Definition of Erosion – Erosion comes from the Latin erosionem (meaning to gnaw) or also called erosion is an event that occurs naturally by the erosion of solids (sediment, soil, rock, and other particles) due to transportation by wind, soil and other materials under the influence gravity or by living things, such as animals that make burrows or the growth of plant roots that cause cracks in the soil, in this case it is called bio-erosion.
Erosion is not the same as weathering due to weather, which is the process of destroying rock minerals by chemical or physical processes or a combination of both. In general, erosion involves three processes, namely detachment , transformation , and sedimentation .
The erosion that occurs can form many interesting natural features such as mountain peaks, valleys and coastlines. Erosion is actually a natural process that is easy to recognize, but in most places it is exacerbated by human activities in poor land use, deforestation, mining activities, plantations and cultivation, construction or development activities that are not well managed, and road building.
Soil used to produce agricultural crops is usually subject to much greater erosion than soil with natural vegetation. The conversion of forests into agricultural fields increases erosion, because the strong root structures of forest plants that bind the soil are replaced with weaker root structures of agricultural crops.
Definition of Erosion
According to the Big Indonesian Dictionary (KBBI), erosion is a condition of eroding the earth’s surface by forces that involve lifting objects such as flowing water, ice, wind, and waves or currents. Furthermore, based on the explanation at dpupkp.bantulkab.go.id , erosion or erosion is a process of moving rock mass from one place to another which is carried by transporters moving over the earth.
Quoting from the 2010–2014 National Disaster Management Plan owned by the National Disaster Management Agency (BNPB), it is stated that Indonesia has the potential to experience erosion due to changes in the shape of the soil or rocks. This occurs due to the forces of water, wind, ice, to the influence of heavy age or living organisms.
In general, soil erosion is a process or event of loss of the topsoil surface, either caused by the movement of water or wind. This erosion process can cause a decline in soil productivity, soil carrying capacity and environmental quality.
The surface of the earth’s crust will always experience a process of erosion, in one place erosion will occur while in another place landfill will occur, so that its shape will always change over time. This event occurs naturally and takes place very slowly, so that the consequences only appear after tens or even hundreds of years later.
Erosion is also the process of loss or erosion of soil or parts of land from one place that is transported by water or wind to another place. Eroded soil transported by runoff will be deposited in places where the flow of water slows down such as rivers, irrigation canals, reservoirs, lakes or river mouths. This has an impact on the shallowing of rivers, resulting in more frequent floods during the rainy season and droughts during the dry season.
Erosion is one of the processes in watersheds (DAS) that occurs as a result of land use that is not in accordance with land capabilities. Erosion is also one indication to determine the criticality of a watershed. The amount of erosion and sedimentation from year to year will increase if there is no control or prevention.
Factors Causing Erosion
The amount of erosion depends on various influencing factors including climate, vegetation, soil characteristics, land use, and topography. Climatic factors, including the amount and intensity of rain or precipitation, average and temperature ranges, as well as seasonality, wind speed, storm frequency. Geological factors including sediment type, rock type, porosity and permeability, land slope. Biological factors include the vegetation cover of the land, the creatures that live in the land and land use by humans.
Generally, with the same ecosystem and vegetation, areas with high rainfall, high frequency of rain, more frequent exposure to wind or storms are certainly more exposed to erosion. Sediments with a high content of sand or silt , located in areas with steep slopes, are more easily eroded, as are areas with weathered or broken rock.
Porosity and permeability of sediment or rock have an impact on the speed of erosion, related to whether or not water seeps into the soil easily. If water moves underground, less surface runoff is formed, reducing surface erosion. Sediments that contain a lot of clay tend to erode more easily than sand or silt. The impact of sodium in the atmosphere on the erodibility of the clay should also be considered.
The most variable factor is the amount and type of land cover. In untouched forests, soil minerals are protected by a layer of humus and organic layers. These two layers protect the soil by dampening the impact of raindrops. the layers along with the litter on the forest floor are porous and easily absorb rainwater.
Usually, only heavy rains (sometimes accompanied by hurricanes) will cause runoff on the ground surface in forests. If trees are removed by fire or logging, the degree of water infiltration is high and erosion is low. Severe fires can also cause marked increases in erosion when followed by heavy rains. In this case, construction activities or road construction, when the topsoil or topsoil is removed/compacted, the degree of susceptibility of the soil to erosion increases.
Roads, in particular, allow for an increased degree of erosion, because in addition to removing land cover, roads can significantly change drainage patterns, especially if an embankment is made to support the road. Roads that have lots of rocks and are hydrologically invisible (can catch water as quickly as possible from the road, by imitating natural drainage patterns) have a great chance of not causing increased erosion.
Determinants of Erosion Occurrence
In addition to the several main factors mentioned above, in the Journal of Civil and Environmental Engineering Vol. 3 No. 1 , also describes the four determinants of erosion. These factors include:
Topography or the elevation of the earth’s surface can also trigger erosion. Topography will cause differences in slopes. The slope and length of the slope are very influential on surface flow and erosion.
Soil is the next determining factor. Several things from soil conditions that can cause erosion include the soil’s resistance to damage caused by rainwater or surface activity and the ability of the soil to absorb water.
