While much emphasis has been placed on the importance of hydrology as a driving force for wetlands, few small stream drainage networks have been mapped. Light Detection and Ranging (LiDAR) data can provide very high-precision topographic maps over large areas, and have been used to extract drainage networks in forested areas, vineyards, and high mountain pastures. The study objective is to reconstruct the ditch network from LiDAR data in wetlands estimating the required accuracy for assessing their functions. Several Digital Terrain Models (DTMs) have been derived from LiDAR data with different point densities, ranging from 4 to 1 point/m² with four interpolation methods. Then, the drainage network has been extracted from each DTM using an object-based image analysis. This approach has been applied in wetlands located near the Mont-Saint-Michel, France. Results have been validated with field data. They show that the quality of the drainage network map significantly depends primarily on the LIDAR data precision (point-density) and, to a lesser extent, on the interpolation method used. A minimum precision of 2 points per m² is required to properly represent the ditch network. The Nearest Neighbor interpolation method provides the best results and in the shortest computation time.
Monitoring Volcanic Ash provides early warnings of Hazardous Atmospheric ConditionsVolcanic ash is a recurring impediment to normal air-traffic operations in Europe, Asia and South America due to potential jet engine damage caused by the razor-sharp particles in dense ash plumes. A notable example is the 2010 eruption of the Eyjafjallajökull volcano in Iceland that shut-down air traffic throughout Western Europe for seven days, with intermittent closings necessary as new ash plumes continued to enter the...
Water UK’s report on ‘Lessons learned from summer floods 2007’ highlights a need for better flood forecasting tools that Wallingford Software’s InfoWorks CS, RS and FloodWorks are perfectly aligned to meet. The water industry’s trade body set up a review after the devastating flooding that hit many parts of the country and overwhelmed the Mythe water treatment works in Gloucestershire, leaving thousands of Severn Trent Water’s customers without tap water for days. Emergency services battled successfully to...
Introduction
Engineers are nowadays expected to not only be skilled in technical matters, preparing calculations and designs, but also to know far more about risk analysis than ever before. In almost all aspects of engineering, risk analyses are now commonplace, with many of the design codes used based on statistical analyses. In the fields of river and coastal engineering it is nowadays expected that risk analyses will be undertaken as a standard element of a project. Part of this analysis is to determine the...
Abstract
The biomass carbon (C) stock of forests is one of key parameters for the study of regional and global carbon cycles. Literature reviews shows that inventory-based forest C stocks documented for major countries in the middle and high northern latitudes fall within a narrow range of 36–56 Mg C ha−1 with an overall area-weighted mean of 43.6 Mg C ha−1. These estimates are 0.40 to 0.71 times smaller than those (61–108 Mg C ha−1) used in previous analysis of balancing the global carbon...
The International Joint Commission has recently completed a five-year study (2000–2005) to review the operation of structures controlling the flows and levels of the Lake Ontario – St. Lawrence River system. In addition to addressing the multitude of stakeholder interests, the regulation plan review also considers environmental sustainability and integrity of wetlands and various ecosystem components. The present paper outlines the general approach, scientific methodology and applied management considerations of...
ABSTRACT: Wetland rapid assessment methods (RAMs) can provide a cost effective, scientifically defensible estimate of wetland and riparian condition for use in ambient and project monitoring in resource management
and regulatory programs. Those who have chosen to develop a RAM to assess wetland and riparian condition are faced with a range of issues and important choices that they must make throughout the development process. This paper is intended as a practical guide to RAM development. Six basic stages in the...
The island of Jamaica is located in the Caribbean Archipelago, 90 miles south of Cuba, 600 miles south of Florida and 100 miles south-west of Haiti. It has a population of 2.6 million, 800,000 of whom live in the metropolitan area of the capital, Kingston. The island is mountainous, with a distinct east-to-west ridge and a dramatic relief change in the east.
Like the rest of the region, Jamaica suffered the impact of tropical cyclones in 2005. Warmer waters in the Gulf of Mexico have created a series of...
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In recent years the availability of accurate Digital Terrain Data has improved and it is now reasonably priced. This has meant that the network modeler can use the data as a tool to help develop accurate models. Digital Terrain Data can be obtained by many methods, from ground surveys to airborne LiDAR.
