Examination of the erosion on the Lyukas kurgan with the USLE model

Abstract

The amount of soil erosion was not signed on the Great Hungarian Plain on the maps of the 1970s because the relief did not suggest it. Our knowledge and tools in informatics today gives opportunity to outline areas with erosion models (USLE, RUSLE, WEPP, EUROSEM, MEDRUSH etc.) where smaller erosion rate occurs. Kurgans are hundreds of years old. During their research an important question is important to answer: “How fast can a more than a thousand year old artificial mound erode?” Our research site was the Lyukas Kurgan in the present investigation. We calculated the soil loss with the USLE model (A= R K L S C P), assuming natural vegetation and no human disturbance. Input parameters are as follows: R = 140 (MJ mm ha-1 h-1 y-1), K = 0,018 (t ha h ha-1 MJ-1 mm-1), L,S = 3 D model, C = 7 values as scenarios (0,025-0,175), P = 1. Based on the results of the modeling, it can be stated that soil loss reached its maximum in a 10-15m distance from the top of the kurgan. Maximum soil loss values with the different input C values were 0.2–2 t ha-1 y-1. With an average assumed bulk density (1.5 g cm3) of the topsoil of the kurgan, the thickness of the soil loss can be calculated. With the maximum value of 2 t ha-1 y-1 and calculating for 1000 year period, the soil loss was 0.13m. It is obvious that these values are very low, and input parameters are not taking into account the intensive use of the kurgan that caused less dense vegetation and higher compaction (thus higher amount of runoff). These factors highly increase the amount of soil loss, so the final values can be significantly higher.