Land Use and Land Cover Dynamics in the Eseka Alluvial Gold Mining District, Centre Region, Cameroon

Local populations in Cameroon thrive on forest resources and the flow of ecosystem services they provide are pivotal in sustaining national economy, improving people’s lives, safeguarding biodiversity, and mitigating the impacts of environmental changes. The exploitation of these resources invariably leads to deforestation and forest degradation. This study was designed to evaluate land use land cover change (LULCC) in the Eseka alluvial gold mining district with the aid of Landsat images. In the investigation of forest cover change, four Landsat satellite images for (1990, 2002, 2015 and 2022) were used. Ground-truthing also helped to identify the activities carried out by the local population and to determine agents, drivers and pressures of land use and land cover change. Four main land cover classes namely: forest, agricultural land, settlement/mining camps and water bodies were selected. Between 1990 and 2022, the proportion of forest decreased from 98% to 34% while those of agricultural land and settlement/mining camps increased from 2% to 60% and 0.54% to 6% respectively. Analysis showed ongoing deforestation with forest cover loss of ~98,263 ha in 32 years giving a cover change percentage of 63.94%. Kappa coefficient for the study period ranged from 0.92 to 0.99. Forest cover loss could be attributed to farming activities, wood extraction and alluvial gold mining activities. Economic motives notably the need to increase household income from a frequent demand for farm and wood products in neighbouring towns and the quest for gold were the main drivers of these activities. Hence, this study assesses the impact of human activities from the mining sector on the forest ecosystem in a bid to inform mitigation policies.

Evaluation Study on the Reclamation Suitability of Occupied Land in the Coal Mine Area——Taking Gouchang Coal Mine in Nayong County of Guizhou as An Example

The suitability evaluation of reclamation land was the premise and foundation for drawing up the land reclamation program.Taking Gouchang coal mine in Nayong County of Guizhou as an example,combining with the actual situation which included the topography,the soil in the mine area and so on,the reclamation land in the mine area was divided into the living area,the production area,the coal yard,the temporary coal gangue yard and other subsidiary facilities district.It determined that the main destruction type in every unit was the occupation,and the destruction degree was severe.Meanwhile referring the suitability evaluation standards of cultivated field and woodland,it finally determined that the reclamation direction of evaluation land which was damaged seriously by the occupation in the mine area was all suitable to the cultivated field and woodland.

Suitability evaluation for land reclamation in mining area:A case study of Gaoqiao bauxite mine

Suitability evaluation plays an important role in land reclamation because the choice of evaluation methods affects the accuracy and objectivity of the suitability evaluation results. Furthermore, it influences the decision-making related to land reclamation. An improved method, which is called limit comprehensive conditions method, was developed after different suitability evaluation methods were studied. Based on this method, the reclaimed land of the Gaoqiao bauxite mining area was evaluated. The Gaoqiao mining area was divided into seven evaluation units that were evaluated respectively by selecting evaluation factors and establishing grade standards. The results show that the proposed method is more applicable and easier to handle. Moreover, its evaluation results are more scientific compared with the traditional evaluation methods. The improved method can be beneficial to the rapid monitoring and the effective management of reclaimed land in the opencast mine area.

Zoning of land reclamation in coal mining area and new progresses for the past 10 years

Coal mining disturbed land is the main sources of land reclamation in China.With the rapid increase of economy and coal production,more and more land has been disturbed by construction and coal mining;thus,land reclamation has become highlights in the past 10 years,and China is boosting land reclamation in mining areas.Disturbance characteristics vary from region to region,according to natural and geological conditions,coal mining area land reclamation was divided into 3 zones,which are eastern,western and southern.Reclamation strategies are focused on prime farmland protection in eastern and ecological restoration in western and southern zones,respectively.Several innovative reclamation technologies and theories for the past 10 years were introduced in this paper,including concurrent mining and reclamation,Yellow river sediments backfilling,self-reclamation,and topsoil alternatives in opencast mines.Besides,in the government regulation and legal system building respect,several important laws and regulations were issued and implemented in the past 5 years,promoting land reclamation management and supervision greatly.Land reclamation is and will still be one of the most important parts of coal industry in the future,and more efforts and funds are expected to get involved.

