• Introduction
• Causes of land subsidence
• Techniques of measuring land subsidence
• Maps showing land subsidence
• Consequences of land subsidence and overpumping of groundwater
• Background and contacts

Introduction

The city of Bangkok, Thailand has been subjected to land subsidence, in the past as well as nowadays. Land subsidence can be defined as a gentle and continuous lowering of the ground surface. This occurrence is very often experienced in areas with relative soft soil. It is however worth noting that in the Bangkok area this subsidence has reached severe proportions. For example: in some areas a maximum subsidence of about one meter has been observed over the last 23 years (since research started in 1978).

The consequences of such severe land subsidence are clear and can be subdivided into two main categories:

• Damage to and destruction of the infrastructure such as the foundations of buildings, buried pipelines, wastewater sewers, roads and bridges

• Disturbance of the local natural water system, for instance extended and more intense flooding by river- or seawater, intrusion of salt water to the aquifers, disturbance and deterioration of the existing rainwater drainage system.

It is worth noting that land subsidence is a general phenomenon that occurs in many areas of the world. Well-known case studies have been carried out for areas in California, Mexico City, Venice, the Mississippi Delta, Jakarta, Shanghai and the Netherlands.