Point-line-area-volume index system of land subsidence and application in Ningbo, China

Abstract

Traditional land subsidence indices primarily describe the characteristics of land subsidence at a given site, but such indicators cannot satisfy the requirements for effective land management. We propose a new index system called the point-line-area-volume (PLAV) index system, designed to facilitate efficient description of the geometric characteristics of land subsidence. The system features four indices: the (1) point index system, which describes land subsidence at a site; (2) line index system, which depicts heterogeneous land subsidence between two sites; (3) area index system, which is an indicator of surface land subsidence; and (4) volume index system (VIS), which elucidates land subsidence in terms of soil volume loss. The analytic hierarchy process (AHP) indicates that VIS is the best index system among the four. Additionally, we introduce comprehensive index I, which describes the overall characteristics of land subsidence. The weights of the PLAV indices are calculated by the AHP method. The index system is used to determine the land subsidence characteristics of Ningbo, Zhejiang Province, China and to evaluate the potential hazards for the study site.