Regional Scale analysis of hydro-meteorological variables in Kesinga sub-catchment of Mahanadi Basin, India

Abstract

The spatiotemporal patterns prevailing at regional scale can be significantly different from the patterns observed at basin or country scale. The present study aims to analyse regional-scale trends (spatial and temporal) in monthly, seasonal and annual time series, and change point in annual time series of temperature (Tmax, Tmean and Tmin), rainfall, runoff and evapotranspiration in Kesinga sub-catchment of Mahanadi basin over the period 1970–2015. Non-parametric Mann–Kendall (MK) test and Sen’s slope test have been applied to assess the significance and magnitude of the trends, respectively. In the results, increasing trends are observed in Tmax, whereas, Tmean- and Tmin are following insignificant decreasing trend. Rainfall exhibits significant increasing trend in monsoon and annual time series, whereas, insignificant decreasing trend prevails in post-monsoon and winter season. On the contrary, significant increasing trends are observed in runoff at the catchment outlet and evapotranspiration in all the seasons. The change point in annual rainfall and runoff as identified using non-parametric Pettitt test is found to be in the year 2000 which is further verified using sequential MK test. The significant change in LULC of the region from forest, swamp and fallow land to cropland over time has been found to be the possible reason for the breakpoint observed in double mass curve and discrepancies in the trend of rainfall and runoff during non-monsoon season. Overall, the influence of climate variability is mainly evident in annual and monsoon series, whereas, the effect of anthropogenic variables is confined to non-monsoon seasons.