The Bushe-Poladpur contact is one of the most important stratigraphic boundary separating the middle Lonavala Sub-group from upper Wai Sub-group in the Western Deccan Traps. In this paper, physical volcanology textural and petrochemical finger printing, crystal size distribution and shape preferred orientation studies (SPO) is integrated with paleomagnetic and AMS studies to correlate lavas across five localities transcending the Bushe-Poladpur boundary, south of Pune city. The flows belonging to the Bushe Formation are highly inflated, compound pahoehoe lavas, with plagioclase-olivine-phyric, coarse grained diktytaxitic textures. The flows belonging to the Poladpur Formation are transitional between pahoehoe and aa (rubbly pahoehoe lavas), with or without multi-tiered entablature showing fine-grained, olivine-phyric glassy textures. CSD studies indicate that the Bushe lavas have lower plagioclase crystals per unit area (1.11×10⁻⁴/µm²), low average effective nucleation rates (2.60× 10⁻¹²/µm³s) and high average effective growth rates (1.22×10⁻⁵µm²/s) for intact crust time than the Poladpur lavas that have higher plagioclase crystals per unit area (8.31×10−⁴/µm²), high average effective nucleation rates (3.46×10⁻¹¹/µm³s) and lower average effective growth rates (2.24×10⁻⁶µm²/s) akin to their emplacement dynamics and cooling histories. There is a stark contrast in the magnetic susceptibilities (Bushe- 24759.8 × 10⁻⁶ SI; Poladpur-29178.02 ×10⁻⁶ SI) across the Bushe-Poladpur contact. There is a general similarity between the SPO of the primary silicates (plagioclase) to the AMS derived directions. The divergence in AMS directions across the Bushe-Poladpur contact in the study area can be attributed to complex interplay of local paleotopography and slope, lava flow field dynamics, inflation and inversion of topography, style and emplacement mechanism of flow units. Generalisations and over simplifications of delineating lavas and deciphering their flow direction on a single criteria (tool) or single ghat (road section), outcrop or sample will have disastrous consequences while mapping large and complex lava flow fields. Thus, a multi-disciplinary approach needs to be the norm for characterising, correlating and mapping lavas across formations that transcend the K-Pg boundary in highly dissected ancient continental flood basalt province like the Deccan Traps.

Runoff has increased many fold in urban areas due to increase in paved areas, training of streams and construction of storm water drains. The recharge is therefore continuously decreasing; resulting in depleting groundwater reserves beneath large cities, especially those situated on water divides. In order to reduce surface runoff and replenish groundwater many advocate artificial recharge through rainwater harvesting. Conventionally, detailed hydrogeological survey is needed by expert hydrogeologists to suggest suitable sites for rooftop rainwater harvesting and storage in the subsurface aquifers. Pune, a rapidly growing city, is under severe stress due to shortage of water in some areas. An effort has been made in this study to identify areas suitable for rooftop rainwater harvesting by integrating traditional hydrogeological survey data with the help of Remote Sensing and Geographic Information System. This endeavour has led to develop a program called SLUGGER-DQL which helps to identify potential sites for rooftop rainwater harvesting and artificial recharge. The program is open ended and several other factors controlling potential recharge can be easily added on. Based on the results of the present study, potential sites for rainwater harvesting and artificial recharge have been identified in the Pune University-Shivajinagar-Kothrud area. The present paper demonstrates the utility of traditional hydrogeological surveys combined with modern techniques in solving problems related to urban hydrogeology and town planning.