Effects o wind data temporal resolution on wind erosion prediction with RWEQ.

PANEBIANCO J. E., BUSCHIAZZO D. E.

Santa Rosa, La Pampa

Congreso; international Conference on Aeolian Research; 2010

INCITAP

In wind erosion modelling, wind energy is the driving force of the erosion process. Stand alone versions of wind erosion models are simplified versions used for discrete, short period simulation. The full and more complex versions are used for continuous simulation along fixed time steps. In any wind erosion model, wind speed records are used to simulate the wind transport capacity. Available wind erosion models were developed using high resolution wind speed data. However, in many regions of the world high resolution wind records are scarce. In order to evaluate the effects of wind data resolution in wind erosion assessment with RWEQ, wind energy values and Weibull distribution function parameters were calculated using different temporal resolution wind speed records. Soil losses were measured during 82 wind erosion events in an experimental plot in semiarid central Argentina. A weather file for RWEQ/97 was developed for the study site. RWEQ discrete and continuous version performances were evaluated by comparing simulated with measured soil losses using the Pearson correlation coefficient (r), the Nash Sutcliffe index (NS), and the mean deviation (MD). Using RWEQ discrete version, the wind energy was reduced by 21% when using hourly wind speeds instead o five minute averages, and the total simulated soil loss was reduced by 44%. This reduced erosion value still represented 75.5% of the measured soil loss. The model efficiency for simulating discrete wind erosion events was relatively good (r=0.67; NS= 0.41; MD =122 kg/ha), and it was not significantly affected by wind speed data resolution. RWEQ/97 continuous version loaded with the Weibull function parameters calculated using hourly wind speeds, simulated zero erosion even under very low roughness and vegetative cover conditions. Increasing the monthly Weibull scale parameters by 21% improved the monthly erosion rates, but the model efficiency remained low. A similar result was obtained when increasing scale parameters by 50% (r= 0.24; NS= -0.01). Wind speed records with lower temporal resolution reduced the frequency of occurrence of higher wind speeds, reducing wind energies and Weibull parameters.