Sustainability 2022, 14, 14240. https://doi.org/10.3390/su142114240 www.mdpi.com/journal/sustainability Article A Low-Cost Web Application System for Monitoring Geometrical Impacts of Surface Subsidence Nixon N. Nduji 1, *, Christian N. Madu 1,2 and Chukwuebuka C. Okafor 1 1 Centre for Environmental Management and Control (CEMAC), University of Nigeria (UNN), P.O. Box 410001, Enugu, Nigeria 2 Department of Management and Management Science, Lubin School of Business, Pace University, 1 Pace Plaza, New York, NY 10038, USA * Correspondence: nwannebuike.nduji.pg03550@unn.edu.ng; Tel.: +234-080-6424-4131 Abstract: This paper develops a low-cost web application system for monitoring geometrical im- pacts of surface subsidence. In many of the developing countries, the method of extraction of min- erals such as coal is often impractical and uneconomical, especially with surface mining. With global warming, rapid population growth, and fast-growing urbanization with a disregard for sustaina- bility, the overall subsidence risk has significantly increased. Despite the maturity of Differential Interferometric Synthetic Aperture Radar (DInSAR) for timely monitoring of subsidence hazards, the potential of SAR constellations has been under-exploited, as most applications focus mainly on mapping unstable areas. The developed web application system exploits Sentinel-1 SAR constella- tion and Small-BAseline Subset (SBAS-DInSAR) technique, to provide new streamlines of infor- mation for monitoring solutions and improve disaster risk decision making. We illustrate the model by investigating and measuring potential surface subsidence caused by underground hard coal min- ing activities and exponential urban population growth within a major coalmine in Nigeria. Results of the yearly cumulative amount of horizontal and vertical deformation between 2016 and 2020 range from −25.487 mm to −50.945 mm and −24.532 mm to −57.161 mm, for high and low risks, respectively. Under the influence of external factors such as rising poverty and fast-growing urban- ization, the destruction of in situ stress distributions will likely increase nonlinear deformations. Keywords: urban sustainability; surface subsidence monitoring; disaster risk management; differential interferometric synthetic aperture radar 1. Introduction Geometrical deformation occurs within the Earth rocks when they are continually being subjected to forces that tend to bend, twist, or fracture them [1,2]. When rocks bend, twist, or fracture, they become deformed. This change in shape or size due to subsurface movement of earth materials leads to surface subsidence [2,3]. Deformation of rock mass due to subsidence may be either elastic, plastic, brittle, or any combination of these pro- cesses [1]. This time dependent process usually causes a displacement of surface points or objects in a horizontal or vertical direction [3]. The worldwide need for energy resources required increased production of coal and other fossil fuels [3,4]. A large amount of this production will eventually come from underground mining in areas where surface min- ing is impractical or uneconomical [5]. Most of the major subsidence areas around the world have developed in the past half-century at accelerated rates due to the rapidly in- creasing exploitation of ground water, coal, oil, and gas [3]. The severe impacts created by these subsidence hazards are mostly life threatening in terms of damages to surface utilities and structures, changes in surface and underground water conditions, and envi- ronmental degradation [1,3]. Citation: Nduji, N.N.; Madu, C.N.; Okafor, C.C. A Low-Cost Web Application System for Monitoring Geometrical Impacts of Surface Subsidence. Sustainability 2022, 14, 14240. https://doi.org/10.3390/ su142114240 Academic Editor: Gianluca Mazzucco Received: 13 September 2022 Accepted: 22 October 2022 Published: 31 October 2022 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional claims in published maps and institu- tional affiliations. Copyright: © 2022 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https://cre- ativecommons.org/licenses/by/4.0/).