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

Abstract

The 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 (ETa), biomass (BIO) and water productivity (WP). The annual averages of ETa, BIO and WP were 1.03 mm d-1, 36.04 kg ha-1 d-1 and 3.19 kg m-3, respectively. The average annual values of ETa for land use and occupation were 1.40, 1.23, 1.05, 0.97 and 1.08 mm d-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 d-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.

Full text

Revista Brasileira de Engenharia Agrícola e Ambiental
Campina Grande, PB, UAEA/UFCG – http://www.agriambi.com.br
ISSN 1807-1929
v.21, n.8, p.524-529, 2017
Water productivity using SAFER - Simple Algorithm
for Evapotranspiration Retrieving in watershed
Daniel N. Coaguila1, Fernando B. T. Hernandez1, Antônio H. de C. Teixeira2,
Renato A. M. Franco1 & Janice F. Leivas2
DOI: http://dx.doi.org/10.1590/1807-1929/agriambi.v21n8p524-529
A B S T R A C T
e 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. is 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 (ETa), biomass (BIO) and water productivity (WP). e 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. e average annual values of ETa 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. e 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 hidrográca
R E S U M O
A Bacia Hidrográca 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 (ETa), 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, 3,35 kg m-3 para MR,
EI, Pa, CA e CP, respectivamente. As ETa, BIO e PA se ajustam à sazonalidade climática da
região destacando-se a MR e as EI com os maiores valores.
Key words:
biomass
evapotranspiration
remote sensing
Typha
Palavras-chave:
biomassa
evapotranspiração
sensoriamento remoto
Typha
1 Universidade Estadual Paulista/Faculdade de Engenharia de Ilha Solteira/Departamento de Fitossanidade, Engenharia Rural e Solos. Ilha Solteira, SP.
E-mail: tuheraldo@gmail.com (Corresponding author); thtang@agr.feis.unesp.br; bioramfranco@yahoo.com.br
2 Embrapa Monitoramento por Satélite. Campinas, SP. E-mail: heriberto.teixeira@embrapa.br; janice.leivas@embrapa.br
Ref. 162-2016 – Received 3 Oct, 2016 • Accepted 3 Mar, 2017 • Published 29 Jun, 2017

525Water productivity using SAFER - Simple Algorithm for Evapotranspiration Retrieving in watershed
R. Bras. Eng. Agríc. Ambiental, v.21, n.8, p.524-529, 2017.
I
Water management must promote its multiple use, such
as the supply of cities, dilution of euents, animal watering,
among others (Machado et al., 2011). Measuring water
consumption in agriculture (evapotranspiration), in a spatial-
temporal scale for watershed, improves the management of
water resources. In a watershed, there is interaction between
natural, social, biotic and abiotic factors, involved in a network
of relationships (Machado et al., 2011), which are in dynamic
equilibrium (Erol & Randhir, 2012), when not disturbed.
e Northwest region of São Paulo has predominance of
livestock farming (IBGE, 2016), the highest evapotranspiration
rates of the state, with water decit for up to eight months in the
year (Santos et al., 2010) and also frequent dry spells that pose
risk to the performance of agriculture (Hernandez et al., 2003).
In watersheds, with the conflicting use of water, it is
important to determine crop evapotranspiration (Bezerra
et al., 2012), biomass and water productivity, which are
dicult to be estimated in large scale (Su et al., 2009). Remote
sensing techniques allow the generation of temporal series for
agricultural planning (Bastiaanssen, 2000), management and
evaluation of the water resources.
e Simple Algorithm for Evapotranspiration Retrieving
(SAFER), which presents itself as a tool for the management of
water resources, is based on the modeling of the ETa/ET0 ratio
(Teixeira et al., 2015a) and has been adjusted to the Northwest
region of São Paulo (Hernandez et al., 2014) and calibrated for
other regions (Teixeira et al., 2015c).
e present study aimed to evaluate actual evapotrans-
piration, biomass and water productivity through the SAFER
model using Landsat-8 images, in the Cabeceira Comprida
stream’s watershed, in Santa Fé do Sul, SP.
M  M
The studied watershed is located in the municipality
of Santa Fé do Sul, Northwestern São Paulo state, at the
geographic coordinates of 0º 55' 5" W and 20º 10' 9" S, with 380
m of altitude (Figure 1A), and its area is occupied by 143, 149,
1005, 1271 and 454 hectares of remaining forest (RF), invasive
species (IS), pasture (Pa), annual crop (AC) and perennial
crop (PC), respectively, under humid tropical climate with dry
winter, Aw, according to Köppen’s classication.
e utilized data of the Northwestern São Paulo State
Weather Network (http://clima.feis.unesp.br, Figure 1A)
are composed of global radiation (RG, MJ m-2 day-1),
reference evapotranspiration (ET0, mm day-1) and mean daily
temperature (Ta, °C), spatialized through the inverse distance
weighting (IDW).
e images were obtained from the USGS website (http://
earthexplorer.usgs.gov), of the Landsat 8 platform (OLI and
TIRS), orbit 22 and point 74, of the year 2015, with the rst
image in January 2015, following the sequential day of the
year (SDY) with temporal scale of 16 days. Cloud-free images
were used and processed in the soware ArcMap™ 10.0 of the
ESRI in the Model Builder mode. In case of clouds, the series
was lled with the mean of the images available close to the
lacking date in a set with grids of Ta, RG and ET0 of the specic
lacking dates.
Radiometric correction (radiance and reflectance) of
the images was performed according to the methodology of
Teixeira et al. (2015b) and the broadband planetary albedo
on top of the atmosphere (αTOA) was calculated using the
methodology of Teixeira et al. (2015a), while the brightness
temperature of the sensor (Tbri) was obtained through the
methodology of Teixeira et al. (2015b). The normalized
dierence vegetation index (NDVI) was calculated through
the ratio of the dierence between the planetary reectivities
of the near infrared (ρnir) and red (ρred) and their sum.
e data of αTOA and Tbri were atmospherically corrected to
obtain the values of albedo (α0) and surface temperature (T0,
K), according to Teixeira et al. (2015b):
Figure 1. Land use and occupation in the Cabeceira Comprida stream’s watershed (A), Means (every 16 days) of global
radiation - RG and totals of pluviometric precipitation - P and reference evapotranspiration - ET0, during the year 2015 (B)
0 TOA
0.61 0.08α = ⋅α +
0 bri
T 1.07 T 20.17= ⋅−
(1)
(2)

