Hargreaves Method Research Articles

Application of Artificial Neural Networks to Project Reference Evapotranspiration Under Climate Change Scenarios

Evapotranspiration is sensitive to climate change. The main objective of this study was to examine the response of reference evapotranspiration (ET0) under various climate change scenarios using artificial neural networks and the Canadian Earth System Model Second Generation (CanESM2). The Hargreaves method was used to calculate ET0 for western, central, and eastern parts of Prince Edward Island using their two input parameters: daily maximum temperature (Tmax), and daily minimum temperature (Tmin). The Tmax and Tmin were downscaled with the help of statistical downscaling model (SDSM) for three future periods 2020s (2011-2040), 2050s (2041-2070), and 2080s (2071-2100) under three representative concentration pathways (RCP’s) including RCP 2.6, RCP P4.5, and RCP 8.5. Temporally, there were major changes in Tmax, Tmin, and ET0 for the 2080s under RCP8.5. The temporal variations in ET0 for all RCPs matched the reports in the literature for other similar locations. For RCP8.5, it ranged from 1.63 (2020s) to 2.29 mm/day (2080s). As a next step, a one-dimensional convolutional neural network (1D-CNN), long-short term memory (LSTM), and multilayer perceptron (MLP) were used for estimating ET0. High coefficient of correlation (r > 0.95) values for both calibration and validation periods showed the potential of the artificial neural networks in ET0 estimation. The results of this study will help decision makers and water resource managers in future quantification of the availability of water for the island and to optimize the use of island water resources on a sustainable basis.

Micrometeorological modeling and water consumption of tabasco pepper cultivated under greenhouse conditions

Micrometeorological variables of tabasco pepper cultivated under greenhouse and drip irrigated conditions have not been presented to date in literature, especially the water consumption of these plants, in terms of crop evapotranspiration (ETc) and crop coefficient (Kc). The determination of these variables is extremely important for the application of the correct amount of water to irrigated crops in these environments because PM FAO (56) standard methodology was idealized for outdoor environments. The objective of this work was to develop models of estimation of micrometeorological variables in greenhouse conditions and to determine the water demand, in terms of evapotranspiration (ET) and Kc, of the pepper (Capsicum frutescens L.), cv. Tabasco McIlhenny, drip irrigated using drainage lysimeters. The research was carried out in an experimental area located at the University of Sao Paulo (USP) in Piracicaba, SP, Brazil. The following micrometeorological variables were monitored: air temperature, air relative humidity (digital thermohygrometer) and evaporation (mini-pan) (EMT). Drainage lysimeters were used to obtain the ETc and the reference evapotranspiration (ETo) was estimated outside the greenhouse by the Penman Monteith (EToPM), Hargreaves and Samani (EToHS) methods and the class “A” pan method (ECA). It was concluded that the total value of mini-pan evaporation (EMT) inside the greenhouse was practically equal to EToPM, 5% lower than EToHS and 31% higher than ECA in the outdoor environment. ET values ranged from 0.28 to 2.42 mm day-1 and total crop ET was 446.43 mm. The Kc values for the first pepper production cycle were: 0.17 in the initial phase, 0.76 in the flowering and fruiting phase and 0.39 in the harvest phase, for the second production cycle, the value of Kc was 0.50 at the harvest phase.

Application of the Hargreaves method for calculating the potential evapotranspiration in the hydrological modelling

To improve the results of the Slovenian Environment Agency’s hydrological forecasting system, especially in the river basins with lower specific runoff (Pomurje) and during high water events following a long dry period, we decided to find a good method for calculating daily values of the potential evapotranspiration (PET). We were deciding between several temperature-based methods for the daily reference evapotranspiration (ET0) values calculation. For selected meteorological stations we calculated ET0 using three different methods and then compared them to the ET0 values calculated using the much more complex Penman-Monteith method. Among the tested temperature methods the results given by the Hargreaves method fitted best to the results of the Penman-Monteith method. The reason for this may lie in the fact that the Hargreaves method, besides the mean daily air temperature as other temperature-based methods, considers the daily temperature range as well. Afterwards, considering the ground cover factor, we calculated the PET values from the ET0 values and then applied them in the hydrological modelling. The model setups for the Sava, Soča, and Mura Rivers were reanalysed twice, considering firstly the climatologic monthly PET values that were already used in the hydrological forecasting system of the Slovenian Environment Agency for many years, and, secondly the daily PET values calculated according to the Hargreaves method and using hourly air temperature 2 m above the ground, originating from the short-term weather forecasting model ALADIN or the INCA/AT meteorological system. At all selected calculation points, the model setups using daily PET values showed better performance over the model setups using climatological monthly values.

