Abstract: The major objectives of the project is to assess lithology of bore wells, impact of canal irrigation water on ground water regimes, water quality of return flow and bore well/plezameters wells and assessment of crop water demand and supply during crop season. The lithological data of 27 bore well/piezometer showed that top layer up to 10 m depth is brown to light brown in colour and crystalline in texture. Beyond this depth it is highly weathered rock, hard rocks and granite and the colour is grey to deep grey. Such type of features resulted in to very low water discharge rate i.e 0.16 to 1.62 l/sec within 35 to 45 m bore well depth. On an average of 27 bore wells, pH of bore well water was 8.25 in pre-monsoon and 8.30 in post monsoon period. Overall the quality of irrigation water was good and was suitable for irrigation as well as domestic use. The concentration of total alkalinity, hardness, calcium, magnesium increased in post monsoon period over pre-monsoon period but reverse was the trend with carbonate concentration. High and positive correlation of pH with carbonate was found. Correlation coefficient of total hardness with calcium, magnesium, chloride was positive and highly significant. Similarly very high correlation of alkalinity with calcium and magnesium indicated higher concentration of its carbonate and bicarbonate salts in ground water.
Introduction
The present scenario on growth rate of food production is not sufficient to feed the increasing population in near future. For increasing food production from the existing cultivated area, it is possible only through irrigated agriculture. For this purpose, more area under irrigation is to be brought through surface and ground water. In arid and semi arid region irrigation facilities are created by constructing irrigation projects and sufficient amount of irrigation water is supplied to the crops in irrigation command. But irrigated agriculture in such region contribute heavy salts as well as nitrate (in region of heavy fertilizer application) in ground water and irrigation return flow. Subsequently the man made created bad quality water limits industrial, urban and agriculture use. To avoid any adverse effect of bad quality ground water on human health, European and USA have fixed certain norms and the upper limit for salt and nitrate is 2.8 dS m-1 and 50 mg L-1, respectively for EU (European Union, 1998) and 45 mg L-1 for nitrate in USA (Tanji and Hanson, 1990). In Western San Joaquin valley of California in USA, Tarbonton et al. (2005) worked on salinity appraisal in 89,400 ha area and found that 38% irrigated area is affected due to waterlogging and about 0.5 to 3.3 million ton of salt is accumulated in soil due to evaporation, shallow ground water and semiconfined aquifer. In arid irrigated agriculture, return flow salt loading values ranges from 2 to 20 Mg ha-1/year (Aragues and Tanji, 2003).
In India about 45% of the total aquifers exploited for irrigation have a water of poor quality. For using such type of ground water for irrigation its suitability is also very important as the water quality depends upon hydro geological environment. In arid and semi-arid region and in coastal region ground water quality is generally not suitable for irrigation due to more salt loads. Still in such areas (Punjab, Haryana and other part of Rajstahan) farmers are using tube well as well as canal water through proper proportion. In Indira Gandhi Nahar Pariyojna (northern region of India) about 7.33% of the canal command area have come in the grip of water logging and soil salinity. In other irrigation command areas (Mula and Jayakwadi in Maharashtra, Chambal and Tawa in Madhya Pradesh, Krishna, Godawari and Nagarjunasagar in Andra Pradesh and Ghatprabha in Karnataka),located in semi-arid region have developed into waterlogged and salt affected soils (Singh, 1996). Hence frequent chemical analysis of ground water and canal water for irrigation is very important for future strategy.
In state of Orissa (Eastern region of India),ground water development is quite low (14.8%) due to receipt of good amount rainfall during wet season (86% of the total annual rainfall of 1503 mm) and low cropping intensity (140%). The quality of groundwater in all part of Orissa is quite satisfactory except in coastal alluvial tract, it is saline. In coastal area of the state, shallow groundwater table is suitable for irrigation but exhaustive exploitation may cause intrusion of bad quality sea water. In western part of Orissa particularly in drouhght-hit districts (Koraput, Bolangir and Bargarh), annual rainfall is comparatively less than the coastal districts and major portion of the aquifer is confined to hard rock which influences quality of ground water and its suitability for domestic, agriculture and industrial use.
