Water Demand and Supply
Analysis
Contents
1. National Water Resource Plan(2006~2020)
2. Water Demand Forecast
2-1. Domestic water use and demand
2-2. Agricultural water use and demand
3.3. Industrial water use and demand
1. National Water Plan(2006~2020)
1. Purpose of National Water Resources Plan
To provide vision and strategy of future water resources
To pursue national economic growth and improved quality
of life
To conserve the sustainable national environment
To manage the uncertainties of floods and droughts in the
Future
2. History of National Water Resources Plan
Creation of a multipurpose
dams
Water Resources Development
Ten-Year Plan(1965)
Creation of dams and
flood control projects
Comprehensive
Long-Term Water Resource
Development plan(1980)
National Water
Resource Plan
(1990)
Development and management of
water resources
Establishment of safe water
environment and safe water use
Supplemental
National Water
Resource Plan(1996)
National Water
Resources Plan
(2001)
Creation and management of
environmentally friendly water resources
3. Vision and Strategy
Vision
Sustainable Water Management Required by Humanity and Nature
Water Use Plan
Supply sufficient and clean water for the
public and nature
Flood Control Plan
Improve society’s ability to respond to flood hazards
River Environment Plan
Restore natural river environment where nature
and humans can exist in harmony
Investigation & R&D Plan
Advance water resources information and technology
Goal
- Water Use policy, increase efficiency of existing facilities
- Basin-based flood control measures, for example adoption of flood
Strategy
allocation system, adjustment of land use plan and etc.
- Reinforce evaluation, conservation and restoration of river environment
- Expansion of water resource investigations and national R&D
4. Current Problems
Weak stability and equalization of regional water supply
Limited water resource developments and conflict of water
use between upstream and downstream
Weak evaluation of achievements by the management of
Water demand policy
Calling for social demand for river instreamflow
Insufficient ability to respond to unexpected droughts
5. Water Resources in Korea
(unit: billion ㎥/year)
Total Water Resources
124.0(100%)
River Discharge
72.3(58%)
Discharge from Flood
52.2(42%)
Lost to Sea
38.6(31%)
Loss
51.7(42%)
Regular Discharge
20.1(16%)
Used as River Water
12.3(10%)
Used for Dam
17.7(14%)
Total Use
33.7(27%)
Used as Groundwater
3.7(3%)
6. Water Use
Due to population increase and economy growth
water use amount abruptly increased
From 1965 to 2003 6.6 times
'65
(unit : billion ㎥)
5.1
'80
Domes tic
15.3
'90
Indus trial
24.9
Agricultural
30.1
'94
'98
Ins tream flow
33.1
33.7
'03
0
10
20
30
40
50
7. Methodology for Determining Water Demand
Full discussion regarding future water demand with
Expert Groups
Set Scenarios(high, medium and low demand) to consider
uncertain prospect of future water demand
Domestic water : time series analysis to reflect decrease in water
use/person/day, scenarios by water demand management
Industrial water : per unit production cost to reflect water amount used for
manufacturing, scenarios by growth of the economy
Agricultural water : allotted to certain portion of land space
River Instream flow : discharge for conservation and/or average
water minimum discharge, scenarios by farmland space
7. Scenarios for Determining Water Demand
Scenarios to consider limits of data used for estimation and uncertainty
of future socioeconomic prospects
