Monday, November 2, 2015

Environmental Issues


Soil erosion and land degradation are perhaps the greatest environmental issues facing most regions and societies at this time. Although irrevocably linked to deforestation and pollution problems, soil erosion is bigger than the sum of these two crises combined. 

All agricultural practices depend on a stable and productive soil for their long term sustainability. Soil erosion leads to the gradual loss of fertility in the landscape. Soil is a living entity that is formed gradually through ecological and geological processes.

Soil degradation is the loss of production and in turn the loss of dependent plants and animals. Land degradation is not a new phenomenon, Human societies have been degrading environments through their cultural practices for thousands of years. 

Perhaps the root cause of soil erosion is mankind's general lack of understanding of the complex natural systems  (i.e.plant phrenology)  that constantly interact to produce dynamic and stable global ecosystems

Today the scale of the impact is greater due to exploding human populations, and unsustainable agricultural practices and urban development.

 Scour Protection

Runoff and soil erosion are among the major environmental threats related to agricultural land use in Europe.
Geomorphic responses of rivers and catchments to major landuse distures such as floods, droughts, vegetation clearing and extreme events may trigger a rapid sequence of fluvial responses of sand and gravel filling the former reservoir.

 Stream channel instability resulting in river erosion and changing angles-of-attack can contribute to bridge scour. Debris flow can also have a substantial impact on bridge scour in several ways. A build-up of material can reduce the size of the waterway under a bridge causing contraction scour in the channel.

Seven  in 10 skip waste soils, Soil and Landscape Consultant Tim O'Hare, tests contain the carcinogen Benzo(a)pyrene, and he estimates that around one-quarter could contain asbestos.

  Impervious pavements

 Impervious pavements deprive tree roots of aeration, eliminating the "urban forest" and the canopy shade that would otherwise moderate urban climate. Because impervious surfaces displace living vegetation, they reduce ecological productivity, and interrupting atmospheric carbon cycling.

Controlling storm water flow over impervious areas is a multidisciplinary ecoScript where

  •  Impervious surfaces collect solar heat in their dense mass. When the heat is released, it raises air temperatures, producing urban "heat islands", and increasing energy consumption in buildings. 
  • The warm runoff from impervious surfaces reduces dissolved oxygen in stream water, making life difficult in aquatic ecosystems.

    Clean Water

    Compliance with the Clean Water Act mandatory erosion and sediment control devices must be installed on construction sites to minimize the release of soil into runoff waters. 

    Many construction sites have relied on straw bale and silt fence barriers. Straw bales have been proven ineffective due to inappropriate placement, bad installation and the nature of their structure. 

    Silt fences require expensive manpower for installation, inspection maintenance and removal. Silt fences cannot be placed on a slope or across a contour line and are not effective unless trenched or keyed in. 

    If not installed at a consistent elevation, silt fences will actually cause erosion. 

       Biodiversity Offsets

     Biodiversity offsetting is a method intended to help compensate for the detrimental impacts of development on biodiversity. 

    iBodiversity offsetting is a system used predominantly by planning authorities and developers to fully compensate for biodiversity impacts associated with economic development, through the planning process.
    Such an approach is designed to work by creating a credit based market that developers could use to offset actions deemed harmful to the environment by investing in habitat restoration for biodiversity elsewhere 

    The idea results in losses of biodiversity at an impact site is compensated for by the generation of ecologically equivalent gains elsewhere, resulting in ‘no net loss’ of biodiversity'.

    In some circumstances, biodiversity offsets are designed to result in an overall biodiversity gain. 
    Offsetting is generally considered the final stage in a mitigation hierarchy, whereby predicted Biodiversity impacts must first be avoided, minimized and reversed by developers, before any remaining impacts are offset. The mitigation hierarchy is used to meet the environmental policy principle of "No Net Loss" of biodiversity alongside development.[1][2]

    The legal and institutional dimensions of biodiversity are a highly top­i­cal and increas­ingly pop­u­lar approach used to com­pen­sate for impacts on species and ecosys­tems as a result of devel­op­ment, and is the sub­ject of a large and grow­ing body of sci­en­tific research.   Acknowledging the limitations of what can be achieved through biodiversity offsetting is important if we are not to wake up one day and discover we have lost what we cannot replace.