Estimación de la evapotranspiración a partir de datos satelitales para la región de Alto Beni, Norte de La Paz

La evapotranspiración (ET), resulta de un proceso simultáneo de evaporación y la transpiración. En una superficie de referencia, que ocurre sin restricciones de agua, se denomina como evapotranspiración del cultivo de referencia (ETo). Para este estudio se utilizó ecuación de Penman-Monteith FAO, propuesta por Allen, Pereira, Raes y Smith (2006); Thornthwaite et al. (1944); Hargreaves et al. (1985); Blaney y Criddle (1950) y Turc (1961). La información climática necesaria para la estimación de la ETo, no es suficiente debido a que las estaciones meteorológicas locales son muy escasas adema dejaron de funcionar, en ese sentido se utilizaron datos de los simuladores recomendados por la FAO LocClim (2005) y NASA (power larc). La región de Alto Beni se extiende; 14º 56' 55'' a 15º 56' 14'' Sur y longitud 66º 48' 04'' a 67º 36' 42'' una altitud de 300 a 1 800 m s.n.m. ocupan una extensión de 4 836.62 km2. Es una zona agrícola de importante, debido a que proporciona a la ciudad una buena parte de sus productos alimenticios. Los resultados de la ETo obtenidos en la modelación espacial, muestran diferentes valores distribuidos en la región, el cual varía en cada estación del año. Se asevera que, en la mayoría de los métodos, el déficit de agua inicia a medio mes de abril hasta septiembre, y los picos más altos de octubre a marzo. El análisis estadístico entre los resultados de la ETo, verifica que el modelo de Thornthwaite es el más aceptado con un coeficiente de correlación R2 de 0.966 seguida de Blaney-Criddle con 0.969, en último lugar los métodos de Hargreaves y Turc. El modelo más aceptado y aplicado para la zona es el Thornthwaite el cual tiene un comportamiento muy similar al PM-FAO el mismo no sobre estima las demandas de agua y sus cálculos son reflejados con los eventos de la región.

Water Requirement for Maize Crop Under Climate Change in Mirab Abaya Woreda, Southern Ethiopia

Climate change is a topic of discussion worldwide including in Ethiopia. Ethiopia is one of the country’s most vulnerable to the impacts of climate variability and change on agriculture. This study investigates were to examine crop water requirements under climate changes scenarios for maize crop at Mirab-abaya woreda which is situated in 6.18◦ N latitude and 37.77◦E longitude. Dynamically downscaled climate model outputs were obtained from the CORDEX-Africa program for (RCP) Representative Concentration Pathway of both scenarios which were used for future climatic conditions of the future periods; (2021 – 2050). The projected data was quality checked, biased corrected and model performance was evaluated. Mann Kendall's trend detection and Sen.’s slope estimator were used by XLSTAT software to evaluate the trends of projection and to detect changes. Hargreaves method was used to estimate current and future crop evapotranspiration of Maize. The result for observed and future revealed that the maximum and minimum temperatures increase in all time horizons. However, Projections of future rainfall suggest that annual rainfall decreases in both scenarios, the current and future potential evapotranspiration show that increasing trend in both cases except the observed Mirab-abaya station.

SUR1, newly expressed in astrocytes, mediates neuropathic pain in a mouse model of peripheral nerve injury.

