| Increased salt water intrusion into deltas is an important effect of climate change and sea level rise. Although the general processes are well understood, the locally specific effects are not. To enable management and adaptation, the present situation and its links to sea level and climatic conditions will be analyzed. The research consists of four parts: " Scenario development and selection for future changes. Less fresh water, be it through climate change or through changes in upstream water use, may be available to suppress salt water seepage. Sea level rise will increase the piezometric level of the lower salt water aquifer. Land surface subsidence will continue as well. The combined effect of reduced fresh water availability, sea level rise, and land subsidence will increase salt water seepage into areas that are, until now, used for agriculture. The question then becomes, what are good scenarios to use to model future changes in fresh water availability? " Monitoring of the present interaction between the salt groundwater and the surface water system in both deltas. This monitoring will use the innovative Distributed Sensing (DTS) technique to detect and quantify seeps at the bottom of canals. " Modelling of groundwater flow, taking salt/fresh water density gradients into account. There are major local differences and preferential flow paths in the sub-surface. At this moment, nobody really knows how much water enters the deltas from below. " Given the increased salt level in the agricultural areas, what management options do we have to make optimal use of available fresh water resources? Presently, extensive flushing the system with fresh water from outside the system is the preferred strategy. Instead, we suggest developing a new method based on control theory, which uses in situ measurements to adjust the flow of fresh water through the system. |
