Classification of disasters

Based on the causes of the occurrence of the disaster can be grouped into 2 (two) that is a disaster because the factors of nature and disaster caused by human errors. Disaster caused by natural factors such as earthquakes, tsunamis, mountain erupt, etc. They called Natural Disaster.

While the disasters cause of human errors such as the failure of buildings (broken-down embankment, bridge / building collapse, etc.), bomb terror, social unrest, war etc.

However, in addition to the above example, there is a disaster that is a combination of natural factors and human errors.

Examples of disaster due to natural factors and human errors are:

1. Flood

Nature factor: the flood occurred because the level of rainfall is high in the headwaters area, so capacity is not sufficient and river flood occurred in the area of flood plains and downstream areas.

Human error factor: flooding occurred because the deforestation was increasing so that the surface erosion occurs when rain and then the ability of soil to absorb water in a rain reduced / lost. Increased flow of surface water that ultimately flows to the river all the capacity is limited. There were floods. Other cases are flooding in dense population areas or settlements where urban drainage channels are not being built properly.

2. Landslides

Nature factor: rock weathering that occurs due to changes in temperature by heat of the sun and rain changes throughout the year, also because of corrosion activity in the belly of magma volcanoes. Rock weathering caused the thick layer of soil from time to time. When adding soil layer thickness occurs at the slope then boosted power to be reduced so that the slope stability reduced. Slopes that are less stable when it was increasing the water saturation at the time of rain added to the burden on the surface it will be easy slope landslides occur.

Human error factor: canyon slopes or landslides may occur by human activities such as cutting, housing, road development, mining etc. All of which can disrupt the stability slopes.

3. There are many more examples of the disaster of a combination between natural factors and human errors we can find such as drought, famine etc.

In the above combination of disasters can cause one of the factors such as natural or human errors but it is often the result of both factors together.

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The influence of the rainy season is too long

Currently in some areas are presented on a long rainy season. When we see a seasonal cycle in the tropics, particularly Indonesia, in the normal condition of the rainy season falls in the month of October - April and the dry season occurs in April-October.

In April there's turnover in the rainy season to dry season. Change this pattern, marked with a range of days is not that the long rains, winds blow much faster. Are in the month of October is vice versa.

Cycle can be shifted only one or even two months so that the number of days in the rainy season or dry season becomes longer or shorter.

Now we have tread the middle of June and the rain is quite swift and still can not ascertain whether the rainy season will end soon. Indeed, some regions in Indonesia that have already entered the dry season. Then, if the impact area for the rainy season is longer?

It can have positive impact and negative

Positive impact:

• On areas that often experience drought, the longer rainy season cause the areas have supply of water more and planting the garden for longer. Water supply in the catchment areas of water such as reservoirs and lakes will supply for agriculture and drinking water in the dry season.
  

Negative impact:

• On urban areas, the flood danger still threatens, because in this times, the rain cycle is harder to predict. Sometimes a heavy rain came suddenly in a short duration but that result in a flood-prone.

• On areas such as agriculture that have a cycle three (3) monthly planting in rice fields, then at the end of May until mid-June will enter the second harvest. Still occur when the rain season harvest will be many problems, such as rice field soil is still wet even have a still stagnant water, drying of rice that are difficult to do in the open because the rain does not tend to be predicted. For rice field areas that prone water stagnated due the river overflow, they also threatened the harvest failed, because with the heavy rain could trigger flooding and river overflow swamp area rice field. Rice will be harvested before damage.

• In the side of health, change the season to trigger a shift in physical adaptation to the season also shifted. Because basically extended rainy season this was not the real rainy season. This is the turn of the season is longer than usual. And this condition will force our bodies to adapt to change and extreme weather can cause a decrease in resistance of the body cause health disturbances.

So, if the turn of the season is longer such as this time, we need to take early preventive measures against negative impacts that can befall us and the environment around us.

The latter, when in fact the natural conditions such as this to cause physical and material loss, whether this can be categorized as a natural disaster?

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Select the first flood or Landslide?

