In Greece the hydrological analysis of ephemeral streams has been especially difficult due to the lack of precipitation and discharge gauges. This study focuses on the investigation of possible relationship between mo...In Greece the hydrological analysis of ephemeral streams has been especially difficult due to the lack of precipitation and discharge gauges. This study focuses on the investigation of possible relationship between morphometric characteristics of small to medium drainage basins and hydrological indices in order to discover morphometric parameters “predictors” of flash flood potential of ungauged catchments. Twenty-two morphometric parameters of twenty-seven drainage basins (ranging in area between 3.6 km2 and 330.5 km2) located in the northern part of the Peloponnese in southern Greece were calculated utilizing GIS software ArcGIS10. Hydrological modeling was performed using a simplified Matlab implementation of TOPMODEL, a conceptual model based on the principle of variable contributing area to runoff production through saturated overland flow, and LISEM, a physically based hydrologic and soil erosion model. Rainfall-runoff simulations were performed for an extreme precipitation event. The simulations outcomes, which include the peak discharge, time to peak and the percentage runoff, were correlated with the morphometric parameters of the catchments. Results were not consistent between the two models, probably due to their different structure, with the LISEM results being closer to what is anticipated. The results demonstrate that area, length of the basin, perimeter and compactness factor appear better correlated with the peak discharge (Qpeak) of the catchment. The same parameters as well as Melton’s number correlate with percentage runoff (C), while “celerity” of the flood wave (length of the basin/time to peak) is better correlated with relief, indicating that as the relief becomes greater, the response of the basin becomes fastest.展开更多
The movement of vehicles on the roads, during summer, can sometimes hide risks involved in direct sunlight. In places where the relief is complicated, road network usually consists of a road complexity. This complexit...The movement of vehicles on the roads, during summer, can sometimes hide risks involved in direct sunlight. In places where the relief is complicated, road network usually consists of a road complexity. This complexity in conjunction with the motion of a vehicle on a road and the position of the sun at the same time may result in the loss of vision in some sections of the road. This paper describes a GIS-based methodology of the spatiotemporal analysis of this phenomenon. Thus, for a given study area, in this case ofMilos Island,Greece, the geometry of the road network, the terrain morphology and the solar radiation (in specific time intervals during summer) have been analyzed. The result of this procedure is a map illustrating the sections of the road where direct sunlight includes a serious amount of risk for the drivers. Applying this methodology for long periods of time may lead to prevention policies adoption related to accidents of direct exposure to sunlight. Moreover, this methodology could be an additional module in car navigation systems.展开更多
文摘In Greece the hydrological analysis of ephemeral streams has been especially difficult due to the lack of precipitation and discharge gauges. This study focuses on the investigation of possible relationship between morphometric characteristics of small to medium drainage basins and hydrological indices in order to discover morphometric parameters “predictors” of flash flood potential of ungauged catchments. Twenty-two morphometric parameters of twenty-seven drainage basins (ranging in area between 3.6 km2 and 330.5 km2) located in the northern part of the Peloponnese in southern Greece were calculated utilizing GIS software ArcGIS10. Hydrological modeling was performed using a simplified Matlab implementation of TOPMODEL, a conceptual model based on the principle of variable contributing area to runoff production through saturated overland flow, and LISEM, a physically based hydrologic and soil erosion model. Rainfall-runoff simulations were performed for an extreme precipitation event. The simulations outcomes, which include the peak discharge, time to peak and the percentage runoff, were correlated with the morphometric parameters of the catchments. Results were not consistent between the two models, probably due to their different structure, with the LISEM results being closer to what is anticipated. The results demonstrate that area, length of the basin, perimeter and compactness factor appear better correlated with the peak discharge (Qpeak) of the catchment. The same parameters as well as Melton’s number correlate with percentage runoff (C), while “celerity” of the flood wave (length of the basin/time to peak) is better correlated with relief, indicating that as the relief becomes greater, the response of the basin becomes fastest.
文摘The movement of vehicles on the roads, during summer, can sometimes hide risks involved in direct sunlight. In places where the relief is complicated, road network usually consists of a road complexity. This complexity in conjunction with the motion of a vehicle on a road and the position of the sun at the same time may result in the loss of vision in some sections of the road. This paper describes a GIS-based methodology of the spatiotemporal analysis of this phenomenon. Thus, for a given study area, in this case ofMilos Island,Greece, the geometry of the road network, the terrain morphology and the solar radiation (in specific time intervals during summer) have been analyzed. The result of this procedure is a map illustrating the sections of the road where direct sunlight includes a serious amount of risk for the drivers. Applying this methodology for long periods of time may lead to prevention policies adoption related to accidents of direct exposure to sunlight. Moreover, this methodology could be an additional module in car navigation systems.
