Article Type: Research Article Article Citation: Pinaki Sardar.
(2021). A COMPREHENSIVE GEO –SPATIAL STUDY ON THE IMPACT OF SALINITY:
CHALLENGES TO AGRICULTURAL YIELD IN MATLA –BIDYADHARI INTERFLUVE. International
Journal of Research -GRANTHAALAYAH, 9(1), 112-122. https://doi.org/10.29121/granthaalayah.v9.i1.2021.2980 Received Date: 01 January 2021 Accepted Date: 29 January 2021 Keywords: Remote Sensing and
GIS Salinity Soil pH Irrigation Increasing salinity is a major concern to the tropical coastline agricultural system. To ensure crop production and to satisfy food requirement, land reform system should be revamped in Matla –Bidyadhari interfluvial region, south 24 paraganas West Bengal. This study shows the effectiveness of GIS and Remote Sensing techniques in measuring impact of salinity on agricultural planning. The research work covers 809 sq. km area of Gosaba and Basanti Block, West Bengal. Soil samples were taken from various ground control points of these Blocks. After getting that information, soil clay fraction map, drainage map, land use map, salinity zonation map has been created by using satellite data on Arc GIS 10.6 software. These thematic maps can be use in agricultural planning. To cope with increasing salinity, it is recommended, deep water irrigation in dry season. Vegetables are more sensitive than cereal crops to salinity, so they can be yield in seasonal variation.
1. INTRODUCTIONTo
increase agricultural yielding and to satisfy food requirements land reform
sequences should be revamped in Matla –Bidyadhari Interfluvial region, south 24
paraganas, West Bengal. Though this needs to assess huge quantity of spatial
data, using traditional methods of surveying lands. It is also time consuming.
Numerous land capability assessment techniques are used versions to the local
settings of framework for Land Evaluation (FAO,2007) and centre on the
sternness of land restrictions connected to crops and land use (Desmet, P., et.
al., 2009). Hence the collected informations are included and organized in GIS
to gain various thematic data for using in analysis process. Remote Sensing
techniques are inevitable in assessing the satellite-based data sets and to
realize the changes in land use patterns. As land capability assessment needs
various spatial and non- spatial data (land use, topography, soil salinity
etc.), GIS provides various tools to manipulate datasets into thematic maps.
Now a day, soil salinity is a major concern to farmers. Crops grown in saline
soil are prone to osmotic stress, nutrition disorder and toxicity, which reduce
productivity. Saline stress is a major problem to cope with increasing food
demand. 2.
OBJECTIVES
1) To
indicate the potentiality of Remote Sensing in salinity measurement. 2) To
investigate the spatial planning for agricultural land use settings. 3) To
study how land capability plays a significant role in detecting limits in
sustainable agricultural planning. 3.
STUDY
AREA
3.1. LOCATIONAL EXTENT
The study
area is situated in south 24 paraganas, West Bengal. Basanti Block with 13 GPs
and Gosaba Block with 4GPs have covered the whole region. It extends from 21 0
29 ‘N to 22 0 30’ N and 88 0 29 ‘E to 89 0 E. The area covers 809 sq. km. with
Matla River in the west, Bidyadhari River in the east, Herobhanga Reserve
forest in the south, and Canning – 2 Block in the north. Figure 1: Location
of Study Area 3.2. GEOLOGICAL FORMATION
This area
originated during middle- upper Cretaceous period. Several subsidence and
Gangetic deposition bring the recent changes in this region. The whole deltaic
area has an easterly tilt, which gives the unique direction to drainage
patterns. 3.3. THE INTERFLUVIAL RIVER SYSTEM
Matla and
Bidyadhari are the two main tidal fed rivers with many distributaries, creates
an estuarine river system. Ox – bow lakes, meander channel, mangrove swamp
river bed islands, point bar/ charas are the various geomorphic features here.
However cyclonic storms or high tidal water (7 m) flooded the southern part
with various depths. GLIMPSES OF STUDY
AREA Figure 2: Some
glimpses at a glance. 3.4. SOIL TYPES
Soils of
this area are saline in nature and Azonal Type with little formed profile. Main
soil types are – a) Coarse
Loamy Soil b) Fine
Loamy Soil c) Sandy
Loamy Soil d) Silty
Clay Soil e) Silty
Loamy Soil 3.5. CLIMATIC CONDITION
The
average maximum and minimum temperature are 37 0c and 14 0c. Most of the
rainfall occurs during month of June to September by south – west Monsoonal
wind (400 cm – 500 cm). During March _April and October cyclonic storm develops
on Bay of Bengal. 4.
