Assessment of spatial transferability of process‐based hydrological model parameters in two neighbouring catchments in the Himalayan Region

Abstract

Estimating the hydrological regime of ungauged catchments in the Himalayan region is challenging due to a lack of sufficient monitoring stations. In this paper, the spatial transferability of the model parameters of the process‐oriented J2000 hydrological model was investigated in 2 glaciated subcatchments of the Koshi river basin in eastern Nepal. The catchments have a high degree of similarity with respect to their static landscape features. The model was first calibrated (1986–1991) and validated (1992–1997) in the Dudh Koshi subcatchment. The calibrated and validated model parameters were then transferred to the nearby Tamor catchment (2001–2009). Sensitivity and uncertainty analyses were carried out for both subcatchments to discover the sensitivity range of the parameters in the two catchments. The model represented the overall hydrograph well in both subcatchments, including baseflow, rising and falling limbs; however, the peak flows were underestimated. The efficiency results according to both Nash–Sutcliffe (ENS) and the coefficient of determination (r2) were above 0.84 in both catchments (1986–1997 in Dudh Koshi and 2001–2009 in Tamor). The ranking of the parameters in respect to their sensitivity matched well for both catchments while taking ENS and log Nash–Sutcliffe (LNS) efficiencies into account. However, there were some differences in sensitivity to ENS and LNS for moderately and less‐sensitive parameters, although the majority (13 out of 16 for ENS and 16 out of 16 for LNS) had a sensitivity response in a similar range. The generalized uncertainty likelihood estimation results suggest that the parameter uncertainty are most of the time within the range and the ensemble mean matches very good (ENS: 0.84) with observed discharge. The results indicate that transfer of the J2000 parameters to a neighbouring catchment in the Himalayan region with similar physiographic landscape characteristics is viable. This indicates the possibility of applying a calibrated process‐based J2000 model to other ungauged catchments in the Himalayan region, which could provide important insights into the hydrological system dynamics and provide much needed information to support water resources planning and management.

Glacio-hydrological melt and run-off modelling: application of a limits of acceptability framework for model comparison and selection

“…For this study, three different conceptual models of snowmelt and ice melt with different levels of complexity were compared. All have been used extensively to simulate melt processes in glaciated regions around the world (e.g Matthews and Hodgkins, 2016;Ragettli et al, 2016;Gao et al, 2017;Nepal et al, 2017;Reveillet et al, 2017). The first melt model structure (TIM 1 ) employs a classic temperature index model approach (Braithwaite, 1995) whereby melt is assumed to increase linearly with temperature above a given critical threshold:…”

“…So-called "enhanced" TIM structures have also been proposed, which include added levels of complexity with the purpose of providing more accurate estimates of melt. These have accounted for perturbations in melt caused by topographic shading (Hock, 1999), surface albedo characteristics (Oerlemans, 2001;Pellicciotti et al, 2005) and debris cover (Carenzo et al, 2016).…”

Water Balance Assessment under Different Glacier Coverage Scenarios in the Hunza Basin

“…The J2000 hydrological model was selected to simulate snow cover area and runoff in the basin. The model is designed for use at different catchment scales and has been used for simulations of flow elsewhere in the Himalayan region-in the eastern catchment of the Ganges [32][33][34] and the Tibetan Plateau [35]-as well as other parts of the world. The study had three main objectives: (1) to assess the capability of the J2000 model to perform the simulations of snow cover and river flow, (2) to simulate the contribution of snowmelt and different components of glacier melt to total river discharge, and (3) to test the potential effects of different scenarios of glacier recession on ice melt and river discharge.…”

Assessing reliability of hydrological simulations through model intercomparison at the local scale in the Everest region

“…Various hydrological modelling approaches have been set up for several basins of the central Himalayas, at different spatio-20 temporal scales, from physically-oriented representations of processes, such as TOKAPI by (Pellicciotti et al, 2012) or SWAT by (Bharati et al, 2016), to more conceptual ones, such as SRM by (Immerzeel et al, 2010), GR4J by (Andermann et al, 2012) and (Pokhrel et al, 2014), GR4JSG by (Nepal et al, 2017a), SPHY by (Lutz et al, 2014), HDSM by (Savéan et al, 2015) and J2000 by Nepal et al ( , 2017b. However, large discrepancies remain in the representation of hydrological processes among several studies at a regional scale stemming from the variation in modelling applications, input data and the processes 25 taken into account.…”