In this study a simple simulation model for the design of microcatchment water harvesting systems for rain-fed tree cultures in the Bajgah area, Fars province, I. R. of Iran, was developed. The actual daily evapotranspiration was calculated during the years 1984 to 1987. This model has been calibrated based on 34 measured volumetric soil water contents at depths of 120 cm, and soil water at depths of 0-120 cm in the study area. To calculate the daily actual evapotranspiration during these years, daily crop coefficient, the coefficient of evaporation from the soil surface, mean daily soil water stress coefficient for four years (1984-1987) and the Penman-FAO method for the calculation of reference crop potential evapotranspiration (ETo)   were used. The results indicated that the total amounts of actual evapotranspiration (ETa) for growing seasons were 407, 346, 376 and 362 mm (mean value of 373 mm). Also, the values of yearly ETa were 537, 472, 488 and 485 mm (mean value of 496 mm). Furthermore, a simple method based on Type III Pearson distribution and Penman-FAO ETo was used to estimate the amount of actual evapotranspiration for different probabilities of occurrence in each month of the year. So, the total amount of actual evapotranspiration during the growing season can be obtained for different probabilities of occurrence. Moreover, by using the yearly actual evapotranspiration and yearly rainfall with different combinations of probabilities, the microcatchment areas were estimated for different probabilities of occurrence. These data were used in a simple equation for determining the microcatchment area based on the probability of annual rainfall and yearly ETa. The results indicated that with 50 % probability of annual rainfall and yearly ETa, the microcatchment area (sum of cropping and runoff areas) was estimated to be about 8.7 m2 (cropping area=1.8 m2 and runoff area=6.9 m2). According to the indigenous knowledge of the local farmers, the microcatchment size in the study area is also 9 m2, which is similar to the microcatchments size with a 50 % probability.

Present research has been executed in Chaharmahal va Bakhtiary Province during 5 years in order to investigation of impact of optimized microcatchment systems in moisture storage of soil profile for establishment and development of hillside orchards. Essential hypothesis in this research is the practicability of moisture storage in soil profile by using microcatchment systems. Towards this attempt, in a rangeland of 20 percent slope, microcatchments were made with 5 different treatments including natural surface, removed surface with gravelly filter, removed surface without gravelly filter, isolated surface with gravelly filter and isolated surface without gravelly filter, with 5 replicates and 3 cultivar of almond. Soil moisture was measured in the times of, one day after rainfall, one day befor irrigation, one day after irrigation and once in each 5 days by TDR in depth of 25, 50 and 75 centimeters of soil profile of cultivated ditch. Comparison of means of soil moisture showed that in depth of 25 centimeters of soil profile, different treatments had not effective role in soil moisture variations. In depth of 50 centimeters, the means of moisture value had significant difference between different treatments. In depth of 75 centimeters, the means of moisture value had significant difference between removed surface with gravelly filter and removed surface without gravelly filter(p<0. 05) and also between isolated surface with gravelly filter and isolated surface without gravelly filter(p<0. 04). So utilization of optimized microcatchment systems especially isolated surfaces with gravelly filter can be recommended for increasing of moisture storage of soil profile in hillside orchards.

This paper describes a subroutine for estimation of daily and average annual runoff in a computer model for microcatchment design and prediction of rain-fed grape yield in the Bajgah area, Fars province, Islamic Republic of Iran. In this subroutine, it is assumed that all abstractions arise from infiltration, and a method for determining ponding time and infiltration by using recording rain gage data and soil physical properties was developed based on the Green-Ampt infiltration equation. This subroutine was then incorporated into a previously developed model to design the microcatchment area and grape yield prediction. The developed subroutine resulted in a daily microcatchment runoff coefficient of 0.0737 in the study area which is similar to the measured value of 0.080. The daily threshold rainfall to produce daily runoff estimated by the developed subroutine was 6.5 mm where its measured value was 4.6 mm. The developed subroutine resulted in a microcatchment average annual runoff coefficient of 0.0894 in the study area, which is similar to the measured value of 0.0875. The annual threshold rainfall to produce annual runoff was estimated by the developed subroutine, and was 158.8 mm where its measured value was 106.5 mm. The estimated relationship between annual runoff and rainfall was used in the model and estimated the microcatchment area and grape yield properly. In general, it is indicated that the developed subroutine is able to determine the daily and annual runoff-rainfall relationship to be used in the model for the design of the micricatchment area and prediction of grape yield in the study area.

