مجله سامانه های سطوح آبگیر باران
سال پنجم شماره 1 (پیاپی 14، بهار 1396)

Forest and its soil play an important role on sustainable live, while most of them are suffering from climate change driven dieback phenomenon, particularly in the Zagros forest. Consequently, runoff harvesting through short-term measures is necessary for curtailing severity of forest mortality. This research was conducted in the Kalezard forest, Kermanshah, Iran to evaluate the effects of crescent shaped bounds on enhancement of soil organic carbon (SOC) and reduction of forest tree dieback. The treatments include a Crescent Shaped Bound Preservation (CSB), Preservation treatment (PT), Crescent Shaped Bound without Preservation CSB-P and Control treatment (CT), resulting in a total of 12 plots. Each plot measured 50×30 meters performed in September 2012. Soil moisture was measured in three layers (10, 30 and 50 cm) using time domain reflectometry (TDR). Finally all data statistically were analyzed using SAS6.12 software. Results revealed that in first year was 2.33, 2.40, 1.90 and 1.95 % in CSB,PT, CSB-P and CT, respectively and indicating no significant differences among them. However, after three years, the respective level of SOC was 3.24, 2.90, 2.10 and 1.70 percent demonstrating significant increase (p

The purpose of this research is to study the effect of the turkey nest on soil characteristics in arid regions. In order to carry out this work, the structural status of the turkey nests was studied. Four soil samples were taken from the control and four samples were selected from the inside of the turkey nests as well. Texture features, calcium, sodium, magnesium, soluble sodium percent, sodium absorption ratio, acidity, electrical conductivity were measured and the results were analyzed descriptively in order to investigate the performance of the structures regarding the soil improvement and soil regeneration and to determine its physical and chemical characteristics. The results of the analysis of the physical properties of soil samples show that the sand percentage of the turkey nest treatment decreased by 184% compared to the control, and clay and silt increased by 10% and 62.5%, respectively. Investigating the chemical properties of the soil also suggests that the acidity of the turkey nest soil samples has increased slightly and the electrical conductivity (EC) decreased by 239.3%. Also, the amount of calcium cations, magnesium cations and sodium decreased by 210, 102 and 131%, respectively, in the soil of the turkey nest samples compared to the control.

The lack of stored soil moisture due to the reduction of rainfall and runoff during the growing season as well as inappropriate distribution of the rainfall is an important factor that affects the establishment of vegetation cover and the production of the plant species. Hence, the application of integrated methods for appropriate and optimized use of the rainfall provides suitable conditions to irrigate dry land gardens, especially in cases that the intensity and duration of the rainfall do not result in suitable runoff. The study of vegetation cover and dry land gardens on the southern hillside of Oun Ibn Ali showed that precipitation and runoff reduction are one of the most important factors preventing the development of vegetation cover and dry land gardens in this area. This present research intends to provide the soil moisture content required for plant species in the region via the optimized use of the rainfall and help to solve this problem. The statistical model of this research was performed in the form of a randomized complete block design with three treatments. The first treatment was control treatment (A), which consists of Buckthorn tree (as a resistant plant to water scarcity and widely used plant in the mountain environment), soil of pit and rotting animal manure as 25 % of the whole of the pit. The second treatment (B) was water harvesting insulator surface system accompanied with Pomis at the end of the system. Water harvesting insulator surface system without Pomis at the end of the system was the third treatment (C). The research was performed during 2011 to 2013 in the Oun Ibn Ali region. The dimensions and shape of plots were 7*5 and rectangle. In addition, they were built on a slope about 30%. The height, collar diameter and leaf area were taken from Oleaster (Elaeagnus angustifolia) trees and soil moisture was also measured using a TDR device during the execution of the research. In this plan, the selection of Elaeagnus angustifolia is due to its resistance to drought and the use of this plant in the vegetation cover of Oun Ibn Ali. The results showed that the use of these treatments increased the soil moisture statistically significant at1 and 5 percent compared to control treatment. Comparing the volumetric moisture average of two years revealed that water harvesting insulator surface system accompanied with Pomis at the end of the system treatment had the maximum stored moisture and without Pomis and control treatments were observed in the next order, respectively. Moreover, the effect of the experimental treatments on the height, collar diameter and leaf area of Oleaster tree was significant at 1 %. The maximum and minimum of the height, collar diameter and leaf area belong to water harvesting insulator surface system accompanied with Pomis at the end of the system and control treatments, respectively. Therefore, it is recommended to use this method to create green space in this area.

