Climate Change and Sustainable Irrigation Management for High Value Crops in Bangladesh. by Md. Shirazul Islam and Md.

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2 Climate Change and Sustainable Irrigation Management for High Value Crops in Bangladesh by Md. Shirazul Islam and Md. Harun-ur-Rashid

3 Predictions World Watch Institute (2007) Bangladesh is under serious risk from sea level rise due to climate change Ahmed and Roy (2007) Climate change will disrupt significantly the agro-environmental practices and socioeconomic activities of the country

4 Predictions (continued) Koudstaal and others (1999) Salinization in the dry season and prolonged inundation in the wet season Hassan and Hoque (2008) Flood area will increase by about 6% resulting in crop production loss of about 11% in the Ganges basin, 7% in Meghna basin and 2% in Brahmaputra basin

5 Selvaraju (2006) Increase winter temperature affecting wheat and pulse cultivation, increase spikelet sterility and reduce crop yield

6 Irrigation & Water Management Scenario in Bangladesh

7 Summary of irrigation equipment and area coverage Equipment Number in operation Area coverage (ha) % of total irrigated area DTW 27,117 6, STW 11,28,991 31,59, LLP 99,255 8,38, Gravity flow - 1,09, method Traditional method - 25, Source: Minor irrigation survey report , MoA, Bangladesh

8 Groundwater irrigation About 75% groundwater irrigation About Mm 3 of groundwater is needed annually for irrigation

9 Groundwater irrigation (continued) Water table declination is observed in many irrigated areas of the country This has restricted the use of suction mode pumps in the areas

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11 Water distribution systems Mostly unlined channels A few buried pipe water distribution systems Some lined channels High water loss in distribution systems Low system efficiency (Rice: average 30-35%; Other crops: 40-60%)

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14 Losses in distribution systems Distribution system Water loss (l/s/100 m) Buried pipe (BP) Lined channel system Unlined channel system Flexible (hose) pipe

15 Tubewell utilization No regulation on irrigation appliances since 1992 Density of installation of shallow tubewells increased Irrigated area of <0.5 ha under a 14 l/s capacity STW

16 Tubewell utilization (continued) Tube wells installed in light textured soils, irrigate almost every day causing huge seepage and percolation losses

17 Effect of Climate Change on Soil, Water and Crop Production

18 Effect on Soil Characteristics Potential changes in soil organic matter supply from biomass, soil temp. and soil hydrology Other changes due to change in temperature and precipitation are expected to be relatively well buffered by the mineral composition, the organic matter content or the structural stability of many soils

19 Effect on water productivity Water productivity will be limited by the amount of water available Due to erratic climatic conditions, more area are expected to come under water restrictions giving rise to low water productivity

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21 Water productivity of some crops Crop Water productivity (Kg/ha-mm) Rice 5-6 Wheat Maize Potato Tomato Brinjal Onion 25-30

22 Effect on Crop Production Shallow rooted plants will suffer most With the rise of temperature, plants will require more water for evapotranspiration Unless the cropwater demand is met, yield will decrease

23 Effect on Crop Production (continued) Some crops will be eliminated or produce less yields Increased insect infestation and pest and disease infections to crops will appear as a great problem

24 Effect on Soil Salinity Bangladesh has, at present, about 1.0 mha of lands under various levels of salinities which is expected to increase further and extend towards inland

25 Category of soil salinity and saline areas Category of salinity (ds/m) Mapping S Unit 1 S 2 S 3 S 4 S > Total Source: SRDI (2000)

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28 Effect on Drought Every year, 3-4 million hectares of land are affected by droughts of different magnitudes Stress resulting from higher crop ET and reduced rainfall may override any growth benefits from the higher CO 2 levels, unless irrigation can be stepped up to compensate the deficit soil moisture

29 Effect on Drought (continued) Aman rice is grown rain fed in about 60% of cultivable land (8.3 Mha) The crop suffers from drought of different intensities A heavy loss to Aman production affects the economy of the farmers

