Effect of different land use land cover on surface heat budget - A case study from a tropical humid region of India

Surface energy balance largely depends on the state of atmospheric variables and a change in their interrelation propagates a change in the balance. Other than the meteorological factors, land use land cover (LULC) also plays a major role deciding the proportional participation of different heat fluxes in the heat balance of an area. Delineating the effects of LULC on energy budget is rather easy over extensive areas than doing it locally, especially over the regions where the influence of any certain climatic characteristics is pre-dominant. Burdwan district in the Indian state of West Bengal is located under tropical Gangetic type climate where the influence of monsoon is at large. Mann-Kendall test at 95% confidence interval showed significant trends of the atmospheric variables over three decades there and t-test at 5% confidence level found significant difference in variables over different LULCs. The Pearson's correlation coefficients between LST and NDVI and NDBI are more than 0.81 and 0.74 respectively over different LULCs. Sensible heat flux (SHF) is found to be dominant in pre-monsoon and latent heat flux (LHF) in monsoon seasons, when an increase in minimum temperature about 1.2-2 degrees C is also noticed. Albedo, net radiation, SHF and LULC are demarcated as the principal factors by PCA analysis. The screen temperature is related to the heat fluxes and LULC by the equations - 't = 57.0166 + 1.402SHF-0.203LHF+0.25vegetation cover+0.064 urban land' in the western part and 't = 33.88-0.19SHF-0.047LHF-0.29 vegetation cover+0.76 settlement area' in eastern part of the district. Based on the interrelationship of heat fluxes and LULC, LHF is predicted to decrease in near future by 0.17% whereas SHF can increase up to 1.58% with an increase of LST and screen temperature by 1.2% and 0.88% respectively if the present rate of change in LULC sustains.