Spatiotemporal Evolution Analysis and Future Scenario Prediction of Rocky Desertification in a Subtropical Karst Region

Landscape change is a dynamic feature of landscape structure and function over time which is usually affected by natural and human factors. The evolution of rocky desertification is a typical landscape change that directly affects ecological environment governance and sustainable development. Guizhou is one of the most typical subtropical karst landform areas in the world. Its special karst rocky desertification phenomenon is an important factor affecting the ecological environment and limiting sustainable development. In this paper, remote sensing imagery and machine learning methods are utilized to model and analyze the spatiotemporal variation of rocky desertification in Guizhou. Based on an improved CA-Markov model, rocky desertification scenarios in the next 30 years are predicted, providing data support for exploration of the evolution rule of rocky desertification in subtropical karst areas and for effective management. The specific results are as follows: (1) Based on the dynamic degree, transfer matrix, evolution intensity, and speed, the temporal and spatial evolution of rocky desertification in Guizhou from 2001 to 2020 was analyzed. It was found that the proportion of no rocky desertification (NRD) areas increased from 48.86% to 63.53% over this period. Potential rocky desertification (PRD), light rocky desertification (LRD), middle rocky desertification (MRD), and severe rocky desertification (SRD) continued to improve, with the improvement showing an accelerating trend after 2010. (2) An improved CA-Markov model was used to predict the future rocky desertification scenario; compared to the traditional CA-Markov model, the Lee–Sallee index increased from 0.681 to 0.723, and figure of merit (FOM) increased from 0.459 to 0.530. The conclusions of this paper are as follows: (1) From 2001 to 2020, the evolution speed of PRD was the fastest, while that of SRD was the slowest. Rocky desertification control should not only focus on areas with serious rocky desertification, but also prevent transformation from NRD to PRD. (2) Rocky desertification will continue to improve over the next 30 years. Possible deterioration areas are concentrated in high-altitude areas, such as the south of Bijie and the east of Liupanshui.

RESEARCH OF A LATERAL REAMER BIT FOR DIGGING PLANTING HOLE IN ROCKY ABANDONED MINE AREA

In the abandoned mine area with Karst landform in China, soils are few and thin but rocks are common, traditional planting hole diggers are unequal to work in rocks for vegetation restoration. A reamer bit with variable lateral drilling radius was designed based on the PDC (polycrystalline diamond compact) bit technology and metamorphic mechanism. Two lateral camber blades with PDC teeth were installed inside the bit body, a screw mechanism was employed as the actuation and a spatial double triangle mechanism was taken for the transmission. The curve of the camber blade was specially defined thus the reaming load was decentralized to 85.7% teeth on the blade. The kinematics of the lateral reamer bit was analysed, the mapping models from the actuation to the reaming radius and speed were established. Concrete samples were reamed indoors from 240mm to 407mm in diameter, the reaming cutting load and time length were measured and analysed. The lateral reamer bit was approved with the experiment results, this study provided equipment support for digging the planting hole in rocky abandoned mine areas and also expanded the PDC bit application.

Assessment of Groundwater Vulnerability using COP Method to Support the Groundwater Protection in Karst Area

The karst landform holds considerable water resource potential and is known for its underground rivers. On the other hand, the high porosity carbonate rocks on this landform cause the decrease of the natural protection function against groundwater pollution. Hence, the analysis of groundwater vulnerability in the karst area is prominent before making the spatial planning regulation. This recent study aimed to analyze the groundwater vulnerability in the karst area located in a part of Umbulrejo Village, Yogyakarta, Indonesia, and proposed action in groundwater protection. The method used in this research was based on the COP method. The data acquisition was conducted by survey method both for primary and secondary data. The COP (Concentration of flow, overlaying layers, and precipitation) analysis was supported by ArcGis software. The analysis of groundwater vulnerability showed that there were two vulnerability classes, i.e., very high (48.6%) and high (51.4%). These results were influenced mainly by the close distance of the recharge area to swallow holes and the lithology type (karst), which contributed to a very high value in reducing protection against groundwater. A proposed action to support groundwater protection is regulating the land utilization in the area of the settlements.

