GBDC increasing the resilience of agricultural & aquaculture systems in the coastal zone of the ganges delta,12 november 2013
1. The Ganges Basin Development
Challenge (GBDC)
Increasing the resilience of agricultural &
aquaculture systems in the coastal zone
of the Ganges Delta
2. The coastal for extrapolation domains
Target areazone of Bangladesh & West Bengal
Outputs
India
4. Why the coastal zone of the Ganges Delta?
• Among world’s poorest, most food insecure, vulnerable rural families
• Dense population >36 million people; >760/km2 (>7.6 per 100 m x 100 m) (2001)
• Low land productivity – 1 low yielding traditional aman crop, much of the land is
fallow during much of the dry season - missed out on the Green Revolution
• Opportunity to build on the achievements & networks of 2 CPWF Phase 1
projects (PN10 Tuong et al.; PN7 Abdel Ismail et al.)
• Good potential to greatly increase land & water productivity (rice, upland crops,
aquaculture, homestead production systems), improve rural livelihoods in the
coastal zone
• The coastal zone offers the potential for Bgd to make a quantum leap in meeting
future food security requirements
4
5. The Ganges Basin Development Challenge – 5 Projects
River
G4. Understanding of water resources – data & models
(current & future scenarios)
Inlet to sluice gate
G2. More productive, resilient & diversified cropping
systems (rice, upland, aquaculture)
Polder 31
G3. Understanding polder water governance –
recommendationson river side
Sluice gate for improvement
G1. Cropping system suitability maps from
Sluice gate inside the
comprehensive GIS data base polder
G5. Co-ordination, liaison with CPWF, policy dialogues,
Polder 30
communication with stakeholders for up & outscaling
6. CPWF Ganges Partner Organisations
BANGLADESH
BFRI Bangladesh Fish Research Institute
IWM
Bangladesh Institute of Water Modelling
BRRI Bangladesh Rice Research Institute
BWDB Bangladesh Water Development Board
LGED Local Government Engineering Board
SRDI Soil Resource Development Institute
CGIAR
World Fish
IWMI
IRRI
BRAC
SocioConsult
Shushilan
PSTU Patuakhali Science and Technology University
BUET Bangladesh University of Engineering & Technology
INDIA
CIBA Central Institute of Brackish Water Aquaculture - Kakdwip
CSSRI Central Soil Salinity Research Institute – Canning Town
6
7. 1,2,3,4,5 =
Intermediate outputs
5. Extrapolation
domains
Water & environmental
criteria
4. GIS data base
2. Improved cropping
systems
Socio-economic
data
-Biophysical
-Census data
3. Water governance
recommendations
G1
IRRI-IWM-BWDBSRDI-LGED
G3 IWMIIRRI-BRRI-BRACWFish-BFRIG2
SocioConsultPSTU
1. Water levels, salinity &
drainage conditions
- Current
- Future
Sushilan-BWDBLGED-BAU
G5
WFish-IRRI-BRAC
G4 IWM-BWDB-BUETIWMI
8. Biophysical constraints to increasing productivity
• Too much water in rainy season (tidal surges in non-protected lands;
excessive rainfall)
• Lack of fresh water in dry season (or lack of access…)
• Salinity, more so in dry season
• Cyclonic events (severe flooding, storm surges sea water intrusion;
death & destruction)
These will worsen due to:
• climate change (sea level rise, more extreme events)
• reduced river flows from India in the dry season
• sinking of the lands protected by polders (consolidation & lack of siltation)
8
9. Annual rainfall ~2,000 mm (range 1,100-2,900 mm)
Mean monthly rainfall - Khulna
mm
400
Aus
Aman
Boro
Boro
300
Rabi
Rabi
Shrimp
Shrimp
200
100
0
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
9
10. Rivers are tidal (to ~150 km inland)
River
River
High tide
River
Draining water
out of polder at
low (still
Low tide tide going down)
Tidal fluctuations up to 2-3 m during the rainy season,
depending on location
10
11. River levels relative to land level
Elevation (above
mean sea level, m)
<0. 0
<0.60
<1.00
<1.20
<1.60
<1.80
%
0
15
61
80
95
98
High tide water level 2.9 m
High tide water level 2.7 m
Average water level 1.3 m
Average water level 1.0 m
Average water level 1.0 m
Low tide water level 0.0 m
Low tide water level -0.50 m
Lower-Shalta river
Kazibacha river
12. Salinity creeps up the rivers during the dry season
– more so in the south west (1 ppt = ~1.5 dS/m)
0-2 ppt
2-4 ppt
8-10 ppt
22-27 ppt
Wet season Sept 2001
Dry season March 2002
12
13. Soil salinity is increasing over time in the coastal zone (dry season)
2009
2000
1973
Salinity boundary
Salinity
None-very slight
Very slight-slight
Slight-moderate
Moderate-high
High-very high
13
SRDI
14. River salinity dynamics in a moderately saline region
24
River water Salinity (ds/m)
High tide
Low tide
21
Batiaghata, Khulna
Polder 30
18
15
1990-2007
12
(Sharifullah 2008)
9
6
3
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
This is not the situation everywhere, e.g.
