الفهرس 
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Abstract
sur-mARY
This study aimed to evaluate the function of a sub-
~acedrainage system installed in an agricultural land of
oaharmis village, Imnaba , Giza covernorate in 1981, as
well as its effect on soil characteristics-and plant growth.
The study lasteo three years after the installation
of the drainage syster.l.Berseer.las winter crop and maize
as summer crop. The area of the experimental field was 48
fd, and was bound by a main irrigation canal in its norht
and by a main drain canal in its south.Sub~acefield drains
were installed at 40 Q apart and 150 ~n depth. They
connected with a collector line which led to the ffiain
drain. The rnaintenence of the drainage system and the
neasurement of discharge rate were carried out through 5
manholes.
litheexperimental field was devided into 5 plots
each bound by 2 field drains. For measuring water table
depth, each plot was supplied by 5 piezometers ~-
cular to a field drain and at a distances of 0.4 , 2.5 ,
5, 10 and 20 m.
chemically analysed. Also soil hydralic properties were
stuuied , the performance of drainage system was evaluated
and the effect of drainage on crop production was
assessed.
An evaluation on the equation which used in design the
drainage system (steady state),was done and compared with
the equations of nonsteady. state.
The obtained results can be summarized as follows:-
1 Drainable prosity anti hydraulic conductivity increased
progressively, while bulk tiensity decreased.
2 The electrical conductivity of total soluble solts
in the soil solution was 2-21 mmhosjcm/25°c in the
initial stage and decreased very sharply (0.8-13.0
mmhos/cm/250c) immediately after starting drainage
in the first year and continued its decrease during
the second and third years.
3 ’ttle &epth of water table was 0.40-0.55· m before the installation
of tile drains. After installation of drainage
, water tabl~ lowered to 0.75 m in the 1st
year, 0.65-070 m in the 2nd yea~ , and 0.53-0.57 m
in the 3 rd year. The water table was higher in the
mid-distance between any a6jacent laterals.
4 The rate of drawdown of water table increased in
the direction of the main drain in the 1 ~ year,
but it reduced thenafter as a result of rising
water in the nain drain.
5 The heighest rate of discharge was found ll~ediately
after irrigation and decreased quickley and
stilled steady after a number of days (tA)· On
the other hand, the lowest discharge rate was found
at the end of the irrigation sycle. It was found
also, that the highest disch~rgc r~to waz in the
first year and the lowest one was in the third year.
6 Using parameters of drainage intensity factor (a)
and head loss fraction (he/htot)’ the performance
of the drainage syst~~ proved ~ to very poor.
7 On the basis of hydraulic conductivity measured in
this study, existing spacing between drains (40 m)
was found too long and needed reduction by about
50 % (steauy state). This emphasizes the need for
a careful attention in stucies on soil properties’
before installing drainage project.
8 Drainage caused anincrease in maize crop by 28-52%
and in berseem crop by 24-58% • The increase was
progressive with tiem followed drainage installation,
despite the slight rise of water table in
the second and third years. Thus manifesting a
6ramatic long-term improva~ent in soil productivity
caused by drainage.