Separating surface runoff from tile drainage flow in agricultural lowland catchments based on diatoms to improve modeled runoff components and phosphorous transport
Final Report Abstract
The diatom community and water samples from different sampling places of the study area have been collected during a 2-year period resulting in a total of 1405 diatom and 1516 water samples. Our findings highlight the suitability of diatoms as tracers for hydrograph separation. For example, diatom species composition differed considerably between the tile drainages and river sites and many species showed pronounced affinities with one water body type. Furthermore, diatom community information, such as proportions of species in different moistureand size classes, shows clear differences among the different components (i.e., surface runoff, tile drainage and baseflow/ upstream effect (BF/UE)). End member mixing analysis (EMMA) has been successfully implemented based on geochemical tracers (i.e., Na, Ca, Mg and SO4) and results showed that BF/UE (49%) and tile drainage (38%) were the most important runoff generating processes in our catchment, while tile drainage flow produced the biggest proportion (59%) of total runoff in a wet catchment state. Unfortunately, attempts to include diatom derived indices directly as tracers in the EMMA were ultimately unsuccessful. Potential reasons are: 1) the high temporal dynamics, 2) much lower diatom density and biomass in tile drainage flow than in BF/UE and stream flow, 3) diatom community information, such as proportions of species in different moisture- and size classes, which showed clear differences between the end members, was not suited as tracer in EMMA. However, use of proportional or compositional data in mixing analyses has been the topic of research in different fields. Data transformation techniques and advanced modelling concepts should be integrated in our EMMA framework, enabling the use of this valuable information in hydrological mixing models. To determine the entry pathway of phosphorus, the total P loads of different end members (i.e., surface runoff, tile drainage flow and BF/UE) were determined according to the EMMA outputs and corresponding total P concentrations. Although P-loadings are generally overestimated due to some uncertainties, results show that surface runoff was the major source of phosphorus in our catchment. The second most important P source was BF/UE, while tile drainage played only a minor role in all catchment conditions.
Publications
- 2014. A new method for separating tile drainage flow in a low land catchment using EMMA. 23rd International Diatom Symposium. Sep. 7-12, 2014, Nanjing China
Claas Faber, Naicheng Wu, Uta Ulrich, Nicola Fohrer
- 2014. A new method for separating tile drainage flow in a low land catchment using EMMA. European Geosciences Union (EGU). April 27 – May 02, 2014, Vienna, Austria. Vol. 16, EGU2014-6644
Claas Faber, Naicheng Wu, Uta Ulrich, Britta Schmalz and Nicola Fohrer
- 2014. Diatoms as an indicator for tile drainage flow in a German lowland catchment. European Geosciences Union (EGU). April 27 – May 02, 2014, Vienna, Austria. Vol. 16, EGU2014-4955-2
Naicheng Wu, Claas Faber, Uta Ulrich, Britta Schmalz, Nicola Fohrer
- 2014. Diatoms as an indicator for tile drainage flow in a German lowland catchment. Joint Aquatic Sciences Meeting (JASM). May 18- 23, 2014, Portland Oregon, USA
Naicheng Wu, Claas Faber, Uta Ulrich, Nicola Fohrer
- 2014. Modeling daily chlorophyll a dynamics in a German lowland river using artificial neural networks and multiple linear regression approaches. Limnology15: 47-56
Naicheng Wu, Jiacong Huang, Britta Schmalz and Nicola Fohrer
(See online at https://doi.org/10.1007/s10201-013-0412-1) - 2014. Study progress in riverine phytoplankton and its use as bio-indicator – a review. Austin Journal of Hydrology1: 9
Naicheng Wu, Britta Schmalz and Nicola Fohrer
- 2014. Using diatoms for separation of tile drainage flow in a German lowland catchment. 23rd International Diatom Symposium. Sep. 7- 12, 2014, Nanjing China
Naicheng Wu, Claas Faber, Uta Ulrich, Nicola Fohrer
- 2015. Combination of geochemical and hydrobiological tracers for the analysis of runoff generating processes in a lowland catchment. European Geosciences Union (EGU). April 12–17, 2015, Vienna, Austria. Vol. 17, EGU2015-11513
Claas Faber, Naicheng Wu, Uta Ulrich, Nicola Fohrer
- 2015. Responses of diatom communities to hydrological processes during rainfall events. European Geosciences Union (EGU). April 12– 17, 2015, Vienna, Austria. Vol. 17, EGU2015-5702
Naicheng Wu, Claas Faber, Uta Ulrich, Nicola Fohrer
