GROUNDWATER USE POTENTIAL FOR IRRIGATED AGRICULTURE IN THE TEESTA BARRAGE PROJECT
MUKHLESUZZAMAN TALUKDER
BUET
March 2012
INSTITUTE OF WATER AND FLOOD MANAGEMENT BANGLADESH UNIVERSITY OF ENGINEERING AND TECHNOLOGY
GROUNDWATER USE POTENTIAL FOR IRRIGATED AGRICULTURE IN THE TEESTA BARRAGE PROJECT
A thesis by Mukhlesuzzaman Talukder
In partial fulfillment of the requirement for the Master of Science in Water Resources Development
BUET
March 2012
INSTITUTE OF WATER AND FLOOD MANAGEMENT BANGLADESH UNIVERSITY OF ENGINEERING AND TECHNOLOGY
The thesis titled ‘Groundwater Use Potential for Irrigated Agriculture in the Teesta Barrage Project’ submitted by Mukhlesuzzaman Talukder, Roll No. M10052810F, Session: October 2005, has been accepted as satisfactory in partial fulfillment of the requirements for the degree of Master of Science in Water Resources Development on March 10, 2012.
BOARD OF EXAMINERS
...... Dr. M Mozzammel Hoque Chairman Professor (Supervisor) Institute of Water and Flood Management Bangladesh University of Engineering and Technology Dhaka
...... Member Dr M. Shahjahan Mondal Associate Professor Institute of Water and Flood Management Bangladesh University of Engineering and Technology Dhaka
...... Member Dr. Md Munsur Rahman (Ex-officio) Professor & Director Institute of Water and Flood Management Bangladesh University of Engineering and Technology Dhaka
...... Member Dr. A.F.M Afzal Hossain, (External) Director, Irrigation Management Division Institute of Water Modelling House No. 496, Road No. 32, New DOHS, Mohakhali, Dhaka
Dedicated to ......
My beloved parents & brother
CANDIDATE’S DECLARATION
It is hereby declared that this thesis or any part of it has not been submitted elsewhere for the award of any degree.
……………………….. Mukhlesuzzaman Talukder
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ACKNOWLEDGEMENT
At first, I would like to thank almighty Allah for giving me the patience to complete the work.
I would like to express my sincere and heartiest gratitude to my supervisor Dr. M Mozzammel Hoque, Professor, Institute of Water and Flood Management, BUET, for his constant guidance, valuable advice, generous help and constructive discussion to carry out this research and writing this manuscript. I consider myself to be proud to have worked with him. I express my profound respect and deepest sense of gratitude to all of my respected teachers of IWFM, BUET for their fruitful advices in different times and valuable teachings under different courses that have helped me reach at this stage.
I am deeply grateful to Dr Iftekarul Alam of BADC, M. A Hashem, Deputy Chief of BWDB, I also thank my beloved friends Engr. Md. Abu Sayed, Engr. Sheikh Jahid, Engr. Mashiur Rahman, Mr. Animes Kumar Gain and Mr. Md. Sanaul Kafi. I remember the help by Ms. Muktarun Islam, Ph.D student of Dr M Mozzammel Hoque of IWFM, BUET for providing support during the thesis work.
I would like to acknowledge my best gratitude to Bangladesh Water Development Board (BWDB), Bangladesh Agricultural Development Corporation (BADC), Department of Agricultural Extension (DAE), Institute of Water Modeling (IWM), for providing data and related information. I acknowledge my Class Mates, Library Assistant and other staffs of IWFM for their kind cooperation.
The author
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ABSTRACT
The study was undertaken in the Teesta Barrage Project (TBP) area. Eight out of total 12 Upazilas under 3 Districts: Nilphamari, Rangpur and Dinajpur are considered for the current study to compare the pre and the post project groundwater conditions, to develop a statistical prediction model for groundwater storage change, to analyze the design surface water availability and to evaluate the prospect of groundwater irrigation in conjunction with the surface water during different cropping seasons. The Teesta Barrage Project went into operation in 1993. Since its implementation the irrigated area of the project has been increasing and the maximum irrigated area of 76000 hectare during Kharif 11 season was achieved in 2005. With the increase in irrigation area the recharge area from irrigated surface water in the project area has increased. It is found that the supplementary irrigation during Kharif II has a significant impact in increasing the groundwater recharge. An analysis was done with the weekly and the yearly maximum and minimum groundwater data within the project area. Similar analysis was done for outside the project area to evaluate the impact of the project on the groundwater system in the project area. It is observed that groundwater level in the project area has been increasing after the project implementation but this has been decreasing outside the project area. Again after project implementation groundwater withdrawal rate is increasing with time for dry season irrigation. This increased rate of withdrawal and the rise of groundwater level is the contribution of the surface water supplied through groundwater recharge. It is further observed that groundwater level has been increased not only through recharging from supplementary irrigation but also direct recharge from the rivers and the local rainfall. In respect of Teesta River flow at the project site it is observed that in the Teesta River at the project area the maximum water is being flowed on August (Kharif -11 season ) and minimum water is being flowed on February (Rabi season). It is observed that the design required quantity surface water flow is available during Kharif-11 season but is very small during Rabi (Boro) season. Historical discharge analysis shows that the Teesta River discharge is decreasing significantly all through the year. From 1990 to 2005 the discharge has decreased by 40% both in Karif II and Rabi seasons and this figure is lower during the Kharif I season. Thus, the decrease in flow of Teesta River has would cause non-availability of water for surface water irrigation and no recharge to the
v groundwater affecting the groundwater irrigation most importantly during the dry season. Therefore, there is potential to increase the groundwater irrigation in conjunction with the surface water during the different cropping seasons provided the flows of Teesta River would be maintained to supply design surface water during Kharif II season and the river water level is always above the groundwater.
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Tables of Contents
Page No.
Acknowledgement iv Abstract v Contents vii List of Tables ix List of Figures ix List of Photos xii List of Abbreviations xiii
CHAPTER 1 INTRODUCTION 1
1.1 Background 1 1.2 Objectives 2
CHAPTER 2 REVIEW OF LITERATURE 3
2.1 Introduction 3 2.2 Groundwater 3 2.3 Groundwater Quality 11
CHAPTER 3 STUDY AREA 12
3.1 Location 12 3.2 River System and Drainage 14 3.3 Canal System 17 3.4 General Characteristics 22 3.5 Topography 22 3.6 Soil Characteristics 23 3.7 Climate 23 3.8 Land Use Pattern 24 3.9 Infrastructure 24
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3.10 Surface Water 25 3.11 Groundwater 25 3.12 Existing Use of Surface and Groundwater 25 3.13 Present Farming System and Cultural Practices 26
CHAPTER 4 METHODOLOGY 27
4.1 Data Collection 27 4.1.1 Groundwater 27 4.1.2 Rainfall 29 4.1.3 River water level 29 4.1.4 Other data 30 4.2 Data Processing 30 4.2.1 Groundwater 30 4.2.2 Rainfall 30 4.2.3 River water level 30 4.2.4 Abstraction and Irrigation 31 4.3 Data Analysis 33
CHAPTER 5 RESULT AND DISCUSSION 35
5.1 Variation of Groundwater Level 35 5.1.1 Weekly variation of groundwater level inside TBP 35 5.1.2 Yearly variation of groundwater level inside TBP 37 5.1.3 Regional variation of groundwater with time 41 5.2 Groundwater Withdrawal 45 5.2.1 Groundwater Withdrawal at Different Months by Different means 46 5.3 River Water Level 48 5.4 Relation between Groundwater Level and River Water Level 50 5.5 Relation between Groundwater Level and Rainfall 52
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5.6 Irrigation Coverage in the Project Area 53 5.7 Variation of Groundwater Level with Groundwater Withdrawal 56 5.7.1 Groundwater level changes inside the project area 56 5.7.2 Groundwater level changes outside the project area 60 5.8 Prediction of Groundwater Level Using Linear Regression Model 61 5.9 Need and Potential for Groundwater Use 63 5.9.1 Availability of surface water 63 5.9.2 Crop production with current conditions 66 5.9.3 Potential of groundwater use in conjunction with surface water 67
CHAPTER 6 CONCLUSIONS 68
REFERENCES 70
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List of Tables
Table Page no
3.1 Phase-wise area and implementation periods of TBP 14 3.2 The Upazilas included in the irrigation facilities through Teesta, Rangpur and Dinajpur canal 17 3.3 The general characteristics of the project area 22 3.4 Infrastructure features of the TBP (Phase) 24 4.1 Observation stations of various types of data 27 4.2 Rainfall gauge stations 29 4.3 River water level stations 29 4.4 Number of tube wells within the study area in 2000 32 4.5 Efficiency and operating hours of pumps 33
List of Figures
Figure Page no
3.1 Bangladesh map showing Teesta Barrage Project 12 3.2 Location of the Teesta Barrage Project (Phase I) 13 3.3 Teesta Barrage Project (Phase I) with river system 16 3.4 Teesta Barrage Project (Phase I) with canal system 18 3.5 Teesta, Rangpur and Dianjpur canal system 19 4.1 Hydrological stations of the project area 28 5.1 Weekly variation of groundwater level at well NIL-05 in Dimla Upazila 36 5.2 Weekly variation of groundwater level at well RA-07 in Rangpur Sadar Upazila 36 5.3 Weekly variation of groundwater level outside of Project at well DIN-29 in Domer Upazila 37
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5.4 Variation of groundwater level with time at well NIL-05 38 5.5 Variation of groundwater level with time at well NIL-20 38 5.6 Variation of groundwater level with time at well NIL-23 39 5.7 Variation of groundwater level with time at well NIL-27 39 5.8 Variation of groundwater level with time at well NIL-25 40 5.9 Variation of groundwater level with time at well RA-03 40 5.10 Variation of groundwater level with time at well RA-07 41 5.11 Variation of groundwater level with time at well DIN-13 41 5.12 Maximum groundwater level contour map for 1992 and 2006 43 5.13 Minimum groundwater level contour map for 1992 and 2006 44 5.14 Withdrawal of groundwater per sq-km 45 5.15 Irrigation withdrawal of groundwater per sq-km 46 5.16 Domestic withdrawal of groundwater per sq-km 46 5.17 Monthlies withdrawal of groundwater by shallow tube well 47 5.18 Monthlies withdrawal of groundwater by deep tube well 47 5.19 Monthlies withdrawal of groundwater by hand pump 48 5.20 Total withdrawal of groundwater by shallow tube well, deep tube well and hand pump 48 5.21 Maximum and minimum river water level at Dalia (SW_291.5R) 49 5.22 Maximum and minimum river water level at Doani (SW_291.5L) 49 5.23 Maximum and minimum river water level at Kaunia (SW_293) 50 5.24 Maximum and minimum river water level at Kharibari (SW_291L) 50 5.25 Groundwater level and water level (pre-project) 51 5.26 Groundwater level and water level (post-project) 51 5.27 Groundwater level at well NIL-05 and rainfall of Dimla in the year 2000 52 5.28 Groundwater level at well NIL-05 and rainfall of Dimla in the year 2005 52 5.29 Irrigable area of Karif-11 and Karif-1 54 5.30 Irrigation coverage by surface water 54 5.31 Gross and irrigable area within the project. 55 5.32 Irrigation coverage by groundwater 55
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5.33 Variation of groundwater level and withdrawal of groundwater with time at well NIL-05 in Dimla Upazila 57 5.34 Variation of groundwater level and withdrawal of groundwater with time at well NIL-20 in Jaldhaka Upazila 57 5.35 Variation of groundwater level and withdrawaddl of groundwater with time at well NIL-23 in Kishoregonj Upazila 58 5.36 Variation of groundwater level and withdrawal of groundwater with time at well NIL-25 in Nilphamary Sadar Upazila 58 5.37 Variation of groundwater level and withdrawal of groundwater with time at well NIL-27 in Saidpur Upazila 59 5.38 Variation of groundwater level and withdrawal of groundwater with time at well RA-07 in Rangpur Sadar Upazila 59 5.39 Variation of groundwater level and withdrawal of groundwater with time at well RA-03 in Gangachara Upazila 60 5.40 Variation of groundwater level and withdrawal of groundwater with time at well DIN-13 in Chirirbandar Upazila 60 5.41 Variation of groundwater level and withdrawal of groundwater with time at well DIN-29 in Domer Upazila 61 5.42 Upazilawise value of coefficient of determination, R2 62 5.43 Impact on groundwater level from various distances to canal and river 63 5.44 Monthly discharges of Teesta during Kharif-I, Kharif-II and Rabi season 64 5.45 Monthly discharges of Teesta during Kharif-I 64 5.46 Monthly discharges of Teesta during Rabi season 65 5.47 Upazilawise crop yield and production of pre-project and post-project. 66 5.48 Upazilawise % increase crop yield and production 66
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List of Photos
Photo Page no
3.1 Dinajpur canal with flow 20 3.2 Teesta water can reach at the tail end of Dinajpur canal system 20 3.3 Field canal 21 3.4 Irrigation canal used in the dry season 21
xiii
List of Abbreviations
ADB Asian Development Bank BWDB Bangladesh Water Development Board BADC Bangladesh Agricultural Development Corporation DAE Department of Agricultural Extension DTW Deep Tube well DSSTW Deep Set Shallow Tube well FAO Food and Agricultural Organization GWT Groundwater Table HYV High Yielding Variety IWM Institute of Water Modeling MPO Master Plan Organization MWR Ministry of Water Resources NWMP National Water Management Plan NM1DP National Minor Irrigation Development Project NMIC National Minor Irrigation Census PWD Public Works Department STW Shallow Tube well SWMC Surface Water Modeling Centre TBP Teesta Barrage Project UNDP United Nations Development Programmed VDSSTW Very Deep Set Shallow Tube well
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CHAPTER 1
INTRODUCTION
1.1 Background Bangladesh is a country of agro-based economy. It has more than 300 rivers, tributaries and distributaries. Still a vast area of North Bangladesh suffers from scarcity of water for irrigation its agricultural lands, not only in dry months but also during monsoon when a prolonged spell of scarcity/no rainfall affect crops. Also the soil of the project area is sandy. So the importance of irrigation facility was realized. The idea of irrigation from the Teesta River was conceived since British time. Most of the area found suitable for gravity irrigation, falls in Bangladesh. Due to partition of India, implementation of the project was slowed down. However, both the countries started to formulate projects on the Teesta River in their own perimeters.
