Work package 2 quantifies key processes that regulate yield and quality of water exported from the HaeanBasin, focusing on nitrogen, phosphorus and dissolved organic carbon (DOC), which impact drinking water supplies of the LakeSoyang reservoir. The overall rationale for research performed in WP 2 is based on the integrated modelling of water and solute fluxes in small catchments using a numerical code. Parameterization and subsequent calibration of the model will be performed with data obtained for the HaeanBasin. The upper boundary conditions, i.e. meteorological inputs, are provided via WP I.
Field surveys, soil sampling and soil analyses are conducted to define soil functional groups and parameters important to hydrology and erosion modelling. “Learning classifier systems” such as CART, ANN and Fuzzy rule-based approaches will be applied to describe soil distribution for areal landscape modelling.
Erosion during storm flow, transport of materials from agricultural fields, and management influences are assessed in field studies, using an integrated experimental strategy within run-off plots. DOM and fPOM fluxes are measured in the run-off plots at different runoff rates, but also in forest floor percolates and in runoff from forested sub-catchments, examining in particular the extreme events associated with the monsoon. Fluxes of dissolved (DOM) and fine particulate organic matter (fPOM) are also done in small streams and in tributaries within HaeanBasin.
Water flow through soil matrices and macropores are assessed through application of dye tracers.
Isotope studies with 15N(Project 08) permit examination of uptake by plants, movement by percolation to deep soil layers, lateral transport, and overall retention within the farmland ecosystems. Determined pools and fluxes of main elements depending on land use are used for modelling and upscaling of nutrient budgets to the small catchment scale.
Experimentally, charred biomass and synthetic polymers are applied in the run-off plots to determine whether these additives can contribute significantly to sustainable farming methods in the HaeanBasin.
A detailed characterization of river and shallow aquifer exchange is being performed on several reaches of major streams within the HaeanBasin using hydraulic and temperature gradients and flow-measurements. DOC and nitrate concentrations will be measured in shallow piezometers in transects across the river system. Additionally, a network of sites for monitoring of water quality together with flow rates during rain events and for long-term monitoring of ground water quality has been established.
Overall, this work package will establish a modelling framework to perform scenario simulations that allow the study of climate effects and land use changes on water quality and water yield in complex terrain. Thus, the tools developed within the context of TERRECO will allow us to examine potential water quality impacts on the reservoir of LakeSoyang, which is also already the subject of monitoring efforts within the group.