Estimation Standard And Seeded Pan Evaporation Using Modelling Approach

Evaporation is an important meteorological variable that has also a great impact on water management. In this study, FAO-56 Penman-Monteith equation (FAO56-PM), multiple stepwise regression (MLR) and Kohonen self-organizing map (K-SOM) techniques were used for the estimation of daily pan evaporation (Ep) in three treatments, where C was the standard class A pan with top water, S was A pan with sediment covered bottom, and SM was class A pan containing submerged macrophytes (Myriophyllum sipctatum., Potamogeton perfoliatus, and Najas marina), in an six-season experiment. The modelling approach included six measured meteorological variables; daily mean air temperatures (Ta), maximum and minimum air temperatures, global radiation (Rs), relative humidity (RH), and wind speed (u) in the 2015–2020 growing seasons (from June to September), at Keszthely, Hungary. Average Ep varied from 0.6 to 6.9 mm d−1 for C, 0.7 to 7.9 mm d−1 for S, whereas from 0.9 to 8.2 mm d−1 for SM during the growing seasons studied. Correlation analysis and K-SOM visual representation revealed that Ta and Rs had stronger positive correlation, while RH had a negative correlation with the Ep of C, S and SM. Performances of the different models were compared using statistical indices, which included the root mean square error (RMSE), mean absolute error (MAE), scatter index (SI) and Nash-Sutcliffe efficiency (NSE). The results showed that the MLR method provided close compliance with the observed pan evaporation values, but the K-SOM method gave better estimates than the other methods. Overall, K-SOM has high accuracy and huge potential for Ep estimation for water bodies where freshwater submerged macrophytes are present.

Comparison of aerobic rice cultivation using drip systems with conventional flooding

In this study, yield and water productivity response of rice to various irrigation levels applied with subsurface and surface drip systems in 2019 and 2020 in the Mediterranean Region of Turkey was evaluated in comparison with conventional flooding (CF). The treatments consisted of two irrigation methods namely surface drip (DI) and subsurface drip systems (SDI), three irrigation levels designated as plant pan coefficients (I1.00: Evaporation from Class A pan (Ep) × 1.00; I1.25: Ep × 1.25 and I1.50: Ep × 1.50) and CF as control. The effects of drip systems and coefficients on yield and yield components were statistically significant (P < 0.01). DI produced higher yield than SDI. CF produced significantly greater yield than both DI and SDI systems. With two drip systems, average water savings of 60.5% in I1.00, 54.5% in I1.25 and 49% in I1.50 were achieved as compared to CF. However, yield reductions of 15% in I1.50, 20% in I1.25, 29% in I1.00 were observed for DI; corresponding values for SDI were 20, 28 and 44%, respectively. Drip irrigation in aerobic rice production system had almost twice the water productivity based on total irrigation water applied (WPI) or total water input (irrigation + rainfall) (WPI+P) compared with CF. During the study years, the highest WPI and WPI+P values were found in DI-I1.00 (0.81–0.73 kg/m3) and (0.85 and 0.74 kg/m3), respectively. In conclusion, DI-I1.50 treatment is recommended for sustainable aerobic rice production since DI-I1.50 resulted in water saving of 49% but yield decrease of 15% as compared to CF.

Reference evapotranspiration estimation by different methods for the sucroenergy sector of Colombia

ABSTRACT In the Colombian Sugarcane Research Center CENICAÑA, efficient use of water is always performed based on estimating reference evapotranspiration. In this method, class A pans have been used to estimate the reference evapotranspiration, which provides a more precise estimate of this important variable for water resource management. The objective of this study was to evaluate different reference evapotranspiration methods for the region of influence of the climatological station of the CENICAÑA experimental station. The class A pan method traditionally used in CENICAÑA was compared with and the Penman-Monteith FAO 56 standard method. The historical series used was from January 1, 1994, to December 31, 2014. The climatic variables were the maximum, mean, and minimum temperatures, the mean relative air humidity, solar radiation, and wind speed at 10 m. Willmott’s coefficients, the confidence index (c), and the root mean squared error were used in the performance evaluation. In the comparison with the Penman-Monteith FAO 56 method, all methods presented performance below the minimum requirement of (c) = 0.400. When all methods were compared with the method used in CENICAÑA (Class A pan), only the Penman-Monteith FAO 56 method showed performance classified as good (c = 0.689).

