874 
occur within 24 hours. 
Evaporation generally far exceeds the rainfall. 
Relative humidity varies considerably. It is highest 
in August (62 per cent) and lowest in April 
(36 per cent). Wind occurs throughout the year. 
Mean monthly maximum temperature fluctuates 
between 39.4C 0 and 42.3C 0 for about seven months 
from April onwards. 
2.3 Geology 
The eastern half of the region represents a part of the 
Lower Indus Alluvial Plains formed over Tertiary con 
solidated sediments, which crop out abruptly as two 
monoclinal hills with fairly flat tops. Of these the 
smaller one occurring in the north, represents the seat 
of the old city of Hyderabad, while the larger one 
situated in the south is called as Ganja Hills locally 
known as Ganjo Takkar. The western half of the region 
lying west of the Indus River is largely composed of 
consolidated beds of moderate to low dip (10-2°). 
The river bed lies in a vast syncline, the corresponding 
anticline of which lies near the western boundary of 
the region (LIP, 1965-66). 
The exposed rocks are of Middle Eocene age Laki 
Series and consist of alternating beds of limestones and 
shales. The Limestones are lenticular in structure with 
intercalations of Marl. The exposed beds are weathered 
upto a depth of 5 meters from the ground surface. The 
weathered part, though porous, cannot hold or transmit 
sufficient quantity of water due to its Marly nature. 
The lower beds of limestones have intercalated chalk 
and cavities filled with calcite crystals (Wadia, 1966). 
The shales are extremely hard posing difficulty in 
drilling. A test hole drilled in the saddle between the 
monoclinal hills showed that the alluvium is resting on 
a bed of shale about 8 meters thick and occurs at a 
depth of 3 to 6 meters from the land surface (WAPDA, 
1979). In the north-western corner of the region Lower 
Eocene deposits (Ranikot Series) are exposed. The 
sediments consists of alternating beds of shales, 
sandstones and limestones. These beds are extremely 
dissected. A section of the regional geological map 
(Abu Bakr and Jackson, 1964), is presented in Fig.l. 
Fig.l Adapted Regional Geological Map with hydrologi 
cal conditions as studied through aerial photo inter 
pretation . 
3 REVIEW OF PREVIOUS STUDIES 
Before 1979 no concrete affort had been made to 
study the urban drainage conditions of the region. 
Some earlier reports illustrated the drainage conditions 
keeping in view largely the agricultural aspects (Beg, 
etal., 1970). Soon after independence in 1947, a sate 
llite town was planned on the Flood Plains adjoining 
rock outcrops to accomodate the great surge of migra 
ting population from India. Apparently no site specific 
studies were undertaken for urban planning. 
3.1 WAPDA Southern Zone Planning Studies 
Keeping in view rapid deterioration of drainage, the 
Southern Zone Planning (WAPDA 1979), conducted a 
comprehensive study. According to the main findings 
of the study "three serious difficiencies, which both 
directly and indirectly, have aggravated the drainage 
problem of the city. Firstly, the city has no surface 
drainage system for disposal of storm water creating 
critical conditions during unusual downpour of high 
intensity in most monsoon years. Secondly, due to 
lack of surface and subsurface drainage the watertable 
in Latifabad (a satellite town of the region) has come 
up close to the surface causing heavy damage to the 
residential buildings and other infrastructures. 
Thirdly, the sewage system for Latifabad and the city 
area is under-designed and that too has not been 
properly maintained, resulting in chocking of main 
sewerage lines and blockage in the connecting sewerage 
pipes". 
The study of soils was carried out during monsoon 
season when surface ponding and subsoil wetness were 
at peak. The observations were recorded on rigid 
grid pattern, at an intensity of 16 observations per 
square kilometer in newly developed area and 8 
observation per square kilometer in remaining areas. 
Using Earnest's auger hole method only 21 hydraulic 
conductivity tests were carried out at the rate of 
one test for every 250 hectares. The soil profiles 
were though examined in respect of texture, struc 
tures, porosity and ground watertable, but overall 
emphasis had been on texture with which all the 
findings were ultimately correlated. The textures 
in turn, were grouped in four broader classes: 
coarse, coarse medium, coarse fine and fine. The 
soil profile information was recorded according to 
prefixed depth intervals of 25 cms. Texturally 82 
percent of the newly developed area and 67 percent 
in the remaining parts of the region, other than 
rock outcrops, was declared to have good drainage 
conditions. 
For estimation of surface drainage, infiltration rates 
were presented in relation to textural distribution. 
Accordingly, about two-third of land was described 
as having good surface drainage. Most of the remaining 
area was reported to be with moderate drainage 
conditions. The extent of soils with poor drainage 
was found to be not more than 15 percent. 
The internal drainage of the region was determined 
from an array of hydraulic conductivity tests, despite 
great variation in results. The K-value of 60 percent 
of the profiles was less than 0.1 meter per day, 
indicating poor internal drainage. But unfortunately, 
the results are presented as average of all the 
sites studies, which came to 1.53 meter per day. 
Through the average values the diverse hydraulic 
conductivity results were described to be supporting 
the textural representations. The causes of variation 
in K-value within the generalized textural groups 
were not explained. 
3.2 Soil Survey Inventories 
By the year 1979, adequate technology was available 
in Pakistan in respect of modern physiographic soil 
surveys based on aerial photo interpretation. Through 
this technique, reconnaissance soil survey of the 
areas ar< 
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