In the present investigation, 27 borewells /piezometers were installed during March 2000 in Chaukinala watershed (in western Orissa) in tail end of Baragarh distributaries of Hirakud Irrigation Command. The excess water through surface and sub-surface is going into the Chaukinala i.e., drainage outlets and water quality of borewells/piezometers, canal water and irrigation return flow is monitored to evaluate any changes in water quality parameters. The major objectives of the project is to assess lithology of bore wells, impact of canal irrigation water on ground water regimes, water quality of return flow and bore well/piezometer wells and assessment of crop water demand and supply during crop season.
Materials and Methods
Project Site and Water Quality Analysis
The project was undertaken in Chaukinala watershed (lat. 20°55’
to 21°5’ and long. 83°4’ to 83°50’), a tail end of
Baragarh canal system which take off from Hirakud Dam. The canals, Berkerly
distributory, Bhimtekra distributory form the catchment boundary of the Chaukinala-a
small stream that drains surface runoff during rainy season and part of irrigation
return flow to the Mahanadi river. The Mahanadi river also forms a boundary
of the study area (Fig. 1). The Bhimtekra distributory with
about 25.5 km length and Berkerly distributory system with about 31.0 km length
canal system form the study project. The total geographical project area is
28502 ha. The project was started in March 2000 after delineating study area
and by installing 27 piezameters/bore wells to a depth of 35 to 45 m. While
installing bore well, soil samples from different layers were collected and
have analyzed for its various lithological characters. After installation, groundwater
from 27 piezameters,irrigation return flow and canal water were collected during
pre rainy season ( 8 to 11 June, 2000) and post rainy season (19 to 24 Novermber,
2000). These samples have been analyzed for pH,TDS, alkalinity, hardness, calcium,
magnesium, carbonate, bicarbonate, chlorides during pre and post rainy season.
The water pH was measured with digital pH meter. Chloride was estimated by argentiometric
method in the form of silver chloride. Total dissolved solid (TDS) was estimated
by gravimetric method, alkalinity was determined by volumetric method using
sulphuric acid as titrant and pheno-phthalein and methyl orange as indicators.
| Fig. 1: | Chaukinala watershed of Hirakud irrigation project |
Total hardness and calcium was determined by EDTA titrimetric method while magnesium was calculated by deducting calcium from total hardness. The correlation coefficient among different variables have been estimated with standard statistical packages and the correlation coefficients having highly significant ( r>0.8 ) have been regressed with pair of variables to make easy assessment of other variables which are not estimated due to lack of facilities with the institutions and the predicted other quality parameters are available within desirable level of precision or not.
Results and Discussion
Lithological Observation
Table 1 revealed that in most of the locations top soils
are brown to light brown in colour except in six locations viz., Kulparaha,
Barpadar, Mohadavpali, Urle, Sankara, Sasamura, it is light black in color.
Below layers are highly weathered rocks and weathered granites. At 35 and 45
m soil depth most of the places has hard rock and hard granites.
| Table 1: | Lithological information of borewells under Chaukinala Watershed |
These types of rocks are not water bearing strata. Hydrogeology of the district Bolangir have been studied in details by many worker (Basak, 1977; Kar, 1997) and found that major part of the districts are occupied by hard and compact crystalline rocks which lacks porosity. Such type of lithological features of aquifer up to 45 m soil depth results into frequent fluctuatiion of water level during rainy season and then sudden drop after monsoon season. Further, Central Ground Water Board, South Eastern Region, Bhubaneswar, Orissa prepared a comprehensive report on conjuctive use of surface and ground water resources in Hirakud irrigation project during 1998 and made certain remark that in total CCA of 1.57 lakh ha area of Hirakud command with irrigation intensity of 170% ( 100% in kharif and 70% in rabi), granite and granite gneisses are the major rocks occupying more than 90% of the total geographical area of the command. These rocks are generally hard and are devoid of porosity.