8. Prospects on Water Demand : Domestic Water
648 million ㎥ decrease in domestic water demand of medium
scenarios predicted in 2001
by decrease in population (50,855 →49,783 thousand person) and water
use/person/day (411L→363L)
10
Domestic Water Demand(billion ㎥/year)
'01 Water Resources Plan
High Demand
9
Medium Demand
Low Demand
8
7
6
5
1998
2001
2003
2006
2011
2016
2020
yr
9. Prospects on Water Demand : Industrial Water
865 million ㎥/year decrease in industrial water demand of medium
scenarios predicted numbers in 2001
by increase in water reuse (30 million ㎥/year →780million㎥/year) to
reflect Water Recycle Policy
6
Industrial Water Demand(billion ㎥/year)
'01 Water Resources Plan
High Demand
5
Medium Demand
Low Demand
4
3
2
1
1998
2001
2003
2006
2011
2016
2020
yr
10. Prospects on Water Demand : Agricultural Water
344 million ㎥/year decrease in agricultural water demand of
medium scenarios predicted numbers in 2001
by reduction of field land space (1,850 thousand ha →1,754 thousand ha)
18
Agricultural Water Demand(billion ㎥/year)
'01 Water Resources Plan
High Demand
17
Medium Demand
Low Demand
16
15
14
13
1998
2001
2003
2006
2011
2016
2020
yr
8. Prospects on Water Demand : River Instream Flow
No change in the amount predicted in 2001 (8.4billion㎥)
River instream flow is settled applicable management discharge
considering physical supply possibility
Han River, Nakdong River, Geum River : demand necessary for conserving water
quality
Yeongsan River · Sumjin River : demand necessary for conserving water quality
Other River : average minimum discharge
9. Prospects on Total Demand
35.5 billion ㎥/year in 2011(medium scenarios)
1.9 billion ㎥/year decrease in medium demand predicted
numbers in 2001 (37.4billion ㎥/year in 2011]
1.2 billion ㎥ decrease in high demand
45
'01 Water Resources Plan
Water Demand(billion㎥/year)
High Demand
40
Medium Demand
Low Demand
35
30
25
1998
2001
2003
2006
2011
2016
2020
yr
10. Water Resources Development and Supply
Dam Storage (unit : million ㎥)
Hydropower dam 10
888(6.7%)
River barrage 5
449(3.4%)
Groundwater Use in 2003
(unit : million㎥/yr)
Others
47(1%)
D&I dam 16
431(3.3%)
Agricultural
1,659(44%)
Agricultural reservoir
18,000
2,772(21%)
Effective storage
Total 13,194
Multipurpose dam 15
8,654(65.6%)
note) dam developed by 2003
Total
3,745
Domestic
1,847(49%)
Industrial
197(6%)
11. Future Water Supply & Demand Prospects
Total water shortage 340 million ㎥ by supply facilities expansion
like regional supply of surplus water resources and etc.,
2016 yr
2020 yr
12. Plan Details
Reinforce sound water use system through demand & supply
management
Secure regional equalization and stability of water use
Conserve water quality and river ecosystem through
restoration of river discharge
Create water resources reflecting regional characteristics
and economic efficiency
Efficient use and conservation of groundwater
Enhance ability to respond to unexpected droughts
Foster water resources cooperation between North Korea
and South Korea for the rivers shared by two countries
2. Water Demand Forecast
Why do we care?
Project design issues
Contractual issues
Environmental impacts
Strategic planning
Operations planning
Appraisal of demand-management policies and innovations
Financial impacts
Public Confidence
What is “Demand?”
Demand : The amount of water desired by the
consumer base :
Price
Weather
Season
Time
Economic setting
Forecasting Water Demand and Use
Background
At a catchment level demand forecasting should be
carried out for each of the major demand sectors.
