Project Fuzzy rule based nitrate transport modelling
Headed By Dr. Michael Rode (Department Aquatic Ecosystem and Management), Prof. András Bárdossy (University of Stuttgart)
Personnel Dr. Rajesh Raj Shrestha
Time Period 2005-2008

Brief description

The transport of nitrate from catchment to river channel is driven by complex bio-chemical and hydrological processes related to nitrogen and water cycles. At the catchment scale, these complex processes may be characterised by different relationships such as between ground water table and river nitrate concentration (flushing hypothesis). Such relationships provide a basis for modelling the catchment scale processes in terms of conceptual relationship between the causative and resultant variables. The fuzzy set theory based methods provide a means of generalising such processes and abstracting knowledge based on the relationships between the datasets. A fuzzy rule based model (FRBM) can describe the relationship between the causative and resultant variables in terms of a collection of “IF-THEN” fuzzy rules. The FRBM also provide a fast, transparent and parameter parsimonious method and allows an explicit consideration of expert knowledge.

The main aim of this research is develop a FRBM nitrate transport model based on the relationship between the input and output variables. The ground water and surface water flow components generated by the TOPMODEL version of the WaSiM modelling system together with average temperature are used as driving variables for modelling the nitrate concentration in the river using the FRBM. The fuzzy rules are assessed from a combination of expert knowledge and input - output data using an optimisation algorithm. The study is undertaken using a high resolution nitrate concentration data from the Weida stream, which is a small tributary to the Weisse Elster river in the Elbe basin. The study further aims at transferring the fuzzy rules to a similar catchment for the simulation of catchment scale nitrate transport processes.