Showing posts with label Irrigation. Show all posts
Showing posts with label Irrigation. Show all posts

Tuesday, 21 January 2014

Sustainable management-Khushab, Pakistan

Context:

In Northern Pakistan and dependent on irrigation and agriculture.

Challenges:
  1. Irrigation has not been managed well (has led to water-logging and a rise in the water-table)
  2. As the water-table rises it brings up the soluble salts to the surface 
  3. These salts are toxic to plants
  4. 8,000 families incomes dwindled as agricultural productivity declined 
Solution:
  • World Bank has invested $69million to reduce the water-logging and salinisation
  • Installed PVC pipes to allow drainage underground
  • Irrigation ditches have been lined to prevent seepage into the fields
  • Farms are used to educate farmers about sustainable water management
Successful?
  • Reduced water-logging by 50% in 2 years
  • Improved incomes per capita from $46 in 1989 to $195 in 2005
  • The average family is now 34% above the official poverty line.

Sustainable management-Great green wall, China

Where is the risk of desertification?
  • Affects 1/3 of total land area
  • Northern China most at risk as it is an arid, semi-arid and sub-humid region. (Korqin Sandy Lands)
Why are there desertification problems?

Physical:
  1. High temperatures and strong winds
  2. Sandy soils (highly permeable)=decreased water storage
  3. Loosely structured (organic material)= increased erosion
Human:
  1. Inappropriate farming practices (increased in the last 100yrs)
  2. Population pressure (increased in last 100yrs)
  3. Overgrazing
  4. Clearing land for agriculture/timber
  5. Increased irrigation (decreased water table)
  6. Over-cultivated (increased deforestation)
Extent?
  • China loses 5 billion tonnes of topsoil to erosion.
  • Due to poor managed irrigation, 1 million km2 of land is saline.
Solution?
  • To establish 350,000km2 of shelterbelt and plantation forests across North China by 2050.
  • 3 main objectives:
  1. To protect farmland and settlements from wind and water erosion.
  2. To improve land management
  3. To stabalise sand dunes and reclaim degraded land
  • So far 130,000km2 have been planted.
Sustainable?

Social:
  • Allows people to keep their way of life
  • Boosts morale (government doing something)
  • Trees are food crop, increased variety in the diet, healthier, increased Q.O.L
  • Dust reduced in the air, increased health, decreased illness, increased Q.O.L
Economic:
  • Crops are a source of income
Environmental:
  • Makes climate less harsh by providing shelter, meaning the inter-connected food web is able to thrive.
  • Shelterbelts modify micro-climates downwind.
Alternative?

Education:
  • Emphasis on appropriate cultivation techniques. 
  • Recycling of organic material in the soil.
  • Integration of other crops.
  • Planting specific tree species.
Sustainable management= It seeks to balance social, economic and environmental needs of a place.

Salinisation

Definition= The accumulation of salts (e.g. chloride, sulphate, carbonate, salts of sodium, calcium, magnesium) in the soil.

Why is it a problem?
  1. Accumulated salt crusts may be difficult for plants to penetrate.
  2. These salts are toxic to many plants.
  3. They reduce the spaces available for moisture and air in the soil.
The Process:
  • Salts are present throughout the soil but are not concentrated enough to damage plant life.
  • Occurs where land has been cleared of trees and then irrigated without proper drainage.
  • This causes the water table to rise nearer the surface lead to low vapour pressure in soil pores driving capillary action drawing moisture to the surface.
  • SALTS ARE LEFT ON THE SURFACE AS A CRUST
Fact: 80% of irrigation projects in Uzbekistan have been lost to this process

Sunday, 19 January 2014

Agriculture-Aral Sea

Location:
  • Scale= 68,000km2 (in 1964)
  • 60% lost 1964-1987
  • 90% lost by 2002
  • found between Uzbekistan and Kazakhstan
  • Fed by the Syr Darya and Amu Darya (no longer fed by the sea)
Opportunities:
  • Farmer used water for cotton (irrigation)
  • Cotton (cash crop) successfully exploited
Challenges:
  • Double salt concentration 
  • Salinisation of the sea
  • Collapse of fishing industry 
  • Native organisms have died out 
  • Lowering of groundwater levels
  • Exposed sea bed (dustbowl contaminating land several hundred km inland)
What did the government do?
  • Tried to introduce new fish species (doesn't tackle root problem)
  • Cost-benefit analysis
  • Reliance on cotton (refused to stop cotton industry)
The Kokaral Dam (completed in 2005)
  • In 2003 Kazakh. government used money from oil exports to build the dam.
  • Since 2005 North Aral water level has risen by 10m.
  • Wider variety of fish returned.
  • Now over 80 fishing boats operating in the sea.
  • 2009= 2400 tonnes of fish caught
  • Thriving fishing industry attracting people back (improved local services, more investment in agriculture)
Future of the Aral Sea

South Aral:
  • Little hope of saving major part of Aral (fewer fish, more saline, more wildlife will die out)
  • Continued desertification (Local climate will become more acute with colder winters and hotter, drier summers.
North Aral:
  • 2nd Dam funded by World bank ($126 million) will bring water level back to the port of Aralsk, is still currently some 40km from the waters edge.
Future aims for aral sea basin:

1) Develop management strategies to give sustainable water use/sustainable land resource uses.
2) Improve information base (need to plan the development of water resources in the area
3) Stop/reduce deterioration of environment
4) Improve conditions (for people and animals living close to the sea)