– fresh water year round in significant parts of the S Central
- river salinity increases earlier & to higher values in the SW
14
15. River
Inlet to sluice gate
Polder 31
Sluice gate on river side
Sluice gate inside the
1960-70s 139 polders constructed to protect the lands from:
polder
• tidal flooding in the rainy season
• salinity intrusion in the dry season
And to enable production of a rainy season (aman) rice crop Polder 30
Polders of SW & SC Bangladesh
~1 Mha
~8 million people
16. Focal study areas in Bangladesh for cropping systems & HH survey
Polder-3
Satkhira
HIGHLY SALINE
Polder-30
Khulna
MODERATELY
SALINE
Polder-43/2F
Patuakhali
VERY SLIGHTLY
SALINE
16
17. Rural households in the polders have very little land
800
CPWF G2 World Fish survey, February 2012 (1,259 HH)
700
# of households
600
500
Functionally landless < 0.2 ha
Marginal 0.6 - 1.0 ha
Large >3 ha
Small 0.2-0.6 ha
Medium 1.0-3.0 ha
400
300
200
100
0
Polder 30
Polder 3-H
Polder 3 L
Polder 43
More than 50% households are functionally landless
ALL Polder
(<0.2 ha)
50 m x 40 m !
* Categories based on Bangladesh Household Income and Expenditure Survey (2010)
17
21. Polder 30
Dense natural drainage
network (former river/creek
canals – “khals”)
Most fields within ~1 km of
a khal in polder 30
11 sluice gates connecting
larger khals to the rivers
21
22. Khals within polders vary greatly in size, can store fresh water during the dry
season, but often heavily silted up (some no longer exist)
22
23. Predominant agricultural cropping systems in the
low & moderately saline regions of the coastal zone
……........Fallow…………………...
Traditional Rice
(2-3.5 t/ha)
Sesame,
Keshari
0.5-1.0 t/ha)
....Fallow……
Traditional Rice
(2-3.5 t/ha)
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
23
24. • Traditional variety
• Tall, photoperiod sensitive (late maturing – harvested Dec/Jan)
• 35-70 day old seedlings
24
26. AFTER RICE HARVEST – some areas
Low input legume crops – late sown (Feb/Mar) because of late rice harvest
Mungbean
Sesame
Often damaged by early monsoon rains – destroyed in May 2013
26
27. High salinity areas
Brackish water
shrimp production
in “ghers”
-extensive to semiintensive
-- high risk
Aquaculture
Aman rice in some
ghers in some
locations in some
years
27
28. Poverty of rural households is extreme in the polders
100
90
% people living below National Poverty Line
(income <$1.25/person/day)
80
% of people
70
60
50
40
30
20
10
0
CPWF G2 survey
by
WorldFish, Februar
Mean
National (2005)
Surveyed Households arginal
m
<0.2 ha
small Functionally landless
28
The CPWF is currently in its 2nd and final phase as it has been subsumed into CRP5 – WLE (Water Land and Ecosystems).In phase 2 it is working on a specific problem, or “Basin Development Challenge” in 6 River Basins around the world, including the Ganges.Here, our challenge is to increase the resilience of cropping systems in the coastal zone of the Ganges. When we talk about cropping systems, these include rice and upland crops, and aquaculture in fresh or brackish water
CPWF works in the coastal zone of Bangladesh and West Bengal in India
Tremendous diversity in space and in time, so much activity, so much indigenous expertise, never a dull moment
Why did CPWF pick the coastal zone of the Ganges?It’s an area in desperate need:Many millions of really poor, vulnerable people dependent on agriculture & aquacultureLow productivity – it missed out on the Green RevolutionBuild on 2 of the best projects in CPWF phase 1 – both were IRRI-ledThese projects showed that there is ….I believe that there is potential for Bdg to
The CPWF Ganges program comprises 5 projects, 4 led by CG centres and 1 by the Bangladesh Institute of Water Modelling (IWM), who do really excellent work. Their task is to provide data, models & model simulations on the water resources in the coastal zoneG2 development & evaluation of improved cropping systemsG3 IWMI leads IRRI leads G1 brings together the findings of all the other projects & other information into a comprehensive GIS database used to identify which improved cropping systems are best suited to which regionsG5, lead by WF, is responsible for overall co-ordination, liaison with CPWF, development of policy dialogues, communication….The scope of each project was designed by a small committee to create a co-ordinated approach to the problem.The projects are inter-dependent, some more than others, and some of them share common members.All the project teams meet together twice a year to share progress, plans and ideasWe also go on field trips togetherRight from the start, we were able to develop some very nice collaboration, synergies and complementarities across the projects, and tremendous sharing and good willMany of us think that this has been the best R4D program that we have ever been involved in, and a model for others to emulate