METHODOLOGY
4.1. REMOTE SENSING DATA COLLECTION AND PROCESSING
After
obtaining satellite data from USGS Earth Explorer, it has to be gone through
Radiometric and Geometric corrections (atmospheric corrections by computing
reflectance, registered to UTM Map Projection). Field work had been done by using
28 ground control points. Using those data NDVI and NDSI was calculated. Data
classification had done by using input training samples and Maximum Likelihood
method. STRM data (90 mts. Resolution) had been utilized to create DEM, Slope,
and Aspect. NDVI = (NIR – RED) / (NIR + RED)
[Where,
NIR = Near Infra-Red, Red =
Visible Red] (Equation -1) NDSI = (Green – SWIR 1) / (Green – SWIR 1)
[Where, Green = Visible Green,
SWIR 1 = Short Wave Infra-Red] (Equation – 2) Table 1: Satellite data characteristics
4.2. COLLECTION OF SOIL DATA
To collect soil
sample 1 meter depth bores were excavated. This was done to determine the
physical and chemical properties of soil. It was tested at Soil and Salinity
Research Center, Canning. Then, these informations are used to create thematic
maps with Spatial Analyst Tools in Arc GIS 10.6. Figure 4: Saline effect on soil. 5.
RESULTS
AND DISCUSSIONS
5.1. Landuse And Landcover
a) Major Landuse types are – 1) Agricultural Land, 2) Fallow Land, b) Major Landcover types are – 1)
Mangrove Forest, 2) Salt Pan, 3) Marshy Land, 4) Water Bodies The area extends
809 sq. km., among which Drainage and Marshy Land covers 183sq. km.(22.63%)
area, Fallow Land covers 163sq. km.(20.15%) area, Salt Land covers
159sq.km.(19.65%) area, Mangrove and Dense Forest covers 192sq.km.(23.73%)
area, and Agricultural Land covers 112sq. km.(13.84%) area. Major cultivating
crop is paddy. Besides this, tomato, beetle leaves, potato etc. are also grown
by farmers. Recently many agricultural lands have converted into aqua cultural
ground (shrimp, prawn fisheries). Figure 5: Land use land cover map of study area. 5.2. Soil Texture
To determine the
surface run off, three major soil hydrological group has been identified, viz.
– A, B, D.
Table 2: Hydrological Group of Soil
The Group A soil
covers 363.61sq. Km, Group B soil covers 48.24sq.km, and the Group D soil
covers 175.2 sq. km. This reveals that Group A soil is predominating with high
infiltration, which causes water logging. Organic manure may apply by Mulching
Process in Sandy soils, as sandy texture features excessive water loss. Loamy
texture is also able to drain excess water but unable to hold nutrients. Figure 6: Physical Properties of Soil in Study
Area. 5.3. Salinity Status
5.3.1. DERIVING SALINITY LEVEL WITH PH Table 3: pH Level of Collected Soil Samples
with Their Location Using GPS
On the basis of
obtained pH values 5 Saline zonation has been created – ·
Very Low (7 to >8) – Baria, Kumirmari, Choto Mullakhali, Bairam
Chowranghee, Simultala etc. ·
Low (6 to 7) – Harankhali, Gosaba, Ramgopalpur, Jharkhali etc. ·
Moderate (5 to 6) – Punjal, Bara Mullakhali, Chandimore, Majherpara etc. ·
High and Very High (4 to 5) – Harabaidya, Jyotiramghat, Gobindapur,
Arampur etc. Figure 7: Salinity Zones at the Study Area (based
on pH Level). 5.3.2. DERIVING SALINITY LEVEL WITH ELECTRICAL
CONDUCTIVITY (DS/M) Table 4: Electrical Conductivity and
Sodium absorption ratio Of GCP Points
To
measure the salinity status electrical conductivity method has been used.