Mining Weights of Land Evaluation Factors Based on Cloud Model and Correlation Analysis

The veracity of land evaluation is tightly related to the reasonable weights of land evaluation fac- tors. By mapping qualitative linguistic words into a fine-changeable cloud drops and translating the uncertain factor conditions into quantitative values with the uncertain illation based on cloud model, and then, inte- grating correlation analysis, a new way of figuring out the weight of land evaluation factors is proposed. It may solve the limitations of the conventional ways.

Comprehensive study on ecological restoration and land exploitation of mining subsidence in suburbs of Chinese mining cities

China has nearly a hundred mining cities derived from mining development.While mining development has brought about immense achievements in a city’s economic construction,it has also resulted in different levels of damage to the eco-environment of the mining city,leaving behind a lot of subsided wasteland and heavily confining the sustainable development and transformation there.How to restore and exploit the land and eco-environment disrupted by mining development in an effective way,therefore,has become a pressing challenge that Chinese mining cities are facing.In this paper,the planning and construction of Nanhu Eco-city in the suburb of Tangshan City is analyzed as an example.After characterizing the coal-mining subsided lands in Kailuan Tangshan Mine originated in different periods and under different geological mining conditions and evaluating their safety level,the authors try to demonstrate how eco-restoration and comprehensive land exploitation should be implemented by making the best use of available local resources to achieve "economy-society-environment" sustainability and coexistence in a mining city.

DEVELOPMENT OF A DATA MINING METHOD FOR LAND CONTROL

Land resources are facing crises of being misused,especially for an intersection area between town and country,and land control has to be enforced.This paper presents a development of data mining method for land control.A vector_match method for the prerequisite of data mining i.e., data cleaning is proposed,which deals with both character and numeric data via vectorizing character_string and matching number.A minimal decision algorithm of rough set is used to discover the knowledge hidden in the data warehouse.In order to monitor land use dynamically and accurately,it is suggested to set up a real_time land control system based on GPS,digital photogrammetry and online data mining.Finally,the means is applied in the intersection area between town and country of Wuhan city,and a set of knowledge about land control is discovered.

Soil Heavy Metal Pollution and Health Risk Assessment of Abandoned Land in Coal Mining Areas in Xingren County

Total contents of heavy metals （ Pb, Cr, Cd, Hg, As, Cu, Zn, and Ni） in 68 soil samples were determined to evaluate the contamination level of soil from five coal mine areas in Xingren County, Guizhou province. The pollution levels of heavy metals were characterized by anthro- pogenic influence multiple, and the pollution of heavy metal in soil was evaluated using geo-accumulation index. Based on the health risk models recommended by the U.S. Environmental Protection Agency （ US EPA）, the health risks of heavy metals in the soils were assessed. The results showed that the abandoned land in the five coal mining areas were contaminated by heavy metals, and the order of pollution levels of eight heavy metals was As 〉 Pb 〉 Cu 〉 Hg 〉 Ni 〉 Cr 〉 Cd 〉 Zn. The soils suffered moderate-heavy pollution from As and Pb, and the contents of As and Pb in the soils were 13.16 and 4.76 times higher than the background values of Guizhou Province, followed by Cu, Hg and Ni , while soil pollution from Cr, Cd and Zn was mild. The order of non-caminogenic risks of the heavy metals in the soils was As 〉 Pb 〉 Cr 〉 Ni 〉 Cu 〉 Hg 〉 Cd 〉 Zn, and the non-carcinogenic dsk value of As was higher than that its threshold value 1, which indicated that As had a high potential health risk to adults and children. The order of carcinogen risks of the four heavy metals was As 〉 Cd 〉 Cr 〉 Ni, and the carcinogenic risk value of As was higher than its threshold value, indicating that As had a high carcinogenic risk to adults and children. The carcinogenic risk values of other three heavy metals （ Cd, Cr and Ni） were lower than the threshold value, so they had no carcinogenic risk to human health. Moreover, children were more sensitively affect- ed by heavy metals from the abandoned land. Therefore, the health of children in such areas should be paid more attention to. The HI value of the eight heavy metals to children was seven times higher than that to adults. The contribution rate of HQAs to HI was about 88%, and the contribution rate of CRA, to TCR was about 98%, so As was the most crucial factor influencing non-carcinogenic and carcinogenic dsk in the abandoned soils.

