multi-objective optimization model is developed for assessing a variety of system objectives and generating desired decision alternatives. It can effectively reflect uncertain, interactive and multi-objective features of the study system, and its solutions provide decision makers with a flexible decision space. The GIS technology is used for managing spatial and non-spatial data, linking models, and providing interfaces between the models and their users. The developed modelling system allows regional planners to obtain desired plans of human activities under a variety of objectives and constraints and to examine consequences and impacts resulting from alternative management practices.