GOVERNMENT OF ETHIOPIA MINISTRY OF WATER RESOURCES HYDROGEOLOGICAL DATA/ ANALYSIS ANNEX - 3 AMIBARA DRAINAGE PROJECT PHASE-II PREPARATION OF DETAILED DESIGNS,, TENDER^BqCUMENTS, PROJECT PREPARATION REPORT AND ENVIRONMENTAL IMPACT ASSESSMENT REPORT ci i «-cr?l WATER AND POWER CONSULTANCY SERVICES (INDIA) LTD (International Consultants in Water Resources) KAILASH', 26, KASTURBA GANDHI MARG., NEW DELHI - 110 001, INDIA v fixSection HYDROGEOLOGICAL DATA/ANALYSIS TABLE OF CONTENTS Description TABLE OF CONTENTS LIST OF TABLES Page No 1 iii LIST OF FIGURES LIST OF APPENDICES 1.0 INTRODUCTION 1.1 Location 1.2 Cli mate IV iv I 1 1 1.3 Soils and Geomorphology 1.4 Geology and Hydrogeology 1.5 Irrigation Practices 1.6 Drainage n 3 4 4 2.0 GROUNDWATER 6 2.1 Buckground 2.2 Review of Previous Studies 2.3 Review of the Available Data 2.4 Analysis of Data 2.4.1 Regression Analysis of Groundwater 6 6 11 11 15 Du ta 2.4.2 Depth to Groundwater Hap 2.4.3 Identification of Priority Area of Phase II 2.4.4 Groundwater Salinity Contour Map 16 16 19 2.4.5 Groundwater Level Contour Map 2.4.6 Observation Wells Hydrograph 2.4.7 Piezotuet r ic Sections 19 20 21 2.5 Perched Water Table 23Section Descript ion 2.6 Prediction of Future Groundwater 2.6.1 Rate of Expected Rise 2.6.2 Groundwater Depth 2.6.3 Groundwater Salinity 2.7 Conclusions REFERENCES Page No Depths &. EC in Groundwater 24 29 29 31 31 33 iiTable No LIST OF TABLES Description 1 Number of Observation wells/Piezometers Installed by Individual Organisation and Identifying Codes 2 Status of Observation Weils/Piezometers as on August, 95 3 Wellwise Details of Data Availability 4 Priority Areas Delineated by Depth to Groundwater Contours (Phase-II) 5 Number of Wells Showing Rising or Falling Groundwater Trend 6 Predicted Future Groundwater Depths Below Absolute Zero 7 Predicted Future EC Values 8 Predicted Rate of Rise of Groundwater Level in Wells Having Rising Trend i iiFig No LIST OK FIGURES Description 1 Priority Areas for Sub-Surface Drainage (Phase -II) 2 Groundwater Salinity Contour Map for August,95 EC values 3 Groundwater Levels Contour Map for August 1995 4 Piezometric Cross-Sections (Melka Sadi Area) 5 6 7 8 9 No. 1 2 Piezometric Cross-Sections (Amibara Area) Predicted Groundwater Depth Contour Map f or year 2001 Pred icted Groundwater Depth Contour Map for year 2006 Predicted Groundwater Depth Contour Map for year 2011 Pred icted Groundwater Depth Contour Map for year 2016 LIST OF APPENDICES Description Plot of Annual Observed Maximum, Minimum and Mean Computed Groundwater Depths Plot of Annual Observed Maximum, Minimum and Mean Computed EC values ivHYDROGEOLOGICAL DATA/ANALYSIS 1.0 INTRODUCTION 1.1 Location The area for the drainage study is situated in the Northern Rift Valley region of Ethiopia on the right bank of river Awash. The area covers mainly the settlements in the Melka Sadi and Melka Warer and also includes the Amibara settlement project and state farms. The Addis Ababa-Hille highway provides the access to the project area via an all- weather link road. The Rift Valley Escarpments rise some distance to the east and west of the study area. 1.2 Climate The climate of the project area can be broadly classified as semi-arid, with mean annual rainfall of the order of 563 mm. There are two distinct rainfall pattern, one in July-August covering about 40% of annual rainfall and the other in February - April covering about 32% of the annual rainfall. Heavy intensity rainfall occurs during the rainfall period of July-August but rainfall as high as 100 mm has been observed in one day on March 31,1982. Mean temperature in the project area ranges between 23cC to 31°C with mean maximum temperature of 38°C in June and mean minimum temperature of 14.2°C in December. Mean relative humidity is maximum in August (59% ) and minimum in June (38%). Mean daily sunshine duration is 8.46 hours on annual basis. Mean daily evaporation rates for class ’A* pan is maximum in June (9.49 inm) and minimum in December (6.03 mm). The mean daily evaporation is 7.17 mm on annual basis. 11.3 Soils and Geomorphology According to the Master Drainage Plan for the Melka Sadi and Amibara Area, 1985, prepared by Halcrow, three distinct geomorphological features, namely the recent alluvial plain, a series of ancient fluviatile terraces and volcanic formations of varying age exist in the study area. The alluvial plain is a relatively recent geomorphological feature and shows abundant evidence of construction by fluvial processes, with old meanders and levees being readily identifiable. Adjacent to the alluvial plain are a series of terraces which are most pronounced in the south of the study area, where two distinct terraces can be clearly seen. The higher of these is separated from the alluvial plain by a distinctive escarpment upto 10 metres high. The lower terrace is less pronounced, and both terraces become discontinuous features towards the north of the study area, where isolated remnants are observed. Several irregular volcanic hills rise abruptly from the otherwise flat alluvial plain, and recent lava flows are a common feature in the vicinity of the study area. The generalised soil distribution within the study area reflects the recent geomorphological history. Coarser- textured levee soils occupy a discontinuous belt adjacent to the present river course, with finer textured ’basin’ clays lying beyond this belt and extending towards the higher ground and river terraces in the east. Within this overall pattern, complex soil associations occur, and there is considerable soil variability. Adjacent to the old terraces in the east of the area, occasional patches of saline soils remain, but have largely been excluded from the irrigation development. '*> Elsewhere the soils are of variable but generally low salinity. 21.4 Geology and Hydrogeology The northern Rift Valley was faulted to its present formation during tectonic activity associated with the Tertiary in the late Paleocene - and Eocene Epochs eras. During the subsequent Plio-Pleistocene, outwash gravels containing clay lenses derived from the breakdown products of the elevated areas on the flanks of the Awash River were deposited on the outwash plain adjacent to the river. Intermittent volcanic activity since the Eocene and associated outpourings of lavas has resulted in the deposition of a gravel sequence interbedded with lavas. Towards the present flood plain of the Awash River, these deposits grade into an infill composed of a complex sequence of silts,sandy silts and clays, which have in places been laid to depths exceeding 100m. The general geology of the area has been mapped by Halcrow while preparing the Angelele-Bolhamo Feasibility Study Report in October, 1975. % o The available information show that all formations in the Awash River flood plain are water bearing. The sedimentary materials are consistently fine-grained and characterised by a low horizontal permeability, so that they appear to form an aquifer that is essentially without flow. Aquifer type response is mainly the result of inflow from rainfall and irrigation and outflow by evaporation. Such behaviour precludes the use of deep disposal methods for lowering the water table. Nevertheless, where boreholes have penetrated the gravels or fractured volcanics, water can be extracted in sufficient quantities for water supply purposes. Although confining layers may be encountered locally in fine grained sequence, the groundwater is believed to be in hydraulic contact, regardless of geological formation. 