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Chowdhury Sarwar Jahan Ph.D. Professor Dept. of Geology and MiningandPro-Vice Chancellor

BARIND AREA,NW BANGLADESH

DROUGHT, GROUNDWATER SCARCITY AND ADAPTATION MEASURESUniversity of Rajshahi

Groundwater based irrigation directed to cultivate high-yielding rice during dry season in South Asia Bangladesh: Worlds 4th largest rice-producing country (Scott and Sharma, 2009 and IRRI, 2010)More than 75% water for irrigation comes from groundwaterDrought common in NW Bangladesh especially when monsoon curtailed

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BANGLADESH AND BARIND Area

IndiaIndiaGanges RiverMeghna RBarind Area

Drought-prone areas in Bangladesh

Agro-based drought prone NW Bangladesh granary, where agricultural practices depend mostly on groundwater irrigation BIADP launched in late 80s of last century to achieve sustainable agricultural growth in Barind area covering 7,500 km2Multi-cropping agricultural practices boosted crop intensity from 117% (pre-BIADP) to 200% (at present) (national avg. 175%)Scope for 8728 DTW of 2-cusec capacity (BMDA), presently running ~15000 DTWsDemand of groundwater irrigation increases day by day Barind Area

PhysiographyPhysiographic MapLandforms: Barind Tract Floodplains

Barind Tract N-S dome shaped area (20- 25 km wide in E-W direction) Edged parallel to river valleys Elevation 47.0 m in central part to 11.0 m in the SE

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CLIMATE ScenarioThree seasons: Winter (Nov-Feb) - Cool & dry with almost no rainfall Pre-monsoon (Mar-May) - Hot & dry Monsoon (Jun-Oct) - Rainy

Rainfall Pattern

Annual Avg. Rainfall (1971-2011): 1326 -1650 mm (avg. 1505 mm)Seasonal Mean Rainfall Winter: 36 mm (2.4%) Summer: 220 mm (12.6%) Rainy: 1248 mm (83%)Distribution of Annual Rainfall

Rainfall Trends Decreasing trend in annual rainfall (MK Z = -0.75) Slope: Q = -2.76 mm/year

Trend in Annual Rainfall

Trends in Season RainfallIn 15 rain gauge stations, negative trends found in Winter: 73% Summer: 53% Rainy: 60% Trend in Winter Season

Trend in Summer Season

Trend in Rainy Season

MK Z StatisticsStationsJanFebMarAprMayJunJulAugSepOctNovDecRajshahi-1.07-1.780.40-0.600.570.28-1.24-0.78-0.35-0.30-1.05-1.36Tanore-1.02-0.550.83-0.310.24-0.36-0.690.390.440.82-0.27-1.15Godagari-0.75-1.350.99-0.560.530.93-0.28-1.19-0.17-0.15-1.32-0.92Bholahat-0.210.491.340.540.810.92-0.740.01-0.340.44-0.21-1.16Nachole0.45-0.751.930.00-0.951.63-0.24-0.64-0.08-1.03-0.31-0.06Nawabganj0.23-1.210.680.580.541.441.67-0.351.120.19-1.01-0.98Rohonpur-0.55-2.130.77-0.030.561.64-2.20-0.94-1.44-0.25-0.52-2.49Shibgonj0.01-1.212.160.00-0.100.24-0.08-1.70-0.25-0.46-0.24-0.62Atrai0.22-1.381.570.19-1.21-0.15-0.86-0.81-0.66-0.06-1.410.52Badalgachi-0.79-1.970.580.49-0.980.69-2.01-0.20-1.070.13-0.42-1.16Manda0.04-0.731.360.661.391.54-0.570.460.480.930.77-0.94Mahadebpur-1.64-2.020.50-0.92-0.550.03-2.59-0.21-0.800.26-1.85-2.09Porsha-1.01-1.890.65-0.69-0.991.77-0.95-0.06-0.900.75-0.19-1.96Naogaon-0.71-1.760.440.420.150.56-1.44-0.45-0.31-0.10-1.16-1.23Sapahar-0.78-1.26-0.410.26-0.782.44-2.551.020.100.850.16-2.13Negative1014167214111171314Positive51147813144821%Negative66.793.36.740.046.713.393.373.373.346.786.793.3%Positive33.36.793.346.753.386.76.726.726.753.313.36.7

