Several years ago an advertisement appeared in the real estate section of the Washington Post 1 promoting a new development: “The NICE THING about the city is that it eventually ENDS” (emphasis in original). The image juxtaposed sidewalks, a fire hydrant, and other essentially gray surfaces in the foreground (bad) with the bucolic images of forest and farm field in the distance (good). The implications were clear —if you want any meaningful ex posure to nature, quickly exit the city. Unfortunately, this reflects the popul ar attitude toward cities and nature.

The Nature of (in) Cities

Urbanization impact on landscape patterns in Beijing City, China: A spatial heterogeneity perspective

The spatial characteristics and relationships between landscape pattern and ecosystem service value along an urban-rural gradient in Xi’an city, China

Effects of urbanization on direct runoff characteristics in urban functional zones.

Axial and visibility graph analysis models are combined with GIS and Space Syntax to study the corresponding relationship between street network and specific city life in Hankou, China, based on three scales - city, district, and community, so as to interpret the hidden structure out of complex urban form through the spatial logic of street network. In this paper, a quantitative analysis is made on selected parameters in Space Syntax, including Integration, Choice, density of road, and Ht index. The result indicates that there is certain correlation among these parameters. Moreover, these parameters also present certain changing patterns along with the increase of analysis radius. The results reveal that the street network of Hankou presents a multi-hierarchical structure and spatial wholeness from all these three scales. This characteristic creates vitality and diversity while maintaining the feature of wholeness for the urban space. Research has turned out that community-scale street network performs a positive role to keep neighborhoods alive. Therefore, it is an important strategy for maintaining the vitality of urban space and realizing coordination and unification between parts and the whole. It is proposed in this paper that a good street network is a key factor for carrying forward urban context of Hankou. Undoubtedly, it is worthy of reflecting on large-scale demolition of existing urban space, especially in historical areas. Afterwards, the paper proposes a hierarchically synergetic planning strategy based on the analysis. More attention should be paid to street network to preserve diversity, continuity, and integrity, and finally archive holistically sustainable development within a city.

Assessment of lively street network based on geographic information system and space syntax

Non-point source (NPS) pollution has become a major source of water pollution. A combination of models would provide the necessary direction and approaches designed to control NPS pollution through land use planning. In this study, NPS pollution load was simulated in urban planning, historic trends and ecological protection land use scenarios based on the Conversion of Land Use and its Effect at Small regional extent (CLUE-S) and Soil and Water Assessment Tool (SWAT) models applied to Hunhe-Taizi River Watershed, Liaoning Province, China. Total nitrogen (TN) and total phosphorus (TP) were chosen as NPS pollution indices. The results of models validation showed that CLUE-S and SWAT models were suitable in the study area. NPS pollution mainly came from dry farmland, paddy, rural and urban areas. The spatial distribution of TN and TP exhibited the same trend in 57 sub-catchments. The TN and TP had the highest NPS pollution load in the western and central plains, which concentrated the urban area and farm land. The NPS pollution load would increase in the urban planning and historic trends scenarios, and would be even higher in the urban planning scenario. However, the NPS pollution load decreased in the ecological protection scenario. The differences observed in the three scenarios indicated that land use had a degree of impact on NPS pollution, which showed that scientific and ecologically sound construction could effectively reduce the NPS pollution load in a watershed. This study provides a scientific method for conducting NPS pollution research at the watershed scale, a scientific basis for non-point source pollution control, and a reference for related policy making.

