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There is no doubt that extreme floods are firstly the result of heavy and widespread rainfall events. On the other hand, there are some impacts on floods due to human actions. For instance the process of urbanising consisting of “sealing the landscape” by buildings and traffic areas and the process of developing sewer systems to discharge stormwater runoff by the principle “as fast and effective as possible” changes the water balance of the catchment significantly. The effects on floods can be twofold: increased flood volume caused by an increase in surface runoff and increased peak values by reducing the duration of runoff. Another example of human impacts on floods is increased runoff from agricultural areas, especially arable lands. Because of the increasing weights of farming machines, the soil becomes compressed and the infiltration capacity decreases. The effects of human actions on floods may differ from event to event with the tendency, “the higher the flood the lower the human impacts”, because of the growing runoff from natural parts of the catchments in cases of extreme floods. But, there is no doubt that human activities mentioned before have led to a certain intensification of all floods. So it is logical to ask if there are possibilities to replace these activities partly by alternatives with less impacts on floods and without significant disadvantages. This paper aims to investigate such alternatives related to urban drainage systems and arable lands. |