31•5 Irrigation Practices Main crop in the study area is cotton with some banana, maize and other crops. These crops are generally irrigated by gravity canal system taking water from Amibara Irrigation Project. The areas around old Algeta, Ambash and Sublele State Farms, producing cotton were utilizing pumped supplies of irrigation water directly from Awash river through 3 pump units, but now only one pump unit is in working condition. The gravity irrigation system, comprising a network of secondary, tertiary and field canals, designed on the basis of 24 hours operation, takes the water from main canal through offtakes and distribute to the fields. A limited number of flow control and measurement devices have been provided to assist in water management practices. The main method of irrigation is by furrows. Very accurate land grading is required for this type of irrigation system for efficient use of irrigation water. This method of irrigation also requires services of skilled irrigators to maintain correct rates of flow during the period. Basin irrigation system is being practised for the bananas, which require higher water round the year. Basin irrigation system is less sensitive to land grading and, requires less skilled irrigators than furrow method. irrigation 1.6 Draiaage A well planned drainage system is essential to dispose off excess water from the irrigated area which in turn will ensure sustained agricultural production. Surface drainage is required to dispose of excess water due to rainfall whereas sub-surface drainage system may be required to 4control high ground water table and remove excess ground water. At the time of conversion from pumped to gravity irrigation system under Amibara Irrigation Project II, groundwater tables in Melka Sadi-Amibara area were generally at some depth and sub-surface system was not an immediate requirement and only surface drainage system was designed and installed in the project area. Subsequently, due to introduction of irrigation in the study area, groundwater table started rising in certain areas and need for sub surface drainage was felt. Halcrow in 1985 prepared a Master Drainage Plan for Melka Sadi and Amibara Areas,identifying the areas needing immediate surface and sub-surface drainage system under Phase-I and areas needing sub-surface drainage system subsequently under Phase-II and III. On basis of this, the Phase I drainage project was undertaken and is at an advanced stage of completion. The present study needs identifing of the areas needing immediate sub-surface drainage and plan the drainage system for the study areas under Phase II of Amibara Drainage Project. 52.0 GROUNDWATER 2.1 Background Ground Water level observations have been started on intermittent basis in the study area since 1970,since the piezometers were installed by Italconsult and Awash Valley Authority, From 1980, a network of observation wells was installed as a part of the AIP II programme to systematically monitor the ground water levels and salinity of ground water subsequent to the introduction of gravity irrigation in the study area. Since the installation of these piezometers, number of them have been damaged and become unserviceable. Table 1 shows the information about the piezometers installed by the various organizations and Table 2 shows the status of the piezometers as on Aug 95, which indicates that only 54 wells are presently functioning as on Aug, 95. Tn the Melka Sadi and Amibara areas, all observation wells under AIP II which have subsequently been damaged should be repaired or reinstalled and returned to use. 2.2 Review of Previous Studies Italconsult, during the feasibility study of the Melka Sadi -Amibara area in 1969, had indicated the presence of a trough in the water table on the eastern side of the Awash alluvial plain. On either side of this trough, higher water table elevations were observed, indicating some recharge from the river and from the hills bordering the plain. The alluvial plain was believed to consist of a very deep and uniform interbedded sequence of silt, sandy silt and silty sand. 6TABLE 1 - NUMBER OF OBSERVATION WELLS/PIEZOMETERS INSTALLED BY INDIVIDUAL ORGANISATIONS AND IDENTIFYING CODINGS Organisation Which Installed observation Wells/ Piezometers ILalconsult Identifying Code Number Installed PPI,PP5 etc 4 P2,P3 etc 10 DW-ljDW-2 2 Remarks Deep piezometric well (50 m) Shallow piezometric well (15 m) Deep piezometric well (100 m) Awash Valley Authority (A.V.A.) Wp Wj etc 4 No information on installation depths available Sir William lialcrow & Partners Foraky S.A ABS 1.2. etc 15 Piezometers installed by Foraky S.A Amibara Project Irrigation 11 AIP 1.2 etc 67 Piezometers installed to variable depths depending on position of water table. AIP 3/1,3/2,3/3, 10/1,10/2,10/3, etc. 15 Piezometers installed to variable depths observation wells AIP3, AIP 10 etc at a distance of about 5m each. 7TABLE 2. STATUS OF OBSERVATION WELLS/PIEZOMETERS AS ON AUGUST, 95 Observation/ Piezometer Type Reference Number No. of Wells StutUS Italconsult DW-l,DW-2 PPI,PP2,PP5,PP14 P1,P2,P9,P11 P3,4,6,7,8,10,13 2 Not known 4 Not Functionil 4 Functioning 7 Not Function: or Not known 1 Awash Valley Authority (A.V.A) WpWj 4 Sir William Halcrow &. Partners Foraky S.S ABS1 to ABS 15 15 Not Known Amibara Irrigation Project II AIP 4 >9,13,15.20,26, 31,33,36,38,48,53, 17 56,57,58,59,66 Rest AIP 1 to AIP 67 50 Destroyed-0 of use Functioning. 8Sections showing the piezometric grudient of the ground water were plotted by Italconsult which following: indicated the (i) A low hydraulic gradient towards the river in the Melka Sadi area. ii) A low hydraulic gradient away from the river in the Amibara area. iii) A hydraulic gradient of about .1% in a southwest - northeast direction across the Melka Sadi - Amibara area. It was also essentially response to evapotranspiration, concluded by Italconsult that the aquifer was without inflow flow, varying in vertical sense in from precipitation and outflow by ♦s velocity) is of the order of 10 permeability measuremets. Q as groundwater flow velocity(Darcy m/sec based on horizontal Subseque nt studies on geom orphic, geol ogical and ground water studies in the Awash Valley by FAO indicated the possible exis tence of two sets of aquifers below the Amibara Plain. The deeper, unconfined aquifer occupying gravel beds interbedded with lavas and shallow aquifers of variable depth occurring in alluvium above the combined aquifers, recharged by rainfall, floods, the river and from irrigation. In 1975, 15 more piezometers were installed for hydrogeological feasibility investigations during the Angele-Bolhamo study. Hydrogeological investigation largely confirmed the findings of Italconsult. Drainage and salinity studies of Amibara Irrigation I I Project-II carried out by Halcrow, 1982 indicated the existence of perched water tables within 1 to 2m of the 9surface in Melka Sadi area with locally artesian conditions. Halcrow in 1985, during the study of Master Drainage Plan for Melka Sadi and Amibara areas, carried out analysis