BackgroundNeuropathic pain following peripheral nerve injury (PNI) is linked to neuroinflammation in the spinal cord marked by astrocyte activation and upregulation of interleukin 6 (IL-6), chemokine (C-C motif) ligand 2 (CCL2) and chemokine (C-X-C motif) ligand 1 (CXCL1), with inhibition of each individually being beneficial in pain models.MethodsWild type (WT) mice and mice with global or pGfap-cre- or pGFAP-cre/ERT2-driven Abcc8/SUR1 deletion or global Trpm4 deletion underwent unilateral sciatic nerve cuffing. WT mice received prophylactic (starting on post-operative day [pod]-0) or therapeutic (starting on pod-21) administration of the SUR1 antagonist, glibenclamide (10 µg IP) daily. We measured mechanical and thermal sensitivity using von Frey filaments and an automated Hargreaves method. Spinal cord tissues were evaluated for SUR1-TRPM4, IL-6, CCL2 and CXCL1.ResultsSciatic nerve cuffing in WT mice resulted in pain behaviors (mechanical allodynia, thermal hyperalgesia) and newly upregulated SUR1-TRPM4 in dorsal horn astrocytes. Global and pGfap-cre-driven Abcc8 deletion and global Trpm4 deletion prevented development of pain behaviors. In mice with Abcc8 deletion regulated by pGFAP-cre/ERT2, after pain behaviors were established, delayed silencing of Abcc8 by tamoxifen resulted in gradual improvement over the next 14 days. After PNI, leakage of the blood-spinal barrier allowed entry of glibenclamide into the affected dorsal horn. Daily repeated administration of glibenclamide, both prophylactically and after allodynia was established, prevented or reduced allodynia. The salutary effects of glibenclamide on pain behaviors correlated with reduced expression of IL-6, CCL2 and CXCL1 by dorsal horn astrocytes.ConclusionSUR1-TRPM4 may represent a novel non-addicting target for neuropathic pain.

Potreba za navodnjavanjem kukuruza na zemunskom černozemu u poslednjih pola veka

The aim of this paper is to examine the water regime of chernozem under maize crops in the last half century (1966-2019) and to determine whether during that period and to what extent, there was an increase or decrease in maize irrigation requirements. The mathematical plant model FAO CROPWAT 8.0 was used for the calculation. The calculation was performed on the basis of monthly values of reference evapotranspiration (ETo) for the period 1966-2019, calculated by the modified Hargreaves method, daily values of precipitation from the meteorological station Surcin, data on the selected plant, which are in accordance with FAO56. The soil is chernozem on the Zemun les terrace. The analysis was performed by dividing the research period into three subperiods: the first twenty (1966-1985), the second twenty (1986-2005) and the last fourteen (2006-2019) years. It was found that the average values of potential evapotranspiration of maize were increasing, starting from the first (500mm) to the third (562mm) subperiod, while the average values of actual evapotranspiration, as well as the average amount of effective precipitation in the vegetation period of maize, decreased. Consequently, the average water deficit, i.e. maize irrigation requirements was increased by 56%, starting from the first (205mm) to the third (319mm) subperiod of the research. The increase in the water deficit also caused an increase in the projected reduction in maize yield related to its genetic capasity, which averaged 31% in the first subperiod and 47% in the third. Analysis of the results on a monthly and decadal level showed that maize irrigation requirements lasts from June to August, with a maximum in the second decade of July. In all three summer months, an increase in maize irrigation requirements was registered from the first to the third subperiod of the research, with the maximum increase during July. The conducted research, which generally gives an insight into the state of the water regime of Zemun chernozem in the last half century, shows that the conditions of maize production in the natural rain regime are deteriorating and that the irrigation requirement is increasing.

Skin temperature contribution to the decrease in withdrawal latency following chronic constriction injury

BackgroundChronic constriction injury (CCI) is widely used as an animal neuropathic pain model. Neuropathic pain is considered to exist when withdrawal latency to thermal stimulation is decreased after inducing a CCI to the sciatic nerve. However, it is known that CCI leads to changes in skin temperature and that skin temperature can affect withdrawal latency. Aim of this study was to compare withdrawal latencies of constricted and contralateral hind limbs, to thermal stimulation, at the same artificially-induced skin temperatures. MethodsNeuropathic pain was induced by four ligatures on the left sciatic nerve in adult male Wistar rats. Withdrawal latencies were measured from the 11th to 14th day after ligation, in different ambient temperatures, using the plantar test (Hargreaves method). By changing ambient we produced different hind limb skin temperatures. ResultsOur results show that (1) CCI cause an increase in skin temperature; (2) the withdrawal latency was inversely related to ambient and skin temperature in the same manner for both the ligated and contralateral hind limbs; and (3) withdrawal latencies did not differ significantly for the ligated and contralateral hind limbs when the temperature of the hind limbs was artificially made the same (i.e., by changing the ambient temperature). ConclusionsWithdrawal latencies to thermal stimulation did not differ on ligated and contralateral hind limb after CCI to the sciatic nerve if the temperature of the hind limbs was artificially or mathematically made the same. This finding may have significant impact on the interpretation results of neuropathic pain research.