Depending upon the texture, structure and porosity of the weathered rocks, the water yielding capacity of the bore differed. The data on discharge rate of 27 bore wells which were installed during 10 to 27 March 2000 in soil depth of 35 to 45 m varied from 0.38 l/sec to 1.63 l/sec which is quite low (Table 2). This low water yielding capacity of the bore well is not acceptable by Government of Orissa and NABARD for funding to the farmers for installing shallow tube wells as minimum discharge rate for awarding loan should be 2.0 l/sec. Central Ground Water Board, Bhubaneswar (Anonyumous, 1998) has made 28 exploratory and 4 observation wells up to 200 m depth in whole Hirakud command and observed that the discharge rate of these wells are ranging from 0.88 to 4 l/sec. In some of the undulating granite terrains bore well made up to 100 m depth yielded 5 l/sec which is quite useful for ground water development. In the irrigation command particularly the tail reach farmers are not getting sufficient amount of canal water in proper time like head reach farmers. So, exploiting ground water through deep tube well is highly essential for which attention for immediate implementation of the ground water development project is required.
Water Quality of Project Area
The quality of ground water depends upon the nature of geological formation.
physiographic features and climatic conditions of the area. The quality of the
water sample collected from 27 bore wells during pre monsoon season of June
2000, showed that the ground water is neutral to alkaline in reaction and the
pH varied from 7.0 to 9.0 with standard deviation of 0.351 (Table
3).
| Table 2: | Details of observation bore wells in Chaukinala water shed installed during March 2000 |
| Mean = 0.78 l/sec | |
| Table 3: | Hydrochemical data of ground water, canal water and irrigation return flow during 6-10 June 2000 |
| Figures in bracket are values of November 19-24, 2000. In November 2000,TDS, Bicarbonate and chlorides were not analyzed | |
Out of 27 bore wells water of 20 bore wells had pH more than 8.0 and rest had pH between 7.0 and 7.9. In the post monsoon period i.e in the month of November, 2000 there was no change of ground water pH however the pH of canal water irrigation return flow was slightly higher i.e 7.4 and 9.0, respectively as compared to the values recorded in June 2000. In later case, seepage and subsurface flow of canal water has higher pH due to dissolved chemical constituents, flowing in the drainage nala. In case of total dissolved solids, in 14 bore wells the values were in safe limit for domestic use and it ranged from 258.0 to 487.5 mg L-1 but in remaining 13 bore wells the TDS value was ranging from 518.0 to 869.5 mg L-1 which exceeded the permissible limit of 500 mg L-1 (World Health Organisation). The higher value of TDS in these bore wells could be due to higher mineralization rate of the minerals available in aquifers. Total hardness as CaCO3 of the water sample were also quite low during pre monsoon period and ranged between 40-189 mg L-1 which were quite safe for domestic use but in November 2000 total hardness as CaCO3 increased to 60-328 mg L-1 in two bore wells the total hardness as CaCO3 was greater than 300 mg L-1 which exceeded the permissible limit for consumption. Calcium concentration in water during pre monsoon was quite safe under permissible limit of 75 mg L-1. However in post monsoon period, calcium concentration was above 75 mg L-1 in four bore wells with maximum of 90 mg L-1. With regard to magnesium concentration, in one of the bore well it was 36.48 mg L-1 during pre monsoon and in two bore wells it was 36.48 to 36.80 mg L-1 during post monsoon period which can not be used for drinking purpose as it exceeded the permissible limit of 30 mg L-1. In canal water magnesium concentration was 4.8 to 8.64 mg L-1 but in irrigation return flow it was as high as 10.56 mg L-1. Higher amount of magnesium in irrigation return flow might be due to movement of magnesium salt available in the soil profile along with seepage and subsurface flow.
