mohammad taghi heydari; Hosseinali Bahrami; , alireza aliyari
Abstract
Soil moisture is one of the fundamental parameters of the environment that is directly influenced by plant life, animal and activity of micro-organisms and plays a major role in energy exchanges between air and soil. Determination of the exact amount of soil moisture content in agricultural, hydrology ...
Read More
Soil moisture is one of the fundamental parameters of the environment that is directly influenced by plant life, animal and activity of micro-organisms and plays a major role in energy exchanges between air and soil. Determination of the exact amount of soil moisture content in agricultural, hydrology and geological sciences is very important. Therefore, the use of a method that can achieve soil moisture in normal and non-corrosion conditions with high speed and accuracy is very important and fundamental. The Ground Penetrating Radar (GPR) is a non-destructive method for the subsurface investigation that is evolving and seems to be able to greatly help agriculture to identify soil and protect culture systems. Different studies have been done in the field of soil moisture determination using GPR, but in Iran, there are limited studies on the ability of this method to estimate spatial changes of soil moisture content, therefore, this research has been done with these goals. The results indicate that in the study area, the distribution of humidity at each stage of harvest shows limited changes if the time changes of humidity in the time interval between winter and spring are about 10-15% of the difference. Also, the mean square of GPR method error compared with TDR 13.2 method is also compared to the GPR and weighted 81.3 method and the correlation coefficient in these two comparisons is equal to 0.87 and 0.95, which indicates the high accuracy of the GPR method for estimating soil moisture.
hossin mosavi; mohamad kamangar; alireza karbalayy
Abstract
Understanding the behavior of phenomena requires attention to all its dimensions, and one way to understand their complexities is modeling. Soil surface moisture is a key variable for describing drought, water, and energy exchanges between Korea and the air, as well as assessing crop conditions. Soil ...
Read More
Understanding the behavior of phenomena requires attention to all its dimensions, and one way to understand their complexities is modeling. Soil surface moisture is a key variable for describing drought, water, and energy exchanges between Korea and the air, as well as assessing crop conditions. Soil moisture is affected by both environmental variables and many environmental variables such as runoff, soil erosion, and crop production, but is highly variable due to unstable spatial and temporal conditions. The purpose of this paper is to investigate, extract and evaluate the spatial model of soil moisture dispersal after more than normal rainfall in 1979-98 in Kurdistan province. In this regard, after analyzing soil moisture dispersion as dependent variable and precipitation variables, snow water equivalent, topographic moisture index and vegetation index were selected as independent variables. Then, using a general regression model (OLS) and geographically weighted regression (GWR), spatial modeling was performed. Based on the evaluation criteria, the results showed that the GWR model with R2 = 0.74 has better explanatory power and better estimation than the general regression model with R2 = 0.68. According to the results of the GWR model, snow water equivalent variable in the northern mountainous regions had the highest effect on evapotranspiration and the least effect on soil moisture. The obtained spatial model can identify low or moist soil areas in order to identify environmental potentials and improve decision making, allocation and spatial distribution of agricultural services.
Mansour Jahantigh
Abstract
Soil erosion is an important chalenge in arid and semi-arid regions which has a negative impact on soil productivity and lose soil. Improper management of natural resources causes soil erosion. This reaearch was implemented in the north of Sistan and its aim was to idintyfy the effect of sand on increased ...
Read More
Soil erosion is an important chalenge in arid and semi-arid regions which has a negative impact on soil productivity and lose soil. Improper management of natural resources causes soil erosion. This reaearch was implemented in the north of Sistan and its aim was to idintyfy the effect of sand on increased moisture in the plant root zone. For this pupose, three soil samples were collected from 0-50 cm depth and their pH, EC, C, Ca, Mg, K, Na, ESP, available phosphor, cations and texture were tested. This research had eight treatments including plant, soil and irrigation which have been done in split split-plot in four replication durig tow years. After plating a 20 cm layer of sand was applied on the soil surface in each pit. In this experiment, soil moisture was measured monthly and plant growth was measured in growing season. Statistical analysis of the data was performed using MSTAT software. Result showed that the amount of moisture was 28% higher in sand compared to other treatments at the level of 99%. According to the findings of statistical analysis on the impotance of methods used for soil moisture, the sand along with subsurface irrigation of toot had better groth at the level of 99% and were in class A and the other treatments were in class B. The conclusion was that sand causes decreasing in capillary, reducing soil evaporation, increasing moisture around root zone of the plants and water and soil conservation.
