Environmental Demand for water resource planning

Dr Nick Marsh

30 May 2012

CLIMATE CLIMATE

LAND USE LAND USE

ECOLOGICAL ECOLOGICAL ASSETS

DAMS & DAMS & WEIRS

IRRIGATION IRRIGATION

CITIES CITIES

Demand Demand

Demand Demand

Volume of augmented flow

Commence to fill trigger

ML/d

days

Environmental Water requirements are all about:

Rate of Change (Pattern)

Magnitude

Duration

Frequency

Timing

Photo : Hattah Lakes : DEWHA

eFlow studies identify important flow components

eFlow studies identify important flow components

Ma

gn

itud

e

Du

ratio

n

Fre

qu

en

cy

Tim

ing

Shared code with

Four different ‘Flow Rules’

1. Baseflow

2. Highflow

3. Pattern

4. Translucency

Different approaches to defining water needs

Photo courtesy of TRaCK

Model set up

Input time series

Forecast parameters

Collection of flow rules

Link to eFlow Predictor

Baseflow Rule: minimum flow requirement

What time of year is important?

Add up short floods to a minimum

percentage of time or days duration

What is the minimum duration to

consider?

Flow threshold? – natural drought?

Flood / Fresh Rule: high flow event

Continuous flood, add up short floods or

specify a number of floods

Are there maximum rates of rise and fall

restrictions?

Days

Rate (ML/D)

Percentage – daily percentage change

If multiple spells should there be a gap

between them?

If multiple small spells, is there a minimum

duration?

Specify the shape of the flow

pattern

Flow pattern rule: Specific hydrograph shape

Translucency: allow flow to pass through a dam

Look to some upstream

node as the basis for the

translucency

Define the end of the event

either by Volume of dropping

below a threshold

Augmentation strategy for each flow rule

Use the natural flow to trigger and event

start.

If you are in an event, then extend it

(piggy backing)

Force a release of water to make sure

the rule is met at some interval

0

5000

10000

15000

20000

25000

30000

35000

40000

5/1/1903 0:00

6/1/1903 0:00

7/1/1903 0:00

8/1/1903 0:00

9/1/1903 0:00

10/1/1903 0:00

11/1/1903 0:00

12/1/1903 0:00

Natural

Natural frequency

Extend

Force

Same forest, different year, different water needs

Conditional Rules: wet years vs dry years

Photos courtesy of the Living Murray Program (Koondrook-Perricoota)

For crop water demand, based on water availability we will either put in

a crop or not. We are not interested in a partially successful crop.

For the environment we have to consider:

Triage – when there is no water around but things are nearly dead what

are our priority assets

Maintenance – for ‘average’ water years we want to keep adults

healthy

Recruitment – in wet years like 2010 we want to create flood events so

that everything can reproduce.

We need a system whereby we can predefine each of these conditions

and allow the environmental demand module to select which flow rule

should apply.

Multiyear variability in demand: ‘Condition’

Flow rule collections allows variable rule selection

Consider these rules all the

time

Only consider one of these

rules each time step

Environmental Demand Module in Source can be used to

create models of environmental demand that are:

• sophisticated,

• multiyear,

• conditional

You can involve non-hydrologists in the process by

developing and testing the environmental demand in:

Key Points