sustainability Article Streamflow Alterations, Attributions, and Implications in Extended East Rapti Watershed, Central-Southern Nepal Vishnu Prasad Pandey 1,* , Dibesh Shrestha 1, Mina Adhikari 2 and Shristi Shakya 3 1 Nepal Office, International Water Management Institute (IWMI), Lalitpur 44700, Nepal;
[email protected] 2 Nepal Water Conservation Foundation for Academic Research (NWCF), Kathmandu 44600, Nepal;
[email protected] 3 Policy Entrepreneurs Incorporated (PEI), Lalitpur 44700, Nepal;
[email protected] * Correspondence:
[email protected]; Tel.: +977-98-4131-8939 Received: 13 March 2020; Accepted: 21 April 2020; Published: 8 May 2020 Abstract: Streamflow alteration and subsequent change in long-term average, seasonality, and extremes (e.g., floods and droughts) may affect water security, which is a major concern in many watersheds across the globe. Both climatic and anthropogenic activities may contribute to such changes. Therefore, this study assesses: (i) Streamflow and precipitation trends to identify streamflow alterations in the Extended East Rapti (EER) watershed in central-southern Nepal; (ii) relationship of the alterations to climatic and anthropogenic sources; and (iii) implications of streamflow changes to the socio-environmental system. The trends in streamflow were analyzed for pre-and post-1990 periods considering the abrupt shift in temperature trend in 1990. Results showed a general decreasing trends in discharge post-1990 in the EER watershed. Human activities have significantly contributed in altering streamflow in the EER. Human-induced streamflow alterations have affected the water availability, food security, river health, aquatic biodiversity, and groundwater abstraction in the EER watershed. Keywords: climate change; East Rapti; Nepal; non-climatic change; rainfall; streamflow 1.