ASSESSMENT OF SURFACE WATER RESOURCES FOR IRRIGATION PURPOSES IN ASSIUT GOVERNORATE, UPPER EGYPT

Water from some sources may contain so much salt that it is unsuitable for irrigation because of potential danger to the soil or crops. Irrigation water quality can best be determined by chemical laboratory analysis. The main objectives of this study are to assess the surface water quality for irrigation, and to present solutions for managing and protecting these resources in Assiut area. To achieve that, thirty surface water samples were collected from River Nile and main irrigation canals. Chemical analysis was carried out and analyzed for major and trace elements according to the irrigation water guidelines of (FAO 1985), and (Rowe, et al. 1995), taking into account the spatial variations and the representation of the hydro chemical data. The results show that 97% of surface water samples lie within no restriction on use level and 3% is represent slight to moderate restoration on use according to TDS concentrations. 97 % of surface water samples belongs to (C2-S1) good water for irrigation all crops in all soils and 3 % belongs to (C3 -S1) good water for irrigation all crops in all soils under ordinary and specific condition like adequate drainage and leaching According U.S. salinity laboratory staff classification depend on (EC, TDS and SAR). Where 87% Excellent water for irrigation sensitive all crops and low likelihood of soil problems According Boron content. Consequently, it is recommended to prevent the sewage and domestic waste water, and the industrial waste water from direct disposal without treatment to the irrigation canals and River Nile; controlling the use of fertilizers and pesticides in the agriculture purposes; selected the suitable crops for every sector (area) according to the chemical characters of the available irrigation water and soil properties.


Ibrahimia Canal (First Level Canales)
Downstream of the Aswan dam, there are seven barrages to increase the river water level so that it can flow into first level irrigation canals. One of them is the Ibrahimia canal (with length 350 km), completed in 1873, the largest artificial canal in the world. It branches off the left bank of the Nile in Assiut figure 3 (a,b), Figure 3: (a,b) show the outlet of the Ibrahimia canal at Assiut city from River Nile Whose water level is 50 m above the sea level, and then runs parallel to the River Nile. Its discharge is increased by the Assiut Barrage completed in 1903. It extend toward the north direction parallel to the river Nile with distance about 55 km through Assiut governorate figure (1).

Nagi Hamadi El-Sharqia Canal; (First Level Canals)
Get its water from River Nile at Naga Hamadi Town, at the upstream portion of the old Naga Hamadi barrage where the water level fluctuated between 66.5 to 69 m above the sea level, and extend toward the north direction parallel to the River Nile, in East portion of Qena and Sohag governorates and inter Assiut governorate (East River Nile) at El-Badari Markaz until riche south El-fathe Markaz figure (4).

Nagi Hamadi El-Gharbia Canal; (First Level Canales)
Get its water from River Nile at Naga Hamadi Town, at the upstream portion of the old Naga Hamadi barrage where the water level fluctuated between 66.5 to 69 m above the sea level, and extend toward the north direction parallel to the River Nile, in East portion of Qena and Sohag governorates and inter Assiut governorate (East River Nile) at El-Ghanaim Markaz until riche south Assiut Markaz figure (4). The canals of the irrigation system runfrom south to north nearly parallel to each other as well as to the River Nile.

Drainage Channels
Drainage channels and drainage through subsurface drains below fields is essential to prevent a deterioration of crop yields from soil salinization. The main drain canal in As suit governorate is EL-Zenar drain, extend toward the west and south west of Assiut city and Markaz as showing in figure (2-b) at the western portion of the River Nile. it receive the most of the waste water (agriculture , domestic and sewage …ets) from second and third level drain canals which distribution all over the west middle portion of Assiut governorate and from drainage through subsurface drains below fields (direct or indirect) , than discharge into the River Nile at Assiut town (downstream portion of Assiut barrage ) figure (2-b).
Surface water system represented the main of recharging source of the groundwater (Quaternary Aquifer) beside seepage from excess irrigation water.

Climate
The study area is characterized by arid to semiarid, hot climate.

