Spatial Calibration and Temporal Validation of Flow for Regional Scale Hydrologic Modeling1

Abstract: Physically based regional scale hydrologic modeling is gaining importance for planning and management of water resources. Calibration and validation of such regional scale model is necessary before applying it for scenario assessment. However, in most regional scale hydrologic modeling, flow validation is performed at the river basin outlet without accounting for spatial variations in hydrological parameters within the subunits. In this study, we calibrated the model to capture the spatial variations in runoff at subwatershed level to assure local water balance, and validated the streamflow at key gaging stations along the river to assure temporal variability. Ohio and Arkansas‐White‐Red River Basins of the United States were modeled using Soil and Water Assessment Tool (SWAT) for the period from 1961 to 1990. R² values of average annual runoff at subwatersheds were 0.78 and 0.99 for the Ohio and Arkansas Basins. Observed and simulated annual and monthly streamflow from 1961 to 1990 is used for temporal validation at the gages. R² values estimated were greater than 0.6. In summary, spatially distributed calibration at subwatersheds and temporal validation at the stream gages accounted for the spatial and temporal hydrological patterns reasonably well in the two river basins. This study highlights the importance of spatially distributed calibration and validation in large river basins.     

Synthesis and evaluation of antioxidant activities of some indole-2,3-dione derivatives and analogs

In the present study, a series of novel Schiff bases of isatin were synthesized by condensation of imesatin with different aromatic aldehydes. The imesatins were synthesized by reaction of isatin with p-phenylenediamine. The chemical structures of the synthesized compounds were confirmed by means of IR, 1H-NMR, 13C-NMR, mass spectroscopy, and elemental analysis. These compounds were screened for antioxidant activity by DPPH, nitric oxide and hydrogen peroxide radical scavenging activity. In all the methods, the compound 3-(4-(3,4,5-trimethoxy benzylideneamino)phenylimino) indoline-2-one (5d) showed highest antioxidant activity because of the presence of electron donating groups and the compound 3-(4-(4-nitrobenzylideneamino)phenylimino) indoline-2-one (5f) showed the least activity because of the presence of an electron withdrawing group.     

Trends in groundwater research development in the South and Southeast Asian Countries: a 50-year bibliometric analysis (1970–2020)

Environmental Science and Pollution Research - Groundwater plays a pivotal role in sustaining the water needs of the population of South and Southeast Asia. However, long-term overexploitation and...