526 Daniel N. Coaguila et al.
R. Bras. Eng. Agríc. Ambiental, v.21, n.8, p.524-529, 2017.
e ratio between actual evapotranspiration and reference
evapotranspiration (ETa/ET0)SAFER was calculated according to
Eq. 3 (Hernandez et al., 2014; Teixeira, 2010; Teixeira et al.,
2015c):
Biomass (BIO, kg ha-1 day-1) is the dry matter production
per area unit over time and was calculated using the radiation
model of Monteith (Teixeira et al., 2015b):
a0
00
SAFER
ET T
exp 1.0 0.008
ET NDVI

  
= +

  
α

  

Actual evapotranspiration (ETa, mm day-1) was obtained
according to Teixeira et al. (2015c):
a
a0
0
SAFER
ET
ET ET ET

=

e concept of equilibrium evapotranspiration (Raupach,
2001) was used in Eq. 4, when NDVI < 0, transforming the
energy units to mm day-1 (Teixeira et al., 2015c):
( )
n
RG
E
∆−
λ= ∆+γ
where:
Δ - slope of the water vapor saturation curve, kPa °C-1;
Rn - net radiation, MJ m-2 day-1;
G - heat ow in the soil, MJ m-2 day-1; and,
γ - psychrometric constant, kPa °C-1.
Net radiation (Rn) was obtained by the Slob’s equation
(Bruin & Stricker, 2000; Teixeira et al., 2015a):
( )
n 24 G L sw
R 1 Ra= −α − τ
Figure 2. Mean values of actual evapotranspiration - ETa (A), biomass - BIO (B) and water productivity - WP (C) in the
Cabeceira Comprida stream’s watershed, calculated using the SAFER model
where:
α24 - surface albedo of 24 h;
aL - regression coecient of the net longwave radiation;
and,
τsw - atmospheric transmissivity (Bruin & Stricker, 2000).
Heat flow in the soil (G) was estimated through its
relationship with the net radiation (Rn) (Teixeira et al., 2015c):
( )
0
n
G3.98 exp 31.89
R= ⋅ − ⋅α
max f
BIO E APAR 0.864=ε⋅
where:
εmax - maximum efficiency in the use of radiation
(Bastiaanssen & Ali, 2003);
Ef - Evaporative fraction (Teixeira et al., 2015b); and,
APAR - absorbed photosynthetically active radiation (W
m-2).
APAR was directly approximated as a fraction of the
photosynthetically active radiation (PAR) depending on the
NDVI and PAR, as a fraction of the RG (Teixeira et al., 2015a):
( ) ( )
G
APAR 1.26 NDVI 0.16 0.44 R=⋅ −⋅⋅
Water productivity (WP, kg m-3) refers to the amount of
biomass that can be produced per 1 m3 of water and provides
information on the water use eciency by plants (Teixeira et
al., 2015b), calculated as:
a
BIO
PA ET
=
R  D
The results of highest and lowest mean ETa in the
watershed were 1.87 and 0.23 mm day-1 on the SDY 15 and
255, respectively (Figure 2A), corresponding to the climatic
behavior of the region, rainy summer and dry winter. e
evapotranspiration amplitude of 1.64 mm day-1 (dierence
between the highest and lowest ETa), despite the predominance
of annual crops, conrms the high heterogeneity of the system
regarding land use and dependence on the rainfall regime for
the economic development of the watershed, and results close
to the values in the dry season were reported in Northwestern
São Paulo by Coaguila et al. (2015).
e typical expected behavior of RG is an increasing curve
from August on, with peak in the summer, but high RG values
(> 20 MJ m-2 d-1) were also recorded in the spring and summer,
while the high number of rainy days in November (16) and
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)