Materials and Methods
To evaluate the surface water resources in Assiut Governorate for irrigation purposes, the total of 30 surface water samples were collected from irrigated surface water, respectively (Figure 2-b). We used the GPS instrument ( Figure 5-a) to locate the studied sites where the water samples were collected. The water analyses were carried out, according to the methods adopted by Rainwater and Thatcher (1950) and those described by Fishman and Friedman (1985), in the Geology Department, Faculty of Science, Minia University, and the Agency of Environmental Affairs of Assiut Governorate. The pH, electrical conductivity, and temperature are measured in situ using Ultra meter tm 6p ( Figure 5-b). The Cl, HCO3, Ca, and Mg elements were measured by titration, while SO4 was estimated by turbidity, and the Na and K elements were defined by the flame photometer. The samples were acidified with ultrapure nitric acid, after filtration, to avoid complication and adsorption. The acidification was accomplished in situ and in case of toxic metals determination. Then the samples were transported to the laboratory and stored in a refrigerator at approximately 20 0C to prevent change in volume due to evaporation. The toxic metals (As, Ba, Cd, Cr, Cu, Pb, Ni, Mn, Fe, NO2, and NH4) were determined by the ICP (Inductive Couples Plasma)-AES (Optima 3000; Perkin Elmer). The analyses were carried out at the Agency of Environmental Affairs in Assiut Governorate. The results of laboratory and field measurements were within the limit of 10%, and therefore a significant alteration of the alkalinity during storage and transport can be excluded.

Results and Discussion
Soil scientists use common categories to describe the irrigation water effect on crop production and soil quality (e.g. salinity hazard, sodium hazard, chloride, boron, nitrate, PH and total alkalinity). The other potential irrigation water contaminants that might affect the suitability of agricultural use are heavy metals and microbial contaminants. Quality standards for irrigation water are based on important factors that affect the productivity of the crops. Several authors have proposed many different classifications for irrigation water. Considering the quality of water and their suitability for irrigation purposes, a number of concepts must be taken into consideration; these are: 1) The total concentration of soluble salt (TDS).
2) The relative proportion of sodium to other cataions (SAR).
It is notable that the quality requirements of irrigation water vary between crops types and drain ability of soils and climate.
The recommended water quality criteria for irrigation (according to FAO, 1985FAO, , 2010) and the guidelines for interpretation of water quality for irrigation (according to Ayers, 1977;Ayers and Wesrcot,1985, Eaton,1950, leeden et al. 1990 are presented in Tables 3,4         The application of these standards to the chemical data in the studied area tables (1) revealed the following results:

Salinity and Total Dissolved Solids
Electrical conductivity (EC) and salinity usually contribute to the total dissolved solids (TDS). The problem occurs when the salts accumulate in the root level in an extent preventing the crop to be able to extract sufficient water from the salty soil solution, causing a water stress for a significant period. If water uptake is appreciably reduced, the plant slows its rate of growth. The most influential water quality guideline on crop productivity is the water salinity hazard that is measured by electrical conductivity (ECw). The primary effect of the high ECw on crop productivity is the inability of the plant to compete with ions in the soil solution for water. The higher the ECw, the lower the level of water content available to plants; even though the soil may appear wet (Yours et al., 2009). For surface water samples, the TDS values range from 170 to 578 mg/l within the range of Low Likelihood of soil problems, except at sites number 10 and 29 where TDS values are medium likelihood of soil problems ( Figure 6).

Sodium Ions
Sodium toxicity is often reduced if sufficient calcium is available in the soil. Excessive sodium causes mineral particles of soil to disperse and water penetration to decrease. High sodium concentration accompanied by decrease in the infiltration rate causes problem as the crop could not be adequately supplied with water especially when the hydraulic conductivity of the soil profile is too low to provide adequate drainage. If calcium and magnesium are the predominant adsorbed cations on the soil exchange complex, the soil tends to be easily tilled and have a readily permeable granular structure (Yousry, et al., 2009).
the sodium concentration in surface water samples (Figure 7), ranges between 12 mg/l (0.544 meq/l) to 34.5 mg /l (1.56 meq/l) indicating that there is no restriction of using sensitive crops (Ayers and Westcot, 1985), and lies within the low likelihood of soil problem according to FAO (1985).It is notable that sodium is toxic to certain plants and causes an adverse effect on the soil structure, infiltration, and permeability characteristics (El-Sherbini et al., 1997).

