6. Protective measures for non-arable lands – Contd.

Transcript

Hi friends, welcome back. In the previous lecture we studied about some of the protective measures for non-arable lands. In the present lecture, I am continuing with the same topic, the protective measures for the non-arable lands.

Gully Control Measures

Coming to the gully control measures in case of non-arable lands, vegetative filter strips. They are the main gully control measures. In this the strips of suitable plant species are planted across the water course or nullah to check the velocity of the water flow arresting the silt. This is being a semi-permanent vegetative measure adaptable in almost all the areas. So here in the vegetative plant strips are planted along the course of nullah bunds to check the velocity of water flow, and thus they arrest the silt particles. You can see this. This is the nullah bund across which the vegetative filter strips have been arranged. Whatever they do, while the water is coming out, they arrest the silk particles. In the gully control measures, we have studied what is gully formation or gully erosion.

If the sheet and rill erosion, if not controlled in the initial years through the vegetative measures, then the gullies will be formed. These are often 1-5 meter depth, depending on the rainfall, topography and soil conditions. This is very important. So when the sheet and rill erosion is not controlled by suitable vegetative measures, then they results in the gullies. They may be 1-5 meters depth as well as width. And on account of this the land is declared unfit for cultivation. So what are the control measures. Mechanical measures any earthen, masonry or stone structure constructed across the slope. And any live bund or vegetation established across the slope. To form the gully formation or to avoid the formation of gullies. There are two ways. One is mechanical structure. It may be earthen, stone or masonry related structure. And the second one is vegetative structure. Any live bund can also prevent the formation of gullies.

Coming to the brushwood check dams. So let us study, what are the gully control measures. In that brushwood check dams. These are constructed across the gullies by driving wooden pegs into the ground and then intertwining the brushwood along the driven pegs. It is adaptable in all areas, irrespective of soil and rainfall. It is a semi-permanent vegetative measure and a mechanical measure also. In this the wooden pegs have been driven into the soil, and they have been intertwined. They will be intertwined. So by this you can also see in the pictures. The whatever the gullies formed, because of the growth of the vegetation, their further expansion is restricted. By the construction of brushwood check dams, the gully formation can be avoided to a substantial amount.

Coming to the Loose Boulder check dams. These are considered gully control measures. What are loose boulder checks? These are the porous checks constructed across the nullah using loose boulders, to check the water velocity and arrest the silt. Adaptable in all areas irrespective of soil and rainfall. This is a semipermanent mechanical measure. You can have this. These are the loose boulder checks, porous boulder checks constructed across the nullah; just to arrest the runoff and also the silt particles. Whatever the silt particles, they will be held back and only pure water devoid of silt particles will be leter down.

Then coming to the rubble dam. Rubble dams are also one type of gully control measures, wherein the rubble constructions, obstructions across the water course to check the water velocity. Adoptable in all areas, semi-permanent mechanical measure. You can see this the rubble dams. All the rubble dams have been constructed across the slope, so that they can arrest the velocity of the runoff, they can arrest the velocity of the runoff and hold the moisture.

Then coming to the Drop structures. The different drop structures. In this, dams are constructed across the nullah to check the water velocity and permit the storage. Excess runoff will pass through the weir, and this is a permanent mechanical measure. What happens here. The dams are constructed across the nullah to check the water velocity and permit the storage. So these are the drop structures, where they have built dams. Here also it is being dammed, then straight drop spillway is constructed.

Next coming to the Chute Spillways. Here these are open channels with steep slopes consisting of an inlet and a vertical curve section and a steep sloped channel and an outlet. Constructed in all areas irrespective of soil and rainfall, this is a permanent mechanical measure. It can have a chute spillway. It is a deep inlet, and also outlet will be there. So the channel lights and the channel roughness will be there. So this is one of the important gully control measure formed in a non-arable land.

And lastly this is Percolation Tank. These are the embankments constructed across the natural depressions or valleys in non-arable and community land to store the runoff for percolation. Embankments are being constructed across the natural depression, so as to store the runoff for the percolation. So what will do upon the percolation, the ground water will be recharged. And the water is available for social and agricultural use at the surface level. This is a permanent mechanical measure. You can see that this is a percolation tank. They have constructed, wherever the chances, wherever the availability is there. And whatever the amount of water, quantity of water is there, it will percolate into the soil and recharge the groundwater.

So in this way the protective measure in non-arable lands undertaken are as important as agronomic measures undertaken in the arable lands. The protective measures taken in non-arable lands are as important as those of agronomic measures in the arable lands. But these measures when implemented in an appropriate precision and with proper planning in design will help in arresting the degradation. When these protective measures are adopted with a proper plan or proper planning or designing of the structures, they will help in arresting the degradation.

So with this I amending the topic. That is protective measure for non-arable lands and also I am concluding this lecture.

Thank You.