527Water productivity using SAFER - Simple Algorithm for Evapotranspiration Retrieving in watershed
R. Bras. Eng. Agríc. Ambiental, v.21, n.8, p.524-529, 2017.
December (18) resulted in means lower than expected for RG
and, consequently, for ETa (Figures 1B and 2A).
On the other hand, the rainfalls resulted in storage and
availability of water to plants and these rainfalls above 50
mm every 16 days were recorded in all seasons of the year
(Figure 1B), related in general to the greater volumes of ETa
in the summer and smaller in the winter, when RG availability
is sucient to increase the ETa volumes. However, it does
not occur due to the water decit characteristic of the season
(Santos et al., 2010; IBGE, 2016), except the area occupied by
the IS - in the riparian zone - since rainfall and RG control the
ETa, as reported by Scott et al. (2000), requiring both climatic
variables to occur concomitantly (Figure 2A).
The IS (Typh a sp. as dominant) in the humid period
evapotranspired 82-89% (in relation to the RF) and 91-97% in
the dry season, consuming the same water that could support
the RF, agricultural activities or the population of Santa Fé do
Sul, because the priority in water use culminates in human
consumption and animal watering (Machado et al., 2011).
The ISs, predominantly represented by Typha sp., are
aggregated as a species that indicates degraded environments
and do not oer any benet to the local ecosystems (Linz &
Homan, 2011), being a consequence of erosion processes and
thalweg silting. However, they fulll their hydrological function
and, for being large water consumers, compete with the storage
necessary in the dams that must supply the population of
Santa Fé do Sul. In addition, they produce surpluses to dilute
the euent of the Sewage Treatment Station disposed in the
Mula stream, into which the Cabeceira Comprida stream ows.
Evapotranspiration values of 1.2 mm day-1 were described
by Anda et al. (2015) and Coaguila et al. (2015), corroborating
the values of mean annual ETa of the IS of 1.23 mm day-1 in the
studied watershed (Table 1).
e ETa of Pa, AC and PC was equal to 61-80, 55-76 and 71-
82%, respectively, in relation to RF, in the dry season, atypically
increasing the values due to the unexpected rainfall and that,
along the dry period, maintained its typical behavior, with
increasing water decit and decrease of ETa, thus entering the
spring with water decit in the soil and values of 59-78, 51-74
and 70-76% for Pa, AC and PC, respectively, in relation to the
mean of the RF. In the rainy period, values of 72-80, 68-72 and
76-79% were reached by Pa, AC and PC, respectively, favored
by the rainfall and high RG values characteristic of the period
(Figure 1B).
It should be pointed out the water availability in the soil
directly inuenced the amount of energy used, when available
in the evapotranspiration processes; therefore, the mean
volume of evapotranspired water in the Cabeceira Comprida
stream’s watershed in 2015 was 33,020 m3 day-1, formed by
5.5% from IS, 6.1% from RF, 32.0% from Pa, 38.0% from AC
and 14.8% from PC, leaving 3.6% for the other uses. us, the
water used by IS corresponds to the consumption of 30% of
the population of Santa Fé do Sul and, considering a mean
water consumption of 189 L day-1 per person and the 31,348
inhabitants estimated for 2015 (IBGE, 2016; SNIS, 2016), the
