JOURNAL OF WATER AND SOIL RESOURCES CONSERVATION
Year:2017 | Volume:6 | Issue:2|Papers Count:10

The continued increase in demand in arid and semi-arid countries, increasing the gap between supply and demand for water in the future. Therefore, in these areas, especially in the agricultural sector an urgent need for water resources management, demand management and allocation is to avoid critical situations. The aim of this study was to evaluate the effects of increasing irrigation efficiency along with the development of cultivation on return water, and the reserves of underground water using SWAT model. SWAT model is a conceptual and half- distribution model at the basin scale that has high computational efficiency. After the simulation basin during the period 2005 to 2014 in base conditions and perform calibration and validation of model outputs, two scenarios of increased irrigation efficiency without increasing the area under cultivation and increasing irrigation efficiency along with increased cultivation was introduced to the models. Based on the results, by increase irrigation efficiency, the water used in agricultural production decreased from 330 million cubic meters per year to 186 million cubic meters per year in base conditions. Also the volume of return flow to the area decreased of 133 million cubic meters per year in base scenario to 0.22 and 1.96 million cubic meters per year in the scenario of increased irrigation efficiency without increasing the area under cultivation and increasing irrigation efficiency along with increased acreage respectively. The return of the amount of water feeding the aquifer from 29.6% in basic conditions with increasing irrigation efficiency reaches zero.

In this research, an operational simulation model was developed to indicate the importance of agricultural bore wells as an irrigation water resource and sustainable management of them to supply irrigation demand of paddy fields. The main approach of this research was based on maximum using of local water resources (e.g. wells, ponds). In the proposed model, crop evapotranspiration, irrigation requirement and interval and water head in soil and bore well are daily calculated based on input data and simulation equations. Then, using of obtained irrigation scheduling and considering the limitation of minimum permission level in bore well, water harvesting days from bore well, pumping discharge and time, pond water in fields and runoff are calculated. Simulation of groundwater level fluctuation in the out of paddy rice growing season in unsaturated condition of soil was computed by Hydrus-1D. The model was run for paddy fields of Rasht Rice Research Institute for normal year, The results indicated that 10 irrigation events were required that six and four of them were supplied by bore well and canal, respectively. The obtained results in the studied paddy fields showed that shallow groundwater level was discharged by precipitation in the out of paddy rice growing season and raised from depth of 4.85 m to 1.82 m. Therefore, operation of bore wells during paddy rice growing season as well as considering minimum permission water head does not cause considerable groundwater drawdown and unsustainable operation

Management practices and applying advanced techniques for conserving soil moisture is an appropriate way to exploit water resources. In this research, the effect of some organic wastes and a superabsorbent on soil available water and delay in permanent wilting point of a soil in steep slopes of Roodbar, Guilan province was investigated. Treatments including 10, 20 and 50% volumetric of tea waste, olive waste and municipal waste compost with the values 1, 2, 4, 8 and 16 g of a super absorbent (A200) in a completely randomized design were used in a roofed outdoor of Islamic Azad University at temperature range of 28-26oC. In order to provide moisture retention curve and determination of field capacity (FC) and wilting point (PWP) in treatments from filter paper method was used. After soil saturation, the time to reach a saturated soil to PWP was calculated. Results showed that the effect of treatments on the moisture coefficients of FC and PWP was significant at 1% level. The most significant delays in PWP coefficient (at 1% level) in 50% municipal wastes compost and 16 g/kg superabsorbent respectively with a delay of 19 and 30 days were obtained. In general, the use of agricultural wastes (10%) in combination of superabsorbent (a rate of 5 g/kg) is associated with favorable outcomes.

