Green Water Credits

Use of quantitative tools to evaluate potentialGreen Water Credits options

Peter DroogersWilco Terink

Johannes HuninkSjef Kauffman

Godert van Lynden

Blue and Green Water

Example of potential benefits

Introduction

CONCEPTS BIOPHYSICAL ANALYSIS

Tools and Information

Understand current water resources

Understand past water resources

Options for future- technical- socio-economic- policy oriented

TrendPast

Today

Future

• Observations• Remote Sensing• Analysis • Statistics

• Models?change

Quantification GWC

Water Demand?

Water Consumption?

Water Supply?

Impact Changes?

Productive Use?

Soil Water Conservation impact?

GWC Proof

• Observations in field (flows, erosion)– Precipitation dominant factor

• Large scale– experimental plots not possible

• Simulation model– experimental basin in PC– multiple options can be tested– various weather conditions (dry-wet)

Tool Selection

Physical detaillowhigh

Sp

atia

l sc

ale

field

system

basin

continentPodium

STREAM

SLURP

WSBM

SWAT

WEAP

IQQM

SWAP

AquaCrop

SWAT and WEAP

SWAT(Soil and Water Assessment Tool)

• Supply analysis

• Physical Based

• Impact soil-water-conservation measures

• Detailed farm management analysis

• Public domain• User friendly interface

WEAP(Water Evaluation And Planning systems)

• Demand analysis

• Conceptual based

• Benefit – Costs analysis

• Detailed upstream-downstream interactions

• Public domain• Very user friendly interface

RIVER BASIN SOIL AND WATER CONSERVATION

Methodology

• Hydrological models as a tool to simulate the paths of water and soil movement

• Upstream-downstream interactions

Methodology

• Soil and Water Assessment Tool (SWAT)

• Physically based• Focus on water-erosion-land

management processes• Public domain• Large user-group worldwide• Successfully applied in many

other studies worldwide as well as in Kenya

Data

• Data sets required:– Digital Elevation Model (DEM)– Climate– Land use and management– Soils– Streamflow– Reservoirs

Data Sources

locally-sourced

non-RS

globalpublic-domain

RemoteSensing

Land Cover

StreamflowOperations

Climate

LAI

Soils

Topography

Socio-Economic

Groundwater

Data

Elevation

Landuse

SoilsClimate

Model Reliability

Selection of GWC options

• 11 options explored• Bench terraces• Conservation tillage • Contour tillage• Fanya Juu terraces• Grass strips• Micro-catchments for planting fruit trees• Mulching• Rangelands• Ridging • Riverine protection• Trash lines

• Labor: intensive vs. extensive• Investment: low vs. high• Implementation on 20% of area ~ 100,000 farmers

Results: Key Indicators

• Upstream– Crop transpiration– Soil evaporation– Groundwater recharge– Erosion

• Downstream– Inflow Masinga– Sediment load Masinga

• Climate– dry (2005)– wet (2006)

Results: Key Indicators

Inflow Masi

nga

Sedim

ent inflow M

asinga

Crop tr

ansp

iration

Soil e

vaporation

Groundwate

r rech

arge

Erosio

n

Scenario Land use* Year MCM/y Mton/y mm/y** mm/y** mm/y*** ton/ha/y***

dry 931 1.0 335 121 16 1.2

wet 2508 4.2 308 140 128 7.9

dry 1.1% -21% 0% -1% 3% -23%

wet 1.9% -21% 0% 0% 2% -18%

dry 0.1% -1% 1% -5% 1% -2%

wet 0.1% -1% 1% -4% 0% -1%

dry 1.1% -10% 0% -1% 7% -12%

wet 0.8% -7% 0% 0% 3% -6%

dry 0.4% -21% 1% -1% 4% -23%

wet 1.3% -20% 1% 0% 2% -18%

dry 0.6% -11% 0% -1% 3% -14%

wet 0.6% -10% 0% 0% 1% -10%

dry 0.6% -8% 0% -1% 2% -8%

wet 0.6% -6% 0% 0% 1% -5%

dry 0.4% -6% 3% -12% 3% -9%

wet 0.5% -6% 2% -12% 2% -8%

dry 0.1% -4% 0% -3% 1% -4%

wet 0.0% -2% 0% -2% 0% -6%

dry 1.4% -18% 0% -1% 23% -21%

wet 1.0% -12% 0% -1% 10% -12%

dry 0.0% -5% 0% -1% 0% -5%

wet 0.0% -4% 0% 0% 0% -4%

dry 0.6% -7% 0% -3% 3% -8%

wet 0.6% -6% 1% -2% 1% -5%

*M=Maize, C=Coffee, T=Tea,A=Agricul tura l ASAL, R=Rangelands ;

