Spatial Variability of Soil Erodibility (K Factor) at a Catchment Scale in Nanjing, China

Abstract

We conducted a study to examine the spatial variability and vertical characteristics of soil erodibility (the K factor) and its relationship to vegetation types, based on a case of study on Dengxia catchment, Jiangsu Province, China. Using traditional statistical and geostatistical methods, the K factor was calculated by the EPIC model. The results showed the following: (1) the K value on the studied area was highly spatially variable, with a range from 0.15 to 0.50, a mean of 0.13, and a coefficient of variance of 22.11%; (2) the overall spatial distribution of the K values presented a clear belt shape and was higher in the northwest than in the southeast, with several high K-value centers clustered in the central and southern parts of the region. The results showed that the K factor of the areas covered by forest, mainly in the northern part, was greater than that of farmland and human residential areas in the central and southern part of the region. (3) The vertical (soil depth) variability of the K value by vegetation type followed the order K(0–20 cm) < K (20–40 cm) < K (40–60 cm) overall in the region, while farmland followed a different order, K (0–20 cm) < K (40–60 cm) < K (20–40 cm). It was shown that the K factor in the topsoil (0–20 cm) was the greatest, except for farmland. For K factor of different vegetation types in the topsoil (0–20 cm), the order was as follows: fallow land > tea garden land > farmland > grassland > broadleaf forestland > bamboo shrub land > coniferous forestland > bamboo forestland.