Over the past few decades, a number of studies have dealt with the impact of antecedent soil moisture conditions (ASMC) on infiltration and, consequently, on runoff behaviour (IRB). At the hillslope scale (100 m) and below, these studies are generally based on field methods like sprinkling or infiltrometer experiments. However, the applicability of these methods to investigate the ASMCIRB correlation is limited. Owing to their impact on soil structures, site characteristics get disturbed or even destroyed after the first run, thus influencing infiltration behaviour.
In order to better understand the complex relationship between the ASMC and IRB, several runs at different ASMC at the same site would be necessary. For that, two approaches were developed in this thesis and tested at different land-use/cover types in Alpine catchments. While the first is an improvement on the popular double-ring infiltrometer device, the second is a combination of sprinkling experiments and hydraulic-hydrological modelling. The application of these two methods enables to quantify the impact of ASMC on the IRB across the entire soil moisture range. Additionally, both approaches have a low impact on the physical properties of the sites, enabling repeated tests without affecting the initial conditions.
Moreover, as climate change is expected to have a significant impact on the ASMCand consequently on the IRBit is important to assess possible changes in advance. Thus, in the final step, the impact of ASMC on the IRB is quantified in the light of climate change. For that, prospective changes in Alpine soil moisture regimes and, consequently, in runoff formations are simulated for two climatically different Alpine regions (wet regions versus inner Alpine dry valleys).
Overall, results show an impact of the ASMC on the IRB. It, however, depends on different factors such as the dominant runoff processes and the land-use/cover pattern. Further, by combining sprinkling experiments and hydraulic-hydrological modelling, it was possible to show that compared to the total amount of runoff the maximal runoff rate remained unchanged under altered ASMC. This approach also enabled the identification of a soil moisture threshold on the hillslope scale at about field capacity.
Regarding prospective Alpine soil moisture regimes, simulated scenarios showed a remarkable decrease in soil moisture during the summer months. However, different behaviours were observed at the two different regions. Compared to the relatively dry region, the soil moisture decrease in the relatively wet region was far more pronounced. This was primarily attributed to the water-releasing strategy of the vegetation, leading to reduced soil moisture content and, consequently, to reduced runoff formation.