How does afforestation help to control flood and landslide.​

Afforestation. Trees are planted near to the river. This means greater interception of rainwater and lower river discharge . This is a relatively low cost option, which enhances the environmental quality of the drainage basin .

Trees prevent floods, landslides

They help the groundwater supply recharge, prevent the transport of chemicals into streams and prevent flooding. ... The trees' roots suck water deep from under the ground to as low as 200 feet. They hold the soil together so that erosion is prevented.

Explanation:

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which three statements are true about all alloys?

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.