The Horse 2020/21

Environment & Technology

Water erosion

11. May 2021 Laurice-Senn Team Zurich M18a, Soil4Life (0)
What is water erosion?
 
Water is arguably the most powerful tool for erosion, thanks to its great ability to move objects from one place to another. Water erosion, then, is the detachment and transport of soil material by water. This process can be natural or it can be facilitated by human activities.
 
For example, when humans cut down too many trees and plants, the soil is left bare and loose and therefore more easily moved by water. Water erosion removes the surface of the earth. Its rate ranges from very slow to very fast, depending on various factors such as soil type, prevailing weather conditions, and local topography.
 
The process of water erosion involves discrete phases, from the impact of raindrops to the development of gully erosion. Each phase has its specific processes and characteristics. These phases result in the different types of water erosion.
 
Types of water erosion
 
1. intermediate rill erosion
 
Inter-rill erosion describes the movement of topsoil by rainfall and the resulting surface runoff. It is also referred to as raindrop erosion. While it is primarily caused by rainfall, inter-rill erosion can be accelerated by factors such as slope, topography, vegetation cover, and climate.
READ: What is a sand dune: formation and types of sand dunes.
 
This type of erosion is the first and most critical step in the overall process of water erosion. It depends largely on the type of precipitation that occurs at a particular time or place. Inter-rill erosion includes the following subtypes of water erosion:
 
Spray erosion - When raindrops fall on the ground, they may have sufficient kinetic energy so that their impact can cause the detachment and movement of small soil particles.
 
Clod erosion - When heavy rain falls on bare soil, the water flows down a gently sloping terrain as a clod, detaching soil particles in somewhat uniformly thin layers.
 
Runoff - When precipitation exceeds the infiltration rate of the soil, the excess water runs off as surface runoff. Precipitation may be in the form of heavy rain or snowmelt. The turbulence of surface runoff has the potential to cause more erosion than the initial impact of raindrops.
 
2. rill erosion
 
Rill erosion results from the concentrated flow of water in small streams. These small streams are usually triggered by rainfall and carry soil with them. Rill erosion is the second phase in the overall process of erosion.
 
3. gully erosion
 
Gully erosion describes the detachment and transport of soil by larger streams of water. It digs gullies at least one meter deep into the soil. It is virtually impossible to smooth these gullies through normal agricultural mechanisms.
 
4. bank erosion
 
Riparian erosion occurs when fast-flowing streams and rivers cut into the banks. This type of water erosion often occurs at the lower end of stream tributaries. It also occurs in streams with a more shallow gradient. Bank erosion can cause large masses of soil to slide off and damage surrounding fields.

City trees in ZH - Research

4. January 2021 Laurice-Senn City trees, Team Zurich M18a, IDAF20 (0)

Areas in Zurich: 
9032 hectares (2018) --> 90.32 square kilometres
- Agricultural area               9.5%
- Forest area                    26.4%
- Traffic area                     14.6%
- Settlement area              47.7%
- Area of water bodies        1.2%
- Unproductive area            0.6%

Motor vehicle fleet:
- Passenger cars:         134'713
- Motorbikes:                23'581

Drive type:
- petrol engine:            63.7%
- diesel engine:            31.5%
- hybrid:                       3.2%
- electric motor:             1.1%
- other:                         0.5%

Electricity origin Zurich:
- Refuse and wood           1.65%
- Photovoltaics / Wind      1.27% 
- Hydropower                 24.9 %
- Nuclear power               6.69% 
- Electricity mix                9.11%
- Paraffin                        10.98% 
- Diesel                            8.83%
- Petrol                            3.79%
- Wood, biogas & environmental heat and solar collectors 2.64%
- District heating               3.3%
- Natural gas                   17.75% 
- Fuel oil                           9.09%

CO2 emissions:
CO2 emissions per capita 1.31 tonnes per year
City of Zurich Population: 415,467
= 544,261.77 tonnes of emissions caused by persons
CO2 emissions of companies in Zurich: 355738.23
Number of companies in Zurich: 6,037
= 58.93 tonnes on average per company
900,000 tonnes of CO2 per year in the city of Zurich

400 planes per day (June 2019)
134713 cars + 23581 motorbikes (June 2019)
10991 trains on Swiss tracks --> thereof in Zurich 1100

https://www.zuerich-co2.ch/ 

Trees:

80 trees for 1 ton of CO2 per year
Beech and chestnut trees convert twice as much on average
23,681,619 M2 forest area in Zurich
1 tree per M2
=23'681'619 trees in the forest

 

City trees in ZH - Experience

4. January 2021 Laurice-Senn City trees, Team Zurich M18a, IDAF20 (0)

Review and evaluation of what has been done and what remains to be done

We have drawn up a plan to realise everything we want to achieve

All in all, we hardly had any problems. The only thing that can be a thorn in our side is the coronary gland, which makes the survey and interview difficult.

We try to stick to the plan and work through everything step by step.

This week we will contact Andrea Gion Saluz to organize an interview. Maybe this will help us enormously in the other things

Laurice & Michael

CO2 neutral cities

4. January 2021 Laurice-Senn City trees (0)

We want to use a calculation to evaluate how many trees are necessary to make a city like Zürich CO2 neutral.

  • What kind of trees convert the most CO2 into oxygen?
  • How long does it take a tree to convert the full amount of CO2?
  • Costs of 1 Three?
  • How much space does a tree need?
  • Is the number of the trees possible to compensate the whole CO2 emission?
  • Is the number of trees required realistic in relation to the amount of space in a city?

We will illustrate our results with a benefit analysis and will explain it in a report. à (Costs, amount of space required, Purchase price, service costs needed)

 

We will make a survey with random people, friends, and our classmates. à About the CO2 emission per person.

 

We plan an interview with a person from an organisation, which want to plant trees or to regulate the CO2 in the air over Zürich.

  • How much money it will cost, to make a city climate neutral
  • What are the main goals?
  • When should the target be reached?
  • What are the possibilities?

[please upload the image again in the correct way]