During the last few decades, the ecosystem of natural areas has suffered as a result of improper exploitation of water and soil resources. To revive and develop renewable natural resources, it seems important to analyze and optimize rainfall storage systems and provide integrated techniques. Rainwater harvesting, in conjunction with plant species cultivation, is critical in the restoration and improvement of rangeland, particularly in dry areas. The present research was conducted with the aim of investigating the effect of rainwater harvesting methods (contour furrow and microcatchment) on increasing the percentage of vegetation cover in the Khajeh research station in East Azerbaijan province. To accomplish this, two methods of rainwater harvesting system, contour furrow and microcatchment, were established in the form of a randomized complete block design with three repetitions, in a land with a slope of 2-6%. After preparing the plots, Agropyron elongtum was planted in the form of seeding. Vegetation cover percentage was measured from the second year of planting for three years. A linear transect was used to determine vegetation cover percentage. The results showed that the microcatchment treatment significantly increased vegetation cover compared to the control. So that with the construction of the microcatchment, the vegetation cover increased about 183% (three times) compared to the control. In the case of contour furrow treatment, an increase of about 53% was observed compared to the control treatment. The microcatchment method performed better than the contour furrow, so that it increased the vegetation cover by about 85%. Therefore it seems the microcatchment is the best rainwater harvesting system in terms of increasing vegetation cover in the study area.

Background and objectives: A large area of Iran rangelands is located in arid and semi-arid areas which a significant percentage of them have been degraded and are not in good condition. In these areas, vegetation restoration is not easy due to the water scarcity. Water harvesting operations are among the necessary management measures to restore and develop the rangelands of these areas. Water harvesting operations improve the rangeland restoration conditions by increasing the available moisture for plants. But not all water harvesting operations are equally effective and may not have the same effect on rangeland restoration in different areas. Therefore, it is necessary to compare such operations in different areas to be able to choose the best water harvesting operations. Therefore, this study investigates the efficiency of two water harvesting methods in the rehabilitation of arid vegetation in Hormozgan province. Methodology: In this study, three treatments have been considered: control area, area under microcatchment operation and area under water spreading system. Systematic-random sampling method was used to measure vegetation. Three 100 m transects were laid out in each area. Vegetation attributes were measured in ten 2×2 m plots located along each transect. In total 90 plots, the percentage of canopy cover and the number of the plant species were recorded. The biological form of plant species was determined based on the Rankier classification method. In addition, the percentage of rocks and pebbles, litter and bare soil were determined in each plot. To study the flora of the study area, all plant species in the region were sampled and identified using reliable references. To evaluate species composition in all three sites, plant functional types were used. One-way analysis of variance followed by LSD were used to compare control area, area under microcatchment operation and area under water spreading system in terms of vegetation attributes. The rate of vegetation attributes change was also determined. Detrended correspondence analysis was used to investigate the relationship between plant species and water harvesting operations and control areas. Results: The results showed that there was a significant differences between water harvesting operations and control areas in terms of bare soil, litter and vegetation (P <0. 05) The water spreading system and microcatchment operation had a significant effect on vegetation canopy and litter cover in the region (P <0. 05). Examination of plant functional types also showed that palatability classes II and hemicryptophytes had more chance to develop under water harvesting operations respectively. In terms of life form, water harvesting operations had the most positive effect on forbs and grasses, respectively (P <0. 05). The results also showed that the families Poaceae, Chenopodiaceae and Fabaceae were successful families in the sites under water harvesting operations, especially the sites under water spreading system. The rate of vegetation attributes change was increasing in the area under water spreading system compared to the area under microcatchment operation, except for the bare soil. The highest and lowest positive changes belonged to litter and Simpson index with a mean of 9. 07±0. 62 and 0. 48±0. 25, respectively. The results of DCA showed that Cenchrus pennisetiformis، ، ‏Tephrosia persica، ‏Atriplex leucoclada‏، ‏Cornulaca monacantha‏, ‎ ‎Cynodon dactylon were the most important species related to water spreading system and microcatchment operation. Conclusion: Both water spreading system and microcatchment operations improved the quality and quantity of vegetation in the region, but the effects of water spreading system were greater than microcatchment operation in restoring vegetation. According to the ecological indicators considered in this study, water spreading system is recommended to restore vegetation in arid and semi-arid regions. In the end, it is suggested that economic and social indicators such as the cost of implementing various water harvesting operations should be also considered in future studies, to combine all ecological, economic and social indicators to suggest the best water harvesting operations for rangeland restoration.

