water harvesting + recharge · e.g. for an extra x usd we add 2 tube wells to your borehole e.g....

WATER HARVESTING +

RECHARGE:

Roads for Water &

Sponge Cities

BY LUWIEKE BOSMA– LBOSMA@METAMETA.NL

Smart Centre Symposium Mzuzu

Outline

▪ 1. Water harvesting and buffering

▪ 2. Roads for Water

▪ 3. Sponge Cities

▪ 4. Smart Centre integration

The principles of Retention, Recharge and Re-use

1. Water Harvesting and buffering

(Rockstrom et

al. 2007)

Rainfall partitioning

(Source: Mahler)

Water Harvesting

▪ Water Harvesting (WH) refers to the collection of

rainfall for multiple uses, either stored in the soil

profile for immediate uptake by the crop or stored

in a reservoir for future (multiple) uses.

Why doing it?

In arid lands:

• Strong seasonality of precipitation

• Quick runoff and seasonal rivers, dominated by flash floods

• High evaporation rates

• Climate change may result in more extremes

• Potentially the amount of rainwater can meet most of environmental and human needs

• Enormous potential to keep water in the system?

Delft Kitui

Compare for instance Delft (Netherlands)

with Kitui (Kenya)

Why doing it?

In humid zones:

• Dry spells in the dry season

• Risks of erosion and flooding increase

• When more agricultural production takes place on (esp. on

slopes)

• Due to increase of population (e.g. more paved surface)

• Climate change extremes

• Waterborne diseases in surface water can be

prevented if there is a more stable groundwater

table

- The holes need to be closed

(Retention)

- Filling of the bucket must be improved

(Recharge)

- The use of water must be improved

(Reuse)

The water buffer is like an old bucket…3

R A

ctio

ns

What is water buffer management?

▪ Ensure better storage of water in the

landscape; as shallow groundwater, as soil

moisture or in local surface reservoirs:

▪ Multiple sources for multiple uses

▪ Often there is enough rainfall, but not enough

storage

3R Recharge – Retention - Reuse

1. Recharge adds water to the buffer and as such it adds water to the circulation: infiltration of rain and runoff water

2. Retain water in the system: In situ retention slows down the lateral flow of groundwater. This helps pond up groundwater and creates large ‘wet’ buffers. Makes water circulation easier.

3. Reuse the water and make it revolve. Not only reduce the usage, but also ensure circulation. Drainage and waste water is a resource.

3R Retention

Kitchen garden

Bio-digestor

3R in practice

▪ Many technologies available and to be chosen

according to local context and needs;

▪ Many small, cheap measures spread at high

density all over the landscape;

Using roads in a beneficial way for water

harvesting and management

2. Road Water Harvesting

Dream and opportunity

To have roads systematically used for water

recharge/retention, storage and water

management all over the world, especially in Sub

Saharan Africa and Asia and create win-wins

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Why roads?

▪ Annual investment 1-2 Trillion USD

▪ 40% in developing countries

▪ 1 Billion people totally unconnected

▪ Increased water stress – most poor in water stressed

areas (74%)

▪ &

▪ Annual increase of roads: f.i. 70,000 km in SSA

▪ Water is 35% of damage to paved roads, up to 80%

to unpaved roads

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Why roads?

▪ now often causing local flooding, water logging

and erosion

➢ This can be turned around in large potential for

water harvesting and water management

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▪ Roads alter surface hydrology

▪ Changed runoff patterns

▪ Roads affect movement of shallow

groundwater

▪ Degradation of watersheds happens

in many parts of the world

Urgent need to turn things around

Floods

Erosion

Esp feeder roads damaged

Sedimentation

Triple Win

REDUCED WATER

DAMAGE

TO ROADS

(-35%, -80%)

And more reliable

Roads

WATER MANAGED

FOR PRODUCTIVE USE

Rising groundwater levels

and better soil moisture

Water retention

Erosion control

Flood management

REDUCED

DAMAGE FROM ROADS

Through Flooding,

Erosion and Sediment

Deposition

Turning things around: Harvesting water from

roads in Ethiopia – example of impact

▪ Capturing rainfall for dry periodas groundwater, soil moisture or surface water

▪ Implemented since 2014

▪ Withstanding 2015 El Nino

▪ Engaged> 2.75 M people in 2015/7 campaigns

▪ Benefitted 2.4 M people

▪ Guidelines

▪ Outscaling now to Bangladesh, Kenya, Uganda, Malawi, Mozambique, Tajikistan, Zambia, Nepal, Bolivia

Three Approaches

1. Making use of the road as it is for water

management - adaptation

2. Modify and optimize design of the road

3. Additional measures & opportunities

Road water management technique Surface

storage

Soil

moisture

storage

Shallow

groundwater

recharge

1 Flood water spreaders along road

surfaces

2 Flood diversions from culverts and road

drainage

3 Infiltration structures fed from road

drainage

4 Cascading irrigation from road drainage

5 Surface storage fed from road drainage

(borrow pits, ponds and cisterns)

6 Road bodies used as dams

7 Road crossings used as sand dams or as

water spreading structures

Principles of road water harvesting

design

▪ ‘give’ the runoff back to the land / farms

▪ Diversions + spreading to nearby farmland

▪ Prevent rapid draining of water from the watershed

▪ Prevent flood peaks

▪ Rather have the runoff water run in to vegetation

bunds and farm fields or pastures – will also reduce

sediment deposition

▪ Examples from different countries

ETHIOPIA: ROAD WATER HARVESTING CAMPAIGN

ETHIOPIA: CATCHMENT APPROACH

Deep trenches

Culverts

Borrow pit

Communities which used to have been affected

by flooding are saved from flooding.

