农村土地承包经营权调查中面积精度问题分析

Area accuracy analysis for investigation of rural land contractual management right

面积精度是农村土地承包经营权调查的主要技术指标之一,为确保农村承包土地调查的面积精度,该文以界址点精度和面积精度的关系为基础,结合测量误差传播理论,从理论上分析了农村承包土地调查面积精度的影响因素,从实践角度分析了不同调查方式界址点精度对面积精度的影响。分析表明:1)地块面积精度主要受界址点精度、地块面积和地块形状(长宽比)的影响;2)仅从满足面积精度的角度考虑,实测法适用于全国所有地区,南方大部分区域可采用不低于1∶1 000的比例尺,北方大部分区域可采用不低于1∶2 000的比例尺;3)采用比例尺为1∶10 000的国土"二调"影像开展承包经营权调查时,平地区域南方和北方的地块面积不应小于1.25和4.56 hm^2,山地区域不应小于2.81和10.25 hm^2。该研究为不同方式调查农村承包土地的面积精度问题提供了理论和实践参考。

Area accuracy is one of the most important technical indices in the investigation of the right of rural land contractual management. This study was designed to quantify the influence factors to area accuracy from theoretical and practical aspects. We first analyzed the factors relating to rural land area survey accuracy based on the measurement error propagation theory. The relationship between the boundary point and area accuracy was evaluated from the theoretical view point. The influence of the following factors on the area was analyzed： the shape of the land parcel, the number of boundary points, the distribution of boundary points and the mean square error of boundary point. Then, the influence of different survey methods, such as the analytic method, the aerial photography method and the graphic method on the area accuracy, was quantitatively assessed at typical south China（Sichuan Province） and north China（Liaoning Province） rural areas with taking into account the terrain type（plain and mountain area）. We also evaluated the influence of 3 different survey methods under different conditions, for example, various shape（the ratio of length to width changed from 1 to 10） or area size（from 0 to 12 hm^2）. Finally, the area lower limit of land parcel by using different methods was calculated and analyzed from a practical view. We did back-calculation works based on the mathematical formula describing the relationship between land parcel area and the land shape, area relative error and mean square error of boundary point. Different area lower limits were presented by considering various land shape and error of boundary point. The imagery of the Second National Land Survey was also analyzed for its applicability in the investigation of the right of rural land contractual management. The results showed that： 1） Theoretically, the relative area accuracy was mainly influenced by the mean square error of boundary point, the area of the land parcel and the shape of the land（ratio of length to width）. The influences of the number and distribution of boundary points on the relative area accuracy were insignificant for the strict setting rules of the boundary points. From the operational view, the appropriate increase of the number of the boundary points would greatly improve the area accuracy in the land survey; 2） Only considering to keep the relative area accuracy within a reasonable range, the analytic（surveying with global position system-real time kinematic, GPS-RTK） method was generally applicable over all regions of the whole country. Imagery with the scale no less than 1：1000 could be applied for most of the southern region with the ratio of length to width being equal to 2, and for most of the northern region with the ratio of length to width equaling 9, the imagery scale should be no less than 1：2000; 3） To carry out the rural land parcel contractual management survey with ＂the Second National Land Survey＂ images with a scale of 1：10000, the land area in plain should not be less than 1.25 and 4.56 hm^2 in north and south China. In mountainous area, the land parcel area should not be less than 2.81 and 10.25 hm^2 respectively. The study provides both theoretical and practical suggestions for the investigation of the land area accuracy of rural contracted land with different methods.