experimental drought early warning system in the inner...

Experimental drought early warning system in the Inner Niger Delta

2013 International SWAT Conference, Toulouse, France

Samuel Fournet1,2, Stefan Liersch1, Valentin Aich1, Léo Zwarts4, Bakary Koné3, Fred F. Hattermann1

1 Potsdam Institute for Climate Impact Research

2 UMR G-eau, Montpellier Supagro

3 Wetlands International

4 Altenburg & Wymenga

Wednesday 17th of July 2013

Impacts of climate change and upstream river management on the flood regime in the Inner Niger Delta Outline

1. The Inner Niger Delta: case study characteristics

2. SWIM setup, development and calibration

3. Climate change and upstream water management scenario

4. Hydrological change and trends

5. Integration of the results in an operationnal drought early warning system in the Inner Niger Delta

2

Case study introduction Inner Niger Delta

3,27 M inhabitants

Large wetland inundation

plain (40.000 km²) in the

Sahelian climate zone

Drastic seasonal and

inter-annual variation in

discharge (30 to 50 hm3/y),

flood extent (5 to 25.000 km²)

Flood peak delay ~2 months

30 to 50% water losses

Zone crucial for fishing,

livestock, agriculture in

free submersion and the

biodiversity

High vulnerability from

upstream management

Source: http://earthobservatory.nasa.gov/ Zwarts et al., 2005, Niger the lifeline, Wetlands International

Pre-processing in the delta floodplain: upstream of each sub-basin´s outlets, inundated area and the water volume accumulated and trapped in ponds are identified into sequential layers

SWIM Soil and Water Integrated Model Development of Inundation module

Processes

1. Flooding

2. Routing, backwater

3. Evaporation (water surface)

4. Percolation

5. Release

Parameters

> Flooding: flow-threshold

> Flood release (linear)

1 2 5

Source: Liersch et al., 2011, SWAT conference

SWIM setup (1) Topography, Land-use, Soil, Sub-basins

5

Digital Elevation Model

Land-use classification

Soil classification and parameterization

Sub-basin delineation

Shuttle Radar Topographical Mission

SRTM Version 4, 90m resolution

Global Land Cover 2000 GLC

FAO Digital Soil Map of the World

Harmonized World Soil Database

Number of sub-basins: 1923

Sub-basin average area: 1150km²

Hydrotope

Hydrological

Response

Unit

SWIM setup (2) Climate inputs

Watch Forcing Data (WFD)

6 Source; Weedon et al., 2010 , Watch tech report 22 Aich and Fournet 2013 in Dewfora D4.6, PIK

• ECMWF

reanalysis ERA40

• from 1960-2001 at

daily time step

• 0.5° resolution

• Bias corrected

with Global

Precipitation

Climatology

Centre (GPCC v4)

and Climate

Research Unit

(CRU TS2.1)

7 Calibration Koulikoro gauge

SWIM calibration Discharge Global Runoff Data Centre (GRDC)

4

1 2

6 10

11

13

3 5

9

8

ID Monitored Gauge Calibration period NSE

1 Koulikoro 1964-1974 0.93

2 Douna 1964-1974 0.88

3 Ibi 1975-1995 0.87

4 Kouroussa 1964-1974 0.86

5 Lokoja 1972-1982 0.85

6 Dire 1964-1974 0.83

7 Kirango Aval 1975-1981 0.82

8 Kandadji 1976-1986 0.82

9 Selingue 1965-1975 0.8

10 Ansongo 1968-1979 0.76

11 Niamey 1975-1985 0.76

12 Tossaye 1968-1979 0.75

13 Malanville 1976-1986 0.54

14 Yidere Bode 1985-1995 0.18

7

14

Source; Aich and Fournet, 2013 in Dewfora D4.6, PIK

Climate change projections Air temperature trends in the Upper Niger Basin

8

4 Earth System Models (ESMs) Downscaled and bias corrected by Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP)

Use of 2 Representative Concentration Pathways underlying assumptions about radiative forcing

