Drivers of delta subsidence

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Esther Stouthamer, Sanneke Van Asselen

Tuesday 30 june 2015

8:30 - 8:50h at Asia (level 0)

Themes: (T) Special session, (ST) Deltas from multiple pressures to integrated solutions

Parallel session: 4C. Special session: Deltas - from multiple pressures to integrated solutions

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The world’s fertile delta regions, that are supporting large human populations, are subject to significant and irreversible changes due to massive urbanization, climate and land-use change, and land subsidence increasing the risk of flooding. Delta subsidence causes a range of problems, including flooding, fresh water and new land scarcity, salt water intrusion, damage to buildings and infrastructure, loss of cultivated land, wetlands and biodiversity, degradation of fishing areas, and rapid shoreline retreat. Combined with future sea level rise, submerging of deltaic areas is projected to increase by 50% by the end of this century. Addressing the challenge of land subsidence deltas world-wide face requires a sound knowledge of the subsidence drivers. A distinction can be made between natural and human-induced drivers. Natural drivers are: basin and local tectonics, isostasy and sediment compaction due to loading by e.g. sediment. Human-induced drivers are: extraction of hydrocarbons and groundwater, drainage and loading by for example buildings and roads. Natural subsidence rates are in general relatively low compared to human-induced subsidence rates that are relatively high. To influence and reduce especially human-induced subsidence rates it is essential to quantify the relative contribution of the single drivers to total subsidence. This enables the development of sustainable and resilient management strategies to reduce subsidence rates and its negative impacts, thereby improving the livability in future deltas. The aim of our presentation is to give an overview of the natural and human-induced drivers of subsidence and possibilities to reduce subsidence rates and hence its negative impacts.