Spatio -temporal trend detection of hydro -meteorological parameters for climate change assessment in Lower Tapi river basin of Gujarat state, India

Abstract

The present research aims to assess the climate change in Lower Tapi River Basin (LTRB) of the state of Gujarat in India. The Mann-Kendall (MK) test with Sen's slope estimator and Sen's Innovative Trend Analysis (ITA) have been used for detecting the trend of the hydro-meteorological parameters-temperature and rainfall. The temperature trend during the period 1979–2014 has been analyzed using MK test and ITA method. The annual maximum, annual minimum and annual mean temperature analysis is carried out for 5 weather stations in the basin. Also, the trend has been analyzed using MK test and ITA method for annual rainfall for 9 raingauging stations for three time periods i.e. 1928–2013, 1955–2013, and 1970–2013. Most of the results obtained from these two methods for trend detection of these hydro-meteorological parameters are found to be matching. Further, the results of this study shown that the annual maximum, minimum and mean temperature increases at trend value of 0.009 °C/yr, 0.0244 °C/yr and 0.0188 °C/yr, respectively, over the LTRB during 1979–2014. The annual rainfall increases at the trend value of 2.185 mm/yr, 4.181 mm/yr and 5.495 mm/yr for the period of 1928–2013, 1955–2013 and 1970–2013 respectively. The magnitude of upward (positive) trend of annual rainfall is greater for the period of 1955–2013 and 1970–2013 in comparison to the period of 1928–2013. The spatial distribution of temporal trend of these hydro-meteorological parameters have been represented in Arc-GIS 10.3.The results of Spatio-Temporal trend distribution over the study area shown that the annual mean and annual minimum temperature indicates the upward (positive) trend over whole LTRB, while annual maximum temperature indicates the upward (positive) trend over the basin except west coastal region of LTRB. The annual rainfall exhibits upward (positive) trend in all three time periods over entire LTRB.The trend (positive/negative) detected for mean temperature and annual rainfall is found to be consistent with the trend noticed by Indian Meteorological Department for the state of Gujarat. The spatial distribution of trend further needs to be analyzed to correlate it with changing pattern of land use – land cover over a period of time. The present case study for the assessment of climate change would be useful to the water resources engineers for planning and management and policy decisions for climate change adaptation in the study area.