Theoretical analysis on stress distribution characteristics around a shallow buried spherical Karst cave containing fill materials in limestone strata

The prime objective of the article is to present the spatial characteristics of stress distribution around a shallowly buried spherical Karst cave containing fill materials in limestone strata. Firstly, considering the external load effects, stress field in the Earth’s crust, internal filling, and the Karst landform characteristics in China, a spatial axial-symmetrical model was established. Concurrently, combining available work and the concept of elasticity, the boundary conditions were determined. Subsequently, Love displacement method was introduced, in addition to the expressions of stress components were gained. The diagram characteristics of each stress component were summarized, which are affected by various influencing factors. Finally, in order to prove the rationality of the general solution, a comparison between numerical simulation result and theoretical calculation result was carried out, as well as the maximum error between theoretical calculation value and numerical simulation value is less than 5%. Thus, the analytical solution could represent the spatial characteristics of stress distribution around a shallowly buried spherical Karst cave containing fill materials in limestone strata.

Nutritional Composition and Mineral Elements Content Analyses of Lonicera fulvotomentosa Hsu et S. C. Cheng Grown in China

Lonicera fulvotomentosa Hsu et S. C. Cheng (L. fulvotomentosa), a vine shrub found in Southwestern China, is used for treating epidemic fever and infectious diseases, such as SARS and Avian Influenza. Here, we investigated the chemical composition and nutritional content of dried flowers of L. fulvotomentosa grown in yellow loam and Karst landform soil in Guizhou, China. The moisture content in all samples varied from 3.25 to 3.63%, lipids from 7.76 to 9.93%, fiber from 6.93 to 7.34%, ashes from 12.32 to 12.76%, crude protein from 7.85 to 8.53%, and carbohydrates from 56.21 to 59.77%. Using inductively coupled plasma-mass spectroscopy (ICP-MS), the predominant mineral elements in the dried flowers were found to be calcium (297.34-351.26 mg/kg), potassium (132.56-140.37 mg/kg), iron (37.77–41.25 mg/kg), and magnesium (9.47–11.36 mg/kg). Also, HPLC identified flavonoids (kaempferol, rutin, quercetin, luteolin, and apigenin) and phenolic acids (caffeic acid, gallic acid, and chlorogenic acid). Thus, the chemical composition of L. fulvotomentosa was similar to that of Lonicera japonica Thunb. (L. japonica). Thus, it could be used as an alternative to L. japonica. Our results showed that the dried flower of L. fulvotomentosa had an extremely high content of chlorogenic acids and caffeic acid, which could be developed as a candidate molecule as HIV inhibitors.

Origin of the low-medium temperature hot springs around Nanjing, China

The exploration of the origin of hot spring is the basis of its development and utilization. There are many low-medium temperature hot springs in Nanjing and its surrounding karst landform areas, such as the Tangshan, Tangquan, Lunshan, and Xiangquan hot springs. This article discusses the origin characters of the Lunshan hot spring with geological condition analysis, hydrogeochemical data, and isotope data. The results show that the hot water is SO4–Ca type in Lunshan area, and the cation content of SO4 is high, which are related to the deep hydrogeological conditions of the circulation in the limestone. Carbonate and anhydrite dissolutions occur in the groundwater circulation process, and they also dominate the water–rock interaction processes in the geothermal reservoir of Lunshan. The hot water rising channels are deeply affected by the NW and SN faults. Schematic diagrams of the conceptual model of the geothermal water circulation in Lunshan are plotted. The origin of Tangshan, Tangquan, and Xiangquan hot springs are similar to the Lunshan hot spring. In general, the geothermal water in karst landforms around Nanjing mainly runs through the carbonate rock area and is exposed near the core of the anticlinal structure of karst strata, forming SO4–Ca/SO4–Ca–Mg type hot spring with the water temperature less than 60°C. The characters of the hot springs around Nanjing are similar, which are helpful for the further research, development, and management of the geothermal water resources in this region.