Over the last few years there have been many papers and discussion on overland flow routing, and Digital Terrain Models (DTM's) are a vital part of any method of predicting...
Abstract In the United States, the regulatory approach to wetland protection has a traditional focus on size as a primary criterion, with large wetlands gaining significantly more protection. Small, isolated wetlands have received less protection; however, these wetlands play a significant role in the maintenance of biodiversity of many taxonomic groups, including amphibians. An important question for directing conservation and management efforts for amphibians is whether size is a useful criterion for regulatory...
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The problem
Water companies typically keep their network asset data either in a GIS or in a number of different files of different formats and ownership; some companies use a combination of the two. The management of such data repositories is often an ongoing headache for water engineers, especially at the time of data entry – import into the database– and at the point of using the data – exporting the data from the database. These problems usually stem from the following...
This study presents a comparative evaluation of the prognostic meteorological Fifth Generation NCAR Pennsylvania State University Mesoscale Model (MM5) using data from the Northeast Oxidant and Particle Study (NE-OPS) research program collected over Philadelphia, PA during a summer episode in 1999. A set of model simulations utilizing a nested grid of 36 km, 12 km and 4 km horizontal resolutions with 21 layers in the vertical direction was performed for a period of 101 h from July 15, 1999, 12 UTC to July 19,...
ABSTRACT
This paper presents the development of a decision support system (DSS) for flood warning and instantiation of restoration activities in two urban areas, the Liguria Region in Italy and the Greater Athens catchment in Greece, with the potential of extension to other locations with similar flooding problems. The tool is designed to work at the centre of a set of meteorological and hydrologic/hydraulic forecast models together with telemetric data acquisition networks. The study reveals the complexity and...
Introduction
The flow variations in sewers have been modelled for several years with a comparatively high degree of accuracy as far as the diurnal variations and responses to climatic conditions are concerned. However, until comparatively recently the variations in flow due to fluctuations in groundwater levels, soil storage capacity and wetness of the catchment have only been modelled in basic terms. For the past decade it has been possible to use runoff models that respond to the increasing wetness of the...
ABSTRACTUrban stormwater often contains high levels of traffic-generated metal elements and particulates. These constituents are transported by stormwater runoff to surficial soils, drainage systems and receiving waters. This paper summarizes the in-situ field-scale performance of a passive treatment system called a partial exfiltration trench (PET) for source control of these constituents. For stormwater runoff infiltrated into the PET media, treatment occurs primarily by sorption and filtration. Previous...
Traditionally the use of soil improvers in agriculture is aimed at the restoration of the organic substance removed from the agro-ecosystem by crops. The addition of humus, as replacement for the portion gradually mineralised by the micro-organisms of the soil, leads to the conservation of its fertility under many point of view: physical (e.g. porosity, drainage, aeration), chemical (availability of nutrients) and biological (intensity of the microbial activities) fertility of the soil itself. In such a respect,...
Air dispersion modeling has been evolving since before the 1930s. Over the last 15-25 years, strict environmental regulations and the availability of personal computers have fueled an immense growth in the use of mathematical models to predict the dispersion of air pollution plumes. Beychok`s recently published book, `Fundamentals Of Stack Gas Dispersion`, details the evolution of the widely used Gaussian air dispersion models and their inherent assumptions and constraints.
Unfortunately, many users of such...
Introduction Sustainability or `sustainable development` has become a term which is frequently applied to land use and social planning and resource issues. Sustainability is a concept which draws attention to development practices which can degrade natural ecosystems and deplete natural resources. If development is defined broadly to include any cultural activity, then sustainable development may be defined as any practice that meets the needs of the present population without compromising the ability of future...
Fuel contaminants are generally nonhalogenated. Information presented for nonhalogenated VOCs and nonhalogenated SVOCs may also be appropriate for many of the fuel contaminants presented in this subsection.
Contamination by fuel contaminants in the unsaturated zone exists in four phases: vapor in the pore spaces; sorbed to subsurface solids; dissolved in water; or as NAPL. The nature and extent of transport are determined by the interactions among contaminant transport properties (e.g., density, vapor pressure,...
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