Trends in Monthly RainfallAlarming Situation for Mid Monsoon Period

Rainfall VariabilityRainfall Variability Map Annual & seasonal rainfall variability very high Indicate high uncertainty of getting rain water :Annual: 26% Winter: 100% Summer: 54% Rainy: 27% Difficult for Water Management Plan in High Rainfall Variable Area (as rainfall getting uncertainty over 20%) Results frequent droughts

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Seasonality Index (SI) & Changes SI Indices: 0.84-0.89 (Avg. 0.87)Rainfall markedly seasonal with long dry season

93% rainfall occurs: May-Oct with certainty from Jun. - Sep.Area receive 39% less rainfall than national avg. (2456 mm)Monthly Rainfall Pattern

SI IndexTrend in SIRainfall scarce area in Bangladesh

Precipitation Conc. Index (PCI)PCI: 18.26-21.42 (Avg. 19.84) Indicates irregular to strongly irregular distribution of rainfallHigher value reveals huge pressure on water resourcesSI and PCI indicate rainfall occurred in few months with short rainy days making water scarce area

Distribution of PCI

TemperatureAnnual mean temp.: 25.23CIncreases at +0.02C/year

Annual Mean Temp DistributionAnnual Mean Temp. AnomalyHumidity

Annual Mean Humidity Distribution

Trend in Humidity Mean Annual Humidity:76.49%Annual magnitude of change: 0.09%

Drought and ENSO Phases (El Nio and La Nia) SPI-3 (Agricultural Drought): Twelve Moderate - Extreme drought : 1972, 1975, 1979, 1982, 1986, 1989, 1992, 1994, 2003, 2005, 2009 & 2010

SPI-3 Series in Study Area

SPI-6 Series in Study Area SPI-6 (Meteorological Drought): Twelve Moderate - Extreme droughts: 1972, 1975, 1979, 1982, 1986, 1992, 1994, 1995, 1996, 2005, 2009 & 2010

SPI-12 Series in Study Area SPI-12 (Hydrological Drought): Moderate-Extreme droughts: 1972, 1975, 1976, 1979, 1982, 1983, 1986, 1992, 1994, 1995, 2008, 2009 & 2010

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In Bangladesh, seasonal average rainfall shows:Negative general tendency during strong El Nio yearsRelation between rainfall variability and ENS index very high in Ganges basinIn Barind area: 75% Historical drought events related to El Nio variability

Annual Drought OccurrencesWith increasing severity of drought, high drought occurrences shift toward south & central parts of area Southern & central parts of Barind area, mostly affected by hydrological drought puts stress on groundwater resources

Drought during Rainy Season Drought trends increase during rainy season results:Agricultural drought: 61%Meteorological drought: 59% Hydrological drought: 50%Critical reproductive stages of T. Aman rice with reducing yield

Decadal Drought Events Dry episodes: Highest in recent decade Mild & Moderate drought: Increases rapidly in rainy & summer seasons Severe & Extreme drought: Fluctuating Cumulative Decadal Drought Events

Drought Risk

Category Drought Frequency (year)AgriculturalMeteorologicalHydrologicalMild 2.22.32.6Moderate 10.313.76.8Severe5.94.68.2Extreme 8.220.58.2

Class B: Moderate-High risk condition & should be addressed by adaptation

Area belongs to humid zone and semi-aridity creeping towards Northern part Aridity INDEX DistrictUpazillaClassification of Aridity Index(range values in parenthesis for humid zone)Aridity Zone P/PET (>0.5)AL (>40)1980-901991-091980-901991-091980-901991-09Chapai-NawabganjRohonpur42.8138.480.90.8860.1453.37HUMIDShibganj41.3545.410.881.0457.7962.96Nawabganj35.141.870.730.9649.358.07Nachole42.342.720.890.9859.4259.25Bholahat49.542.191.040.9769.5458.51NaogaonPorsha42.749.070.891.1259.9968.06Shapahar43.5542.660.910.9861.1859.16RajshahiGodagari43.137.820.90.8760.5552.46Tanore44.6447.610.931.0962.7166.02

