Topographic effects on solar radiation distribution in mountainous watersheds and their influence on reference evapotranspiration estimates at watershed scale
Metadatos
Mostrar el registro completo del ítemFecha
2010-12-10Patrocinador
Andalusian Water Institute in the project Pilot study for the integral management of the Guadalfeo river watershed and by the Regional Innovation, Science and Enterprise Ministry grant for PhD training in Andalusian Universities and Research CentersResumen
Distributed energy and water balance models require time-series surfaces of the climatological variables involved
in hydrological processes. Among them, solar radiation constitutes a key variable to the circulation of water
in the atmosphere. Most of the hydrological GIS-based models apply simple interpolation techniques to data measured
at few weather stations disregarding topographic effects. Here, a topographic solar radiation algorithm has been
included for the generation of detailed time-series solar radiation surfaces using limited data and simple methods in
a mountainous watershed in southern Spain. The results show the major role of topography in local values and differences
between the topographic approximation and the direct interpolation to measured data (IDW) of up to +42% and
−1800% in the estimated daily values. Also, the comparison of the predicted values with experimental data proves the
usefulness of the algorithm for the estimation of spatially-distributed radiation values in a complex terrain, with a good
fit for daily values (R2 = 0.93) and the best fits under cloudless skies at hourly time steps. Finally, evapotranspiration
fields estimated through the ASCE-Penman-Monteith equation using both corrected and non-corrected radiation values
address the hydrologic importance of using topographically-corrected solar radiation fields as inputs to the equation over
uniform values with mean differences in the watershed of 61 mm/year and 142 mm/year of standard deviation. High
speed computations in a 1300 km2 watershed in the south of Spain with up to a one-hour time scale in 30×30m2 cells
can be easily carried out on a desktop PC.