Future changes in meteorological drought characteristics over Bangladesh projected by the CMIP5 multi-model ensemble

Drought is an inconspicuous natural disaster. In a warmer world, the severity and coverage of drought are expected to change, and it is essential to study these changes at smaller scale. This study detected changes in drought frequency, severity, and intensity in Bangladesh from a bias-corrected CMIP-5 multi-model projection of 11 members under a business-as-usual RCP8.5 scenario. We have used two well-known meteorological drought indices, Standardized Precipitation Index (SPI) and Standardized Precipitation and Evaporation Index (SPEI). SPI is solely based on precipitation, while SPEI considers climatic water balance and incorporates the effect of temperature. Two different methods of estimation of potential evapotranspiration (PET), namely Thornthwaite and Hargreaves methods, are explored. SPEI-based drought identification is found to have high sensitivity among these PET estimation methods. In Bangladesh, SPI-based analysis suggests virtually no change in the long-term drought (12-monthly) condition and a minor change in short-term (6-monthly or less) droughts. SPEI evaluated with Hargreaves method projects a similar scenario for long-term droughts but an increase in both drought frequency and severity in short timescales. At seasonal scale, winter and pre-monsoon are projected to be potentially more affected by water stress in the future. A spatially coherent shift in wet-dry regime is also found over the northern part of Bangladesh under the warming world.

Climate Change Induced Precipitation and Temperature Effects on Water Resources: the Case of Borkena Watershed in the Highlands of Wollo, Central Ethiopia

This study acquiring series issue of climate change which significantly affect the amount of precipitation and temperature at regional level, which intern would affect the water resources and future water availability of Borkena watershed located in the highlands of Wollo in Awash Basin, Ethiopia. Bias corrected Representative Concentration Pathways (RCP4.5 and RCP8.5) scenario data were used for precipitation and temperature projections in the 2050s. The projection result indicates mean annual precipitation increases at a rate of 14.70% and 13.21%; similarly, temperature increases by 1.16 °C and 1.59 °C, under both scenarios, respectively. After the projections of precipitation and temperature, Hydrological Modeling System (HEC-HMS) was used to simulate future streamflow and current evaporation estimated by Penman-Monteith while Hargreaves methods were used to estimate future evapotranspiration. The evaluation result showed that hydrological model is well performed for the watershed with daily R2 values 0.79 and 0.85 and Nash-Sutcliffe Efficiency (NSE) values 0.78 and 0.83 for calibration and validation periods, respectively. Results of this study present climate change induced temperature and precipitation changes significantly affect the monthly, seasonally, and annually evapotranspiration and streamflow of the watershed. The results show an increase in projected Potential Evapotranspiration (PET) at a rate of 2.77% and 3.20%; similarly, mean annual streamflow increases up to 22.63% and 14.57% under RCP4.5 and RCP8.5 scenarios, respectively. Seasonally, the mean streamflow during Kiremt and Bega expected to increase by 4.5% and 90.57% and 7.5% and 57.39%, but Belg season would decrease by 27.18% and 21.16% under RCP4.5 and RCP8.5 climate scenarios, respectively. These results are important to consider the influence of climate change on water resources of central Ethiopia, which is valuable for the planning and management of water resources in different watersheds of Ethiopia.

