Please enable JavaScript.
Coggle requires JavaScript to display documents.
Impact of Humam activity on slopes - Coggle Diagram
Impact of Humam activity on slopes
How human activity can negatively effect slope
Deforestation
The removal of trees an vegitation means there is no roots to hold the soil together or protect the ground from things such as rain splash
Road building/Construction
Weight of buildings puts pressure on slo
Excervation and movment of material from the upper slope and depositing in on the lower slope, making the lower slope unstable as there is no vegetation and soil.
Foot path trampling
Regularly used foot paths results in movement of materials
Mining and Quarrying
When mining takes place, the slope foot loses support and forms an uneven slump. this is due to vigbrations through the soil of mining equiptment and the excervated of material creates steep unsable slopes
Acid rain
Acid rain is caused by human polution
Acid rain causes infiltration and leads to the soil eroding, and this results in the surface of the slope sliding, making it more unstable.
How human activity can positivly effect slope
Afforestation
This is the re planting of forestes on slopes strentheming them up and working to intercept precipitation.
Pinning
This involves attaching wire nets to reduce rock fall
Netting
This is to colect fragments of scree which can be safely removed at a later date, it is mosly used where tourism is important
Graiding
Is the reshaping of slopes to reduce mass movment usulay to make them less steep
Drainage
This reduces the amount of water flowing down the slopes which would aid in the movemtn of material
Example of these impacts
Case study Hong Kong
Reasons for land slides in this region
Geology
There are three types of roacks in Hong Kong, sedimtary, granite and volcanic rocks with sedimentary taking up the lower ground and the other two types creating the higher ground. The high ground rocks are very weathered paticularly the granite which means that they are more prone to slope failure.
The area is prone to land slides beacuse it has a very high rainfall especaly in the rainy season (may to september). it is also made up of a lot of slopes due to previous volcanic eruptions.
Human activities
Hong Kong is densely populated with a lot of developments on the island. The constution ivloved in the development has negatvily effected the structure of the slope.
Maintenance of slopes
There has been multiple methods of reducing mass movment.
Surface drains
This allows for the removal of excess water which is important as this water increasses the likley hood of slumping. due to confusion these drains havent been maintained properly
Man made slopes
These are man made hills contain drains that redirect water away from other slopes to resucece mass movment. this is the most sucessfull procceses.
Greening techniques
Mulching systems - These provide cover for the ground, making it possible for vegitation to grow through the mat to secure it in it's place
Long root grass - These are planted on man made slopes, as a way to effectly cover and hold together the slope
Fiber reinforced soil systems - Constructed by mixing polyester fibers into sandy soil. this mixture is capable of resisting tension
What action are necessary to solve HK's landslide issue?
Hong Kongs greening techniques where vegetation is used, are what is required to minimize there land slide issue.
As the country is being built up in its infrastructure the increased excavation has an impact on the stability of slopes especially as the material is pilled up making more slopes, that are usually quite steep. These slopes and existing slopes have to be stabilized to reduce the chance of landslides. The mulching system provide cover for the ground, making it possible for vegetation to grow through the mat to secure it in it's place. this is necessary to strengthen these slopes.
Another greening technique is the planting of long root grass as there roots can help in holing the material of the slopes together and also cover the slopes reducing the effect that rain splash can have. these features make it very effective at reducing landslide risk especially considering tat this method is very low maintenance and cheep to plant.
Fiber reinforced soil system is another action that is necessary to slope stability in Hong Kong. It is where polyester fivers are mixed in to the sandy soil. This works very well as it resits tension which is needed to hold slopes together
Greening techniques are required by Hong Kong to help solve there landslide issues, as without them the slopes man made or natural are not capable of holding themselves together.
Two ways Hong Kong government has attempted to manage landslides.
Privately owned and maintained slopes - the owners are obligated to comply to government regulations as to maintenance.
research and investigation by the GEO Geotechnical Engineering Office, researches how to improve slope safety by looking at previous serious land slides.
Are these sufficient?
These two processes are some what sufficient although the reassure of GEO does seem to be more successful. The constant research leads to increasing understanding allowing for more effective management methods such as greening techniques and surface drains.
Private property management is not as sufficient as geo research as it doesn't iterate also there is no increase as time goes on. Such as what in needed in the areas where intense development these areas are more prone to land slides as material is dug and pilled up in the construction process. This material is more prone to falling meaning there is need of increase in managment. Not enough increase of private property management makes it not sufficient to reduce these events, especially as construction takes place all the time.
history of hong kongs land slides
Between 1947-1997 470 people died as a result of land slides
In june 1966 rain storms triggered massive lnadslides killed 64 people.300 millimetres of rain had fallen in ten days before compaed to the normal 130 millimetres over a year, over 2500 people were made homeless and 8000 evacutaed. after even more intence rain the area had recived 1650 millimetres of rain over 15 days. 700 land slides where recorded
