Saline Water Freshwater Aquifers Water Dissolved Salts Water Permeable Rock Groundwater Water Well [PDF]

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Salt – Water Intrusion Saltwater intrusion is the movement of saline water into freshwater aquifers. Saline water is water that contains a significant concentration of dissolved salts and an aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials from which groundwater can be extracted using a water well. When the fresh groundwater supply decreases the boundary can move further inland. Conversely, when the fresh groundwater supply increases, the boundary can shift seaward. When the mixing of saltwater with freshwater beneath the surface occurs in an area that was previously fresh. Saltwater intrusion can become a problem when saltwater moves far enough inland that it “intrudes” into fresh groundwater sources, which can lead to contamination of drinking water sources and other consequences. Saltwater intrusion is a problem because it contaminates the fresh water. The consequences of saltwater intrusion for supply wells vary widely, depending on extent of the intrusion, the intended use of the water, and whether the salinity exceeds standards for the intended use. It is important to note that saltwater composed most of the body of water. Saltwater is about 97.5% of the whole body of water. The remaining 2.5% is the fresh water, which is considerably insignificant amount of water but is very important to all living being in this planet. Plants, animals, and we human beings need to drink from fresh water. Let us try to imagine if this problem of saltwater intrusion continues to occur, there will come a time that many of us have the difficulty to find a fresh water to drink. This problem mostly happens in coastal areas, because sea level rise, changing precipitation regimes and changing groundwater recharge rates may influence the incidence of saltwater intrusion. While some elements are likely to have more direct impacts on saltwater intrusion (e.g., sea-level rise), others may have an impact in less direct ways (e.g., changing recharge regimes), depending on local conditions. In all cases, however, the dynamic subsurface interaction between freshwater and saltwater is both complex and influential, and is therefore deserving of close attention in coastal regions. We know for a fact that Philippines is an archipelago, which some of its islands are considered coastal. Thus, this country is really affected by this saltwater intrusion. This is a big problem that needs attention and solution. Though saltwater intrusion is a naturally occurring process, it can also be influenced by human activity. One of the causes is the groundwater extraction. Groundwater extraction can lower the level of the freshwater table, reducing the pressure exerted by the freshwater column and allowing the denser saltwater to move inland laterally. When coastal communities use wells to pump fresh drinking water to the surface, it often makes the problem of saltwater intrusion worse. When more freshwater is pumped from the ground than groundwater can supply, as can often occur in densely-populated coastal areas, the well starts to pump water with

an increased salt content. Once groundwater is contaminated with too much saltwater, the well or groundwater source can no longer be used for drinking water, and it often has to be abandoned altogether. Another cause of saltwater intrusion is the construction of canals and drainage networks. Drainage networks constructed to drain flat coastal areas can lead to intrusion by lowering the freshwater table, reducing the water pressure exerted by the freshwater column. Other contributors to saltwater intrusion include navigation channels or agricultural and drainage channels, which provide conduits for saltwater to move inland, and sea level rise. Saltwater intrusion can also be worsened by extreme events like storm surges, like what happened in Tacloban. Saltwater intrusion, as stated above, is a naturally occurring process. However, it can be prevented from worsening by reducing or stopping the man made contributions of this issue, such as ground water extraction, the not very planned canals and drainage networks, and the not so well-organized agricultural drainages. There should be an agency or department of the government that would settle this matter. Perhaps, the Department of Environment and Natural Resources (DENR) must work on the preservation of our fresh water. Lastly, we, as the guardian of our environment, may plant more trees, segregate and dispose our garbage properly, and conserve water by doing simple things such as, but not limited to, turning off our faucet properly if not in use, turn on our faucet in a moderate manner, store water, and water our plants using our stored water.

Sources: https://en.wikipedia.org/wiki/Saltwater_intrusion https://en.wikipedia.org/wiki/Saline_water https://en.wikipedia.org/wiki/Aquifer http://pubs.usgs.gov/circ/2003/circ1262/#heading156057192 https://en.wikipedia.org/wiki/Saltwater_intrusion#Causes https://en.wikipedia.org/wiki/Saltwater_intrusion#Effect_on_water_supply http://www.gov.pe.ca/photos/original/cle_WA1.pdf