Impact of Climate Change on the Hydrological Conditions of The Noelmina Watershed, East Nusa Tenggara, Indonesia

Climate change is a phenomenon that has become a real threat to human life and the environment. Over the past 40 years, climate parameters in the Noelmina River Watershed, East Nusa Tenggara, have undergone changes. This has undoubtedly caused significant changes in the hydrological conditions of the watershed, which covers an area of 1,965,71.39 hectares. Due to the limited climate data available from the Meteorology, Climatology, and Geophysics Agency (BMKG) at the study site, Climate data from the National Aeronautics and Space Administration Prediction of Worldwide Energy Resources (POWER NASA) were used. In the last 40 years, the average air temperature at the study site has increased by 0.19 0C, relative air humidity has increased by 2.1 %, and annual rainfall has increased by 430 mm.There has also been a shift in the climate types in the watershed. Based on the criteria of Smith and Ferguson, Oldeman, and Mohr. Changes in watershed water balance were observed using the Thornwaite-Matter method. The water surplus in the Noelmina sub-watershed increased by 51.06%. The surplus period occurred between December and March. The base flow also increased by 45.8%.