Topografins inverkan på markvattenhalten i ett jordbruksdominerat avrinningsområde

Abstract: Topography is an important parameter for catchment hydrology, since it is a driver for water flow. Moreover, topography serves as a basis for hydrological models, e.g. ‘Top-model’, which is based on a topographical wetness index (TWI). Few studies of TWI have been conducted on agricultural catchment scale. Four fields were studied in a Swedish drained agricultural catchment in order to evaluate the influence of topography on soil wetness. Average slope for the four fields was 4.0-9.4 degrees and the TWI index was found to vary between 2.6 and 14.2 in 820 measuring points. Calculated TWI values were not correlated to the measured water content for each point. However, some of the fields had significantly different TWI values compared with others soon after snowmelt. The complexity of the relationship between TWI, topography and other factors, including the existence of tile drains, is discussed in this report.