of the available piezometric data for the wells in the study area. They identified a total area of 3,844 ha ( 2,247 ha in Melka Sadi and 1,597 ha in Amibara) as immediate priority area and a total area of 7,990 ha (4,093 ha in Melka Sadi and 3,897 ha in Amibara area) as the next priority area within next 5 years, based on the ground water depths of 3m and 3 to 6 m respectively. The findings as indicated above were however stated to be indicative of ” the changes likely to take place rather than a definititive statement and should be the subject of revisions as more data becomes available”. Based on the ground water level hydrographs, they observed: (i) Sustained overall groundwater rise of the order of lm per year (ii) The aquifer appears to be responding in a vertical sense to deep percolation losses. The piezometric cross-sections based on May,84 data indicated the following: a) The piezometric surface slopes towards the Awash river with a gradient in the range of 1 in 400 to 1 in 900 in the Melka Sadi area. b) The piezometric surface slopes away from the river, with a gradient of 1 in 400 to 1 in 700 in Amibara area. 10 .--2.3 Review of the Available Data The monthly piezometric observation data of groundwater depths below absosute zero of the piezometer and electrical conductivity below absolute of ground water samples collected from the observation wells were collected for 79 wells in Melka Sadi and Amibara areas for the period from August,1980 to August,1995, with some missing data gaps. Table 3 gives the details of wellwise data availability and the missing data. From Table 3, is observed that almost continuous data for a reasenably long period are available for only 58 wells out of 79 wells. These wells are located in areas A &. C (Phase I), areas B & D (Phase II) and area E (Phase III) but with no well in Area F of phase II,i.e Amibara-Angelele area, where recent data are not available. As per recommendions of the Inception Report accepted by the client, the area F Amibara-Angelele has been excluded from the present study. 2.4 Analysis of Data The consultant in the feasibility study of Melka-Sadi- Amibara Irrigation Project by Italconsult in July, 1969, concluded that the flood plain aquifer, with horizontal permeabilities of 10^m/day, was essentially without flow. The sedimentary materials are consistently fine-grained and characterised by a low horizontal permeability, so that they appear to form an aquifer that is essentially without flow. Aquifer type responses is mainly the result of inflow from rainfall and irrigation and outflow by evaporation. Such behaviour precludes the use of deep disposal methods for lowering the water table. It was further concluded that with ground flow velocities (Darcy’s velocity) in the order of 10’*m/sec (based on horizontal permeability measurements), the aquifer was essentially without flow varying in a vertical sense in response to inflow from precipitation and outflow by evapotranspiration. 11 iTABLE 3 - WELLWISE DETAILS OF DATA AVAILABILITY Sheet 1 of 2 s. NO WELL NO GROUND WATER DEPTH ELECTRICAL CONDUCTIVITY AVAILABILITY FROM TO FULL MISSING YEAR AVAILABILITY FROM TO FULL WUSKING 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Al P-1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 8/80-95 8/80-95 8/80-95 10/80-6/90 8/80-95 8/80-95 8/80-95 8/80-95 8/80-11/91 8/80-95 8/80-95 10/80-95 8/80-9/82 8/80-95 8/80-10/91 8/80-95 8/80-95 8/80-95 8/80-95 8/80-1/95 8/80-95 8/80-95 11/83-95 2/84-95 2/84-95 2/84-94 11/83-95 2/84-95 2/84-95 11/83-95 5/84-2/85 10/80-95 8/80-12/83 9/80-95 8/80-95 8/80-1/89 8/80-95 8/80-6/90 8/80-95 11/83-95 8/80-95 8/80-95 2/84-95 8/80-95 8/80-95 10/80-95 8/80-95 8/80-2/95 8/80-5/95 10/80-95 1984-92 1982 1984 8/80-95 8/80-95 8/80-5/95 10/80-6/90 8/80-95 8/80-95 8/80-95 8/80-11/92 8/80-11/91 8/80-95 8/80-95 10/80-95 8/80-9/82 8/80-95 8/80-10/91 8/80-95 8/80-95 8/80-95 8/80-95 8/80-1/95 8/80-95 8/80-95 6/84-95 6/84-6/93 6/84-8/92 8/84-1/93 7/84-95 6/84-95 6/84-95 1/85-6/91 6/84-1/85 10/80-95 8/80-11/82 10/80-95 8/80-95 8/80-1/89 8/80-95 8/80-10/87 8/80-9/89 3/85-95 8/80-95 8/80-95 8/84-95 8/80-95 8/80-12/94 10/80-95 8/80-95 8/80-2/95 8/80-2/92 10/80-95 1984-92 1982 CM* 12TABLE 3 - WELLWISE DETAILS OF DATA AVAILABILITY Sheet 2 of 2 S. NO WELL NO GROUND WATER DEPTH ELECTRICAL CONDUCTIVITY AVAILABILITY FROM TO FULL MISSING YEAR AVAILABILITY FROM TO FULL MISSING YEAR 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 PPI Pl P2 C5 P8 P9 PIO Pll PP5 P13 PP2 PP9 8/80-95 10/80-95 8/80-1/88 10/80-95 10/80-95 No Data 10/80-4/91 1/85-11/89 No data 10/84-95 6/84-95 10/84-95 10/84-95 11/84-95 11/84-95 2/84-4/91 11/84-95 11/80-12/87 2/82-95 10/80-95 10/80-3/82 11/83-3/86 10/80-95 10/80-11/82 10/80-95 3/82-9/82 11/83 6/84-10/84 1/85-12/85 8/80-95 10/80-95 8/80-1/88 10/80-95 10/80-95 No Data 10/80-4/91 1/85-11/89 No data 10/84-95 6/84-95 10/84-95 10/84-95 11/84-8/93 11/84-95 11/84-4/91 11/84-6/94 12/80-11/84 1/85-7/95 10/80-95 10/80-3/82 1/85-6/85 10/80-95 10/80-11/82 10/80-95 3/82-9/82 No data 6/84-10/84 No data * Note : (i) There are no Electrical Conductivity observations from Dec, 1982 to May, 1984. (ii) No observations are available for any of the wells in respect of ground water depth and EC for the following periods : a) 1981 - July, August &. October. b) 1982 - January, April, July, August, October & December c) 1983 - January to October d) 1984 - March for Groundwater depth e) 1991 - May & June f) 1992 - September (iii) In addition to the above missing data, there are monthly data gaps in the case of individual wells . 13Under such trying circumstances, the mathematical model which is to reproduce the ground water situation at the regional scale, would not be sensitive enough to reproduce the seasonal variation owing to changes in hydrological parameters. Therefore, the available data of groundwater depth were analyzed primarily to delineate the area of immediate priority for the subsurface drainage and a further analysis was carried out to predict the groundwater depths 5,10 &. 20 years and examine the nature of vertical movement of groundwater within aquifer. The reassessment of the area needed to be included in the Phase II had been recommended in the Master Drainage Plan itself as per the following extract from para 4.6, page 40 of Final Report July 1995. ”4.6 Guidelines for the Evaluation of Future Stages of Development The timing of implementation of future stages of subsurface drainage development shall be directly related to the projected rate of encroachment of high watertables. Early implementation of such work, where high watertables are not imminent, would result in a low return on investment. Conversely an excessively delayed implementation could result in lost production and the need for reclamation of the resulting saturated land. Delayed implementation could also exacerbate the difficulties and cost of laying down at 14depth far below the prevailing watertable, particularly in areas of silts or very fine sands where saturated conditions under such water pressures could induce instability. A systematic approach is required based on both monitoring and the evaluation of results leading to the timely planning and implementation of subsequent stages of subsurface drainage.” 