If one plots the tank irrigation in India and superimposes it with map of well irrigation, one may find that the two are negatively related. Which of the following statements explain the phenomenon? 1. Tank irrigation predates well irrigation. 2. Tank irrigation is in the areas with impervious surface layers. 3. Well irrigation requires sufficient ground water reserves. 4. Other forms of irrigation are not available. Select the correct answer using the code given below.

The negative spatial relationship between tank and well irrigation in India is primarily driven by geological and hydrological factors. Tank irrigation is dominant in Peninsular India because the region's hard, impervious rock layers prevent water from infiltrating the ground, making it easier to store surface runoff in natural depressions or embankments [2]. Conversely, well irrigation is concentrated in regions with deep, porous alluvial soils, such as the Indo-Gangetic plains, which possess sufficient groundwater reserves [3]. In the rocky terrain of the Deccan plateau, the lack of underground water and the difficulty of digging through hard rock make well irrigation unsuitable [3]. While tanks are an ancient method, the 'negative relationship' in a spatial superimposition context refers to their mutually exclusive geographical suitability rather than their historical sequence or the total absence of other irrigation forms. Thus, statements 2 and 3 correctly explain the phenomenon.

Sources

1. [2] Indian Economy, Nitin Singhania .(ed 2nd 2021-22) > Chapter 11: Irrigation in India > 29 1. Well Irrigation > p. 359
2. [3] Indian Economy, Vivek Singh (7th ed. 2023-24) > Chapter 11: Agriculture - Part II > Sources of Irrigation > p. 331