Assessment of several typical physical properties of reclaimed farmland filled with Yellow River sediment in Jining, China

Land subsidence caused by underground coal mining is one of the most prominent environment problems in China. The reclamation of mining subsidence land with Yellow River sediment was considered to be feasible, but its effectiveness needs to be verified. An integrated reclamation technology with Yellow River sediment was evaluated using a comparison of actual crop production soil profile analysis in Jining City, China. The results indicated that reconstructed soil profile of the reclaimed farmland was less effective in retaining water and in supporting plant growth than that of the unaltered farmland. Some measures are proposed, such as reducing the drainage velocity to allow sedimentation and retention of the clay and silt, changing the techniques of filling the Yellow River sediment and increasing the organic matter content in the soil layers to improve the capacity to retain water in the reclaimed farmland.

Role of the different planting age of seabuckthorn forests to soil amelioration in coal mining subsidence land

To investigate the effects of seabuckthorn(Hippophae rhamnoides)on soil amelioration,using the space replacement method,soil physical and chemical indexes as well as the microorganism quantity and soil enzyme activities were analyzed.The results showed that:the soil bulk density of surface soil decreased and soil porosity and field capacity increased after afforestation with seabuckthorn.The plant was found to effectively reduce the soil pH,increase the soil conductivity,soil organic matters and available nutrients.Soil microorganism quantity,soil enzyme activities were both higher in 0-20 cm layer than in 20-40 cm layer.With the increase years of remediation with seabuckthorn,the quantity of soil microorganism and enzyme activities were increasing to a higher level 5 to 8 years later.Our study indicates that seabuckthorn can effectively improve soil physical and chemical properties,increase the quantity of soil microorganisms and enzyme activities,which is of great significance for the ecosystem restoration in mining areas.

Effect of coal resources development and compensation for damage to cultivated land in mining areas

The exploitation of coal resources inevitably affects, to different degrees, arable land resources and impacts the socio-economic development in mining areas. Therefore it is of great practical importance to probe the rules of the effect from coal resource exploration on arable land. Suitable and effective measures to compensate for damaged to and loss of arable land resources should be taken on the basis of carrying out green mining and reducing damage to limited arable land resources. We have used GIS in simulating the effect of coal resource exploration on arable land. In light of our simulation of the space-time spectrum, the effect is analyzed. Given the socio-economic development conditions of a mining area, specified rational amounts and opportunities for compensation to arable land in mining areas are explored. Finally, from a policy perspective, relevant proposals for rational arable land resource compensation are proposed to facilitate the coordinated development between coal resource exploitation and socio-economy development in mining areas.

KEY TECHNOLOGY OF D-INSAR AT X-BAND FOR MONITORING LAND SUBSIDENCE IN MINING AREA AND ITS APPLICATION

In theory, land subsidence measurement results with high accuracy can be obtained by using the Differential Interferometry Synthetic Aperture Radar(D-InSAR) at X-band. In practice, however, the measuring accuracy of D-InSAR at X-band has been seriously affected by some factors, e.g., decorrelation and high deformation gradient. In this work, the monitoring capability of D-InSAR for coal-mining subsidence is evaluated by using SAR data acquired by TerrraSAR-X system. The SAR image registration method for low coherence image pairs, the denoising phase filter for high noise level interferogram and atmospheric effects mitigation method are the key technical aspects which directly influence the measurement results of D-InSAR at X-band. Thus, a robust image registration method, an improved phase filter method and an atmospheric effects mitigation method are proposed in this paper. The proposed image registration method successfully achieves InSAR coregistration, while the amplitude cross-correlation cannot properly coregister low coherence SAR image pairs. Moreover, the time complexity of the proposed image registration method is obviously slighter than that of the Singular Value Decomposition(SVD) method. The comparing experiment results and the unwrapping phase results show that the improved Goldstein filter is more effective than the original Goldstein filter in noise elimination. The atmospheric influence correction experiment results show that the land subsidence areas with atmospheric influence correction are more clarified than that of without atmospheric influence correction. In summary, the presented methods directly improved the measurement results of D-InSAR at X-band.