Partners include 6 Bangladeshi government organisations, 3 NGOs and 2 Bangladeshi universities
But the land productivity of the coastal zone is very low, way behind the rest of BangladeshThe main reasons for this are that …….
3 potential rice cropping seasonsAus – need access to irrigation to establish it after which it is rainfed – grown in limited areasAman – main season – the priority – rice everywhereBoro – grown in the “dry” season - highly dependent on irrigation, very limited areaShrimp – grown in the dry season in more saline areas – sometimes in rotation with aman rice
The rivers are tidal – the coastal zone is defined as the area where the rivers are tidal.The tidal effect extends up to more than 150 km from the coast.These photos taken at same location on polder 30 at high and low tidePeople standing in the figure fishing gives an idea of size of the tidal fluctuation
Example of river tidal levels versus land level – in this case polder 30At high tide the water level in the rivers is way above the level of all the land in the polderAt low tide, the river level is lower than the level of almost all the land in this polder.
Salinity in the rivers increases towards the south west, and towards the coastSalinity fluctuates with the seasons. During the rainy season salinity is lower due to all the fresh water coming down the rivers from India & rainfall runoffDuring the dry season, river flows are much lower, and sea water moves further up the rivers
Salinity is also increasing over the years in the dry season – largely due to reduced flows from India down the riversBut you can see that there are substantial areas of the coastal zone where salinity is low – especially in the SC coastal zone where there are huge fresh water flows down the rivers even in the dry season
This is an example of the river water salinity in a moderately saline region. Here, the river water becomes too saline for use for irrigation in mid-Feb, and remains too saline until end of June
Much CPWF Ganges work is focussed in the polders of the coastal zone of south west and south central Bangladesh.
We have surveyed over 1,200 households and are developing and evaluating cropping systems in 3 polders representing low, medium and high salinity regionsThere is also detailed water level and salinity monitoring in and around these poldersWater governance is also being studied in these polders, and several others.
Our rural household survey of these 3 polders showed that farm size is extremely small.More than 50% of rural HH have less than 0.2 ha of land – less than 50 m x 40 m!The situation is pretty much the same right across the coastal zone
Here we are zooming in on our study polder 30, a smallish polder of ~4,000 ha surrounded by large rivers on all but the SW perimeter.In the next slides I will be showing you some photos from the location of the red spot
The top photo shows the large river on the east side of polder 30. The bottom shows the river at high tide on the left. The land inside the polder is flooded with about 20 cm of water. Clearly the land surface inside the polder is at a much lower level than the water in the river at high tide. Imagine the flooding if the dyke was not present – the land would be totally submerged to a depth of 1-2 m twice daily during the rainy season
These photos were taken at a sluice gate in the polder embankment at the same location – at high tide. The sluice gate was open to let more water into the polder so that the higher lands could be irrigated for puddling for riceThe photos on the right were taken at low tide – this time the sluice gate is open to drain water out of the polder
In addition to being surrounded by rivers, polders have a dense natural drainage network inside – all the blue squiggly lines. In this polder, most lands are within about 1 km of a khal
As a result, poverty of rural HH in the polders is extreme
But there is high potential for greatly increasing the productivity of the coastal zone and improving livelihoods, and that is what the CPWF Ganges projects are working towards.