Teesta Barrage Project (TBP) in the North-West region of the country was initiated with the objective of increasing the agricultural production through supplementary irrigation during Kharif II (BWDB, 2005a). Agriculture is central to the economy and society of the project area and it has been observed that the TBP has considerable and huge potential for expanded grain production and economic activities (BWDB, 2005a). Agriculture is the main source of income generation for reducing poverty. Benefits of the project have been realized mainly through the increased agricultural production The Project has a gross area of 750,000 ha of which 540,000 ha are irrigable. The Phase I of the project has a net irrigable area of 111,406 ha of which 91,226 ha has been gradually brought under operation since 1993. From the beginning of operation the surface irrigation has been also provided to a limited extent during Kharif 1 in addition to Kharif 11(IWM, 2003).
Surface water availability from the Teesta Barrage (BWDB, 2005b) is enough to meet the design irrigation requirement for Phase I and Phase II during Kharif II season. But the flow is not abundant during Kharif 1 and is very limited during the Boro season (BWDB, 2005b). The recently commissioned Barrage (Hoque and Islam, 2000) on the Indian side of Teesta River has developed a concern of dependency of the project on groundwater irrigation not only for Boro season but for Kharif I and eventually for Kharif II. ADB (1992) recommended the year round sustainable irrigation through conjunctive use of
1 surface water and groundwater for increasing food production. The National Water Management Plan (NWMP) of Bangladesh (MWR, 1999) emphasizes on the use of groundwater and surface water conjunctively to increase the water use efficiency. The NWMP of Bangladesh (MWR, 2001) support of private development of groundwater irrigation for promoting agriculture growth will continue, where surface water is limited.
In the project area the groundwater has been currently withdrawn for boro at the increasing rate mostly by shallow tube well (STW). Hand tube wells (HTW) and a limited number of deep tube wells (DTW) are also used for groundwater withdrawal. A study (SWMC, 2002) reports the availability of groundwater in the project area for the year 1999.For year round future irrigation requirement further potential of groundwater availability needs to be explored. The present study will be an academic exercise in this effort.
1.2 Objectives The overall objective of the study is to evaluate the groundwater irrigation potential and Agriculture in the Teesta Barrage Project.
The specific objectives of the study are as follows:
To evaluate pre and post project groundwater conditions.
To develop a statistical prediction model for groundwater storage changes.
To evaluate the prospect of groundwater irrigation in conjunction with the Surface water during different cropping seasons.
2 CHAPTER 2
LITERATURE REVIEW
2.1 Introduction Groundwater which occurs beneath the water table within the subsurface geologic formations is an important source of water resources. In this Bangladesh groundwater generally occurs under the water table (unconfined) conditions, but in some areas groundwater is found under semi-confined or confined conditions. Many parts of the world depend on groundwater as their source of water supply for domestic and industrial uses. The other major sector of groundwater utilization is the irrigation of agricultural lands during dry seasons. It is generally utilized where irrigation from surface sources is difficult or impossible and other water demand is high.
In Bangladesh, groundwater development has become popular in the sectors of agricultural production and public supplies. Although average rainfall in this country is very high of about 232 cm (MPO, 1985) irrigation is of critical importance during half of the year from October to May. During these months irrigation from surface source is not practically available in most cases due to scarcity of water in the rivers. Therefore, the use of groundwater has become increasingly an important source of irrigation during dry season. In addition, over 90% of the population of Bangladesh relies upon groundwater for its potable water supplies.
2.2 Groundwater Groundwater is one of the major national resources of Bangladesh. It has been developed advantageously as a source of irrigation, domestic and industrial supplies. GW has become an increasingly important water source for irrigation over the last two decades. It is also the source of potable water supply for about 95% of the population of the country (MPO, 1991).
3 Khan (1988) mentioned that in Bangladesh groundwater has been developed extensively for irrigation and public supplies without consideration of the possible after-effects. The abstraction of groundwater for agricultural development and public supplies has already brought a degradation of the' natural hydrological regime in many areas. As a result, environmental conditions have deteriorated in these areas particularly in the northern regions. The possible environmental, consequences of groundwater abstraction in this country are decline of groundwater levels, degradation of groundwater quality, pollution and health hazard, reduction in river flows, conflict among trade-offs, etc.
Temporary overdraft conditions usually occur in many areas during dry season due to hydrological droughts as well as extensive utilization of groundwater. Due to such declination of groundwater levels most of the STWs and HTWs almost rap dry. Furthermore, about 50,000 ponds, tanks and ditches within Barind areas have almost dried up (Khan, 1988). Decline in water levels of these local water bodies has been due to the - interaction of pumping groundwater from the adjacent shallow aquifers and evaporation losses. During dry months the Barind region is facing acute shortage of water for irrigation, drinking and fish culture which ultimately has emerged as a threat to the environment. Large decline in groundwater levels have been experienced in an increasing number of localities within the north west and south west regions of the country.
Surface Water Modeling Centre (SWMC) had been engaged to carryout irrigation, Drainage and groundwater studies and to develop decision Support System for irrigation management in Teesta Barrage Project (TBP) Phase-1. Groundwater modeling study is one of the study components to assess the groundwater availability and to examine the recharge characteristics of the aquifer. An integrated river and aquifer modeling approach had been applied using MIKE11-MIKE SHE coupled modeling system.
Conjunctive management of surface water and groundwater resources is emerging as a major water management strategy in recent years. The subsurface seepage from the farmlands during their irrigation period would be transmitted to aquifers through watershed development structures constructed across farmlands and proper lands .These
4 structures control the water course/stream and help improve groundwater recharge in canal irrigation years end rainy seasons in the adjoining non-water receiving command area. This recharged groundwater resource in non-canal years could be assessed as received through wells.
The main focus of the study is a sustainability of groundwater recharge through watershed development structures in a canal irrigation system by changing the rules of water delivery. The results indicated that watershed development structures had been come more powerful once the alternative sluice irrigation system was introduce in the watershed area.
Hoque and Islam (2000) conducted a study on conjunctive use of groundwater and surface water for irrigation in Buri-Teesta Irrigation Project. In the study groundwater and surface water availability of project was assessed, groundwater recharge from rainfall and rivers was evaluated and finally a conjunctive use plan was formulated. The study found that the availability of surface water is inadequate to meet the project irrigation requirement. It is also found that the dependability of groundwater and river water decrease with the distance between the project area and the river. Ultimately these alternative schedules for seasonal irrigation supply from g groundwater and surface water conjunctively had been formulated.
Many studies have been conducted world wide and some in Bangladesh on groundwater availability. An attempt is made here to review the most relevant studies.
In the MPO study the country has been divided into four physiographic units. The potential recharge, which has been defined as the mean annual volume of surface water that could reach the aquifer, limited only by the rate of percolation of topsoil or subsoil, was first calculated. Potential recharge is the sum of actual recharge to the aquifer and rejected recharge. Rejected recharge is that fraction of water available at the surface which can not infiltrate because the water table is at the surface. Actual recharge can thus
5 be increased to approach the potential recharge by lowering the water levels by pumping during the dry season.
The conceptual basis and the methodology of the recharge model developed by the MPO are valid and appropriate but reservations have been expressed about the parameters and data base used in the model. The MPO has pointed out that there are deficiencies in data as groundwater level, volume of water use, and vertical groundwater flow. Only a few proper bore logs were available from BWDB's groundwater circle that could be used for determination of correct aquifer properties.
MPO (1987) estimated that available recharge ranged from about 100 mm to over 500 mm. Lowest values of 100 mm or less occurred in the western south-west region. Highest values (over 500 mm) occurred in the lighter textured soil areas of Thakurgaon and Rangpur, at the confluence of the Jamuna and old Brahmaputra, and in the deeply flooded piedmont foot areas of the north-west region.