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Chapai-Nawabganj and Rajshahi districtsNaogaon districtMonthsETBoroETWheatETPotatoETBoroETWheatETPotatoJan2.792.7853.02.752.743.13Feb4.170.9453.813.940.893.77Mar5.90****5.53****Apr7.13****6.53****May************Jun************Nov**0.8451.785**0.8151.725Dec**1.742.275**1.652.17

ET values (mm/day) for cropsETcrop values for:Paddy (Boro) as dominant crop > Wheat & Potato

Cultivated areas of rice: Aman (78%), Boro (67%) and Aus (47%)

Groundwater Scenario

GENERAL ANNUAL TREND OF GWT Recent declining rate higher than earlier. After 2002-2004, GWL not return to original level

SapaharNacholeTanoreGodagari

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Annual Max. Depth to GWT

199120101991: GWT was near suction limit except central part (Avg. depth 8.76 m)2010: GWT mostly below suction limit (Avg. depth 12.95 m)People not getting drinking water by HTW and now use submersible pumps for drinking water

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TREND OF GWT (SUMMER Season)Linear Trend shows decreasing trend in GWLMK Test Z = 4.96 (at 99% CL)Slope Q = 0.201 m/year (0.7 ft)Analysis of 73 monitoring wells data shows trend of GWT: Significantly declining (84%) Insignificant declining (11%) Increasing trend (5%)

MAKESENS Model IN Dry Season GWT

GWT SCENARIO (SUMMER Season) by MAKESENS Model

Linear Slope

a

bMAKESENS :SlopeMAKESENS: Intercept Very High Decreasing Rate in Barind Area (0.7-0.8 m/year or 2.30 ft/year)

2020: 4.58-39.9 m (mean: 15.44 m) 2030: 4.58-46.83 m (mean: 17.31 m) 2040: 4.58-53.76 m (mean: 19.17 m)2050: 4.58-55.61 m (mean: 21.04 m)Projected Scenario of gwt (SUMMER season) (depth to water TABLE)

2020203020402050

TREND OF GWT (RAINY Season)Linear Trend shows decreasing trend in GWLMK Test Z = 4.51 (at 99% CL), Slope Q = 0.201 m/year (0.7 ft.)Analysis of 73 monitoring wells data shows trend of GWT: Significant declining (74%) Insignificant declining (21%) Increasing trend (5%)

MAKESENS Model of Wet Season GWT

GWT Scenario (RAINY Season) by MAKESENS ModelHigher decreasing rate of GWL in central part of Barind area (0.6-0.7 m/year or 2.13 ft/year)

MAKESENS: Intercept

MAKESENS: Slope

Linear Slope

2020: 1.36-27.14 m 2030: 1.36-34.58 m 2040: 1.36-42.02 m 2050: 1.36-49.49 m

2020203020402050Projected Scenario of GWT (RAINY season )(depth to water TABLE)

Groundwater Table Depletion (1991-2010)

Dry Season

Rainy Season

AverageDepletion of GWT (1991-2010): Dry season: 12-22 mRainy season: 8.5-14 mCentral Barind area: Avg. 9-14 mFloodplain area: Avg. 4-6 m

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Amount of Groundwater DepletionSo 1-2 % annual rainfall must be harvested to protect GWT depletion (High Barind: 2-3%)

Annual avg. amount of groundwater depletion (1991-2010): 114 Mm3 Average total annual rainfall: 11000 Mm3

Relationship between Rainfall & GWL

Decreasing rate of rainfall: 1991-2011 > 1971-2011

Decreasing trend in rainfall consistent with progressively declining trend of GWT

RELATIONSHIP BETWEEN GWT & SPI In general annual avg. & annual min. depth of GWT influenced by SPI values of rainy season

