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8/3/2019 Geomorphic Engineering
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Devashis Chatterjee
Geomorphic EngineeringIssues For Research,
And Some Awkward Questions
Devashis Chatterjee
8/3/2019 Geomorphic Engineering
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Devashis Chatterjee
Water as resource
Water for human use comes from rivers,ponds, wells
All ultimately derived from rain
8/3/2019 Geomorphic Engineering
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Devashis Chatterjee The Water Cycle
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Devashis Chatterjee
Four questions
Renewable?
Sharing silt? Affect area
Geomorphology involved?
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Devashis Chatterjee
Renewable
Renewable or perennial?
Boundary conditions of replenishment
Thresholds of behaviour
Decision
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Devashis Chatterjee
Rivers ofIndia
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Devashis Chatterjee
Artificial
lake
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Devashis Chatterjee lake
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Devashis Chatterjee
?
Discharge changes
Slope stays
Braiding/ meandering switch
Vulnerable to shift
Who is affected?
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Devashis Chatterjee
Patterns
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Devashis Chatterjee
Braided
Spiti
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Devashis Chatterjee Braid to meander
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Devashis Chatterjee
equilibrium
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Devashis Chatterjee Ganga bankline
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Devashis Chatterjee
Threshold
Discharge
vs
slope
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Devashis Chatterjee
Colorado
water
sediment
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Devashis Chatterjee
River changes
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Devashis Chatterjee
Channel reduction
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Devashis Chatterjee
Above
dam
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Devashis Chatterjee
Degradation below dams
Yellow R
Sanmexia
4.0m/66km
4yrs
South SaskatchewanDiefenbaker
2.4 m/8 km
12 yrs
ColoradoHoover
7.1 m/111 km
14 yrs
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Devashis Chatterjee
alluviation
Flood plains are built by alluviation
This happens during floods
In tamer rivers of Europe and NAmerica floods at 80% bank height in50 years
In monsoon Himalayan rivers?
Indus estimate 10 m. silt in 5000 yrs.
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Devashis Chatterjee
Response
time
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Devashis Chatterjee Delta dynamics
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Devashis Chatterjee Brahmaputra
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Devashis Chatterjee
Nile Delta
Accretion stopped after Delta Barrage1868
Western side of Rosetta promontoryretreated 6 km 1900-1991
Before Aswan rate of retreat 20m/yr
By 1991 rate was 240m/yr
From 1984-2001 120 m/yr
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Devashis Chatterjee
IGCP 475
Conceptual model for the behaviour of low-latitude, high-load Monsoon Asia Pacificrivers and deltas (compared to better-studied'type' systems from North America andEurope)
Better constraints on sediments fluxes toAsian margins and the world ocean Capacity-building and scientific advancement fordeveloping nations of the region Identifyfuture threats and possible mitigation ofgeohazards in deltaic setting
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Devashis Chatterjee
delta
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Devashis Chatterjee
Impact Analysis
Concerned with biota
Effects of process modification would
cascade
Area affected is defined by river basin,notmeasurable in kilometres
Cost/Benefit is asymmetric
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Devashis Chatterjee
Research ideas
Lessons of experience
Monitoring of geomorphic change
Network of information
Application of new tools of observation
analysis
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Devashis Chatterjee
Information
Not available in the public domain
Restrictions on topographic data
Red tape on river, climate and otherthematic data
No window
Bigger budget, more hurry
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Devashis Chatterjee
Geomorphologists
Whether from geology or geographyapproach
Have these as low priority
Role of academics
Role of professional agencies
Still talking only to each other
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