1.Surface water Ground water (i) Water found on the surface of the earth is known as surface water. (i) Water located below the earth's surface is known as ground water. (ii) Streams, rivers, lakes etc. are major sources or surfac water. (ii) It is stored in porous soil and rocks. (iii) It can be directly used for irrigation. (iii) In most of cases it is needed to be pumped out. 2. (i) Overpopulation or large and growing population can lead to water scarcity as more population means more demand for water. (ii) To facilitate higher foodgrain production, water resources are being over exploited to expand the irrigated areas and the dry season agriculture.