Stakeholder orientated sustainable land management:The Ruhr Area as a role model for urban areas

The concept of sustainable land management(SLM)can help create a balance between the different demands of economy,society and nature.SLM means to actively develop land based on a knowledgebased procedure.It should aim on long term enhancements.The basis of SLM is the interests and the goals of the stakeholders.It is the result of a bargaining process between different institutions by creating win-win-situations or adequate conflict solutions to reach a consensus.The Ruhr Area is Germany’s biggest metropolitan area.Land management regarding economic,social and environmental issues,which has a long tradition in this area,goes back to 1920.Being the centre of the heavy industry in Germany for more than 150 years,the Ruhr Area today is a green metropolis.The ecological,social and economical change of this industrial region can serve as a role model for SLM in urban areas all over the world.

Extracting mining subsidence land from remote sensing images based on domain knowledge

Extracting mining subsidence land from RS images is one of important research contents for environment monitoring in mining area. The accuracy of traditional extracting models based on spectral features is low. In order to extract subsidence land from RS images with high accuracy, some domain knowledge should be imported and new models should be proposed. This paper, in terms of the disadvantage of traditional extracting models, imports domain knowledge from practice and experience, converts semantic knowledge into digital information, and proposes a new model for the specific task. By selecting Luan mining area as study area, this new model is tested based on GIS and related knowledge. The result shows that the proposed method is more pre- cise than traditional methods and can satisfy the demands of land subsidence monitoring in mining area.

Analysis to driving forces of land use change in Lu’an mining area

By selecting impact factors of driving force and formulating evaluation criteria of the impacts, the evaluation system of corresponding driving force impact of land use change was established. Taking Lu'an mining area as an example, the specific impact factors of coal mine were comprehensively evaluated and analyzed in order to carry out qualitative and quantitative analysis for the driving force of mining-land use change. The principal component analysis shows that the social and economic development in mining area from 2000 to 2007 demonstrates continuous accelerate trends, and the impacts of its overall driving force to land use change are increased gradually. The socio-economic factors have more impacts to mining-land use change than those of the natural resources. The main driving force of mining-land use change also include population, technological progress and policy.

Study on Spatial Variation of Soil Moisture in Coal Mining Subsidence Area in Mu Us Sandy Land

In order to explore the spatial distribution and variation characteristics of soil moisture in coal mining subsidence area in Mu Us sandy Land,and provide theoretical basis for the restoration of the mining area,experiments based on a linear sampling and classic statistical and geostatistical methods were conducted. Spatial distribution characteristics and variation of soil moisture in the typical 0 to 100 cm dune area in the subsidence area and the non-subsidence area( control) were studied. The results showed that in the typical sand dune location of nonsubsidence area( control),the probability distribution curves of soil moisture changes in all layers along vertical and horizontal directions were all normal distribution,and it was consistent with the temporal and spatial variation characteristics of soil moisture in conventional dunes in Mu Us sandy land. By contrast,two years after the coal mine collapsed,the variations of soil moisture in different layers along vertical and horizontal directions were different,and soil moisture loss was more serious than that of control dune by nearly 10% to 30%,and the standard deviation varied from 0. 54 to 1. 05,increasing by 52. 08% compared with the non-subsidence area( control). The probability of positive and negative deviation greater than 1 was over 50%,and the coefficient of variation varied from 0. 14 to 0. 28,which was 80% higher than that of nonsubsidence area( control). After collapsing,the average level of soil moisture,standard deviation,variance and variation coefficient had greatly changed,and influence of coal mining subsidence on soil moisture was the most in the middle layer( 30-70 cm),and was not obvious in the surface( 0-20 cm) and lower layer( 80-100 cm). In coal mining subsidence area,the dispersion degree of soil moisture in different layers along the vertical and horizontal direction was greatly improved,which increased spatial variation of soil moisture.

