نشریه علوم آب و خاک (علوم و فنون کشاورزی و منابع طبیعی)
سال نوزدهم شماره 2 (پیاپی 72، تابستان 1394)

Potassium (K) is an important cation in saline soils of arid lands، and its content، distribution and availability may be affected by native plants. To study the effect of halophyte species on different K forms in Korsia region located in western Darab (Fars province)، three dominant halophyte species including Juncus gerardi، Halocnemum strobilaceum، and Salsola rigida were selected. Sampling was done from soils in canopy and between plants at the depth of 0-15 (surface) and 15-30 cm (subsurface) in triplicate. Soil physical and chemical properties including soil texture، organic matter، calcium carbonate، pH، cation exchange capacity، saturation percentage and electrical conductivity and different K forms including soluble، exchangeable and non-exchangeable were determined. Results indicated that organic matter، CEC، pH، and EC were affected by plant species. Juncus gerardi increased exchangeable K and decreased soluble K، but it had no effect on non-exchangeable and HNO3-extractable K. Halocnemum strobilaceum significantly increased soluble، exchangeable and HNO3-extractable K in surface and subsurface soils rather than soils between plants. This finding may be due to K uptake by plants from subsoils and also transfer of soluble K from soils between plants to roots. Salsola rigida had no effect on K status. Generally، soils between plants had more soluble and exchangeable K in surface than subsurface horizon. The studied halophyte species showed differences in growth and development pattern، soluble salts and K absorption and secretion، grazing by livestock، returned organic matter to soil، soluble salts and K reserves in their organs، and water uptake and thereby water and K diffusion from soil far from rhizosphere to roots، which may have different effects on K distribution in soils. Juncus gerardi، as regards effects on decreasing salinity and soluble K and increasing exchangeable K، may be recommended as a suitable species for remediation of the studied soils.

The SIMDualKc model is an irrigation scheduling simulation model that uses dual crop coefficient method for estimating ETc by computing two separate soil water balances in daily time-step, one for the soil evaporation layer from which Ke is computed, and the other one for the entire root zone to compute the actual Kcb adjusted to the soil moisture conditions. In this study, lysimetric measurements of evapotranspiration rates relative to (Coriandrum sativum L.) during 2 years were used for model calibration and validation. Kcb values for coriandrum were found as 0.21 for the initial, 1.12 for the mid-season and 0.79 at harvesting period. Model results have shown a good agreement between the actual daily evapotranspiration predicted by the model and the ones resulting in water balance calculation on drainable lysimeters, and root mean square errors of estimates (RMSE) of about 1.64 mm and 1.53 mm for the calibration and validation, respectively.The modeling efficiency EF and the index of agreement dIA were equal to 0.8 and 0.93, respectively, thus indicating good performance of modeling with SIMDualKc. Model estimates of evaporation (E) for validation and calibration years displayed an average of 181 mm, representing 25% of ETc. In conclusion, results show that the model is appropriate to simulate the daily evapotranspiration adopting the dual Kc approach for coriandrum in west regions of Iran.

Urmia Lake, located in north-west of Iran, has been exposed to various threats such as drought, construction of dams, land use changes and increased global temperature. Due to the importance of Urmia Lake, it is feasible to conduct different kinds of studies to identify the problems of its watershed. The main objective of this study was to evaluate SWAT program’s ability to simulate runoff in Urmia Lake watershed with an area of 52000 km2. The model was run for the 1980-1997 period. Calibration and validation periods were from 1980 to 1991 and from 1992 to 1997, respectively. The results of calibration for 10% and 85% of hydrometric stations were very good and suitable, respectively. Also, validation results for 25% and 45% of hydrometric stations were very good and suitable, respectively. These results show the high ability of SWAT model to simulate discharges in Urmia Lake watershed. Moreover, some factors influencing inflow to the lake in recent years were evaluated. The outcomes revealed that recent changes (dam cconstructions, climate change and land use change) in the watershed have caused inflow volume to the lake to decrease by 80%. So, if natural management conditions had prevailed in the watershed, the Lake’s conditions would have been much better.

