Urs Schulthess ⏐Timothy J. Krupnik ⏐Zia Uddin Ahmed ⏐Andy J. McDonald

Decentralized Surface Water Irrigation as a pathway for sustainable intensification in Southern Bangladesh:

On how much land can the drop be brought to the crop?

A three part presentation:

1.  Surface water irrigation as a pathway to sustainable intensification (SI) in Southern Bangladesh

2.  Targeting decentralized surface water irrigation to boost double cropping

3.  Future research and conclusions

Part 1: Surface water irrigation as a pathway to sustainable intensification (SI) in Southern Bangladesh

Mean dry season groundw

ater table depth (m)  

The emerging irrigation bottleneck in intensive boro production zones

Source: Qureshi, Ahmed, and Krupnik (2014)

The Master Plan For Agricultural Development In The South

The Southern Delta of Bangladesh •  Low crop intensification and fallows •  3.44 million farm households, majority poor

(MoA and FAO, 2012)

•  Rice-based farming system •  Target for most international aid

The Southern Delta Master Plan: A $7.2 billion donor investment request •  The south: Dense network of rivers and

canals, poorly used for irrigation •  Emphasis on expanding surface water

irrigation to alleviate irrigation bottlenecks in the North

•  Key aim: sustainable intensification to boost productivity and alleviate poverty

Sustainable intensification (SI) in Southern Bangladesh

In practice, SI has two major approaches: •  ‘Crop’ intensification:

Boosting yield, while sparing resources and harnessing ecological services (e.g., yield focused)

•  ‘Systems’ intensification: Moving from one to two crops, while sparing resources and harnessing ecological services (e.g., double cropping focused)

•  Bangladesh: loosing agricultural land (-10% in the last decade) (Hassan et al. 2013)

•  SI: ‘. . . producing more output from the same area of land while reducing the negative environmental impacts and … increasing contributions to natural capital and the flow of environmental services’ (Pretty et al. 2011)

Irrigation a must to scale up double cropping in Southern Bangladesh

How can dry season irrigation be encouraged? •  Large-scale, centralized irrigation schemes?

Extremely costly and challenging to maintain:

•  Ganges-Kabadak (1955) – most land in 72,000 ha already double cropped. Siltation, bank instability, etc. (Brammer, 2002)

•  Barisal Irrigation Project (1980). Slated for 42,000 ha achieved < 20% (cf. Gumma et al., 2014).

•  Unfavorable conditions for farmers to access and use state provided pumps (Brammer, 2002)

•  Bangladesh’s historical irrigation boom: thousands of decentralized irrigation service providers serving 10–20 ha

Supplies 90% of Bangladesh’s irrigation (Chowdhury, 2010)

Could this work for Southern Bangladesh?

•  Technological options exist to address energy and cost problems (Axial flow pumps, other pumps)

•  Service provider networks and water users groups need to be established

•  Problems remain with appropriate siting of small command schemes to encourage double cropping

Krupnik et al. 2013

Part 2:

Targeting decentralized surface

water irrigation to boost double cropping

Forgoing the fallow and establishing rabi cropping

•  Location and estimates of fallow land vary by year, method, and definition: •  800,000 ha (Rawson et al., 2011)

•  634,000 ha (BADC 2010)

•  136,000 ha (MoA and FAO, 2012)

•  240,000 ha (BBS, 2011)

•  No estimates are related to targeting fallows for surface water irrigation and intensification

•  Analytical challenges: Fallow identification, soil and water salinity, water availability, timely land availability

Targeting ‘best-bet’ areas for intensifying cropping using surface water irrigation in S. Bangladesh

A complex process using GIS and remote sensing (RS) Using publically available data •  Hydrozone à GIS •  Water ways à RS •  Duration of surface water à RS •  Water salinity à monitoring/GIS •  Soil salinity à survey/GIS (SRDI) •  Land type à Elevation •  Crop land à RS •  Land use intensity à RS

Study area: South Central and South West Bangladesh

Area:  3.374    million  ha  

Dynamic river system

feetkm

40001

feetkm

40001

feetkm

40001

Apr  12,  2014  Nov  23,  2009  Feb  17,  2004  

Surface Water

Presence of surface water in January

Feyisa,  G.L.,  Meilby,  H.,  Fensholt,  R.,  Simon,  R.,  Proud,  S.R.,  2014.  Automated  Water  ExtracKon  Index:  A  new    Technique  for  surface  water  mapping  using  Landsat  imagery.  Remote  Sensing  of  Environment  140,  23-­‐35.  

Presence of surface water in February

Presence of surface water in March

Surface water salinity in January

Source  of  surface  water  salinity  data:  BWDB.  Data  from  2002–2012  were  used.  

