Managing Deserts

Managing Deserts

1. Sahel

   • main use agriculture
     • problems
       • overcropping
         • deforestation due to population increase
           • sustainability
       • overgrazing
         • traditional mix of nomadic pastoral farming
           • ... and sedentary farms
       • past inappropiate aid & cash cropping
         • for export
         • world bank - ineffective & sometimes damaging schemes - not matching local needs
           • they dug wells in hyper arid regions
             • like Mali
             • where aquifers couldn't be refilled by rainfall
               • as fast as water was being extracted
                 • enocurage people increase cattle numbers
         • NGOs working with communtiies
           • at grassroots level
             • more affortable, sel sufficient solutions - appropiate to local needs
               • Eden Foundation
                 • farmers Burkina Faso
                   • plant edible perennials
                     • to stabilise soil & stop wind erosion from rain
                     • shelter crops & soil from wind too
                       • stopping erosion & increasing yield
                         • 300% yield increases
   • vast international region
     • different countries manage different ways
   • Stone Lines
     • dry conditions creep southwards
       • not much rainfall
     • rainfall destructive not useful
       • as rainwater can't infiltrate baked bare soil
         • fertile soil carried away
     • Burkina Faso farmers
       • install stone contour lines
         • and use of fertiliser
         • cereal harvest
           • central B.F. plateau doubled
             • within few years
         • these slow surface runoff
           • increasing water infiltration
             • soils more nutritious so more yields
             • 200 more litres water penetrate soil per 1m2
         • sediment captured
           • behind semi-permeable barriers
         • Oxfam - provide spirit levels to improve stone sighting
       • takes them about 100/150 unpaid days per hectre
   • Solar Oven
     • metal paraboloidal reflector
       • reflects sunlight
         • generates heat to cook the food
     • main purpose to use less wood
       • stop deforestation
     • no fuel & cheap/easy to build
       • no CO2 emissions
     • can sterilise water
       • heat kills bacteria
     • but ...
       • later in the day when there's no son it's useless
     • local employment
       • saves fueld gathering time for productive use
   • Green Wall
     • 15km wide, 7775km long
       • wall of vegetation from Dakar to Djibouti
         • 11 countries
       • to restore 15million hectares of land
     • local people get income for planting
     • praised by UN as 'global answer'
     • trees improve soil quality
       • for farmers
       • slow wind speeds/ rain filters
         • less land enroachment
     • may not be maintained properly once done
     • expensive $3 billion
       • yet to start in 10/11 countries
     • will only be fully completed 20 years after planting begins

2. South-West USA

   • Agriculture
     • water for irrigation
       • salination, lower water table, water rights conflict
     • based on cattle
     • growing nuts/veg/cotton
   • Mining
   • Tourism
     • water use
   • Water Allocation
     • Colorado River Basin gives water to 40 mil people & 5.5 million acres of land
       • water resources divided
         • Lower division
           • Nevada
           • California
           • Arizona
         • Upper divsion
           • Colorado
           • New Mexico
           • Utah
           • Wyoming
         • upper not allowed to deplete water for lower in agreement
           • aided agriculture and tourism
             • not enviroment
               • some main tributaries of river dried up
                 • tension with mexico over salt deposits on the mouth of river
               • states argue over calculations
   • Drip Irrigitation
     • controlled realease of water
       • directly to roots of vegetation
     • conserves water
       • growth of crops
     • reduces salinization
       • from capillary action
     • Arizona peanut & veg farms
     • harvests improved
       • less need for chemical fertilisers
         • improved natural soil fertility
   • Sustainable tourism
     • needed due to more roads more cars more soil erosion
       • roads demolish vegetation
         • worse soil fertility
           • so should drive on dirt tracks
     • buses/coaches not cars
     • group trips
     • protect natural/historic assets
   • increasing population due to immigration