Small hydro sites hydrology: Optimum capacity screening and estimation of fish habitat requirements. Charles D. D. Howard Senior Advisor Charles Howard

Small hydro sites hydrology: Small hydro sites hydrology: Optimum capacity screening and Optimum capacity screening and

estimation of fish habitat estimation of fish habitat requirements.requirements.

Charles D. D. HowardCharles D. D. HowardSenior Advisor Senior Advisor

Charles Howard & Associates LimitedCharles Howard & Associates Limited

www.cddhoward.comwww.cddhoward.com

How Accurate is the Estimated Energy?How Accurate is the Estimated Energy?

Optimizing Installed Capacity for Optimizing Installed Capacity for Small Hydro on Ungauged StreamsSmall Hydro on Ungauged Streams

Is the site a good investment opportunity, Is the site a good investment opportunity,

or a risky venture?or a risky venture?

Charles D. D. Howard, P. Eng.

How much water to leave for environment?How much water to leave for environment?

Hydrology ConsiderationsHydrology Considerations


•Development of the flood frequency curve.

•Matching the penstock-turbine-generator set.

•Calculation of the energy capability.

•Economic optimisation of installed capacity.

•Assess impact of development on instream habitat

•The time series hydrograph: often unknown flows.

1.1. The simulated hydrograph of The simulated hydrograph of hourly or daily flowshourly or daily flows..

• The watershed model provides opportunities to explore the sensitivity of hydrologic sequences to factors such as tree cover, soil types, land slopes, and the range of elevation. A particular watershed can easily be “transposed” to a different climate to show the relative importance of watershed and climate parameters.


How Accurate is the Hydrology?How Accurate is the Hydrology?

Two methods for estimating discharge:Two methods for estimating discharge:

1.1.Regression (compare with similar stream).Regression (compare with similar stream).

2.2.Hydrology model (use topo and weather).Hydrology model (use topo and weather).

Hydrology of Ungaged StreamsHydrology of Ungaged Streams


Dimensionless Daily Discharge in cubic meters per second

Ungaged = 0.9821*Gaged + 0.0179Correlation Coef. = 0.9313

0.00

2.00

4.00

6.00

8.00

0.00 2.00 4.00 6.00 8.00Gaged River

Un

gag

ed


Regression analysis method based on assumed similar stream

0

1

2

3

4

5

6

7

8

1 21 41 61 81 101 121 141 161 181 201 221 241 261 281 301 321 341 361

Day of Year

Dis

char

ge/

Ave

rag

e

Actual

Estimated

How accurate is the estimated energy

potential?


Streamflow Comparison: actual and estimated

Hydrology of Ungaged StreamsHydrology of Ungaged Streams


How risky is the How risky is the investment?investment?

Energy production depends on how Energy production depends on how much of the streamflow will be used, much of the streamflow will be used,

and how much will be spilled.and how much will be spilled.

Energy from Ungauged StreamsEnergy from Ungauged Streams

Accuracy of the energy estimate Accuracy of the energy estimate depends on installed capacity.depends on installed capacity.



Ungaged Site: Errors in annual energy depend on developed capacity.

0

2

4

6

8

10

12

0.00 0.50 1.00 1.50 2.00 2.50 3.00

Average Annual Mw

Per

cen

t

Evaluate Risk.


Energy Comparison2 Mw Plant

0

500

1000

1500

2000

2500

1 21 41 61 81 101121141161181201221241261281301321341361

Day of the Year

KW

-Day

s

Estimated hydrology Measured

hydrology

Look into using the hydrologic model in IMPLook into using the hydrologic model in IMP

Optimizing Installed Capacity for Small Optimizing Installed Capacity for Small Hydro on Ungauged StreamsHydro on Ungauged Streams

Hydrology should not be “assumed”Hydrology should not be “assumed”

Hydrology is a basic requirement.Hydrology is a basic requirement.


The Integrated Method for PowerThe Integrated Method for Power

IMPIMP

IMP considers:IMP considers:

•Elevation rangesElevation ranges

•Topographic differencesTopographic differences

•Climate differences with locations and elevationClimate differences with locations and elevation

•Forest cover and soilsForest cover and soils


2.2. IMP flood frequency curve.IMP flood frequency curve.

• In addition to providing an estimate of the flood frequency curve the method in IMP provides an opportunity to gain understanding of the practical role played by approximations and guestimates.


Flood Frequency – snow and rain contributionsFlood Frequency – snow and rain contributions

RainSnow

Combined

Observed

3.3. The Power Study ModelThe Power Study Model

• Selection of the penstock-turbine-generator set that best suits the site. Develop the data for a trade-off curve between reservoir capacity and costs, and generating capacity and costs. The model shows the relationship between energy output and the penstock capacity and identifies the maximum energy that can be developed from a given penstock diameter and material.

Optimized installed capacityOptimized installed capacity

Optimum capacity = 16 MW

Marginal cost = marginal benefit

4.4. Instream Habitat for FishInstream Habitat for Fish

• Gain an understanding of how new hydraulic conditions can simultaneously degrade and improve habitat, depending on species and life stage, and the hydrograph.

Channel shape affects habitat potentialChannel shape affects habitat potential

Species & life stage of fish determines habitat requirementsSpecies & life stage of fish determines habitat requirements

Combination of fish and channel shape determine Combination of fish and channel shape determine how discharge affects habitat.how discharge affects habitat.

power canal

Reduced flow in bypass reach affects fish

Canal intakes

Near Kunming, SW China

canal

Stream discharge changes determine habitat impactStream discharge changes determine habitat impact

Discharge

Habitat area

Date

Hydrology ConsiderationsHydrology Considerations


•Development of the flood frequency curve.

•Matching the penstock-turbine-generator set.

•Calculation of the energy capability.

•Economic optimisation of installed capacity.

•Assess impact of development on instream habitat

•The time series hydrograph: often unknown flows.

Thank you for listening.Thank you for listening.

Small hydro sites hydrology: Small hydro sites hydrology: Optimum capacity screening and Optimum capacity screening and

estimation of fish habitat estimation of fish habitat requirements.requirements.

Charles D. D. HowardCharles D. D. HowardSenior Advisor Senior Advisor

Charles Howard & Associates LimitedCharles Howard & Associates Limited

www.cddhoward.comwww.cddhoward.com

Documents

Small hydro sites hydrology: Optimum capacity screening and estimation of fish habitat requirements. Charles D. D. Howard Senior Advisor Charles Howard