Abstract. Soil subsidence is one of the major issues in the
management area of the water authority Amstel, Gooi and Vecht, including
emissions of greenhouse gases. This paper describes four different methods
to calculate these emissions in agricultural peat meadows, based on (1) the
mean lowest groundwater level, (2) the mean groundwater level, (3) the
subsidence rates and (4) general numbers. The emissions were calculated in
two polders (about 2600 ha peat meadow), these were comparable for all
methods, ranging from 42 up to 50 kton CO2-eq yr−1 (based on data of
2015), which is about 14.5 up to 19 t CO2-eq ha−1 yr−1. Besides, the
greenhouse gas emissions were compared for different policy scenario's in
one polder subunit (283 ha): (1) standard policy (lowering surface water
level at the same rate as soil subsidence taking place), (2) passive
rewetting (surface water level fixation), (3) subsurface irrigation by
submerged drains, and (4) a maximum surface water level decrease of 6 mm yr−1.
Comparing the four policy scenario's in one polder subunit, greenhouse gas
emissions were lowest in case of subsurface irrigation, decreasing
greenhouse gas emissions by about 35 %–50 % in this polder compared to
standard policy, meaning a decrease of about 5.5–9.3 t CO2-eq ha−1 yr−1.
This represents a value of about 550–930 EUR ha−1 yr−1 (at a price of EUR 100 per ton CO2-eq). The scenario passive rewetting leads to a decrease of about
12 %–21 %, or 2–3 t CO2-eq ha−1 yr−1 compared to standard policy. The
estimation of the decrease in GHG emissions depends on the assumptions made.
In this study it was assumed that subsurface irrigation halves soil
subsidence. The water board will use the described procedures to estimate
greenhouse gas emissions in the future to support water level management in
areas with peat soils.
Characterizing Redox Potential Effects on Greenhouse Gas Emissions Induced by Water-Level Changes