2.4.1 Regression Analysis of Groundwater Data Regression analysis of the data of all the 58 wells, irrespective of the location of the well in phase I, phase II and phase III area, for which long term data were available, was carried out to fit the best fit curve. As the groundwater depth varies between maximum and minimum values in the year, the regression was carried out separately for the annual maximum and the minimum groundwater depths. These annual maximum and minimum groundwater depths were plotted for each year on same plot and type of regression, linear (straight line) or non linear (log curve), was selected on the basis of the configuration of the plot. The regression equation so derived was also used for the prediction of the future annual mean groundwater depths after 5,10 or 20 years (years 2001, 2006, 2016). Similar regression analysis was also carried out for the EC data of water samples from each well. Plots of maximum &. minimum groundwater depths and the mean computed depth are shown in Appendix 1 for each well. Similar plots for EC are shown in Appendix 2.2.4.2 Depth to Groundwater Contour Map The groundwater depth contour map for the August 1995 available data (in case no data of August was available for a particular well then data of previous available month, was used) was prepared to identify the areas of immediate priority. The area of immediate priority was taken as the area where groundwater depth is within 3 meters of the ground surface. As the groundwater depths are available below the absolute zero at the top of the piezometer, generally about 30 cm above ground level, a contour of 3.30m was drawn to represent the groundwater depth of 3m below the ground level. 2.4.3 Identification of Priority Area of Phase II To work out the priority areas, the areas enclosed within the contour of 3.30m were rationalized, so that full plot through which the contour is passing, was considered as the boundary of the priority area. Fig 1 shows the priority area based on August 95 ground-water depth contour map. The areas so worked out are given below in Table 4. Although areas B, D & F were to be covered in the study as per terms of reference, the portions of area E also with groundwater less than 3 m below the surface have been shown in the Table 4. Out of the total area of 1,550 ha in Area B of Melka Sadi Area, as per Table 4 above, total 984 ha is proposed to be included as priority area under the present study and 566 ha excluded from the study. Out of this 566 ha,344 ha is excluded because it is already provided with sub-surface drainage system under Phase-I. The balance 222 ha is proposed to be excluded due to low groundwater table. The areas which are not considered for inclusion lie in the northwest part of Area B, where the depth of groundwater 16below the surface is more than 3m. The neighbouring wells in this part of Area B, namely AIP 11, AIP 16 and AIP 19 have all a falling trend of groundwater vide Table 6 and hence the areas proposed to be excluded from priority under phase II, do not seem to have any possible high groundwater level in future as per the present trend. TABLE 4 - PRIORITY AREAS DELINEATED BY DEPTH TO GROUNDWATER CONTOURS (PHASE II) Location Area Zone Priority Area (ha) Remarks Melka Sadi B B A A B - Amibara D D E F C D - - 520 464* 38 Negligible 1552 1400 - Western part of B Eastern part of B Phase-I area where laterals have not been provided North Western Zone of D South Eastern Zone of D - GWL considerably below surface as per old records Total 3974 -1 2 * Excluding part of Area B already//dpv The total area of has been excluded 950 ha of area ed under Phase-I f 'Termss, of Reference from the priority area of Phase II, as 7 proposed client. in the Inception The main reason for that past data indicated the 14m below surface, there 17 Report and accepted by the the exclusion of area F were groundwater level to be about were no tangible irrigatedagriculture in the area and much of the land has soil characteristics not favourable for sub-surface drainage. The Area D has a total area of 3,050 ha, out of which as per Table 4 above, 1,552 ha is to be included under priority area of Phase II. The area proposed to be included lies in the south eastern part of Area D. On the other hand, in the Zone C in the northwest of area D, the groundwater level is more than 3 m below the surface, and in general the trend is of falling groundwater level. In general the change in the trend of variation in groundwater level occurred in the year 1989-90. The pumped irrigation in the area started diminishing since 1992-93 and hence the trend of falling groundwater table cannot be attributed to be solely due to the reduction of irrigated area. The aforesaid change in the trend seem to be similar to the gravity irrigated areas, where the change in trend occurred on introduction of during the period 1989-90. irrigation through alternate furrows It is, therefore, debatable as to whether the present falling trend of groundwater level in the zone C of area D will reverse on reintroduction of pumped irrigation in this zone in the coming years. Even conceding that there could be a change in the trend of falling groundwater level on reintroduction of extensive pumped irrigation, it is evident that it will take considerable time to reach the critical groundwater depth of 3m below the surface. It is found that the observation well readings in 1995 in this zone are comparable with readings during 1985 and in the Master Drainage Plan 1985 on the basis of these readings it was concluded that this zone did not need immediate subsurface drainage. Hence there is every justification to exclude this zone from the priority area of Phase II. 18As per terms of reference, the area E of 2,340 ha is not to be covered under the present study. However, as per clients request, the groundwater levels in area E were also studied and it was found that a substantial area of 1,400 ha of area E has grounwater level less than 3 m below surface and this area is in continuat-ion of the priority area of Area D. Hence, the 1,400 ha of Area E could also be included under priority area of Phase II 2.4.4 Groundwater Salinity Contour Map Groundwater salinity measurements are based on the determination of the electrical conductivity of water samples collected from the observation wells. The availability of EC data of groundwater wellwise is shown in Table 3. The continuous observation of EC is available from June, 1984 onwards for almost all functioning wells. Groundwater salinity contour map has been prepared for the August 1995 EC values (Fig 2). From the map it is observed that EC values varies in the range of 4 to 12 mmho/cm in Melka Sadi area. In Melka Sadi Phase - II area, EC values varies in the range of 4-8 mmho/cm. In Amibara area, EC values varies in the range of 2 to 12 mmho/cm. 2.4.5 Groundwater Contour Level Map Groundwater levels for each well for August, 1995 were computed by subtracting groundwater depth below absolute zero from the absolute zero value of the corresponding well. Ground water contour map (Fig 3) for Aug 1995 levels was then developed to study the predominant flow directions. In the immediate vicinity of Awash river, the observation well network is such that accurate positioning of groundwater contours was not possible. 