BO-I-2: Rainfall erosivity – case study

The picture shows a field with young plants. A large erosion gully without vegetation runs through the field.Click to enlarge
Increasing precipitation intensities increase the risks of soil loss.
Source: Photograph: © murasal /

2019 Monitoring Report on the German Strategy for Adaptation to Climate Change

Table of Contents


BO-I-2: Rainfall erosivity – case study

High levels of rainfall intensity increase the risks of soil loss. In North Rhine-Westphalia rainfall erosivity in summer has increased significantly since the 1970s. In respect of sites with sensitive soils on major inclines this means that, especially in terms of agricultural use of soils, protection measures against soil erosion have to be taken.

The line graph shows the rainfall intensity in kilojoules per square metre times millimetres per hour. The period from 1970 to 2007 is shown. The values fluctuate strongly between the years and range from less than 20 in 1976 to more than 90 in 2006. The time series has a significantly increasing trend.
BO-I-2: Rainfall erosivity – case study

The line graph shows the rainfall intensity in kilojoules per square metre times millimetres per hour. The period from 1970 to 2007 is shown. The values fluctuate strongly between the years and range from less than 20 in 1976 to more than 90 in 2006. The time series has a significantly increasing trend.

Source: Landesamt für Natur Umwelt und Verbraucherschutz NRW (climate impact monitoring North Rhine-Westphalia)

Loss of soil caused by water and wind impacts – painful losses

Soils are the result of development processes extending over thousands of years. It takes at least one hundred years, subject to adequate plant growth on weathered rock material, before one centimetre of vital humus-rich soil layer develops. Loss of soil owing to overbuilding or soil erosion therefore constitutes serious damage which is never wholly reversible.

Soil erosion caused by water is one of several intensely discussed impacts of climate change on soils. Frequent heavy rainfall events and increases in summer droughts and winter precipitation are some of the causes of major erosion.

Winter precipitation that does not fall as snow and, in farmland soils usually falls on very gappy vegetation cover, can result in substantial loss of soil. This is aggravated by the fact that climate change and associated temperature rise are inclined to shift the development phases of plants including cultivated crop plants. Any resulting changes in ground cover are likely to increase erosion risks. At any rate, drought-related gaps in the vegetation and desiccated soil surfaces are bound to exacerbate erosion. Especially in northern Länder near the coast, wind is an additional cause of erosion on predominantly sandy soils. Increasing spring and summer droughts can only heighten the risks of wind erosion.

Soil erosion primarily signifies reduced efficacy of the soil and a loss of the topsoil rich in nutrients and humus. Eroded soil material is shifted horizontally across the surface and can end up in neighbouring water bodies. This is where diffuse mineral inputs, especially phosphorus, can cause undesirable eutrophication. Such processes are likely to counteract any efforts to enhance the condition of water bodies. Soil erosion is hardly visible; it is an insidious process leading to the impairment of important soil functions. Soil erosion can very quickly cause the loss of soils which have taken several centuries to develop.

Erosion monitoring that would cover the whole of Germany has yet to be invented. So far, soil monitoring conducted in existing permanent monitoring areas (BDF) is the only measuring network covering all of Germany’s Länder for the purpose of long-term data collection on soil erosion nationwide. However, neither the procedures nor the intensity follow a homogeneous approach. Nevertheless, it is possible, despite the lack of representative monitoring data to infer nationwide threat potentials.

The essential factors contributing to the amount of soil erosion caused by water are precipitation, site incline, soil properties, degree of ground cover and the type of soil use. Soil use signifies the type of tillage which, in connection with the direction of tillage is much influenced by the way a field is structured. Nurse crops can be used to increase ground cover in permanent cultivation (e.g. vineyards) but also in annual crops in order to reduce the degree of erosive effects. Types of agricultural crops with particularly high potential for soil loss include potatoes, maize, sugarbeet and winter wheat as well as numerous special crops and vineyards on steep slopes. The specific variable which is likely to have the greatest direct influence on erosion risks – more than any other interactions of climate change and water-related soil erosion – is the amount of change in precipitation intensity. In respect of all the other contributing factors such as ground cover, there are clearly major uncertainties in assessing the impacts of climate change.

In the case of North Rhine-Westphalia it was possible to use temporally highly disaggregated precipitation data to ascertain the development of precipitation-related erosivity. From the mid-1970s onwards the time series shows a significant trend towards increasing rainfall erosivity, thus indicating the risk of increased loss of soil. It has so far not been possible to update the relevant data. The Federal Government and several Länder are currently working on this issue with the objective to be able to provide a much enhanced indicator in the next Monitoring Report.

There is a diverse range of measures conceivable for preventing erosion, in particular in arable fields. The options range from site-adapted crop rotation which ensures continuous ground cover for the entire year, to nurse crops and the use of mulches, to adapting the direction of tillage as well as permanently ploughless, conservation- oriented soil tillage, in order to maintain a natural soil structure and to achieve particularly thorough ground cover by means of protective plant remnants.

The existing data and results demonstrate that climate change has major impacts on soil erosion. For a reliable evaluation of climate-related changes to soil erosion by means of representative measuring data, it is necessary to develop an even closer network with the purpose of carrying out continuous standardised measurements with a strong focus on particularly endangered, climate-vulnerable natural areas. Important technical approaches can be derived from current activities concerned with developing the conception and implementation of an ‘association dedicated to climate change-related soil monitoring’.



BO-I-1: Soil moisture levels in farmland soil

BO-R-2: Permanent grassland



Protection of the ecological efficacy of soils by means of reducing or preventing soil erosion and soil compaction and by maintaining organic matter content (DAS, ch. 3.2.4)

As far as possible avoiding soil losses by ensuring site-adapted use, especially by taking into account slope gradient, water and wind conditions as well as ground cover (BBodSchG, § 17 (2) 4)

Continuous reduction of soil erosion by 2020 (NBS, ch. B 2.5)