Abstract
Summary This study evaluates how differences in hydrological model parameterisation resulting from the choice of gridded global precipitation data sets and reference evapotranspiration (ETo) equations affects simulated climate change impacts, using the north western Himalayan Beas river catchment as a case study. Six combinations of baseline precipitation data (the Tropical Rainfall Measuring Mission (TRMM) and the Asian Precipitation – Highly Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE)) and Reference Evapotranspiration equations of differing complexity and data requirements (Penman–Monteith, Hargreaves–Samani and Priestley–Taylor) were used in the calibration of the HySim model. Although the six validated hydrological models had similar historical model performance (Nash–Sutcliffe model efficiency coefficient (NSE) from 0.64 to 0.70), impact response surfaces derived using a scenario neutral approach demonstrated significant deviations in the models’ responses to changes in future annual precipitation and temperature. For example, the change in Q10 varies between −6.5% and −11.5% in the driest and coolest climate change simulation and +79% to +118% in the wettest and hottest climate change simulation among the six models. The results demonstrate that the baseline meteorological data choices made in model construction significantly condition the magnitude of simulated hydrological impacts of climate change, with important implications for impact study design.
Highlights
Understanding the current and future temporal dynamics of the hydrological behaviour of rivers is vital for management of hydro-power generation, irrigation systems, public water supply and flood control structures (Jain et al, 2010)
This study evaluates how the choice of gridded global precipitation data sets and reference evapotranspiration (ETo) method affects baseline hydrological model parameterisation and thereby the uncertainty in simulated future climate change impacts using scenario-neutral impact response surfaces
Differences in average precipitation between TRMM3 B42 V7 and APHRODITE increase with increasing sub-catchment elevation
Summary
Understanding the current and future temporal dynamics of the hydrological behaviour of rivers is vital for management of hydro-power generation, irrigation systems, public water supply and flood control structures (Jain et al, 2010). Many global/regional datasets have been developed as an alternative or supplement to ground-based data over basins with severe climate data scarcity (Meng et al, 2014) for use in hydrological modelling studies (Andermann et al, 2012; Meng et al, 2014) These data sets include the Asian Precipitation – Highly Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE) data and satellite-based precipitation products such as the Tropical Rainfall Measuring Mission (TRMM). Whilst Thompson et al (2014) have demonstrated that the choice of ETo method affected the simulated hydrology of the Mekong and Andermann et al (2011) highlighted the significant inconsistencies that exist between different precipitation data products, including APHRODITE with TRMM-3B42 (and 3B43 data), no studies have assessed the combined effects of these two uncertainties for future climate change simulations. Six combinations of baseline daily precipitation datasets (TRMM and APHRODITE) and ETo methods (Penman–Monteith, Hargreaves–Samani and Priestley– Taylor) were used in the calibration/validation of the HySim model (Manley and Water Resource Associates Ltd., 2006), using the north western Himalayan Beas river catchment as a case study
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