19Therefore, contours were not extended upto the river as it could not be identified definitely as to whether the river acts as a source of groundwater recharge or as a sink for groundwater release. From the groundwater contour map (Fig 3), it is observed that the groundwater gradient direction is mainly from the southern part of the eastern dyke towards the northwest part of the river dyke in the Melka Sadi area. In Amibara area, from the groundwater contour map, a hydraulic gradient line, generally parallel to the eastern dyke can be traced as a minor trough, almost from the southern end to the northern end, water table on east and west of which are higher. A low ground-water zone like a sink can be located around observation well no. AIP 63 in the Amibara Settlement Project Area. The hydraulic gradient line of ground-water slopes towards this sink both from river side in the south and west as well as from the land side on the east and north. Unlike Melka Sadi area, in the Amibara area, there is no general slope of the groundwater towards the river. 2.4.6 Observation Well Hydrographs As already mentioned in section 2.4.1, observation well hydrographs were drawn for the annual maximum and minimum groundwater depth and groundwater EC values to analyze the variation of the groundwater depths and EC values from year to year and also to carry out regression analysis for the prediction under future scenarios. The hydrographs for 58 wells, for which long term data from 1980 to 1995 were available and regression analysis carried out, have been shown in Appendix 1 for groundwater depth and Appendix 2 for groundwater EC values. 20From the observation well hydrographs, it is observed that for 42 number of wells, groundwater depth is increasing or groundwater level is having a falling trend. For most of the wells the falling groundwater trend has started from the year 1989/90. In case of EC values, 20 number of wells show the falling trend of groundwater salinity. Areawise details of wells showing rising or falling groundwater trend is given in Table 5. The change in the trend of groundwater level variation from 1989/90 onwards in most of the cases of Appendix 1 may be attributed to the changes in the irrigation practices introduced during this period by supplying water to alternate furrow instead of each furrow, thereby reducing the total quantity of irrigation water supplied and to some extent also due to area being not cultivated. The yearwise quantity of irrigation water supplied offtakewise along with area irrigated are reviewed in Annex 12, dealing with Data on Agricultural Aspects. From this, it is observed that in recent years, total water applied per hectare has reduced, which seems to be one of the main reasons for falling groundwater trend. This is discussed in more detail in Annex 12. From the items A3 and B7a of Table 5, it can be seen that in Phase I areas, almost all the observation wells show falling groundwater level trend, indicating that the sub surface drainage provided under Phase I are proving e f fect ive. 2.4.7 Piezometric Sections In the Master Drainage Plan (Halcrow,1985), piezometric section, approximately perpendicular to the groundwater contours and intersecting selected observation wells were plotted for both Melka Sadi & Amibara areas (Fig 4 & 5)* 21TABLE 5 - NUMBER OF WELLS SHOWING RISING OR FALLING GROUNDWATER TREND s. No Area 8c Zone Number of Wells With GW Trend Well No. Rise- ing Fall ing A 1 2 3 Melka Sadi Zone A of Area B Zone B of Area B Other Area a) Phase I 3 1 1 5 1 16 B 4 5 6 7 * b) Outside Phase I&II Anibara Zone C of Area D Zone D of Area D Zone E of Area E Other Area a) Phase I b) Outside Phase II 1 AIP 5,9,11,30 AIP 18,19,20,21, 22, PP1/P1 AIP 2,3,6,7,8. 10,12,14,17,23, 24,25,26,27,28, 29, Pll AIP 16 3 - 5 2 8 2 1 7 1 1 AIP 44, 49, 55,62, P9 AIP 34,35,37, 41,42, 43,64,65 AIP 46,47,50,51 52,54,67 AIP 32,39,40,45, 60,61, 63,P2 AIP 48,57 Total 15 43 22based on May 1984 observat ion wells data with river bed levels based on available topographic surveys, Identical piezometric cross-sections were taken from groundwater contour map discussed in section 2.4.5 and superimposed on Figure 4 & 5. The following observations can be made from the piezometric cross-section : (1) In Melka Sadi area, the piezometric surface slopes towards river Awash with a gradient approximately in the range of 1 in 600 to 1 in 2500 along the selected cross-sections. With the assumed average depth of 6 m above bed level at Melka Warer site for August for the flood condition, the ground water flow direction will be away from the river and positive head is available for recharge from river to groundwater. (ii) In Amibara area, the piezometric surface slopes away from the river along section D-D and section F-F with a gradient in the range of 1 in 600 to 1 in 1000. Along section EE, the piezometric surface slopes from southern side (eastern dyke side) towards river on northern side. 2.5 Perched Water Tables Within the Melka Sadi area, the possibly-existence perched water tables, separated from true deeper ground water by an impermeable layer of varying thickness was noted in previous studies on Drainage & Salinity of AIP II carried out by Halcrow (1982). The field soil survey conducted by Halcrow (1985), while preparing Master r.f ' Drainage Plan of Melka Sadi &. Amibara areas, has indicated 23that the relatively impermeable layer was such that perched water tables extending over a considerable area exists in Melka Sadi area. In Amibara area occurrence of perched water table was indicted to be of very limited extent. Relatively impermeable layer was defined as one whose hydraulic conductivity is less than ten times that of the soil horizon immediately above irrespective of soil textural group. In a highly stratified soils the relatively impermeable layer can be readily identified as a compact layer of silty clay or clay of considerable continuous lateral extent. The detailed soil survey of the identified priority areas in Melka Sadi and Amibara was also carried out by the consultants! the detailed description of which is given in Annex 4 dealing with Soil Survey/Soil Classification data/Analysis. The field soil survey has indicated the existence of perched water table as discussed in Annex D. 2.6 Prediction of Future Groundwater Depths and EC As already mentioned in section 2.4.1, regression analysis was carried out for all the 58 wells for which long term data were available, irrespective of whether the well is located in phase- II area or outside it. The regression analysis was carried out for both groundwater depth as well as groundwater EC values. Based on the regression equation, predictions were done for a period of 20 years hence( ie upto 2016. The extrapolation was terminated either at 20 year or when the predicted depth to ground water reaches near surface or EC values become almost zero. Table 6 shows the mean predicted groundwater depths for each well for the years 1996, 2001, 2006, 2011 and 2016. 