Surface water salinity in February

Surface water salinity in March

Surface water salinity in April

Soil salinity

Source:  SRDI,  2000.  Soil  Salinity  Bangladesh.  Soil  Resources  Development  InsKtute.,  Dhaka,  Bangladesh.  

Suitability Matrix based on surface water and soil salinity

0"#2 "2"#"4" >"4"0"#2" Highly"suitability Medium"suitability Non"suitable"2"#"4" Medium"suitability Low"suitability Non"suitable>"4 Non"suitable Non"suitable Non"suitable

Water&Salinity&[dS/m]

Soil&Salinity&[dS/m]

Land suitability based on soil and surface water salinity

Landscape elevation (Kharif inundation class)

Above  flood  level  

Up  to  90  cm  

90  –  180  cm  

180  –  300  cm  

>  300  cm  

Normal  flooding  depth  

A\er:  Brammer,  H.  2012.  The  physical  geography  of  Bangladesh.      

Reflectance of light from leaves as function of wavelength

NDVI = NIR - Red

NIR + Red Normalized  difference  vegetaKon  index  

27

Ground Cover (GC) and Leaf Area Index (LAI)

Ground Cover is the percentage of ground covered by green vegetation when seen from above. It is a good indicator of: Productivity Stresses Diseases

GC  =  1  –  exp(-­‐k  *  LAI)  

Prediction of LAI with the Enhanced Vegetation Index (EVI)

Guindin-­‐Garcia,  N.,  Gitelson,  A.A.,  Arkebauer,  T.J.,  Shanahan,  J.,  Weiss,  A.,  2012.  An  evaluaKon  of  MODIS  8-­‐and  16-­‐day  composite  products  for  monitoring  maize  green  leaf  area  index.  Agric.  For.  Meteorol.  161,  15-­‐25.    

Using EVI to assess rabi land use intensity

2013-14

Using EVI to assess rabi land use intensity

2013-14

Using EVI to assess rabi land use intensity

2013-14

Using EVI to assess rabi land use intensity

2013-14

Using EVI to assess rabi land use intensity

Using EVI to assess rabi land use intensity

Using EVI to assess rabi land use intensity

Resulting land use intensity, rabi 2013–14

Resulting land use intensity in Southern Bangladesh (ha)

Cropping intensity 2011–12 2012–13 2013–14 Average Fallow land 271,078 218,806 230,824 240,236 Low-intensity 779,095 915,548 906,382 867,008 High-intensity 876,338 790,732 789,735 818,935

Total 1,926,179

Resulting land use intensity in Southern Bangladesh (ha)

Cropping intensity 2011–12 2012–13 2013–14 Average Fallow land 271,078 218,806 230,824 240,236 Low-intensity 779,095 915,548 906,382 867,008 High-intensity 876,338 790,732 789,735 818,935

Total 1,926,179

Compared to previous estimates for fallow land:

•  800,000 ha (Rawson et al., 2011)

•  634,000 ha (BADC 2010)

•  136,000 ha (MoA and FAO, 2012)

•  240,000 ha (BBS, 2011)

All methods based on survey sampling and up-scaled estimation, with exception of Rawson et al., who included low-intensity crop land.

Targeting surface water irrigation to fallow and low land use intensity land

Detailed view: Land use intensity

Detailed view: Targeting surface water irrigation on fallow and low land use intensity land – 400 m buffer

Addressable land (ha) within a 400 m buffer of detectable surface water bodies (late March)

Land use Highly Medium Low Not Intensity Suitable Suitability Suitability Suitable Fallow 14,524 6,866 2,144 23,631 Low Intensity 86,451 17,262 6,640 22,302 High Intensity 66,639 6,524 999 7,419 Total 167,615 30,652 9,783 53,352

The key output of this work is a detailed spatial database indicating the precise location of high- and medium- suitability fallow and low intensity lands upon which surface water irrigation could provide the key to unlocking the South’s agricultural productivity. This data base will soon be online and made available for development organizations, researchers, and policy makers.

Caveats •  Our estimate is conservative:

FINNMAPS indicate we detected just ~25% of rivers and canals in the irrigable zone

•  Methods are needed to rapidly assess water volume

•  Cooperation is key: Good water governance and canal rehabilitation will be crucial for sustainable intensification.

•  Research is needed to fine-tune irrigation scheduling recommendations to increase WP

Part 3:

Future research: IrMASaT project (Irrigation Management Advisory with Remote Sensing)

Main high potential target zone for surface water irrigation Objectives:

•  Regional and sub-regional watershed and scales: “safe operating space in canal systems”

•  Surface water irrigation scheduling optimized: Maize, wheat, boro, mungbean

Octocopter and satellite images to address the spatial variability

Thank you! Questions?

u.schulthess@cgiar.org

Land suitable for technology targeting