Presentation on theme: "Sustainability of Groundwater Use for Irrigation in Northwest Bangladesh Research Team Nepal C. Dey Md. Abdur Rashid Ratnajit Saha Research Advisor Mahabub."— Presentation transcript:
Sustainability of Groundwater Use for Irrigation in Northwest Bangladesh Research Team Nepal C. Dey Md. Abdur Rashid Ratnajit Saha Research Advisor Mahabub Hossain Sujit K. Bala AKM Saiful Islam Ahsan A. Shopan
Sustainability ? Sustainability R-Resource use GW use indicates depth of GWT in negative value t R
Social Economic Environmental Sustain -ability Environmental Indicators Groundwater table River water contri. to GW Precipitation Groundwater withdrawals Well intensity Evapo-transpiration (ET) Major crops and areas Wetland area Change in crop type Conservation Social indicators No. of people practicing groundwater recharge methods No. of people using alternative sources of water for irrigation or other purposes Peoples’ perception in management Economic indicators Financial Profitability Economic profitability Sustainability Indicators
Challenges Sustainability of GW use for irrigation is becoming a vital concern in many countries of the world, Bangladesh in particular, mainly NW of Bangladesh- where GW declines 5-10m in the dry period (Extracting GW > Recharge capacity) Contribution of GW for irrigation has increased by 2.5 times after 20 years Recurrent below-average rainfall, higher temp causing drought, increased ET, delayed monsoon, dry-up of surface water bodies including ponds, rivers and thus lowering of GWT in the aquifer leading water crisis are some important. Withdrawal of GW
Challenges (contd.) Defects in present IWM practices has been identified. If water is managed properly, BGD can save addl. amount ≈ 1/6 of the total BGD Budget for FY 2003-4 (USD 8,962 million) (Dey et al., 2006), and also similar to the ADP budget of Bangladesh for FY 2009-10 (USD 4072 million). www.iwaponline.com/wp/00806 Irrigation cost increased many folds causing threatens the economic viability of future crop production. Irrigation cost in Bangladesh = > 4times higher than India, 6 times than Thailand and Vietnam. This is mainly because of dependence on GW irrigation
Objectives of the study quantitatively assess the trends in water table depths and crop areas in the designated study area for the past 30 years. financial and economic profitability of different crops along with likely changes over time due to declining water tables. recommend policies for sustainable use of irrigation water in northwestern Bangladesh. In addition, we worked on the following objective- estimate cost of excess water lifted for irrigation.
Methodology Study Area Rajshahi, Pabna, Bogra, Rangpur, Dinajpur District of Northwest Bangladesh Geographically, the study area extends 23 0 48’ 14.3’’ to 26 0 03’ 16.8’’ latitudes and 88 0 18’ 44.99’’ to 89 0 43’ 50.71’’ longitudes. Data Collection Primary Data and Information Sample survey through structured questionnaire (Total number of farm household were 450 where 150 marginal, 150 small and 150 medium/large household) Focus Group Discussion (Five sub-district from five districts of NW Bangladesh) Consultation Meeting Workshop
Data for ET estimation Location: Five Upazilas from five districts in NW region. RS Data: MODIS satellite images & Landsat 7 ETM+ were used in this study. Field coordinates of 131 Boro rice fields located in the selected 5-upazilas were collected using hand held GPS. Secondary Data Data TypeDurationSource Groundwater table depth1981- 2011BWDB, BMDA and BADC Surface water level (25 stations data)1981- 2010BWDB Surface water discharge198 1-2011BWDB Major crops and area1981- 2011BBS Meteorological data (Rainfall, Tmax, Tmin, Humidity, etc.) 1981- 2011 BMD
Data analysis Software SPSS 16.0 and MS Excel ILWIS 3.4 and Arc GIS 9.2 software for image processing and analysis Arc GIS 10 - used for mapping. Financial profitability analysis of major crops : Formula used ∏ = P 1 Q 1 + P 2 Q 2 - ∑P i X i – TFC Economic profitability/comparative advantage of major crops: Border price measured at Farm gate (Import Parity) : P j = P j b + C jm – C jd Border price measured at Farm gate (Export Parity): P i = P i b E 0 -C i Nominal protection (NPC) expressed as: NPC i = P i d /P i b Effective protection
Comparative advantage of crop production Domestic resource cost (DRC) Forecasting of irrigation cost Autoregressive Integrated Moving Average or ARIMA (p,d,q) models used. An AR(p) model has the form: Y t = a 1 Y t-1 + … + a p Y t-p + e t Estimation of ET SEBAL and FAO Penman-Moneith : Where, Go – Soil heat flux, W.m -2 H – Sensible heat flux, W.m -2 λE – Latent heat flux, W.m -2 associated with ET FAO Penman-Monteith method Figure : Components of the Energy Balance
Normalized Differentiate Vegetation Index (NDVI) Map Vegetation indices over NW region GoB-BRAC weather station for climatic data ET + Excess Water Precipitation Estimation of Excess Water
Result and Discussion Groundwater table depths Declining trend of GWT overtime Fig. Changes in depth of GWT depth (Jan-May) over time. Fig. Map of depleted upazilas in five districts Name of depleted upazilas:
River water level Fig. Northwest region river water level fluctuation (yearly avg.) Fig. Changes in river water level (a- maximum, and b-minimum) River water discharge RWL (Yearly avr.) 20.1m 18.3 m RWD (Yearly avr.) 90.8 56.9m 3 /sec Fig. Relationship between RWL & GWT