municipality consumes 5,925 m3 d-1.
e highest and lowest mean BIO are distributed in the
summer (64.21 kg ha-1 day-1, SDY 15) and winter (5.50 kg ha-1
day-1, SDY 255), respectively (Figure 2B) and correspond to
the climatic seasonality and high heterogeneity of the region
(Santos et al., 2010; IBGE, 2016), a prove of that is the BIO
annual amplitude of 58.71 kg ha-1 day-1. Mean values of 9.17
and 10.98 kg ha-1 day-1 were recorded during the dry period
in the years 2013 and 2014 in the Mula stream’s watershed, by
Coaguila et al. (2015), also in Santa Fé do Sul.
BIO is dependent on RG (Teixeira et al., 2015b), local
vegetation and water available in the soil (Scott et al., 2000),
and its value decreased from June to August, due to the dry
conditions and low levels of RG (Figure 1B), which is related
to the water stress in the soil and weather conditions of the
IS - Invasive species; RF - Remaining forest; Pa - Pasture; AC - Annual crop; PC - Perennial crop; SDY - Sequential day of the year
Date
2015 SDY ETa(mm day-1) BIO (kg ha-1 day-1) WP (kg m-3)
IS RF Pa AC PC IS RF Pa AC PC IS RF Pa AC PC
Jan 15 15 2.25 2.56 1.94 1.75 1.94 84.95 104.69 66.88 57.40 69.91 3.71 4.01 3.31 3.11 3.39
Jan 31 31 2.13 2.41 1.74 1.68 1.89 81.41 98.52 59.18 55.82 70.93 3.72 3.97 3.22 3.13 3.43
Feb 16 47 1.60 1.81 1.39 1.29 1.41 56.53 69.27 45.04 39.87 48.07 3.47 3.76 3.13 2.98 3.21
Mar 04 63 1.90 2.17 1.70 1.55 1.68 73.24 90.47 60.87 52.86 62.29 3.78 4.11 3.48 3.29 3.50
Mar 20 79 1.32 1.51 1.20 1.09 1.17 46.62 57.81 40.18 34.34 39.85 3.45 3.79 3.24 3.03 3.20
Apr 05 95 1.16 1.33 1.07 0.97 1.04 46.34 57.50 40.43 35.05 40.27 3.91 4.28 3.69 3.48 3.65
Apr 21 111 1.42 1.62 1.31 1.21 1.28 65.81 81.18 58.11 51.06 58.19 4.53 4.96 4.31 4.08 4.25
May 07 127 1.33 1.49 1.22 1.15 1.21 53.79 65.83 48.14 43.78 49.33 3.98 4.35 3.81 3.65 3. 76
May 23 143 0.89 1.00 0.83 0.78 0.83 38.01 46.65 34.51 31.34 35.57 4.17 4.57 4.01 3.85 4. 01
Jun 08 159 1.04 1.17 0.98 0.92 0.99 46.16 56.79 42.65 38.87 44.78 4.34 4.76 4.19 4.03 4.24
Jun 24 175 0.93 1.05 0.84 0.80 0.86 36.24 44.99 31.04 28.58 33.13 3.79 4.18 3.54 3.41 3. 62
Jul 10 191 1.23 1.38 1.06 1.01 1.10 50.54 62.71 40.34 37.49 44.40 4.01 4.42 3.61 3.48 3.72
Jul 26 207 0.81 0.89 0.64 0.60 0.68 28.93 34.47 20.03 18.49 23.11 3.47 3.77 2.96 2.85 3.14
Aug 11 223 0.87 0.90 0.58 0.54 0.65 30.22 33.65 17.00 15.46 21.54 3.35 3.55 2.72 2.61 2.95
Aug 27 239 0.45 0.49 0.31 0.28 0.36 13.01 15.37 7.51 6.59 9.57 2.75 2.97 2.26 2.15 2.46
Sep 12 255 0.33 0.37 0.23 0.20 0.27 8.86 11.13 5.24 4.52 6.87 2.61 2.86 2.16 2.05 2.37
Sep 28 271 0.42 0.50 0.29 0.26 0.35 12.74 16.95 7.79 6.59 10.50 2.94 3.27 2.47 2.32 2.71
Oct 14 287 1.25 1.53 0.89 0.78 1.08 45.86 63.86 29.19 23.99 40.27 3.56 4.01 3.04 2.84 3.34
Oct 30 303 1.45 1.74 1.16 1.05 1.28 50.15 67.65 36.42 31.16 43.89 3.37 3.78 2.99 2.82 3.18
Nov 15 319 1.01 1.20 0.84 0.77 0.90 33.03 43.94 25.13 22.01 29.04 3.20 3.58 2.89 2.74 3.03
Dec 01 335 1.46 1.73 1.26 1.17 1.32 51.14 67.02 40.85 36.24 45.12 3.41 3.80 3.12 2.98 3.23
Dec 17 351 1.71 1.99 1.55 1.46 1.55 60.70 77.61 52.60 47.72 54.07 3.47 3.84 3.28 3.15 3.31
Mean 1.23 1.40 1.05 0.97 1.08 46.10 57.64 36.78 32.69 40.03 3.59 3.94 3.25 3.09 3.35
Table 1. Actual evapotranspiration (ETa), biomass (BIO) and water productivity (WP), per use and occupation of the
soil, in the Cabeceira Comprida stream’s watershed