30 Drought Intensity and yield loss of T. Aman Intensity of drought Land area, hectare Yield loss due to drought,% Very severe Severe Moderate Slight

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32 Effect on Floods Climate change will cause greater intensity floods damaging more crops, lives and other properties Flash floods will also be frequent and dangerous for some areas of the country

33 Effect on Floods (continued) In 2002, flash floods damaged shelters and crops of about 31,500 hectares in 12 upazillas of Chittagong and Cox s Bazar districts In 2007, flood hit twice a year damaging the crops, human and cattle lives and shelters, and other properties

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35 Effect on Cyclones and Tornadoes Climate change will enhance frequent cyclones and tornadoes of high intensities This will threaten Bangladesh agriculture most

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37 Possible Measures for Sustainable Water Use in Crop Fields

38 Optimization of Water Use Already the drying and wetting method of water application has been proved to be very useful to save 50% water without any or a little sacrifice of rice yield

39 Use of drip irrigation method High value crops like tomato, egg-plant, potato, papaya, watermelon etc. can be irrigated For saline soils, this method can be a good choice for the coastal farmers

40 Controlled Application of water Fertigation

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42 Crop production in saline soils Methods used Drip, raised bed and mulch Traditiona l method Location: Noakhali Crop Yield, Salinity, t/ha t/ha Tomato ( ) Watermelon Tomato Watermelon ( ) Location: Satkhira Crop Yield, Salinity, t/ha ds/m Tomato ( ) Okra Tomato Okra N.B. Figures in parenthesis indicate reduced soil salinity due to improved management practices 9-10 ( )

43 Improved distribution system Channel compaction has been found to increase command area by about 10-30% Proper use of a good quality hose pipe can save 95% water loss

44 Improved distribution system (continued) Buried pipe water distribution system (BPS) It can take care of land undulation, land loss (1.8-2%), irrigation cost and water distribution uniformity

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46 Change in cropping pattern 1. A change in cropping pattern in these areas with non-rice crops can make irrigation much more profitable 2. Low water requiring crops like wheat, maize, potato and horticultural crops can be grown for more benefits

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48 Annual water requirements of different crops Name of crop Area cultivated, 000 ha Seasonal crop water requirement, mm Approx. Irrig. water requirement, Mm 3 Rabi season (October-February) Boro rice Wheat Potato Maize (w) * Mustard Groundnut Vegetables(w) * Onion Garlic Sub-total N.B: (w) * = winter; ** = Supplemental irrigation

49 Annual water requirements of different crops (continued) Name of crop Area cultivated, 000 ha Seasonal crop water requirement, mm Approx. Irrig. water requirement, Mm 3 Kharif-I season (March-May) T.Aus** Vegetables** Maize** Sub-total 7483 Kharif-II season (June-September) Aman rice** Sub-total 3461 Grand Total: Mm 3 N.B: (w) * = winter; ** = Supplemental irrigation

50 Construction of water management infrastructures The constructed structures provide flood protection to about 3.5 million ha of land In the coastal areas over 12 million people are receiving the benefits of around 3,600 km embankment

51 Maintaining well spacing regulation

52 Conjunctive use of water Conjunctive use of surface and ground water for sustainable irrigation management Government has also emphasized on surface water utilization to reduce pressure on groundwater

53 Upgrading Farmers Knowledge Most of the farmers of the country are illiterate and do not have much idea about consequence of the misuse of irrigation water They should be made aware of the water managements in irrigated agriculture through trainings, demonstrations and group discussions

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55 Conclusions Water conveyance systems should be improved Irrigation of diversified crops, especially the high value crops, should be encouraged Farmers should be made aware of water losses and the ultimate effects Conjunctive use of water for irrigation should be encouraged

56 conclusions (continued) Government should take necessary measures to install Buried Pipe Water Distribution Systems by phases all over the country Existing rules of tubewell installations should be revived Mass media should be used to propagate the water management messages to general people

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