The aim of this research was to quantify the seasonal variations in rainfall interception (I) by individual ash trees (Fraxinus rotundifolia Mill.) during growing season (GS), and non-growing season (NGS) in Chitgar forest park located in the semiarid climate zone of Iran, near Tehran. From September 2012 to September 2013, gross rainfall (GR) and TF were collected through 6 and 12 rain-gauges, respectively, in an open area and under the tree crown. Rainfall interception was calculated as the difference between GR and TF. Fifty rainfall events were recorded and the cumulative GR was measured 156.0 mm. Over the study period, GS, NGS and I ranged 19.4%, 23.0%, and 16.2%, respectively. Significant positive correlations were observed between I and GR over the study period (r2= 0.780), GS (r2= 0.743), and NGS (r2= 0.903) (p<0.01). During the measurement period, GS, and NGS, the percentage of the relative interceptions (I: GR) % were estimated to be 46.6%, 49.3%, and 41.6%, respectively. T-test suggested that there were significant differences between the (I: GR) % values within GS and NGS (p<0.01). It is important to select species trees with lower I values for plantation, since they increase the higher amounts of net rainfall (NR) in semiarid and arid regions where water availability is a limiting factor for plantations growth. Transpiration as well as litter interception of selected trees should be also considered.

Recognation of performance and prediction of how climate change and human activities affect the groundwater resources is necessary in Groundwater resources management. Groundwater resources play an important role in supplying domestic, agricultural and industrial water in semi arid regions. In such regions, increasing population and water demand along with the climate change, causes negative effect on groundwater guality and quantity. In this research important factors influncing groundwater quality and quantity changes has been investigated. In the first step, GMS10. 05 software was used for determining and simulating characteristics of Mahabad aquifer, in western Iran. After calibration and validation of model, we researched about effective factors influncing groundwater change. To this aim, results was obtained without human activity factors in the first run. In this condition average of groundwater level was obtained to be 3 meters higher than the groundwater level observations. Investigating the constraction of dam as an anthropogenic activity factor showed that the dam construction causes groundwater level to be 1. 11 meters lower than the pervious condition. We then predicted the groundwater EC and SAR using GEP as a function of groundwater level. We concluded that anthropogenic activities in comparison to the natural changes are the primary force which demolishes the groundwater level and guality and changing the irrigation of groundwater class to C3S1. The result of this study is applicable in developing criteria for adaptation groundwater resouce management in future.

The main goal of this study was to compare of rainfall interception (I) by Pinus eldarica and Cupressus arizonica plantations afforested in the Chitgar Forest Park in a semiarid climate zone of Iran. From the September 2012 to September 2013, gross rainfall (GR) and throughfall (TF) were collected through 10 and 50 rain-gauges, respectively. I was calculated as the difference between GR and TF. During the measurement period, fifty five rainfall events with the cumulative value of 262.5 mm were recorded. Over the study period, I was calculated 80.0 mm (30.5%), and 60.3 mm (23.0%) for P. eldarica and C. arizonica, respectively. The percents of the interception (I:GR)% were estimated 46.8% and 37.8%, respectively. Significant positive correlations were observed between I and GR by P. eldarica (I= 0.135GR+0.811; r= 0.663), and C. arizonica (I= 0.100GR+0.620; r= 0.757) afforestations (P < 0.05). T-test suggested that there were significant differences between the (I:GR)% values at the small and very small storms classes (0.1-5.0 mm) between P. eldarica and C. arizonica (P < 0.01). The greater interception loss by P. eldarica proposed that in this climate zone, it is preferable to plant C. arizonic relative to P. eldarica trees.