24TABLE 6 - PREDICTED FUTURE GROUNDWATER DEPTHS BELOW ABSOLUTE ZERO s. No Well No Absolute Zero Value (■) GW Depth for the Year (■) Area Location 1996 2001 2006 2011 2016 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 42 44 Al P-2 ” -3 " -5 ” -6 " -7 ” -8 ” -9 " -10 " -11 ” -12 " -14 ” -16 ” -17 " -18 ” -19 " -20 " -21 ” -22 ” -23 " -24 ” -25 ” -26 " -27 " -28 " -29 " -30 " -32 " -34 " -35 ” -37 " -39 ” -40 " -41 " -42 " -43 ” -44 " -45 ” -46 " -47 " -48 ” -49 " -50 " -51 ” -52 743.82 743.60 741.42 744.40 740.96 740.996 739.89 741.233 739.89 738.64 742.32 739.20 739.83 741.48 738.94 738.75 737.30 737.72 740.58 740.12 740.26 741.03 746.09 744.58 742.65 735.53 735.48 734.12 733.52 733.44 732.66 732.56 731.64 731.43 732.09 730.26 731.33 730.15 735.875 729.13 728.74 727.86 730.14 2.77 2.17 2.44 2.47 3.73 4.86 0.80 3.30 4.42 3.71 3.18 7.94 3.22 3.06 4.07 3.23 3.77 2.52 3.65 3.85 5.19 5.05 3.01 3.63 4.09 1.49 6.86 3.38 2.61 2.23 7.32 5.79 6.21 3.13 2.5 5.49 5.64 4.91 2.11 3.20 2.35 3.95 3.16 7.24 4.1 2.43 2.41 2.26 4.96 5.99 0.36 3.90 5.74 5.97 4.24 11.39 4.39 3.58 4.63 3.90 4.88 2.71 4.97 4.85 7.65 7.51 2.68 4.98 5.61 1.65 8.87 4.33 3.3 2.29 7.42 8.21 9.60 3.85 2.74 7.39 8.45 6.42 0.36 (1998) 2.21 1.60 5.52 0.13 5.28 5.43 2.70 2.38 2.05 6.79 7.12 0.16 4.49 7.06 8.23 5.3 14.84 5.57 4.10 5.18 4.57 5.98 2.90 6.29 5.85 10.12 9.97 2.34 6.33 7.13 1.80 10.89 5.28 3.99 2.34 7.53 10.63 12.99 4.58 2.99 9.29 11.25 7.93 1.23 1.09 7.08 3.31 6.76 2.96 2.35 1.84 7.42 8.24 0.08 5.09 8.38 10.48 6.36 18.29 6.75 4.62 5.74 5.23 7.09 3.09 7.61 6.85 12.58 12.42 2.01 7.68 8.65 I. 95 12.91 6.23 4.68 2.39 7.63 13.05 16.37 5.31 3.23 II. 18 14.06 9.45 0.32 0.75 £.64 1.35 8.09 3.23 2.31 1.63 8.65 9.37 0.04 5.69 9.70 12.74 7.41 21.74 7.92 5.14 6.29 5.90 8.20 3.28 8.93 7.85 15.05 14.88 1.68 9.04 10.17 2.10 14.92 7.18 5.37 2.44 7.74 15.47 19.76 6.03 3.48 13.08 16.87 10.96 0.52 10.21 A A B A A A B A B A A B A B B B B B A A A A A A A B C D D D C c D D D D C E E Outside D E E E 25TABLE 6 - PREDICTED FUTURE GROUNDWATER DEPTHS BELOW ABSOLUTE ZERO s. No Well No Absolute Zero Value (■) GW Depth for the Year (■) Sheet 2 of 2 n 1996 2001 2006 2011 Area Location 2016 45 46 47 48 49 50 51 52 53 54 55 56 57 58 A1P-54 “ -55 11 -57 " -60 " -61 " -62 " -63 " -64 " -65 " -67 " -Pl ’’ -P2 ” -P9 ” -Pll 728.30 726.99 726.17 735.02 731.03 728.14 734.52 732.96 733.26 729.83 738.27 735.55 728.27 741.96 9.39 4.87 4.68 3.91 3.92 3.89 12.23 2.81 5.79 4.37 3.97 10.73 5.46 3.32 7.20 6.36 3.04 1.14 5.35 5.34 16.38 3.57 8.9 6.23 2.88 14.11 5.3 4.77 5.02 7.84 1.99 6.77 6.79 20.53 4.32 12.02 8.09 1.79 17.49 5.14 6.22 2.84 9.32 1.30 8.2 8.23 24.67 5.07 15.14 9.96 1.31 20.86 4.99 7.67 0.87 10.8 0.86 9.62 9.68 28.82 5.82 18.26 11.82 0.91 24.24 4.83 9.11 E b outside C C D C D D E B C D A n ii ii li 26TABLE 7 - PREDICTED FUTURE EC VALUES I S. No Well No Absolute Zero Value (■) EC Value for the Year (aaho/Ca) 1996 2001 2006 2011 2016 Sheet 1 of 2 Area Location 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 Al P-2 ” -3 " -5 ” -6 " -7 " -8 " -9 " -10 " -11 " -12 " -14 " -16 ” -17 ” -18 ” -19 ” -20 " -21 " -22 " -23 ” -24 ” -25 " -26 ” -27 ” -28 " -29 ” -30 " -32 ” -34 " -35 " -37 ” -39 " -40 " -41 " -42 " -43 " -44 " -45 " -46 " -47 " -48 ” -49 " -50 743.82 743.60 741.42 744.40 740.97 740.996 739.89 741.233 739.89 738.64 742.32 739.20 739.83 741.48 738.94 738.75 737.30 737.72 740.58 740.12 740.26 741.03 746.09 744.58 742.65 - 735.53 735.48 734.12 733.52 733.44 732.66 732.56 731.64 731.43 732.09 730.26 731.33 730.15 735.875 729.13 728.74 1.87 2.37 4.80 3.44 13.72 18.56 29.43 7.66 8.27 5.39 6.8 8.66 1.95 10.10 7.22 1.54 6.62 12.92 7.11 1.30 2.23 1.59 7.25 5.23 15.97 2.21 5.44 2.97 5.41 4.04 28.42 7.41 6.15 10.85 7.94 12.36 2.21 5.41 10.15 3.38 5.68 9.11 2.24 2.91 5.56 4.04 11.99 26.56 36.03 9.33 10.88 8.55 7.98 10.13 1.89 11.13 7.22 10.0 6.68 13.88 7.02 0.69 2.68 1.92 8.27 7.08 23.37 2.73 7.36 2.93 0.62 (2000) 4.68 39.05 9.83 5.43 8.65 9.38 7.37 2.67 0.39 (1998) 9.46 2.31 1.16 (1999) 4.57 2.62 3.45 6.33 4.65 10.26 34.55 42.63 11.00 13.49 11.71 9.16 11.59 1.83 12.17 7.22 - 6.75 14.85 6.93 0.76 3.14 2.25 9.29 8.93 30.77 3.26 9.28 2.89 - 5.33 49.69 12.25 4.71 6.45 10.82 3.32 3.14 - 8.76 2.51 - 1.33 2.99 3.99 7.09 5.25 8.52 42.55 49.24 12.68 16.10 14.87 10.34 13.06 1.77 13.20 7.22 - 6.81 15.82 7.02 0.83 3.59 2.59 10.3 10.79 38.17 3.78 11.2 2.88 - 5.98 60.32 14.66 4.31 4.25 12.26 0.84 3.60 - 8.06 2.72 - 0.69 3.37 4.53 7.86 5.86 6.79 50.55 55.84 14.35 18.71 18.03 11.52 14.52 1.71 14.24 7.22 - 6.88 16.79 8.17 0.90 4.04 2.91 11.3 12.64 45.57 4.30 13.11 3.01 - 6.62 70.96 17.08 4.51 2.05 13.7 — 4.07 - 70.36 2.93 - 0.36 A B A A A B A B A A B A B B B B B A A A A A A A B C D D D C C D D D D C E E Outside D E 27TABLE 7 - PREDICTED FUTURE EC VALUES Sheet 2 of 2 s. No Well No Absolute Zero Value (■) EC Value for the year (anho/ca) Area Location 199G 2001 2006 2011 2016 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 Al P-51 " -52 " -54 " -55 ’ -57 " -60 ” -61 ” -62 11 -63 " -64 ” -65 " -67 " -Pl ” -P2 ” -P9 " -Pll 727.86 730.14 728.30 726.99 726.17 735.02 731.03 720.14 734.52 732.96 733.26 729.83 738.27 735.55 728.27 741.96 8.73 6.84 6.66 3.33 34.48 3.63 5.92 6.42 5.18 3.69 4.55 1.34 3.44 3.9 2.88 7.47 1.51 4.47 7.82 3.86 43.9 3.46 8.14 8.48 5.37 3.72 5.04 0.52 4.48 3.41 0.42 5.49 0.1 (2004) 2.1 8.98 4.39 53.26 3.29 10.36 10.55 5.56 5.08 5.54 0.19 5.51 4.11 0.13 (2003) 3.51 0.47 10.15 4.93 62.66 3.12 12.58 12.61 5.75 6.43 6.03 0.05 (2008) 6.54 4.81 1.52 0.1 (2013) 11.31 5.46 72.05 2.95 14.8 14.68 5.94 7.79 6.53 7.57 5.51 0.92 E E E D outside C C D C D D E B C D A 20Table 7 shows the mean predicted EC values for the same years. Based on the above predicted values, contour maps have been prepared for the years 2001, 2006, 2011 and 2016 for groundwater depths (Fig 6 to 9). Prediction for future years has been done on the present trend and the assumption that similar trend will continue in future also. 2.6.1 Rate of Expected Rise in Groundwater Out of the 58 number of wells in Table 6, only 14 number of wells have indicated a trend of rise in groundwater level and the remaining 44 number of wells have a trend of falling groundwater level. Thus only 24 percent of the wells have a trend of rising groundwater level. In Table 8 the annual rate of rise in groundwater level have been worked out which is maximum 0.88 m/year, minimum 0.01 m/year and average 0.29 m/year. This finding is considerably different from the assessment made in the Master Drainage Plan 1985 where it was assessed that the overall rate of rise in groundwater level shall be lm/year. This modified rate of rise in groundwater level means that areas, where the groundwater is at 3 m below the surface and there is a rising trend, in general the groundwater level shall attain a critical depth of 2m below the surface in a period of 3 to 4 years. With the experience of the time needed to complete the implementation of the Phase I which has an area comparable with Phase II area, it would be reasonable to consider area with groundwater level upto 3m below the surface, as the priority area. 2.6.2 Groundwater Depth From the groundwater depth contour maps it is observed that 29TABLE 8 PREDICTED RATE Ob' RISE OF GROUNDWATER LEVEL IN WELLS HAVING RISING Well No Ground Water depth for the year 1996 2001 Rise in Ground Water level in 5 years (■) Annual rate of rise ■/year A1P 5 A1P 6 Al P 9 Al P 27 AIP 47 AIP 48 AIP 49 AIP 51 AIP 52 AIP 54 AIP 57 AIP 60 P1 P9 2.44 2.47 0.80 3.01 2.11 3.20 2.35 3.16 7.24 9.39 4.68 3.91 3.97 5.46 2.41 2.26 0.36 2.68 0.36 2.21 1.60 0.13 5.28 7.20 3.04 1.14 2.88 5.30 0.03 0.21 0.44 0.33 1.75 0.99 0.75 3.03 1.96 2.19 1.64 2.77 1.09 0.16 0.01 0.04 0.09 0.07 0.88 0.20 0.15 0.61 0.39 0.44 0.33 0.55 0.22 0.03 Total 4.01 Average 0.29 30most of the area in Melka Sadi, which at present have groundwater at 3 m below ground will have prog-ressively increasing groundwater depth from year to year. In case of Amibara area also, areas having groundwater depth within 3m will reduce in Area D Zone C and Area D Zone D. Some additional area in Area E around wells AIP 47, 51 , 52, 54 & 57 will have groundwater depths within 3 m range in future, which will require sub-surface drainage system if the present trend of rising groundwater continues but that situation will arrive only after about 5-15 years from now and hence can not be included in the priority area of Phase JI . 