The loss of agricultural areas can be identified by using the statistical office’s land survey information on purposes of land use. This survey was conducted every 4 years before 2008 and annually from 2009 onwards. The remaining values have been linearly interpolated.
For the monetary valuation of land conversion the average market price per hectare of agricultural area in the respective year is used, which is published by the Federal Statistical Office (Stat. Bundesamt, Fachserie 3, Reihe 2.4 „Land- und Forstwirtschaft, Fischerei: Kaufwerte für landwirtschaftliche Grundstücke 2013“, Tab. 1.6 Verkäufe im Zeitvergleich, Stand 22.8.2014).
Two options are discussed, described in detail in the methodology of component 19: An annual account of damage costs and a cumulative approach, adding all damages since 1910 according to the “savings principle”. For reasons explained in component 19 we take the former approach.
The annual loss or gain of agricultural areas (in hectares) is thus multiplied by the average price of one hectare of agricultural land in the respective year. The price adjusted values then add negatively – in case of area loss – or positively – in case of extension of agricultural land – to the NWI.