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HYDROLOGY OF THE INDUS BASIN (PAKISTAN)
GIS in Water Resources Term ProjectCE 394K
(Fall 2006)
By
Elizabeth Ojeh
Region of Interest Geographic Coordinates: Top: 400
N; Left: 600E;
Right: 800E; Bottom: 20
0N
Aerial Photographs of the Indus basin from Google Earth. (1)
All of Pakistan (2) Indus Delta
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Introduction Background Objective Data Gathering Data Processing Conclusions Acknowledgements References
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Introduction
The Indus River is the 12th largest river in the world and drains through most of Pakistan.
Pakistan is heavily dependent on the river as a major source of water supply. This
dependence on a single river system is a cause for concern especially as the Indus Riveris also a trans-boundary river shared by India. The teeming populations of these countriesdemand for water continues to rise and the supply from the river is no longer sufficient to
meet the demand. Groundwater availability in this region is also on the decline. Over-
exploitation of the groundwater in many areas is now causing the quality to decline.Groundwater accounts for over 40% of the irrigation needs of the region, while water
from the Indus River is relied upon to provide potable drinking water to the 130 million
people, generate power and fill the gap in irrigation demand. Dams on the main stem of
the Indus River and its tributaries produce most of the electrical energy for Pakistan(45%).
Background and Facts about the Indus
The Indus River originates from the Karakoram, Hindukush, and the Himalayan regions
along the north and north eastern borders of Pakistan. The rivers flow south towards theArabian Sea with a combined annual average volume of 178 bcm (for all major rivers)
discharged into the Indus Plains. The Indus River system forms a link between two large
natural reservoirs, the snow and glaciers in the mountains and the groundwater contained
by the alluvium in the Indus Plains of the Sindh and Punjab Provinces of Pakistan.
Climate is not uniform over the Indus Basin. It varies from subtropical arid and semi-aridto temperate sub-humid in the plains of the Sindh and Punjab Provinces, and alpine in the
mountainous highlands of the north. Annual precipitation ranges between 100 mm and
500 mm in the lowlands to a maximum of 2000 mm (water equivalent) on mountain
slopes. Snowfall at higher altitudes (above 2500 m) accounts for most of the river runoff.
The Indus Basin comprises of the Indus River, its five major left bank tributaries theJhelum, Chenab, Ravi, Beas and Sutlej Rivers, one major right bank tributary the Kabul
(Figure 1). TheIndus Waters Treaty of 1960 apportions the flows of four main rivers to
Pakistan the Indus, Kabul, Jhelum, and Chenab Rivers, and the remaining three to India- Ravi, Beas and Sutlej.
Because of the socio-economic importance of this river, its study is important to provide
information needed for its management, and to ensure that it is sustainable and able tocontinue support the population and environmental flows.
Objective
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The initial objective was to use the ArcHyro tools to evaluate the hydrology of the Indus
basin including the effects of climate and agriculture on the availability of water in theregion. However, this objective could not be fully realized because of the difficulty of
working with the DEM which contained holes in some important cells. The non
availability of substantial international climate data for as time series was also a problem.
The analysis done here was thus truncated. However, in the process of seeking outmethods around these problems, quite a bit was learnt about the many tools in ArcGIS9.
An interesting tool in particular was the use of conditional queries to set the value of a
cell. However, this tool did not do much good in this case because the problem cells areactual holes and do not exist in the raster.
Data Gathering
Data gathering was most difficult because most of the reliable data for the region is only
available commercially. Thus, the initial data for this project came from the USGSseamless data (International). There were several other DEM options, but none of them
seemed to download with ease. The data from the download came as 12 pieces of 250MB
units that had to be mosaiced together. The climate data was obtained fromworldclimate.com which had average rainfall and temperature data for cities around the
world. Data from other sources were so erratic they could not be put together to form a
modest time series. Climate data was obtained for 9 cities in the region: eight cities inPakistan and one from India just across the border.
Data Processing
The single DEM produced is then used for the processing. First the raster was re-sampled
from a 30m x 30m cell size to a 1000m x 1000m to allow for manageability. Severalother sizes were tried before settling on 1000m (200m and 500m). The computer time
and memory required to perform such operations was just unavailable because of the
sheer size of the region. The area of the Indus basin was extracted from the new DEMusing the Extract by Mask tool. However, after all of this was done several times, I
finally found someone who explained how to fill a hole in a DEM, but it could not be
done in ArcGIS. The image had to be imported into ERDAS IMAGINE to perform this
operation (image in blue background below). The screen shots shown below show the
sequence just described above (1) Raw DEM (2) DEM after mosaic operation (3) Close-up of DEM showing location of hole (red point). (4) DEM after hole has been fixed in
ERDAS IMAGINE.
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M
ajor
proble
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m hole
in theDEM
locatio
n
Location of Hole after it was fixed
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The extracted DEM was then reconditioned, filled, flow direction and flow accumulation
assigned, stream definition, catchment grid delineation, catchment polygon processing,drainage line processing, adjoint catchment, drainage point processing and drainage
density evaluation.
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The selected region contains some area outside of the Indus basin, so to determine thedrainage length of the DEM, the lines not intersecting the basin are selected, and then
subtracted from the total length of the drainage lines giving 115432401 Km.
The Indus basin temperature and precipitation varies significantly spatially and
seasonally. The charts below show the seasonal variation in temperature. The location of
the cities, like Islamabad in the high plains and Karachi at the coast gives an impression
of the spatial variation in temperature and rainfall.
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Temperature (oC)
0
5
10
15
20
25
30
35
40
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
(oC)
Karachi
KarachiManoraIslamabad(Katarian)Rawalpindi
Lahore City
Peshawar
Quetta
Average Monthly Rainfall (mm)
0
50
100
150
200
250
300
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Rainfall(mm)
Karachi
Karachi ManoraIslamabad
Lahore City
Peshawar
Quetta
Sukkur
Amritsar
Name Lat (N)
Karachi 24.90
Karachi Manora 24.80
Islamabad 33.61
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Rawalpindi 33.58
Lahore City 31.55
Peshawar 34.02
Quetta 30.25
Sukkur 27.70
Amritsar 31.63
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The rainfall distribution maps shown above also buttress the fact of the seasonal variation
in rainfall (the unit of measure, kharif, is representative of the agricultural planting
season).
Conclusion
Although not a lot of analysis was done in this term project, it is important to note thatmost of the lessons learned were done in the process of collecting the data, working with
large raster data and files, grid manipulation, and DEM hole filling. I hope to work
further in this region, so the work done here will be continued and used in a further studyof the water resources of the region.
Acknowledgements:
Dr. Maidment
Dr. Tarboton
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Dr. Ermac
Dr. McKinneyMiguel Pavon (TNRIS)
Classmates (everyone consulted in the LRC)
Friends and Family
Almighty God
References:
Pakistan water and power development authority, Annual Report 1999 2000, 2001
Asim R. Khan, M. Kaleem Ullah, Saim Muhammad, Water availability and some macro
level issues related to water resources planning and management in the Indus basinirrigation system in Pakistan 2002
Global water Partneship, Draft South Asia Water Vision 2025 Country Report -
Pakistan, 2000
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