2.6.3 Ground Water Salinity From the Table 7, it is observed that 13 wells out of 22 wells in Phase II area have rising groundwater salinity trend. Groundwater salinity will increase in the entire Area B-Zone A. In Area B-Zone B, except wells AIP 19 &. 20 others wells have shown rising EC trend. In Zone C-Aree D, wells AIP 55 &. 62 have shown the marginal rise in EC values. In Zone D-Area D, wells AIP 37, 43 &. 65 have shown the small increase in EC values. In Area E except well 54 alL the wells have shown falling EC trend and EC reducing to almost zero in most of the case. 2.7 Conclusions The magn itude of sub-surface field drainage priorit y areas within the phase -II (Area B and Area D) asse ssed on the basis of August, 95 groundwater depths is 2,536 ha which is much less than the area shown in TOR as 5,000 - 6,000 ha. Even if some additional area requiring sub-surface drainage in Area A and E, which is outside the scope of TOR, is also 31included then total area for sub-surface drainage works out to 3,974 ha only for which consultants propose to design the sub-surface drainage system. Attempt to increase the aforesaid area identified as priority area by adding to it some areas having groundwater more than 3m below the surface will adversely affect the economic viability of the Phase II project due to the reason quoted from the Master Drainage Plan 1985, at section 2.4. 32APPENDIX 1 ■DEPTH(m) ■■aas■ G.W. DEPTHS FOR WELL-2 1980 1984 1988 1992 e" □ MAX + 1996 2000 2004 2008 2012 201 l YEAR MIN X MEAN(C).DEPTH(m) □ MAX YEAR Mlbl MEAN(C)DEPTH(m) MAX.& MIN.DEPTHS FOR WELL-5 YEAR □ MAX. + MIN X COMP(MEAN)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS FOR WELL-6 8 1980 1984 1988 1992 1996 YEAR 2000 2004 2008 2012 2016 □ MAX + MIN X MEAN(C)G.W.D.(m) MAXIMUM & MINIMUM G.W.DEP'THS YEAR □ MAXIMUM + MINIMUM X COMP (MEAN)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 10 □ MAX YEAR MIN X MEAN(C)EC(mmho/cm) MAX.& MIN. EC VALUES<.'LUO/oqujLU)03 MAXIMUM & EC VALUES /'J 1984 20U*d o MAX 1988 1992 1996 Y E- + MillEC(mmho/ zcrrQ MAXIMUM & MINIMUM EC VALUES FOR WELL—1 1 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 1980 1934 1988 1992 1996 2000 2004 2003 2012 2016 YEAR □ MAXIMUM + MINIMUM O MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES -.FOR WELL-12 1980 1984 1988 1992 1 996 2000 2004 2003 20 I 2 20 It YEAR □ MAX MiH X MEAN(C)EC(mmho/cm) MAX.& MIN. EC VALUES 12 YEAR □ MAX + MIN X MEAN(C)EC(rnmho/'cm) MAXIMUM & MINIMUM EC VALUES YEAR □ MAX + MIN X MEAN(C;EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES 12 □ MAX YEAR MIN X MEAN(C)(IJJO/OLI LU 1X1)023 MAXIMUM & MINIMUM EC VALUES FOR WELL-18 18 -------------------------------------------------------------------------------------------- 1 ii iI—|---------- i------ ii—II---------1------- i------ i—i---------- 1-------1-- f----- ii-1II-1i—i------------------ii—iI--------- 1--- 1----- l—|---------- II—i»---------1------]—i » • | —l r 1980 1984 I 988 1992 1996 2000 2004 2008 201 2 2016 YEAR □ MAX + MIN X MEAN(O)EC(rnmho/cm) MAXIMUM & MINIMUM EC VALUES 12 □ MAXIMUM YEAR + MINIMUM X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES 45 □ MAXIMUM YEAR MINIMUM X MEAM(C)EC(mmho/'cm) MAXIMUM & MINIMUM EC VALUES YEAR □ MAX -I- MIN X MEAN(C)EC(rnmho/cm) MAXIMUM & MINIMUM EC VALUES FOR WELL—22 23 3------------- i----- t----- r----- 1-----1---- tr—IIr—II------ Tr—1t-----t----- j----- t----- tr—it------ |------ T---- t------ t----- 1-----t------ t------ t |-------------t------ t t | tr—it r 1984 1988 f *' 1992 1996 2000 2004 2008 2012 2016 YEAR □ MAX H- MIN X MEAN(C) fffEVKIIIIIIEC(mmho/crn) MAXIMUM & MINIMUM EC VALUES 34 □ MAX YEAR MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES YEAR □ MAX + MIN X MEAM(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES YEAR □ MAX + MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES 3 □ MAX YEAR MIN X MEAN(C)(UJ 5/O 4 LULU ) 03 MAXIMUM & MINIMUM EC VALUES YEAR □ MAX + MIN X MEAN(C)( ijj o/o q lulu ) 03 MAXIMUM & MINIMUM EC VALUES FOB WELL—28 0 r " i [ i : i | i i i |" r r i" | i i i j i i | I I i i “j i i » j i ■ i 1980 193 + 1988 1992 1995 2000 2004 2008 2012 2016 YEAR □ MAX + MIN X MEAN(C) BKBBBBBSSS(LU 0/0 4 LU LU ) 03 MAXIMUM & MINIMUM EC VALUES 60 MAX YEAR MIN X MEAN(C)(LUO/OULU LU) 03 MAXIMUM & MINIMUM EC VALUES YEAR □ MAX + MIN X MEAM(C)(luo/0 4luuj)03 MAXIMUM & MINIMUM EC VALUES YEAR □ MAX + MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES 14 □ MAXIMUM YEAR MINIMUM X MEAN(C)(uuo/oqLuuj)03 MAXIMUM & MINIMUM EC VALUES 26 □ MAX YEAR MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES □ MAX YEAR MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES so □ MAX YEAR MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES 1980 1984 1988 1992 1996 2000 2004 2008 2012 2016 YEAR D MAX + MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES 11 □ MAX YEAR MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES □ MAX YEAR MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES MAX YEAR + MIN X MEAM(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES FOR WELL-44 40 --- ---------------------------------------------------------------------------------------------------------------------------------- 0-------- 1—i—i—|—i------ 1—i—j—»—’—i—|—’—'—i—|—’—»—i—j—•—'—’—|—’ 1 ’ i ’ * T T 1980 1984 1988 1992 1996 2000 2004 2008 2012 YEAR 2016 □ MAX + MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES FOR WELL—45 □ MAX + YEAR MIN MEAN(C)EC(mmho/cm) ! MAXIMUM & MINIMUM EC VALUES 2000 □ MAX + MIN X MEAM(C) I f I ■ ■ s a a uux ■ -DEPTH(m) MAXIMUM & MINIMUM G.W. DEPTHS □ MAXIMUM + MINIMUM X COMP(MEAN)DEPTH (m) MAXIMUM 8c MINIMUM G.W.DEPTHS 6 □ MAX YEAR MIN X MEAN(C)DEPTH (ni} MAXIMUM & MINIMUM G.W.DEPTHS MAX YEAR 4- MIN X MEAN(C)DEFTH(m) MAXIMUM & MINIMUM G.W.DEPTHSDEPTH MAXIMUM MINIMUM G.W.DEPTHS c □ MAX 4- MIN X MEAN(C)DEPTH(m) KIUIU*4J IMUM &c. MINIMUM G.W.DEPTHS FOR WELL-16 22-------- 21 - 20 - 19 - 18 - 17 - 16 - 15 - 14 - 13 - 12 - 11 10 ip-Q, 9 8- 7- 6- 5- 4 H. 1980 T 1996 2000 YEAR MIN X MEAN(C)DEPTH(m) MAX YEAR MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS □ MAX YEAR MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.'