MPO Study (1987): Under National Water Plan (1985-2005), MPO studied groundwater resource of Bangladesh with emphasis on groundwater recharge assessment (MPO, 1987). The study also provides mainly with a national assessment of the volume of groundwater available for development, quantity and zoning of required pump and their types to utilize the groundwater resource, effects of groundwater development on seasonal depletion and factors constraining groundwater development. Eight four layer multiple cell integrated finite difference models, dispersed over Bangladesh were developed to establish calibrated and verified rates of vertical recharge to ground water. Depending on availability of data other catchments were modeled as a multiple single eel! mode) in which only the vertical components of flow were considered. For Northwest region, potential, usable and available recharge was found as 592 mm, 444 mm and 325 mm respectively. According to the MPO study the present area falls under the zones where full development of groundwater could be, possible by suction mode tube wells (DSSTW) and force mode pumps or by force mode tube wells (DTW) and suction mode pumps.
6
SWMC Study (1996): The MIKE-SHE modeling system was introduced by IWM in mid-1996 in order to model the interaction between the surface and groundwater. As part of the transfer of this technology by IWM, a pilot integrated model was established for the Jamuneswari basin in the north of the Northwest Region (SWMC, 1996). The model was calibrated against groundwater level of a set of observation well data covering the period of 1986 to 1994. The results of the model calibration were promising considering the lack of data in some areas and the short time available for actual calibration. The model reproduced the groundwater levels and surface water flows well, and clearly showed the interaction between surface water and groundwater.
SWMC Study (2000): IWM has carried out an integrated surface water groundwater model study in the Atrai basin of northwest Bangladesh under the project National Water Management Plan (NWMP) (SWMC, 2000). The model is based on entire land based hydrological cycle. It includes the condition of flow in the river, in the unsaturated and saturated zones of the subsurface together with rainfall, overland flow and evapotranspiration. It is found from the study that the river is in direct contact with the aquifer. The remarkable characteristic in the river-aquifer interaction of the area is that the river contributes much more than that of aquifer but insignificant compared to the actual recharge. It was also found that floodwater has contribution to the recharge of the aquifer.
To increase the water availability in the TBP and to reduce the land acquisition requirement for canal construction, Saleh et. al. (1991) assessed the seepage loss in the project area and then recommended a feasible and cost effective lining for reducing the seepage loss. They found that the average seepage rate of the soils in the project area varied from 0.5m/day to 1.00 m/day. Considering the economic feasibility, Saleh et. al. (1991) concluded that cast in situ concrete lining is the most cost effective lining thus; they recommended it for applying in the Teesta Barrage Project.
7 Wahid (2003) observed that groundwater development and utilization for dry season irrigation in the TBP area by farmers has led to near-unrestricted exploitation of the resource in the recent past, which necessitates a comprehensive effort to assess the available groundwater resource and its development potential. He noticed that groundwater-use potential varies considerably from Thana to Thana over the TBP area and the overall increase in groundwater-use potential in the TBP area is due to good prospects in a few Thanas only. He recommended zoning of the TBP area into different groundwater management classes based on use potential.
Alam and Kabir (2004) pointed out that India's National Perspective Plan of 1980 proposes to develop projects for Inter-basin water transfer by linking rivers with a massive canal system. They concluded that when implemented, this plan would cut down the flow of the rivers that flow into Bangladesh. This will adversely affect agricultural production, fishery, ecology, navigation, and bio-diversity. They revealed that reduction of flow of the Teesta and other rivers in the NW region would adversely affect the agriculture, groundwater resource, navigation, industry, wetlands, and forestry in the NW region.
IWM (2004) made a detailed study on command area development of the Teesta Barrage Project, and articulated that due to scarcity of water in the Teesta River during dry period, farmers have to rely mostly on groundwater, which is costly and in some areas of the project, the groundwater level is nearly at mining state. In some areas, hand tubewell goes out of order due to lowering of groundwater level. IWM (2004) reiterated that the Teesta Barrage Project has been planned and implemented to provide primarily supplementary irrigation for transplanted Aman. The observation of the institute is that the cropping pattern and cropping intensity have changed remarkably in the irrigated area. Farmers have started to grow HYV Aman rice and at least two crops are grown in the irrigated area. After implementation of the TBP, the irrigation coverage has been increasing gradually.
8 Islam and Akmam (2007) studied the changes in socio-economic and environmental situations in the TBP during 2000-2007. In their study, they highlighted changes in socio- economic and environmental situations in the Dalia irrigation project (actually the TBP) area during 2000-2007. They carried out a socio-economic survey in 2000. In 2007, they carried out another follow-up survey in the same area. Based on a social survey, they pointed out that although the average yearly income in the project area increased by about 151%, dependency on agriculture decreased from 63% to 53% with no change in the cropping intensity. They found that some improvements have occurred among the inhabitants regarding education, housing, health, and sanitation.
IMED (2008) an evaluation study of the TBP was carried out by IMED of the Ministry of Planning and it was reported that in TBP, the single cropped area reduced by 100%, double-cropped area comprised of 84% and triple-cropped area comprised of 16% of the total cropped area. Cropping intensity increased to 233% in the year 2007. HYV Aman area increased in comparison to Local variety (LV) after intervention of TBP. HYV Aman area was increased by 45% whereas there has been a 54.8% decrease in local variety (LV) of Aman crop areas. Aman crop annual production significantly increased in all Upazilas under study area. It was clear that the reasons of increased crop production are due to introduction of HYV crop and TBP water as well as flood control. The mean monthly family income, before and after the project, has registered an increment of 73% and the benefit of increased income has been obtained by people belonging to poor and lower middle class. The study reported that there is scarcity of water during the dry season and only about 30% of the Kharif- II season irrigated area can come under irrigation during the Kharif-I (late Boro / early Aus) season.
Rahman, M. M (2008) in his study on the impact of climate change on command area development of TBP found out that due to the climate change the crop water requirement for T. Aman in TBP would increase in the future projections (2025 to 2050) from that of the base line period (1990). From the analysis of rainfall data, he noticed that due to the climate change the amount of rainfall during the T. Aman season would decrease or increase depending upon the type of model used. During the critical period of crop
9 growth (October), the monthly average rainfall may decrease. He moreover noticed that due to climate change the future flow of the Teesta River at Dalia would also decrease during the critical period of October compared to the observed baseline condition. Therefore, he predicted that during the entire critical period of October, the TBP might face problem to meet the future water requirement due to unavailability of sufficient flow in the Teesta River.
Hossain (2010) discussed the benefits of using the modelling tools for optimum utilization of water resources in irrigation and drainage management of command area development projects. In the Teesta Barrage Project (TBP), he observed that during Kharif-II season, the full supply levels (FSL) could not be achieved in a dynamic head for the required water flow in both the Teesta and the Rangpur main canals. He found, the reason behind this is that these canals were designed for larger flow to cover the areas of both phases (Phase-I & II). FSL was also not achieved during Rabi and Kharif-I as the water flow was not optimal in the Teesta. After modelling study he stated that to achieve FSL and required flow in the canal system, some interventions are required. TBP phase-I is now flood free and the annual return from paddy in that area is about Tk. 300.0 crore. He concluded that the effectiveness of the modelling tool has proven to be convenient as well as an asset for assessing quantitative measures.
Higano et al. (undated) worked on rural poverty alleviation through large-scale irrigation planning and observed that due to the operation of the Gazoldoba Barrage (India), the water flow of the Teesta River decreased significantly, threatening the Teesta Irrigation Project. Exclusive control of Teesta's water in the dry season and sudden release of excessive water through the barrage (India) in the rainy season lead to serious sufferings of the people in the Bangladesh area of the basin. Finally they propose some remedial measures to solve the problem of sharing of the Teesta water, especially during the dry season between India and Bangladesh (like establishment of basin-wise sharing criteria, storing of monsoon flow etc.) and also some other proposals regarding water management and control during rainy season (integrated water management).
10 2.3 Groundwater Quality The quality of groundwater is an important consideration for successful tube well irrigation. Generally, four types of problems are encountered with the irrigation water These are - i) Salinity -when the total quantity of salts in the groundwater is high enough to accumulate in the crop root zone that reduces crop yield. ii) Permeability - due to presence or absence of some specific salts in water that reduces soil infiltration rate. iii) Toxicity - one or more specific ions in water, namely boron chloride and sodium that are taken up by the crop and accumulate in amount that in reduced yield, and iv) Miscellaneous - various other problems related to irrigation water quality.
The quality of groundwater in Bangladesh is generally good for all purposes except in the coastal zone where the shallow aquifers are highly saline (MPO, 1987). Application of fertilizers and pesticides on agricultural lands can add these materials to the groundwater through leaching and percolation. Groundwater quality could be affected in the future by over drafting, increase in saline water intrusion, and introduction of manmade pollutants.
It has been observed that since the start of surface water irrigation in 1993, the surface water irrigation coverage varies from 5400 ha in 1993 to 20,000 ha in 1997, which shows the limited potential of surface water surface water irrigation during dry season .Wet season coverage is 57,000 ha during 2001. In reality extensive groundwater abstraction is in practice to meet the irrigation demand during dry season. Abstraction of groundwater is mainly done by shallow tube wells. The present agricultural practice has widely been changed from the conceived during project planning and people are now growing High Yielding Variety (HYV) rice during dry period.
11 CHAPTER 3
STUDY AREA
3.1 Location The Teesta Barrage Project, the largest irrigation project of Bangladesh, is located in the Northwest region of the country. The location of the study area is shown in following map. The project is bounded by the Teesta on the North, the Atrai on the West, Shantahar-Bogra Railway line on the South and Bogra-Kaunia Railway on the East. It has been planned for Irrigation, Flood Control and Drainage for a gross area of 750,000 ha of which 540,000 ha are irrigable. The project covers seven districts of North Bangladesh. Project Location CAD for Teesta Barrage Project
Teesta Barrage Project
B a y o f B e n g a l SWMC
Figure 3.1: Bangladesh map showing Teesta Barrage Project.
12 Project Area Project
Figure 3.2: Location of the Teesta Barrage Project: Phase I
13 To derive early benefits, the project has been phased out, viz. Phase-I and Phase-II. The Phase-I of the project has a gross area of 154,250 ha and net irrigable area of 111,406 ha. The study area is the Teesta Barrase Prorject: Phase-1 that covers 12 Upazillas of Rangpur, Nilphamari and Dinazpur Districts. These Upazilas are Rangpur Sadar, Taragonj, Badarganj, Gangachara, Dinajpur sadar Khansama, Chirirbandar, Parbatipur, Nilphamari sadar, Kishoreganj, Jaldhaka, Dimla, Saidpur.
Table 3.1: Phase-wise area and implementation periods of TBP Phase Gross Area Net Implementation Remarks (ha) Irrigable Period Area (ha) Phase I 154,250 91,226 1984- 1998 Fully completed Source: BWDB, 2006
The main objective of the project is to provide supplementary irrigation to a net area of 111406 ha in phases under gravity irrigation system through the irrigation network of TBP Phase-I. This will save the Transplanted Aman Crops from damages due either to occasional drought & dry spell or shortage of adequate water for rice plants to mature.
3.2 River System and Drainage TBP has been implanted to ensure Kharif-II rice in a flood free environment. Natural river systems serve the drainage of the project. The rivers are (1) Buriteesta - Naotare - Dhum System, ( 2) Aulikhana-Ghagot System, ( 3) Deonai - Charalkata -Jamuneswari System, and
( 4) Dhaijan -Bullai -Jamuneswari System.
