This paper aims to identify the groundwater-potential zones in coastal zones of the Cuddalore district by integrating remote sensing, Geographic Information System (GIS), and Analytical Hierarchy Process (AHP) techniques. The thematic layers such as geomorphology, landuse/land cover, lineament density, geology, soil, drainage density, rainfall, and slope are considered for the identification of groundwater-potential zones. The groundwater-potential zones are categorized into five zones as ‘very good’, ‘good’, ‘moderate’, ‘poor’, and ‘very poor’. From the study, it is observed that the rainwater/surface water infiltration to the aquifer is high in the eastern region due to flat topography, and thus, these zones possess ‘very good’ and ‘good’ groundwater-potential zones. The groundwater potential in the central region of the study area possesses moderate infiltration capacity, which is suitable for agricultural practices. Moreover, it is also observed that the groundwater potential is ‘poor’ and ‘very poor’ in the northwest region due to steep slopes in which suitable recharge structures should be constructed in these zones to harvest the rainwater. Eventually, the obtained results are validated with existing bore wells in the study area, and it reveals that a GIS-based integrated method is an effective tool for the exploration of groundwater resources with high accuracy.

In this study, the discharge coefficients (C_d) of SMBF flumes under free and submerged flow conditions were analytically investigated. The dimensionless parameters involved in the discharge coefficient, derived from the dimensional analysis, are the contraction ratio [r_crn = ratio of flume width (w) to channel width (B)], relative head (h_w: the ratio of the upstream head (h) to the $$w$$w ) and, in the case of submerged flow, also the submergence ratio [ $$S_{{\text{r}}} = h_{{\text{t}}} /h_{{\text{u}}}$$S r = h t / h u : downstream flow depth ( $$h_{{\text{t}}}$$h t ) to upstream flow depth (h_u)]. C_d decreases logarithmically from 1.2 to 0.75 in the range of $$h_{w}$$h w between 0.4 and 1.8. The submerged condition does not reduce the $$C_{{\text{d}}}$$C d , but it reduces the discharge capacity (up to 50%), so that in some cases, to pass a given flow discharge, $$h_{{\text{u}}}$$h u should increase by about 100% compared to the free condition.