Geographia Polonica (2007) vol. 80, iss. 2

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Extreme Rainfalls and their Impact on Slopes—Evaluation Based on Soil Erosion Measurements (As Exemplified by the Suwałki Lakeland, Poland)

Ewa Smolska

Geographia Polonica (2007) vol. 80, iss. 2, pp. 151-164


Monitoring of soil erosion on selected slopes of the Suwałki Lakeland (NE Poland)was conducted in the years 1987–1989 and 1998–1999. The extreme rainfall was characterisedby an efficiency of 35.7 mm and an average intensity of 0.5 mm per minute. This rainfall causederosion along the entire length of the slopes, and its volume was equal to the average annualvalue. Almost 75% of the material deposited in the lower, concave section of the slopes duringthe 5-year period of measurements was transferred beyond the slope base. Some of the slopesof length over 100 m was cut by networks of rills up to 50 cm deep, and the rate of soil loss was30 t ha-1. This rainstorm was most important in respect to the intensity and transfer of eroded soilmaterial, and was a decisive factor in soil loss and in the redistribution of soils on the slopes overthe entire period of measurement.

Keywords: rainfall, extreme events, soil loss, soil erosion and deposition, NE Poland