528 Daniel N. Coaguila et al.
R. Bras. Eng. Agríc. Ambiental, v.21, n.8, p.524-529, 2017.
region (Santos et al., 2010), resulting in lower production of
vegetal biomass (Li et al., 2011).
e highest means of BIO occurred on the SDY 15, with
84.95, 104.69, 66.88 and 57.24 kg ha-1 day-1 for IS, RF, Pa and
AC, respectively, and 70.93 kg ha-1 day-1 on SDY 31 for PC;
however, the lowest BIO means were 8.86, 11.13, 5.24, 4.52
and 6.87 kg ha-1 day-1 for IS, RF, Pa, AC and PC, respectively,
on SDY 255 (Table 1), both with highest and lowest BIO, in
the humid and dry seasons, respectively.
In the summer, with high values of RG and rainfall, the IS
produced 81-83% of BIO in relation to RF, while in the dry
period it remained in 80-84%, for occupying the riparian zone
(Bove, 2016), suering minimum water stress, representing
5.9% of the approximately 115,533 kg day-1 produced by the
watershed.
Land uses and occupations of the Pa, AC and PC, in relation
to RF, showed BIO of 64-75, 55-68 and 69-72%, respectively,
during the period of rainfalls and highest RG of the year, which
favored BIO production, while in the dry period, with lower
values of RG, there were lower values of BIO, 47-69, 41-64 and
62-74% for Pa, AC and PC (Figure 1B, Table 1), resulting in the
mean of approximately 32% for Pa, 36% for AC and 16% for PC
of the 115,533 kg day-1, on average, produced by the watershed.
The highest and lowest mean of WP occurred in the
autumn (4.16 kg m-3, SDY 111) and winter (2.17 kg m-3, SDY
255) (Figure 2C), similar to ETa and BIO, distributed in the
rainy and dry periods with annual amplitude of 1.99 kg m-3,
and again conrm the high heterogeneity of the watershed,
corroborating Coaguila et al. (2015), who observed mean
WP values of 1.73-3.75 kg m-3 in the Mula stream’s watershed.
e high WP of the IS (Table 1) is explained by the fact
that these species benet from the continuous ow of water,
since they are installed in the silted riparian zone (Bove, 2016),
with adequate conditions for proliferation, and varied from 89
to 94% along the year, in relation to RF, showing the lowest
variations of the year, along with the PC but, dierent from the
IS, benet from the deep root system, which allows the access
to the water in the soil prole.
Table 1 highlights, per land use and occupation, the highest
mean WP on SDY 111 (autumn) with 4.53, 4.96, 4.31, 4.08
and 4.25 kg m-3 for IS, RF, Pa, AC and PC, respectively, and
the lowest WP on SDY 255 (winter) with 2.61, 2.86, 2.16, 2.05
and 2.37 kg m-3 for IS, RF, Pa, AC and PC, respectively. Values
close to those of the dry and humid periods were reported by
Coaguila et al. (2015) and Teixeira et al. (2015a).
Pa, AC and PC showed values of 81-88, 78-85 and 85-89%
in relation to the RF, respectively, in the rainy period, whose
conditions were favorable to vegetation development and WP.
In the dry period, Pa, AC and PC showed values of 76-85, 71-
82 and 83-87%, respectively.
C
1. e temporal variability of ETa, BIO and WP adjusts to
the climatic seasonality of the region, especially to the rainfall
and radiation available in the studied area.
2. e highest ETa, BIO and WP, in a decreasing order, are
relative the use and occupation by remaining forest, invasive
species, perennial crops, pasture and annual crops.
3. e invasive species present in the riparian zone suer
minimum water stress during the dry period and have direct
impact on the water supply in the watershed.
4. e model SAFER - Simple Algorithm for Evapotrans-
piration Retrieving - proved to be adequate to quantify water
productivity components by dierent land uses in a watershed.
A
To the PAEDEx of UNESP and AUIP/Capes (Process
2012), FAPESP (Process 2.009/52.467-4) and CNPq (Process
404.229/2013-1).
L C
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