Hydrology of the Indus Basin by Elizabeth Ojeh

8/2/2019 Hydrology of the Indus Basin by Elizabeth Ojeh

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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

Hydrology of the Indus Basin by Elizabeth Ojeh

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