Land use classification and mapping mostly use remotely sensed data. During the past decades, several advanced classification methods such as neural network and support vector machine (SVM) have been developed. In the present study, Landsat TM images with 30m spatial resolution were used to classify land uses through two classification methods including support vector machine and neural network. The results showed that SVM and neural network with the total accuracy of 90.67 % and 91.67% are superior. SVM had a better performance in separating classes with similar spectral profiles. In addition, SVM showed a better performance in delineating class borders in comparison with neural network method. In summary, both SVM and neural network showed satisfactory results but the method of support vector machine proved better with a difference of 1% and 2% in overall accuracy and kappa coefficient, respectively. This was an expected outcome because SVMs are designed to locate an optimal separating hyperplane, while ANNs may not be able to locate this separating hyperplane.

Land use is one of the basic factors for controlling the hydrologic behavior of watersheds. Therefore, it is generally assumed that land use change is the cause of variation in hydrological dynamic of watersheds. In this paper, the land use effect in present and optimum conditions on sedimentation of watershed was studied using GIS and applying the HEC-HM model in Shoor-Shirin watershed in Fars province. Land use map was provided based on curve number map, and this map was considered as the important factor for HEC-HM model. The results showed that the estimated sediments in two different conditions were completely different. In fact, the estimated sediment in the optimum condition was 12% less than the current land use. This means that land use change and land use type play important roles in decreasing or increasing the peak flow and erosion.

One of the major problems associated with petroleum-contaminated soils is water repellency, especially in arid regions of the world. Hence, a variety of methods such as clay addition has been proposed to improve the hydrophobicity of soils. This research was conducted to evaluate the influence of zeolite application on water repellency of an oil-contaminated soil from Khuzestan Province under various treatments including initial soil moisture content (0, 10, 20, and 30 weight %), the amount of applied zeolite (2, 4 and 8 weight %), size (25-53 and <2 μm), and exchangeable cation (Sodium and Calcium). The hydrophobicity of soil sample was determined using Water Drop Penetration Time (WDPT) method. The results showed that by increasing the amount of applied mineral WDPT decreased, where the application of 2 percent of zeolite led to the reduction of WDPT by about 27 percent less than the control. The results also indicated that soils treated with sodium-saturated zeolite had less WDPT than the calcium-treated samples, where the average of WDPT in sodium and calcium treatments decreased by 23% and 5% compared with the control, respectively. The initial moisture content of 30 percent showed the best performance with the decreasing WDPT of about 67 percent. Furthermore, the effect of mineral particle sizes showed a meaningless reduction in WDPT.

Soil pollution and accumulation of heavy metals in soils and crops are the most important bioenvironmental problems that threaten the life of plants, animals and humans. This study was conducted to explore contamination of heavy metals in soils of Hamadan province. A total of 286 composite surface soil samples (0-20 cm) were collected thoroughout the province. After preparation of the samples, the total contents of Zn, Pb, Cu, and Ni in soil samples were extracted using HNO3. Total contents of heavy metals were measured by ICP. Contamination factor results showed that most samples were moderately polluted and contamination factor for lead was highly polluted. Interpolated distribution map of contamination factors (CF) and pollution load index (PLI) of the heavy metals were prepared using GIS. The overlap of CF and PLI maps with geology and land use maps indicated that the concentrations of Ni, Pb, Zn, and Cu have been controlled by natural factors such as parent material, but agricultural activities according to excessive consumption of animal manure and chemical fertilizers can increase most of these elements in soil.

