Research of coupling of eco-economic systems of soil erosion regions based on the PSR model- A case study of Zhuxi River Basin

The coupling of eco-economic system is a systematic project in region with soil erosion. The system coupling, harmony, rebalancing and self-evolution can be achieved by reducing system pressure, improving system state and enhancing positive human response. Using data from the fields of social economy and physical geography for 2000 and 2009, the Pressure-State-Response model and the entropy weighted indicator system of coupling evaluation were established to analyze eco-economic evolution conditions, primary driving factors and evolution phases of eco-economic system in Zhuxi River Basin (ZRB). The results revealed that: (1) The eco-economic system of ZRB was represented by slight fall in pressure and coupling, significant improvement in state and aggrandizement of human response. The observed average scores in 2000 and 2009 were 80.0 and 79.0 for pressure, 92.7 and 83.8 for coupling, 70.9 and 94.0 for state, 67.5 and 87.5 for response and 66.1 and 93.6 for integrated development, respectively. Also obvious spatial differences were noted among villages, which were characterized by increasing coefficients of variations of 0.08 and 0.21 for pressure, 0.07 and 0.11 for response and 0.09 and 0.19 for coupling in 2000 and 2009, respectively. Decreasing coefficients of variation among villages of 0.09 to 0.06, and 0.07 to 0.05 were noted respectively for state and integrated development. There degree of disequilibrium existed between the level of integrated development and degree of coupling in the region. This suggested an uneven development in ZRB during 2000-2009. The system therefore was not at the self-evolution phase and human intervention needed improvement. (2) The evolution processes of the eco-economic system were controlled by factors such as non-agricultural income, crop farming proportion, arable land area, population migration, net income, investment in soil conservation. These factors constituted the focal point of systematic regulation and control. (3) The eco-economic system of ZRB was either in the late transition phase from "rehabilitating system" to "coupling system", or in transition from highly unstable phase to highly stable phase.