Forest canopy rainfall interception loss (I), canopy water storage (S), and the ratio of mean evaporation to mean rainfall intensity ( E-/R-) are important components of the water balance in arid and semi-arid climate zones. The goal of this project was to quantify I and S and to evaluate the Gash interception model for rainfall interception in a mature semi-arid Pinus eldarica Medw afforestation planted in the Chitgar Forest Park near Tehran city, Iran. Measurements of gross precipitation (PG) and throughfall (TF) were recorded on an event basis from September 2009 to April 2010. For the measurement period, PG totaled 164.8 mm and I totaled 61.2 mm. I was calculated as the difference between PG and TF. On the event scale, the ratio of I:PG ranged between 0.195 and 1, and averaged 0.614. There was a strong logarithmic correlation between I: PG and PG (R2=0.861; P value£0.01). As the size of rainfall events increased, I:PG decreased. The mean method estimated S to be 1.8 mm. The Gash model accurately estimated I to be within 1.1 mm of the total measured value. The results demonstrate that intercepted rainfall represents a considerable portion of PG in P.eldarica afforested regions of the semi-arid climate zone of Iran where soil moisture is a limiting factor for plant growth and productivity.

Rice is one of the most important plants, which grows in different provinces located in north, south and western parts of Iran through a high level of flooding surface irrigation systems with low efficiency. On the other hand, suitable irrigation management programming and the awareness of crop coefficients and exactly, the water requirement of different varieties of this crop is essential in different plant stages. This study was conducted to determine the crop coefficients of rice (Amberbo cultivar) during years 2017 and 2018. For this purpose, water balance drainable lysimeters with a diameter and height of 1. 20m and 1. 40m were used in farm and glasshouse condition, separately. In this regard, the Penman-Monteith equation for potential evapotranspiration and water balance equation to measure actual evapotranspiration were used to calculate potential evapotranspiration. Finally, the average values of crop water requirement and Ambarbo rice crop coefficients were determined in non-flooding condition for different initial, development, middle, and end stages in the farm and glasshouse condition as (584. 59 mm, 0. 96, 1. 07, 1. 25, and 0. 95) and (616. 28 mm, 1. 00, 1. 10, 1. 29, and 1. 05), respectively. The results of this research showed that a lot of rice irrigation water could be saved under Non-Flooding Irrigation Conditions. Therefore, with the saved water, more lands will be cultivated and more production, income and jobs will be provided for the villagers.

Iran was located in the arid belt and desert region of the world. This climatic situation was presented in several parts of Iran such as Qazvin. Evapotranspiration is one the most important parameter which was effect on agricultural development. There are different methods for estimating this item which selected by climatic conditions. This research concentrates to evaluate 28 empirical and combined methods in Qazvin plain. Lysimeter data was selected as a base data and daily results of 28 methods was evaluated with lysimeter. The results showed that Hargreaves-Samani as empirical method and temperature group with r=0. 87, RMSE=0. 34 mm/day and MBE=-0. 71 mm/day is best method in Qazvin. Orang from pan evaporative method was more appropriated daily results with lysimeter data. To estimate evaporate from free water surface, Penman 1948 is the best method which has highest correlation coefficient (0. 7) and lowest standard error (1. 65 mm/day) and also mean absolute error (8. 63E-6 mm/day). Amount of average evaporating from water surface with Penman method was calculated 10. 18 mm/day.

This study was carried out to investigate the effect of age at first calving (AFC) on calving interval (CI) and dry period length (DP) of dairy cows in semiarid climate of Iran. Records of 57870 first lactation dairy cows were collected from 601 herds during 1995 to 2009 by the Animal Breeding Center of Iran. The analysis was performed using mixed models procedure. Variance components were estimated via restricted maximum likelihood method in a univariate animal model using DMU software. The data were divided in two groups as AFC£26 mo (group 1) and AFC>26 mo (group 2). The average AFC for all data, group 1 and group 2 were 26 (±2.5), 24 (±1) and 28 (±2.5) mo, respectively. The average CI and DP were 375 (±47), 67 (±20) day for group 1 and 380 (±50), 69.5 (±22) day for group 2, respectively. The estimates of heritability of CI and DP were 0.037 (±0.008), 0.022 (±0.006) for group 1 and 0.026 (±0.009), 0.00 for group 2, respectively. Phenotypic trend of CI and DP was negative and significant for two groups (P<0.05). The difference between average estimated breeding values of CI and DP for group 1 were lower than group 2 and significant (P<0.01). The results of this study showed that cows calving at a young age in semiarid climate of Iran had lower CI and DP during their first lactation.