Estimation of Crop Water Deficit in Lower Bari Doab, Pakistan Using Reflection-Based Crop Coefficient

There is a global realization in all governmental setups of the need to provoke the efficient appraisal of crop water budgeting in order to manage water resources efficiently. This study aims to use the satellite remote sensing techniques to determine the water deficit in the crop rich Lower Bari Doab Canal (LBDC) command area. Crop classification was performed using multi-temporal NDVI profiles of Landsat-8 imagery by distinguishing the crop cycles based on reflectance curves. The reflectance-based crop coefficients (Kc) were derived by linear regression between normalized difference vegetation index (NDVI) cycles of the Moderate Resolution Imaging Spectroradiometer (MODIS) MOD13Q1 and MYD13Q1 products and Food and Agriculture Organization (FAO) defined crop coefficients. A MODIS 250 m NDVI product of the last 10 years (2004-2013) was used to identify the best performing crop cycle using Fourier filter method. The meteorological parameters including rainfall and temperature substantiated the reference evapotranspiration (ET0) calculated using the Hargreaves method. The difference of potential ET and actual ET, derived from the reflectance-based Kc calculated using reference NDVI and current NDVI, generates the water deficit. Results depict the strong correlation between ET, temperature and rainfall, as the regions having maximum temperature resulted in high ET and low rainfall and vice versa. The derived Kc values were observed to be accurate when compared with the crop calendar. Results revealed maximum water deficit at middle stage of the crops, which were observed to be particularly higher at the tail of the canal command. Moreover, results also depicted that kharif (summer) crops suffer higher deficit in comparison to rabi (winter) crops due to higher ET demand caused by higher temperature. Results of the research can be utilized for rational allocation of canal supplies and guiding farmers towards usage of alternate sources to avoid crop water stress.

Analysis of alternative climate datasets and evapotranspiration methods for the Upper Mississippi River Basin using SWAT within HAWQS

This study reports the application of Soil and Water Assessment Tool (SWAT) within the Hydrologic and Water Quality System (HAWQS) on-line platform, for the Upper Mississippi River Basin (UMRB). The UMRB is an important ecosystem located in the north central U.S. that is experiencing a range of ecological stresses. Specifically, testing of SWAT was performed for: (1) Hargreaves (HG) and Penman-Monteith (PM) PET methods, and (2) Livneh, National Climatic Data Center (NCDC) and Parameter-elevation Regressions on Independent Slopes Model (PRISM) climate datasets. The Livneh-PM combination resulted in the highest average annual water yield of 380.6 mm versus the lowest estimated water yield of 193.9 mm for the Livneh-HG combination, in response to 23-year uncalibrated simulations. Higher annual ET and PET values were predicted with HG method versus the PM method for all three weather datasets in response to the uncalibrated simulations, due primarily to higher HG-based estimates during the growing season. Based on these results, it was found that the HG method is the preferred PET option for the UMRB. Initial calibration of SWAT was performed using the Livneh data and HG method for three Mississippi River main stem gauge sites, which was followed by spatial validation at 10 other gauge sites located within the UMRB stream network. Overall satisfactory results were found for the calibration and validation gauge sites, with the majority of R2 values ranging between 0.61 and 0.82, Nash-Sutcliffe modeling efficiency (NSE) values ranging between 0.50 and 0.79, and Kling-Gupta efficiency (KGE) values ranging between 0.61 and 0.84. The results of an additional experimental suite of six scenarios, which represented different combinations of climate data sets and calibrated parameters, revealed that suggested statistical criteria were again satisfied by the different scenario combinations. Overall, the PRISM data exhibited the strongest reliability for the UMRB.

Use of Flavored Tablets of Gabapentin and Carprofen to Attenuate Postoperative Hypersensitivity in an Incisional Pain Model in Rats (Rattus norvegicus).

