Limestone quarrying is a major economic activity across the globe. While the air quality and sediment transport implications of limestone quarries are well described, the effects on streamflow and runoff processes remain poorly understood. Using a paired catchment approach (natural and quarried watersheds), we measured rainfall characteristics and the hydrograph response to examine the changes in runoff generation, while a geochemical approach using stable water isotope and ions were used to estimate the stream transit time and source water contributions. The runoff response of the quarried watershed was substantially different from the natural watershed. The mean R/P (0.13) and peak discharge rates in the quarried watershed were two – three times higher than the natural watershed, while the response lag (26.3 min) and lag to peak (179.4 min) in the quarried watershed was significantly shorter than the natural watershed. The mean transit time (MTT) in the quarried watershed was 0.46 years and was substantially shorter than the MTT of 3.04 years in the natural watershed. The young water fraction in the quarry was 20% and was greater than the 5.2% observed in the natural watershed. These observations suggest that limestone quarry development resulted in changes to runoff and streamflow processes. The data suggests that limestone quarrying led to the higher contributions from surface or shallow subsurface flow paths during storm events while also reducing the overall catchment storage and contributions to streamflow from groundwater/deep subsurface sources. While the study sheds important light on limestone quarry impact on hydrological processes, a more detailed and long term investigation is needed where the use of other geochemical tracers and identification of more endmembers will provide more information on the processes.

Infiltration and hydraulic conductivity ( K) play a key role in streamflow generation and groundwater recharge. The impact of agriculture on soil infiltration and K has been widely investigated. While many studies show decreases in infiltration and K, others show an increase or no change in both parameters. These variations highlight the importance of conducting local scale investigations. We investigated the impact of agricultural development and land cover changes on infiltration and K. Unsaturated hydraulic conductivity (K unsat) was measured at the soil surface during both dry and wet seasons and saturated hydraulic conductivity (K sat) was measured at 25, 45, and 65 cm below the surface. Our results show that there were no significant differences in K unsat between perennial crop cover and natural forests; however, agroforests did have significantly higher K unsat than natural forests, which was attributed to higher soil moisture. There were no significant differences in K sat among the perennial crops, agroforests and natural forests at the 45 and 65 cm depths; however, at 25 cm natural forests had significantly higher K sat, which was attributed to the higher soil organic matter and lower bulk density in natural forest. The study showed that the impacts of agriculture and land cover change on K sat does not extend to deeper soil layers. We used two years of rainfall intensity data, observed K unsat and K sat , and HYDRUS-1D modelling to infer any changes to runoff. We show that footpaths and perennial crop cover may generate more surface runoff than natural forests. This study adds to the literature on agricultural impacts on infiltration and K. More importantly it shows that differences in crop type, management practices and topographic location all play an important role on infiltration and K, showing the need for local field based studies.