Integration of a GIS and a complex three-dimensional hydrodynamic, sediment and heavy metal transport numerical model

Hong Kong Research Grants Council [PolyU 5143/04E]; Hong Kong Polytechnic University [G-YD93]The paper presents an integration of a geographic information system (GIS) and a complex three-dimensional hydrodynamic sediment and heavy metal transport numerical model. The integration overcomes the two-dimensional constraint of conventional GIS by supplementing advance tools for three-dimensional, dynamic visualization. The application of a GIS-based interface module together with the three-dimensional, dynamic display tools enhances communication of relationships and trends of hydrodynamic and pollutant transport simulation in both spatial and temporal context, and thus promotes better coastal water quality planning and management. Model functionality includes input data viewing and editing, mesh grid configuration, and result interpretation. The functionality of the GIS-model integrated system is illustrated through a case study on the Pearl River Estuary (PRE). (C) 2008 Elsevier Ltd. All rights reserved

GIS como ferramenta de ajuda pré- e pós-processamento de modelos hidrodinâmicos. Aplicação ao estuário do Guadiana

Dissertação de mest., Geomática (Análise de Sistemas Ambientais), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2013The main objective of this work is to develop GIS based techniques to aid the setup of hydrodynamic models and to improve model results. This dissertation analyzes well-known GIS methods and proposes new ones to prepare and process estuarine model data. Estuarine hydrodynamic models require management of large quantities of georeferenced information. A Geographic Information System (GIS) can help to store, manage, analyze and display all these data during the input and the output phases. The hydrodynamics of the Guadiana Estuary was simulated using a 2D configuration in MOHID Water Modelling System, based on a boundary fitted curvilinear grid. GIS tools were used to pre-process the model grid and bathymetry. The water domain was extracted from the orthophoto using unsupervised classification of the image based on principal component analysis of the spectral bands. The large amount of bathymetric measurement points was decreased using a spatial regular pattern (hexagons). The missing bathymetry data in some very shallow parts of the estuary were estimated from the orthophoto using correlation between existing data and spectral band values. The bathymetry data were interpolated into curvilinear grids by several different methods, including an advanced method using river straightening (transformation to the along-channel coordinate system). The finite volume model MOHID was used to test these methods and evaluate the associated improvements. The model results were in good agreement with the observations under well-mixed conditions. Including the bathymetry estimated from orthophoto improved the accuracy of the simulations; and using advanced interpolation methods improved the results even more. The bathymetry interpolation in the channel-oriented coordinates significantly improved the direction of the water current. Good quality of the spatial input data was critical for obtaining good model results. The use of GIS tools to produce model inputs proved to be a valuable aid to coastal hydrodynamic modelling increasing substantially the model accuracy. This dissertation is useful in both theoretical and practical fields of science: in theoretical, by analyzing and developing GIS methods to prepare and process estuarine hydrodynamic model data, in practical, by creating an improved model setup for the Guadiana Estuary, using more accurate bathymetric data and a new curvilinear grid, thus obtaining more realistic results

GIS-based modelling of agrochemical use, distribution and accumulation in the Lower Mekong Delta, Vietnam: A case study of the risk to aquaculture

