Rivers Case Study

Question 1

Bangladesh Location

Answer 1

Between India and Burma. Asia

Question 2

Bangladesh geography (rivers, possible natural hazards, etc.)

Answer 2

• Low lying delta
• 3 main rivers - Ganga, Bramhaputra and Meghna
• Prone to storm surges, earthquakes, cyclones
• Annual floods during monsoon

Question 3

Reasons for living in floodplains

Answer 3

• Normal monsoon floods flood 25-30% of plains –> deposits silt, replenish soil moisture –> fertile
• Provide irrigation water for jute and rice
• Shrimp fisheries water

Question 4

Physical flood causes

Answer 4

• Monsoon rains: Heavy rains cause rivers to burst banks. Soil erosion also caused –> makes flood worse bc siltation
• Cyclones: Common on the coats. May push storm surges onto land, causing floods.
• Melting glaciers: Glaciers melt more in spring, increasing river discharge rapidly
• Convergence of BGM: Three of these converge in Bangladesh –> higher discharge –> during monsoon two combined cause flooding
• Tectonic uplift of Himalayas: Water coming down has greater erosion potential –> carries sediment –> chokes rivers which floods

Question 5

Human flood causes

Answer 5

• Deforestation in headwater areas: Increase in Nepal and Tibet pop., forest area cleared for fuel and grazing –> less evapotranspiration –> in Himalayas deforestation = lower interception rates and hence shorter lag time in peak discharge.
• Urbanisation of floodplains –> more impermeable surface, less vegetation = more runoff and greater floods
• Increasing pop. of Bangladesh: More people. Sinking of more wells –> water table lowers and subsidence.
• Climate Change: Glaciers melt more

Question 6

Social impacts (positive)

Answer 6

• People rely on groundwater sources –> replenished

Question 7

Social impacts (negative)

Answer 7

• Education disrupted
• Disease: 2004 flood in Dhaka 100,000 people suffered from diarrhoea bc contaminated water
• Damage to property: 2004 30 million people left w/o homes
• Loss of life: 2004 flood over 600 people killed
• Migration & displacement

Question 8

Economic impacts (positive)

Answer 8

• Agricultural businesses flourish
• Fisheries do well –> floodwaters act like nurseries to young fish.
• People employed in these sectors –> fisheries employs 1.5 m fulltime employees

Question 9

Economic impacts (negative)

Answer 9

• Victims lose land and livelihood
• Land is inundated –> 2007 2.2 million acres of cropland damaged
• Public buildings and services disrupted –> 2004, 7b dollars worth damage done to schools, and hospitals
• Govt. needs to spend for relief and aid

Question 10

Environmental impacts

Answer 10

• Returns nutrients to the soil and fertility
• Fills in wetlands –> aquatic habitat connectivity increase
• More breeding, migration and dispersion of species triggered

Question 11

Political impacts (positive)

Answer 11

• Frequent flooding allows govt. to study and mitigate severe effects
• Bangladesh provided shelter to victims of flooding in surrounding areas, hence areas may do the same for Bangladeshis

Question 12

Political impacts (negative)

Answer 12

Rivers flow through India, China and Nepal. Any activity that may affect river flow and discharge there may cause tension. Eg:- India building dams increasing sedimentation

Question 13

Flood action plan:

Answer 13

• Building embankments along the major rivers
• Plan to reduce flooding through sluice gates (controlled flooding), secondary embankments to hold excess water
• Successful - Prevented normal level floods along major rivers. Prevented flash flood along smaller eastern rivers. Protected land around some tidal rivers from saline flooding
• Unsuccessful: Doesn’t protect from higher moderate level storm surges. Doesn’t protect well from heavy annual floods from major rivers.

Question 14

Flood warning system

Answer 14

Flood Forecast and Warning Centre - sends warnings up to 5 days early. Communicated to ministries via SMS, fax etc.

• Effective but should be more community based –> allowing vulnerable communities to receive warnings in their own language

Question 15

Bridges

Answer 15

To keep villages accessible during floods.

Mini CS: Satiantoli is a village for which the community built a bridge to let residents access the highway. Lets 15000 people access. Boosted economy by allowing them to have a successful village market

Question 16

Resident Awareness/ Home solutions

Answer 16

Red crescent is teaching village members how to cope with floods, building masas (raised platforms), how to store grains etc. In a village called Niklagopal, message boards installed to teach children how to swim, how to build raised toilets etc.