These river systems drain the runoff from both within and outside the project area (often caused by flooding from across India due to breach of the Teesta embankment). The aforesaid runoff together with that produced from the irrigation which will be mainly of supplemental application of Kharif-II crops during the monsoon months will have to be drained efficiently by the natural drainage system. After implementation of the project a large number of roads have been developed inside the project area; homestead area has also increased considerably. The new road network and canal dykes interrupt the natural
14 overland drainage pattern. The design drainage area of the drainage structures have been changed with the new interventions and in most cases drainage structures drain more area than that of design and structures are now inadequate for drainage. The drainage may pose a big problem due to the consequent influence of the already high ground water table in the monsoon. Also local people cut main, secondary and tertiary irrigation canals in a number of locations to get relief from drainage congestions, which also hampers irrigation.
15
Figure 3.3: Teesta Barrage Project: Phase I with river system (Source: IWM)
16 3.3 Canal System The main canal systems of the Teesta Barrage Project consist of the following four main canals: i) Teesta main canal ii) Dinajpur major secondary canal iii) Rangpur major secondary canal, and iv) Bogra major secondary canal
The Teesta main canal Dinajpur major secondary canal and Rangpur major secondary canal provide irrigation facilities in the project area.
Table 3.2: The Upazilas under irrigation facilities of Teesta, Rangpur and Dianjpur canals Teesta canal Rangpur canal Dinajpur canal
Dimla Badarganj Chirir bander Gangachara Gangachara Jaldhaka Jaldhaka Jaldhaka Kishoregonj Kishoreganj Kishoregonj Nilphamari Rangpur Nilphamari Saidpur Nilphamari Rangpur Parbotipur Saidpur Taragonj
17
Figure 3.4: Teesta Barrage Project: Phase I with canal system (Source: IWM)
18
CAD for Teesta Barrage Project Project Features
Irrigation System & Command area
Gross Benefited Area 748990 ha ( Phase I & II)
Irrigable Area Teesta Canal 540486ha (Phase I & II) System
Gross Benefited Area
154250ha ( Phase I) Dinajpur Caanal Irrigable Area System 111406ha (Phase I) Rangpur Canal System
Figure 3.5: Teesta, Rangpur and Dianjpur canal system
TBP (phase-I) was planned and implemented primarily to ensure transplanted Aman (Kharif-II) in a flood free environment providing supplementary irrigation to a net area of 111406 ha in phases under gravity irrigation system through the irrigation network of TBP Phase-I. Following the inception of the Teesta Barrage Project, it soon became clear that the performance of the project is not properly matching the anticipated level. It had been realized by overall efficiencies of the canal system during irrigation in the last few years. To provide adequate and equitable supplies of irrigation water, there was a strong need for improved performance of the main, secondary and tertiary canals.
19
Photo 3.1: Dinajpur canal with full flow
Photo 3.2: Tail end of Dinajpur canal system
20
Photo 3.3: Field canal
Photo 3.4: Irrigation canal used in the dry season
21 The main irrigation canals were designed to provide irrigation to a larger area than the present irrigable area of TBP, Phase-I .The dynamic head was considered to feed water from main to secondary and secondary to tertiary canals. Irrigation has been proving since 1993, but irrigated area was much less than that of phase-I. Obviously, the canals were operated with lower flow than the designed one and as a result dynamic heads were not achieved in the canals. Farmers and irrigation managers experienced some other problems related to irrigation. Some of the secondary and tertiary canals do not get adequate flow and required Full Supply Level (FSL).
3.4 General Characteristics The general characteristics of the project area are presented in Table 3.3.
Table 3.3: The general characteristics of the project area Component Characteristics Topography 55. 16 m to 29.8 m (PWD) Rainfall 2341 mm/year based on data of fourteen local stations for the period 1993-2000 Evaporation 1182 mm/year based on data of four locations for the period 1993-2000; 2-7mm/day Groundwater Level In general peak level (monsoon) is 0.5m to1m below ground surface; a fluctuation is 2m to 4m Soil Texture Valium to coarse sand Geology Young gravely sand Specific Yield 0.03-0.3 Land Use Agriculture Agriculture Paddy (Boro, HYV-Aman), Tobacco Irrigation Supplementary irrigation by surface water; dry season Irrigation- mainly by groundwater Abstraction STW and DTW (mainly by STW)
3.5. Topography The topography of the area varies from 56 m to 29 m PWD. The land elevation gradually lowers from northwest to southeast. The slope is 45 cm per 1 km.
22 3.6 Soil Characteristics According to the study of IWM (2003) soil samples of 12 locations have been collected from different parts of Teesta Barrage Project of Phase-I. The results indicate that the soils are of heterogeneous nature having wide variations in their texture and hydraulic properties. The soils can generally be termed as medium to coarse textured. Most of the soils (classified as medium-textured) are either having a top or bottom impermeable layer. The hydraulic conductivity values obtained for the soils at different depths are typical of medium textured soils (0.36-3.6 cm/hr). The infiltration capacity of the soils are at plough layer varied between 0.3 and 5.7 cm/hr (slow-moderate), which is also typical of medium to coarse textured soils. Soil texture varies between silt, silt loam, sandy silt, sandy loam and loamy sandy.
3.7 Climate The area has got the significant increase in annual average rainfall and reduced diurnal temperature fluctuations. The randomness characteristics of rainfall and temperature do not allow, us to relate the project effect, but it is noticed by the inhabitants that, the project has been brought out a good positive impact on climatic point of view. It was heard that, once the area experienced hot winds in association with sands had been blown from the west in the summer season. But after the implementation of the project, the condition was drastically changed to gentle soft breeze, nice to feel. The annual rainfall in the project area is varied.
23 3.8 Land Use Pattern Land use pattern of the project area has been changed slightly. Available database reveals that the proportion of cultivated land has been increased.
3.9 Infrastructure For achievement of the project purpose, various types of physical infrastructure were implemented. The infrastructures of the project area listed in Table 3.4. Table 3.4: Infrastructure features of the TBP: Phase 1 Sl Items Unit Total Phase-I Phase-I No. project (No./Length) (No./Length) 1 Barrage(615M) - 1 1 1(Restructured) 2 Canal Head Regulator (110M) - - 1 - (No./Lenth) 3 Closure Dam (2470M) - 1 - - (No./Lenth) 4 Flood By-pass (6 10M) - 1 - -
5 Flood Embankment Km 80 80 80+Bank protection
6 Main Canal Km 34 34 33.67(1 item) 7 Major Secondary Canal Km 275 120 74.85 (Rangpur-Bogra & Dinajpur) 8 Secondary Canal Km 1450 360 215.24
9 Tertiary Canal Km 2720 590 325.24 10 Drainage Channel Km 5000 960 250.00 11 Irrigation Structures - 1512 391 110 1112 Drainage Structures - 2320 635 50 13 Silt Trap (45 ha.) - 1 1 1 14 Turn Out - 15000 5000 2000
24 3.10 Surface Water TBP, Phase-1 is now free from flood of Teesta River. The project has brought out positive impacts as per the surface water concern. The project area had a little or no access to the fresh surface water in the critical dry months (March & April). The water quality of the canals are considered as very good in terms of Dissolve Oxygen (DO), Biochemical Oxygen Demand (BOD), PH, total coliform and Temperature. Limited database do not allow to comments about the drainage water discharged. The fresh water on some of the pockets of the project area is facing water logging problem. In such areas the Total count deserves to be taken under keen attention.
3.11 Groundwater The groundwater level was high enough in the flood plain area. Groundwater level is not very far from the surface. During the wet season the depth to groundwater level varies from 0.5m to 1 m in general. In few cases it varies from 2m to 3m (IWM, 2004). The canals were aligned through permeable flood plain soils. The underground irrigation to the flood plain area through the tube wells would maintain the groundwater level. But it has been done oppositely. The gravity irrigation in the sandy flood plain soils leads to rise the groundwater level, as the percolation rate is high enough. Deep percolation ranges from 2-5 mm/day (IWM, 2004). The horizontal seepage water finds its way to lower region as the area has a general surface slope. The dual effects of horizontal seepage and vertical rise of ground water level in some of the area have been facing serious problem. This fatal information comes from the group discussions at Chengmari Village of Moddha Rajib under the Kishoreganj Upazilla of Nilphamari district. Farmers sold their mud from the land adjacent to the canals required to construct the canal dyke. This hasty practice lowered the land surface elevation compared to the surroundings and blockage of flow due to construction of irrigation channel. This ultimately made the opportunity of water logging. There is no complaint about the presence of Arsenic content in groundwater.
3.12 Existing Use of Surface and Groundwater An extensive irrigation canal system has been established in the project area to provide supplemental irrigation during the Kharif II season. The present practice is to grow mainly HYV boro during dry season. Surface water irrigation during dry season is mainly dependent on availability of flow in Teesta River. It has been observed that since the start
25 of surface water irrigation in 1993, the surface water irrigation coverage varies from 5400 ha in 1993 to 20,000 ha in 1997, which shows the limited potential of surface water irrigation during dry season. Wet season coverage is 57,000 ha during 2001. In reality extensive groundwater abstraction is in practice to meet the irrigation demand of boro crop during dry season. Abstraction of groundwater is mainly done by shallow and deep tube wells.
3.13 Present Farming System and Cultural Practices The cultural practices of different crops are dependent on crop calendar. Crop year mainly divided into two seasons- Rabi and Kharif again Kharif has been subdivided into Kharif - I and Kharif –II. Rabi season starts from mid October and ends in mid March while Kharif -I season spread from mid March to mid July and Kharif –II is within the span of time from mid July to mid October. The agro- environmental situation of different season not only influences the farming system and cultural practices but also production is greatly influenced by the cropping season.
The Kharif season is characterized by high temperature, high rainfall, high humidity, high solar radiations and high evaporation. Aus HYV, T. Aman HYV, T.Aman LV, Jute, summer vegetables etc. are mainly grown in this season. The Rabi season is characterized by scanty rainfall, low humidity, low temperature, and lower solar radiation. The crops those need less moisture, tolerant to drought condition, such as wheat, pulses, oil seeds, onion, chilies, W. Vegetables etc. are grown in this season. During Rabi season Boro HYV with high water requirement is grown under irrigation. Crop production needs various agricultural practices to get good harvest and timely cultural operations increase the yield.
26 CHAPTER 4
METHODOLOGY
4.1 Data Collection The major data required for the present study are groundwater level, rainfall, river water level, cropping pattern, crop parameters, and climatic factors, hydro-geological characteristics of the aquifer, recharge, groundwater withdrawal and the project maps. These data have been collected mainly from the secondary sources, such as Bangladesh Water Development Board (BWDB), Local Government Engineering Department (LGED), Institute of Water and Flood Management (IWFM) and the Teesta Barrage Project Office.
4.1.1 Groundwater Groundwater data comprises the groundwater level data from the observation wells. The groundwater level data for the selected observation wells within and adjacent to the project areas have been collected from Groundwater Hydrology Directorate of Bangladesh Water Development Board. The observation wells, their locations and the period for which data collected have been shown in Table 4.1. The observation wells have been selected considering the quality, density of groundwater (observations wells)and other data outside and river side of project area.
