Seawater Intrusion: Introduction, Causes, Measures & Research Scope
Introduction:
India is having about 7516 km long coastline
around the borders. Besides considering the population of India
around 25% of the population lives nearby the coastline. Moreover, coastal
zones are having most of the industries over it. India has a wider eastern
coast compared to the western coast which is more saline due to the presence of the Arabian
sea[1].
The availability of saline water within the
nearby range of habitat elevates the problem of seawater intrusion. The eastern
coastal zone is having to sever the problem of intrusion where considering states
Gujarat and some parts of Maharashtra are having very low intrusion problems.
The amount and the reasons related to the seawater intrusion can only be found
by the filed based research studies[2-10].
In simple words, violation of saline water
into the fresh groundwater aquifer is considered as a seawater intrusion[11].
In the normal scenario, seawater is obstructed from entering into an aquifer due
to the movement of the fresh groundwater towards the lower level of groundwater from
the higher one[12].
Causes:
The problem of saltwater invasion is observed
in the coastal aquifers due to several reasons[14]. They may be explained as
decrements in recharge, over exploitation, and contamination due to man-made and
or natural sources[15]. Also, excessive pumping of freshwater is
one of the reasons for seawater intrusion. The intrusion is having the highest possibilities
in the aquifer due to the contamination of cross-aquifer[2]. In the natural
condition, it occurs due to the interaction between the fresh groundwater of low
density with the saline water of high density. The relation of freshwater to
saline water presented by the Ghyben-Herzberg, which represents that only a
half meter of depression in the freshwater can rise the interface of the freshwater - saline water up to 20 metres[11]. The increase in sea level also a
threat to the seawater intrusion as it renders the water interface in the
wells alongside the coastal zone as well as rivers[13]. Constructing a drainage
canal which leads towards the water level decrements[12].
Image Source: Wikipedia
The above image clearly describes the impact of
the seawater intrusion on the habitat. As it is visible from the image from the
left side the reduction of natural habitat can be observed. On the right side
of the image it is evident that due to seawater intrusion reduction of freshwater,
plant growth, and sediment observed. In contrast, an increase in subsidence and
habitat of saltwater observed due to intrusion.
Factors: [2]
There are several factors which affect the
seawater intrusion and are listed below:
- Type, geometry, and geology of the aquifer.
- Variations in the groundwater recharge rates considering annual data.
- Evapotranspiration rates.
- Tidal fluctuations and sea-level changes.
- A time period of lowering the water level in the aquifer.
- Presence of the saline water source in the vicinity of the drainage canal.
- Presence of the salinity control equipment in the drainage canals.
- The rate of groundwater recharge compared with the rate of the extraction.
- Frequencies and the intensity of the rainfall in the region.
- Practices of the agricultural zones and irrigation in the region.
Basic prevention methods: [2]
- By maintain the high water level in the basin.
- By constructing the ridge of the freshwater nearby sea.
- By application of the artificial subsurface barrier along with barrier trough for withdrawal.
- By having appropriate plans for the aquifer improvement.
- By adopting artificial groundwater recharge and rainwater harvesting.
Research scope:
The name or the topic seawater intrusion may be
looks limited in terms of having a appropriate conclusion over its effects,
causes or the measures of prevention but still it is a important topic to
discuss on. There are several ways in which an individual or a group can have
their research over the intrusion topic. The topics for the research may be as follow;
- Modeling of salt water intrusion.
- Analytical or mathematical simulation of seawater intrusion in a coastal aquifer
- Identifying groundwater potential and salt water intrusion.
- Analysis of seawater intrusion considering the sea level rise as a factor.
- Application of measure for saline water intrusion.
- Impacts of climate change on the salt water intrusion for an aquifer.
- Ground water management and the solution of the intrusion in the coastal zones.
In terms of achieving the identifying and having
analysis of saline water there are steps you have to follow several steps. The measurement
of the ground water physical parameters like pH level, electric conductivity,
TDS count, temperature and salinity is the first step after selection of the
region. Thereafter comes analysis of coastal inundation and the study for the
land-use or land-cover. Considering the mapping of salinity geophysical method
is the widely used and accepted[16]. There are several models for the simulation
and modelling listed as follow;
- 3DFEMFAT
- FEFLOW
- HST3D
- AQUA3D
- FEMWATER
- SEAWAT
- MOCDENS3D
References:
[3] Ayolabi EA, Folorunso AF, Odukoya AM, Adeniran AE (2013) Mapping saline
water intrusion into the coastal aquifer with geophysical and geochemical
techniques: The University of Lagos campus case (Nigeria). Springer Plus
2(433): 1-14.
[4] Banks HO, Richter RC (1953) Sea-Water Intrusion into Ground-Water
Basins Bordering The California Coast and Inland Bays, Am. Geophys. Un Trans
34(4): 575-582.
[5] Bruington AE (1969) Control of Sea-Water Intrusion in a Ground-
Water Aquifer, Ground Water 7(3): 9-14.
[6] Barlow M (2003) Freshwater-Saline Water Environments of the Atlantic
Coast, US Geological Survey Report, USGS, USA.
[7] Chachadi AG (2005) Seawater Intrusion Mapping Using Modified GALDIT
Indicator Model: A Case Study in Goa, Jalvigyan Sameksha 20: 29-45.
[8] Chatterjee M, Roy D, Das S, Mazumdar A (2014) Assessment of Water
Resources under Climate Change: Damodar River Basin, India. ARPN J Eng Appl Sci
9(11): 2183-2191.
[9] Das S, Roy D, Mazumdar A, Chowdhury S, Majumder M (2012)
Hydrological feasibility of a mini hydropower plant on Tiljuga River, Bihar,
India. Water Energy Int 69(12): 30-37.
[10] Das S, Nayek M, Das S, Dutta P, Mazumdar A (2014) Impact on Water
Quality in Piyali River, Sundarbans, India due to Saline Water Intrusion.
Indian J Environ Protection 34(12): 1010-1019.
Comments
Post a Comment