Ali Salehi; Kamran Pourmoghadam; Aliakbar Noroozi; Amir eslam Bonyad
Abstract
In recent years, a considerable part of the western oak forests of the country has been faced with drought and decline. Initial studies have identified one of the factors affecting oak forest dryness as increasing frequency and severity of dust phenomenon. In this study, the MODIS sensors with a resolution ...
Read More
In recent years, a considerable part of the western oak forests of the country has been faced with drought and decline. Initial studies have identified one of the factors affecting oak forest dryness as increasing frequency and severity of dust phenomenon. In this study, the MODIS sensors with a resolution of 1 km and 250 m and meteorological data of Kermanshah Province synoptic stations over a 15-years period (2014-2000) was used to investigate the dust phenomenon and the process of forest vegetation changes in the region. Dust intensity was investigated using visibility data and unsupervised image classification method. Also, in this study, the relationship between the occurrence of dust and vegetation changes in oak forests was investigated. Survey of dust events showed that Kermanshah Province had the highest number of dust events in 2008 and 2009, respectively. The highest incidence of severe dust was in 2012. In addition, satellite imagery and spectral indices also showed that the highest reduction of vegetation in dense forests (>50% canopy cover) by 67% and with an overall accuracy of 62% in the south and southeast of Kermanshah Province and at the border of Lorestan and Ilam provinces has happened. Results also showed that the frequency of dust phenomenon is highly correlated (70%) with the phenomenon of oak forest degradation; and dust has the effect of reducing the greenness of oak forests in Kermanshah province.
Majid Kazemzadeh; Ali Salajegheh; Arash Malekian; Abdolmajid Liaghat
Abstract
On average, 70 percent of the precipitation that reach Earth's surface, returns to the atmosphere through evapotranspiration, and this rate reaches 90 percent in arid areas. Meanwhile, watershed measures directly related to water, soil and plant, and ultimately to evapotranspiration on the natural resources ...
Read More
On average, 70 percent of the precipitation that reach Earth's surface, returns to the atmosphere through evapotranspiration, and this rate reaches 90 percent in arid areas. Meanwhile, watershed measures directly related to water, soil and plant, and ultimately to evapotranspiration on the natural resources region (ecochydrology). In this study, in order to study the effect of biological activities of watersheds (enhancement and increase of vegetation) on the process of soil moisture and evapotranspiration changes, paired watersheds of Taleghan, Alborz Province were selected. In order to calculate evapotranspiration by soil moisture balance method, soil moisture monitoring points were selected using field and laboratory studies in three main areas (northwest, eastern and southeast) and three replications and at three depths of 0-20, 40-20 and 40 -60 cm during plant growth period in 2017. Data were analyzed by ANOVA method, and Duncan test. The results showed that the actual evapotranspiration in the treated watershed and control watersheds were not statistically significant and, respectively, they showed 181 mm and 159 mm in a period of growth. In other words, the actual evapotranspiration value in the treated watershed was 14% higher than the control one during the growth period. Also, the results showed that evapotranspiration under different aspect slopes had a significant difference. The total actual evapotranspiration in the northwestern slopes were 229 and 226 mm, in east slopes were 207 and 171 and in the southeastern slopes were 109 and 80 mm in the treated and control watersheds, respectively.
Mohammad Gheitury; Mosayeb Heshmati; Mohammad Roughani
Abstract
Water resources scarcity is the negative impact of climate change, which is more severe in arid and semi-arid regions, including Iran. However, harvesting water through micro-catchment is one of the possible issues for combating this problem. This research was conducted in Kaboodeh-Olya Village to compare ...
