The representative elementary watershed (REW) approach proposed by Reggiani et al. was the first attempt to develop scale adaptable equations applicable directly at the macro scale. Tian et al. extended the initial de...The representative elementary watershed (REW) approach proposed by Reggiani et al. was the first attempt to develop scale adaptable equations applicable directly at the macro scale. Tian et al. extended the initial definition of REW for simulating the energy related processes, and re-organized the deriving procedure of balance equations so that additional sub-regions and substances could be easily incorpo-rated. The resultant ordinary differential equation set can simulate various hydro-logical processes in a physically reasonable way. However, constitutive and geo-metric relationships have not been developed for Tian et al.'s equation set, which are necessary for the thermodynamic watershed hydrological model to apply in hydrological modeling practice. In this work, the constitutive equations for mass exchange terms and momentum exchange terms were developed as well as geo-metric relationships. The closed ordinary differential equation set with nine equa-tions was finally obtained.展开更多
In the complementary relationship (CR) between actual and potential evapotranspiration, wet envi- ronment evapotranspiration (Ew) is usually calculated using the Priestley-Taylor (P-T) equation. Based on the data obta...In the complementary relationship (CR) between actual and potential evapotranspiration, wet envi- ronment evapotranspiration (Ew) is usually calculated using the Priestley-Taylor (P-T) equation. Based on the data obtained from 38 catchments of the Haihe River basin and the Weishan experiment site in Shandong Province of China, this study has found variations in the Priestley-Taylor parameter α (e.g. increase in values with increase in the amount of precipitation on annual scale, seasonal fluctuation noted to be at a maximum during winter and at a minimum during summer, and increased values in the forenoon and decreased values in the afternoon on an hourly scale). This paper explains that the in- ter-annual variation in α is due to the negative feedback of atmosphere in response to changes in ac- tual increase in evapotranspiration, which is weakened because the atmosphere system is open. The parameter α undergoes a seasonal fluctuation brought about by seasonal changes in advection be- tween continent and ocean; α likewise undergoes a daily variation as a result of atmospheric hysteresis in response to the changes in land surface energy.展开更多
基金the National Natural Science Foundation of China (Grant No. 50509013)
文摘The representative elementary watershed (REW) approach proposed by Reggiani et al. was the first attempt to develop scale adaptable equations applicable directly at the macro scale. Tian et al. extended the initial definition of REW for simulating the energy related processes, and re-organized the deriving procedure of balance equations so that additional sub-regions and substances could be easily incorpo-rated. The resultant ordinary differential equation set can simulate various hydro-logical processes in a physically reasonable way. However, constitutive and geo-metric relationships have not been developed for Tian et al.'s equation set, which are necessary for the thermodynamic watershed hydrological model to apply in hydrological modeling practice. In this work, the constitutive equations for mass exchange terms and momentum exchange terms were developed as well as geo-metric relationships. The closed ordinary differential equation set with nine equa-tions was finally obtained.
基金Supported by the National Natural Science Foundation of China (Grant No. 50509011)the Major State Basic Research Development Program of China (973 Program) (Grant No.2006CB403405)
文摘In the complementary relationship (CR) between actual and potential evapotranspiration, wet envi- ronment evapotranspiration (Ew) is usually calculated using the Priestley-Taylor (P-T) equation. Based on the data obtained from 38 catchments of the Haihe River basin and the Weishan experiment site in Shandong Province of China, this study has found variations in the Priestley-Taylor parameter α (e.g. increase in values with increase in the amount of precipitation on annual scale, seasonal fluctuation noted to be at a maximum during winter and at a minimum during summer, and increased values in the forenoon and decreased values in the afternoon on an hourly scale). This paper explains that the in- ter-annual variation in α is due to the negative feedback of atmosphere in response to changes in ac- tual increase in evapotranspiration, which is weakened because the atmosphere system is open. The parameter α undergoes a seasonal fluctuation brought about by seasonal changes in advection be- tween continent and ocean; α likewise undergoes a daily variation as a result of atmospheric hysteresis in response to the changes in land surface energy.
