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ASSESSMENT OF WATER QUALITY FOR IRRIGATION: A CASE STUDY IN PUNJAB. AMINA MUMTAZ Senior Scientific Officer PCSIR Laboratories Complex, Lahore. ECONOMY. Role of agriculture in economy. SAP –PK Blob ,2010. INTRODUCTION.

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ASSESSMENT OF WATER QUALITY FOR IRRIGATION: A CASE STUDY IN PUNJAB

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ASSESSMENT OF WATER QUALITY FOR IRRIGATION: A CASE STUDY IN PUNJAB

AMINA MUMTAZ

Senior Scientific Officer

PCSIR Laboratories Complex,

Lahore


ECONOMY

Role of agriculture in economy

SAP –PK Blob ,2010


INTRODUCTION

  • Soil salinity and sodicity problems are common in arid and semiarid regions because of insufficient rainfall.

  • Nearly 10% of the total land surface is covered with different types of salt affected soils.

  • 954 million hectors of saline soil is present on the earth’s surface. All these salt affected soils are distributed throughout the world.


Saline Soil Distribution on Earth


Cultivatable Area in Pakistan


DISTRIBUTION OF SALINE PATCHES IN PAKISTAN (million hectares)


Salt affected land in Pakistan (million hectares)

Industry & Economy, 2000,08


AGRICULTURAL CONSTRAINS

The major constraint faced by agriculture in Pakistan:

  • Low availability and productivity of water

  • Primitive nature of farming

  • Water-logging and salinity

  • Problematic marketing system

  • Complex agriculture credit institutions

  • Inadequate research and extension services


Contd…

Engineering News, 2010,43(10): 39

  • Under utilization of land resources

  • Achievable yield potential

  • Non-development of rain fed areas

  • Dwindling land area

  • Poor infra-structure

  • Pricing and quality of inputs

  • Wasteful irrigation system and methods and

  • Unchecked population growth


IRRIGATION WATER QUALITY CRITERIA

Soil scientists use the following categories to describe irrigation water effects on crop production and soil quality:

  • Salinity hazards: total soluble salt content

  • Sodium hazards: relative proportion of sodium to calcium and magnesium ions

  • pH: acidic or basic


  • Alkalinity: carbonate and bicarbonate

  • Specific ions: Chloride, sulphate, nitrate etc.

    Other potential irrigation water contaminants that affect suitability for agricultural use include

  • Heavy metals

  • Microbial contaminants

IRRIGATION WATER QUALITY CRITERIA, 2011,29: 0.506


Water Quality Guidelines

  • Water quality criteria- Not absolute

  • Water suitability

    • Soils

    • Management

    • Drainage

  • A ten-fold range in the salt tolerance of plants gives wide scope for utilizing water of different quality.

  • Referred guidelines are


Irrigation Water Quality Criteria


Conditions of water use and irrigation quality parameters by WWF

Engineering News, 2010,43(10): 53


Effects of Poor Quality Water

Both plant and soil problems can occur due to poor quality waters.

  • Plant Factors

  • Soil Factors


Plant Factors

Salinity

  • High soil salinity reduces the availability of soil water to the plant and induces a drought condition i.e. osmotic effect

  • The severity of the osmotic effect may vary with the plants growth stage and in some cases may go unnoticed because of a uniform yield decline over the whole crop

  • Symptoms such as tip or marginal burn and defoliation may or may not occur


Contd…

Toxicity

  • Specific ions from the irrigation water may accumulate in the plant and reduce yields.

  • Concentration by evaporation of either water droplets on foliage or of soil water may help induce specific ion toxicities.

  • Specific ion toxicities are commonly associated with woody perennials, such as citrus, stone and other fruits and result mainly from high concentrations of Na+ and chloride (Cl-) ions or occasionally boron.


Contd…

Miscellaneous

  • Constituents such as iron and carbonate can at high levels stain plants to cause mainly cosmetic problems


Soil Factors

Permeability

  • When low salinity water is used on soils with high exchangeable sodium percentage (ESP) levels the soil disperses and becomes impermeable.

  • As a result it is difficult to supply enough water to the plant.

  • Related cultural problems include increased soil strength, crusting of seed beds, water logging and accompanying problems (disease, weeds, nutrition, etc.).

Agricultural Water Quality Criteria ,2004,30:3


WATER SUPPLY

QUANTITY ASSESSMENT

QUALITY ASSESSMENT

ANALYSIS

CHEMISTRY

EC

SAR

RSC

OSMOTIC EFFECT TOXICITY

MANAGEMENT

Soil type

Plant tolerance

SUITABILITY

SUITABILITY

Soil factor

Plant factor


Measuring the Quality of Irrigation Water

  • Electrical Conductivity

  • Ionic composition


Electrical Conductivity

  • Electrical conductivity (EC) is the most convenient way of measuring water salinity.

  • There is however no unique factor that can be applied and the factor will vary with composition and concentration. Generally, it is more convenient to use electrical conductivity as the measure of salt content.


Ionic Composition

  • Individual ions that make up the solute in water are often determined to identify specific ion toxicities and to assess the effect that the water will have on soil physical condition.

  • The latter effect is most often assessed by the sodium adsorption ratio (SAR) and residual sodium carbonate (RSC) of the water.


  • SAR is a measure of the tendency of the irrigation water to cause the replacement of calcium (Ca+2) ions attached to the soil clay minerals with sodium ions (Na+1). Sodium clays have poor structure and develop permeability problems.

  • RSC is the measure of the excess of carbonates (C03-2) and bicarbonates (HCO3-1) over magnesium (Mg+2) and calcium (Ca+2).With high RSC there is a tendency for Ca+2 and Mg+2 to precipitate in the soil, thus increasing the proportion of Na and increasing the SAR of the soil solution.

Agricultural Water Quality Criteria ,2004,30:2


Sheikhupura

Gujranwala

Case study


Irrigation Water Evaluation

Water analysis and the guidelines are the tools used in the initial assessment of the water.Sheikhupura and Gujranwala (villages) were selected for study. Water samples (tubewells) were collected in clean amber coloured 1-2 L samples bottle that were previously rinsed out with distilled water. It is imported that the samples must represent the water sources and special care may be needed to ensure that.


Comparison of EC values of samples with standards

Sheikhupura


Sheikhupura

  • Comparison of SAR values of samples with standards


Comparison of RSC values of samples with standards

Sheikhupura


Comparison of Chloride ions values of samples with standards

Sheikhupura


Comparison of EC values of samples with standards

GUJRANWALA


GUJRANWALA

  • Comparison of SAR values of samples with standards


GUJRANWALA

  • Comparison of RSC values of samples with standards


Comparison of Chloride ion values of samples with standards

GUJRANWALA


Sheikhupura

Gujranwala

Comparative analysis of Water quality criteria between Sheikhupura and Gujranwala


SUGGESTIONS

Drainage

The most important requirement for irrigated agriculture. It is essential that either an underground or an open surface drainage system must be implemented in the region.

Land preparation

It is essential that fields under irrigation must be leveled through land grading as it provides uniform water application which is important for leaching.


  • Crop rotation

    When it is possible, crops of high salt tolerance should also be included in the cropping system.

  • Irrigation methods and management

    Border and basin methods should be preferred in order to minimize Salinization risk when good quality water is not available.

  • Leaching

    Saline soil may be improved by leaching salts from the root zone.


THANK YOU


Proposed pH value by WWF


Tube well Sheikhupura


Canal Water


Tube well Gujranwala


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