Uganda: managing rice field with roads

MANY COUNTRIES, CONTEXTS AND SOLUTIONS

Mozambique: low embankment

roads to manage wetlands

Uganda: managing rice cultivation with

roads embankments and culvert

Zambia: Converting borrow pits

Kenya: Road drifts as sand dams

BANGLADESH: USING ROADS AS EFFECTIVE EMBANKMENTS

Synchronized levels

Roads as embankments

Flood shelters

Better protection

KENYA: ROAD RUNOFF COLLECTED IN STORAGE STRUCTURES

Converted borrow-pit

for water storage

On farm pond

collecting road runoff

Opportunity: Road water for wildlife

KENYA: USING CUTOFF TRENCHES TO TAP ROAD RUNOFF

Cutoff from side drain

Excess water redirected

Stored in a trench to

increase soil moisture for

agricultural production

KENYA: USING CULVERTS & DRIFTS

Cross-culvert used to harvest water in a trench

Collecting water from a culvert

Soaking pits along the road for groundwater recharge

and increased soil moisture

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Trenches/Soaking pits for groundwater

recharge and increased soil moisture

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Integrated watershed management

1549630 ha

Diversion from culvert outlet

Many additional opportunities to better use

roads for water

1. Controlled sand mining along roads

2. Evacuation in times of floods

3. Road side tree planting

4. Brick making

5. Biological rodent control

6. Intermediate means of transport

>> We can turn roads into development reservoirs

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Road side tree

planting

Brick making – using runoff sediments

Cost Benefit Analysis

Kitui representative of 8 sub-counties (30

farms)

Mbitini (ward in Kitui County) (60

farms)

Costs: 2440 KSH

Benefits: 7273 KSH

The costs of construction compared with the return on investment after 1

growing season

Beyond techniques, it’s about Governance

▪ 1. Integrate within Programs on Roads and Water and Agriculture

▪ 2. Community engagement

▪ 3. Change procedures in roads development• Manuals

• Investment and maintenance budgets

• Cooperation

▪ 4. Capacity building• Technical training – county staff and road engineers

• Short courses

• Tools (run-off models)

• Guided learning

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For example: Kenya: working as partners with

County Governments and Road Authorities

▪ Technical team in Kitui, Makueni & Machakos

▪ Cross-sectoral coordination and integration

▪ For all activities within the County

▪ Departments of Water, Agriculture, Roads &

Coordination

▪ Representatives of ASDSP and KeRRA

▪ Ongoing links with road Authorities to integrate in

their projects and guidelines

Can we make a water buffer in an urban

environment

3. Sponge Cities

Collecting water from

rooftops

Bridge across seasonal

stream to check and store

seasonal floods Using stormwater for

groundwater recharge

Porous paving for

increased infiltration

Sponge City

▪ Innovative designs are piloted on the base of

detailed research.

▪ The implementation of multiple techniques can be

combined, making up an integrated approach for

storm water management

▪ A guideline on how-to plan sponge towns will be

developed together with the Kajiado sponge city

team and with relevant authorities.

It is about

▪ Creating a buffer – protect and store during rains

& release slowly when it is dry

▪ Diversified supply for multiple uses

▪ Support self-supply

▪ Supporting business and government initiatives

▪ Work with citizen platforms and private households

▪ Skill building of local masons and artisans

Spong city in practice

Focused on 6 techniques:

▪ Roof harvesting systems

▪ Gully plugging – check dams

▪ Ponds for water storage and farming

▪ Kitchen gardening + grey water reuse

▪ Tree planting

▪ Road water harvesting

Kajiado: groundwater recharge

Integrating water harvesting into Smart Centre

technologies and approach

4. Smart centre integration

SC meets RfW and Sponge

Benefits water harvesting & buffering for Smart Centres:

▪ Increase the natural buffer

▪ Make the technologies last longer

▪ E.g. with infiltration pits for recharge the water level in a well/borehole will be higher and more reliable over time

▪ Cost reduction for maintenance?

▪ Opportunity to be involved in practical training on 3R methods, RfW and Sponge?

What could work well?

Make water harvesting part of the package?

▪ Interesting business-model?

▪ E.g. for an extra X USD we add 2 tube wells to your borehole

▪ E.g. for an extra X USD we add a training on water retention and

recharge

▪ E.g. for an extra X USD we will advise on implementing diversions

▪ Provide it as an add-on, e.g. different packages with or

without water harvesting indicating possible life-spans and

costs in the longer term? Provide CBA

▪ Also provide interventions for Roads for Water and Sponge

Cities as stand alone?

How do RfW and Sponge contribute?

▪ Share expertise on road water harvesting and

Sponge Cities

▪ Linkages to farmers, organizations and government

sector interested

▪ Up-scaling and creating more business opportunities

▪ Lobbying and support for resource mobilization

Room for discussion

▪ How can Smart Centre technologies and its

approach also support water harvesting initiatives?

▪ How do you see the business-model of the wider

package that includes water harvesting – is there

interest for this?

▪ Could we have a pool of technicians on water

harvesting specifically?

▪ How to market this opportunity?

▪ Suggestions?

Thank you!