Table 4.1: Observation stations of various types of data Types of data Selected station Period Years of data Groundwater NIL005,NIL020,NIL023,NIL025 1990-2006 16 level NIL027,RAN003,RAN004,RAN007 DIN013, DIN028 Rainfall R-167, R-154, R-210, R-177, R-206 1990-2006 16
River water level SW-291.5R (Dalia), SW-291.5L 1990-2006 16 (Doani), SW-293 (Kaligonj), SW-291L (Kharibari/Uttar) River discharge SW-291.5R (Dalia ) 1990-2006 16 (Teesta river)
27
Figure 4.1: Hydrological stations of the project area (Source: IWM)
28 4.1.2 Rainfall For present study, five rainfall stations have been selected from adjacent areas of the study area. These stations are R-167, R-154, R-210, and R-177 and located in the thanas Dimla, Kishorganj, Saidpur, and Kaliganj, respectively. These stations are shown in Map 4.1. The rainfall data have been also collected from Groundwater Hydrology Directorate of BWDB, the details are given in Table 4.2.
Table 4.2: Rainfall gauge stations Sl.No. Thana Station No Year
1. Dimla R-167 1990-2006
2. Kishoregonj R-154 1990-2006
3. Saidpur R-210 1990-2006
4. Jaldhaka R-177 1990-2006
5 Rangpur R-206 1990-2000
4.1.3 River water level The river water level data have been collected from BWDB for stations SW-291.5R, SW- 291.5L, SW-293 and SW-291L. The stations SW-291.5R and SW-291.5L are located at Dalia and Doani respectively, on the River Teesta and the station SW-293 and SW-291L are located at Kaligonj and Kharibari. The details of the data are given in Table 4.3.
Table 4.3: River water level stations SI. No. Station Station No River Year
1. Dalia SW-291. 5R Teesta 1990-2006
2. Doani SW-291. 5L Teesta 1990-2006
3. Kaligonj SW-293 Teesta 1990-2006
4 Kharibari/Utt SW-291L Teesta 1990-2006 ar
29
4.1.4 Other data The required maps, such as, the Nilphamari District map and the Thana maps for Jaldhaka, Kishoregonj, and Dimla have been collected from the Local Government Engineering Department. Maps on groundwater survey and investigation in Bangladesh, Teesta Irrigation Scheme Index map, and the completed Teesta Irrigation Project Index map have been collected from the Groundwater Hydrology Directorate and the Nilphamari Water Development Division of BWDB.
4.2 Data Processing The data collected described in the earlier sections have been transferred from the hard copy to the data base of the project
4.2.1 Groundwater The groundwater data collected have been plotted with time for each year to see the consistency, accuracy and to fill out the gaps where necessary. The data was then corrected for any abnormality observed by smoothing with the preceding and the following data. For example, the plots of groundwater level at six observations wells of Nilphamari District for the year 1992. The plots for the wells, NIL023, NIL027 are not smooth. It is observed that some data are missing and some are abnormally high or low. The unrealistic and the missing data have been corrected and filled out by the nearest average values and the line drawn subsequently adding the corrected data are smooth and continuous the plots of the corrected data. These corrected data have been used for subsequent analysis.
4.2.2 Rainfall The collected data have been processed to see the consistency and accuracy of the data and to fill out the missing data, if there is any.
4.2.3 River water level The river water level data collected have been plotted with time for each year to see the consistency, accuracy and to fill out the gaps where necessary. The data was then corrected for any abnormality observed by smoothing with the preceding and the following data.
30
4.2.4 Abstraction and irrigation There is extensive abstraction of groundwater in the study area mainly by shallow tube well (STW) and deep tube well (DTW). A few number of Deep-set shallow tube well (DSSTW) and very deep-set shallow tube well (VDSSTW) are also found in the study area which are considered as STW in the present study. The main purpose of tube well water abstraction is irrigation during dry season (January-April). The detail information about the tube wells is not readily available. However, NM1DP has organized the total number of each tube well type on Thana basis under National Minor Irrigation Census. SWMC has collected the data from WARPO. Data for the year 1999 has been collected from DAE. Data for the year 1998 and 2000 were not available. From the year 1995 to 1999, the average yearly increase rate of STW was found be 16%. It has been also analyzed that about 80% of net cultivable area were developed for irrigation during the year 1999. Therefore, 1997 and 1999 data was used for the year 1998 and 2000, applying 16% and 5% increase rate on STW. Number of DTW of the year 1994 is not available and 1993 data were used instead. For thanas, which partly covered the model area, the number of tube wells has been reduced proportionately. Table 4.4 shows the number of tube wells within the study area in 2000. The locations of abstraction wells are important. The available data do not support a spatially distributed description.
31 Table 4.4: Number of tube wells within the study area in 2000 Area of Area of Upazila Area of land Upazila which is Number of Tube Sl. Upazila within included Wells No. Project in the project Sq.km % Sq.km STW DTW 1 Dimla 326.80 30 977 2 98.04 2 Jaldhaka 303.52 80 242.816 1897 8 3 Kishoregonj 264.98 100 264.98 3478 6 4 Nilphamari 373.09 50 2098 30 sadar 186.545 5 Saidpur 121.68 100 121.68 1708 16 6 Rangpur sadar 303.33 45 136.4985 2500 18 7 Badargonj 301.29 25 75.645 2002 48 8 Taragonj 201.02 50 100.5 2098 10 9 Gangachara 209.61 65 136.2465 2150 10 10 Chirirbandar 308.68 25 77.17 1039 18 11 Parbatipur 395.1 30 118.53 1946 30
12 Khansama 179.72 12 21.5664 235 3 Source: Field Office of DAE
The daily pumping hour and the efficiency of the pump are not available. During the study on Jamuneswari basin (SWMC, 1996), an average pump operation (Table 4.5) has been derived after discussions with DAE Nilphamari, DAE Dinajpur and BADC Rangpur. The daily pumping hour and the efficiency of the hand pump are not available but during the study it has been derived after discussions with DPH (Department of Public Health Engineering). Generally the capacity of pump for DTW, STW and Hand Pump are 56 1/s, 14 1/s and 20 l/min, respectively.
32
Table 4.5: Efficiency and operating hours of pumps Types of Pump Efficiency Monthly operating hours per day (Avg.) January February March April
DTW 0.70 8 10 14 14 STW 0.70 8 10 14 14
Hand pump 0.60 8 8 8 8
The monthly abstraction rates for each Upazila is calculated as follows
Qabs= Ndtw. Cdtw. Edtw. Hdtw. + Nstw.Cstw.Estw.Hstw ...... (4.1)
Qabs = monthly abstraction for a Upazila
Ndtw = number of deep tube wells within the Upazila
Cdtw. = pump capacity of deep tube well
Edtw = pump efficiency of deep tube well
Hdtw = running hours per month
Nstw = number of shallow tube wells within the Upazila
Cstw = pump capacity of shallow tube well
Estw = pump efficiency of shallow tube well
Hstw = running hours per month
Using Equation (4.1), abstraction by different modes of tube wells is estimated.
4.3 Data Analysis The processed groundwater level, river water level, and the river discharges data have been analyzed both graphically and statically to compare the pre and post project conditions of groundwater level, river water levels, and the river discharges and to evaluate the impact of the TBP in the project groundwater conditions and the pre and post project magnitude of changes in river water level and discharges. The groundwater data have been analyzed inside of project area, outside of project area and close to river side
33 area. Data have been analyzed on weekly, monthly and yearly average of groundwater level. The data of groundwater level and rainfall with time, groundwater level and river water level with time and the abstraction of groundwater and groundwater level with time have been analyzed both graphically and statically to find out any trend. The monthly groundwater abstractions by shallow tube well, deep tube well and the hand tube well for the project area have been calculated from the available data. The changes in irrigated agriculture acreage through groundwater and surface water with time during the different cropping seasons have been calculated by analyzing the data on the pre and post project irrigation of the project area.
34 CHAPTER 5
RESULTS AND DISCUSSIONS
The present study evaluates the changes in groundwater conditions and the overall impact on irrigation coverage in the study area due to implementation of the Teesta Barrage Irrigation Project. The analysis covers the pre and post project groundwater conditions, river water conditions, water withdrawal and its impacts on groundwater level, changes in irrigation coverage, and the changes in agricultural production. One of the major objectives of the present study is to evaluate the post project groundwater condition in the project area to see the prospect of further groundwater use for agricultural purpose.
5.1 Variation of Groundwater Level To estimate the availability of groundwater for agricultural and other uses, it is very important to see the variation of the groundwater level with time. So the weekly and yearly groundwater level variation, changes of groundwater level within and outside the project area, impact of river water level on the groundwater level, groundwater withdrawal and its impacts on groundwater level, and the regional variation of groundwater level over the project area have been analyzed.
5.1.1 Weekly variation of groundwater level inside TBP For better understanding of the changes in groundwater level and to make a comparison between pre and post project groundwater conditions an analysis was done with the weekly data within the project area. Similar analysis was done for outside the project area to evaluate the impact of the project on the groundwater system in the area. Figures 5.1 and 5.2 show the pre and post project variation of groundwater level at two observation wells within the project area and it is observed that groundwater level has increased at both locations during the project period and the magnitudes of increase in two locations are very close. The scenario is completely different outside the project area. Figure 5.3 shows that in Dinajpur (DIN-029) the groundwater level has decreased during the post project time. This indicates that the Teesta Barrage Irrigation Project has impact on the groundwater recharge in the project area. This also indicates that a significant amount of water got lost from the surface water irrigation system during the irrigation period. In the project area, irrigation is employed both for Kharif 1 and Rabi crops although the project was conceived for the Kharif 11 supplementary irrigation.
35 But with the need of the area, irrigation water is also supplied for the Rabi season. The result indicates that more recharge is caused during the dry season irrigation than the Kharif 1 season irrigation. The reason is the dryness of the soil during the Rabi Season.
Pre-Project, Year-1990 Post-Project, Year-2002
51 50.5 50 49.5 49 48.5 48 47.5
GroundwatermPWD Level, 47 1 6 11 16 21 26 31 36 41 46 51
Week
Figure 5.1: Weekly variation of groundwater level at well NIL-05 in Dimla Upazila
Pre-Project, Year-1990 Post-Project, Year-2002
34 33 32 31 30 29 28 27 GroundwatermPWD Level, 1 6 11 16 21 26 31 36 41 46 51
Week
Figure 5.2: Weekly variation of groundwater level at well RA-07 in Rangpur Sadar Upazila
36 Pre-Project, Year-1990 Post-Project, Year-2002
48 47 46 45 44 43 42
Groundwater Level, mPWD Level, Groundwater 41 1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101
Week
Figure 5.3: Weekly variation of groundwater level outside of project at well DIN-29 in Domer Upazila
5.1.2 Yearly variation of groundwater level inside TBP To estimate the availability of groundwater for agricultural and other uses, it is very important to see the variation of groundwater level over the years. To evaluate the changes in groundwater over the years in the study area, the maximum and the minimum water level has been graphically presented over the years from 1990 to 2006 for different observation wells located in the study area. Figures 5.4 to 5.11 show the variations of the groundwater level over the years from 1990 to 2006. From the figures increasing trend of groundwater level has been observed as before after implementation of the project except in few cases. In well NIL-20, the minimum water level has been found with slightly decreasing trend. The figures also support that the maximum and the minimum water level follow the similar trend.
