B.TECH FINAL YEAR Slide 1: Water Quality Index Development
01 / 09
B.TECH FINAL YEAR PROJECT (MIDTERM)

Water Quality Index Development of
Jhajjar Distributary Region

WQI Modeling & Irrigation Suitability Assessment

Introduction: River Water and Groundwater

Surface Water vs. Groundwater Dynamics

RIVER / SURFACE WATER
  • Fed by rainfall, runoff, canals and distributaries
  • Exposed to sewage, industrial waste and agricultural runoff
  • Quality changes with season and flow variations
  • Jhajjar Distributary: ~25 km canal from Bhalaut to Dhaur
  • Receives domestic & agricultural return flows
  • High variability in TDS, EC and coliform counts
  • Seasonal dilution during monsoon, concentration in summer
  • Critical source for downstream irrigation & drinking supply
GROUNDWATER
  • Stored in alluvial aquifers of Indo-Gangetic plain
  • Accessed via tube wells, hand pumps & bore wells
  • Natural contaminants: Fluoride, Arsenic, Iron, Nitrate
  • Human-induced pollution: Pesticides, fertilizers, leachate
  • Slow recharge rate → pollutants persist for decades
  • Jhajjar district: Groundwater is primary drinking source
  • Declining water table due to over-extraction

A Water Quality Index (WQI) combines many parameters into a single score to judge water for drinking and irrigation.

PHYSICOCHEMICAL WATER QUALITY PARAMETERS (12 PARAMETERS)

Analyte Breakdown, Geochemical Origins & Environmental Significance

Analyte / Parameter (Symbol) Hydrochemical Significance & Toxicological Risks
pH (Acidity/Basicity) Controls chemical speciation, heavy metal solubility, corrosivity, and palatability (Standard: 6.5–8.5).
TDS (Total Dissolved Solids) Bulk indicator of mineral dissolution and salinity hazard; causes osmotic stress and gastrointestinal irritation.
Calcium (Ca²⁺) Leached from calcite and dolomite; primary contributor to total hardness and household/boiler scaling.
Magnesium (Mg²⁺) Hardness contributor from ferromagnesian minerals; exerts laxative purgative effects at elevated levels.
Sodium (Na⁺) Silicate weathering and saline intrusions; critical driver of soil alkalization, dispersion, and sodicity hazard.
Potassium (K⁺) Derived from orthoclase feldspar and NPK agricultural fertilizers; vital micronutrient with low baseline levels.
Total Alkalinity (TA) Buffering capacity against acidification driven by HCO₃⁻/CO₃²⁻ from carbonate rock weathering.
Chloride (Cl⁻) Conservative chemical tracer; elevated levels indicate municipal sewage, septic discharge, or saline backwater.
Sulphate (SO₄²⁻) Gypsum dissolution and industrial runoff; causes bitter taste and cathartic laxative distress at >250 mg/L.
Nitrate (NO₃⁻) Percolation of nitrogenous fertilizers and sewage; poses severe infant Methemoglobinemia ("Blue Baby Syndrome") risk.
Fluoride (F⁻) Geogenic leaching from fluorite/apatite; levels > 1.5 mg/L cause irreversible dental and crippling skeletal fluorosis.
Total Hardness (TH) Sum of divalent Ca²⁺ and Mg²⁺ ions; hinders soap lathering and shortens domestic/industrial piping lifespan.