Indonesia awarded by God with the forest area of the mountains which are spread in all corners of the country. So beautiful green carpet is seen. Moreover, if the rainy season, every corner of the empty land around us, grass and shrub is growing so fast. The beautiful panorama is still clearly visible at the time I first small around 1980's.

What beauty is still there until now? If we go to rural areas may still be, but it will be very difficult to meet again in the urban areas. Because the shrub also do not have the right to live there, let alone the forest.

How the fate of our mountains? Some still look natural with a dense tropical forest. But most have very fate of concern. Barren, arid and no sir. While the mountains with dense forests are still many who have experienced landslides. The end result is the same damage to nature.

Perhaps the description above is not an issue that we need to think about because it is hundreds and even thousands of times we hear and natural without any settlement. Whether there is still little awareness of us? If so, I may be the description the following can give a little description of why it can happen, and why floods and landslides continue the seemingly never stopped.

Flood Phenomena

Genesis flood here I only discuss it in the beginning of the headwaters and the river does not discuss about the problems in urban areas that do not lose the complexity.
Hydrological cycle in which the ideal natural conditions, the rain water that fell in the river headwaters
three things happen, namely:

• direct the water flow in the surface soil and into rivers,
• water bottle up by plants ago trickle into some of the land and have some of the flow on the surface and have a vapor return,
• water that seep into ground water.

What if the natural conditions were not ideal, for example, a few plants?

1. Surface flow will be greater, causing soil erosion which will flow along the rivers. So the river became shallow.
2. Water seep into the ground a little more because there is no storm water plants, as the rain and the soil erosion. But the ground water supplies diminish.
3. When rainfall is very high then the flow along the surface sediment will flow downstream to the swift river in spate and the surrounding area. There were floods.

So the outline, one of the causes of the occurrence of flooding in lowland areas of both urban and low is the deforestation in the headwaters area. The cause is poor drainage system, decreasing the infiltration of water due to a settlement and others.

Landslide Phenomena

As I was on the definition of polecat landslides and soil movement in the post earlier, several factors have triggered the occurrence of landslides. When we are talking landslide problem then our attention is on the slope condition. Are slopes causing landslides that bald?

What about the slopes with dense vegetation that? The answer is no landslides have direct contact with the vegetation above, both lush and barren.
The main disturbance is the occurrence of landslide slope stability. Interference can be due to natural and human activities.
Natural causes are:

1. increasing layer thickness due to soil weathering rock layer below the soil due to the volcano activity. Here's the explanation: In the beginning slopes have a thin layer of soil (ideal) so that the slope is stable, although the dense vegetation to grow. Because of the activity in the magma of the earth, the heat generated to spread around and the rock layers of a layer of rock weathering on the outside, and eventually into the ground slopes become unstable due to soil layers thick add more burden on slopes prone to landslides and even surface form of the forest.
2. earthquake
3. river flow which is very swift at the time of rain, causing the river canyon, which is a foot slope tergerus.
4. rain water in the sink in the slope and restrained by a waterproof layer of rock under the soil layer on the slope so that the soil becomes unstable because of water saturated.

While the cause is due to human activities:

1. loading slope for residential development and other buildings
2. cutting foot slope to build houses, roads and other buildings without the cliffs make cultivation post-amputation. For example, the land barrier wall, plaster, etc.
3. wild mining material in the bottom of the river which is a foot slope. Elevation basis with a decrease in river slope then becomes unstable. And landslides.

May still be many other causes that I have not mentioned.

Keeping the mountain or forest?

In addition to natural factors as the causes of floods and landslides that can not be avoided, then there are some dilemmas that occur in an effort to save the hills and forests in the headwaters.
To avoid flooding the condition of water infiltration areas should be as much as possible. With the forest so dense a flood of business is possible. However, on slopes that are not stable, then the existence of the forest with a high level of infiltration is a disaster because it is vulnerable to landslides.
So we need to know the point-prone areas and provide a priority action to save the mountain or forest. Prevent erosion or flooding.
How easy is the most natural condition as the original. But it's not nearly as possible, yet the condition of natural fact we have so sad.
So far all the readers that we can do, what about our actions to reduce the occurrence of factors triggered floods and landslides in our beloved country, the disaster will be reduced so that in the future?

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