Developing a new grey dynamic modeling system for evaluation of biology and pollution indicators of the marine environment in coastal areas

Pollution of the marine environment leads to corresponding changes within the ecosystem. Thus, evaluation of the marine environment for management purposes, which is a procedure complicated by multi-hierarchy, multi-factors, and multi-uncertainty, should be considered from both ecological and environmental standpoints. Currently, the lack of consideration of the relationship between bio-indicators and water pollution in marine environmental evaluation hinders the efforts of conventional modeling approaches in this field. This paper presents an innovative dynamic modeling system that we call the grey dynamic modeling system (GDMS). This system synthesizes the analytic hierarchy process (AHP), grey target theory (GTT), and grey forecasting modeling approaches (GM(1,1)), and it takes both ecological and environmental factors into account during evaluation and forecasting of the marine environment in coastal areas. To effectively eliminate the subjective errors of the traditional AHP process, the GTT analysis is used to replace expert scoring, which defines the grey relational grades of the bio-indicator indices(BI) and the water pollution indices(WPI).The structure of the AHP then is applied to link the bio-indicators and pollution, which enables the system to generate the primary factors necessary for the evaluation of the marine environment from both ecological and pollution perspectives. The new modeling system was used to evaluate and forecast the marine eco-environment in the Tianjin section of Bohai Bay, China. This case study highlights the key features of the approach. The bio-indicator indices(BI) and water pollution indices(WPI) monitoring data from 2002 to 2007 of 8 monitoring sites are input to this dynamic modeling system and the results illustrate the following: Pollution of the study area is currently serious and tends to be worse in the future, and the worst areas are sites 2, 3, and 4 based on their key pollution indices biochemical oxygen demand (BOD), dissolved inorganic phosphorus (DIP), and dissolved inorganic nitrogen (DIN)) which have the main effects on marine eco-system. These results can be used as the basis for marine environmental manager to define the key pollution factors, key pollution sites and the pollution trends of the marine environment of the whole study area.