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Saturated Areas (saturated + area)

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Engineering	100%

Selected Abstracts

A research on used quantity of ground resistance reduction agent for ground systems

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 4 2010
Li-Hsiung Chen
Abstract The ground resistance reduction agent can be used to decrease ground resistance for high soil resistivity. The ground resistance decreases and the ground resistance reduction rate increases with increasing quantity of ground resistance reduction agent used. However, the ground resistance reduction effect will display the saturation phenomenon when the quantity of ground resistance reduction agent used increases to a certain level. This research discusses the quantity of ground resistance reduction agent used for ground rod. The used quantity of ground resistance reduction agent should be avoided in saturated areas to maximize the efficiency of ground resistance reduction agent use. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Using a topographic index to distribute variable source area runoff predicted with the SCS curve-number equation

HYDROLOGICAL PROCESSES, Issue 15 2004
Steve W. Lyon
Abstract Because the traditional Soil Conservation Service curve-number (SCS-CN) approach continues to be used ubiquitously in water quality models, new application methods are needed that are consistent with variable source area (VSA) hydrological processes in the landscape. We developed and tested a distributed approach for applying the traditional SCS-CN equation to watersheds where VSA hydrology is a dominant process. Predicting the location of source areas is important for watershed planning because restricting potentially polluting activities from runoff source areas is fundamental to controlling non-point-source pollution. The method presented here used the traditional SCS-CN approach to predict runoff volume and spatial extent of saturated areas and a topographic index, like that used in TOPMODEL, to distribute runoff source areas through watersheds. The resulting distributed CN,VSA method was applied to two subwatersheds of the Delaware basin in the Catskill Mountains region of New York State and one watershed in south-eastern Australia to produce runoff-probability maps. Observed saturated area locations in the watersheds agreed with the distributed CN,VSA method. Results showed good agreement with those obtained from the previously validated soil moisture routing (SMR) model. When compared with the traditional SCS-CN method, the distributed CN,VSA method predicted a similar total volume of runoff, but vastly different locations of runoff generation. Thus, the distributed CN,VSA approach provides a physically based method that is simple enough to be incorporated into water quality models, and other tools that currently use the traditional SCS,CN method, while still adhering to the principles of VSA hydrology. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Analytical solution to a bias in the TOPMODEL framework balance

HYDROLOGICAL PROCESSES, Issue 7 2004
G.-M. Saulnier
Abstract The increasing need for distributed hydrological modelling leads to an intense use of spatially distributed predictions of physically based models, such as TOPMODEL as addressed here. The ability of these models to reproduce the internal behaviour of catchments physically is increasingly tested through field experiments (geochemical investigation, distributed measurements network, etc.). This paper will show that, in the case of TOPMODEL, an implicit approximation remains in the classic derivation of the equations that consists in neglecting the surface of saturated areas with respect to the total surface of the catchment. This simplifying, though unnecessary, approximation leads to a systematic underestimation of the catchment water storage deficit and to divergence in the water budget accounting. This may also significantly change the predicted ratio between subsurface and surface water fluxes in the total discharge. An analytical solution is suggested that leads to water balance accounting which is better defined, and more consistent in comparison with field water storage recording. It is expected that this work will ensure more accurate TOPMODEL predictions, consistent with the assumptions of the model. This will then improve the interpretation of comparisons between results of simulation and field experiments. Copyright © 2004 John Wiley & Sons, Ltd. [source]

A network-index-based version of TOPMODEL for use with high-resolution digital topographic data

HYDROLOGICAL PROCESSES, Issue 1 2004
S. N. Lane
Abstract This paper describes the preliminary development of a network-index approach to modify and to extend the classic TOPMODEL. Application of the basic Beven and Kirkby form of TOPMODEL to high-resolution (2·0 m) laser altimetric data (based upon the UK Environment Agency's light detection and ranging (LIDAR) system) to a 13·8 km2 catchment in an upland environment identified many saturated areas that remained unconnected from the drainage network even during an extreme flood event. This is shown to be a particular problem with using high-resolution topographic data, especially over large appreciable areas. To deal with the hydrological consequences of disconnected areas, we present a simple network index modification in which saturated areas are only considered to contribute when the topographic index indicates continuous saturation through the length of a flow path to the point where the path becomes a stream. This is combined with an enhanced method for dealing with the problem of pits and hollows, which is shown to become more acute with higher resolution topographic data. The paper concludes by noting the implications of the research as presented for both methodological and substantive research that is currently under way. Copyright © 2004 John Wiley & Sons, Ltd. [source]