الفهرس 
ACKNOWLEDGEMENTSOnly 14 pages are availabe for public view
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Abstract
The study area (Assiut Governorate) is located 300 km south Cairo
between 26° 20ʹ 00ʹʹ to 27° 40ʹ 00ʹʹ N latitude and 30° 30ʹ 00ʹʹ to 31° 40ʹ
00ʹʹ E longitude. The limestone plateau in Assiut region is a part of the major
Eocene plateau that covers major parts of the western and the eastern desert of
Egypt. During the last seven years, some investors started digging groundwater
wells and cultivating some soils, of this plateau while some others just put their
hands on the land as a sort of confirming positioning. So, the physical
properties and water resources of these soils have been unknown.
This study is an important step to investigate the physical properties, and
water resources of these soils for agricultural use and their favorable
management practices on the short and long terms.
Therefore, the main objectives of this work were:
1. To assess some physical and hydrological properties as well as their
interrelation of the studied soils.
2. To recognize the groundwater quality for irrigation purposes and
initiates its contour map.
So, four transect was chosen to represent various parts of the eastern and
western limestone plateaus at Assiut, Egypt. The sites of each transect were
carefully selected by GPS to represent most of the various soils; the average
distance between each two consecutive soil profiles was about 5-8 km, with a
total number of 40 profiles, number of 119 soil samples and a total number of
15 groundwater samples. Disturbed and undisturbed soil cores were collected
from the profile layers, according to vertical morphological variations.
Soil physical, hydraulic and chemical properties were measured and
determined. Chemical properties and quality parameters of the groundwater
samples were also, measured and determined. The obtained results revealed in
the following:
Soil properties:
1. The gravel content ranges from 1.18 to 73.43 % by weight. The highest
amount of gravels occurs in the subsurface layer of most soil profiles. Soil
texture is mostly coarse (mainly sand, loamy sand and sandy loam). Finer
soil texture i.e. loam, and sandy clay loam is not frequently present.
2. The bulk density varies from 1.21 to 1.97 Mg/m3. A slight increase in the
bulk density was observed with depth. This may be related to a high
content of the sand fraction and to their lower contents of silt, clay and
organic matter. Non-significant variations in bulk density values were
found among soil samples.
3. Most of the studied soil samples have higher particle density (Dp) values
than 2.60 Mg/m3. Non-significant variations were recorded in particle
density values.
4. The studied soil moisture characteristics cure moisture content indicated a
marked decrease of soil moisture content (50%) when the soils were
subjected to suction above one atmosphere. Moisture content all transect
profiles at all pressure heads has medium values of C.V. The obtained
results indicated that soil texture and CaCO3 content have a major
influence on the variations of water retained under different suction
levels.
5. The studied saturated soil hydraulic conductivity indicated that soils can
be categorized between low to excessive permeability. The C.V % for
saturated hydraulic conductivity (Ks) was very high and ranges from 124
to 217.2%. These high variations may be attributed to the variability of
soil deposition, pedogenic and hydrologic processes. The obtained results
of Ks indicated that soil texture and CaCO3 content have a major
influence on the variations of saturated hydraulic conductivity.
6. The unsaturated soil hydraulic properties, K (Ɵ) decreases greatly with
decreasing soil moisture content. Also, the K (Ɵ) decreases nonsignificantly
with increasing of total CaCO3 % content. The unsaturated
hydraulic conductivity K (Ɵ) of the transect profiles have very high
values of C.V. The K (Ɵ) DROP drastically from 0.1 atm. (suction) up to
0.33 atm., afterward, the curve starts to flatten with a minimum rate of
change with increasing the suction head.
7. The soils have a high content of calcium carbonate ranging between 13.10
and 93.80%, with a coefficient of variation equal to 40.10% that it is
classified as highly variable. The high content of CaCO3 in these soils is
mainly attributed to the pedogenic carbonate formed from limestone
parent material. Most of the soil profiles are classified as extremely
calcareous in terms of CaCO3 content according to FAO (2006).
8. The organic matter content of the soil samples ranges between 0.03 and
0.83%. In most soil profiles, organic matter decreases with depth. This
reflects the little effect of rainfall during winter and the prevailing dry
climate.
9. The soil pH values range between7.5 to 9.4. In general, the results show
relatively strong alkaline pH values for most studied samples. These soils
are classified to have low variability with respect to pH values.
