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GBDC increasing the resilience of agricultural & aquaculture systems in the coastal zone of the ganges delta,12 november 2013
 

GBDC increasing the resilience of agricultural & aquaculture systems in the coastal zone of the ganges delta,12 november 2013

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by: Dr.Craig A Meisner

by: Dr.Craig A Meisner
Presented at the GBDC Reflection Workshop,November 2013

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  • 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.

GBDC increasing the resilience of agricultural & aquaculture systems in the coastal zone of the ganges delta,12 november 2013 GBDC increasing the resilience of agricultural & aquaculture systems in the coastal zone of the ganges delta,12 november 2013 Presentation Transcript

  • The Ganges Basin Development Challenge (GBDC) Increasing the resilience of agricultural & aquaculture systems in the coastal zone of the Ganges Delta
  • The coastal for extrapolation domains Target areazone of Bangladesh & West Bengal Outputs India
  • 3
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • Polder 30 (~4,000 ha) 18
  • River on eastern side of polder 30 Polder embankment /dyke protecting land from flooding at high tide River-side Dyke 19
  • River River River Sluice gate letting water into the polder at high tide Sluice gate draining water out of the polder at low tide 20
  • 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
  • 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
  • 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
  • • Traditional variety • Tall, photoperiod sensitive (late maturing – harvested Dec/Jan) • 35-70 day old seedlings 24
  • AFTER RICE HARVEST - much fallow land – for 5-7 months Soil salinity 25
  • 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
  • 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
  • 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
  • High potential of the Ganges coastal zone