Carbonate in groundwater during pre monsoon period was present in 18 locations with concentration ranging from 9.6 to 38.4 mg L-1 and in rest seven locations it was nil but during post monsoon period, carbonate was available in 16 locations with values ranging from 19.6 to 24.0 mg L-1. In canal and irrigation return flow it was 9.6 and 14.4 mg L-1, respectively. Bicarbonate was available at the tune of 87.84 to 375.76 mg L-1. During post monsoon period bicarbonate concentration generally increases as microbial organism produces CO2 in the process of respiration. But in pre monsoon season roots activities and microbial activities are slightly ceases due to non availability of adequate soil moisture in profile and decaying of roots. During post monsoon period, the bicarbonate and chlorides was not estimated. Chloride concentration during post monsoon period was recorded to be 11.34 to 113.44 mg L-1. The concentration of different salts in ground water of this region is not harmful to the crops if the ground water is made available to the farmer in un-command area. Central Ground Water Board, Bhubaneswar (Anonymous, 1998) collected water sample from 17 deep bore wells having total depth from 100.5 to 200 m and found that SAR value is ranging from 0.9 to 2.2 m mole L-1)1/2. In shallow bore wells the SAR value was in the range of 0.68 to 4.05 m mole L-1) 1/2 and majority of water sample (56.25%) were in the category of C2S1 as per USSL classification which can be considered as good quality water. Chowdary et al. (2005) studied ground water quality of Godavari Delta Central Canal Irrigation Project in East Godavari district of Andhra Pradesh, India in total command area of 84, 000 ha. Rice is main crop grown during rainy season and it is fertilized with 120 kg N ha-1. They monitored nitrate nitrogen in ground water and the concentration was recorded to the tune of 20-50 ppm which may further increase if rice is grown continuously. They suggested to take alternate crop in this command area. Similar results have been reported by Ozha et al. (1993) and Vijay Kumar et al. (1993) in different irrigation command in India where rice has been intensively cultivated during both rainy and winter season. In Philippines (at Magnuang, Bata, Ilocos Norte) Gumtang et al. (1999) assessed ground water dynamics and water quality during October, 1994 to March, 1996 (wet and dry season) in 19 selected wells of 265 ha area. They found that in all observation wells electrical conductivity (700-3000 microhos cm-1) and HCO3- (90-500 ppm) exceeded FAO threshold quality of irrigation water. Electrical conductivity(EC) increased at the start of wet season and lower concentration was observed in wet season due to dilution effect. However the level of Cl – and pH were in safe limit except in one open well. With regards to NO3-N, eight wells showed near or above the World Health Organisation NO3-N limits(10 ppm) for drinking water. This was due to application of high amount of nitrogenous fertiliser (120 kg N ha-1 ) in rice during wet season and 340 kg N ha-1 during dry season in other upland crops.
The correlation coefficient of pH with TDS, alkalinity, hardness and bicarbonate was significant (Table 4), however the relationship between pH and carbonate was highly significant (r = 0.80).
| Table 4: | Correlation coefficients between different hydrochemical parameters |
| Figures in parenthesis are values of NOV. 2000 | |
| Table 5: | Regression equation for various hydrochemical parameters (June 2000) |
| Table t at 25 and 26 degree of freedom at 5% level of significance is 2.060 and 2.056, respectively Figure in brackets are standard error | |
| Table 6: | Regression of highly significant (r =>0.80) hydrochemical parameters June 2000 |
| Figure in parentheses are standard error | |
Total dissolved solids with total alkalinity and bicarbonate was strongly and positively correlated. Total alkalinity of ground water was dominated with carbonate and bicarbonate of calcium, however it was not strongly correlated with hardness, calcium and carbonate. Total hardness was stroungly and positively correlated with mangesium and chlorides, which indicated higher concentration of these salts. In ground water calcium chloride and calcium carbonate salts is present in adequate quantity and highly correlated with total hardness. Jain and Sharma (2002) have developed systematic correlation of ground water sample of Malprabha basin and found that electrical conductivity (EC) and total alkalinity, total hardness, chloride, sulphate, nitrate, sodium, calcium and magnesium is highly correlated.
Considering pH as independent variable and all other parameters as dependent variables to evaluate water quality parameters if only pH of water is estimated since in all locations estimation of all water quality parameters at the site is not possible due to several constraints and then developed the regression equation. The results presented in Table 5 and 6 show that in pre monsoon period an approximate prediction of carbonate in ground water through observed water pH is possible to some extent as the coefficient of determination is higher and the ’ t ‘ ratio is also significant, but for rest of parameters prediction through water pH is not acceptable in this selected site. However, Krishna et al. (1995); Singanan et al. (1995) Balasankar and Nagrajan (2000) have widely used the regression equation for estimating concentration of several ground water quality parameters.