10. The salinity value (ECe) of the studied samples differs between 1.7 and
109.5 dS/m. Its CV value is considered highly variable for all transects. In
general, most of these soil samples are relatively strongly saline (> 16
dS/m). This could be attributed to the barren nature of the soils and, also,
to the ineffective role of leaching due to the scanty rainfall received.
ii. Groundwater:
The groundwater quality of the limestone plateau is strongly influenced by
the water-rock interaction and anthropogenic activity. The rock dominance of
the major ion chemistry in the basin provide, an insight of chemical
weathering in the drainage basin since weathering of the different parent
rocks (e.g., carbonates, silicates, an evaporates) yields a different
combination to dissolve cations and anions to a solution.
1. The water depth in the study area varies from one place to another and is
influenced by the surface level.
The pH value of the groundwater in the study area is generally neutral and
reflecting natural groundwater (slightly alkaline) type.
3. The TDS value in the study area is considered fresh water except well no.
12 (sample 14) that is considered slightly saline according to Hem, (1970).
The TDS values of these waters are attributed to the dissolution of
limestone and to leaching of halite and gypsum deposits.
4. The EC value of groundwater samples varies between 672 and 2321 μS/m.
It fluctuates between moderate and high saline. The groundwater under
this condition can be used for irrigation if a moderate amount of leaching
occurs and crops with moderate salt tolerance can be grown in most
instances without special practices for salinity control.
5. The cation concentration in the groundwater of the study area is in the
order of Na+> Ca2+> Mg2+> K+ and that of the anions is in the order of
Cl-> HCO3
2-> SO4
2-. Cation concentrations and aonion ratio can trace
water-rock interaction processes, such as mineral weathering and cation
exchange (Han et. Al, 2009).
6. According to the Piper classifications, about 53% of the groundwater
samples are characterized by non-carbonate alkali (primary salinity) that
exceeds 50%, where the chemical properties of alkalies and strong acids
dominate properties. However about 27% of the groundwater samples are
characterized by the strong acids where (SO4+Cl) > (HCO3+CO3). They
are characterized by carbonate hardness (secondary alkalinity) that exceeds
50% and the chemical properties of the groundwater are dominated by
alkaline earths and weak acids.
7. The following, six main groups of salt assemblage:
group I : Ca(HCO3)2, MgSO4 and NaCl are noticed in samples no. 1 and
8.
group II : Ca(HCO3)2, Mg(HCO3)2, MgSO4 and NaCl are detected in
samples no. 2and 3.
- group III: Ca(HCO3)2, Mg(HCO3)2 and NaCl are detected in samples
no. 5, 6 and 7.
- group IV: Ca(HCO3)2, MgCl2 and NaCl are detected in samples no. 12,
14 and 15.
- group V: Ca(HCO3)2, CaSO4 and NaCl are detected in samples no. 9
- group VI: Ca(HCO3)2 and NaCl are detected in samples no. 4, 10, 11 and
13.
8. The sodium adsorption ratio (SAR), of the investigated groundwater
samples ranges from 2.8 to 8.8. The groundwater in the study area can be
used for irrigation on most of these soils with the advent of low levels of
sodium hazard.
9. The sodium soluble percentage (SSP) of these groundwater samples lies
between 40.9 to 62.3%. Most of these groundwater samples permissible
for irrigation, except the sample no. 6 that is in doubtful for irrigation.
10. The total hardness in the groundwater of the investigated aquifer lies in the
hard water category. These results due to the high percentage of calcium
and magnesium in limestone.
11. The residual sodium carbonate (RSC) in the groundwater understudy
varies from -2.80 to 0.20 meq/l. All groundwater samples of this study
area are within the good categories for irrigation.
12. The residual sodium bicarbonate (RSCB) of these groundwater’s ranges
from -0.52 to2.09 meq/l. All these samples are satisfactory for irrigation.
13. The magnesium hazard (MH) value in the groundwater of the study area
varies between 29.28 to 49.09%, indicating that these waters are suitable
for irrigation.
14. The permeability index (PI), of the groundwater in the study area range
from 62.08 to 81.05 %. Most of these water samples are moderately
suitable for irrigation.
15. According to Richards classification (US salinity diagram), the salinity
hazard for the water samples of the study area is medium, high and very
high. Most of these water samples belong to the high-salinity hazard (C3).
16. According to Wilcox classification, the water quality of the study 14
groundwater samples are acceptable for irrigation purpose but one sample is not suitable for irrigation under ordinary conditions due to its high
salinity.
iii. Conclusions:
1- According to soil hydrological characteristics, it is recommended to
use pressurized irrigation systems (sprinkler-drip....).
2- Leaching is a must to get rid of soil salinity considering drainage
system.
3- selection of appropriate crops based on the content of soil salts, total
calcium carbonate and groundwater quality in the area.
4- It is essential to use the water resources wisely and efficiently as
possible to optimize the soil plant relationships.
5- Further, detailed hydrological studies are required to know the
groundwater situation in limestone.