In recent years, the Mekong delta has been strongly developed both for agriculture and aquaculture. However, there is scope for a negative impact of agriculture on aquaculture in term of production and quality of seafood products. Specifically, the large amount of pesticides imported and used in the Mekong delta not only help agriculture purposes but can also easily enter aquatic systems and affect aquaculture. Pesticides can be transported in the environment by chemo-dynamic procedures and hydrological processes. As a result, pesticides used in agriculture become dispersed and their residues in sediment, water and biota have been detected in the Mekong delta. This study investigated the overall pesticide process including pesticide use, modelling pesticide accumulation and evaluating the potential impact on aquaculture sites for some target aquatic species. The risk of pesticides use in the Mekong delta was addressed in three stages: (1) investigating current pesticide use status in the Mekong delta; (2) modelling pesticide loss and accumulation; (3) classifying pesticide risk areas for aquaculture of target cultured species. A survey of 334 farms covering a total area of ~20,000km2 in the Mekong delta took place between 2008 and 2009. Information on pesticide types and quantities was recorded using questionnaires, and it was found that 96 pesticides in 23 groups were popularly used for agricultural purposes. Dicarboximide, Carbamate and Conazole had the highest use at ~3000, ~2000 and ~2000 g/ha/year respectively. The survey revealed an increase in pesticide use per hectare since previous surveys in the Mekong delta in 1994, 2000, and 2004. However, the highly persistent compounds (WHO classification classes II, III and IV) appeared to have reduced in use. Insecticides previously represented >50% of the total pesticides used, however, the resent survey has shown their use has decreased to ~38%.There was a parallel increase in use of fungicides from previous levels of <30% of total pesticides to more recently ~41%. The combination of pesticide information and geo-location data enabled display and analysis of this data spatially using a Geographic Information System (GIS). A pesticide loss and accumulation model was established through combination of several sub-models including sediment loss and accumulation, direct loss, and water runoff, all of which were implemented and integrated within the GIS environment. MUSLE (Modified Universal Soil Loss Equation) was used to estimate sediment loss and accumulation in the Mekong delta and the Curve Number method (CN Method) was applied to predict water runoff and discharges and flow accumulation. Modelling commenced from the first pesticide application in April, based on 4 day time-steps. All mathematical calculations run within each time step automatically reiterated in the following time step with the new input datasets. The results from fuzzy classification of the pesticide model outcomes were considered in terms of the 96hr lethal concentration (LC50) in order to classify the risk and non-risk areas for catfish and tiger shrimp culture. The sediment loss and accumulation model shows that the highest loss of sediment was in the rainy season, especially in May to October. Vegetables and short term crop areas were found be most strongly eroded. The MUSLE model showed that the highest sediment accumulation was in the hilly areas (~1066.42 tonne/ha/year); lower in riverside areas (~230.39 tonne/ha/year) and lowest in flooded paddy areas (~150.15tonne/ha/year). Abamectin was used as an example throughout this study to estimate pesticide loss and its effects on aquaculture. The results showed that pesticide loss by runoff and sediment loss is less than the loss by half-life degradation (for Abamectin specifically). Accumulation of Abamectin occurred at highest rate in May and October and decreased with time. The spatial models showed that pesticide residues concentrated in the river and riverside areas. In order to evaluate the acute toxicity impacts, three levels of water depth in ponds were modelled as culture depths for catfish and tiger shrimp. The results show that the highest risk areas for catfish occurred in May and October with ~333,000 and ~420,000 ha at a pond depth of 0.5 m; ~136,000 and ~183,000 ha at a pond depth of 1.0 m; and ~10,840 and ~19,000 ha at a pond depth of 1.5 m. Risk areas for catfish mainly concentrated at the riverside and in part of the coastal areas. For tiger shrimp, the risk periods during the year were similar to those found for catfish. The highest risk areas for shrimp were ~648,000 and ~771,000 ha at 0.5 m pond depth; ~346,000 and ~446,700 ha at 1.0 m pond depth; and ~185,000 and ~250,000 ha at 1.5 m pond depth. Overall, deeper ponds reduced the risk. This study has developed a method to evaluate the negative impact of input pesticides to the environment from agricultural use related to fluctuation of aquaculture risk areas. The research indicates the potential relationship between pesticide input and the risk areas for aquaculture. The model has several significant uses: 1) it can provide information to policy makers for a more harmonized development of both aquaculture and agriculture in the Mekong delta in the future, 2) it provides data for aquaculture investment analysis to decrease the hazards caused by pesticide impacts, and 3) it provides a model capable of application to wide field scenarios and suitable for any pesticide type

The Influence of Coastal Wetlands on Hurricane Surge and Damage with Application to Planning under Climate Change

