Development of new drainage factor in ECOSSE model to improve water dynamics and prediction of CO2 fluxes from drained peatlands
Authors: Premrov Alina , Wilson David , Saunders Matthew , Yeluripati Jagadeesh , Renou-Wilson Florence 
Published: March 2021

&lt;p&gt;ABSTRACT&lt;/p&gt;&lt;p&gt;Drained peatlands often act as carbon source and their drainage characteristics can be challenging to accommodate in biogeochemical models. This study uses the ECOSSE process-based&amp;#160; biogeochemical model [to simulate water-table level and CO&lt;sub&gt;2&lt;/sub&gt; fluxes (heterotrophic respiration) &lt;sub&gt;[1]&lt;/sub&gt;], and empirical data from two Irish drained peatlands: Blackwater and Moyarwood, which were partly rewetted (both sites are extensively described in earlier studies &lt;sub&gt;[2]&lt;/sub&gt;). Here we explain details on the development of a new drainage factor with seasonal variability Dfa(i) for drained peatlands, based on our recently published work &lt;sub&gt;[3] &lt;/sub&gt;&amp;#160;that we hope can contribute towards the potential future development of IPCC Tier 3 emissions reporting. The Dfa(i) was developed using empirical data from Blackwater drained bare-peat site (BWdr) and its application was further tested at the Moyarwood site under drained (MOdr) and rewetted conditions (MOrw) &lt;sub&gt;[3]&lt;/sub&gt;. The development of the Dfa(i) was carried out in three main steps &lt;sub&gt;[3]&lt;/sub&gt;: 1 - identification of the &amp;#8216;wt-discrepancy event&amp;#8217;; 2 - development of Dfa without seasonal variability, and 3 - accounting for seasonal variability and development of Dfa(i). Dfa(i) was then applied to the rainfall inputs for the periods of active drainage in conjunction with the measured water-table inputs &lt;sub&gt;[3]&lt;/sub&gt;. As explained in our published work &lt;sub&gt;[3]&lt;/sub&gt;, the results indicate that the application of Dfa(i) could improve the model performance to predict water-table level (BWdr: r&lt;sup&gt;2 &lt;/sup&gt;= 0.89 MOdr: r&lt;sup&gt;2 &lt;/sup&gt;= &amp;#160;0.94); and CO&lt;sub&gt;2&lt;/sub&gt; fluxes [BWdr: r&lt;sup&gt;2&lt;/sup&gt; = 0.66 and MOdr: r&lt;sup&gt;2 &lt;/sup&gt;= 0.78) under drained conditions, along with ability of the model to capture seasonal trends &lt;sub&gt;[2]&lt;/sub&gt;. The model simulation of CO&lt;sub&gt;2&lt;/sub&gt; fluxes at MOrw site was also satisfactory (r&lt;sup&gt;2&lt;/sup&gt;=0.75); however, the MOrw water-table simulation results suggest that additional work on the water model component under rewetted conditions is still needed &lt;sub&gt;[3]&lt;/sub&gt;. We further discuss our insights into potential opportunities for future additional improvements and upgrading of the ECOSSE model water module.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;&amp;#160;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgements&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;The authors are grateful to the Irish Environmental Protection Agency (EPA) for funding the AUGER: Project (2015-CCRP-MS.30) under EPA Research Programme 2014&amp;#8211;2020. Full acknowledgements are provided in Premrov et. al (2020) &lt;sub&gt;[3]&lt;/sub&gt;.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Literature&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;[1] Smith, J., et al. 2010. ECOSSE. User Manual.&lt;/p&gt;&lt;p&gt;[2] Renou-Wilson, F., et. al. 2019. Rewetting degraded peatlands for climate and biodiversity benefits: Results from two raised bogs. Ecol. Eng. 127:547-560.&lt;/p&gt;&lt;p&gt;[3] Premrov, A., D. Wilson, M. Saunders, J. Yeluripati and F. Renou-Wilson (2020). CO&lt;sub&gt;2 &lt;/sub&gt;fluxes from drained and rewetted peatlands using a new ECOSSE model water table simulation approach. Sci. Total Environ. (https://doi.org/10.1016/j.scitotenv.2020.142433; on-line 2020; in print Vol. 754, 2021; under CC BY 4.0).&lt;/p&gt;