Investigation of precipitation characteristics is necessitate in understanding and predicting phenomena of precipitation such as runoff and flood. Therefore in this study, dependence among the main characteristics of a rainfall event (i.e., rainfall depth R, maximum rainfall depth M, wet period L, and dry period D) were modeled using D-vine structure. Firstly, different multivariate probability distributions were built, making all the permutations of the conditioning variables and then Archimedean and Elliptic copulas were used for fitting each pair-copula. The best copula family was selected for fitting on each pair-copula according to different criteria. In the next stage, M-R-D-L structure, i.e., with D conditioned by L, R by D and L, and M by R, D, and L, was known as the most suitable structure considering to AIC and BIC criteria. Finally, rainfall event characteristics were simulated using the selected structure. In order to evaluation of simulation accuracy of proposed model, the main statistics of simulated variables were compared with those of observed variables. The results showed that the majority of simulated statistics have good accordance with observed statistics.

Land use changes investigation requires the use of rapid methods and new techniques, respectively. The use of remote sensing and GIS and integrating them with accurate information and field data prepared multipurpose decision. In this study, used images of Landsat 2, sensor MSS June 1975, Landsat 7, ETM + 2002, and Landsat 8 sensor OLI June 2013, from USGS site for developing maps and survey land use changes over the period of 38 years in ENVI and ERDAS software. The Landsat 5, TM sensor image, June 1991, used to prepare land use maps and compared with 2002 and 2013, to predict land use change in 2024. Results related to land use changes in the past 38 years show a reduction of 12% (9/7060 hectare) orchard area and an increase of 7% and 5% of residential areas and agricultural lands, respectively. Also the predicted land use changes in 2024 represents a decrease of 2% compared to the current state of the orchard, while the almost constant level of agricultural land, and residential area will increase 2 percent.

Various parameters, such as rainfall, region height, evaporation rate, temperature, climate factors, drainage, topography and geology of the basin effect runoff in watersheds. Due to the interrelation of some of the mentioned parameters, their quality and effect on runoff may be different for each region. This paper presents a statistic assessment of the parameters that are effective on runoff and spatial zoning of surface water resources in central Zagross, west of Iran. The results showed a relationship between logarithmic distribution of surface runoff, and temperature and height variables with a 0.795 - 0.851 R2 coefficient of determination, applying statistical analysis and multi-variable regression method for the parameters. Considering 80 selected stations of the studying area with a correlation of 0.923, the runoff distribution in the form of discharge logarithm related to rain logarithm and height variable with confidence level of 95% showed meaningful and acceptable relation .The zoning plan was prepared through ArcGIS software on the basis of weighting effect index of each variable. The analysis of factors which affect runoff formation, and also analysis of the effect of the mentioned variables on preparing zoning plan showed tremendous movement of potentially appropriate water resources regions from south towards north and east of the studying area. Furthermore, there was approximate correspondence between hydrological parameters and determination of suitable water resources location, and statistic multi-variable regression analysis, logistic and weighting index determination of variables methods.

Direct measurement of soil moisture characteristics curve (SMC) due to spatial and temporal variation is labor and expensive. Therefore, estimation of SMC from basic soil properties which can be measured easily would be satisfactory. In this study, a dataset containing 50 particle size distributions (PSD) data of UNSODA were selected to verify parametric and nonparametric (ROSETTA model). Results indicated that SMC is easily predictable by means of PSD curve and parametric models could predict SMC more accurate than ROSETTA software. In order to determine the effect of the number of model input in prediction of SMC two methods were used, full PSD method using at least 4 mass particle frequencies, semi PSD method using sand, silt and clay percentages as a model input. Statistical analysis revealed that semi PSD method is the best fitted model to experimental data. The semi PSD method predicted SMC more accurately in comparison with other methods as a result of data independency. The predicted SMC is continuous and more reliable in drying. So the semi PSD method could be used in irrigation programming. Since, sand, silt and clay percentages are easily available soil properties and their spatial-temporal variability are approximately constant, our method can be used as an alternative to predict SMC in large scale studies.

