Comparison of different geostatistical methods for estimating Evapotranspiration in salt lake watershed
2009
Vafakhah, M., Member of Scientific Board, Watershed Management Department, Natural Resources Faculty, Tarbiat Modares University | Mohseni Saravi, M., Associate Professor, Natural Resources Faculty, TehranUniversity | Onagh, M., Associate Professor.NAtural Resources Faculty Gorgan Univrtsity
Regarding the value of potential evapotranspiration as an important factor in water resources studies and suitability techniques of geostatistical methods, the present study has been investigated. For this purpose, all stations existed in the Salt Lake watershed were considered, and 37 stations with data collection period longer than 15 years and suitable spatial distribution were selected for the analysis. Three methods of ordinary kriging, cokriging and moving average using inverse and linear distance with powers of 1 to 3 were then applied for analyzing annual and monthly evapotranspiration data by using GS+ geostatistical software. The results showed that all methods except moving average through linear application perform equally well owing to low mean absolute error and mean bias. The precise comparison of results also showed that the cokriging and weighing moving average through inverse distance with power of 2 are the best methods for the analysis of data belong to September and October, and June, respectively, while the kriging method is the best performed model for other months and annual evapotranspiration data. According to the results obtained through analysis of variogram model, spherical and exponential, and linear models are supposed as the best models for monthly and annual data analysis, respectively. The results of the analysis also showed that the optimal distance between meteorological stations is some 40 km in the study area.
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