8/3/2019 Geomorphic Engineering

1/31

Devashis Chatterjee

Geomorphic EngineeringIssues For Research,

And Some Awkward Questions

Devashis Chatterjee

8/3/2019 Geomorphic Engineering

2/31

Devashis Chatterjee

Water as resource

Water for human use comes from rivers,ponds, wells

All ultimately derived from rain

8/3/2019 Geomorphic Engineering

3/31

Devashis Chatterjee The Water Cycle

8/3/2019 Geomorphic Engineering

4/31

Devashis Chatterjee

Four questions

Renewable?

Sharing silt? Affect area

Geomorphology involved?

8/3/2019 Geomorphic Engineering

5/31

Devashis Chatterjee

Renewable

Renewable or perennial?

Boundary conditions of replenishment

Thresholds of behaviour

Decision

8/3/2019 Geomorphic Engineering

6/31

Devashis Chatterjee

Rivers ofIndia

8/3/2019 Geomorphic Engineering

7/31

Devashis Chatterjee

Artificial

lake

8/3/2019 Geomorphic Engineering

8/31

Devashis Chatterjee lake

8/3/2019 Geomorphic Engineering

9/31

Devashis Chatterjee

?

Discharge changes

Slope stays

Braiding/ meandering switch

Vulnerable to shift

Who is affected?

8/3/2019 Geomorphic Engineering

10/31

Devashis Chatterjee

Patterns

8/3/2019 Geomorphic Engineering

11/31

Devashis Chatterjee

Braided

Spiti

8/3/2019 Geomorphic Engineering

12/31

Devashis Chatterjee Braid to meander

8/3/2019 Geomorphic Engineering

13/31

Devashis Chatterjee

equilibrium

8/3/2019 Geomorphic Engineering

14/31

Devashis Chatterjee Ganga bankline

8/3/2019 Geomorphic Engineering

15/31

Devashis Chatterjee

Threshold

Discharge

vs

slope

8/3/2019 Geomorphic Engineering

16/31

Devashis Chatterjee

Colorado

water

sediment

8/3/2019 Geomorphic Engineering

17/31

Devashis Chatterjee

River changes

8/3/2019 Geomorphic Engineering

18/31

Devashis Chatterjee

Channel reduction

8/3/2019 Geomorphic Engineering

19/31

Devashis Chatterjee

Above

dam

8/3/2019 Geomorphic Engineering

20/31

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

8/3/2019 Geomorphic Engineering

21/31

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.

8/3/2019 Geomorphic Engineering

22/31

Devashis Chatterjee

Response

time

8/3/2019 Geomorphic Engineering

23/31

Devashis Chatterjee Delta dynamics

8/3/2019 Geomorphic Engineering

24/31

Devashis Chatterjee Brahmaputra

8/3/2019 Geomorphic Engineering

25/31

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

8/3/2019 Geomorphic Engineering

26/31

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

8/3/2019 Geomorphic Engineering

27/31

Devashis Chatterjee

delta

8/3/2019 Geomorphic Engineering

28/31

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

8/3/2019 Geomorphic Engineering

29/31

Devashis Chatterjee

Research ideas

Lessons of experience

Monitoring of geomorphic change

Network of information

Application of new tools of observation

analysis

8/3/2019 Geomorphic Engineering

30/31

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

8/3/2019 Geomorphic Engineering

31/31

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