/ES2_Mazzoli

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

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The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

General catchment characteristics • 600 km2 wide • Elevations ranging from approximately 1400 m asl to 0 m asl.

• Precipitation ranges from 700 to 1100 mm/y on average,( from the coast to the Apennines divide. )

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

General catchment characteristics Flow duration curve assessments

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Main channel characteristics

wide gravel bed where braided sub-channels form and evolve continuously gravel has been extracted in large quantities (stopped in 1980)

•

Channel erosion (Canyon)

•

hydrogeological risks due to the presence of infrastructures

•

reduced the solid discharges to the coast

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Area of interest Direction of regressive scour

Flow direction

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Position of the problem Drop of approximately 15 m in the plain( natural channel slope is already of the order of 0.1 – 1 %. )

regressive scour Rapidly evolved in the last 15 years 1990-2004

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Position of the problem 41

XSection 42

42

1990 2004 XSection 41

10 m

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Water diversion as a tool for channel stabilization

diverting a significant part of the flows

HYDROPOWER PRODUCTION

reducing transport capacity of the stream AND the scouring pace over extended time periods

maximise effects of transport capacity reduction AND good profitability of energy production

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Hydraulic –Transport modeling

natural flow duration curve

hydraulic – transport model of the river

modifications according to different withdrawal hypotheses quasi-2D hydraulic model (HEC-RAS) wide combination of approaches for the estimation of sediment transport capacity

optimal withdrawal potentiality of approximately 8 m3/s The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Hydraulic – Transport modeling marecchia_river

Plan: Plan 18

28/09/2005 marecchia_river

.04

. .03 0 3 5

105

.1

Plan: Plan 17

20/09/2005

.04 .04

Legend

.07

.04 .03

.07

.1

.04

130

Legend

Ground Ground

Bank Sta

Bank Sta

100

120

90

Elevation (m)

Elevation (m)

95

110

85

80

100

75

90

70

0

200

400

600

800

1000

1200

0

200

400

600

800

1000

Station (m)

Station (m)

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

1200

Hydraulic – Transport modeling Transport in suspension

Transport at the channel bottom

Meyer-Peter e Mueller (1948)

Smith e McLean (1977)

Ashida e Michiue (1972)

Van Rijn (1984)

Engelund e Fredsoe (1976, 1982)

Garcia e Parker (1991)

Van Rijn (1984) Parker (1991)

•D50 =0.1 mm mean representative diameter

•Different withdrawals hypothesis

Flow shear stress duration curves –Transport capacity The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Hydraulic – Transport modeling 50 2] τ [N/m 45

Shear stress τ =N/m2

Flow shear stress duration curves

40

35 ante Qder=1

30

Qder=3

Ante operam condition

Qder=5

25

Qder=8

Different derived discharge

Qder=10 Qder=15

20

15

10

5

0 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Q

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

100%

Hydraulic – Transport modeling 60%

% reduction in transport capacity on the yearly basis for bottom and suspended transport

50%

40%

bottom rid sosp suspend

Design discharge of 7.4 m3/s

rid fondo

30%

20%

10%

Qder ranging from 1 to 15 m3/s 0% 0

2

4

6

8

10

12

14 Q der [m3/s] 16

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Evaluation of Hydropower development feasibility • Total hydraulic drop 20 m • Kaplan turbine (maximum discharge of 7.4 m3/s) •Annual average discharge 3.7 m3/s •Minimum ecological flow 0.7 m3/s •Annual discharge to turbines 92 Mm3/y

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Evaluation of Hydropower development feasibility

•Mean annual energy production 3369 MWh •CO2 equivalents 1955 t/y •Investment Pay back period under 3 years •Internal rate of return (IRR) = 39.6 % •Net Present Value (NPV) over 30 yrs of about 1,700,000 Eur (public incentive to small hydropower plants )

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Evaluation of Hydropower development feasibility

Discharge withdrawal

and Riverine habitat modification ???

•Withdrawal affects only a short stretch of the river, approximately 1000 m • The stretch under consideration is already virtually impermeable to fish migration

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

Conclusions Carefully designed small hydropower plant can be thought of as a multi-objective tool for river management

water withdrawal as a means of scour control

profitability of the plant allows to envisage hydropower development as a strategy to generate funding for river restoration besides

coupling the hydrologic, hydraulic and ecologic understanding of rivers with clean energy production may enhance our capabilities to detect situations where hydropower development is not only sustainable, but also helps a general management of river systems.

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development

www.gecosistema.it

The Marecchia jump power project: coupling hydrogeologic hazard mitigation with hydropower development