37 Maximum Minimum
51.5 51 50.5 50 49.5 49 48.5 48 47.5 47 46.5 Groundwater Level, mPWD Level, Groundwater
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
Figure 5.4: Variation of groundwater level with time at well NIL-05
Maximum Minimum
49 48 47 46 45 44 43 42 Groundwater Level, mPWD Level, Groundwater
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
Figure 5.5: Variation of groundwater level with time at well NIL-20
38 Maximum Minimum
45 44 43 42 41 40 39 38 GroundwatermPWD Level,
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.6: Variation of groundwater level with time at well NIL-23
Maximum Minimum
39 38 37 36 35 34 33 32 31 30 GroundwatermPWD Level,
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.7: Variation of groundwater level with time at well NIL-27
39 Maximum Minimum
49 48 47 46 45 44 43 42 41 GroundwatermPWD Level,
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.8: Variation of groundwater level with time at well NIL-25
Maximum Minimum
37 36 35 34 33 32 31 30 29 GroundwatermPWD Level,
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.9: Variation of groundwater level with time at well RA-03
40 Maximum Minimum
35 34 33 32 31 30 29 28 27 26 GroundwatermPWD Level,
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.10: Variation of groundwater level with time at well RA-07
Maximum Minimum
43 42 41 40 39 38 37 36 35 GroundwatermPWD Level,
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.11: Variation of groundwater level with time at well DIN-13
5.1.3 Regional variation of groundwater level With the available groundwater data in 14 observation wells for the years 2000 and 2006, the groundwater surface maps have been drawn for yearly maximum and minimum water level. The yearly groundwater surface contour maps for the maximum and the minimum water level are shown in Figures 5.12 and 5.13. In the upstream region, in general the water flows from north to south. However in the downstream region, the regional contour maps of maximum and minimum water table shows that the general direction of flow of groundwater is from north west to south east which is similar to the normal trend of
41 groundwater flow in Bangladesh both in dry and wet seasons. Figure 5.12 shows that the maximum groundwater level is increasing with time and the water level of 2006 is significantly higher than that of the year 1992 almost all over the region with exception in some location in the south west region of the area. The similar regional trend is also observed for the minimum groundwater level (Figure 5.13). Therefore it can be further concluded that the project area is gaining the groundwater level during the post project time and this gains sustains all over the year.
42 Figure 5.12: Maximum groundwater level contour map for 1992 and 2006
43
Figure 5.13: Minimum groundwater level contour map for 1992 and 2006
44 5.2. Groundwater Withdrawal The groundwater in the study area is withdrawn for irrigation by different means of withdrawal. The groundwater withdrawal rate is increasing significantly all over the project area especially for dry period irrigation. To see the Upazilawise groundwater withdrawal pattern, the groundwater withdrawal data from the year 1990 to 2006 have been used. Figures 5.14 to 5.16 show the variations of average groundwater withdrawal over per sq km of the project area over the years for 8 Upazilas in the in the Teesta Barrage Project area. These figures show an increasing trend of groundwater withdrawal in all the upazilas. In a span of 16 years the withdrawal rate has increased about 5 times. In Gangachara and Rangpur sadar upazilas rate of withdrawal has increased most and in Jaldhaka Upazila, the rate of withdrawal has increased least. Figure 5.14 shows the total groundwater withdrawal for irrigation and domestic uses. Figures 5.15 and 5.16 show the withdrawal separately for irrigation and domestic uses, respectively. Comparison between Figure 5.15 and Figure 5.16 shows that the groundwater withdrawal for irrigation is significantly higher than that of domestic purposes and the rate of increase for irrigation is also higher than the rate of increase of withdrawal for domestic purposes.
1.8
2 Dimla 1.6
/km Jaldhaka
3 1.4 1.2 Kishoregonj 1 Saidpur 0.8 Nilphamari Sadar 0.6 Rangpur 0.4 Gangachara 0.2 Chirirbandor 0 Total Total Withdrawal, Mm
1990 1992 1994 1996 1998 2000 2002 2004
Year
Figure 5.14: Withdrawal of groundwater per sq-km
45 Dimla 2 1.6
/km 1.4 Jaldhaka 3 1.2 Kishoregonj 1 0.8 Saidpur 0.6 Nilphamari 0.4 Sadar 0.2 Rangpur 0 Gangachara IrrigationWithdrawal,Mm
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Chirirbandor
Year
Figure5.15: Irrigation withdrawal of groundwater per sq-k
Dimla
2 0.16 0.14 Jaldhaka /km 3 0.12 Kishoregonj 0.1 0.08 Saidpur 0.06 Nilphamari 0.04 Sadar 0.02 Rangpur 0 Gangachara DomesticWithdrawal,Mm 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 Chirirbandor
Year
Figure 5.16: Domestic withdrawal of groundwater per sq-km
5.2.1 Groundwater withdrawal at different months by different means Figures 5.17 to 5.19 show the monthly total average withdrawal of groundwater by various methods of withdrawal and Figure 5.20 show the monthly total average withdrawal of groundwater by various methods. Groundwater is being withdrawal mostly by shallow tube well and low by hand pump. Groundwater withdrawal rate is high in March and low in January. After project implementation groundwater withdrawal rate is increasing day by day. Figure 5.17 shows the withdrawal by shallow tube wells and Figure 5.18 shows the withdrawal by deep tube wells and Figure 5.19 shows the withdrawal by hand pump. The rate of increase of average groundwater withdrawal by shallow tube wells is very high and the maximum withdrawal occurs in the month of March and April (Figure 5.17). The deep tube well withdrawal is increased up to the year
46 1996 and the constantly the withdrawal rate is decreased and the maximum withdrawal again occurs during the month of March and April. The withdrawal by hand tube wells is significantly less than that of shallow tube wells, however the rate of withdrawal has increased constantly( Figure 5.19). Total groundwater withdrawal increases significantly over the years by shallow tube wells which has significant impact on the total withdrawal (Figure 5.20).
January February March April
600
3 500
400
300
200
Withdrawal, Withdrawal, Mm 100
0 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
Figure 5.17: Monthly withdrawal of groundwater by shallow tube well
January February March April
25
3 20
15
10
Withdrawal, Withdrawal, Mm 5
0 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
Figure 5.18: Monthly withdrawal of groundwater by deep tube well
47 January February March April
20 18
3 16 14 12 10 8 6
Withdrawal, Withdrawal, Mm 4 2 0 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
Figure 5.19: Monthly withdrawal of groundwater by hand pump
Shallow Tube Well Deep Tube Well Hand Pump Total Withdrawal
1800 1600 3 1400 1200 1000 800 600 400 Withdrawal, Withdrawal, Mm 200 0 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
Figure 5.20: Total Withdrawal of Groundwater by shallow tube well, deep tube well and hand pump
5.3 River Water Level To estimate the availability of surface water for agricultural and other uses, it is very important to see the variation of the surface water level with time. To evaluate the changes in surface water level of the Teesta River the maximum and the minimum water level has been graphically presented with time. The data from the year 1990 to 2005 have been plotted. Figures 5.21 to 5.24 show the variations of the surface water level with time. From these figures it is observed that maximum discharge occurs in August (Kharif -11 season) and the minimum discharge occurs in February (Rabi season).
48 The water levels of the Teesta River upstream and downstream of the Teesta Barrage influence the groundwater level of the project area. The changes in water level during the study period at upstream and downstream of the Barrage was investigated before evaluating the impacts of Teesta river water level on the groundwater level of the area. Figures 5.21 and 5.22 are the water level hydrographs of the downstream water level at BWDB gages SW_291.5R and SW_291.5L at Dalia and Doani, respectively and SW_293 further downstream at Kaunia. Figure 5.24 is the water level hydrograph of the upstream river water at BWDB gages SW_291L at Kharibari. From these figures decreasing trend of water level has been observed. However, from Figure 5.24 (upstream), it is observed that decreasing trend of minimum water level is minimal since the project implementation. The decreasing trend at the downstream is relatively higher for the minimum water level.
Maximum Minimum
54 53 52 51 50 49 48 47
River Water Level, mPWD Water River 46 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
Figure 5.21: Maximum and minimum river water level at Dalia (SW_291.5R)
Maximum Minimum
54 53 52 51 50 49 48 47
River Water Level, mPWD Water River 46 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
Figure 5.22: Maximum and minimum river water level at Doani (SW_291.5L)
49 Maximum Minimum
41 40.5 40 39.5 39 38.5 38 37.5 37
River Water Level, mPWD Water River 36.5 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
Figure 5.23: Maximum and minimum river water level at Kaunia (SW_293)
Maximum Minimum
57
56
55
54
53
52 River Water Level, mPWD Level, Water River 1992 1993 1994 1995 1996 1997
Year
Figure 5.24: Maximum and minimum river water level at Kharibari (SW_291L)
5.4 Relation between Groundwater Level and River Water Level The aquifer of the project area is hydraulically connected with the water level of the Teesta River. As a result the groundwater level of the project area is influenced by the river water level at the vicinity of the project. Figures 5.25 indicate the relationship between the groundwater level of Dimla Upazila (Year-1992) and the Teesta river water level (Year-1992) has been evaluated graphically as a pre project. Figures 5.26 indicate the relationship between the groundwater level of Dimla Upazila (Year-2000) and the Teesta river water level (Year-2000) has been evaluated graphically as a post project. It is observed from these figures that when river water level is increased, groundwater level is also increased. However, it is also observed that there is lag time between the occurrence maximum river water level and the maximum groundwater level. The length of the lag is
50 about two months during pre project time which means the peak of the groundwater level is attained after two months of the peak of the river water level. However, the length of the lag is about a month during post project time which means the peak of the groundwater level is attained after one months of the peak of the river water level. This shows that the recharge of groundwater is faster during the post project period and this may be due to increase recharge from the supplied irrigation water.
GWL RWL
52 51 50 49
mPWD 48 47
Monthly Water Level, Level, Monthly Water 46 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Figure 5.25: Groundwater level and water level (pre-project)
GWL RWL
52.5 52 51.5 51 50.5 50 49.5 49 48.5 48 47.5 Monthly Water Level, mPWD Level, Monthly Water Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Figure 5.26: Groundwater level and water level (post-project)
51 5.5 Relation between Groundwater Level and Rainfall To estimate the availability of groundwater for agricultural and other uses, it is very important to see the variation of groundwater level and rainfall with time. To evaluate the changes of groundwater level and rainfall of the Teesta Barrage Project area groundwater level rainfall data has been graphically presented with time. The data from the year 2000 and 2005 have been plotted. Figures 5.28 to 5.29 show the variations of groundwater level and rainfall with time.