•GFDL-ESM2M (GFDL) •HadGEM2-ES (Had)

• IPSL-5 CM5A-LR (IPSL) • NorESM1-M (Nor)

•2.6 - “moderate” • 8.5 - “extreme”

Source; Liersch et al., 2013, AFROMAISON internal report, PIK

Climate change projections Precipitation trends in the Upper Niger Basin

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•GFDL-ESM2M (GFDL) •HadGEM2-ES (Had)

• IPSL-5 CM5A-LR (IPSL) • NorESM1-M (Nor)

•2.6 - “moderate” • 8.5 - “extreme”

4 Earth System Models (ESMs) Downscaled and bias corrected by Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP)

Use of 2 Representative Concentration Pathways underlying assumptions about radiative forcing


Upstream river management Reservoirs and Irrigation schemes

10

1. Current and future irrigation water uptake with restricted minimal flows were setup

in line with the development plan of the Niger Basin Authority and the future dams

in line with engineering technical report.

2. The scenario matrix was defined with local stakeholder representatives from the IND

region


Results: climate change projections Impact on discharge at the combined IND´s inlet

11

Results: river management scenario Impact on annual maximum inundated area

12

3 dams Irrig.

Ef.high

Irrig.

Ef. Med.

3 dams +

Irrig. Ef. High

Irrig.

Ef. Low


13 Source; Liersch et al., 2013, AFROMAISON internal report, PIK

Results: Scenario 3 dams + irrigation (Markala: 250.000) Impact on discharge at the IND´s oultet

Conclusion Summary and planned research

• Climate change projections: increase of interrannual variability but trend agreement on flow in/de-crease remain unclear

1 >> Use RCMs projection from CORDEX project to enlarge the spectrum and the state of art for regional climate change impact

• Upstream water management: results shows clear gradual impact on the flood propagation and extent

2 >> Test the impacts with other managerial options for dams

3 >> Vulnerability assessment of flood-dependent water uses

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Range of early warning signals in use for the annual flood peak in Mopti

15

Annual flood peak

water level

Annual flood peak

water timing

Classes Range Freq. Range Freq. Classes Range Freq. Range Freq.

Really low (80´s to 00´s) 440-550 cm. 10 330-410 cm. 10 Really early (70´s to 00´s) before 9 Oct. 11 in Oct. 10

Low (70´s to 00´s) 551-590 cm. 9 411-450 cm. 11 Early (70´s to 00´s) 9 to 16 Oct. 10 1 to 9 Nov. 10

Normal (70´s to 00´s) 591-640 cm. 11 451-500 cm. 9 Normal (70´s to 00´s) 17 to 24 Oct. 11 10 to 19 Nov. 12

High (80´s) 641-680 cm. 10 501-550 cm. 10 Late (80´s) 24 to 31 Oct. 8 20 Nov. to 30 Dec. 8

Really high (50´s to 60 ´s) 681-730 cm. 12 551-625 cm. 12 Really late (50´s to 60 ´s) in Nov. 12 in Dec. 12

Mopti Akka Mopti Akka

Source: Fournet , 2013 in Dewfora D4.8, PIK Koné Bakary, Wetlands International

OPIDIN stakeholder platform: dissemination via key persons, radio, bulletin

Workshop with sheperds to interprate and disseminate the results of OPIDIN prediction

Tool to predict flood peak and retreat water level and timing based on statistical regression function from historical water level time series

Conclusion Dissemination with OPIDIN Drought early warning system

Thank you for your attention !

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17

Questions ?

