26 nov16 3d_salinity_mapping
TRANSCRIPT
(National Workshop on Challenges In Irrigation Management For Food Security, Roorkee, 26 Nov 2016)
D.S. Bundela*, D.K. Sharma, J. Triantafilis, Bhaskar Narjary and Aslam Pathan
ICAR-Central Soil Salinity Research Institute, Karnal y& UNSW, Sydney, Australia
E-mail: [email protected]
Background
• Canal irrigation development paradigm resulted in several-folds increase in crop productivity during green revolutionfolds increase in crop productivity during green revolution
• It was forgotten that mega quantities of water also introduce mega quantities of salts into an irrigated areaintroduce mega quantities of salts into an irrigated area and change its hydrology and salt balance
• Consequently, irrigated lands has started losing yield gain and over a period of time, these lands develop into twin problems- soil salinity & waterlogging.
• Soil salinity and sodicity are widespread in irrigated areas under arid & semi-arid regions of India as well in the World.
• In India, irrigation water mobilizes salts and aggravates the secondary salinization problem in ~20% of irrigated areas
Background…
• Remote sensing provides spatial distribution of soil surface salinity that too moderate and severe classes but not slightsalinity that too moderate and severe classes, but not slight class of surface salinity and NOT at all sub surface salinity
P i l i b d h i l th d id• Proximal sensing based geophysical methods provide spatial & vertical distribution of salts in soil profiles/regolith
f• Therefore, there is need to apply multiple coil DUALEM technology in salinity research to collect EM data quickly for 3D salinity assessment and mappingy pp g
• Expansion of secondary salinization in canal commands
• 50,000 ha under waterlogged saline soils in Haryana
• 2.95 m ha saline soils in the country
Huge Potential: Proximal sensing for rapid assessment of soil salinity
Single coil (EM38) multiple coils (DUALEM)
Objectives
• To assess and map soil salinity at two Indian sites togenerate reliable 2D /3D EM conductivity/ soil salinityimages for salinity managementimages for salinity management
• To monitor the efficacy and impact of salinitymanagement strategies implemented by re measuringmanagement strategies implemented by re-measuringand remapping salinity
Study Area: Western Yamuna CanalStudy Area: Western Yamuna Canal CommandCommand
WYC
GCA: 13,543 sq kmCCA 10 840 kCCA: 10,840 sq km
7 Water CirclesDistricts: 5 Full
7 PartTehsils: 14 Full
22 Part
Nain Field
Mokha Kheri
Villages: 2206
Mokha Kheri
Technology shift from EM38 to DUALEM System
Conventional: Geonics EM-38
DUALEM‐21, 421 and 642 can investigate vertical salt distribution and soil/ water salinityvertical salt distribution and soil/ water salinity
up to 3, 6 and 10 m depth
Modern EM tool: DUALEM-21
DUALEM 21DUALEM‐21Theoretical depth of ECa measurement
S.N
EMS t
Depthl d( )
Variety of DUALEM Systems
No System resolved(m)1. DUALEM-2 3 (1)2. DUALEM-21 3 (4)3. DUALEM-421 6 (6)
Geonics EM38 0 0 5 m
( )4. DUALEM-642 10 (6)
Operating Frequency: 9.0 kHz
Geonics EM38 0‐0.5 m
0‐1.5 m0‐1.0 m
0 3 0 m0‐3.0 mDUALEM‐21
DUALEM-21 http://www.dualem.com/
Survey Transect & Soil samples at Nain Farm
Data point:3349Data point:3349Soil sampled points: 32
Site Salinity Assessment
Nain Field
Survey Transects32 Sample Locations at Nain Farm32 Sample Locations at Nain Farm
4 depth soil samples (0-15 15-45 45-75 &
Total soil samples collected: 128 (32x4) (8-9 Jan 2016)
(0 15, 15 45, 45 75 & 75-105 cm)
(10 11 Jan 2016)
Mokhra Kheri FieldTotal soil samples collected: 96 (24x4)
(10-11 Jan 2016)
55.560
0‐15 cm 15‐45 cm 45‐75 cm 75‐105 cmSoil salinity sample and depth wise at Nain Farm
50
ECe 12 soil samples (37.5%) Ece < 4.0
20 samples (62.5%) with ECe range 4.12 to 55.5
32.8 32.1 33.2
30
40
14.6216.54
12.51
19.55 19.820
10.311.07
4.763.15 3.652.88 1.6
3.024.343.563.232.656.06
5
8.96