Figure 5.27: Groundwater level at well NIL-05 and rainfall of Dimla in the year 2000
Figure 5.28: Groundwater level at well NIL-05 and rainfall of Dimla in the year 2005
52 5.6 Irrigation Coverage in the Project Area Irrigation is the main factor for increasing agricultural crop production especially the HYV paddy. Teesta Barrage project was conceived and implemented to give supplementary irrigation to T. Aman paddy. There was no plan to give irrigation to Boro paddy. As Boro paddy needs much water and the supply of water in the canal goes down to the minimum level during January and February, Boro was not initially irrigated by canal water. Some area of Boro was cultivated, irrigating by STW, in farmer’s own arrangement. But after February the level of water in the canal gradually goes up as a part of Aus Paddy area was initially irrigated by canal water from March. As a result of continuous supply of irrigation water by this time the ground water level has come up, the structure of the soil has changed, water holding capacity has increased. The fields near the main canal always get seepage water. So, the farmers are cultivating Boro HYV at their own initiative. They prepare the seedbed and transplant using irrigation through STW. From March the irrigation water is supplied by BWDB. As the irrigation is started by BWDB from March they show this paddy area as Aus, which should actually be Boro. In this report it is shown as Boro HYV and the service charge is imposed for T. Aman at a rate Taka 180.00 and for Boro at Taka 300.00 per season per hectare. This charge is collected by the beneficiaries of Water Management Groups and deposited with the bank in a joint account operated by Executive Engineer and the President of the Association. The irrigation coverage by groundwater and surface water during both the seasons are increasing with time after implementation of the project. The irrigated area during Kharif I and Kharif II are shown in Figures 5.30 and 5.32, respectively for surface water and groundwater
53
Figure 5.29: Irrigable area of Karif-11 and Karif-1
Figure 5.30: Irrigation coverage by surface water
Figure 5.29 refers to the irrigable area of Kharif-11 and Kharif-1. Figure 5.30 refers to the irrigation coverage by surface water. From Figure 5.30, it is observed that irrigation coverage by surface water in the project area (during Kharif-11 and Kharif-1) has been increased day by day. But during Rabi or dry season canal water was not available then farmer abstraction groundwater by shallow tube well and deep tube well on their own arrangement. Analysis was further done to see the Upazila wise irrigation coverage. Figure 5.31 shows the gross, irrigable area and irrigable area in the project in all eight upazilas either partially or fully covered by the project area. Figure shows that
54 Kishoregonj Upazila has been fully covered by the project and has the maximum irrigable area within the project and the Upazila has minimum irrigable land covered by the project. In addition to Kishoregonj, the irrigable area of Saidpur upazila is brought under irrigation completely.
Gross area Irrigable area Irrigable area w ithin the project
40000 35000 30000 25000
Area,ha 20000 15000 10000 5000 0
Dimla Saidpur Jaldhaka Rangpur Nilphamary Kishoregonj GangacharaChirirbandar
Upazila Figure 5.31: Gross and irrigable area within the project .
Year-2005 Year-2006 Year-2008 18000 16000 14000 12000 10000 8000 6000
Irrigated Area, ha Area, Irrigated 4000 2000 0
Dimla Jaldhaka Saidpur Rangpur Nilphamary Kishoregonj Gangachara Chirirbandar
Upazila Figure 5.32: Irrigation coverage by groundwater
Figure 5.32 shows that irrigation coverage by groundwater in the project area has been increased day by day. The localized and the regional variation of groundwater level since the implementation of the project was discussed at the beginning of this chapter.
55 5.7 Variation of Groundwater Level with Groundwater Withdrawal To see the potential of future groundwater use for irrigation it is necessary to see the change in groundwater level due to withdrawal of groundwater. In the current study this changes has been evaluated both inside and outside the project area. The comparison between the changes within and outside the project area will show the impact of the project on such changes.
5.7.1 Groundwater level changes inside the project area To evaluate the changes in groundwater in response to groundwater withdrawal in the study area, the maximum, minimum water level and the groundwater withdrawal have been graphically presented for different observation wells in the study area. The data from the year 1990 to 2006 have been used for this purpose. Figures 5.33 to 5.40 show the variations of the groundwater level and withdrawal of groundwater. From these figures increasing trend has been observed from during the project implementation except in few cases. Figures also support that the changes of maximum, minimum water level and the withdrawal of groundwater follow the similar trend in all the Upazila of the project area. However, in all the Upazila the increase in the rate of withdrawal is faster than the rate of changes in either in maximum and minimum water levels. Further it is observed that the deflation rate of groundwater level ie the difference between the maximum and the minimum groundwater level is constant all through the period and all over the area. In every case the rate of increase in maximum water level is almost same as the minimum groundwater level. So with the increase of irrigation coverage by surface water, the groundwater storage is increasing.
56 Maximum GWL Minimum GWL Withdrawal
51.5 80
51 70 3 50.5 60 50 49.5 50 49 40
mPWD 48.5 30 48 47.5 20
10 Withdrawal, Mm Groundwater Level, Groundwater 47 46.5 0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.33: Variation of groundwater level and groundwater withdrawal at well NIL-05 in Dimla Upazila
Maximum GWL Minimum GWL Withdrawal
49 250
48 3 200 47 46 150 45
mPWD 100 44 50
43 Withdrawal, Mm Groundwater Level, Groundwater 42 0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.34: Variation of groundwater level and groundwater withdrawal at well NIL-20 in Jaldhaka Upazila
57 Maximum GWL Minimum GWL Withdrawal
45 300 3 44 250 43 200 42 150 41 mPWD 40 100 39 50 Withdrawal, Withdrawal, Mm
Groundwater Level, Groundwater 38 0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.35: Variation of groundwater level and groundwater withdrawal at well NIL-23 in Kishoregonj Upazila
Maximum GWL Minimum GWL Withdrawal
49 180 48 160 3 47 140 46 120 100 45 80 mPWD 44 60 43 40 Withdrawal, Withdrawal, Mm 42 20 Groundwater Level, Groundwater 41 0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.36: Variation of groundwater level and groundwater withdrawal at well NIL-25 in Nilphamari Sadar Upazila
58 Maximum GWL Minimum GWL Withdrawal
39 160 38 140 3 37 120 36 100 35 34 80
mPWD 33 60 32 40
31 20 Withdrawal, Mm
Groundwater Level, Groundwater 30 0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.37: Variation of groundwater level and groundwater withdrawal at well NIL-27 in Saidpur Upazila
Maximum GWL Minimum GWL Withdrawal
35 250
34 3 33 200 32 31 150 30 100 mPWD 29 28 50 27 Withdrawal, Withdrawal, Mm
Groundwater Level, Groundwater 26 0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.38: Variation of groundwater level and groundwater withdrawal at well RA-07 in Rangpur Sadar Upazila
59 Maximum GWL Minimum GWL Withdrawal
37 250 3 36 35 200 34 150 33 100
mPWD 32 31 50
30 Withdrawal, Mm
Groundwater Level, Groundwater 29 0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.39: Variation of groundwater level and groundwater withdrawal at well RA-03 in Gangachara Upazila
Maximum GWL Minimum GWL Withdrawal
43 80
42 70 3 41 60 40 50 39 40
mPWD 38 30 37 20
36 10 Withdrawal, Mm Groundwater Level, Groundwater 35 0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Figure 5.40: Variation of groundwater level and groundwater withdrawal at well DIN-13 in Chirirbandar Upazila
5.7.2 Groundwater level changes outside the project area To see the effect of groundwater withdrawal on the groundwater level an analysis was done outside the project area. Figure 5.41 shows that groundwater level of the outside of the project area has been decreasing day by day with the groundwater withdrawal. The increase rate of withdrawal of groundwater is similar to that of within the project area. From sections 5.8 and 5.9 it can be inferred that the seepage from surface water irrigation significant impact on increasing the groundwater table in the project area.
60 Maximum GWL Minimum GWL Withdrawal
30 25 3 25 20 20 15 15 10
mPWD 10 Withdrawal, Withdrawal, Mm 5 5 Groundwater Level, Groundwater 0 0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
Figure 5.41: Variation of groundwater level and groundwater withdrawal at well DIN-29 in Domer Upazila
5.8 Prediction of Groundwater Level Using Linear Regression Model To evaluate the impact of rainfall, river water level and groundwater withdrawal on the changes in groundwater storage statistical analysis was done with regression model (Snedecor and Cochran, 1978; Wilks, 2006) as follows:
Y = C0 + C1X1 + C2X2 + C3X3 (5.1)
Where, Y = Groundwater level=Dependent variable and C0, C1, C2 and C3 are the constants and X1, X2 and X3 are river water level, rainfall and groundwater withdrawal, respectively. Using the above equation and the historical pre and post project groundwater, rainfall and groundwater withdrawal data two sets of equations (one for pre and the other for post project) would be developed to estimate pre and post project groundwater storage changes. Taking the average value of various stations of pre and post project period and using the multiple linear regression of MS Excel the Equation (5.1) resulted into the following forms:
Y = 52.79 + 0.63X1 + 0.0018X2 - 0.16X3 (5.2) for pre project period, and
Y = 53.82 + 0.74X1 + 0.0019X2 - 0.0012X3 (5.3)
61 for post project period.
The values of the coefficient determination, R2 for pre and post project are 0.53 and 0.70, respectively. This indicates that the combined impact rainfall, river water level and the withdrawal on the groundwater storage is stronger during the post project period than the pre project condition. An evaluation was done to see the variation of the combined impact rainfall, river water level and the withdrawal on the groundwater storage at different Upazilas. The result is presented in Figure 5.42. It is observed from the figure that in all the Upazilas the post project influence is stronger than the pre project condition. In Dimla Upazila the relation is stronger which is followed by Nilphamary Sadar. In Saidpur Upazila the relation is observed to be the weakest. The regression Equation (5.3) may well be used to groundwater level changes with the changes to the independent variables and thus estimate the changes in groundwater storage in the area.
Pre-Project Post-Project
1 2 0.8 0.6 0.4 0.2 Value of R 0
Dimla Saidpur Jaldhaka Kishoregonj Gangachara Chirirbandor Rangpur sadar Nilphamary sadar Upazila
Figure 5.42: Upazilawise value of coefficient of determination, R 2
The impact of canal and river distances from the observation wells on the groundwater level in the project area has been evaluated. It is observed, when observation wells are nearest from the main canal and river then groundwater level increase and when observation wells are far or more distance from the main canal and river then groundwater level decrease (Figure 5.43). There is no major impact of rainfall, so it is supposed to be similar amount of rainfall pre-project and post-project.
62 Canal River Year-2000 Year-2006
60 60 50 40 40 20 30 0 20 -20 10 -40
0 -60 cm Increased, Well distance from Well distance Groundwater Level Level Groundwater Canal and River, km Canal
Dimla Saidpur Domer Jaldhaka Rangpur NilphamaryKishoregonj GangacharaChirirbandar Upazila
Figure 5.43: Impact on groundwater level from various distances to canal and river
5.9 Need and Potential for Groundwater Use 5.9.1 Availability of surface water To estimate the availability of surface water for agricultural and other uses, it is very important to see the variation of the river water level and discharge with time. To evaluate the changes in surface water level of the Teesta River the maximum and the minimum water level has been described in earlier section. To see the variation in discharges, data from the year 1990, 2000 and 2005 of the Teesta River have been plotted. Figure 5.44 shows the variations of discharges with time. From the figure, it is observed that the maximum discharge occurs in August (Kharif -II season) and the minimum discharge occurs in February (Rabi season). The design irrigation water requirement for both phase- 1 and phase-11 of the Project is 238 m3/sec and 293 m3/sec for Kharif-11 and Rabi (Boro) seasons, respectively (TBP, 2005). When the Phase II is completed, the total requirement would be double, 476 m3/sec during the Kharif II and 586 m3/sec during the Rabi seasons.
