Threshold Of Landscape And Water Quality In Rapidly Urbanizing Coastal Areas Of Lianyungang City

In China, concern is growing with regard to environmental issues related to the growth of urban zones. Coupled human and natural systems are integrated systems in which people interact with natural components. With the increasing disturbance of human, the human impacts have made significant changes to ecosystem. It is evident in recent years that urbanization has been one of the leading anthropogenic activities causing the destruction of natural ecosystems in China due to its thriving economy. Especially, the coastal cities are experiencing rapid urbanization, which has resulted in many challenges. Therefore, this paper performed a study in a human dominated area of eastern coastal city of China, Lianyungang, and a seaport city in Jiangsu Province.This paper presented a comprehensive index system for assessment of the level of urbanization based on four aspects:demographic urbanization, economic urbanization, social urbanization and spatial urbanization. The developed index system also characterizes the environment based on three factors:environmental pressure, environmental level and environmental control. Furthermore, a coupling coordination degree model (CCDM) focusing on the degree of coordination between urbanization and the environment was established using panel data collected from2000to2008for Lianyungang. The results showed that both sub-systems evolved into a superior balance during rapid urbanization, and the social urbanization and environmental control make the greatest contribution to the coupling system, indicating that they are the critical factors to consider when adjusting coordination development during decision-making.Within the context of Lianyungang’s peri-urban development and findings of the CCDM, the study area was divided into three spatial layers:center, inner peri-urban and outer peri-urban. Changes of landscape pattern from2000,2004and2008in Lianyungang were analyzed by FRAGSTATS with seven metrics in these three zones. It analyzed the relationship between urban land use pattern and water quality over space and time, which showed that the land uses pattern metrics in center area were closely correlated with water quality variables at the0.01p level, like CODMn, NH3-N, P and As. And the number of land use pattern metrics and water quality variables that had significant relation in2008are much more than2000and2004, which to some extent due to the significant change between2004and2008. For the class level, the PD, LPI, and ED appear to be important factors in the relationship between water quality and land uses.With the increasing disturbance of human, the human impacts have made significant changes to ecosystem. The analysis of thresholds is complicated by nonlinear dynamics and by multiple factor controls that operate at diverse spatial and temporal scales. Therefore, within the context of Lianyungang’s peri-urban development, the results would reveal the effects and impacts of urban development on the peri-urban regions, including spatial and temporal change of land cover in different scales. It have found that the non-linear between ED and COHESION and CODMn, BOD, NH3-N and P, the order of R2are CODMn>P>BOD>NH3-N>Oils>DO, which is due to the NPS pollution from agricultural and aquacultural runoffs of fertilizers, pesticides and manure. The’safe values’of landscape metrics before the change of each turning or standard threshold can be determined and guidelines for sustainable management activated at a level before thresholds are reached.