The high amounts of losses from irrigation canals have resulted in lining the conveyance canals being as an important measure in order to increase water conveyance efficiency. The economical justification of earthen canals lining requires investigating the amount of seepage and infiltration in such canals. In this study, using a physical model and dimensional analysis, the water seepage loss from Boldaji earthen canal, Borujen city, Chaharmahal and Bakhtiari province, with loamy soil, was determined in the range of 40 to 100 liters per second flow rates. The empirical equations such as Moritz, Ingham, Molesworth and Yennidumia, Offengenden, Davis-Wilson and Indian equations were chosen for seepage estimation. Results showed that before modifying the coefficients of equations, the results of the modified Ingham have the highest correlation coefficient (0.917) with measured values. Independent variables of this method are water depth, canal length and wetted perimeter. Allocating the highest value of R2 (> 0.90) besides the lowest value of RMSE (< 3.2 liters) in comparison with measured values, after the calibration of the empirical equations for the study region and modifying their coefficients, the modified Moritz and Ingham selected as the best methods. All equations estimated the seepage loss much smaller than the measured values, which was rectified after modifying the coefficients. Utilizing dimensional analysis and transferring canal conditions to laboratory was resulted in lowering costs and less time, that according to acceptable and similar to previous studies results, it could be suggested to apply in controlled conditions of laboratory for other regions.

As a result of human activities, metal pollution has become one of the most important challenges in soil and water conservation area today. Phytoremediation utilizes plants to uptake contaminants and can potentially be used to remediate metal contaminated soils and waters. This study was carried out with the aim of assessing the ability of Acacia victoriae three months old seedlings in the accumulation of cadmium in their parts (stem and root), transfer it from the roots to the stems and to understand the effect of Cd accumulation on some morphology attributes of the plant. For this purpose, 12 seedlings of A.victoriae three months old seedlings were exposed to Cd in 4 different concentrations: 0, 10, 50 and 100 (mg/l) for period 45 days in completely randomized design with 3 replicates per treatment were considered. The results showed significantly reduction of height, biomass and resistance were observed, compared to the control plants and also symptoms of toxicity in the leafs which become thin, yellow and with brwon spots in high concentrations of Cd were notably. Also Cd accumulation in roots and aerial parts increasing trend with increasing Cd supply up to 100 (mg/l) and root tissue concentration regards to Cd concentration was higher than stem tissues concentration at all treatments. Cd were accumulated in the roots, stems and leafs of seedlings, more than 72% (19433.33 mg/kg), under 17% (4630 mg/kg) and under 11% (2853.33 mg/kg) exposed to 100 (mg/l), respectively. Bioconcentration Coefficient root and stem, Translocation Factors, Enrich Coefficient and Uptake Index were determined 184.9, 71.20, 0.39, 0.014, 7697.73 mg/kg in high concentrations of Cd, respectively. Indeed, the results confirmed that A.victoriae had the ability to accumulate Cd in the roots so that prevented Cd toxicity symptom. Generally, this desert plant can be used in the process of remediation of Cd soil polluted by way of phytostabilization.

Biochar is a durable organic compound obtained by thermal decomposition of biomass under oxygen-limited conditions (called pyrolysis). It is used for improving chemical and physical properties of soil in agriculture. The main objective of this paper was to evaluate the effects of biochar, produced from date palm’s leaves, on the physical properties and hydrological behavior of a sandy loam soil by carrying out a pot experiment. Pyrolyzed at different temperatures (300, 350, 400, 450 and 500 degree of centigrade) in an electric furnace five biochars were obtained. Biochars were in powdered form and evenly added to soil (air-dried and passed through a 2 mm sieve) at the rate of 3% (w/w) and incubated for 2 months. Water retention curves (WRCs) based on Van Genuchten model determined. By measuring gravimetric water content at field capacity (FC) and permanent wilting point (PWP), plant available water content (PAWC) calculated. Also, water holding capacity (WHC) and saturation percentage (qs) determined. The results showed that by increasing pyrolysis temperature from 300 to 500 degree of centigrade, physical properties and hydrological behavior of the soil had not significant changes. Generally, soil bulk density (BD) significantly (P<0.01) decreased compared to control, which could be attributed to low density of biochar particles and its contribution on rearrangement of soil pores and creation of new accommodation pores. WHC, PAWC, qs and FC increased 24.4%, 20.1%, 23.4% and 24% respectively compared to control, but PWP had not significant changes. Data of WRCs indicated a significant (P<0.01) increase in pores greater than 0.2 mm, which are important in storing plant available water.