2.224.984.123.94 3.8
1.82
5.743.98
8.17
0
10
01 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Sampling point ID
St ti ti f EC f 32 l t N i F )Statistics of ECe of 32 samples at Nain Farm)
Depth (cm) n Min Mean Median SD Max Skewness
0-15 32 1.60 10.8 4.87 12.2 55.5 2.2
15-45 32 0.81 7.6 5.29 6.8 30.8 1.7
45-75 32 0.93 9.9 7.36 8.6 38.0 1.4
75-105 32 1.00 10.1 6.79 8.3 28.0 0.7
EM Data of Nain Site
2D EM Conductivity Images of Four Receivers
1m Hcon(0-1.5m)
2m Hcon(0-3 m)
1m Pcon 2m Pcon(0-0.5m) (0-1.0m)
Quasi-2d and 3d inversion modellingQuas d a d 3d e s o ode gWE CAN use a
single frequency and multiple array technology
Inversion modelling parametersForward modelling: CF or FS (Maxwell) multiple array technology
DUALEM
g ( )
Inversion algorithm:Occam’s regularization with S1 or S2
( )
+2D/3D inversion software
DUALEM‐21Dampness factor (λ): 0.07-3.0
Best Inversion Results:
EM4Soil
/3Best Inversion Results: Cumulative function(CF) forward modeling,
l h d d EM4Soil
Quasi‐2D/3D Module
S2 inversion algorithm, and damping factor λ (0.07)
To generate 3D salinity Images
Salinity inversion modelling results (32 sets)Salinity inversion modelling results (32 sets)
Q3D Results
Coefficient of determination (R2) between soil ECe andCoefficient of determination (R ) between soil ECe and apparent electrical conductivity (ECa) at Nain Farm and between True ECe and ECe
Depth (cm) 1mPcon 1mHcon 2mPcon 2mHcon
0-15 0.90 0.82 0.85 0.69
15-45 0.78 0.79 0.81 0.76
45-75 0.70 0.75 0.77 0.83
75-105 0.60 0.64 0.67 0. 73
Best Parameters Regression model between True ECe and ECe
0 07 S2 CF R2 0 780.07, S2, CF R2=0.78
Inverted ECe Images (Nain Field)(0-0 2m) (0 2 0 5m)(0-0.2m) (0.2-0.5m)
(0.5-0.8m) (0.5-1.1m)
Seven depths, Z= 0-0.2, 0.2-0.5, 0.5-0.8, 0.8-1.1, 1.1-1.5, 1.5-2.3 and 2.3-3.3 m
3D Conductivity Images (Nain Field)
Layer 1: < 0.2 m Layer 2: 0.2-0.5 m Layer 3: 0.5-0.8 m yLayer 4: 0.8-1.1m Layer 5: 1.1-1.5 m Layer 6:1.5- 2.3 m Layer 7:2 3 3 3 mLayer 7:2.3- 3.3 m
3D Conductivity Images (X‐Cut)
3D Conductivity Images (Y‐Cut)
Mapping salinity in 3D Mokhra Kheri sitepp g y
Salinity Management Strategies
• Pre-reclamation management components
• Reclamation components
P l i• Post-reclamation management components
Salinity Management StrategiesGroup/sub‐group Technology/StrategiesGroup/sub group Technology/StrategiesReclamation Surface & Subsurface drainage
On‐farm land development including surface drainage Leaching Leaching
Management
Crop management
Selection of crops and cropping sequences Exploitation of varietal differencesCrop management Exploitation of varietal differences Improved agronomic practices
Soil management Land forming/seeding Application of additional nutrients
Irrigation water management Shallow depth‐high frequency irrigationPre/post‐sowing irrigationPre/post sowing irrigationSwitchover to improved irrigation techniquesLeaching for salt balance
Chemical management A li ti f h i l d t ( )Chemical management Application of chemical amendments (gypsum)
Rainwater management In‐situ rainwater conservation, Rainwater harvesting and reuse, Fallowing
Conclusions •Conclusions
• Dual geometry multiple coil EM methodology tested hasshown its potential for rapid salinity assessment across
• .
shown its potential for rapid salinity assessment acrossaffected field and with depths.
• Salinity inversion (EM4Soil) software inverts ECa data withbest inversion parameters to generate 2D/3D salinity mapsbest inversion parameters to generate 2D/3D- salinity mapsof sites using 2D/ 3D quasi-inversion modeling.
• The modelled ECe values showed the close match with theb d EC l f N i Fi ld (R2 0 78)observed ECe values for Nain Field (R2 = 0.78).
• DUALEM technology makes salinity mapping both spatiallyand vertically a single step process and thereby a efficienty g p p yway of generating 2D/3D digital soil salinity maps foreffective salinity management
