Land use and water management effects on soil N2O emissions in the Hai He river basin, China

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The project aims at the quantification of impacts of on-going and projected changes in land use (LU), management and environmental conditions on the dynamic exchange of carbon and nitrogen (C & N) components between the terrestrial ecosystem, atmosphere and hydrosphere. Model development will be based on the quantification of spatial variability of N2O (as well as CH4 and CO2) fluxes at field scale obtained from eddy covariance (EC) quantum cascade laser (QCL) and static chamber measurements. Assessment of impacts of LU and management on exchange processes will be obtained by analyzing long-term retrospective as well as prognostic model runs for past, present and future conditions. For quantification of greenhouse gas (GHG) emissions and N-leaching on landscape scale, impacts of regional hydrology processes (e.g. water table dynamics and nutrient dispersion by/ with irrigation) on the biogeochemical cycling of C & N have to be accounted for. To address this complexity, we will couple Mobile2D (the regional version of MOBILE-DNDC) with a regional hydrological model. Mobile2D as well as the coupled system will be used to assess the impact of changes in predicted LU/ management and climate conditions on C & N stocks, the net GHG exchange (NGE), water availability and quality (N-leaching). Simulations driven by a GIS database holding information on LU, soil & vegetation properties and climate will create GHG inventories and sources strengths assessments on field and regional (Hal He basin) scales for a series of actual and potential cropping systems under different development pathways, management practices and climate change scenarios.