A multimodel ensemble approach to assessment of climate change impacts on the hydrology and water resources of the Colorado River Basin

Abstract

Abstract. Implications of 21st century climate change on the hydrology and water resources of the Colorado River Basin were assessed using a multimodel ensemble approach in which downscaled and bias corrected output from 11 General Circulation Models (GCMs) was used to drive macroscale hydrology and water resources models. Downscaled climate scenarios (ensembles) were used as forcings to the Variable Infiltration Capacity (VIC) macroscale hydrology model, which in turn forced the Colorado River Reservoir Model (CRMM). Ensembles of downscaled precipitation and temperature, and derived streamflows and reservoir system performance were assessed through comparison with current climate simulations for the 1950-1999 historical period. For each of the 11 GCMs, two emissions scenarios (IPCC SRES A2 and B1, corresponding to relatively unconstrained growth in emissions, and elimination of global emissions increases by 2100) were represented. Results for the A2 and B1 climate scenarios were divided into three periods: 2010-2039, 2040-2069, and 2070-2099. The mean temperature change averaged over the 11 ensembles for the Colorado basin for the A2 emission scenario ranged from 1.2 to 4.4 • C for periods 1-3, and for the B1 scenario from 1.3 to 2.7 • C. Precipitation changes were modest, with ensemble mean changes ranging from −1 to −2% for the A2 scenario, and from +1 to −1% for the B1 scenario. An analysis of seasonal precipitation patterns showed that most GCMs had modest reductions in summer precipitation and increases in winter precipitation. Derived April 1 snow water equivalent declined for all ensemble members and time periods, with maximum (ensemble mean) reductions of 38% for the A2 scenario in period 3. Runoff changes were mostly the result of a dominance of increased evapotranspiration over the seasonal precipitation shifts, with ensemble mean runoff changes of −1, −6, and Correspondence to: D. P. Lettenmaier (dennisl@u.washington.edu) −11% for the A2 ensembles, and 0, −7, and −8% for the B1 ensembles. These hydrological changes were reflected in reservoir system performance. Average total basin reservoir storage and average hydropower production generally declined, however there was a large range across the ensembles. Releases from Glen Canyon Dam to the Lower Basin were reduced for all periods and both emissions scenarios in the ensemble mean. The fraction of years in which shortages occurred increased by approximately 20% by period 3 for both emissions scenarios.

Climate-driven disturbances in the San Juan River sub-basin of the Colorado River

“…Climate change in the CRB is anticipated to cause large impacts to water resource sustainability (Christensen and Lettenmaier, 2007;Rasmussen et al, 2014;Dawadi and Ahmad, 2012). However, to our knowledge, few modeling studies have considered the impacts of climate change coupled with changes in vegetation (Buma and Livneh, 2015;Carroll et al, 2017;Pribulick et al, 2016).…”

La variabilidad histórica de la corriente del Río Colorado. El vínculo con la minuta 319

“…En la primera década del siglo xxi se llegó a los niveles más bajos de reservas en las presas. Los modelos a largo plazo, algunos para el 2050, otros para el 2100, indican que se dará un incremento en la temperatura de la cuenca de 1.8º a 4.5º centígrados (Christensen y Lettenmaier, 2006). Por otra parte, las proyecciones de crecimiento de la población para todas las entidades de la cuenca indican que en los próximos años las tensiones para el abasto urbano se incrementarán notablemente (Nowak, Hoerling, Rajagopalan y Zagona, 2012).…”

“…Dado que supuestamente no se realizó dicha definición, ante las prospectivas de un siglo xxi seco (Cook, Ault y Smerdon, 2015) el tema se vuelve importante en función de una necesaria cooperación binacional. Ante ello se han generado gran cantidad de textos con el fin de que ambos países propicien medidas alternativas ante una condición de la naturaleza que parece irremediable: el cambio climático y sus consecuencias en los procesos productivos, el abasto urbano, la producción de energía eléctrica, la pesca y su relación con la conservación del medio ambiente (Christensen y Lettenmaier, 2006). En diferentes medios de comunicación se ha establecido un vínculo que conlleva a una relación que consideramos debe ser matizada: la variabilidad del flujo del río Colorado se debe al cambio climático.…”

Past and future changes of streamflow in Poyang Lake Basin, Southeastern China

“…In addition, climate change may even be speeded up in the future, consequently leading to an increase in probabilities of floods and droughts. Therefore, changes in water resources and the underlying driving forces due to climate changes have become research focuses (Andréasson et al, 2004;Christensen and Lettenmaier, 2007;Frederick and Major, 1997;Gül et al, 2010;Lins and Slack, 1999;Liu and Cui, 2009;Null et al, 2010;Piao et al, 2007;Thodsen, 2007;Vörösmarty et al, 2000;Xu et al, 2010;Zhang et al, 2001). Andréasson et al (2004) discussed the impacts of climate change on streamflow under three anthropogenic CO 2 emission scenarios with a hydrology model (HBV) and concluded that the influences of climate change based on hydrology cycle varied geographically.…”