Vis-NIR spectroscopy has been introduced as a non-destructive, fast, and cheap technique, with minimal sample preparation and no loss or damage to the environment. No investigation has yet been carried out to examine the ability of this method to estimate soil properties in Iran. The objective of this research was to investigate the capability of Vis-NIR spectroscopy to predict the amount of organic matter, carbonate and gypsum in surface soils of Isfahan province. A total of 248 surface soil samples were collected from the study area. Soil organic matter content, gypsum and carbonates percentages were measured by standard laboratory methods. Soil spectral analyses were performed by a field spectrometer using 350-2500 nm wavelength range. Different pre-processing methods were evaluated after recording the spectra. Partial least squares regression was used to predict soil parameters. R2 values for organic matter, carbonates and gypsum were 0.61, 0.45 and 0.8, respectively. Based on RPD (Ratio of Prediction to Deviation) values, the precision of prediction model for gypsum was quite good, and acceptable for organic matter, whereas the prediction of the model for soil carbonates was poor. Consequently, vis-NIR spectroscopy is capable of predicting some soil properties simultaneously and the model accuracy is acceptable.

Considering soil compaction problem in sugarcane fields due to using heavy harvester and haulout equipment under unsuitable moisture conditions, this research aims to assess soil compaction in sugarcane fields located in DabalKhazaei Plantation unitofSugarcane Development and By-product Company, Ahvaz. Undisturbed soil samples from the furrow (wheel tracks) were collected for measuring soil water content and bulk density. Considering the changes in soil texture of sugarcane fields, for expressing the degree of soilcompactness, in addition to soil bulk density (BD), relative bulk density (BD divided by reference BD) was also determined. The change in soil mechanical resistance with depth was determined by a cone penetrometer. Results showed that most of soil BD values measured in the sugarcane fields were in the range of small root development scale (high limitation). Comparingthe calculated RBD values with optimum value (0.85), it was observed that most of the values were higher than the optimum values recommended for root growth. This shows excessivesoil compaction in the sugarcane fields. The values of cone indices measured in soil profiles indicated that most of the values were higher than either limiting (2 MPa) or critical (3 MPa) values for root growth. Therefore, for improving soil physical fertility and achieving sustainability in crop production, management of farm machinery traffic in sugarcane fields, especially at the harvest time, needs to be reconsidered.

Transporting borrow materials for proper infrastructure of water channels to bear the load of such structures is important in the development plans. Therefore, in this research clay nanocomposite material with a weight ratio of %1 was added to the soil. Soil sample was taken from the bed of the C25 canal (distributary of GanjAfrooz diversion dam within Alborz project area) at various intervals and the depth of 1 meter. Unconfined compression strength and consolidation tests were performed on the selected soil. The results showed that the addition of nanoclay to the soil increased the rate of shear resistance, cohesion property and compressibility of soil, respectively, equal to 14.13, 14.13and 82.76 percent. Also, angle of failure and ultimate void ratio decreased. As a result, the addition of nanoclay to the soil makes soil strength and stability greater and there are no problems caused by bed erosion and transporting of borrow material for infrastructure of channel.

Sediment yield of watersheds results from different erosional and hydrological processes which make it too complicated to be predicted. Awareness of runoff and sediment yield regimes is useful to better understand the erosional condition of watersheds for management. Therefore, determination of factors controlling hydro-sedimentary response of watersheds is very necessary. For this purpose, ground surveying and measurements of hydrograph and sediment graph were carried out in the representative basin of Khamsan in the uplands of Gavshan dam during 9 months. Finally, relationships between runoff and sediment yield were obtained, then corresponding runoff-sediment events were analyzed. Results showed that 5 events out of 6 occurring runoff events had eight-shaped hysteresis loop and only one event showed clock-wise hysteresis loop. Among them, the highest and lowest flood discharges were attributed to the events of 02.11.2010 and 05.01.2011 with 151488 M3 and 11764.8 M3 Run off, respectively. The study also showed that for this watershed no specific type of loop existed for a particular season. Accordingly, the seasonal patterns could not be attributed to a particular type of loop. Precipitation and runoff characteristics may have also played a role in addition to other factors. Results emphasize the importance of rainfall distribution and rising-falling limbs of hydrograph for the corresponding hysteresis loops in small watersheds.

