Methods of rainwater harvesting:
(i) Roof top rainwater harvesting:
a) Roof tops are excellent rain catchers.
b) The rain water that falls on the roof of the houses, apartments, commercial buildings etc. is collected and stored in the surface tank and can be used for domestic purpose.
(ii) Recharge pit:
a) In this method, the rain water is first collected from the roof tops or open spaces and is directed into the percolation pits through pipes for filtration.
b) After filtration the rainwater enters the recharge pit or ground wells.

Problems associated with plastic bags, use of non-renewable resources, causes difficulties during disposal and affects environmental impacts:
Alternatives:
i) Wooden Cutlery
ii) Muslin pouches
iii) Glass Bottles
iv) Canvas Bag
v) Metal straws
Ban plastic in order to save and preserve the environment and reduce the production of Green house gases.

(i) Coal and petroleum are natural resource, formed from the degradation of biomass buried deep under the earth millions of years ago.
(ii) The formation of these fossil fuels is a very slow process and takes very long period and for renewal. So we need to conserve them.

i) The top layers of soil contain humus and mineral salts, which are vital for the growth of plants.
ii) Removal of upper layer of soil by wind and water is called soil erosion.
iii) Soil erosion causes a significant loss of humus, nutrients and decrease the fertility of soil.
iv) The direct and primary effect of soil erosion is soil loss and nutrient leaching resulting in reduction of land productivity.
v) Annual floods causes damages to crops, property and lives.
vi) Deforested rain forest soil becomes dry and nutrient-deficient as there is no longer vegetation to hold water and nutrients in place.
vii) Heavy rains further erode soil and saturate waterways with excess nutrients, disrupting the food chains of tropical ecosystems.
viii) Eroded sediments can even change the course of rivers, which suffer from huge deposits of silt from deforestation.
ix) Desertification is another possible consequence of erosion.

Sources of solid waste:
a) Municipal wastes
b) Hospital wastes
c) Industrial wastes
d) e - wastes
Solid waste management:
Solid-waste management involves the collection, treatment and proper disposing of solid material that is discarded from the household and industrial activities.
Methods of solid wastes disposal:
i) Segregation:
It is the separation of different type of waste materials like biodegradable and non biodegradable wastes.
ii) Sanitary landfill:
a) Solid wastes are dumped into Iow lying areas.
b) The layers are compacted by trucks to allow settlement.
c) The waste materials get stabilized in about 2 - 12 months.
d) The organic matter undergoes decomposition.
iii) Incineration:
It is the burning of non-biodegradable solid wastes (medical wastes) in properly constructed furnace at high temperature.
iv) Composting:
Biodegradable matter of solid wastes is digested by microbial action or earthworms and converted into humus.