Sustainable Water Harvesting Practices

for dryland Restoration Mehreteab Tesfai

Norwegian Institute for Agricultural and Environmental Research, Norway

28-30 April 2015

COST ES1104 MC meeting in Thessaloniki, Greece

► Map of water scarcity areas: overview ► Water harvesting (WH): definitions and concepts ► WH practices for dryland restoration ► WH indicators and methods ► Prioritizing WH constraints and benefits ► some Remarks

Contents

Physi

cal w

ate

r sc

arc

ity r

efe

rs t

o s

ituati

ons

when

wate

r is

not

abundant

enough t

o m

eet

all d

em

ands

Econom

ic

wate

r sc

arc

ity

where

dem

and

for

wate

r is

not

sati

sfie

d because

of

lack of

invest

ment

in w

ate

r or

hum

an

capacit

y.

► Catchment area: part of the land that contributes some or all of its share of rainwater to another area, outside its boundaries.

► Storage facility: runoff water from the time it is collected until it is used.

► Target area: harvested water used for agriculture, drinking or domestic purposes.

Water Harvesting (WH) is defined as ‘the collection and management of rainwater or floodwater runoff to increase water availability for domestic and agricultural use as well as for ecosystem sustenance’ (Mekdaschi and Liniger, 2013).

Catchment

Storage

Target

Runoff

Rooftop WH

Floodwater WH

Macrocatchment WH

Microcatchment WH

Impacts Contributes to high medium low References (for e.g.)

water availability

provide water for irrigation

and drinking, recharges GW X Tesfai & Stroosnijder (2000)

biodiversity support biodiversity X Mekdaschi and Liniger (2013)

soils/dryland

restoration

build up arable soils and

reduce salinity X Tesfai & Sterk (2002)

socio-economic

increase crop yield by 50%,

enhance food security X Steenbergen etal (2010)

livelihood improve human well being X FAO (2010a)

Spate irrigation is a water diversion and

spreading technique that makes use of seasonal

floods for agricultural production. These floods

which spring from highland and mountainous

areas are diverted to irrigate adjacent land in the

arid lowlands, using diversion structures (Tesfai,

2001; FAO, 2010).

Flood water harvesting: Eritrea

6

Impacts Contributes to High

Medium

Low

References (for e.g.)

water

availability

increase water for drinking,

agriculture X FAO (2010b)

recharge GW table, aquifer X Mekdaschi and Liniger

(2013)

biodiversity increase vegetation, fish farming X Mekdaschi and Liniger

(2013)

soil/dryland

restoration

reduce downstream flooding,

erosion X HR Wallingford (2004)

socio-economic

imporve food security and

conservation knowledge X Mekdaschi and Liniger

(2013)

livelihood improve human well being X FAO (2010b)

Small earth dams: water harvesting storage structure constructed

across narrow sections of valleys to impound runoff generated from

upstream catchment areas (Mekdaschi and Liniger, 2013)

Macrocatchment water harvesting: dryland areas in the tropics

Furrow-enhanced runoff harvesting: used to grow olive trees

through annually constructed V-shaped earthen bunds (reinforced by

stones) constructed manually by hoe around each tree and enhanced

by downslope ploughing. The furrows then divert runoff to the

microcatchments where it concentrates in basins around the trees.

(Mekdaschi and Liniger 2013)

Impacts Contributes to High Medium Low References (for e.g.)

water availability save irrigation water X Mekdaschi and Liniger

(2013)

biodiversity stimulate olive tree growth X >> >> >>

soil/land

restoration

reduce surface runoff/soil loss X >> >> >>

enhance soil moisture storage X >> >> >>

increases soil fertility X >> >> >>

socio-economic improve conservation knowledge X >> >> >>

livelihood improve human well being no data

Microcatchment water harvesting: Syria

Zai Pit System: a soil rehabilitation system used to concentrate runoff

water and organic matter in small pits. The pit typically is 20-30 cm in

width, 10-20 cm deep and spaced 60-80 cm apart. A handful of organic

material (0.3 kg) such as manure, compost, or dry plant biomass is added

in the pit hole (Gandah et al., 2003; Tim et al., 2013). Impacts Contributes to High Medium Low References (for e.g.)

water availability improve water use efficiency X

Danjuma and Mohammed

(2015)

biodiversity increase crop diversification X Tim et al. (2013)

soil/dryland

restoration

increase soil moisture X Tim et al. (2013)

improve soil fertility X

Danjuma and Mohammed

(2015)

reduce soil erosion X

Danjuma and Mohammed

(2015)

socio-economic

double cereals yield and increase

farmers’ income X Amede et al. (2011)

livelihood improve human well being X Amede et al. (2011)

Microcatchment water harvesting: The Sahel (Burkina Faso, Mali, etc.)

