Effect of Groundwater Level on Soil Moisture, Soil Temperature and Surface Temperature

The dynamic behavior of groundwater level effects the soil moisture, soil temperature and surface temperature. In the study, the effect has been studied at two observation sites with varying groundwater level. Regular measurements of soil moisture and soil temperature were taken in field at 1.5, 2.2 and 3 m depth to observe the groundwater level effect on these parameters. Preliminary analysis during November 2016-April 2017 was carried to find the relationship among soil moisture, soil temperature and surface temperature with groundwater level at each observation depth. Soil moisture and groundwater level has shown strong negative correlation (R-2 = 0.734, depth 1.5 m; R-2 = 0.799, depth 2.2 m and R-2 = 0.852, depth 3.0 m) at shallow groundwater level site and weak correlation (R-2 = 0.578, depth 1.5 m; R-2 = 0.501 and R-2 = 0.339, depth 3.0 m) at deep groundwater level site. Soil temperature and groundwater level has also shown strong positive correlation (R-2 = 0.840, depth 1.5 m, R-2 = 0.862, depth 2.2 m and R-2 = 0.917, depth 3.0 m) at shallow groundwater site and poor correlation (R-2 = 0.573, depth 1.5 m; R-2 = 0.468, depth 2.2 m and R-2 = 0.428, depth 3.0 m) at deep groundwater site. Soil moisture and soil temperature were also found strongly correlated (R-2 = 0.701, depth 1.5 m; R-2 = 0.602, depth 2.2 m and R-2 = 0.731, depth 3.0 m). Further, LANDSAT-8 data during observation period was processed to retrieve land surface temperature (LST) which in addition was correlated with soil moisture, soil temperature and groundwater level. LST was found significantly correlated with soil moisture and soil temperature at shallow groundwater site. However, a strong positive correlation, i.e., R-2 = 0.874 was deducted between LST and groundwater level at shallow groundwater site and poor correlation, i.e., R-2 = 0.434 at deep groundwater site. Thus, we have seen that shallow groundwater level has significant effect on these observed variables. The empirical results support our basic hypothesis and suggest further work for the better understanding and coupling of relationship among these parameters.