Thickness of oxidizable peat
Description
The peat thickness map was commissioned by the province of Zuid-Holland by Alterra Wageningen UR (2016). The aim was to gain insight into the areas where oxidation of peat by dewatering will occur. Since the drainage of the peatlands, there has been a drop in ground level, and as long as this situation persists, the ground level continues to fall until the peat, insofar as it comes into contact with oxygen, is exhausted. Presented are the locations and thicknesses of oxidizable peat with steps of 0.5 meters to as deep as there is peat. How much peat can oxidize in the long term depends on a number of factors such as drainage, precipitation / temperature (climate change) and land use. Without further action, climate change will increase ground level decline due to higher temperatures and deeper groundwater levels in the summer. How long there is still peat and which ground level height / depth is reached in the long run obviously also depends on the actual peat thickness. That thickness can be derived from the Soil Map, along with deep profile descriptions. Because there are relatively few deep profile descriptions, a grid file is composed of the geological profiles. The peat thickness is defined here as the thickness that can oxidize during agricultural dewatering. A mineral substrate or intermediate layer of >40 cm is considered to be the underside of the oxidizable peat layer. Peat can still occur under the mineral layer, but that will remain anaerobic and will not oxidize. To determine the peat thickness from the Soil Map, an updated map has been used in which recent revisions have been incorporated. As a result, the card is based on a wide range of shooting dates: From 1961 to 2014. To determine the peat thickness, the profiles for the soil units set up by de Vries (1999) were used as much as possible. These profiles are based on the original profile descriptions. For profiles that are missing, the ‘average’ layer thicknesses have been used according to the legend in the Soil Map. Soil surfaces where a mineral substrate has been found within 120 cm, e.g. Vk, are assumed to be so thick that any peat under that layer will never oxidise. There (and for all mineral soils) the geological profiles have not been taken into account. Because the recording dates of the Soil Map differ for more than half a century, decimeters of difference in ground level descent may have occurred. In order to estimate the current peat thickness, this decrease was calculated and subtracted from the peat thickness map. For the calculation, the method described in Jansen (2009) was used.
Resources
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https://geoservices.zuid-holland.nl/arcgis/services/Bodem/Bodem_bodemdaling/MapServer/WMSServer?request=GetCapabilities&service=WMS |