Humic substances are the most important organic fractions in soils and have affinity towards trace metals. In order to evaluate the effect of humic acid on zinc (Zn) sorption and desorption by soil,‌ a batch experiment was conducted with two soil samples which were different in clay and calcium carbonate contents. Three levels of humic acid (0,‌ 200, 500 mg/L) and various Zn concentrations (0 to 450 mg/‌L) were applied at constant ionic strength (0.05 M NaCl). Adsorption data were fitted to Langmuir, Freundlich and Temkin equations. Freundlich equation fitted relatively better (R2= 0.86-0.98). Results showed that the application ofhumic acid increased both ‌sorption and desorption of Zn in the two sample soils. Increasing of humic acid concentration increased maximum adsorption of Langmuir (qmax) up to 8-21% and Freundlich sorption capacity (Kf) up to 73-95%.‌ All sorption parameters including‌ Langmuir binding energy (KL), Freundlich intensity factor (n) and coefficients of Temkin equation (A, KT) were increased by adding humic acid, so that the above mentioned sorption parameters of S1 (with low clay and calcium carbonate) were lower than those of S2 (with high clay and calcium carbonate). Application ‌of humic acid (500 mg/L) increased desorption of Zn (DTPA-Zn) ‌from 511 to 711 mg/kg for S1 and 499 to 609 for S2‌.

Fluoride (F) is an essential element for humans and animals. The continuous ingestion of fluoride by humans and animals in excessive amounts has damaging effects. The objective of this study was to investigate the uptake of fluoride in spinach and alfalfa in an alkaline soil of Isfahan, Iran. Two plants were planted in lysimeters at Isfahan University of Technology research station site. The treatments consisted of two plants and three concentrations of F. Each treatment was performed in triplicate. All the plants were harvested after 125 days and the total plant's F concentrations were determined. The F concentration in both plant's roots were higher significantly (p<0.05) than the plant's shoots at both treatments. The F concentration in spinach root was 2.5 to 3 times greater than those values in alfalfa root. Totally, the RCFs and SCFs values of F were very low. This showed that these plants did not uptake much fluoride from the soil.

Spatial and temporal distribution of dust deposition rate (DDR) in Isfahan city and the influencing climatic parameters were studied. Dust samples were collected using glass trays placed on the roof of one-story buildings from 20 sites in Isfahan city for 12 months. Climatic data were obtained from Meteorological Organization and analyzed. The highest and the lowest amount of DDR in agreement with the direction of prevailing wind were observed for dry months with eastern and northeastern wind directions and wet periods with western and southwestern wind directions, respectively. This can indicate dust emission from the desert located in eastern part of Isfahan city. Statistically significant inverse correlation between DDR and precipitation and relative humidity, and significant and positive correlation of DDR with Min and Max temperatures in all the studied months and also with Max and average wind speed for dry sampling months may well justify the temporal distribution of DDR in the city. In dry months, finer particles from eastern desert can be transported a longer distance and deposited in the western part of the city, far from the source area. In wet seasons, however, soil aggregates become coarser as a result of particle adhesion. This, in turn, results in the deposition of dust near the source area as the transporting power of dust reduces.

The present study was conducted to increase phytoextraction efficiency of Festuca ovina L. in lead contaminated soil in the EDTA-assisted (0, 1.5, 3, 1.5+1.5, 3+3, 6 mmol kg−1), assess the best time of plant harvesting to increase Pb uptake and method of EDTA application to reduce Pb leaching risk. The results revealed that the greatest Pb uptake was observed in 3EDTA treatment. Therefore, 3mmolkg-1 was used in the second step for assessing harvest time for 15, 30 and 45 days. Results showed that the concentration of Pb in plant tissues was increased with the passage of time and the best harvest time to achieve maximum removal of Pb was 60 days of the first harvest. In the third step to reduce leaching of Pb-chelate, 3mmolkg-1 EDTA in five ways of single, double, triple, quadruplet, quintuplet were added to the soil. The results indicated that under quintuplet application, Pb content reached its minimum concentration in the soil and in the plant organs, the Pb concentration was maximum and metal concentration in the plant organs did not vary significantly when triple, quadruplet and quintuplet dosages were added (p<5%). Overall, optimum phytoextraction of F. ovina L. and Pb leaching reduction were achieved when 3mmol kg−1 EDTA was added in quintuplet dosage and the plant was harvested at the end of growth stage.