In Barind Area, changes in SPI values coincided with changes in depth of GWT

IRRIGATED AREASTotal irrigated areas by PPs, STWs and DTWs: 5,29,000 acres (1993-94) 17,78,000 acres (2011-2012)Total 23,565 hectares of land (6.72% of total irrigated area) can be irrigated by surface water resources in Barind area

Condition worsening due to increasing irrigated areas

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Groundwater Recharge vs. NIRComparison between NIR for paddy (Boro), wheat & potato, NGR, PGR & UGR reveals: NIR of paddy (Boro) exceeds PGR Cultivation of Boro rice: 62% of cultivated area

Production of rice over years increase that helps country to ensure food security

Declining trend of GWT (Summer and Rainy Seasons) indicates:Groundwater resource depletion and depth GWT will be almost double by 2050 than present situation So groundwater will be scarce in forth coming days resulting unsustainable resource for development People will have to replace normal pumps by submersible pumps even to get drinking waterUltimately hamper ecological balance of areaStress on groundwater resource will increase day by day & becomes acute with extension of irrigated agriculture along with climate variability

Adaptation Measures

Schematic Diagram of MAR Technique

Features of Recharge StructureInstalled: November, 2013Total catchment (roof of corrugated iron): 200 m2 from where rainwater from roof is used to recharge aquifer through pipes Recharge points in each village: Five and rainwater from roof used to recharge aquifer through pipesRainwater before injecting into recharge structure: Makes free from silt and debris Recharge box: 1.5 m 1.5 m size filled with sand and brick cheeps of 6 mm, 10 mm and 20 mm sizesDepth of recharge box: 3 m in top clay layer (Zone-I)GWT monitoring well diameter: 15.25 cm

Recharge BoxCollection PipeInterior of Recharge BoxRWH: Sharing with PeopleObservation WellRain Gauge Station

ENGINEERING ASPECT OF RWH

GROUNDWATER TABLE FLUCTUATION BEFORE MAR APPLICATIONTill 2004, GWT came back to its original position, but after that fluctuation of GWT remained at minimum level due to inadequate groundwater recharge with prevailing drought condition in Barind Area

MaxMinGWTFAvg.(91-95)14.65.29.4Avg.(96-00)17.24.812.4Avg.(01-05)18.16.711.7Avg.(06-10)18.912.26.5

Average GWT depth (m) in Nachole Area

GROUNDWATER TABLE FLUCTUATION AFTER MAR APPLICATIONAfter MAR Application situation started to reverse, GWT rising in response to artificially augmented rechargeYearMallickpur VillageGanoir VillageMax, mMin, mMax, mMin, m201413.665.8034.1326.002015 09.885.532.6625.7

CHIMISTRY OF GROUNDWATERPhysical ParametersPre-MAR TechniquePost-MAR TechniqueRemarksWHO(2008) / BDWS(2004) / EU (1998) / ECR(1997) StandardpH6.9-7.27.1Neutral TypePermissible qualityEC s/cm519-675500Moderately salineSafe for drinking purpose and irrigation on almost all soilsTemp.0C25.5-26.026.0 Chemical ConstituentsCa2+ mg/l46.4- 72.536.2Within drinking and irrigation quality standardFetotal mg/l0.48-1.291.16SO42- mg/l0.5-0.60.6PO4- mg/l0.40-0.500.30NO3 mg/l05.0-08.00.50As mg/l 0.01 0.01Free from toxicityFree from hazardFecal ColiformNilNilSafe for drinking purpose

Quality of Groundwater before and After MAR is Safe for Drinking & Irrigation

Well Recharge Model FOR RWHSingle Chamber Model for Mondumala Pourashova Building, Tanore

CONSTRUCTION PHASE OF WELL RECHARGE TECHNIQUE FOR RWH IN Mondumala Pourashova BUILDING

Dug Well Recharge FOR RWH Dug well recharge for RWH in Kakon Hat Pouroshova and Auditorium Building

CONSTRUCTED Cross Dam SITE FOR SURFACE WATER CONSERVATION IN GOBRATALA AREA, CHAPAI-NAWABGANJ

THANKSCatch Water Where It Falls

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