Figure (a-e). Change in crop area over time at (a) Rangpur; (b) Dinajpur; (c) Rajshahi; (d) Pabna and (e) Bogra district Changes in crop areas 10 major crops’ area has increased 31915 (hectare) where boro alone increased more than 9 times during 1980/81 to 2009/10. Area (Hectare) Δ (09/10- 00/01 ) Δ (09/10- 80/81) Bogra 706127753 Dinajpur 703533142 Pabna 335521158 Rajshahi 1019344076 Rangpur 220031915
Financial profitability of Five major rabi season crops Figure: Cost and return of different crops cultivation Figure: Farm Category wise Benefit Cost Ratio of Boro Rice Figure: Region wise Benefit Cost Ratio of Boro Rice DistrictCosts of boro (Tk/ha) Yield (T/ha) Rajshahi96,8395.819 Pabna96,0806.483 Bogra90,3786.395 Rangpur87,8836.125 Dinajpur86,5836.192
DistrictsMajor Cropping Patterns Suggested Crops according to cropping pattern and BCR Dinajpur 1.Boro-Fallow-T. Amon 2.Wheat-Jute/Maize/Mugbean-T.Amon Wheat production should be emphasized Rangpur 1.Potato-Boro-T. Amon 2.Potato-Maize-T. Amon Potato/ Maize production should be emphasized Bogra 1.Potato-Boro-T. Amon 2.Mustard-Boro-T. Amon Potato/Mustard production should be emphasized Rajshahi 1.Wheat-Fallow-T. Amon 2.Mustard-Boro-T. Amon 3.Chickpea-Fallow-T. Amon Wheat/ Chickpea production should be emphasized Pabna 1.Wheat-Jute-T. Amon 2.Boro-Fallow-Lentil Wheat/ Lentil production should be emphasized Major Cropping Patterns and suggested crops in the study area CropsBCR RajshahiPabnaBograRangpurDinajpur Boro22.214.171.124.221.18 Wheat1.341.36-1.311.37 Potato--1.351.311.24 Mustard1.301.281.351.281.36 Lentil-1.49---
Actual and projected irrigation cost (Tk/ha) Simulation of time path of boro rice production cost and GWT depth 1
Using forecasted irrigation cost (other things reaming same) the financial and economic analysis of boro rice Year Forecasted irrigation cost (Tk/ha) Total cost (Tk/ha) Gross return (Tk/ha) Net return (Tk/ha) BCRDRC 2012 11136.7491928107234153061.170.714 2015 12085.3592876107234143581.150.720 2020 13562.4594353107234128811.140.730 2025 15041.4895832107234114021.120.739 2030 16520.509731210723499231.100.748 2031 16816.319760710723496271.100.750
Changes of NDVI and ET in 2010 21 January 11 April NDVI ET 21 January 11 April ET estimated by SEBAL and Penman-Monteith methods.
Intensity of TW TW intensity: 6.9 to 36 nos/ km 2 DTW became almost double STW reached more than five time higher TW increased 8.5 times where irrigated land increased 1.6 times. Fig.(a) Intensity of TW Fig. b) Increase of TW over time Fig.(c) Increase of irrigated area over time
Excess water extracted Fig. Water requirement & Excess water lifted Fig. NW region Irrigation water requirement and extraction Amount extracted was highest in Badarganj of Rangpur district followed by Godagari of Rajshahi, Birampur of Dinajpur, Chatmohor of Pabna district, and least in Dhupchancia of Bogra district
Environmental Impact 12464.8 T (2010) Pesticides use 3895 T (‘73-90) Polluted water percolation Saline water intrusion OCN S P KZn Nutrient mining
Socio-economic impact Jobless Time and Energy loss for collecting water Health problems Economic loss from pisciculture - drought Nutrition deficiency
Conclusion Sustainability of groundwater use for irrigation in northwest Bangladesh has been identified as a matter of concern. The key impediments of sustainability of groundwater use for irrigation are identified as over exploitation of GW with declining trend, increase of TW nos. and pumping of excess water, increase of boro area, decline of river water flow, decrease of wetland area, less rainfall in the dry period, increase of irrigation cost, poor water management and so on.
Policy recommendations 1. To harmonize boro rice cultivation with other high valued winter crops. 2. Managed Aquifer Recharge (MAR) should be undertaken as a national programme and strategy considering different regional contexts by adopting a series of activities like harvesting of surface and rain water and their storage and conservation through excavation of existing canals, ponds, khals, and water bodies in massive scale. 3. To establish independent Water Regulatory Authority (WRA)/Groundwater Directorate (DR) or any other existing bodies like BADC, DAE might be used for establishing governance and management of groundwater resource to fix and regulate the water tariff system and charges as per Policy Framework. 4. Water User Association (WUA) rooted strong small holder irrigation community should given statutory powers to fix rate determined by WRAs/badc/dae. 5. Optimization of command area of each DTW and STW though consultation with Water User Association where electric connection to pumps is the key component for regulation on GW use and to be realized phase wise i.e., with short term, medium term and long term planning. 6. Irrigation water price should be determined as a rule on volumetric basis in order to meet equity, efficiency and economic principles.
Policy recommendations (contd.) 7. Modern water Management technology liker alternate wetting and drying (AWD), water saving technology like hose pipe irrigation, drip irrigation, drought tolerant crop variety, etc. would bear no value without carrying out irrigation volumetrically. 8. Plan of Action (PoA) in line with basic policies like NAP, PRSP, CIP, NAPA, etc might be formulated under proposed GD or WRA or exsisting BADC or DAE on short term (ST), medium term (MT) and long term (LT) basis. 9. National Sustainable Development Strategies by the government is a good effort to achieve sustainability in all developmental activities specially GW resources of the country under one umbrella. 10. Global Best Management Practices on GW might work as guidelines for going into action for the GW management of the country.
If water is not managed properly, Days are coming when - possibilities of