Analysis of Land Use Characteristics in Mountainous Areas in Yunnan Province Based on Second National Land Survey

Abstract Based on Second National Land Survey during 2007-2009 and land use type survey in ftatland areas, status quo of land use in mountainous areas in Yun- nan was measured, and analysis was made on land use in mountainous areas in terms of land use structure, degree and development potential, providing references for rational use of land in mountainous areas in Yunnan.

Analysis on the Variation of Cultivated Land and Direct Influencing Factors During 1996 to 2006 in Zhejiang Province——Based on Land Survey Results

[Objective] The paper aimed at exploring the variation of cultivated land and influencing factors during 1996 to 2006 in Zhejiang Province more directly,comprehensively and accurately.[Method] The variation of the amount of cultivated land in Zhejiang Province and direct influencing factors had been analyzed using the land survey results of last 10 years.[Result] The cultivated land area of the whole province was reduced by 208 thousand hm2 with a decrease amplitude of 9.8%;terrain slope had played a direct role among the natural influencing factors of cultivated land variation,the cultivated land areas of flats and abrupt slopes were reduced more rapidly,while the terrace areas of gentle slopes had increased;among the social driving forces,the agricultural structure adjustment,construction land expansion and implementation of ecological restoration policy had directly led to the decline of cultivated land areas,while the strict cultivated land protection policy had slowed down the loss of cultivated land.[Conclusion] In conclusion,the declining trend of cultivated land areas is inevitable,so that more scientific general planning of land utilization and more strict land policy has to be utilized more fully in order to guarantee the social and economic development and protect the cultivated land.

Is the Farmland of China Sufficient?——Analysis Based on the Second National Land Survey

According to the data of the second national land survey,the farmland area of China at the end of 2009 was 200 million mu more than the original statistical data.This raises widespread concern.Analysis is carried out from the perspective of task,technique,necessities and effect on China's grain security of the second national land survey.Through analysis,it can be deemed that data of the second national land survey are reliable.It overcomes defects of traditional survey projects and will be of profound significance for grasping current situations of farmland resources in China.Farmers are grain production entities,while the grain yield survey of farmers is calculated through sampling survey of per unit area yield and the sown area.Therefore,the increase in farmland area may indicate underestimation of the grain yield,and the grain security risk of China will decline accordingly.

LM-2D Successfully Launched Land Survey Satellites

LM-2D carrier rockets placed two land survey satellites into their preset orbits from the Jiuquan Satellite Launch Center at 12：11 Beijing time on December 3 and 12：14 Beijing time on December 23 respectively.The missions were the 257th and the 259th flights of the LM series launch vehicle respectively.The two land survey satellites were developed by DFH Satellite Co.,Ltd.under the China Academy of Space Technology（CAST）.

Relationship between spatio-temporal evolution of soil pH and geological environment/surface cover in the eastern Nenjiang River Basin of Northeast China during the past 30 years

To illuminate the spatio-temporal variation characteristics and geochemical driving mechanism of soil pH in the Nenjiang River Basin,the National Multi-objective Regional Geochemical Survey data of topsoil,the Second National Soil Survey data and Normalized Difference Vegetation Index(NDVI)were analyzed.The areas of neutral and alkaline soil decreased by 21100 km^(2)and 30500 km^(2),respectively,while that of strongly alkaline,extremely alkaline,and strongly acidic soil increased by 19600 km^(2),18200 km^(2),and 15500 km^(2),respectively,during the past 30 years.NDVI decreased with the increase of soil pH when soil pH>8.0,and it was reversed when soil pH<5.0.There were significant differences in soil pH with various surface cover types,which showed an ascending order:Arbor<reed<maize<rice<high and medium-covered meadow<low-covered meadow<Puccinellia.The weathering products of minerals rich in K_(2)O,Na_(2)O,CaO,and MgO entered into the low plain and were enriched in different parts by water transportation and lake deposition,while Fe and Al remained in the low hilly areas,which was the geochemical driving mechanism.The results of this study will provide scientific basis for making scientific and rational decisions on soil acidification and salinization.

Optimal decision-making model of spatial sampling for survey of China's land with remotely sensed data

In the remote sensing survey of the country land, cost and accuracy are a pair of conflicts, for which spatial sampling is a preferable solution with the aim of an optimal balance between economic input and accuracy of results, or in other words, acquirement of higher ac-curacy at less cost. Counter to drawbacks of previous application models, e.g. lack of compre-hensive and quantitative-comparison, the optimal decision-making model of spatial sampling is proposed. This model first acquires the possible accuracy-cost diagrams of multiple schemes through initial spatial exploration, then regresses them and standardizes them into a unified ref-erence frame, and finally produces the relatively optimal sampling scheme by using the discrete decision-making function (built by this paper) and comparing them in combination with the dia-grams. According to the test result in the survey of the arable land using remotely sensed data, the Sandwich model, while applied in the survey of the thin-feature and cultivated land areas with aerial photos, can better realize the goal of the best balance between investment and accuracy. With this case and other cases, it is shown that the optimal decision-making model of spatial sampling is a good choice in the survey of the farm areas using remote sensing, with its distin-guished benefit of higher precision at less cost or vice versa. In order to extensively apply the model in the surveys of natural resources, including arable farm areas, this paper proposes the prototype of development using the component technology, that could considerably improve the analysis efficiency by insetting program components within the software environment of GIS and RS.

Using 3-D magnetic modeling to evaluate subsurface structures of the Siwa Oasis,Western Desert,Egypt

This work was designed to study the subsurface structures in the Siwa Oasis area of the Western Desert in Egypt and to determine their effects on surface geologic structures. A detailed land magnetic survey was performed in traverses covering about 400 km2 of the study area. The measured total magnetic field was corrected and reduced to the north magnetic pole. The reduction-to-pole aeromagnetic and Bouguer anomaly maps were used to obtain regional extensions of these subsurface structures, study the continuation of these structures in sedimentary rocks, and delineate the depths to the basement rocks. Data analysis was performed using trend analysis, Euler deconvolution, Werner deconvolution, the Hilbert transform of the analytical signal, and 3-dimensional magnetic modeling methods. The results indicate that the area is affected by tectonic forces in the E-W, N45°-65°E, and N35°-45°W trends, which are correlated with the directions of surface geologic lineaments. The depth to the basement rocks increases from 3.2 km in the southern part to about 3.6 km in the northern part of the area. The results are in good agreement with depths obtained from drill hole data in the area.