Urban Construction Land Suitability Evaluation Based on Improved Multi-criteria Evaluation Based on GIS(MCE-GIS): Case of New Hefei City,China

Urban construction land suitability evaluation （UCLSE） is a complex system engineering and the basis for rational use of the limited urban land resources in China. It has an important practical value on urban construction land use planning and management from the angle of methodology. As a widely used technique, traditional multi-criteria evaluation based on GIS （MCE-GIS）, is not suitable for UCLSE. This study develops an improved MCE-GIS method which could be more suitable for UCLSE based on urban complex ecological system theory and the summary of the shortcomings of traditional MCE-GIS. The improvements include three aspects： a composite evaluation index system rather than natural indexes alone, an index weight calculated by using fuzzy Analytic Hierarchy Process （AHP） method rather than the common AHP method, and the integrated overlay rule, which includes selecting the minimum value, weighted linear combination （WLC） and simple summation. The main advantage of this improved technique is that it can make UCLSE more comprehensive, more operational and more reasonable. It can provide a scientific basis for decision making in the planning and management of urban construction land use. The improved MCE-GIS system has been adopted in the New Hefei City, Anhui Province, China. Based on the results of UCLSE in New Hefei, three functional areas including construction-appropriate areas, construction-restricted areas and construction-forbidden areas could be worked out, in which 36.90% of the total study area could be developed as urban construction land and the remaining 63.10% should be protected as reserves land or as ecological land. Furthermore, the results can orovide scientific decision suooort for spatial planning and eco-environment nrotection in New Hefei.

Evaluation of suitability,adaptability,and reserve potential of construction land on the Qinghai-Tibet Plateau

Construction land is the leading carrier of human activities such as production and living.Evaluating the construction land suitability(CLS)on the Qinghai-Tibet Plateau(QTP)holds significant implications for harmonizing the relationship between ecological protection and human activity and promoting population and industry layout optimization.However,no relevant studies provide a complete CLS assessment of the QTP.In this study,we developed a model-based CLS evaluation framework coupling of pattern and process to calculate the global CLS on the QTP based on a previously developed CLS evaluation model.Then,using the land-use data of 1990,2000,2010,and 2020,we examined the adaptability of existing construction land(ECL)to the CLS assessment result through the adaptability index and vertical gradient index and further analyzed the limitations of maladaptive construction land.Finally,we calculated the potential area of reserve suitable construction land.This article includes four conclusions:(1)The highly suitable,suitable,moderately suitable,marginally suitable,and unsuitable CLS classes cover areas of 0.33×10^(4)km^(2),10.42×10^(4)km^(2),18.06×10^(4)km^(2),24.12×10^(4)km^(2),and 205.29×10^(4)km^(2),respectively.Only approximately 11%of the study area on the QTP is suitable for large-scale permanent construction land,and approximately 79.50%of the area is unsuitable under current economic and technological conditions.(2)The ECL adaptability index is 85.16%,85.93%,85.18%,and 78.01%during 1990–2020,respectively,with an average adaptability index exceeding 80%on the QTP.The ECL distribution generally conforms to construction land suitable space characteristics but with a significant spatial difference.(3)From 1990 to 2020,the maladaptive ECL was dominated by rural settlement land,transport land,and special land,with a rapidly increasing proportion of urban and other construction land.The maladaptive ECL is constrained by both elevation and slope in the southern Qinghai Plateau,the Hengduan Mountains,and the Qilian Mountains.In contrast,elevation is significantly more limiting than slope in the northern Tibet Plateau,the Gangdis Mountains,and the Himalayan Mountains.(4)The potential area of reserve suitable construction land is 12.41×10^(4)km^(2),accounting for 4.81%of the total land area of the QTP,and the per capita area is 9928 m^(2).Regions of Qaidam Basin,Gonghe Basin,and Lhasa-Shannan Valley have the richest and most concentrated land resource of reserve suitable construction land.The research results provide spatial decision support for urban and rural settlement planning and ecological migration on the QTP.

Engineering Geological Study of the Active Tectonic Region for Hydropower Development on the Jinsha River,Upstream of the Yangtze River

The Jinsha River runs across the Hengduanshan north-south tectonic zone where neotectonism was relatively strong, accompanied by various geologic hazards. In this case, it seems necessary to make a quantitative assessment and grading of the engineering geological environment for the planning and development of hydropower projects on the Jinsha River.

Evaluation method and empirical application of human activity suitability of land resources in Qinghai-Tibet Plateau

The current suitability evaluation methods for land resources human activity in China suffer from theoretical deficiencies related to fundamental data accuracy,elevation and slope classification,and suitability class judgment.Empirical application of these methods is also hindered by excessive evaluation indicators,data acquisition difficulties,and limited applicability to high altitude regions.To address these issues,this paper proposes a technical evaluation framework for the Qinghai-Tibet Plateau(QTP) that employs selected key parameters varying with elevation and slope to establish grid-scale evaluation models for construction land suitability(CLS) and arable land suitability(ALS).A generalized algorithm is then proposed for key parameters such as air density,air temperature,slope suitability for construction,and soil erosion resistance of sloping arable land.Empirical research is conducted using Milin County in southeast Tibet as a case study,with interval measurements of 100 m in elevation and 1° in slope.The evaluation model is tested using grid accuracies of 30 m,50 m,100 m,250 m,500 m,and 1000 m.The results reveal that:Firstly,the CLS and ALS can be categorized into five classes:highly suitable,suitable,moderately suitable,marginally suitable,and unsuitable,with varying area ratios under different grid accuracies.Secondly,existing construction lands in Milin County are mainly distributed in suitable,highly suitable,and moderately suitable CLS classes,accounting for over 94% of the total area studied under different grid accuracies.While arable land is mainly distributed in suitable,highly suitable,and moderately suitable ALS classes,accounting for over 96%.Thirdly,the empirical research in Milin County indicates that the evaluation method,quantitative model,and parameters algorithm for evaluating human activity suitability of land resources on the QTP are feasible and applicable,with a recommended grid accuracy within 100 m and a maximum of 250 m.Fourthly,the paper establishes a correspondence between land suitability(including construction land and arable land) and topographic factors(elevation and slope) that can be applied to the QTP.Finally,some professional defects in the evaluation methods of available land resources in Major Function Zoning and “Double Evaluations” of Territorial Spatial Planning in China when applied to the QTP are identified.