F. Schöberl

Quantification of Soil Moisture Effects on Runoff Formation at the Hillslope Scale

AbstractPre-rain-event soil moisture (preSM) plays a crucial role when evaluating runoff formation during heavy rainfall. Using sprinkling experiments and numerical modeling, this study investigates the impact of preSM on runoff formation at the small hillslope scale (≤100  m2). Sprinkling experiments were conducted on three sites in the Austrian Alps and observed hydrological behavior was simulated by using the hillslope model HILLFLOW. For each site, runoff was modeled with different preSM scenarios, covering the whole soil moisture range between permanent wilting point and saturation. Depending on the dominant runoff processes, the results showed impacts of preSM on both the maximum runoff and the total runoff. A predominant threshold was observed near field capacity (35 and 32% by volume). In general, the results clearly showed that the consideration of preSM is a prerequisite to reproduce runoff formation and total runoff amounts accurately. Field capacity turned out to be a good indicator (threshold...

Investigating the impact of initial soil moisture conditions on total infiltration by using an adapted double-ring infiltrometer

ABSTRACT This study presents an adaptation of the double-ring infiltrometer (DRI) device, which allows several infiltration experiments to be conducted at the same location. Hence, it becomes possible to use the DRI method to investigate infiltration behaviour under different initial soil moisture conditions. The main feature is the splitting of the inner ring into two parts. While the lower part remains in the soil throughout the investigation period, the upper part is attached to the lower one just before the infiltration experiment. This method was applied to eight test sites in an Alpine catchment, covering different land-use/cover types. The results demonstrated the applicability of the adapted system and showed correlations between total water infiltration and initial soil moisture conditions on pastures, independent of the underlying soil type. In contrast, no correlation was found at forest sites or wetlands. Thus, the study emphasizes the importance of paying special attention to the impact of initial soil moisture conditions on the infiltration—and consequently the runoff behaviour—at managed areas. Given the differences in the total infiltrated water of between 30 and 1306 mm, consideration of the interplay between initial soil moisture conditions, land-use/cover type, and soil properties in rainfall–runoff models is a prerequisite to predict runoff production accurately. EDITOR Z.W. Kundzewicz; ASSOCIATE EDITOR not assigned

Runoff and bedload transport modelling for flood hazard assessment in small alpine catchments - the PROMABGIS model

Successful risk management of flood related hazards like extreme runoff and intense bedload transport in small alpine catchments is strongly dependent on accurate hazard assessment on a local scale. Some currently available methods used by practitioners are simple and therefore result in rather general evidence. Other methods – mostly scientific modelling approaches – are often too sophisticated to be applied for practical use with an economically justifiable effort. Thus, there is a need for a simple but reliable approach for flood related hazard assessment in small alpine catchments. As a consequence of this the model PROMABGIS (PROcess orientated MAss Balances) originally developed by Jenewein (2002) and Rinderer (2002) in cooperation with practitioners (i.n.n. ingenieurgesellschaft fur naturraum-management GmbH & Co KG) has been further developed at alpS - Centre of Natural Hazard Management for estimating runoff and bedload transport in ungauged catchments of small size and alpine character. The model concept of both, the runoff and bedload transport module, are presented in this paper. Moreover first results of model validation using measurements of flood events in the Erlenbach catchment (Switzerland) give proof of the models potential for estimating runoff and bedload transport in small alpine catchments.

Flood Forecasting for the River Inn

The river Inn as the main river in Tyrol moulds the settlement and economic area in Northern Tyrol in a considerable way. 66 % of the area drains into the Inn, whereas the remaining 34% drain into the Lech, the Grossache and the Drau in East Tyrol. The Inn flows through Tyrol for about 200 km, from the Swiss border at Martinsbruck to Kufstein, where it leaves Tyrol and flows into Bavaria/Germany (Fig. 2.1).

Climate change effects on hydrological system conditions influencing generation of storm runoff in small Alpine catchments

1 Institute of Geography, University of Innsbruck, Innsbruck, Austria 2 Institute of Meteorology, University of Natural Resources and Life Sciences, Vienna, Austria Department of Natural Hazards, Federal Research and Training Centre for Forests, Innsbruck, Austria 4 Institute for Earth and Environmental Sciences, University of Potsdam, Potsdam, Germany Correspondence Gertraud Meißl, Institute of Geography, University of Innsbruck, Innsbruck, Austria. Email: gertraud.meissl@uibk.ac.at