Land subsidence due to groundwater pumping: hazard
probability assessment through the combination
of Bayesian model and fuzzy set theory
H. Li, L. Zhu, X. Li
Capital Normal University, Beijing, China
G. Guo, R. Wang
Beijing Institute of Hydrogeology and Engineering Geology, Beijing, China
Y. Zhang
Key Laboratory of Earth Fissures Geological Disaster, Ministry of Natural Resources,
Geological Survey of Jiangsu Province, Jiangsu, China
Z. Dai
College of Construction Engineering, Jilin University, Changchun, China
L. Chang
Fourth Institute of Hydrogeology and Engineering Geology, Hebei Bureau of Geology and
Mineral Resources Exploration, Hebei, China
P. Teatini
Dept. of Civil, Environmental and Architectural Engineering,
University of Padova, Padova, Italy
Land subsidence caused by groundwater overpumping threatens the sustainable development in Beijing.
Hazard assessments of land subsidence can provide early
warning information to improve prevention measures. However, uncertainty and fuzziness are
the major issues during hazard assessments of land subsidence. We propose
a method that integrates fuzzy set theory and weighted
Bayesian model (FWBM) to evaluate the hazard probability of land subsidence measured by
Interferometric Synthetic
Aperture Radar (InSAR) technology. The model is structured
as a directed acyclic graph. The hazard probability distribution of each factor
triggering land subsidence is determined
using Bayes' theorem. Fuzzification of the factor significance
reduces the ambiguity of the relationship between the factors
and subsidence. The probability of land subsidence hazard
under multiple factors is then calculated with the FWBM.
The subsidence time series obtained by InSAR is used to
infer the updated posterior probability. The upper and middle parts of the Chaobai River
alluvial fan are taken as a case-study site, which locates the first large-scale emergency
groundwater resource region in the Beijing plain. The results show that rates of groundwater
level decrease more than 1 m yr-1 in the confined and unconfined aquifers, with
cumulative thicknesses of the compressible sediments between 160 and 170 m and Quaternary
thicknesses between 400 and 500 m, yielding maximum hazard probabilities of 0.65, 0.68,
0.32, and 0.35, respectively. The overall hazard probability of
land subsidence in the study area decreased from 51.3% to
28.3% between 2003 and 2017 due to lower rates of groundwater level decrease. This study
provides useful insights for decision makers to select different approaches for land
subsidence prevention.