Coastal storm surges from hurricanes are one of the most costly natural disasters in the United States (US). Current research arguably indicates a mean sea-level (MSL) increase due to global warming, as well as an increase in damages caused by hurricanes under climate change. The objectives of this research are: 1) to develop a framework that integrates Geographical Information Systems (GIS) with hurricane storm surge numerical models; 2) to quantify the uncertainty derived from coastal land cover spatial data on hurricane storm surge; and 3) to investigate the potential impacts of SLR changes on land cover to hurricane storm surge and coastal damages. Numerical analysis is an important tool for predicting and simulating storm surges for coastal structure design, planning and disaster mitigation. Here we proposed a framework to integrate Geographical Information Systems (GIS) with computational fluid dynamic (CFD) models used to simulate hurricane storm surge. The geodatamodel "Arc StormSurge" is designed to store geospatial information for hurricane storm surge modeling and GIS tools are designed to integrate the high performance computing (HPC) input and output files to GIS; pre-process geospatial data and post-process model results, thereby, streamlining the delineation of coastal flood maps. Georeferenced information of land cover is used to define the frictional drag at the sea bottom and to infer modifications to the momentum transmitted to the water column by the winds. We investigated uncertainties in the surge response arising from land cover for Texas central bays considering several land cover datasets. The uncertainties were quantified based on the mean maximum surge response and inundated area extent. Considering projected SLR, wetland composition and spatial distribution are also expected to change with coastal environmental conditions. Our results showed that wetland degradation by SLR increased the mean maximum surge for coastal bays. Direct damage to buildings and businesses was also significantly increased by the loss of wetlands due to SLR. Here, we demonstrated the importance of considering the effects of land cover and SLR to hurricane storm surge simulations for coastal structure design, floodplain delineation or coastal planning

Ferramenta de suporte ao projeto de sistemas flexíveis de transporte público de passageiros

Tese de Doutoramento em Engenharia Industrial e de Sistemas.As áreas rurais, com densidades populacionais baixas, apresentam desafios à mobilidade das suas populações. Os serviços de transporte público regular têm-se mostrado ineficazes e ineficientes levando os operadores de transporte coletivo a reduzir a sua oferta e a diminuir a qualidade do serviço oferecido. Em alternativa aos serviços regulares de transporte, alguns estudos têm vindo a mostrar as vantagens da implementação de sistemas de transportes flexíveis, em particular, transportes a pedido (DRT - Demand Responsive Transport). No entanto, os principais resultados observados nos estudos realizados apontam para a existência de várias dificuldades para o sucesso dos DRTs (aspetos legais, organizacionais, financeiros, etc.), assim como para a inexistência de ferramentas de apoio capazes de auxiliar os decisores nas etapas do planeamento estratégico e tático, antes mesmo de proceder à sua implementação. No sentido de minorar ou colmatar as lacunas referidas, esta tese pretende contribuir para uma discussão abrangente destes sistemas de transporte e propor uma nova ferramenta de suporte ao projeto de sistemas DRT. A ferramenta proposta integra um sistema de apoio à decisão (SAD) concebido para estimar o desempenho operacional de diferentes configurações a implementar, permitindo optar pela melhor solução encontrada. O SAD é suportado por um modelo de simulação microscópica do funcionamento do sistema, e inclui métodos de solução para diferentes variantes do problema de otimização de rotas e escalas encontradas neste tipo de serviços de transporte, para além de uma framework para a avaliação da sustentabilidade das soluções. Na validação do SAD desenvolvido, utilizou-se um estudo de caso português. Os resultados dos testes efetuados permitiram evidenciar as potencialidades da ferramenta proposta. Adicionalmente, a avaliação da sustentabilidade da solução permitiu identificar a difícil sustentabilidade financeira deste tipo de sistemas, mas também as suas vantagens em termos sociais e ambientais que poderão justificar a sua adoção.Rural areas with low population densities, present challenges to mobility of their populations. The regular public transport services have proved quite ineffective and inefficient leading transport operators to reduce their supply and their services quality. As an alternative to regular services, some studies have come to show the advantages of the implementation of flexible transport systems, as demand responsive transport (DRT). However, the main results obtained in the studies scope point both to the existence of different types of difficulties to the DRTs success (legal, organizational, financial aspects, etc.), and the lack of supporting tools that can assist decision makers in both strategic and tactical planning, even before proceeding to implement. In order to overcome these shortcomings, this thesis intends to discuss broadly these transport systems and to present a new tool to support the design of DRT systems. The proposed tool integrates a decision support system (DSS) specifically designed to assess the operating performance of different alternative system configurations to be implemented, allowing to choose the best solution found. The DSS is supported by a microscopic simulation model of the system operation, and even includes solution methods for different variants of the vehicle routing problem found in this type of transportation services, furthermore a framework to evaluate the solutions sustainability. To validate the developed DSS, we used a Portuguese case study. The test results allowed highlighting the DSS potentialities. Additionally, the solution sustainability assessment identified the hard financial self-sustaining of this type of systems, but also their advantages in both social and environmental impact that will probably be sufficient to justify its implementation.Fundação para a Ciência e Tecnologia SFRH/BD/60776/2009