Combining CLUE-S and SWAT models to forecast land use change and non-point source pollution impact at a watershed scale in Liaoning Province, China

As urbanization increases, urban runoff becomes an increasingly more important component of urban non-point pollution. In this study, the Storm Water Management Model was used to simulate the quantity and quality of runoff in a highly urbanized catchment. Data from three rainfall events were collected and used for model calibration and validation. Model performance was assessed using the Nash-Sutcliffe coefficient, relative error, and coefficient of determination. The modified Morris screening method was used for local sensitivity analysis. Sensitivity analysis results showed that the destore imperv and condit roughness parameters had the most influence on the hydrology and hydraulic module. Road exponent was the most sensitive parameter in determining TSS quantity and peak concentration. The calibration and verification results indicated that the model structure and parameters fitted the runoff-producing pattern. The total simulation accuracies of TSS, TN, TP, and COD loads, as assessed by the R2 value, were 0.82, 0.87, 0.72, and 0.94, respectively.

http://www.pjoes.com/pdf-60721-23786?filename=Modeling the Quality and.pdf

Modeling the quality and quantity of runoff in a highly urbanized catchment using Storm Water Management Model.

Characterization and first flush analysis in road and roof runoff in Shenyang, China.

Analyzing spatiotemporal characteristics of the historical urbanization process is essential in understanding the dynamics of urbanization and scientifically planned urban development. Based on historical urban area maps and remote sensing images, this study examined the urban expansion of Shenyang from 1910 to 2010 using area statistics, typology identification, and landscape metrics approaches. The population and gross domestic product were analyzed as driving factors. The results showed that the urban area of Shenyang increased 43.39-fold during the study period and that the growth rate has accelerated since the 1980s. Three urban growth types were distinguished: infilling, edge-expansion, and spontaneous growth. Edge-expansion was the primary growth type. Infilling growth became the main growth type in the periods 1946–70, 1988–97, and 2004–10. Spontaneous growth was concentrated in the period of 1997 to 2000. The results of landscape metrics indicate that the urban landscape of Shenyang originally was highly aggregated, but has become increasingly fragmented. The urban fringe area was the traditional hot zone of urbanization. Shenyang was mainly located north of the Hun River before 1980; however, the south side of the river has been the hot zone of urbanization since the 1980s. The increase of urban area strongly correlated with the growth of GDP and population. Over a long time scale, the urbanization process has been affected by major historical events.

/pdf/a-century-of-the-evolution-of-the-urban-area-in-shenyang-4x5omudv8y.pdf

A Century of the Evolution of the Urban Area in Shenyang, China

In order to improve the accuracy of dust storm prediction and reduce the damage and losses by a dust storm event, it is necessary to conduct an in-depth study on the same. The data of the national air quality stations, backward trajectories generated by the Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT), and the lidar network data from Wuwei, Baiyin, and Dingxi were used to study a large-scale dust storm event that occurred from 12 to 14 May 2019. This study explores the cause of the dust storm and physical characteristics of dust aerosols in three-dimensional space, as well as its impact on air quality. Results show that the dust storm was caused by the eastward movement of the East Asian trough and affected most cities in northern China from northwest to southeast. Consequently, the air quality deteriorated seriously, especially over the Hexi Corridor. The hourly peak concentrations of PM10 in Wuwei and Baiyin were close to 3,000 μg·m−3. The observations from the lidar network show that the dust intensities were similar at different cities, and their extinction coefficients were close. However, the depolarization ratio varied with sources and the physical characteristics of dust particles. According to the simulation results of extinction coefficients and particle concentrations, due to the impact of dust transported at high altitudes, the concentration of particles in Dingxi did not decrease with the increase in altitude. The particle concentrations from ground-based monitoring were lower than those of Baiyin and Wuwei, while particle concentrations above 0.3 km were higher than those of Baiyin and Wuwei.

/pdf/comprehensive-analysis-of-a-dust-storm-by-a-lidar-network-2o8fmkha.pdf

Yanyan Xu

Papers

Combining CLUE-S and SWAT models to forecast land use change and non-point source pollution impact at a watershed scale in Liaoning Province, China

Modeling the quality and quantity of runoff in a highly urbanized catchment using Storm Water Management Model.

Characterization and first flush analysis in road and roof runoff in Shenyang, China.

A Century of the Evolution of the Urban Area in Shenyang, China

Comprehensive Analysis of a Dust Storm by a Lidar Network Combined With Multiple Data