Progress in Researches on Evaluation of Quality of Cultivated Land Consolidated from Coal Mining Subsided Land

The evaluation of consolidated cultivated land quality can provide basic information for how to perfect the program of land consolidation,as well as a reference for the dynamic monitoring of farmland quality in mining area. Based on the consultation and analysis of related literature,we can conclude that: firstly,most scholars focus on soil consolidation,while consider little about land use and economic condition. Secondly,foreign scholars usually use crop yields to judge the success of land consolidation,while domestic scholars have been evaluated the quality of consolidated cultivated land synthetically from several aspects,such as soil fertility,soil environmental quality,and farmland infrastructure conditions. Specifically,most of the evaluations are static,and indicators are different. Besides,the quality of consolidated cultivated land is generally low,and it lacks systematic research on technologies for improving quality of cultivated land consolidated from coal mining subsided land. It is concluded that future researches should focus on establishing scientific and feasible evaluation system to realize comparison of quality change in the dynamic course of " undisturbed-subsided-consolidated" cultivated land in coal mining areas,as well as technologies for improving quality of cultivated land consolidated from coal mining subsided land.

自燃煤矸石山的遥感识别——基于Landsat 8热红外波段地表温度反演数据

自燃煤矸石山的准确识别和温度影响范围圈定是矿区安全生产、生态修复的关键,煤矸石山自燃过程中表现出的地表温度异常成为其最明显的特征。如何在较大区域尺度快速识别自燃和潜在自燃的煤矸石山,对于自燃煤矸石山治理与防患工作有效开展至关重要。以Landsat 8 TIRS为数据源,利用大气校正法反演获取山西省阳泉市2018年冬季和2019年夏季两天的地表温度,同时利用监督分类法获得的高精度土地利用类型图去除了水体、植被和建筑用地。对得到的包含裸地、煤矸石山的地表温度区域使用阈值分析法,获得了2018年冬季地温异常区域温度范围为11.75~22.12℃,2019年夏季地温异常区域温度范围为32.41~43.31℃。利用已知的42座自燃矸石山进行验证,结果表明:2018年冬季和2019年夏季分别能够识别出的自燃煤矸石山有32座和27座,精度达到了76.19%和64.28%。基于上述提取结果对自燃煤矸石山的影响边界和范围进行了划定,结果表明:自燃煤矸石山的高温影响范围超过500 m。研究结果可为矿区自燃煤矸石山识别提供参考。

Sediment settlement rate and consolidation time of flling reclamation in coal mining subsidence land

With the continuous growth of the population and the continuous reduction of cultivated land,China’s food security is greatly threatened.In addition,China’s coal mining has been mainly underground mining,causing land subsidence and damaging existing cultivated land.This efect intensifes the contradiction between the growth of the risk population and the reduction of cultivated land.The reclamation of mining subsidence land with Yellow River sediment is often used as an efective way to improve the recovery rate of cultivated land.Shortening the reclamation time and realizing continuous flling are signifcant issues.The work presented in this paper studied the sediment settlement rate and consolidation time by combining theory,feld flling and reclamation tests and numerical simulations.A feld flling test study was carried out in the lowlands of Jibeiwang Village,Qihe County,Shandong Province,China.By calculating the drainage consolidation time,the consolidation factor of 0.015656 m^(2)/d,and the time factor for sediment consolidation of 0.575 were determined.The sediment consolidation time for this test was 9.18 days.The calculation of sediment deposition rate and consolidation time is of great practical signifcance to guide the Yellow River sediment flling,realize continuous flling,and save reclamation time and cost.

Study on land use changes of the coal mining area based on TM image

Based on the two temporal TM images of 1995 and 2001 of one coal mining area,analyzed the variety information of the coal mining area.Relative registration were done with the two images firstly,then cut out the study area for experimental data,classi- fied the coal mining area using supervised classification in ERDAS,the coal mining area will be divided into five categories as water body,agricultural land,construction land,coal mining area and other land.Make land use change matrix,the result shows that in the six years of 1995 to 2001,the change of the utilize of the land is greatly,the main represent is showed as follows: the area of water body,agricultural land and coal mining land had con- tinually increased,on the contrary,construction area and other decreased.The percen- tage speed of the construction land is the biggest,the value reach-1.08%.The main rea- sons is that with the exploitation of the coal mine and the reclaim of the land,the exploita- tion of the coal mining land make the agricultural land and construction area convert into coal mining land,on the other hand with the backfill of the subsided waterlogged land and the reclaim of the subsided land make the coal mining land convert into agricultural land.