Providing postoperative analgesia to rats by oral administration, compared with injections, reduces stress from frequent handling and is technically easier for investigators. The purpose of this study was to investigate whether bacon-flavored tablets containing gabapentin, carprofen or a combination of both drugs effectively attenuates postoperative mechanical and thermal hypersensitivity in a rat model of incisional pain. Forty-eight Sprague-Dawley rats were randomly assigned to 1 of 5 treatment groups: placebo tablet; a single, subcutaneous injection of buprenorphine sustained release at 1.2 mg/kg; gabapentin 90 mg/tablet; carprofen 5 mg/tablet; gabapentin 90 mg and carprofen 5 mg/tablet (gabapentin/carprofen). Tablets were given to rats on days -3, -2, -1, 0 (surgery), 1, and 2. Rats were anesthetized using isoflurane. A 1 cm skin incision was made aseptically on the plantar surface of the left hindpaw and closed by using suture. Mechanical (von Frey monofilament) and thermal (Hargreaves method) hypersensitivity were tested daily, and analyzed on days -1, 1, 2, and 3. The amount of tablet consumed was recorded daily; postoperatively rats consumed 101 to 133 mg/kg of gabapentin, 5.5 to 5.8 mg/kg of carprofen, and 86-137/1.9-3 mg/kg of gabapentin/carprofen, respectively. Both the gabapentin and carprofen groups displayed attenuated mechanical hypersensitivity on all 3 postsurgical days and decreased thermal hypersensitivity on Day 3. The gabapentin/ carprofen group showed attenuated mechanical hypersensitivity on Day 2 and 3, but no significant reduction of thermal hypersensitivity. These data suggest that both gabapentin and carprofen, given orally by flavored tablet, effectively attenuate postoperative mechanical hypersensitivity for 3 d after surgery in a rat model of incisional pain.

Estimating Reference Evapotranspiration by Hargreaves and Blaney-Criddle Methods in Humid Subtropical Conditions

Various methods are available to predict reference evapotranspiration (ETo) but the Penman-Monteith (PM) ETo method has been considered to be the most accurate ETo method to determine ETo. The PM ETo method can be solved by various weather parameters like atmospheric temperature, wind velocity, moisture content and net solar radiations. There are many weather stations in the world that have no complete set of weather parameters to predict ETo by applying PM ETo method. So alternative ETo methods like Hargreaves (HG) and Blaney-Criddle (BC) ETo methods are used which need only a fewer number of weather parameters. In this paper, two ETo methods, HG and BC are compared with PM ETo method in humid subtropical climatic conditions of Islamabad and Kakul (Abbottabad) weather stations. The study indicate that HG ETo method overestimated PM ETo method by 23.78% at Islamabad weather station and 28.47% at Kakul station. The BC ETo method overestimated PM ETo method by 37.93% at Islamabad weather station and by 22.68% at Kakul weather station. The dissimilarity of HG ETo method with PM ETo method with RMSE was 1.09 mm/day at Islamabad weather station and 1.17 mm/day at Kakul weather station. The dissimilarity of BC ETo method with PM ETo method has Root Mean Square Error (RMSE) of 2.86 mm/day at Islamabad weather station and 1.48 mm/day at Kakul weather station.

RETRACTED: Molecular mechanism of electroacupuncture treatment on oxaliplatin-induced peripheral neurotoxicity in rats

Oxaliplatin (L-OHP) has been widely used in the treatment of various tumors, especially in colorectal cancer. The mechanism of peripheral neurotoxicity induced by L-OHP (OIPN) is unclear and current therapeutic options only serve to alleviate the symptoms rather than prevent OIPN. To observe the effects of electroacupuncture (EA) stimulation on OIPN in rats, rats were randomly divided into the control group, OIPN model group, and OIPN + EA group. To establish OIPN rat models, a single intraperitoneal injection with 10 mg/kg L-OHP in the OIPN model rats. Rats in the control group received a single intraperitoneal injection with 0.9% lactose. From the third day after establishing OIPN models, the rats were treated with EA. Cold allodynia and heat sensitivity were assessed using the acetone drop and the Hargreaves method, respectively. Pathological changes in nerves were detected using hematoxylin and eosin (H&E) staining and transmission electron microscopy. Related mRNA and protein expression levels were measured by real-time polymerase chain reaction (PCR) and western blotting from 14 days after establishing OIPN models. Our results showed that L-OHP significantly increased the sensitivity to cold allodynia and nervous injury, which were ameliorated after EA treatment. The expression of glucocorticoid receptor alpha (GR-α) and B-cell lymphoma 2 (Bcl-2) was significantly decreased and that of Bax was significantly increased in sciatic nerve of OIPN model rats compared with control rats. However, EA treatment significantly inhibited L-OHP-induced protein expressions in rats. Moreover, compared with the control rats, the nucleus NF-κBp65 levels were significantly increased, while the cytoplasm NF-κBp65 levels were significantly decreased, which were reversed by EA treatment. In conclusion, EA treatment may reduce peripheral neurotoxicity induced by L-OHP through regulating related protein expression.

