A geometry-based method for automated sampling point arrangement in 1∶50,000 stream sediment surveys

In current geochemical surveys of stream sediments, manual sampling point arrangement predominates. However, manual arrangement faces several challenges, including heavy workload, high subjectivity, and insufficient control over river basin coverage. Moreover, the lack of effective quality inspection after sampling point arrangement renders it difficult to ensure the rationality of the arrangement. These issues affect field operations and the reliability of subsequent geochemical interpretations. Using the ArcGIS system, this study implemented computer automation-based scientific sampling point arrangement as per the geometric characteristics (e.g., order and length) of streams. Furthermore, a model for the verification of sampling point rationality was developed to assess the rationality of the distribution and sampleability of the automatically arranged sampling points. The proposed method was applied to the sampling point arrangement of stream sediments in the Majiagou area within the 1∶50,000 Sanheba map sheet. The results indicate that the automated arrangement achieved a nearest neighbor index of 1.1. This finding suggests a uniform sampling point distribution, with an absence of unreasonable gaps. Notably, 84.7% of the sampling points were distributed along the first-order streams, with a sampling density of 4.6 points/km². The resulting sampling point layout complies with the requirements in relevant specifications and satisfies the prerequisites for field operations. Therefore, the method of automated sampling point arrangement significantly enhances the efficiency and reasonableness of indoor sampling point arrangement, holding high practical value.