63
Figure 5.44: Monthly discharges of Teesta during Kharif-I, Kharif-II and Rabi season
Figure 5.45: Monthly discharges of Teesta during Kharif-I
64
Figure 5.46: Monthly discharges of Teesta during Rabi season
From analysis of discharge data of the Teesta River at the project site from 1990, 2000 and 2005 it is observed that the maximum discharge has reached to 3363 m3/sec and the minimum discharge has never fall below 238 m3/sec during Kharif-11. So the surface water is available for Kharif-11 and for later part of the Kharif 1 seasons. But surface water flow is not enough in comparison to the present irrigation requirement of the completed Phase I of the project during the Rabi (Boro) season and the flow is decreasing with time and will decrease significantly due to possible cross boarder upstream withdrawal. Figure 5.44 shows that the monsoon season flow has decrease about 40 % from in 15 years from the year 1900 to 2005. The rate of decrease of the dry season flow is almost similar. Figure 5.45 shows that during Kharif I season, the discharge of the Teesta River is also decreasing although the rate of decrease is higher during later part of the season. Figure 5.46 shows that during the Rabi (Boro) season the river discharge is decreasing significantly and the rate of decrease is higher in the later part of the season. From the year 1990 to 2005 the river flow has decreased about 15 % and the rate of decrease has increased with time which about 48% during the end of the season. This is highly alarming in terms of the quantity of flow which is less than 100 m3/sec and the rate of decrease as well considering the irrigation requirement and in stream requirement.
65 5.9.2 Crop production with current conditions Present level of crop yield is calculated on the basis of collection of data from the Upazila offices, BWDB officials and farmer’s interview in the project area. Figure 5.47 refers to Upazilawise crop yield and production of pre-project and post-project and Figure 5.48 refers to Upazilas wise percent crop yield and production.
Year-1992 Year-2005 Year-2008
6 5 4 3 2 1 Yield M.T /haM.T Yield 0
Dimla Jaldhaka Saidpur Rangpur Nilphamary Kishoregonj Gangachara Chirirbandar
Upazila Figure 5.47: Upazilawise crop yield and production of pre-project and post-project
Year-2005 Year-2008
120% 100% 80% 60% 40% 20% 0% Crop Yield Increase, % Increase, Crop Yield
Dimla Jaldhaka Saidpur Rangpur Nilphamary Kishoregonj Gangachara Chirirbandar
Upazila Figure 5.48: Upazilawise % increase crop yield and production
It is observed from the (Figure 5.47) that Upazila wise crop yield and production increase per hectare after project implementation. The influence of drought, insect, paste and diseases also reflected upon yield rate of crops. The yield of crops has been increased after project implementation and with time the rate is continued to increase (Figure 5.48).
66 The Upazila Dimla, Khishoreganj Sadar and Chinirbander experienced the highest increase in crop production which almost double. The Upazila Jaldhaka and Gangachara experienced the least increase which is 60 %. However, the 60% increase of crop production can be also considered significant.
5.9.3 Potential of groundwater use in conjunction with surface water The groundwater conditions so far discussed shows that in the project area the groundwater level is increasing with time due to the recharge from the surface water irrigation from the Teesta River since the implementation of the project. With time there is a significant increase in the withdrawal of groundwater mostly with the private initiative, but the groundwater level does not show any decreasing trend to its upward trend due to recharge mostly by the surface water irrigation. But the river discharge analysis presented in Figures 5.44, 5.45 and 5.46 gives alarming messages as the flow is decreasing with time in all the cropping seasons. If the flow of the river could not be maintained, it will have a negative impact to increase the crop production through irrigation. So the flow of the Teesta River is vital source not only for irrigation but for recharging the groundwater which is also a source of irrigation water especially during dry period irrigation.
The availability of surface water from the Teesta River in the project area is insufficient during the boro season and partly during the early part of Kharif 1 season (Figure 5.44). So, the project is running with the shortage of designed requirement of irrigation water. Even with this shortage the project has increased significant crop production all the Upazilas within the project area as shown in Figures 5.47 and 5.48. Therefore, as the groundwater is available within the project area, the use of this groundwater resource during Boro and Kharif 1 seasons bring potential benefit in terms of bring more cultivable area under irrigation and eventually increasing the crop production in TBP.
67 CHAPTER 6
CONCLUSIONS AND RECOMMENDATIONS
6.1 Conclusions
Based on the study the following conclusions can be made:
1. The Teesta Barrage Project has positive impact on recharging the groundwater in the project area. Since the implementation of the project the groundwater level is increasing despite the significant increase in groundwater withdrawal by different mode of withdrawals.
2. The aquifer is recharged with the surface water supplied to the irrigation canals from the project for irrigating crops during the Kharif 11 season since the inception of the project. This also supports that a significant portion of water supplied from the Project got lost through seepage during conveyance and deep percolation and contributes to groundwater. This is further observed that the aquifer is also recharged from the adjacent rivers directly as long as the water level of the river is higher than the aquifer water level.
3. Both the yield and the rate of crop production have increased significantly since the implementation of the Teesta Barrage Project. In some areas the crop production has increased to hundred percent and the minimum increase is 60 percent.
4. The statistical model developed to see the influence of rainfall, river water and groundwater withdrawal on aquifer water level shows that the river water level has more influence than others on the groundwater level and the combined impact is stronger during the post project than the pre project condition. The formulated regression model may be useful to predict the increase in groundwater level thus estimating the increase in groundwater storage.
68 5. The availability of surface water in the Teesta Barrage Project is sufficient to meet the design water requirement for Kharif 11 and major part of the Kharif 1. But the availability of surface water from the project during Rabi season is not enough to meet the design irrigation requirement.
6. The Teesta River discharge is decreasing significantly with time all through the year. From 1990 to 2005 the discharge has decreased to 40% both in Kharif II and Rabi seasons; however, this figure is less during the Kharif I season. This decreasing rate is very alarming considering (i) availability of surface water for irrigation, (ii) recharging the aquifer and future availability of groundwater and (iii) dry season in stream water requirement.
7. The decrease in flow of Teesta River has two fold negative impacts such as (i) non-availability of water for surface irrigation and (ii) non-availability of surface water for irrigation means no recharge to the groundwater and this would affect the groundwater irrigation most importantly during the dry season.
6.2 Recommendations
Based on the study the following recommendations are made:
1. The decreasing rate of Teesta River discharge is very alarming considering availability of surface water for irrigation, recharging the aquifer and future availability of groundwater and dry season in stream water requirement. A thorough study is required in this respect.
2. The groundwater has bright prospect to be used in conjunction with the surface water supplied from the Teesta Barrage Project provided the surface water is available at the Teesta River to supply design water requirement for supplementary irrigation during Kharif II which helps aquifer to be recharged that can be used for irrigation of the Rabi (Boro) crops. A detail study in this connection is required.
3. A thorough study on the later recharge from the adjacent aquifer is required.
69 REFERENCES
ADB (1992), “Review of Options for the Development of Ground and Surface Water Irrigation Project”, Final Report, Asian Development Bank, Dhaka
Alam, M. and Kabir, W. (2004), “Irrigated Agriculture in Bangladesh and possible impact due to Inter-Basin Water Transfer as planned by India”, ASAE/CSAE Meeting, Paper No.042290, ASAE, St. Joseph, Mich.USA
BWDB (2005a), “Impact Evaluation of TBP Phase-I”, Final Report, Bangladesh Water Development Board, Dhaka, Bangladesh
BWDB (2005b), “Development of Project Proposal for TBP Phase-11”, Bangladesh Water Development Board, Dhaka, Bangladesh
BWDB (2006), “Development of Project Proposal for TBP phase-11”, Bangladesh Water Development Board, Dhaka, Bangladesh
Higano, Y. and Islam, M. F. (undated), “Rural Poverty Alleviation through Large-scale Irrigation Planning: Problem and Prospects of the Dalia Barrage Project”, Bangladesh Institute of Agricultural and Forest Engineering, University of Tsukuba, Japan
Hossain, A. F. M. A.(2010), “Improved Irrigation Management for Increased Food Production using Mathematical Modeling”, Knowledge Globalization Conference, Proceedings Journal, Vol. 2, No. l, Boston, Massachusetts, USA
Hoque, M. M and Islam, A.K.M.S (2000),”Conjunctive use of Surface Water & Groundwater for irrigation in Buri-Teesta irrigation project”, Final Report, IFCDR, BUET, Dhaka
IMED (2008), “Evaluation Study on Teesta Barrage (1st Phase) Project”, Ministry of Planning, Government of the People’sRepublic of Bangladesh
70 Islam, M. F. and Akmam, W. (2007), “Changes in Socio-economic and Environmental Situations in the Dalia Irrigation Project Area During 2000-2007: Policy Recommendations”, Journal of Bangladesh Studies, Vol. 9(1)
IWM (2003), “Command Area Development of Teesta Barrage Project: Phase 1”, Main Report, Vol. 1, Institute of Water Modeling, Dhaka
IWM (2004), “Command Area Development of Teesta Barrage Project: Phase-I”, June 2004, Final Report, Bangladesh Water Development Board, Dhaka
Khan (1988),“Determination of Transplanting Date and Supplementary Irrigation Requirement for HYV Monsoon Rice Using Rainfall”, Crop and Soil data, Bangladesh Journal of Water Resource Research, Vol. 1, No. 1
MPO (1985), “Improvement of Irrigation Water Management”, Technical Report No. 3. Ministry of Water Resources, Government of the People’s Republic of Bangladesh
MPO (1987), “The Groundwater Resource and Its Availability for Development”, Technical Report No. 5, Ministry of Water Resources, Government of the People’s Republic of Bangladesh
MPO (1991), “The Groundwater Resource and Its Availability for Development”, Technical Report No. 6. Ministry of Water Resources, Government of the People’s Republic of Bangladesh
MWR (1999), “National Water Policy”, Ministry of Water Resources, Government of the People’s Republic of Bangladesh
MWR (2001),” National Water Management Plan”,Vol.1, Ministry of Water Resources, Government of the People’s Republic of Bangladesh
Rahman, M. M. (2008), “Impacts of Climate Change on Command Area Development of Teesta Barrage Project”, M.Sc. thesis, Institute of Water and Flood Management. Bangladesh University of Engineering and Technology, Dhaka
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Saleh, A.F.M., Islam, M. Z. and Kunda, R.N. (1991),“Study on Seepage Loss and Cost Effective L for Teesta Barrage Project”, Final Report, Institute of Flood Control and Drainage Research, Bangladesh University of Engineering and Technology, Dhaka
Snedecor, G.W and Cochran , W.G (1978),” Statistical Methods”, Sixth Edition, The Iowa University Press, Ames, Iowa
SWMC (1996 ), “Further Study on the Hydro logical Processes in the Jamuneswari Basin”, Surface Water Modeling Centre, Dhaka
SWMC (2000), “Surface Water Groundwater Interaction Model Study”, Technical Report No. 6, National Water Management Plan, Water Resources Planning Organization, Dhaka
SWMC (2002), “Development of Decision Support Services Using Mathematical Modeling Technique” Surface Water Modeling Centre, Dhaka
Wahid, S. M. (2003), “International Watershed Management: Studies and Experiences”, MSc. Thesis (Ref. No. WM-02-13), Asian Institute of Technology, Bangkok, Thailand.
Wilks, D. S (2006), “Statistical Methods in the Atmospheric Sciences”, 2nd Edition, Elsevier, New York
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