These are :
Environment (instream flow)
Urban(rural) domestic
Industry
Agriculture
Forecasting Water Demand and Use
Influences on water demand and use
There are many influences that affect water demand and
water use. Some of the most commonly cited factors are
related to :
Population
Level of service
Tariff levels
Demand management measures and increased efficiency in
water use
Climatic conditions
Forecasting Water Demand and Use
Criteria for assessing forecasting methods
There are numerous methods to forecast water demand
* To assess alternative forecasting methods it is necessary
to establish criteria by which the methods can be judged
- Suggested criteria are as follows :
Consistency and transparency of the method
Logical/theoretical appeal of the method
Method incorporates and explains historical trends
Empirical validation of the method
Forecasting Water Demand and Use
Choice of forecasting method
There are no simple rules that can be used to establish
which water demand forecasting method should be used
In deciding which method to use in predicting future
water demands, a balance needs to be made between:
The level of accuracy of the forecast required
The cost of obtaining the required level of accuracy
The benefits accrued from having a higher level accuracy
Forecasting Water Demand and Use
The advantages of producing as accurate forecasts as
possible are as follows
Reduces the mis-allocation of resources and allows investment decisions to be
delayed
Enables the effects of water resource polices to be examined with confidence
Identifies areas and sectors to be targeted for conservation programs
Forecasting Water Demand and Use
Check list for determining the forecast method
Before deciding which forecasting methods to be
implement, the following questions should be considered :
What were the previous forecast and are results available?
What were the previous forecast errors and why did they occur?
What data is available and over what period and what is the level of accuracy?
What are the possible forecasting methods available?
Which of these are feasible given the various constraints on
data, budget and skills available to implement these methods?
Do additional data required for future analysis?
Forecasting Water Demand and Use
Incorporating uncertainty into forecasting
Uncertainty is an integral part of water demand forecasting
All forecasting methods for water demand and use are
subject to uncertainty
Uncertainty is therefore better considered through the
construction of various scenarios
Water demand
Higher growth
Medium growth
Lower growth
Past
Present
Future
Forecasting Water Demand and Use : Domestic
Details of forecasting methods
There are a number of forecasting methods that are
commonly used to predict future water demands and use.
These include :
Extrapolation of historical data and trend analysis
Forecasts based on population growth and per capita consumption
Component analysis
Multiple linear regression analysis
Multiple non-linear regression analysis
Forecasting Water Demand and Use : Domestic
Example of forecasts using trend analysis
- Results of trend analyses using different fitting techniques
Second degree polynomial fit
Exponential fit
Linear regression
Forecasting Water Demand and Use : Domestic
Forecasts based on component analysis
The component analysis technique allows estimates of
water use to be based upon an individual component
Components of an urban water supply system
Household level components
Forecasting Water Demand and Use : Agricultural
Agricultural water demands are primarily a function of the
following:
Meteorological condition
Cropped area for each type of crop
Type of irrigation method and irrigation efficiencies
Water charges
Forecasting Water Demand and Use : Agricultural
The irrigation water demand and use can be established
from :
Estimates using empirical formula
Measurements of water consumption from flow gauging devices
Field measurements of the consumptive use of crops
Forecasting Water Demand and Use : Agricultural
Use of empirical equations to calculate irrigation water
demand
Calculation of reference crop
evapotranspiration ET0
Estimation of effective rainfall
Pe
Calculation of irrigation
demand IR=ET0 -Pe
Estimate overall irrigation
efficiency Ei
Calculation irrigation water use
Use = IR / Ei
Forecasting Water Demand and Use : Agricultural
In order to conduct a detailed estimate of irrigation
water demand and use, using formulae, the following
information is required
Reference crop evapotranspiration
Crop type and crop evapotranspiration
Cropped area
Effective rainfall
Soil type and leaching requirements
irrigation efficiencies
Forecasting Water Demand and Use : Agricultural
Method of estimating reference crop evapotranspiration
- The reference crop evapotranspiration is based on a
hypothetical, well-watered grass reference crop with
specific characteristics
Blaney-Criddle method
Radiation method
Pan evaporation method
Penman-Monteith method
Forecasting Water Demand and Use : Agricultural
Penman-Monteith method
- This method is recommended for use where possible
