Water productivity using SAFER - Simple Algorithm for Evapotranspiration Retrieving in watershed

Abstract

A B S T R A C TThe Cabeceira Comprida stream's watershed, located in Santa Fé do Sul, São Paulo state, has great environmental importance. It is essential for supplying water to the population and generating surpluses for sewage dilution. This study aimed to evaluate the annual performance of the components of water productivity from Landsat-8 images of 2015, using the Simple Algorithm for Evapotranspiration Retrieving (SAFER), calculating the actual evapotranspiration (ET a ), biomass (BIO) and water productivity (WP). The annual averages of ETa, BIO and WP were 1.03 mm day -1 , 36.04 kg ha -1 day -1 and 3.19 kg m -3 , respectively. The average annual values of ET a for land use and occupation were 1.40, 1.23, 1.05, 0.97 and 1.08 mm day -1 for the remaining forest (RF), invasive species (IS), pasture (Pa), annual crop (AC) and perennial crop (PC), respectively, with BIO of 57. 64, 46.10, 36.78, 32.69, 40.03 kg ha -1 day -1 for RF, IS, Pa, AC and PC, respectively, resulting in WP of 3.94, 3.59, 3.25, 3.09, 3.35 kg m -3 for RF, IS, Pa, AC and PC, respectively. The ETa, BIO and WP adjust to the seasonality of the region, and RF and IS stood out with the highest values.Produtividade da água estimada pelo SAFER -Simple Algorithm for Evapotranspiration Retrieving em bacia hidrográfica R E S U M OA Bacia Hidrográfica do Córrego Cabeceira Comprida localizada no município de Santa Fé do Sul-SP, tem grande importância ambiental, sendo imprescindível para o abastecimento de água à população e para gerar excedentes para a diluição do esgoto gerado. Assim, este trabalho avaliou o comportamento anual dos componentes da produtividade da água a partir de imagens do Landsat-8 do ano 2015, utilizando-se o 'Simple Algorithm for Evapotranspiration Retrieving' (SAFER), sendo calculadas a evapotranspiração atual (ET a ), a biomassa (BIO) e a produtividade da água (PA). As médias anuais da ETa, BIO e PA foram 1,03 mm dia -1 , 36,04 kg ha -1 dia -1 e 3,19 kg m -3 , respectivamente. As ETa médias anuais por uso e ocupação do solo foram 1,40, 1,23, 1,05, 0,97 e 1,08 mm dia -1 para mata remanescente (MR), espécies invasoras (EI), pastagem (Pa), cultura anual (CA) e cultura perene (CP), respectivamente, enquanto que as BIO apresentaram 57,64, 46,10, 36,78, 32,69, 40,03 kg ha -1 dia -1 para MR, EI, Pa, CA e CP, respectivamente, resultando em uma PA de 3,94, 3,59, 3,25, 3,09, 3, para MR, EI, Pa, CA e CP, respectivamente. As ET a , BIO e PA se ajustam à sazonalidade climática da região destacando-se a MR e as EI com os maiores valores.

Large-Scale Spatial Modeling of Crop Coefficient and Biomass Production in Agroecosystems in Southeast Brazil

“…Figure 6 shows the spatial distribution of the net radiation for each DOY and Table 2 presents the mean values and standard deviation for each DOY and relevant land use. Net radiation is strongly dependent on solar radiation (RG), and the capacity to differentiate between land uses through this variable is low, as already diagnosed by Teixeira et al [25,27]. However, there was a tendency for a higher radiation balance in the areas occupied by Eucalyptus and forest and lower values in pasture and sugarcane.…”

“…All the regression coefficients of the parameters in Figure 3 and equations below were determined in different areas of Brazil with digital images from different satellites, like Landsat [6,7,13,14,[23][24][25], RapidEye [26], and MODIS [9,27], with field measurements for calibration involving strong contrasting agroecosystems, and under different thermohydrological conditions throughout several years as semiarid areas [9,13,25], wetlands [27], tropical [23], and subtropical areas [6,7,14]. Most of the regressions performed from Landsat-8 were used in this work due to their similarity to the radiometric data on the visible (RGB) and near infrared (NIR) range of the Sentinel-2 satellite [22,28].…”

“…The application of this methodology for surface temperature retrieval provides 10-m resolution results, while the SEBAL requires the use of thermal bands, which in Sentinel-2, has a spatial resolution of 1 km. The net radiation was also evaluated in this work as an indicator of the energy supply to the soil [25]. It was decided that the residual method would be used to obtain the surface temperature to preserve the spatial resolution, since the thermal bands have a resolution of 1 km, which increases the uncertainty in the modeling [38].…”

“…BIO is directly related to the product harvested through the harvest index (HI), the percentage of biomass effectively harvested and transformed into the final product [6,14,[24][25][26][27], and the fraction of carbon in the biomass [25][26][27]. The HI depends on whether the property is mechanized or not, and economic and topographical factors [9].…”

“…The availability of freely moderate-to-high spatial resolution satellite imagery stimulated the use of remote sensing solutions in spatial modeling, especially after the launch of the Landsat-8 satellite in 2013 [22]. While Landsat-8 imagery (at 30 m spatial resolution) has been widely used for ET mapping [6,7,[23][24][25], other remote sensing imagery, like RapidEye [26] and MODIS [27], with higher and lower spatial resolution than the Landsat-8, respectively, began to be used successfully. A new option is the Sentinel-2 satellite, launched in June 2015, which provides multi-spectral images in 13 bands at different spatial resolutions, including three visible (RGB) and one near infrared (NIR) bands at 10 m spatial resolution, six red-edge and shortwave infrared (SWIR) bands at 20 m, and three atmospheric correction bands at 60 m [28] acquired at a swath width of 290 km and a five-day temporal resolution.…”