Infiltration Concerns
Calcium, magnesium, and sodium are used to calculate the sodium adsorption ratio (SAR) of the irrigation water. The adjusted SAR is calculated using information from (Suarez 1981), which includes the bicarbonate content of the irrigation water. The permeability hazard of an irrigation water sample is related to both the SAR and EC of the irrigation water (Flynnl, 2009).
An infiltration problem occurs if the irrigation water does not enter the soil rapid enough during a normal irrigation cycle to replenish the soil with water needed by the crop before the next irrigation. Low salinity water (less than 0.5 ds/m and especially below 0.2 ds/m) is corrosive and tends to leach surface soils free of soluble minerals and salts, especially calcium, reducing their strong stabilizing influence on soil aggregates and soil structure without salts and without calcium. The soil disperses and the dispersed finer soil particles fill many of the smaller pore spaces, sealing the surface and greatly reducing the rate at which water infiltrates the soil surface. We herein used the method of (Richards 1954) to evaluate the infiltration potential (e.g. the sodium adsorption ratio; SAR).

Sodium Adsorption Ratio (SAR)
The sodium adsorption ratio (SAR) is used to estimate the sodality hazard of the Water. SAR is a measure of the tendency of the irrigation water to the soil clay minerals with sodium ions, sodium clays have poor structure and develop permeability problems (George, 1983). SAR is defined as in equation Where Na + , Ca2 + and Mg2 + represent meq 1 -1 of sodium, calcium and magnesium ions, respectively. SAR values were evaluated according to FAO guidelines.
According to the U.S. salinity staff classification (Richards 1954) which based on the sodium adsorption ratio (SAR) and the specific conductance (in micro mhos) the water divided into four classes (table 9). Is not suitable for irrigation under ordinary conditions but may be used occasionally under special conditions as the soils must be permeable, and Drainge must be adequate, irrigation water must be applied in excess to provide considerable leaching. SAR quality Range Usage S1 Low sodium water 0 -10 Can be used for irrigation of almost all soils with little changes of the development of harmful levels of exchangeable sodium. S2 Medium sodium water 10 -18 Will represents an appreciable sodium hazard in fine-textured soils having high cation exchange capacity, especially under low leaching conditions, unless gypsum is present in the soil. S3 High sodium water

-26
May produce harmful levels of exchangeable sodium in most soils and will require special soil management, good Drainage, high leaching and organic matter condition. S4 Very High sodium water

-100
Is generally unsatisfactory for irrigation purposes except at low and perhaps land perhaps medium salinities.
For surface water samples (Figure 8), the SAR values range from 0.81 to 1.78; indicating good (suitable) for irrigation in all soils as they are located in class [C2-S1] except at site no. 29 ( at mixed with sewage from sewage treatment to El-Zenar drain) located in class [C3-S1], the water such classes are good (suitable) under ordinary condition but it can be used under specific condition like adequate drainage and leaching (Ayers and westcot, 1985;FAO, 1985).

Residual Sodium Carbonates (Eaton's Classification, 1950)
When the sum of carbonate and bicarbonate is in excess of calcium and magnesium, there is an almost complete precipitation of the latter (Eaton's 1950). This can cause an increase in the proportionate amount of sodium, and so the effect on the soil is the high sodium content. The term residual sodium carbonates (RSC) is defined as follows: The RSC is used to distinguish between the different water classes for irrigation purposes, because the high concentration of bicarbonate leads to an increase in the PH value, which causes the dissolution of the organic matter. Moreover, the high concentration of the bicarbonate ions in the irrigation water leads to its toxicity and affects the mineral nutrition of plants (see Eaton's classification, 1950).
All the collected surface water samples have RSC values less than 1.25 epm; ranging from -2.535 to 0.4. They belong to the possibly safe water for irrigation as they are free from residual sodium carbonate (RSC) hazard ( Figure 9).