Salinity zonation map was made on the basis of EC using Arc GIS 10.6 software.
Very high EC value concentration was found in Gosaba, Jharkhali, Harankhali,
and Gobindapur. Low and Very Low EC values were in Bairam Chowranghee,
Ramgopalpur, Simultala, and Bara Mullakhali. Various parameters like pH,
Electrical Conductivity, Sodium Absorption Ratio has been obtained according to
Indian Standard (pH <8.5 = Saline Soil, EC > 4 = Saline Soil, SAR < 13 = Saline Soil, SAR > 13 = Alkaline Soil). Figure 8: Salinity
Zones at Study Area (based on Electrical Conductivity) 5.4. Climatic Factors
Fluctuation
in rainfall and rise in temperature are the main causes behind climate change,
which have various impacts on study area. Study reveals that increase in winter
temperature creates higher evaporation rate from river surface. Also decreasing rainfall rate in dry season
would result low flow situation in river. This will increase salinity level in
near future. The study area receives average 475mm annual rainfall. Highest
temperature (420c) recorded in month of May. Generally, June to September considered
as rainy season, these are the main cropping period. But rain water can be
store for dry season (mainly for paddy cultivation). Another important cause is
intrusion of much tidal water in river. In dry season, when amount of rainfall
decreases, the river fresh water recedes, which leads to increase in salinity
level. Figure 9: Simplification of salinity intrusion process. 6.
IMPACT
OF SALINITY IN RIVER WATER
Increasing
salinity in river water leads to crop reduction, decline in industrial
production, and decrease in forest species productivity and increase health
hazards. This is the main cause of converting many agricultural lands into aqua
cultural ground. Report also reveals that saline water has negative effect on
domestic cattle (reduction in milk production and reproductive health). 7.
IMPACT
OF SALINITY ON AGRICULTURAL PRODUCTION
7.1. OSMOTIC EFFECT
Increasing
salinity lowers the level of soil water potentiality and increase salt
concentration at plant root. Thus, plant cannot extract adequate amount of
water from surface. This osmotic effect reduces plant growth. Higher level of
EC reveals that less water availability to plant. Current study shows that 1.84
ds/m EC in irrigation water is moderately saline, according to FAO (1992). Figure 10: Effect of
Salinity on Agricultural Production. 7.2. ION EFFECT
Higher
concentration of Na and Cl may restrain plant growth. It causes burning leaf
tip, reduce membrane function and hampers nutrient intake. This may happen
either while the ions are extracted by the plant root or when get contacts with
leaves. In this area, Cl concentration in irrigation water was measured as
435ppm (source: soil and salinity research centre, Canning), which reveals that
crops are susceptible to ion effect. Figure 11: Burnt
Leaf and Dead Tissues at the edge of leaves 8.
FARMER’S
VIEWPOINT ON SALINITY
Survey
was done among households, sharecroppers, who grow Aman and Boro crops (paddy,
vegetables, pulses, oilseeds, spices). According to them, salinity effects more
in dry season. Productivity has been decreasing for last 7 – 9 years. 10 %
respondents argued that they facing fresh water crisis (drinking and
irrigation), 28 % reported reduction in crop size and early yellowing of
leaves. According to them, vegetables are more sensitive to salinity than
cereals. 9.
CONCLUSION
AND RECOMMENDATIONS
The
salinity level shows an increase trend in soil and surface water in the study
area. Climate change, tidal water intrusion, storm surge – all are accelerating
this salinization process. Higher pH incorporates deficiency of phosphorous,
iron etc. Appropriate fertilizer should be applied to cope with this problem.
Gypsum or Calcium sulphate could be applied to release Ca ion and replace Na
ion. Deep water irrigation can also reduce the salinity some extent. Reduction
in yield will affect the livelihood, income level, and food security of local
people. SOURCES OF FUNDING
This
research received no specific grant from any funding agency in the public,
commercial, or not-for-profit sectors. CONFLICT OF INTEREST
The
author have declared that no competing interests exist. ACKNOWLEDGMENT
The
author expresses his gratitude to all concern officers of Soil and Salinity
Research Center, Canning Town, for helping and providing necessary information.
The author cordially acknowledges USGS for supplying satellite imageries.
Besides, the author also thanks local people for co-operating during field
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