Abstract
Urbanization is proceeding rapidly in several developing countries such as China. This accelerating urbanization alters the existing land use types in a way that results in more Non-Point Source (NPS) pollution to local surface waters. Reasonable land use planning is necessary. This paper compares seven planning scenarios of a case study area, namely Wulijie, China, from the perspective of NPS pollution. A System Dynamics (SD) model was built for the comparison to adequately capture the planning complexity. These planning scenarios, which were developed by combining different land use intensities (LUIs) and construction speeds (CSs), were then simulated. The results show that compared to scenario S1 (business as usual) all other scenarios will introduce more NPS pollution (with an incremental rate of 22%-70%) to Wulijie. Scenario S6 was selected as the best because it induced relatively less NPS pollution while simultaneously maintaining a considerable development rate. Although LUIs represent a more critical factor compared to CSs, we conclude that both LUIs and CSs need to be taken into account to make the planning more environmentally friendly. Considering the power of SD in decision support, it is recommended that land use planning should take into consideration findings acquired from SD simulations.
Highlights
Urbanization is proceeding rapidly in several developing countries such as China [1,2]
For other land for non-construction, we assumed that there was no area transformed from the agricultural land. bThe ratios of 38.7%, 8.2%, 3.4%, 40%, and 9.7% for AL, industrial land (IL), commercial land (CL), other land for construction (OLC), and ONLC, respectively, in the S3 columns are from the draft plan. c The time spans from 2040 to 2050 were set according to different construction speeds (CSs), and the corresponding ratios of each type of land use were kept constant during the period
As in the current study, we mainly care about different land use types, and climate change is deemed as an external variable that will exert the same influences to all land use change scenarios
Summary
Urbanization is proceeding rapidly in several developing countries such as China [1,2]. Urbanization induces an increase in the local population and increases in socioeconomic activities, which in turn increase the generation of waste and pollutants in catchment areas [15] These two mechanisms are further influenced by different planning choices regarding Land Use Intensity (LUI) and Construction Speed (CS). Many distributed and physically based watershed models, such as the water management model (SWMM) [20], the soil and water assessment tool (SWAT) [21,22], the hydrological simulation program–fortran (HSPF) [23], etc., have been used for assessing NPS pollution and show advantages in revealing the subtle physical mechanisms in terms of the rainfall-runoff process, soil erosion and the sediment transport process, pollutant migration and the transformation process, etc [24] To assess these processes, a large number of continuous and synchronous data with respect to non-point source runoff and pollution are needed to make precise parameter estimations [25], this type of data is quite scarce in China. The findings are expected to assist in the decision-making process of local governments concerning the sustainable construction of small towns
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