Identification and adaptation of mitigation measures to counteract intensive land subsidence in a tropical delta system - the example of Camau-Peninsula, Southern Vietnam

        Surface water sampling in Ong Doc river           Questionnaires                                                        Investigate information from household

Exploding of groundwater extraction is one of the main reasons leading to intensive land subsidence in Ca mau. These enormous groundwater extractions from deeper confined aquifers reduce the hydrostatic pressures, resulting in compaction and finally in severe land subsidence of up to 3 cm annually (Erban et al. 2014).
My PhD research aims to develop a methodology to identify regions in Ca Mau province, where the substitution of groundwater with alternative water resources is most promising regarding the availability of these alternative water resources and the societal acceptance.
First of all, it is necessary to find the most serious subsidising areas where the extraction of ground water has to be stopped first. Available alternative water resources are surface waters of local channels and rivers, coastal water, Mekong water or rainwater. Therefore, for each water source, different approaches are needed to fulfil the ultimate goal of identifying alternative water sources, which are suitable in the case of Ca Mau region. It has to be investigated which alternative water resource, whether rain water that must be harvested and stored, local surface water that has to be treated intensively, ocean water that would have to be desalinated or Mekong water that has to be transported and treated, or a mix of those will be the most successful and sustainable solution. Furthermore, the societal acceptance of such a change will be a key issue to establish an alternative water supply, questionnaires shall be carried out to identify the spatial distribution of specific needs for water supply and the acceptances for alternative water resources. The societal commitment to overcome groundwater use is essential for safeguarding Ca Mau Peninsula. This commitment might be different according to land use and economical structure of the different regions in Ca Mau Peninsula.
Both information about water availability and societal preconditions have to be considered in the process to select the best and most promising first pilot area to start to shift the water resource.