//.DEPTHS FOR WELL-19 10 -i------------------------------------------------------------------------------------- ------------------------------------------- 1 ’ i---------- 1----- ]------1-1-’1'-—' ----11---'-- J----- J----- 1----------11--------- ]1---------- 11------rr——it------ j1---i--1----- tr-—1 ---- 1-----1j-—I ----- 1----- 1—1 -----—1 1---—f -- 1-—1 ---- 1—1----—1 - 1-—1 - 1—-- j------ 1----- 1----- 11-----Jj------ 11-----1—r 1 1984 1988 e-- 1992 1996 YEAR 2000 2004 2008 2012 2016 □ MAX + MIN X MEAN(C)DEPTH(m) MAXIMUM &. MINIMUM G.W. DEPTHS YEAR + MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W. DEPTHS FOR WELL-21 13 1 ’ ’I' 1r] ’ 1 1 | ’ 1 ' i |----------------- T---------- 1 ----- 1----- 1----- 1----- 1----- 1----- 1----- 1----- 1----- 1----- 1------1----- 1 ----- 1----- 1----- 1----- r 1980 1934 1988 1992 1996 2000 2004 2008 2012 2016 □ MAX + YEAR MIN X MEAN (C)DEPTH(m) MAXIMUM & .MINIMUM G.W.DEPTHS YEAR + WIN X MEAN(C)DEPTH(m) MAXIMUM G.W. DEPTH c_ '.y FOR WELL—23 9 -i— 8- 7- X X 6- X 5- 4- 3- 2- i -H 1980 1984 1988 1992 1996 2000 2004 2008 2012 2016 * □ MAX + MIN X MEAN(C) YEARDEPTH(m) > Alt-J* - ■■ MAXIMUM & MINIMUM G.W.DEPTHSDEPTH(m) 1980 1984 1988 1992 1996 2000 2004 2008 2012 201c r-' □ MAX 4- MIN X MEAN(C) YEARDEPTH(m) G.W.DEPTH FOR WELL-26 15 1980 1984 1988 1992 1996 2000 2004 2008 2012 2016 f *' D MAX YEAR MIN X MEAN(C)DEPTH(m) FOR WELL—27 5 4.8 4.6 4.4 4.2 4 3.8 3.6 3.4 3.2 3 2.8 2.6 2.4 2.2 2 1.8 1.6 1980 1984 1988 □ MAX 1992 1996 YEAR MIN 2000 2004 2008 2012 2016 X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 13 1980 1934 1938 1992 1996 2000 2004 2008 2012 2016 YEAR □ MAX MIN X MEAN(G)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 11 MAX YEAR MIN X MEAN(C) __DEPTH(m) MAXIMUM & MINIMUM G.W. DEPTHS 6 □ MAX YEAR MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS FOR WELL-34 10 . 1 ’ I' I ir—“ii | i----------- ir—ii------- j--------i------ 1----- 1----- |------ r 1980 1984 1988 1992 1996 2000 2004 2008 2012 2016 □ MAX 4- YEAR MIN x MEAM(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS YEAR X MEAN(C)DEPTH(m) MAXIMUM & G.W. DEPTHS □ MAX YEAR MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS FOR WELL—37 1 --- ’ I ' —. | r—i ------ 1----- j------ 1----- r — '—1—1—r 1996 YEAR —I—1— — i—j—i—i—i— |—i— T-- t--- J « 1980 1934 1988 1992 2000 2004 2008 2012 —— 2016 □ MAX + MIN X MEAN(C)DEPTH(m) 1980 1984 1988 1992 '.-.'1996 2000 2004 2008 • 2012 201c YEAR □ MAX + MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS FOR WELL-40 16 -- 15 - 14 - 13 - 12 - 11- 10 - 9- 8- 7- 6- 5- 4- 3- 2- -Lx X 5 •• X 1 4- 1930 1996 2000 YEAR 2004 X MEAN(C) •r-----1---- j----- 1-----1---- 1---- 1----- 1i—ii r 2003 2012 2016DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHSDEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 14 □ MAX YEAR MIN mean(c)DEPTH(m). MAXIMUM & MINIMUM G.W.DEPTHS 12 □ MAX YEAR MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS FHR WFLI-44 14 MAX YEAR + MIN X MEAN(C)DEPTH (rrr) MAXIMUM & MINIMUM G.W. DEPTHS FOR WELL—45 1177 16 15 14 13 12 1111 10 9 B 7 6 5 4 33 2 11 0 1980 1984 1988 11999922 11999966 22000000 22000044 22000088 22001122 1 n YEAR MIN MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 17 □ MAX YEAR + MIN X MEAN(C) ■r U w g B H sDEPTH(rn) MAXIMUM & MINIMUM G.W.DEPTHS YEAR □ MAX + MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS FOR WELL—48 7 2- 1 1980 1 I 1 1 -n------- 1-----t---- —1—1—'—r —--------1---- 1---- r —'—1—’— —»—iiiiiiiiiii ||—i— 1934 1988 1992 1995 YEAR MIN 2000 2004 2008 i | f—n 2012 2016 □ MAX + X MEAN(C)DEPTH(m) MAX YEAR -I- MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W. DEPTHS 13 YEAR □ MAX + MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 16 □ MAX + YEAR MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W. DEPTHS 14 YEAR □ MAX + MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 17 FOR WELL—54 1980 1984 1988 1992 1996 2000 2004 2008 2012 ' 2016 YEAR □ MAX 4- MIN X MEAN(C)DEFTH(m) MAXIMUM & MINIMUM G.W.DEPTHS □ MAX YEAR MIN X MEA.N(C)DEPTH(m) MAXIMUM 8c MINIMUM G.W.DEPTHS FOR WELL—57(LOG) 1--- ----- 1---- 1---- 1---- r- —1— 1— ----- 1---- 1--- - ’----- 1---- 1---- ]----- 1---- r — .—|—i— 2000 —i—i—i—i—i—i —i— • 1 • 1 1980 1984 1988 1992 1996 2004 2008 2012 201 6*^ • YEAR □ MAX + MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 9 □ MAX YEAR MIN X MEAM(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS MAX YEAR + MIN X MEAN(C)DEPTH (m) MAXIMUM & MINIMUM G.W.DEPTHS 10 MAX + MIN X MEAN(C)DEPTH (m) MAXIMUM & MINIMUM G.W.DEPTHS 30 MAX YEAR MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 8 FOR WELL—64 1996 2000 YEAR MIN 2008 X MEAN(C) ■mJ -I I I II 3DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 1980 1984 1988 1992 . 1996 2000 2004 2008 YEAR 2012 2016 □ MAX 4-* MIN X MEAN(C) 4DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS □ MAX YEAR MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 12 YEAR □ MAX + MIN X MEAN(C)DEPTH (m) I MAXIMUM & MINIMUM G.W.DEPTH □ MAX YEAR MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 13 □ MAX YEAR MIN X MEAN(C)DEPTH(m) MAXIMUM & MINIMUM G.W.DEPTHS 10 □ MAX + YEAR MIN X MEAN(C)APPENDIX 2{ujo/oqujLu)33 MAXIMUM & MINIMUM EC '/CLUES 3.4 YEAR □ MAX 4- MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUESEC(mmho/crn) MAXIMUM & MINIMUM EC VALUES YEAREC (mmho/cm) MAXIMUM & MINIMUM EC VALUES 30 YEAR □ MAXIMUM + MINIMUM X COMP(MEAN)EC(mmho/crn) MAXIMUM & MINIMUM EC VALUES □ YEAR -t- MIN X MEAN(C)EC(mmho/cm) MAX.& MIN. EC VALUES YEAR □ MAX + MIN X COMP (MEAN)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES FOR WELL—47 1980 1984 1988 1992 1996 2000 2004 2008 2012 2016 YEAR □ MAX + MIN X MEAN(C)EC(mmho / c m ) MAXIMUM MINIMUM EC VALUES FOR WELL—48 1980 1934 1983 1992 1996 2000 2004 2008 2012 2016 YEAR □ MAX + MIN X MEAN(C)(uj0/oqujuj)33 MAXIMUM & MINIMUM EC VALUES YEAR □ MAX + MIN X MEAN(C)( LU D/O q ULJUJ ) Q3 MAXIMUM & MINIMUM EC VALUES FOR WELL—50 1980 1934 1988 1992 1996 2000 20G4 2003 YEAR 2012 f_. 2016 O MAX + MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES MAX YEAR + MIN X MEAN(C)EC(mmho/crri) MAXIMUM & MINIMUM EC VALUES 16 □ MAX YEAR MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES 12 □ MAX YEAR MIN X MEAN(C)1« < ■ L MAXIMUM & MINIMUM! EC VALUES YEAR + x MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES YEAR □ MAX + MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES YEAR □ MAX + MIN X MEAN(C)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES 15 YEAR □ MAX + MIN X MEAN(C)(UJ 0/0 L|UJLU )03 MAXIMUM & MINIMUM EC VALUES 15 □ MAX YEAR MIN X MEAN(C)(tuo/oqujijj)03 MAXIMUM & MINIMUM EC VALUES 9 YEAREC(mmho/cm) MAXIMUM & MINIMUM EC VALUES FOR WELL—64 15 1980 1984 1988 1992 1996 2000 2004 2008 2012 2016 YEAR □ MAX + MIN X MEAN(C)(Luo/oqujLU)33 MAXIMUM & MINIMUM EC VALUES 11EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES YEAR □ MAX + MIN x MEAN(C)EC(mmho/crn) MAXIMUM & MINIMUM EC VALUES 13 YEAR D MAX 7 B jHM' + MIN X MEAN(C) (|JQ QS 0^9 R9S BBBiEC(mmho/cm) 12 □ MAX YEAR MIN X MEAN(G)EC(mmho/cm) MAXIMUM & MINIMUM EC VALUES MAX YEAR + MIN X MEAN(C)(LU D/OL| LUUJ ) 93 MAXIMUM & MINIMUM EC VALUES 17 □ MAX YEAR MIN X MEAN(C)figuresII I .• IV LG ETo GhmI RoodM M ■ I MFigure 4 PIEZOMETRIC CROSS SECTIONS. - MELKASADI AREA SECTION B-B GROUNO SURFACE PIEZOMETRIC SURFACE |AUG.MV$| PIEZOMETRIC SURFACE Ifej IMAI AS PER HALCROW fpd — Flood protection ovkc River Bed level SECTION C-E1LZDMETRIC .CROSS - SECTIONS AM1BARA-AREA Figure 5--------- AJ* « C s.-N ■I in LHJ U lS00*1 -t PREDICTEO GROUNDWATER DEPTH CONTOUR MAP FOR YEAR 2016 9. . ■1 »i M**/ N u«n»M «UM I |A«Tt <n II II II p [I [I n n D D I II I I I I I IM tIu iIi kt hi hl hl hi hi hi <h
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