Annual Actual Evapotranspiration Estimation via GIS Models of Three Empirical Methods Employing Remotely Sensed Data for the Peloponnese, Greece, and Comparison with Annual MODIS ET and Pan Evaporation Measurements

Actual evapotranspiration (ETa) has been insufficiently investigated in Greece. This study aimed to estimate annual ETa by empirical methods (Turc, modified Turc, and Coutagne) for the Peloponnese, Greece, a Mediterranean testbed, between 2016–2019, four of the warmest years since the preindustrial era, and compare them to MODIS ET. Furthermore, measurements of annual pan evaporation (Epan) were performed for two Class A pan stations in the Peloponnese with different reliefs and conditions. The empirical methods and statistical formulae (RMSD, MB, and NMB) were developed as models in ArcMap. The outcomes of the Turc method resembled MODIS ET ranges for all years, followed by those of Coutagne. The estimates by the modified Turc method were almost identical to MODIS ET. Therefore, the modified Turc method can be used as an alternative to MODIS ET (and vice versa) for the Peloponnese for 2016–2019. Moreover, the Epan at Patras University station (semiurban, low elevation) exhibited an upward trend resembling the trends of the empirical methods over the study years, whereas the Epan at Ladonas station (higher elevation, lakeside) required investigation on a monthly time scale. Additionally, the gradual decrease of pan-water icing at Ladonas in December (from 20 d in 2016 to 0 d in 2019) could imply an undergoing decrease in snowpack storage retention across the mountains of the Peloponnese.

Effects of irrigation intervals and irrigation levels on oil content and fatty acid composition of peanut cultivars

Oil content and fatty acid composition are the most significant quality criteria of peanuts (Arachis hypogaea L.), and these parameters is greatly influenced by irrigation and fertilization practices. A study was conducted to investigate the effects of irrigation intervals and irrigation levels on oil content and fatty acid composition of peanuts, under sandy soil conditions in two consecutive years, using ‘Halisbey’, ‘NC-7’, and ‘Sultan’ peanut cultivars, commonly grown in Turkey. Irrigation levels were arranged based on total evaporation from Class-A pan, and irrigations were applied through drip lines. Irrigation intervals were set as two and four days, and irrigation levels were set as 50% (I50), 75% (I75), 100% (I100) and 125% (I125) of Class-A pan evaporations. Oil content, unsaturated fatty acids (oleic and linoleic acids), and saturated fatty acids (palmitic, myristic, arachidic, behenic and lignoceric acids) were determined. For oil content, treatments were identified as the most appropriate irrigation for a two-day irrigation interval of all cultivars, I100 for four-day irrigation interval of ‘Halisbey’ and ‘Sultan’ cultivars and I75 for four-day irrigation interval of ‘NC-7’ cultivar. Oleic, linoleic, and palmitic acids were the major fatty acids of peanuts. Cultivars exhibited different variations in these fatty acids based on irrigation intervals and irrigation levels. In general, oleic acid contents decreased, but linoleic and palmitic acid contents increased with increasing irrigation levels. The greatest oleic acid contents were obtained from two and four-day irrigation intervals of I50 treatments in ‘Halisbey’ and ‘NC-7’ cultivars and from two and four-day irrigation intervals of I75 treatments of the second year in ‘Sultan’ cultivar. Present findings revealed that for quality peanut production, both irrigation intervals and irrigation levels should be taken into consideration.

Measurement and Estimation of Annual Variability of Water Loss at Njuwa Lake Using Class ‘A’ Pan Evaporation Method

Aim: To measure and estimate the annual variability of water loss at Njuwa Lake using Class ‘A’ Pan Evaporation Method. Place and Duration of Study: Njuwa Lake in Yola South LGA, Adamawa State Nigeria between November, 2019 and May, 2020. Methodology: Direct measurements of morphometric characteristics of the lake were adopted using simple bathymetric method. Evaporation rates data and other related weather variable for the periods of ten (2007-2016) years were obtained from Upper Benue River Basin Development Authority located near the lake where the volume of water in the lake and the annual water loss were estimated using FAO estimate of water requirement procedures. Results: The results revealed that Njuwa Lake has morphometric characteristics of 1, 325 m average length, 180m average width, average depth 3.4 m, 238, 500 m2 of surface area, 1,445 m shoreline length and 0.834 m shoreline development with an estimated water volume of 810, 900 m3 respectively. Similarly, highest Class ‘A’ Pan evaporation rates were found in the year 2011, 2007 and 2008 with the corresponding total annual values of 2688.06 mm, 2403.64 mm and 2389.63 mm having an estimated values of water lost from the lake of 641, 102.310 m3 (79.07%), 573, 268.140 m3(70.7%) and 569, 926.755 m3 (70.29 %) correspondingly. Conversely, the year 2013,2012 and 2014 were found with the lowest measured Pan evaporation rates (1585.00 mm, 1611.54 mm and 1663.27 mm) with an estimated water lost on the lake of about 378, 022.500 m3 (46.6 %), 384, 352.290 m3 (47.4 %) and 396, 689.895 m3 (48.9 %). Conclusion: The rate of water loss was through evaporation was estimated to be greater than the stored water in the Lake in most of the years under study which led to untimely drying of the lake thereby affecting the irrigation farming in the area. Valuable strategies of water use efficiency and irrigation scheduling for effective utilization of the limited stored water in the lake for sustainable food production should be therefore adopted. The research work, however, need further work to make a comparison between the class ‘A’ Pan method and other empirical models method to revalidate the reliability.