The Effects of Physical Factors on the Storm Hydrograph
The Effects of Physical Factors on the Storm Hydrograph
The Storm Hydrograph refers to graphs that show how a drainage basin responds to a period of rainfall. Storm hydrographs are very important in predicting the flood risk and in making the necessary precautions to avoid damage to property and loss of life. Physical factors are the biotic factors which affect organisms and their surroundings, their surroundings in this case being the drainage basin and therefore the storm hydrograph is affected. These physical factors would be factors such as Basin, Size Shape and Relief, types of precipitation, land use; they contribute to regulating the ways in which a river responds to precipitation.
The size, shape and relief of the basin are very important controls. For instance if the basin is small it is most likely expected that the rainfall will reach the main channel more rapidly than in a larger basin where the rainfall has more area to cover and further to travel therefore reaching the main channel at a slower rate. Therefore lag time would be shorter in a small basin than that of a large basin.
Shape also contributes to the varying lag times of basins. Drainage basins with a circular shape or profile are more likely to have a shorter lag time and a higher peak flow. This is because all the points on the watershed are equally distant from the gauging station. Whereas drainage basin with a more elongated shape or profile tends to have a longer lag time than the circular shape basin because of the extremities of the basin to reach the gauging station. Relief on the other hand refers to the general unevenness of the basin or the elevation or difference in elevation of the landscape. Where gradients are steep with a lot of sloping uneven land such as a valley, water runs-off faster and reaches the river channel more quickly than that of a gentler more even landscape where water will slowly crawl off in to the river channel such as plains.
The Storm Hydrograph refers to graphs that show how a drainage basin responds to a period of rainfall. Storm hydrographs are very important in predicting the flood risk and in making the necessary precautions to avoid damage to property and loss of life. Physical factors are the biotic factors which affect organisms and their surroundings, their surroundings in this case being the drainage basin and therefore the storm hydrograph is affected. These physical factors would be factors such as Basin, Size Shape and Relief, types of precipitation, land use; they contribute to regulating the ways in which a river responds to precipitation.
The size, shape and relief of the basin are very important controls. For instance if the basin is small it is most likely expected that the rainfall will reach the main channel more rapidly than in a larger basin where the rainfall has more area to cover and further to travel therefore reaching the main channel at a slower rate. Therefore lag time would be shorter in a small basin than that of a large basin.
Shape also contributes to the varying lag times of basins. Drainage basins with a circular shape or profile are more likely to have a shorter lag time and a higher peak flow. This is because all the points on the watershed are equally distant from the gauging station. Whereas drainage basin with a more elongated shape or profile tends to have a longer lag time than the circular shape basin because of the extremities of the basin to reach the gauging station. Relief on the other hand refers to the general unevenness of the basin or the elevation or difference in elevation of the landscape. Where gradients are steep with a lot of sloping uneven land such as a valley, water runs-off faster and reaches the river channel more quickly than that of a gentler more even landscape where water will slowly crawl off in to the river channel such as plains.