ANALYTICAL INSTRUMENTATION & TESTING PROTOCOLS

Standardized Experimental Assays, Instrumentation & Testing Procedures

Parameter / Analyte Analytical Method / Instrument Experimental Protocol & Procedure Details
pH (Potential of Hydrogen) Electrometric Method
Digital pH Meter
Measured electrometrically using a calibrated pH meter. Measures electrical potential due to H⁺ ions in solution. The measuring electrode system utilizes a standard glass electrode and calomel reference electrode calibrated with NIST standard buffer solutions (pH 4.01, 7.00, 9.20).
Total Alkalinity (TA) Titrimetric Assay
Acid Neutralization
Standard wet-chemistry volumetric titration against 0.02 N H₂SO₄ using phenolphthalein and methyl orange indicators to determine total carbonate (CO₃²⁻), bicarbonate (HCO₃⁻), and hydroxide (OH⁻) buffering capacity.
Total Hardness (TH) Complexometric Titration
EDTA Method
Complexometric titration using standard 0.01 M EDTA solution with Eriochrome Black T (EBT) indicator buffered at pH 10.0 (NH₄Cl-NH₄OH buffer) for total hardness (Ca²⁺ + Mg²⁺), with sharp wine-red to blue end-point.
Chloride (Cl⁻) Argentometric Titration
Mohr's Method
Titrimetric assay using standardized 0.0141 N Silver Nitrate (AgNO₃) in presence of Potassium Chromate (K₂CrO₄) indicator until a distinct reddish-brown silver chromate (Ag₂CrO₄) precipitate forms.
Fluoride (F⁻) Spectrophotometry
SPADNS Colorimetry
Colorimetric reaction using SPADNS reagent (Sodium 2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalenedisulfonate) and Zirconyl acid; bleaching of the red lake is measured spectrophotometrically at λ = 570 nm.
Calcium (Ca²⁺), Magnesium (Mg²⁺), Sodium (Na⁺), Potassium (K⁺) AAS
Atomic Absorption Spectrophotometry
Measured by Atomic Absorption Spectrophotometry (AAS). Quantitative determination of major cations using element-specific hollow cathode lamps and air-acetylene flame atomization against matrix-matched multi-element standard calibration curves.
Sulphate (SO₄²⁻) Turbidimetric Method
UV-Vis Spectrophotometer
Precipitation with Barium Chloride (BaCl₂) crystals in conditioning reagent medium to form uniform BaSO₄ colloidal suspension; turbidity absorbance is measured spectrophotometrically at λ = 420 nm.
Nitrate (NO₃⁻) UV Spectrophotometry
Dual-Wavelength Screening
Direct UV spectrophotometric screening at λ = 220 nm with baseline organic matter absorption correction measured at λ = 275 nm using optical quartz cuvettes.
TDS (Total Dissolved Solids) Gravimetric Method
Whatman Filtration & Ignition
Measured by filtration of water sample through Whatman filter paper (No. 42 / 0.45 µm) and subsequent drying/ignition of filtrate in a silica crucible heated at 550–650 °C to determine non-volatile dissolved mineral residue.

REGULATORY STANDARDS & PARAMETER UNIT WEIGHT ASSIGNMENT

WHO & IS 10500 Regulatory Standards & Unit Weight Penalties

Parameter (mg/L) WHO Limit IS 10500 Unit Weight (Wn) Rel. Weight
Fluoride (F⁻) 1.5 1.0–1.5 0.620 62.0% (Highest)
pH (unitless) 8.5 6.5–8.5 0.109 10.9%
Potassium (K⁺) 12 — 0.078 7.8%
Total Hardness (TH) 500 200–600 0.019 1.9%
Magnesium (Mg²⁺) 50 30–100 0.019 1.9%
Nitrate (NO₃⁻) 50 45 0.019 1.9%
Calcium (Ca²⁺) 200 75–200 0.005 0.5%
Sodium (Na⁺) 200 — 0.005 0.5%
Sulphate (SO₄²⁻) 250 200–400 0.004 0.4%
Chloride (Cl⁻) 250 250–1000 0.004 0.4%
Total Alkalinity (TA) 500 200–600 0.002 0.2%
TDS 1000 500–2000 0.001 0.1%
CRITICAL INSIGHT
72.9% Weight Dominance

Fluoride (Wn = 0.620) and pH (Wn = 0.109) together command almost three-quarters of the entire WQI penalty function.

TOXICITY THRESHOLD

Because Wn is inversely proportional to permissible standard Sn, any marginal exceedance of Fluoride above 1.5 mg/L triggers severe index inflation, categorizing water as "Very Poor" or "Unfit" for human consumption.