there is sufficient meteorological data
Where : Rn is the net radiation at crop surface
G is the soil heat flux
T is the average temperature
U2 is the wind speed measured at 2m height
(ea-ed) is the vapor pressure deficit
is the slope vapor pressure curve
is the psychrometric constant
Forecasting Water Demand and Use : Agricultural
Penman-Monteith method
Advantages of Penman-Monteith method
- The FAO of the United Nations recommend the use of
the penman-Monteith equation
- Climate data and tools to assist with the calculation of
ET0 using the Penman-Monteith method are available
from the FAO
- The method can be used to estimate ET0 on a daily basis
Disadvantages of Penman-Monteith method
- This method requires a considerable amount of climatic
data
Forecasting Water Demand and Use : Agricultural
Estimation of the crop coefficient
The crop evapotranspiration ETcrop in mm/day is calculated by
multiplying the reference crop evapotranspiraing ET0 in mm/day
by a dimensionless crop coefficient Kc
The crop coefficient is dependent on the following factors
- Crop type
- Climate
- Soil evaporation
- Group growth stage
Forecasting Water Demand and Use : Agricultural
Estimation of the crop coefficient
Typical crop coefficient curve
Initial Stage when the leaf area is small and majority of the ET is due to
soil evaporation
Crop development Stage when the leaf area grows from approximately
10% to full ground cover
Mid-season Stage when the crop is reaching maturity
Late Stage runs from the start of maturity to the harvest
Forecasting Water Demand and Use : Agricultural
Estimation of Effective rainfall
The proportion of the rainfall that is useful for crop
production. There are several factors that affect effective
rainfall including :
- Rainfall characteristics
- Soil type
- Groundwater characteristics
- Management practices
There are several empirically based methods available
- Renfro equation
- US Bureau of Reclamation method
- Us Department of Agriculture Soil Conservation Service
method(often used)
Forecasting Water Demand and Use : Agricultural
Irrigation efficiencies
The ratio of water consumed by crops to the water diverted
from source
- The overall irrigation efficiency is made up of the Ec, Eb and Ea
Forecasting Water Demand and Use : Agricultural
Livestock water use
The water requirements of livestock are influenced by several
factors, including :
- Type of livestock
- Lactation
- Feed intake
- Pregnancy
- Type of diet
- Temperature
Estimating total livestock consumption is relatively simple
- Determine types of livestock
- Use typical water consumption figures per head for each type
of livestock
- Determine number of each type livestock in the area being
assessed
Forecasting Water Demand and Use : Agricultural
Livestock water use
Forecasting Water Demand and Use : Industrial
Industrial water use includes water used for the following
- Industrial process such as fabrication, processing,
washing and cooling
- Mining
- Hydropower generation
- Thermal electric power generation
Forecasting Water Demand and Use : Industrial
The factors affecting water demand vary widely between
the different industrial operations.
* The major factors common to the industrial and
commercial sectors in determining water demand are :
- Economic activity at a local, national and international level
- Population
- Industrial composition
- Price water
- Access to supply and alternative supplies
- Access to technology
- Working practices
Forecasting Water Demand and Use : Industrial
Although information on industrial water use is often
available from meter records, additional information may
be required to establish industrial water use including
- Type of industry
- Expected rates of growth or decline of industry sector
- Percentage of industries connected to the public supply
- Tariff levels for water
- Extent of the use of water saving technologies
- Extent of conservation measures on demand
- Government incentives
Forecasting Water Demand and Use : Industrial
Water supply, use and treatment for a typical industrial
plant
Forecasting Water Demand and Use : Industrial
Water use surveys can be carried out through the use of
questionnaires
Example of an industrial water use questionnare
Forecasting Water Demand and Use : Industrial
Forecasting industrial water demand and use
* The simplest approach to forecasting industrial water
demand and use is to carry out a trend analysis as follows
- Establish the relationship between industrial production and
water use for various sectors
- Assess the trends in industrial production
- Project trends in industrial production into the future to
establish the future water use
Forecasting Water Demand and Use : Industrial
Forecasting industrial water demand and use
* GDP has become a common variable used in demand
forecasting models. Past studies in a number of countries have
shown that there is a reasonable correlation between GDP and
industrial use
Example of a relationship between GDP and industrial
water demand
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