Water Uses

Nadim Farajalla, PhDEnvironmental Hydrologist

American University of Beirut

• Water resources are exploited for use in the following sectors:– Agriculture– Municipal/Domestic– Industrial– Recreational

• A non-exploitation use is:– Ecological

Domestic/Industrial Sector

• The following are the supply oriented components:– Sources of water supply– Treatment facilities– Storage facilities– Distribution networks– House/establishment connections

Domestic/Industrial Sector

• The general wastewater components are:– Sources– Collection networks– Treatment facilities– Discharge locations

Why Treat Wastewater?Odor generation Unpleasant odors from raw sewage disposal

Water Quality Pollution due to high BOD, high nutrient load, pathogenic organisms, suspended solids, etc.

Public Health High incidence of waterborne diseases

Biodiversity • Possible negative impact on fauna and flora;

• Coastal degradation

Agriculture Irrigation with raw sewage - possible contamination of soil and crops

Economic Aspects • Cost of treating illness;• Cost of lost working days due to illness;• Indirect costs of water treatment;• Loss in national income (decrease in

tourism and investments)

Visual Impact Impact on natural landscapes and amenity value

Reuse and Recycle• An average household may generate

135 to 180 m3 of wastewater annually:

• Irrigation:– Some crops– Silviculture (Managed Forests)– Golf Courses– Landscaping

• Graywater Recycling:– Use for flush toilets

Agriculture

5,5005,000

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Wate

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Total use

Agricultural use

Industrial use

Domestic use

1900 1920 1940 1960 1980 2000Year

Global Water Use

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World Irr

igate

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Mha)

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World P

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billions)

1800 1850 1900 1950 2000 2050 Years

World Pop.

Irrigated Area

ha per 1000 people

Global Water Use

Rapid growth in domestic and industrial water demand

Increasing costs of water development

Wasteful use of existing water supplies

Groundwater over-pumping and degradation of irrigated cropland

Threats to ecosystems, declining water quality

Subsidies, distorted incentives, and poor cost recovery

Low rainfed crop yields

Key Challenges for Agricultural Water Resources

EffectiveWater Resources

Use For AgriculturalProduction

Natural Factors•Precipitation•Evapotranspiration

Infrastructure•Reservoir storage•Water distribution and • use systems

Water Policies•Water allocation among sectors•Water prices•Committed flow for environment•Investment in infrastructure

Water Pollution

Variables Influencing Agricultural Water Resources

Water in Agriculture

• Two major water components/systems in agriculture:– Water delivery systems (canals,

reservoirs, etc)– On-farm systems (irrigation systems,

storage facilities, etc.)

Inefficiencies in Water Conveyance and Irrigation System Maintenance

• Poor management of irrigation systems leads to conveyance losses of up to 50 percent

• The social benefit of canal maintenance is greater than the private benefit. Ignoring this has led to under investment in canal maintenance, resulting in:

– shorter canal systems than optimal

– over-application of water upstream

Inefficiencies in Farm-level Water Management

• Poor farmer selection of crops and irrigation technologies

• Conservation technologies increase water use efficiency but some may lead to higher cost per acre

• There are low tech “drip” like technologies – but are unused

• Low pricing of water does not justify adoption of water conservation approaches and technologies

• Effective pricing of water and charges on drainage water quality will lead to adoption of water conservation approaches and technologies

System Ownership

• Water systems run by a water user associations are more efficient and better maintained (Madagascar, India, China).

• WUA tax members and improve distribution and pricing.

Options for Improvements

Options for Improving Water Use in Agriculture [adapted from Wallace and Batchelor (1997)]

1. Agronomy:• Crop management to enhance rainfall use

or to reduce evaporation (crop residues, conservation tillage, plant spacing);

• Improved varieties; and

• Advanced cropping strategies (double-cropping, rotations) to take advantage of lower water demand times or periods with higher rainfall.

Options for Improving Water Use in Agriculture [adapted from Wallace and Batchelor (1997)]

2. Engineering:• Irrigation systems that reduce

application losses and improve application uniformity;

• Enhanced rainfall capture (crop residues, deep chiseling, furrow diking, etc.)

Options for Improving Water Use in Agriculture [adapted from Wallace and Batchelor (1997)]

3. Management:• Demand-based irrigation scheduling;

• slight to moderate deficit irrigations to promote deeper soil water use;

• avoiding exceeding critical root zone salinity levels; and

• preventative maintenance of equipment

Options for Improving Water Use in Agriculture [adapted from Wallace and Batchelor (1997)]

4. Institutional:• User participation in district (project)

operation and maintenance;

• water pricing and legal incentives to reduce water use and penalties for inefficient use; and

• training and educational opportunities

Caveat

• When considering water allocation the following must be considered:

– Water in agriculture supports more than crop production – it sustains a way of life

Concepts

Water Productivity – Definition

• Physical: Amount of marketable product (e.g. kg rice) per volume of water used

• Economic: $ output per $ water used

• Combined: Value ($) of output per volume of water used

“More Crop Per Drop”

Water Productivity Principles

• Enhance marketable yield of crops for each unit of water transpired

• Reduce water losses other than those lost to evapotranspiration

• Enhance the effective-use of rainfall, water stored in the domain of interest, and water with marginal quality.

Water Productivity -

Make Existing Systems More Productive

• Strengthen management• Ensure integrity of infrastructure• Rehabilitate existing investments• Improve on-farm water use• Participatory management by

farmers• Private sector in investments and

management

Virtual water

• Value of water varies by location.

• Defining a water shortage as a situation where water per capita is below a certain level is not always useful.

• A region with minimal water can use it productively and generate resources to buy water intensive crops at a cheaper rate than producing them locally.

• For example, an acre-foot of water used in flower production is equivalent in the value of productivity to 30-40 acre-feet used in wheat.

Water Security

Water Security• Context

– Worldwide, more than 1 billion people lack access to safe drinking water.

– 80 percent of the earth’s urban residents may not have adequate potable-water supplies.

– Around 0.008% of fresh water is currently available.

Addressing Water Security

• Integration of water resources fully into the planning process

• Continued reform and capacity building

• Development of water resources infrastructure

• Reappraisal of existing investments

• Recognition of climate change and/or variability as risks to be managed

Addressing Water Security

• Increased water productivity• Water for food• Water for power generation• Water for environmental functions

• Diversification of type and size of interventions

• Diversification of financing mechanisms• both public and private

Food Security

FOOD SECURITY vs. FOOD SELF-SUFFICEINCY

– Food security is “…people having access to sufficient stocks and supplies of food to provide a nutritionally adequate diet”

– Food self-sufficiency: a country growing its own basic food requirements

What do you think…………

• Food security or food self-sufficiency?

• Water security or food security?

• Water security or food self-sufficiency?