Analysis of non-parametric trend and climatic parameter homogeneity tests in a data-scarce region: a spatio-temporal perspective in the Tawang River basin, Eastern Himalayas

This study is aimed at studying long-term historical and future (1950-2099) trends for the RCP 4.5 and RCP 8.5 on approximately 30-year timescale at annual and seasonal for precipitation and at annual, seasonal, monthly, and diurnal temperature ranges (DTR) for temperature maximum (T_max), temperature minimum (T_min) variations using statistical trend analysis techniques-Mann-Kendall test (MK) and Sen's slope estimator (S) and the homogeneity test using Pettitt's test. The study is carried out in three spatial points across the Tawang Chu in the district of Tawang, Arunachal Pradesh. The summer mean precipitation for RCP 4.5 (2006-2065) shows a positive trend with Z = 0.126 (2006-2035), Z = 0.205 (2036-2065) for point 1; Z = 0.080 (2006-2035), Z = 0.200 (2036-2065) at point 2 and Z = 0.048 (2006-2035), Z = 0.205 (2036-2065) at point 3, with a rise in precipitation between 1.56 and 9.94 mm in all the study points. The mean annual precipitation statistics for all the points show an increase for RCP 4.5 in 2006-2052 and 2053-2099 timescale. During the study, all points in both RCPs 4.5 and 8.5 display a uniform rise in mean annual T_min (Z = 0.260 to 0.738) and T_max (Z = 0.329 to 0.674). Still, the inter-decadal temperature statistical analysis shows that the increase in mean annual T_min is greater than the increase in T_max, indicating a decreasing trend in DTR. It is anticipated that this study's outcomes will contribute to a better understanding of the relationship between change in climate and the regional hydrological behaviour. It can benefit the society to develop a regional strategy for water resource management and can serve as a resource for climate impact research scope- assessments, adaptation, mitigation, and disaster management strategies for India's north-eastern region.