** Agricul tura l areas ; *** Bas in-wide;

Baseline

Inflow Masi

nga

Sedim

ent inflow M

asinga

Crop tr

ansp

iration

Soil e

vaporation

Groundwate

r rech

arge

Erosio

n

Scenario Land use* Year MCM/y Mton/y mm/y** mm/y** mm/y*** ton/ha/y***

dry 931 1.0 335 121 16 1.2

wet 2508 4.2 308 140 128 7.9

dry 1.1% -21% 0% -1% 3% -23%

wet 1.9% -21% 0% 0% 2% -18%

dry 0.1% -1% 1% -5% 1% -2%

wet 0.1% -1% 1% -4% 0% -1%

dry 1.1% -10% 0% -1% 7% -12%

wet 0.8% -7% 0% 0% 3% -6%

dry 0.4% -21% 1% -1% 4% -23%

wet 1.3% -20% 1% 0% 2% -18%

dry 0.6% -11% 0% -1% 3% -14%

wet 0.6% -10% 0% 0% 1% -10%

dry 0.6% -8% 0% -1% 2% -8%

wet 0.6% -6% 0% 0% 1% -5%

dry 0.4% -6% 3% -12% 3% -9%

wet 0.5% -6% 2% -12% 2% -8%

dry 0.1% -4% 0% -3% 1% -4%

wet 0.0% -2% 0% -2% 0% -6%

dry 1.4% -18% 0% -1% 23% -21%

wet 1.0% -12% 0% -1% 10% -12%

dry 0.0% -5% 0% -1% 0% -5%

wet 0.0% -4% 0% 0% 0% -4%

dry 0.6% -7% 0% -3% 3% -8%

wet 0.6% -6% 1% -2% 1% -5%

*M=Maize, C=Coffee, T=Tea,A=Agricul tura l ASAL, R=Rangelands ;

** Agricul tura l areas ; *** Bas in-wide;

11 Trash lines

Baseline

1 Bench terraces

2 Conservation tillage

3 Contour tillage

4 Fanya Juu terraces and variations

5 Grass strips

6 Micro-catchments for planting fruit trees

7 Mulching

8 Rangelands

9 Ridging

10 Riverine protection

MCT

M

M

MCT

MCT

MCT

MCT

MCT

AR

M

MCTA

Results: Spatial

OVERALL BENEFIT-COST ANALYSIS

WEAP Tool

• Impact of changes in water-soil dynamics on:– upstream

• rainfed improved production– downstream

• hydropower• domestic water supply• irrigation

• Benefit-cost analysis

• Integrations tool: WEAP

WEAP Tool

WEAP: Validation

Masinga Inflow

Masinga Outflow

Kamburu Outflow

Gitaru Inflow

Kindaruma Outflow

Kiambere Outflow

Results: Reduction in water shortage

00_Base 01_Bench 02_ConsTill 03_ContTill 04_FanyaJuu 05_GrassStrips 06_MicroCatchments 07_Mulching 08_Rangelands 09_Ridging 10_Riverine 11_TrashLines

Unmet DemandAll Demand Sites (13), All months (12)

2005

Milli

on C

ubic

Met

er

0.0

-0.5

-1.0

-1.5

-2.0

-2.5

-3.0

-3.5

-4.0

-4.5

-5.0

-5.5

-6.0

-6.5

-7.0

Results: Increase in hydropower

00_Base 01_Bench 02_ConsTill 03_ContTill 04_FanyaJuu 05_GrassStrips 06_MicroCatchments 07_Mulching 08_Rangelands 09_Ridging 10_Riverine 11_TrashLines

Hydropow er GenerationAll Reservoirs (9), All months (12)

2005

Tho

usan

d G

igaj

oule

180

160

140

120

100

80

60

40

20

0

Results: Increase in Benefits

Results: Benefit-Cost Analysis

• 20% of area ~ 100,000 smallholders

Benefits Costs mUS$/y ha 01_Bench 9.9 92,865 02_ConsTill 1.0 52,766 03_ContTill 4.9 52,766 04_FanyaJuu 9.0 92,865 05_GrassStrips 5.3 92,865 06_MicroCatch 1.6 1,000 07_Mulching 5.1 92,865 08_Rangelands 0.8 136,916 09_Ridging 8.9 52,766 10_Riverine 2.0 10,000 11_TrashLines 3.4 92,865

Costs Construction Maintenance

ha US$/ha US$/ha /y mUS$/y 92,865 100 20 2.8 52,766 0 0 0.0 52,766 0 0 0.0 92,865 200 20 3.7 92,865 50 20 2.3 1,000 500 20 0.1

92,865 0 0 0.0 136,916 50 0 0.7 52,766 100 20 1.6 10,000 100 20 0.3 92,865 50 20 2.3

B/C

mUS$/y mUS$ 2.8 7.1 0.0 1.0 0.0 4.9 3.7 5.3 2.3 3.0 0.1 1.5 0.0 5.1 0.7 0.1 1.6 7.3 0.3 1.7 2.3 1.1

DISCUSSIONS, CONCLUSIONS

Conclusions

• GWC beneficial for:– upstream– downstream

• Analysis tools:– SWAT: (upstream) supply– WEAP: (downstream) demand

• Steps– Understand current situation– Explore options

• GWC– Biophysical component– Socio-economics– Institutional– Financial

Discussion / conclusions

• Smaller focus area– current study: 1.8 million ha total; 0.5 million ha rainfed

• Definition of GWC options– effectiveness of implementation

• Convincingness of current approach– Rainfed farmers– Downstream beneficiaries

• Monitoring system

THANK YOU