Read More
Water resources scarcity is the negative impact of climate change, which is more severe in arid and semi-arid regions, including Iran. However, harvesting water through micro-catchment is one of the possible issues for combating this problem. This research was conducted in Kaboodeh-Olya Village to compare the effects of three different micro catchment systems on runoff harvesting and increasing soil moisture. The experimental plots were constructed at a 20% hill slope in northern direction. Research was carried out in randomized experimental block with tree replications. Micro catchments were constructed in rhomboid-shape (1.7×1.7 m) and treatments included plastic with pebble pavement (PPP), compacted surface soil with crop residue (CSCR) and control plot (CP) which was a natural surface soil. The harvested runoff from each plot was stored in a container with 100 litter capacity at the downward. The valium of overland flow was measured after each rainfall occurrence. Results demonstrated that harvested runoff rates through PPP, CSCR and CP were 88, 44 and 16 percent, respectively indicating significant effects (p<0.05) of both PPP and CSCR on runoff harvesting. Furthermore, the effective rainfall for triggering runoff at the PPP, CSCR and CP were 0.8, 1.5 and 3.4 mm that significantly was lower in PPP. Consequently, in limited CSCR building, the SSS can be used for maximum runoff harvesting and soil moisture storage.
Jahangir Porhemmat; Hadi Nazaripooya
Abstract
Infiltration is one the most important components of hydrologic cycle for utilization and managements of water resources. This phenomenon is affected by several factors and its measurement is difficult. Therefore, several models have been introduced for the simulation of infiltration. Previous studies ...
Read More
Infiltration is one the most important components of hydrologic cycle for utilization and managements of water resources. This phenomenon is affected by several factors and its measurement is difficult. Therefore, several models have been introduced for the simulation of infiltration. Previous studies in evaluation of infiltration models show that each model can be preferred over others in a specific condition. Considering this fact, six infiltration models including Philip, Horton, Green-Ampt, SCS, Kostiakov and Luise-Kostiakov and thier parameters were evaluated. Gonbad catchment in Hamedan province was selected and it was divided into four homogenous hydrologic units. Then infiltration was measured during the dry season by double ring. The results showed that Philip model was the most accurate for estimating of the infiltration and Kostiakov model is also the second one. Regression coefficients of Philip model were betwean 0.975 to one, mean error -0.017 to +0.017 and the maximum root mean square error was 0.22. Regression coefficients of Kostiakov model were between 0.956 to 0.998, mean error -9.3 to +0.003 and the maximum root mean square error was 14.25. In addition, the correlation relations between parameters of these models and two soil texture indices were carried out. The findings show that except for SCS model, the other parameters correlate with these two indices in a 5% level and at least one parameter of each model has high correlation with them. Regression coefficient for A in Philip model, B in Green-Ampt, k in Horton, b in Kostiakov and b in Luise-Kostiakov were 0.99, 0.95, 0.99, 0.999 and 0.96 respectively. Results show a lower correlation between the other parameters and the percentage of clay and sand. Based on these results, it is suggested that the regression relations of models’ parameters for different conditions of soil texture and antecedent moisture in a variety of basins should be evaluated and determined.
Majid Hosseini
Abstract
At present due to lack of proper utilization and management in non-renewable natural resources, most of the watersheds are in critical conditions. Since about 80 percent of Iran watersheds located in arid and semi-arid climatic conditions, thus addressing the issue of optimal utilization of rainfall ...
Read More
At present due to lack of proper utilization and management in non-renewable natural resources, most of the watersheds are in critical conditions. Since about 80 percent of Iran watersheds located in arid and semi-arid climatic conditions, thus addressing the issue of optimal utilization of rainfall is most important. In this research, the surface of micro catchment was isolated by plastic to increase runoff coefficient. Six treatments and three replications were considered in down part of the micro catchment. The surfaceswere prepared by available materials such as greenhouse plastic, gravel, fine and coarse sand, and for infiltration, a filter with 50 cm depth and 15 cm diameter was used. Soil moisture in 30 and 50 cm depths, was monitored by Time Domain Reflectometry (TDR). The first step eas started by cleaning grasses and compacting soil surface and monitoring 18 rainfall events. In the next step, soil surface was covered by plastic and 21 rainfall events were monitored. Results showed that the runoff coefficient increases by six to 47 percent or 7.8 times more than natural condition. The statistical analysis by T-test showed that all treatments and depths of isolated and natural conditions have significantly different results in 90 percent level of confidence. Finally, the average soil moisture content for isolated condition in comparison of natural condition is 6.4 and 9.4 percent in 50 and 30 cm of soil depth, respectively. In other hand, isolated surface increased soil moisture 3.8 and 2.8 times compared to treatments in 50 and 30 cm of soil depth, respectively.