Hillside Terracing to reduce soil erosion on steep hill slopes by constructing

soil/stone bunds across the slope reinforced with planting trees.

Tied ridges: type of surface configuration whereby the ridges are “tied” to each

other at regular intervals by cross-dams, blocking the furrow to collect rainwater

and prevent surface run-off on site (Biazin and Stroosnijder, 2010)

Impacts Contributes to High Medium Low References (For e.g.)

water availability increase water for plants X Biazin and Stroosnijder (2010)

biodiversity increase wood production for fuel X Mekdaschi, and Liniger (2013)

soil/dryland

restoration

increase soil moisture by 24% X McHugh et al. (2007)

reduce soil and nutrent losses X Mekdaschi and Liniger (2013)

socio-economic

increase household income X >> >> >>

Improve conservation knowledge X >> >> >>

mobilise community participation X >> >> >>

livelihood improve human well being X >> >> >>

Microcatchment water harvesting: Eastern Africa

Impacts Contributes to High Medium Low References (for e.g.)

water availability

increase water suppy for drinking and

irrigation X Mekdaschi, and

Liniger (2013)

soil/dryland

restoration increase soil mositure in home garden X Beckers et al.

(2013)

biodiversity

increase crop diversity around home

garden X Kahinda and

Taigbenu (2011)

socio-economic improve household food security X Helmreich and

Horn (2009)

livelihood improve human well being X Mekdaschi, and

Liniger (2013)

Roof top rainwater harvesting: a technique through which rain

water is captured from the roof catchments and stored in

reservoirs/tanks to improve household access to water for

drinking, sanitation and home garden irrigation (Kahinda and

Taigbenu, 2011).

Roof top rainwater harvesting: dry lands in the Tropics

Indicators Methods/approach References

catchment area (ha, km2) field mapping GIS-based Munyao (2010)

volume of water stored (soil profile, mm

reservoirs, m3) storage measurements HR Wallingford (2004)

target area (plant, animal, human) ha/no. soil/land use mapping: GIS Munyao (2010)

volume of ava. water for agriculture (m3) Aquacrop model Raes et al. (2011)

volume of ava. water for domestic use (m3) supply/demand for water -

water quality status

Water Framework Directives,

WHO standards EU (2000); WHO (1992)

water productivity (m3/kg) or WUE water use/ crop yield Oweis & Hachum (2006)

biodiversity (plant/animal species diversity)

Remote sensing/GIS-based

mapping

Vohaland and Barry

(2009)

volume of siltation in reservoirs/dams (m3) field measurements

HR Wallingford (2004);

FAO (2010)

farm income ($/capita) interviews, cross-checking -

Indicators and methods to assess WH systems performance

Constraints Floodwater

WH

Macro-

catchment

Micro-

catchment

Rooftop WH

Climate change (e.g. lack of rainfall)

Insecure land tenure policy -

Conflicts of interest and/or disputes on

water rights -

High cost technology (labor, knowledge)

Off-site adverse effects (e.g. ecological,

socio-economic) -

Little attention/lack of awareness

Prioritizing multidimensional constraints of WH systems

Key: : severe : moderate : small - : very small

Benefits Floodwater

WH

Macro-

catchment

Micro-

catchment

Roof top

Increases water availability for irrigation

Increases water availability for drinking -

Reduces soil loss and erosion - -

Enhances biodiversity (plant, animal species)

Build on local knowledge and practices -

Increases agricultural production and income

Contributes to improvement of livelihoods

Increases adaptation/resilience to CC impacts

Contributes to restoration of drylands -

Analyzing multidimensional benefits provided by WH systems

Key: : High, : medium, : little, - : very little

►Remote sensing/GIS-based modelling to identify suitable WH sites;

►Assessing the trade-offs of upstream-downstream WH practices;

►Engaging downstream and upstream communities in planning,

catchment treatments, M and E of WH projects;

►Providing incentives and enabling policies for long-term

investment on WH harvesting structures;

►Incorporating design of rooftop RWH structures when constructing

residential houses;

►Implementing suitable climate-smart WH practices to restore

degraded arable lands, range lands and/or forests.

some Remarks

Thank

You!