Statistical and spatial variability of climate data in the Mareb-Gash river basin in Eritrea

Introduction. Global reanalysis products are extensively used for hydrologic applications in sparse data regions. The establishment of inputs for hydrologic modelling from such global reanalysis requires prior checking and analyses.
 Materials and methods. The present study attempts to utilize Climate Forecast System Reanalysis (CFSR) datasets for the Mereb-Gash river basin in Eritrea, to prepare the input data for forthcoming hydrological modelling studies. The activities include statistical analyses, computation of PET, and drought indices using different methods so as to understand basin characteristics through the use of geospatial and geostatistical tools.
 Results. The results of statistical analyses indicated that there was predominantly a significant monotonic trend in the majority of the data. Precipitation (P) and relative humidity tend to decrease, whereas temperature (T) and potential evapotranspiration (PET) tend to increase. Among the PET estimation methods, the Thornthwaite method gave inconsistent results as compared to Hargreaves and Penman-Monteith methods, the former being highly dependent on the elevation of the station. In most cases, it was found that Penman-Monteith produced the highest PET values.
 Conclusions. Besides, Standardized Precipitation and Evapotranspiration Index (SPEI) analyses in the basin indicate persistent dry conditions over the period 2000–2013 and predominantly humid conditions over the period 1979–2000. The study concluded that the presence of a significant trend in most of the climatic variables and persistent drought conditions in recent years were found to be congruent with global and regional climatic studies that are highly likely linked to human and climate influence on the environment.

Estimation of evapotranspiration rate by using the Penman–Monteith and Hargreaves formulas for the loess in Northeast Bulgaria complex with HYDRUS-1D

Loess and loess-like sediments cover approximately 13% of the Bulgarian territory, mainly within the Danubian plain. From the Danube River to the Fore-Balkan, the loess soils form a loess complex where its depth varies from 50–60 meters in the north to few meters in the south, respectively. Widespread loess sediments possess a specific feature: they typically form deep unsaturated zones. Quantification of the near surface water balance is extremely important for evaluating land-atmosphere interactions, and the impact of land-use change on the subsurface flow and the evapotranspiration rate is an essential term in this quantification. In the frames of a scientific project, an automatic weather station was installed in a typical plain terrain of the loess complex in Northeast Bulgaria, recording meteorological data from September 2015 to February 2017. This study provides a mathematical description of processes (i.e., Penman-Monteith and Hargreaves Methods) used to estimate daily evapotranspiration rates implemented into the numerical model HYDRUS-1D, as well as a respective rate investigation of months with and without intensive rainfalls. Overall results indicate that using the Hargreaves formula for evaluation of the potential evapotranspiration leads to overestimation between 10% and 20%, respectively for a “wet” and “dry” month.

Spatiotemporal trends in reference evapotranspiration over South Korea

The universal phenomena of global warming caused by climate change have direct linkage with different hydro-meteorological variables which in turn affect the evaporative demand of the atmosphere. Therefore, this study evaluated the seasonal and spatial changes in reference crop evapotranspiration (ETo) during last 4.7 decades and identified the forcing mechanism behind the seasonal changes in ETo using a stepwise regression equation. To remove the effect of serial correlation, the modified Mann–Kendall test was adopted together with Sen's slope and linear regression method to identify and compare the spatial and temporal trends between Thornthwaite, Hargreaves and FAO Penman–Monteith (FAO-PM) methods. Results indicate that the annual average ETo value is higher along the south and east coastal areas and lower along the northwest side of South Korea. The highest number of stations with significant increasing trends was detected in Thornthwaite and significant decreasing trend in FAO-PM method. Spatial and temporal correlation analysis showed the existence of strong correlation between Hargreaves and FAO-PM methods with the Pearson r value ranging from 0.84 to 0.98 and R2 of 0.8. Wind speed is found to be the most influencing climatic variable, especially in autumn, early winter and early summer, and maximum temperature during spring and late summer.