Specific Ion Toxicity
The specific ion toxicity (like chloride and boron) occurs when the decline of crop growth is due to the excessive concentrations of that specific ion rather than to the osmotic effect alone (Yousry, et al., 2009).

Chloride
For surface water samples (Figure 10), chloride ions concentration ranges between 2 mg/l (0.056 meq/l) and 75.5 mg/l (2.13 meq/l) ( Table 3). Comparing the data of chloride with FAO guidelines, it was found that all values are less than 4 meq/l. this means, there is no restriction on using it for some susceptible crops. An excess of chloride was detected at the downstream of drains. It is taken as an index of sewage pollution, where sewage water and industrial effluents are rich in chloride, and hence the discharge of these wastes results in high chloride levels in fresh waters (Ravindra et al., 2003).
Most rivers and lakes have chloride concentration lesser than 50 mg/l; therefore, the increase of this value might be an indicative to sewage pollution (Twort et al., 1994).

Boron
The boron is another element that is essential in low amount for plant growth, but it is toxic at higher concentrations. In fact, toxicity can occur on sensitive crops at concentrations lesser than 1 mg/l. surface water rarely contain enough boron to be toxic but groundwater occasionally contains toxic amounts. Boron toxicity symptoms normally sow first an older leaf as a yellowing, spotting, or drying of leaf tissue at the tips and edges (Yousry, et al., 2009). While According to (FAO, 1985(FAO, & 2010 guidelines for irrigation water, depended on boron content and likelihood of soil problems can be classified surface and groundwater in study area as the following manner: all samples from River Nile and main irrigation canals have B2 + values less than 0.7 mg/l. (ranged from 0.023 to 0.35 mg/l) They belong to low likelihood of soil problems (none degree of restriction on use) for irrigation (the possibly safe water). While samples from El-Zenar drain have B2+ values more than 0.7 mg/l and less than 3 mg/l.(ranged from 1.1 to 1.5 mg/l) They belong to medium likelihood of soil problems (Slight to moderate degree of restriction on use) for irrigation ( Figure 12).

Bicarbonates
The presence of bicarbonate leads to the precipitation of calcium carbonate (scale) at water pH greater than 7.5. Acidification of the water is the best way to manage bicarbonate, where water levels lesser than 1.5 mg/l will not cause problems. Severe problems can be noticed at levels above 2.5 mg/l. For surface water samples (figure 13), the bicarbonate ions concentration ranges from 45 mg/l to 201.2 mg/l (0.74 to 3.3mg/l), when compared to FAO 1985 guidelines we find that all the surface water samples are considered as belonging to the slightly to moderate restriction on use (medium likelihood of soil problem), except at site no. 18, which shows little problem.

Heavy Metals
Not all trace elements are toxic and many of them are essential for plant growth, but in small quantities (e.g. Fe, Mn, Zn). However, excessive quantities will cause undesirable accumulations in the plant tissues and reduces the growth rate. By comparing the result with the recommended maximum concentrations of some trace elements in irrigation water (FAO, 1985) and (Rowe et al., 1995) were 5, 5, 2, 0.2, 0.2, 0.2, 0.1, 0.1, 0.05 and 0.01 the maximum limit for lead, iron, zinc, copper, nickel, manganese, arsenic, chromium, cobalt and cadmium, respectively can be obtained the following:.
For surface water, comparing the above recommended values with the data obtained from the analysis of heavy metals revealed that lead, , zinc, copper, arsenic, and chromium values are within the limits recommended by FAO (1985), and ( Rowe et al., 1995) (e.g. none restriction on use). However, the manganese concentration is high at sites no. 26, 27, the cadmium concentration is high at site no 26, the nickel concentration is high at site no. 15, and the iron concentration is high within about 32% of the studied sites, and therefore lies within the slightlymedium to severe restriction on use.
The Iron concentration ranges between 0.0011 and 3.5 mg/l, the manganese concentration ranges between zero and 0.7mg/l, the copper concentration ranges between zero and 1.85mg/l, the recorded cadmium concentration ranges between zero and 0.03 mg/l, the chromium concentration ranges between 0.0004 and 0.04 mg/l, the Lead concentration ranges between zero and 0.1 mg/l, the nickel concentration ranges between 0.0065 and 0.25 mg/l, the zinc concentration ranges between 0.003 and 1.7 mg/l, and the recorded arsenic concentration is less than 0.1 mg/l in all sites ( figure 14).