FIELD STUDY AREA: JHAJJAR DISTRIBUTARY SYSTEM

Western Yamuna Canal Command | Hydrological Corridor & Agricultural Lifeline

Jhajjar Distributary System Map
Jhajjar Distributary Field Study Area (WYC Reach)
Bhalaut Regulator (Head) → Dhaur Outfall (Tail) | Reach ~25–35 km | Command Area: ~18,500 ha
HYDROLOGICAL DOSSIER
Regional Agronomic & Hydrogeological Role
  • Canal Alignment & Reach: Originates from Bhalaut Regulator on the Western Yamuna Canal (WYC) system; courses ~25–35 km southwards through Jhajjar district, terminating near Dhaur outfall.
  • Command Area Served: Culturable Command Area (CCA) of ~18,500 hectares (ha) of fertile agricultural land across multiple agrarian villages in Jhajjar district.
  • Agricultural Lifeline: Provides essential gravity-fed irrigation for ~18,500 ha producing Wheat, Mustard, Pearl Millet (Bajra), and Paddy.
  • Aquifer Recharge Corridor: Acts as the primary freshwater artificial infiltration buffer that continuously replenishes shallow aquifers against regional brackish/saline groundwater intrusion.
  • Environmental Vulnerabilities: Marked tail-end conveyance losses, agricultural runoff (pesticides, nitrates), livestock washing, bank erosion, and localized untreated graywater dumping.

MATHEMATICAL FORMULATION: DRINKING (WQI) & IRRIGATION (IWQI)

Weighted Arithmetic Formulation & Agronomic Soil-Water Alkalinity Indices

DRINKING WQI FORMULATION
Weighted Arithmetic Index Method

WQI combines many parameters into a single score that tells how suitable water is for drinking by using the weighted arithmetic index method.

Step 1: Unit Weight (Wn)
Wn = K / Sn   |   K = 1 / Σ(1/Sn)
• Wn = Unit weight of n-th parameter
• Sn = Standard permissible limit
• K = Proportionality constant
Step 2: Quality Rating Sub-Index (Qn)
Qn = 100 × [(Vn - Vi) / (Sn - Vi)]
• Vn = Measured experimental value
• Vi = Ideal pure water value (Vi = 0 for chemical ions; Vi = 7.0 for neutral pH)
• Sn = Standard permissible limit
Step 3: Composite Drinking Index (WQI)
WQI = Σ(Qn × Wn) / ΣWn
• Composite weighted quality score (where ΣWn = 1.0)
IRRIGATION IWQI SUITE
Soil Permeability & Sodicity Indices

Irrigation suitability depends on salinity and sodium hazard, which affect soil structure, permeability and crop growth. It is assessed with four indices, classified separately, using ions in meq/L.

Sodium Adsorption Ratio (SAR):
SAR = Na⁺ / √[(Ca²⁺ + Mg²⁺) / 2]
Measures sodium alkali hazard & soil dispersion
Sodium Percentage (%Na):
%Na = [(Na⁺ + K⁺) / (Ca²⁺ + Mg²⁺ + Na⁺ + K⁺)] × 100
Evaluates sodium concentration vs total cations
Magnesium Hazard (MH) & Kelley's Ratio (KR):
MH = [Mg²⁺ / (Ca²⁺ + Mg²⁺)] × 100
KR = Na⁺ / (Ca²⁺ + Mg²⁺)
MH assesses magnesium toxicity; KR assesses excess sodium
(Note: All ionic values strictly in milliequivalents per liter: meq/L)

WATER CLASSIFICATION MATRIX & SUITABILITY SCALES

Potability Tiers (Drinking WQI) vs. Agronomic Thresholds (Irrigation IWQI)

DRINKING WQI MATRIX
Potability Suitability Tiers
WQI Range Classification Suitability Action
0 – 25 Excellent Pristine; direct potable consumption.
26 – 50 Good Standard domestic use; basic filtration.
51 – 75 Moderately Poor Treatment required; coagulation/filtration.
76 – 100 Very Poor Unsuitable for direct use; advanced RO needed.
> 100 Unfit Severe health hazard; prohibited from drinking.
IRRIGATION SUITABILITY
Agronomic Thresholds
Irrigation Index Range Agronomic Class
Sodium % (%Na) < 60%
> 60%
Suitable
Unfit (Deflocculation)
SAR (Richards) < 10
10–18
18–26
> 26
Excellent
Good
Doubtful
Unfit
MH (Szabolcs) < 50
> 50
Safe
Unfit (Soil Alkalinity)
Kelley's Ratio < 1.0
> 1.0
Suitable
Unfit (Na Hazard)

Our Progress

Current Milestone Status & Next Experimental Phases

COMPLETED
Milestones Achieved
  • Studied the water quality parameters and how each one is tested
  • Examined various areas and selected the Jhajjar Distributary
IN PROGRESS
Current Activity
  • Finding sampling locations and collecting samples for testing
NEXT
Upcoming Roadmap
  • Test the samples in the laboratory
  • Calculate WQI and IWQI and assess the water quality of the distributary