Spare slides

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Case study introduction Niger river

3rd longest river in

Africa watercourse 4200km

9th biggest fluvial

system area 2.1M.km2

~ 25% located in Mali

9 countries Benin, Burkina

Faso, Cameroon, Chad, Ivory

Coast, Guinea, Mali, Niger and

Nigeria

Major cities Tembakounda,

Bamako, Timbuktu, Niamey,

Lokoja, Onitsha

4 climate zones

• Humid tropical zone

• Tropical zone with dry seasons

• Sahelian zone

• Desert zone

UNEP. 2010 , Africa Water Atlas Zwarts et al., 2005, Niger the lifeline, Wetlands International

Case study introduction Upstream river basin management

The Upper Niger 2,43 M. inhabitants

• Covers the Guinean part of

the basin and stretchs to

Selingué dam included.

• Crucial for the generation of

water ressources with the

Fouta Djallon mountains

• Regulation and storage

infrastructure with Selingué

and the future Fomi dams

• 5 RAMSAR sites

The zone of the Offices 1.44 M. inhabitants

• Intensive irrigated rice

production with Office du

Niger (Markala dam), Office

de Ségou and Office de

Baguinéda with a high

potential to extend

agricultural area

• Bamako and the

hydropower dam of Sotuba

• High potential for navigation

The Bani catchment 0.53 M inhabitants

• Reservoir of Talo and

Djenné (planned

extension)

• High potential of rural

development of more than

100.000 ha (agriculture,

fishing and livestock)

• Projects of minor dams in

Baoulé, Gbado and

Bagoué

Source: NBA, PADD, 2010

Scenario matrix Reservoirs and Irrigation schemes

21

3. The scenario matrix was defined with local stakeholder

representatives from the IND region

Irrigation Scheme in ha Rice Rice CS Gardening Sugar CaneIrrigation Efficiency

m³/ha/y

Provision

in l/ha/s

Sélingué 1600 31000 1.5

Baguinéda 3000 400 71500 2.2

Markala (ON) 77000 7700 15400 5000 30000 [SC:71200] 2.7 [SC:3.4]

Sélingué planned 3200 31000 1.5

Djenné planned 68000 13276 2.4

Talo planned 20000 13276 2.4

Fomi planned 3000 10000 11500 1

Markala ON extension 1) 220000 22000 44000 30000 13500 [SC:71200] 1.2 [SC:3.4]



1. Current and

future Irrigation water

uptake and efficiency

were setup in line with the

development plan of the

Niger Basin Authority and

the future dams in line with

engineering technical

report.

2. Water uptake

was restricted to minimal

flows (40m3/s at Markala

and 10m3/s at Fomi,

Sélingué, and Djenné)

SWIM Soil and Water Integrated Model

Process based eco-hydrological model, simulates runoff generation, nutrient and carbon cycling, plant growth and crop yield, river discharge and erosion as interrelated processes with a daily time step on the river basin scale

New Features

• Reservoir-model to simulate effects of reservoir management, including Hydropower production

• Conditionnal irrigation uptake in the river routing

• Inundation-model to simulate effects of wetlands (flood propagation, evapotranspiration and discharge from wetland area)

22 Source: Krysanova et al., 2000, SWIM manual, PIK report n°69

SWIM Soil and Water Integrated Model

23

groundwater flow Groundwater (shallow aquifer)

soil water

content

eva

pora

tion

relative humidity

wind speed

air temperature

net radiation

surface roughness

LAI

transpira

tion

passage time t

per layer

hydraulic

conductivity

field

capacity

saturated

conductivity

percolation

drainable water

from the saturated

zone

slope length

drainage porosity

subsurface drainage

retention

coefficient

surface drainage

land use

soil texture

management

slope

pre

cip

itatio

n

ca

pilla

ry ris

e

OPIDIN (Flood prediction tool for the Inner Niger Delta) Statistical tool

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Example of regression curves for annual peak flood water

level from Mopti to Mopti the 30th of September

Source: Zwarts Léo, 2009, A&W report 1254 Fournet , 2013 in Dewfora D4.8, PIK

Calibration (with WFD_ERA40) Scenario A Flood propagation in the IND: SWIM simulation vs. Remote sensing

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Results Scenario B Climate change impact on annual maximum inundated area

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experimental drought early warning system in the inner...

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