ts07d alghamdi mirza et al 5479 ppt€¦ · 30.5.2012 1 khalid al‐ghamdi, meraj mirza, ramze...
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Khalid Al‐Ghamdi, Meraj Mirza, RamzeElzahrany, and GomaaM. Dawod
Umm Al‐Qura University, Saudi Arabia
Saudi Arabia
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Makkah City
It is a unique city for Muslims all over the world, since it contains the holly mosque.
From a religious point of view, a Muslim should perform pilgrimage (called Hajj, i.e., visiting Makkah in specific days in the year) once in his/her life.
Thus, hundreds of thousands Muslims are gathered in Makkah yearly.
This is an important factor to be considered in analysing the urban growth of this city.
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Floods in Makkah
Periodical
Flash (high intensity in short time)
Dangerous
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Rainfall History
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0
50
100
150
200
250
300
350
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66
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68
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70
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Year
An
nu
al R
ain
(m
m)
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Topography of Makkah
Mountainous rigid topography
Heights: 138 to 982 m (average: 276 m)
Runoff comes mainly from interior wadis
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Objectives
Utilizing GIS:
1. To monitor and quantify the spatial urban sprawl of Makkah city 1947‐2010
2. To estimate flood hazards' increase over the same period
3. To investigate the urban sprawl ‐flood hazards' increase relationship.
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Available Data
Maps:
1. Topographic map of Makkah city in 1947
2. 105 cadastral maps (AutoCAD files) for 1990
3. A land use map dated 2010
and
A national 5‐meter resolution DEM
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Flood Estimation
Using the U.S National Resources Conservation Service (NRCS) Curve Number (CN) methedologloy.
It utilizes geological/Soil/Land use informationto assign a unique CN coefficient for each sub‐basin
CN used to estimate the surface runoff depth and the peak discharge magnitude.
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Processing Workflow
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Results1. Urban growth:
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Results2. Urban growth and topography:
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Results3. Urban growth and road network:
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Results4. Urban growth and geology:
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Results5. Floods in 1990:
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Results6. Floods in 2010:
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Results7. Floods vs. Urban growth (1990‐2010):
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Results
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Results
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Conclusions
1. Urban growth in Makkah city = 97% from 1990 to 2010 (with 5% annual rate).
2. Urban sprawl mainly exist in low- and moderate-elevation regions.
3. Urban development has been intensive mostly along main two highways.
4. Establishment of new residential areas was in regions that already posse high flood impacts
5. Building up new suburban areas on sediment soil significantly decreases the permeability of the soil and, thus, leads to a crucial increase in hazardous water surface runoff.
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