Subsidence and Deforestation: Implications for Flooding in Delta’s Southeast and East Asia

Abstract

Delta is a low-lying area which can be found at the mouth of a river. Nowadays, concentration of flooding occurs in many deltaic areas due to combination of several factors. Meanwhile, a big number of people live on flood plain of main rivers and river deltas which will be threatened by flooding. Land subsidence and deforestation are two phenomena which had been occurring very high until recently in SEE Asia region. Increasing of population strongly influences the natural hydrological processes. Due to pressure for land, substantial areas of peat swamps in SEE Asia have been presently are being reclaimed for agriculture or for other land use. In natural conditions swamp areas functioned as a retention area by adsorbing flood water, thereby preventing or mitigation flooding in downstream areas. But unfortunately, large areas of the original forests in large peat swamp forests have disappeared due to human activities such as illegal logging and fires. In other side increasing population, industries, agricultures and plantations will increase water demand. Activities of ground water extraction will be increasing as well. It can cause land subsidence and furthermore tide can easily propagate into deltaic areas moreover compounded by lowering of land surface due to land subsidence. Since flooding is an issue has been identified then these two phenomena need to be identified as well.