Controlling factors of ‘Caatinga’ and sugarcane evapotranspiration in the Sub-middle São Francisco Valley

Carvalho, Herica Fernanda de Sousa; Moura, M. S. B. de; Silva, Thieres George Freire da

doi:10.1590/1807-1929/agriambi.v22n4p225-230

Cited by 4 publications

(2 citation statements)

References 13 publications

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“…This improved performance can be explained because soil moisture is incorporated in the STEEP algorithm. In semi-arid regions and particularly in the SDTF, besides the availability of energy, evapotranspiration is highly dependent on the soil-water availability (Lima et al, 2012;Carvalho et al, 2018;Mutti et al, 2019;Paloschi et al, 2020). In rainy months, low daily ET rates are often observed due to the reduced levels of incoming radiation caused by high cloud cover (Mutti et al, 2019;Paloschi et al, 2020).…”

Section: Resultsmentioning

confidence: 99%

STEEP: a remotely-sensed energy balance model for evapotranspiration estimation in seasonally dry tropical forests

Bezerra¹,

Cunha²,

Falente³

et al. 2023

Preprint

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Improvement of evapotranspiration (ET) estimates using remote sensing (RS) products based on multispectral and thermal sensors has been a breakthrough in hydrological research. In large-scale applications, methods that use the approach of RS-based surface energy balance (SEB) models often rely on oversimplifications of the aerodynamic resistances. The use of these SEB models for Seasonally Dry Tropical Forests (SDTF) has been challenging due to incompatibilities between the assumptions underlying those models and the specificities of this environment, such as the highly contrasting phenological phases or ET is mainly controlled by soil–water availability. We developed a RS-based SEB model from a one-source bulk transfer equation, called STEEP. Our model uses the Plant Area Index to represent the woody structure of the plants in calculating the moment roughness length. In the aerodynamic resistance for heat transfer, the parameter kB-1 was included, correcting it with RS soil moisture. Besides, the remaining λET in endmembers pixels was quantified using the Priestley-Taylor equation. We implemented the STEEP algorithm on the Google Earth Engine platform, using worldwide free data. Four sites with eddy covariance data located in the Caatinga, the largest SDTF in South America, in the Brazilian semiarid region, were used to evaluate the STEEP model. Our results show that STEEP based on the specific characteristics of the SDTF increased the accuracy of ET estimates without requiring any additional climatological information. This improvement is more pronounced during the dry season, which in general, ET for these SDTF is overestimated by traditional SEB models, as happened in our research with the SEBAL. The STEEP model had similar or superior behaviour and performance statistics relative to global ET products (MOD16 and PMLv2). This work contributes to an improved understanding of the drivers and modulators of the energy and water balances at local and regional scales in SDTF.

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Section: Resultsmentioning

confidence: 99%

STEEP: a remotely-sensed energy balance model for evapotranspiration estimation in seasonally dry tropical forests

Bezerra¹,

Cunha²,

Falente³

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

Section: Comparison Of Steep and Sebal Models Results With Observed (...mentioning

confidence: 99%

STEEP: A remotely-sensed energy balance model for evapotranspiration estimation in seasonally dry tropical forests

Bezerra

Cunha

Valente

et al. 2023

Agricultural and Forest Meteorology

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Actual and standard crop coefficients for semi-natural and planted grasslands and grasses: a review aimed at supporting water management to improve production and ecosystem services

et al. 2023

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Natural and planted grasslands play a very important role in agriculture as source of various ecosystem services, including carbon sequestration and biodiversity, and are responsible for a large fraction of agricultural water use in rainfed and irrigated fields. It is, therefore, relevant to precisely know their water use and vegetation requirements with consideration of relevant climate, from extremely cold, dry, with long winter seasons, to tropical humid and hot climates, thus with a large variability of vegetation. Semi-natural grasslands are basically used for grazing and mainly refer to highland pastures and meadows, steppes, savannas, pampas, and mixed forest systems. The FAO method to compute crop (vegetation) evapotranspiration (ETc) through the product of a crop coefficient (Kc) by the reference evapotranspiration (ETo) is adopted. The selected papers were those where actual ETc (ETc act) was derived from field observations and ETo was computed with the FAO56 definition, or with another method that could be referred to the former. Field derived ETc act methods included soil water balance, Bowen ratio and eddy covariance measurements, as well as remote sensing vegetation indices or surface energy balance models, thus reviewed Kc act (ETc act/ETo) values were obtained from field data. These Kc act refer to initial, mid-season and end season (Kc act ini, Kc act mid, Kc act end) when reported values were daily or monthly; otherwise, only average values (Kc act avg) were collected. For cases relative to cold or freezing winters, data refer to the warm season only. For grasses cut for hay, Kc act ini, Kc act mid, and Kc act end refer to a cut cycle. Kc act values rarely exceeded 1.25, thus indicating that field measurements reported did respect the available energy for evaporation. Overall, Kc act mid for semi-natural grasslands in cold climates were lower than those in hot climates except when available water was high, with Kc act mid for meadows and mountain pastures generally high. Steppes have Kc act mid values lower than savannas. Grasses commonly planted for hay and for landscape generally showed high Kc act mid values, while a larger variability was observed with grasses for grazing. The collected Kc act values were used to define standard Kc values for all grassland and grasses. Nevertheless, the tabulated Kc act are indicative values of Kc to be used for actual water management purposes and/or irrigation scheduling of planted grasslands. It is expected that a better knowledge of the standard and/or indicative Kc values for a wide variety of grasslands and grasses will support better management aimed to improve grass productivity and ecosystem services, including biodiversity and carbon sequestration.

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Controlling factors of ‘Caatinga’ and sugarcane evapotranspiration in the Sub-middle São Francisco Valley

Cited by 4 publications

References 13 publications

STEEP: a remotely-sensed energy balance model for evapotranspiration estimation in seasonally dry tropical forests

STEEP: a remotely-sensed energy balance model for evapotranspiration estimation in seasonally dry tropical forests

STEEP: A remotely-sensed energy balance model for evapotranspiration estimation in seasonally dry tropical forests

Actual and standard crop coefficients for semi-natural and planted grasslands and grasses: a review aimed at supporting water management to improve production and ecosystem services

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