The storm events are one of the most devastating natural disasters that have imposed many damages to human communities during the course of history. The various air masses cover Guilan Province and each one of them impose seasonal and sever rainfalls on the province. As a result, the water level rises and the occurrence of the floods is indispensable. According to the statistics and documents during the recent decades, huge floods have been occurred in the province, leading to death and economical damages. The synoptic patterns of atmospheric conditions in the region control these types of phenomena. The synoptic maps, at different levels of the atmosphere, can be monitored. Many of the earth's surface phenomena, such as floods, droughts, frost, etc., can be identified through the synoptic maps. One of them is the amount of rainfall available to each region, which can be determined by studying the synoptic maps. Moreover, One of the most important factors leading to occurrence of flood is weather phenomena, such as intense cloudbursts and rainfalls. Climate study and identification of weather phenomena, especially the cloudbursts have an important role in forecasting the floods and making flood warning plans. Therefore, this research has been conducted in order to analysis the the cloudbursts leading to flood in west of Guilan Province. For this purpose, statistics of floods and local cloudbursts related to each flood in west region of Guilan were identified and drawn out since 2001 to 2011. Accordingly, during this period 13 floods and local cloudbursts were identified. In the next stage, serological isobar plans for the sea level of 1000 m and geopotential of 500 Hectopascal for pre–rainfall days and rainfall day were obtained from NOAA and each of them was observed using isometropia analysis method consistently analyzed using the GrADS software for mapping required at the ground level. The results showed that there were 7 weather patterns effective in the formation of these rain storms. Among the seven models of high-pressure, the Scandinavian and Mediterranean systems were the most affecting systems on the flooding and flood events in the western rivers. In addition, the rain storms have been caused by the presence of at least one high-pressure system.

In this research, we tried to determine the input composition and model for estimation of precipitation in Shahrood. To achieve this objective, monthly weather data including evaporation, temperature, relative humidity, solar radiation, wind speed during the period of 1963 to 1915, and artificial neural network and support vector machines have been used. 75% of the data was used for calibration and 25% for validation of the models. In this research, an artificial neural network of laminated perceptron with a sigmoid tangent function and 1 to 30 neurons in the hidden layer was used and a support vector machine model with radial base kernel function was used to estimate rainfall in Shahrood district. The performance of each model was evaluated using the statistical mean square error and correlation coefficient. The uncertainty of the models was also determined for two parameters, d-factor and p-factor. Considering that both models have good performance in rainfall estimation, the support vector machine model with less error and uncertainty than artificial neural network model has better performance in predicting rainfall in Shahrood. Therefore, a support vector machine model can be used as a very suitable model for precipitation estimation.

In this research paid attention to investigate cloudiness in Mashhad plain, based on the meteorological yearbook (1986-2008 that the most frequent overcast occurrence has been shown. Then we studied the prevalence of low and medium height clouds and average of them in each month¡ from Mashhad synoptic station data during 2001-2010¡ considering to the importance of medium and low clouds in the cloudseeding process¡ and was paid to review condition of sky with low clouds. We investigate to the formation of low height clouds with vertical development¡ including cumulus (type 2) and cumulonimbus¡ in this region, given the importance of this clouds. The investigation of these cloud formations showed the most cloudiness has been occurred during cold and rainy seasons i.e. winter and early spring. The evaluation of the cloud base temperature and the level of freezing in this region has been done according charts and data of Mashhad station and using skewt with rainfall and without rainfall during 1992-2011. The basis of information has been obtained on the basis of overcast condition and the average of the cloud base temperature Some instability indexes (K, Showalter, Precipitable water, CAPE) was obtained in rainy days at 00Z, using data of Wyoming university website, during 1992-2011. Then was paid to investigate the correlation between instability index (K Index¡ Showalter Index, Precipitable water and CAPE Index) with 6 hours rainfall (from 00 to 06 Z). The studies showed a correlation is positive and significant at 1% between precipitable water, K index with cumulative 6-hour precipitation. According to the correlation and significance level, the Sowalter index and CAPE index can’t be used in determining the appropriate threshold of cloudseeding. the data showed a very high scattering.

The performance of any water projects depends on forecasting hydrological events in the future. In hydrology using physical models is not feasible to predict future events and often used from abstract model that describes the system based on mathematical concepts. The use of statistical distributions to estimate annual average discharge in different return periods to design the hydraulic structures is one of the most common methods. In this research in order to obtain the best statistical distributions and estimate annual average discharge in different return periods, annual average discharge data from 6 hydrometric stations Gilan province named Punel, Rudbarsera, Toollat, Shalman, Mashinkhaneh and Haratbar were collected during the 50-year statistical periods (1965 to 2016). The randomness of the data was tested with Run Test method and then fitted with a variety of relevant statistical distributions using SMADA software based on the Method of Moments. Finally, the best distribution was determined using statistical indicators root mean square error (RMSE) and mean absolute error percentage (MAPE) for all hydrometric stations. The results showed that the mean annual discharge statistics of Punel, Shalman, Toollat, Mashinkhaneh and Haratbar stations with Log Pearson type III distribution and Rudbarsera station with 3Parameter Log Normal distribution Show the most fit and compliance. Therefore, using the best distributions mentioned above, return periods of 2, 3, 5, 10, 25, 50, 100 and 200 years were estimated.