Exploring the impact of urban form on urban land use efficiency under low-carbon emission constraints: A case study in China's Yellow River Basin.

In the Urban Anthropocene, how to meet the demands of growing urban populations on limited urban land is a key global challenge. Unreasonable urban planning and land use has brought about undesirable consequences including huge carbon emissions. However, research on the spatial impact of urban form on urban land use efficiency (ULUE) under low-carbon emission constraints is limited. This study analyzes 91 cities located in China's Yellow River Basin (YRB). First, we define a new comprehensive indicator system to measure ULUE under low-carbon constraints using the SBM-UN model. We then select nine landscape indicators to quantify the sprawl, complexity, and aggregation of urban form. Finally, we use Spatial Durbin Model to reveal the relationship between urban form and ULUE. We find that carbon emissions in the YRB increased steadily during the study period. The average value of ULUE increased from 0.469 in 1994 to 0.772 in 2018. Efficiency improved most in the provinces of Shaanxi, Henan, Ningxia, and Shandong, with growth rates of 234.15%, 102.40%, 93.09%, and 66.24%, respectively. Positive global Moran's I indices suggest that the spatial distribution of ULUE is positively correlated at basin level. Moreover, urban form metrics in the YRB demonstrated significant regional differences from 1994 to 2018. The regression results showed irregular urban form can negatively impact ULUE while compact and aggregated urban forms can improve ULUE under low carbon constrains. In addition, there are both positive and negative correlations between urban sprawl and ULUE in different regions. Today's choices on urban form can restrict the development pattern of cities and lock in pathways of carbon emissions in the future. Based on the findings in this study, the government should pursue optimal city sizes, avoid scattered patterns and aim for compact urban form.