Rahim Kazemi; Hamid Davoudi; Mohammad Jafar Soltani; Amir Sarreshtehdari
Abstract
There are more than 5.5 million date palms in Bushehr province in southern Iran. Repeated droughts and lack of irrigation water in recent years are being the most important factors for yield reduction and low quality of date fruits. Proper utilization of water supplies in order to increase water use ...
Read More
There are more than 5.5 million date palms in Bushehr province in southern Iran. Repeated droughts and lack of irrigation water in recent years are being the most important factors for yield reduction and low quality of date fruits. Proper utilization of water supplies in order to increase water use efficiency and also, identification of more tolerant plants are so sensed according to recent drought crisis in the region. Although, date palm can suffer water shortage for a long time but higher water levels and annual soil temperature between 17 to 45 centigrade degrees would make the highest production. Therefore, a study was conducted in Bushehr Agricultural Research Center to determine the responses of three date palm cultivars of Kabkab, Zahidi and Shahabi to deficit irrigation. This experiment was carried out on randomized complete block design with three replications during 2004 to 2007. The irrigation treatments of this study were water depth in four levels of 35, 50 and 65 percent of irrigation water, which shows the cumulative evaporation of class A pan. Irrigation water was offered to plants under pressured system. Tree responses were evaluated in each year for the following properties: fruits and seeds weight, length and diameter, pulp to seed ratio, TSS, pH and yield. Results showed that cultivar effect was significant in all date palm responses (p>0.01) which can prove different inherent qualitative and quantitative characteristics in date palm cultivars. Zahidi cultivar proved to have higher water use efficiency in water stress conditions during drought periods. Irrigation treatments affected only the yield responses. Although, 65 percent of irrigation water showed to have higher production abut it was classified in the same statistical class with 50 percent of irrigation water. This means that in the situation of water shortage, 50 percent of irrigation water would be the choice. Also, mean water usage during three years of the experiment were 5497, 7758 and 9822 m3 ha-1 per year in the irrigation treatments with 0.544, 0.481 and 0.409 kg m-3 water use efficiency respectively. The sequence of water stress toleration in three date palms was Zahidi > Shahabi > Kabkab.
Mahmood Izadi1; Morteza Pouzesh Shirazi
Abstract
There are more than 5.5 million date palms in Bushehr province in southern Iran. Repeated droughts and lack of irrigation water in recent years are being the most important factors for yield reduction and low quality of date fruits. Proper utilization of water supplies in order to increase water use ...
Read More
There are more than 5.5 million date palms in Bushehr province in southern Iran. Repeated droughts and lack of irrigation water in recent years are being the most important factors for yield reduction and low quality of date fruits. Proper utilization of water supplies in order to increase water use efficiency and also, identification of more tolerant plants are so sensed according to recent drought crisis in the region. Although, date palm can suffer water shortage for a long time but higher water levels and annual soil temperature between 17 to 45 centigrade degrees would make the highest production. Therefore, a study was conducted in Bushehr Agricultural Research Center to determine the responses of three date palm cultivars of Kabkab, Zahidi and Shahabi to deficit irrigation. This experiment was carried out on randomized complete block design with three replications during 2004 to 2007. The irrigation treatments of this study were water depth in four levels of 35, 50 and 65 percent of irrigation water, which shows the cumulative evaporation of class A pan. Irrigation water was offered to plants under pressured system. Tree responses were evaluated in each year for the following properties: fruits and seeds weight, length and diameter, pulp to seed ratio, TSS, pH and yield. Results showed that cultivar effect was significant in all date palm responses (p>0.01) which can prove different inherent qualitative and quantitative characteristics in date palm cultivars. Zahidi cultivar proved to have higher water use efficiency in water stress conditions during drought periods. Irrigation treatments affected only the yield responses. Although, 65 percent of irrigation water showed to have higher production abut it was classified in the same statistical class with 50 percent of irrigation water. This means that in the situation of water shortage, 50 percent of irrigation water would be the choice. Also, mean water usage during three years of the experiment were 5497, 7758 and 9822 m3 ha-1 per year in the irrigation treatments with 0.544, 0.481 and 0.409 kg m-3 water use efficiency respectively. The sequence of water stress toleration in three date palms was Zahidi > Shahabi > Kabkab.