Miscellaneous Elements
The miscellaneous elements include the pH values, the total alkalinity, and the nutrients (ammonia and nitrates)

PH Values
For surface water samples, the pH values range between 6.6 and 8.9 The increase of pH values at sites no. 6,7,9,11,12,13 and 16 could be related to photosynthesis and growth of aquatic plants (Allem, et al., 1969;El-Wakeel et al.,1970). Photosynthesis consumes carbon dioxide leading to the rise of pH value.
However, chemical reactions in water that are controlled by the pH values and the biological activity is usually restricted to a fairly pH range of 5 to 8 (Tebbutt, 1998).
In general, unpolluted streams normally show a near neutral or slightly alkaline. Finally, the pH values were found to be within the permissible limits of FAO (1985) at sites no. 6, 7, 9, 11, 12, 13 and 16.
The greatest direct hazard of an abnormal pH value is its impact on the irrigation equipments. The pH value that is lesser than 6.5 will generally lead to potential corrosion of the irrigation equipments ( figure 15).

Total Alkalinity
For surface water samples, the total alkalinity ranges between 122 to 210 mg/l about (1.99 to 3.44 meq/l) Alkalinity serves as a pH reservoir for inorganic carbon. It is usually taken as an index of productive potential of water (Ravindra et al., 2003).
Alkaline water leads to high bicarbonate. The bicarbonate concentrations of surface water ranges between 0.74 and 3.29 meq/l indicating that there is a slight to moderate restriction of use; however, site no. 8 is considered as belonging to the level of no restriction of use ( figure 13).  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   The nitrate concentration within the surface water samples (Figure17) ranges from 0.006 to 14.9 mg/l (e.g. within the permissible low level of likelihood of soil problems; none restriction of use at all sites for all crops except the site no. 24, which lies within the level of the slight to moderate restriction of use).
The high concentration of ammonia in wastewater discharging from drain or sewage waste led to the high contamination of the water by ammonia. The ammonia concentration in unpolluted water is lesser than 0.2 mg/l as nitrogen (chapman, 1992). By comparing the ammonia and nitrate values with the FAO guidelines (5 mg/l N) it is found that there is no restriction on using the studied water samples for sensitive crops except above mentioned sites.

Conclusions and Recommendations
Our analyses detected the variation in the properties of both the surface and ground waters. All the PH values of surface water samples are within the recommended limits of FAO (1985), except at sites no. 6, 7, 9, 11, 12, 13, 14 and 16, which exhibit more than the recommended limits. All the TDS concentrations in surface water samples are within the recommended limits of FAO (1985) indicating none restoration on use, except at sites no. 10   Consequently, we recommend a strong control is needed concerning the use of fertilizers and pesticides in the agriculture purposes, as well as selecting the suitable kind of crops for each area as in (figures 18 and 8) which show classified the surface water in study area based on the hazard of TDS, Na, EC and SAR values and their effected on planet growth and its products in related to soil problems, also as show in details in (figures 19 and 11) and (table 8) which obtained more details based on Boron hazard in related to the sensitivity and tolerant of deferent crops to it. Preventing the direct disposal of sewage, domestic wastewater, and industrial wastewater before treatment to the irrigation canals and the River Nile. We also stress on preventing the construction of open septic tanks, especially near the pumping well. Goog (belong to the safe limits of irrigation water for sensitive crops, and excellent for semi-tolerant and tolerant crops)