EFFECT OF HYDRO-PHYSICAL PROPERTIES OF SOME NEWLY RECLAIMED SOILS AT NUBARIA AREA ON DRAIN SPACING AND SUBSURFACE DRAINAGE COST (original) (raw)

The current study was conducted on a newly reclaimed area of about 1000 feddans at Nubaria Agricultural Development Region, West of the Nile Delta, Egypt. The objective of this study is to perform a pre-investigation for the selected area which include studying some physical and chemical properties, as well as defining, depths of the water table, impermeable layers and their effects on the calculation of drain spacing. Or subsurface drainage system installation costs. To fulfill these objectives twenty eighte test-wells were drilled down to 2 m depth in a grid system (400X400) m to determine some soil physical and chemical properties, soil samples were collected from the tested wells for chemical analysis, i.e., soil texture class, total calcium carbonate, soil reactions, soil salinity. The water table depths were measured three times per week during the investigated period to identify water table depth and its fluctuation. The test wells were boring to reach 5 m depth to identify the depth of impermeable layers and also, soil samples from these barriers were collected for determining the above mentioned analyses. The obtained results revealed that, the texture of the selected soil profile and impermeable layers varied from sandy loam to sandy clay. Calcium carbonate content in soil samples ranged from 6.58 to 21.3 %, with an average of 11.42%, while, in the impermeable layers it ranged from 3.70 % to 15.58 %, with an overall average 8.04 %. The hydraulic conductivity (K) values in the studied area varied from 0.45 to 5.56 m/day with an average of 1.91 m/day. The hydraulic conductivity (K) has indirect effect on the field drain cost and the correlation represented by logarithmic equation: (Drain spacing =89.27 ln (field drain cost)- 0.476), R2 = 0.8969). The electrical conductivity values showed that sixty percentage from soil samples are non-saline , while 16.7, 10.0 and 13.3 % are low saline, medium and high saline , respectively. The measured impermeable layer depth represented by 11.1 %, more than 5 m while 44.5 and 44.4 % located at depth between (1-3) and (3-5) meters below soil surface, respectively. The indirect effect of impermeable layer depth on field drain cost represented by logarithmic equation: (drain spacing =30.514 ln (field drain cost) + 58.873) , R2 = 0.9917). Water table depth varied from 0.7 to 3.96 m below soil surface with an average of 2.61 m below soil surface. Although no irrigation was applied in the area for long time, 25.93 % from the measured water table was less than 2 meters and 74.07 % of the measured water table depths located between 2 and 4 meters depth from soil surface. The salinity of the ground water ranged from non-saline (1.0 dSm) to moderately saline (7.3 dS/m). The calculated SAR values showed that no problems can be expected, since the values are generally low. Field maps using Kriging technique were produced for the soil surface level, depth of the impermeable layer and EC maps.