摘要：In this study, a semi-distributed conceptual hydrological model “HBV-Light” is applied to one of the snow fed basins “Narayani River Basin” in Nepal to estimate runoff at several gauging stations and to analyse the changes in catchment hydrology and future flood magnitude due to climate change. The model was calibrated for the period 1995-2005 and validated for the period 2006-2008 with satisfactory results producing values of Nash-Sutcliffe coefficient between 75.2% and 82.6% during calibration and 56.3% and 87.2% during validation for all the four sub-basins. The value of coefficient of determination (R2) during calibration is between 0.789 and 0.844 and during validation is between 0.629 and 0.893. Due to the structural complexity, the model underestimates the low flows, whereas the peaks were correctly estimated except for some sharp peaks due to isolated precipitation events. Further, the volumetric error during the calibration period is acceptable. Contribution of snowmelt to annual, summer (March-July, MAMJJ) and winter (November-February, NDJF) runoff at the final outlet gauging station (Narayani River at Narayanghat) is 15.72% (avg.), 26.22% (maximum in year 2002) and 0.42% (minimum in year 1996) respectively. Sensitivity analysis (increased temperature) indicates that global warming leading to increase in average basin temperature will significantly lead to higher contributions to runoff from snowmelt. The model simulates an overall increase in monthly stream flow from January to June (34% to 51%) and November-December (10% to 15%) with the output of HADCM3 GCM, A1B scenario.
关键词：Hydrological modelling;Climate change;HBV light model;Narayani river basin