The aim of this study is economic analysis of supplemental irrigation (SI) for rain-fed fig trees in the south of Iran, with and without micro-catchment water harvesting systems (MCWHS). Under no MCWHS, by decreasing about 55 % of applied water, the fig yield decreased about 28% and net income increased twice compared with the maximum yield condition. In general, the optimal amount of SI water would be lowered by using MCWHS in comparison with no using MCWHS. By using MCWHS, decreasing about 50 % of applied water causes about 14 % decrease in fig yield and net income increased twice compared with maximum yield condition. In order to obtain high net profit with a given amount of annual rainfall, the amount of optimal SI water decreased by increasing the unit price of water. An equation is proposed for the prediction of annual precipitation which may be used for planning SI for the fig trees in the study region.

A sensitivity analysis was done for soil water balance model for rain-fed vineyard in microcatchrnents in Bajgah area, Fars province. The objective of this study was determination of the effective and less effective of parameters. To do it, important parameters such as daily maximum and minimum temperature together, daily maximum and minimum relative humidity together, daily wind speed at 2 m above ground surface, daily sunshine, field capacity of each soil layers and wilting point together, readily water available coefficient and crop coefficient were considered and +I0 % and -10 % were added to them, separately.Then, the results of model estimation of volumetric soil water contents in depth of 120cm, and the amount of soil water at depths of 0-120cm were compared with the measured data. The results indicated that field capacity and crop coefficient were more sensitive and the other parameters that used for calculating reference crop potential evapotranspiration, had less sensitivity.

Present research has been executed in Kerman Province during 5 years in order to hillside orchards development by using rainwater harvesting catchments. Towards this attempt, in a rangeland of 5 percent slope, microcatchments were made with 5 different treatments including removed surface with gravelly filter, removed surface without gravelly filter, isolated surface with gravelly filter, isolated surface without gravelly filter and natural surface, with 5 replicates and 3 cultivars of almond (Botter Almond, Sweet Almond and Hamedani). Vegetation parameters (diameter, height, covering crown, existing and crop yield) were measured After cultivation of twigs in down part of microcatchments. The results showed that the means of variables are the lowest value in natural surface treatment and be increased in removed surface without gravelly filter, removed surface with gravelly filter, isolated surface without gravelly filter and isolated surface with gravelly filter respectively. So that in fifth year, mean values of diameter, height, covering crown, existing and crop yield in isolated surface with gravelly filter are 58. 5 mm, 258 cm, 2. 5 square meters, 1. 2 kg for each tree and 100 pecent. Also between 75 almond trees with 3 cultivars, Shahrood 21 had better growth than others. So utilization of isolated surfaces with gravelly filter can be recommended in supplying water for hillside orchards in watersheds using rainwater harvesting systems.