Weijun Zhao

Non-homogeneous soil’s high gravel content (also known as the “soil-rock dual structure”) may render it more prone to erosion and the significant development of gullies. In order to reveal the morphological characteristics and erosion rate of gullies in “soil-rock dual structure” areas, this study focused on the Shagou Reservoir basin in the Yimeng mountain area as the study area. Based on a complete digital orthophoto map (DOM, 0.03 m) and a digital elevation model (DEM, 0.03 m) acquired by an unmanned aerial vehicle (UAV), the researchers calculated the length (L), top width (TW), depth (D), area (A) and volume (V) of 19 gullies and built and optimized the volume estimation model. The DOM and the DEM were used to modify the morphological parameters of 43 gullies extracted from high-resolution remote sensing (RS) stereopair images (Worldview, 0.5 m), and the development and evolution of gully erosion were evaluated in large scale. The results showed that: (1) after correction, the average relative errors of parameters L, TW, D and A computed from the UAV data and the high-resolution RS stereopair image data fell below 0.005%; (2) the mean of TW/D was 5.20, i.e., the lateral erosion development of gullies far outweighed the downcutting erosion. The retrogressive erosion, lateral erosion and downcutting erosion rates of gullies were 0.01~0.83 m/a (averaged at 0.23 m/a), 0.01~0.68 m/a (averaged at 0.25 m/a) and 0.01~0.19 m/a (averaged at 0.09 m/a), respectively, between 2014 and 2021; (3) the volume-area (V-A) model for gullies is the optimal one (p < 0.01, R² = 0.944).A total of 90.7% of the gully volume was growing at an erosion rate of 0.42~399.39 m³/a and the total erosion rate of the gullies was 3181.56 m³/a from 2014 to 2021. These research findings can serve as a basis for the quantitative modeling of gully erosion in water-eroded locations with a large-dimension “soil-rock dual structure”.

Ecosystem services value (ESV) has been one index of quantitative evaluation for the ecological livability of heavy industry cities in the new era, which is intimately relevant to patterns of spatio-temporal changes in land use. This study aims to reveal the response of ecosystem service value in heavy industrial cities to the spatial-temporal evolution structure of land use and to analyze the cold and hot spots and sensitivity. In this study, Taiyuan was taken as an example, and Landsat images were adopted as the basic data. This study used intensity analysis, revised ESV, fishing nets, sensitivity analysis, and the methods of hotspot analysis and spatial overlay. The results showed as follows, (1) The characteristics of land use structure evolution mainly focus on the increase of construction land in the early and the rapid development stage of heavy industry cities. All land use types were partly transferred to construction land, but farmland was the main source, with the largest change intensity in the rapid development stage in Taiyuan; (2) The low-value zones of ESV were mostly distributed in the main urban area for construction and farmland, while the high-value zones were primarily distributed in the forestland and grassland. They were distributed in the Fenhe River valley, western and northern mountainous and hilly areas of Taiyuan. The total ESV continued to decline from 2003 to 2018, with a loss amount of RMB 29 million; (3) The patches of land use change were more and more broken, and the spatial distribution of the cold and hot spots was more and more dispersed. The cold and hot spots of ESV were concentrated in the eastern main urban area and its surrounding areas and expanded to the north and south; (4) The forestland was the most sensitive land factor of ESV. The study provides a theoretical method for land use planning, environmental governance, and ecological restoration in heavy industry cities in the new era.

Loess Plateau is the key construction area of ecological environment restoration in China. Since implementing the project of converting farmland to forests, the land use structure and existing problems in the loess area of northern Shaanxi have received extensive attention. Land use structure is the area and proportion of all kinds of land within a certain area, which determines the play of regional functions and land use benefits. This work took Wuqi County, Loess District, Northern Shaanxi, the demonstration county of national project of converting farmland to forests. Based on the land use data of Wuqi County in Loess Ddistrict of north Shaanxi Province in 2009, this work carried out the quantitative analysis and discussion of land use quantitative structure in this area by means of quantitative geographical model and GIS spatial analysis and by using indexes such as diversification, centralization and combination coefficient of ground class. The results show that the quantity and structure of land use in Wuqi County are diversified, the concentration is low, and the complete degree of land use type is high. Additionally, the land combination type is mainly forestland-grassland, and the overall function needs to be improved. This study can provide reference for the quantitative analysis of land use structure in similar areas and counties.

As a special form of tourism, ecotourism is one of the important factors to realize the sustainable development of tourism. The relationship between ecological environment and tourism development is not very clear. Based on the development of forestry resources and using the methods of linear regression and correlation analysis, this study analyzed the development of tourism industry in Tai’an, such as forestry production, tourism reception volume, and the relationship between them. The results showed that: (1) the area of forestry resources in Tai’an was increasing at an annual rate of 37.4%; (2) during 2004-2009, the proportion of the tertiary industry in the GDP of Tai’an increased from 34.19% to 35.57%, and the tourist reception increased by 22.2% year on year; (3) there was a significant linear correlation between forestry resources and tourism development, and the functional relationship between them was y = 0.0383x - 2965.5, R² = 0.874. The results of this study can provide scientific reference for the sustainable development of ecotourism in Tai’an.

Wetland, ocean, and forest are regarded as the world’s three major systems. Among them, wetland has always been regarded as one of the signs of sustainable development of urban ecological environment. Therefore, its ecological problems, rational development and protection have become the focus of the sustainable development of wetlands and even cities. This study took wetlands in 17 cities in Shandong Province as the research object, then collected relevant data on the area of various types of wetlands in Shandong Province in 2008 and 2013 and analyzed the changing trend of wetland area in Shandong Province in recent 5 years by using methods including multivariate statistics and GIS space analysis, and raised some ecological problems at the same time. The results showed that: 1) In terms of time, the wetland area in Shandong Province has been reducing in the past five years. Compared with 2008, the wetland area in Shandong Province decreased by 24.57% in 2013; 2) In terms of space, the wetland area in coastal areas was seriously degraded, with a reduction rate of more than 50%; 3) In terms of wetland types, natural wetlands such as lakes and rivers were decreasing year by year. They have respectively reduced by 1.02×105 hectares and 4.21×105 hectares while the artificial wetland has increased by 5.33×105 hectares, which means some natural wetlands have been converted into artificial wetlands. The most obvious was the construction of wetland parks; 4) There were a series of ecological problems in the wetlands in Shandong Province, such as blind reclamation and deterioration of the quality of water resources.

Data research in recent decades shows that drought and flood disasters occur frequently in China due to the uneven spatial and temporal distribution of rainfall. Taking Shandong Peninsula as an example, this work selected the standard precipitation index (SPI) as the precipitation characteristic analysis index, calculated the SPI values at 4 different time scales in multiple meteorological stations from 1961 to 2013, and analysed the inter annual and seasonal variation characteristics of drought and flood. The results show that: (1) the standardized precipitation index can better reflect the characteristics of inter annual and seasonal drought and flood changes in the study area on a long time series scale. (2) The most flood period occurred in 1964 and 2007, and the most drought period occurred in 1981, 1991 and 1998, and all reached the severity of extreme drought. (3) The intensity of drought and flood varied in different time scales. In spring, autumn and winter, the drought intensity and affected area showed a decreasing trend. However, the flood intensity and its affected area were on the rise in summer, and the rainfall intensity was on the rise in time scale.