The determining factor for the last erosion is vegetation. The presence of vegetation on the surface of the earth will affect runoff and erosion. These influences include:
- Rain intercept done by crop crown processing.
- Vegetation that affects the speed of flow on the surface and the destructive power that comes from the water.
- Plant roots will affect biological activities related to plant growth and will affect soil fertility.
- Transpiration that occurs will make the soil drier.
Activities related to changes in factors that affect erosion, for example changes in land cover due to deforestation or clearing of forests for settlements, agricultural land, or
grazing. Changes in topography on a micro basis due to the application of terracing, loosening the soil by processing, and the use of stabilizers and fertilizers that affect soil structure.
The process of clearing land that is not controlled will have implications for increasing the risk of erosion. The main cause of erosion is land use that is not in accordance with its function and the level of sensitivity of the soil which is very sensitive to erosion. Land damage that occurs due to the high level of sensitivity of the soil to erosion as a result of human activities in managing land use that is not in accordance with conservation principles.
It is customary for the community to start farming in months with high rainfall, both for rice fields, cultivation and plantations. It can be observed that at the beginning of the growing season the vegetal cover area decreases , so that land without vegetation is vulnerable to erosion. The wider the farmer’s land, the greater the erosion caused.
Cultivation activities with the habit of burning the planting area repeatedly can damage the soil surface both for organic loss and soil erosion. Forest management activities such as logging, building roads, ditches and base camps must receive special attention in conserving forest resources. The same goes for other development sectors such as road network construction, mining, agriculture, transmigration, and settlements that deforest the land surface.
There are many types of erosion that occurs on the surface of the earth. There are several examples of erosion which are explained as follows.
1. Water Erosion or Ablation
The first example is water erosion. This erosion occurs due to the influence of river water and rain. High intensity and rainfall will further increase the chances of ablation. At least, there are four types of ablation that can occur.
- Splash erosion: caused by rainwater that falls into the ground and washes away the soil.
- Sheet erosion: occurs in soil on mountain slopes. The top layer of soil will be washed away with rainwater.
- Erosion of grooves: erosion of the soil that is already taking place and causes the formation of grooves which later become places for water to flow.
- Trench erosion: erosion that occurs when the groove that is formed has a depth of more than 0.3 meters.
2. Erosion Corrosion or Deflation
Deflation is erosion caused by wind. Usually occurs in desert areas. The wind in that place will cause the sand to move to another place constantly.
Abrasion is the erosion that occurs in coastal areas. The erosion occurs because of the destructive sea waves and ocean currents. According to BNPB in Indonesia’s Disaster Risk , it also explains that the abrasion process occurs when there is wind moving at sea which causes currents and waves towards the coast. If the incident lasts longer, it will cause a lot of erosion on the beach.
This erosion is caused by the movement of melting ice. This melting causes the rocks to move downward and then precipitate. The results of this erosion are known as fjords . This occurrence is usually in the snowy mountains.
The impact of erosion is the depletion of the top layer of soil, which will reduce land capability (land degradation). Another consequence of erosion is the decreased ability of the soil to absorb water (infiltration). A decrease in the ability of land to absorb water into the soil layer will increase surface water runoff which will result in flooding in rivers.
In addition, soil particles that are transported by surface runoff will eventually settle in rivers (sedimentation) which in turn due to high sedimentation will cause siltation of rivers which will affect the smoothness of shipping lanes.
A certain amount of erosion is actually a natural occurrence and good for the ecosystem. For example, gravel periodically descends to lower elevations via water transport. However, excessive erosion, of course, can cause problems, for example in terms of sedimentation, ecosystem damage and simultaneous loss of water.
Erosion causes the loss of fertile and good soil layers for plant growth, as well as reduced soil ability to absorb and hold water. The transported soil will be carried into water sources (sediment) and will be deposited in places where the water flow slows down in rivers, reservoirs, lakes, reservoirs, irrigation canals, above agriculture and so on.
Thus, the damage caused by erosion occurs in two places, namely in the soil where erosion occurs, and in the final destination where the transported soil is deposited.
How to Prevent Erosion
The phenomenon of erosion in the top layer of the earth’s surface can actually be prevented in various ways. Quoting from Pusatkritis.kemkes.go.id , there are several ways to prevent erosion. Here’s an explanation.
1. Soil Conservation
The first way that can be done is to do soil conservation. This effort is made to prevent and inhibit soil erosion. Selection of the right vegetation is the key to the success of conservation efforts. Make sure to use vegetation that has the ability to withstand various stress conditions.
We may already be familiar with the terracing system which is usually found on agricultural land in the highlands. This terracing actually has a very important role, especially in keeping rainwater from flowing down and causing erosion. With terraced land, the soil will be more stable and the plants will also grow better.
3. Counter Farming
The next effort to prevent soil erosion is by contour farming or planting based on contour lines. This method of cultivating crops will make the roots of the plants stronger, so they can hold the soil so that it doesn’t erode easily during heavy rains.
The next preventive measure that can be taken is reforestation or replanting of deforested forests. This method is very important to do because trees in the forest are oxygen producers as well as water retainers. With a forest ecosystem that is maintained, other natural disasters such as floods can also be prevented.