Rapid-stretch injury to peripheral nerves: implications from an animal model.

Rapid-stretch nerve injuries are among the most devastating lesions to peripheral nerves, yielding unsatisfactory functional outcomes. No animal model has yet been developed that uses only stretch injury for investigation of the pathophysiology of clinical traction injuries. The authors' objective was to define the behavioral and histopathological recovery after graded rapid-stretch nerve injury. Four groups of male B6.Cg-Tg(Thy1-YFP)HJrs/J mice were tested: sham injury (n = 11); stretch within elastic limits (elastic group, n = 14); stretch beyond elastic limits but before nerve rupture (inelastic group, n = 14); and stretch-ruptured nerves placed in continuity (rupture group, n = 16). Mice were injured at 8 weeks of age, comparable with human late adolescence. Behavioral outcomes were assessed using the sciatic functional index (SFI), tapered-beam dexterity, Von Frey monofilament testing, and the Hargreaves method. Nerve regeneration outcomes were assessed by wet muscle weight and detailed nerve histology after 48 days. Post hoc biomechanical assessment of strain and deformation confirmed that the differences between the elastic and inelastic cohorts were statistically significant. After elastic injury, there was a temporary increase in foot faults on the tapered beam (p < 0.01) and mild reduction in monofilament sensitivity, but no meaningful change in SFI, muscle weight, or nerve histology. For inelastic injuries, there was a profound and maintained decrease in SFI (p < 0.001), but recovery of impairment was observed in tapered-beam and monofilament testing by days 15 and 9, respectively. Histologically, axon counts were reduced (p = 0.04), muscle atrophy was present (p < 0.01), and there was moderate neuroma formation on trichrome and immunofluorescent imaging. Stretch-ruptured nerves healed in continuity but without evidence of regeneration. Substantial and continuous impairment was observed in SFI (p < 0.001), tapered beam (p < 0.01), and monofilament (p < 0.01 until day 48). Axon counts (p < 0.001) and muscle weight (p < 0.0001) were significantly reduced, with little evidence of axonal or myelin regeneration concurrent with neuroma formation on immunofluorescent imaging. The 3 biomechanical grades of rapid-stretch nerve injuries displayed consistent and distinct behavioral and histopathological outcomes. Stretch within elastic limits resembled neurapraxic injuries, whereas injuries beyond elastic limits demonstrated axonotmesis coupled with impoverished regeneration and recovery. Rupture injuries uniquely failed to regenerate, despite physical continuity of the nerve. This is the first experimental evidence to correlate stretch severity with functional and histological outcomes. Future studies should focus on the pathophysiological mechanisms that reduce regenerative capacity after stretch injury.

Estimating impact of weather factors on wheat yields by using panel model approach — The case of Serbia

In Serbia irrigation is not widely utilized to reduce water scarcity in crop production. Therefore, wheat yields largely depend on weather factors. Over the past two decades, there has been recorded a significant change in weather conditions in Serbia. Such change produces concerns about Serbia’s food security and exports since wheat is among the most important agricultural products. In this paper authors analyze and quantify the impact of weather factors on the achieved wheat yields, using a set of panel data on selected Serbian municipalities in fourteen years (2000–2013). The multidimensional regression was conducted as a sort of quasi-experiment, combining data on achieved yields in selected municipalities, with data on weather factors: temperature, precipitation, extraterrestrial radiation, and evapotranspiration. Utilizing the Hargreaves method of determining reference evapotranspiration, average daily water deficit was computed as a single representative indicator of weather conditions. Testing was conducted on four predefined sub-periods within the vegetation season of wheat, and the impact of average daily water deficit on wheat yields was estimated for each of these sub-periods. Results show a robust, statistically significant impact of change in average daily water deficit on decreased wheat yields. Growth of water deficit by 0.1 mm, in the period November 15th to April 1st results with 175 kg/ha lower yields, while in the period April 1st to May 15th results in 45 kg/ha lower yields. Impact shows to be conditional on the altitude, rapidly losing on intensity and significance above 100 m.