The common method of puddling is using a conventional tiller which requires long time of soil operations.In this study, the effects of tillage equipment on moisture characteristic curve of a paddy soil were investigated. The treatments included tillage equipment (T1: conventional tiller, T2: rotary puddler, T3: cone puddler, T4: tractor mounted rotivator) and number of puddlings (P1: puddling once, P2: puddling twice, P3: three timespuddling and P4: four timespuddling). The results showed that at saturation point, tractor mounted rotivator presented the highest moisture content. At field capacity and permanent wilting point, the cone puddler showed the highest moisture value. The two newly made units held more moisture and saved water. In different tillage equipment, increasing the number of puddling reduced soil moisture. Available moisture in the soil without tillage (control) was less than in soils under rotary puddler and cone puddler.

Consequences of heavy metal accumulation in soils are of great concern. One way of decontaminating heavy metals from soils is using chelating agents, particularly EDTA. In this research, three contaminated soils (with total concentration of these metals of 10.5, 55.8 and 80.6 mmol kg-1) were collected from the surface layer of the lands surrounding a zinc-lead smelting plant in Zanjan province. The extent of Zn, Pb and Cd release by Na2H2EDTA (100 mmol kg-1 of dry soil) from these soils in column leaching experiments (both continuous and pulse addition methods) assembled into half of saturated hydraulic conductivity was assessed. In preliminary experiments, the leaching was stopped due to a drop in hydraulic conductivity. Therefore, the continuous addition method was performed with calcium nitrate as the background solution and the pulse addition method was conducted using this background solution coupled with pH adjustment to 8. Based on the results, the percentage removal of Cd as well as Pb was relatively the same for the two addition methods while the removal of Zn was 13% on average higher in the continuous addition method than in the pulse addition method. For both methods, the removal efficiencies followed the order of complex stability constants (as Pb>Zn>Cd) in a limited concentration range of EDTA to complex heavy metals. Furthermore, in contrast to Cd and Pb, a direct linear relationship was found between the percentage removal of Pb and its total amount in the soils. Surprisingly, the Pb concentration was on average only about one-twentieth of the Zn concentration. The breakthrough curves of both methods showed the mobility order of Cd>Zn>Pb. In general, it seems that the removal pattern of soil heavy metals is dependent not only on the soil type but also on the removal method.

Transport of fluoride and consumption of groundwater with excess fluoride concentrations poses a health threat to millions of people around the world. The objective of this study was to simulate transport of fluoride (F) using HYDRUS-1D model. The study was conducted in lysimeters at Lavark research station site in Isfahan. The treatments consisted of two concentrations of F (157 and 315 mg kg-1). The duration of the study was 125 days. Some of soil physical and chemical properties, soluble F and total F concentration were determined during the study. The results showed the transport of F in calcareous soil profiles. This may be due to the high pH and desorption of F ion as a result of repulsion by the more negatively charged soil surfaces. The highest concentration of total F and water soluble F were observed in the 10 cm surface soil layer. The concentration of F decreased with increased soil depth. The correlation coefficient was significant between the water soluble fluoride and the total fluoride (1% level). Also, the difference between the observed t- value and a critical value on the t distribution is statistically insignificant. It showed that the model simulated successfully water soluble F concentration in the soil profile.

Since the development of surface water control needs accurate access to flow behavior of sediment rates, the lack of sediment measurement stations, the novelty of most stations and the lack of statistics on the deposit make it difficult to properly evaluate and simulate the flow behavior and their sediments. In a watershed, the morphological characteristics and sediment load of flow affect each other. It is, thus, important to know about the extent of this relationship to manage and control the flow in downstream areas. In the present study, using artificial neural networks and sediment rating regression methods based on the data from 136 events and also morphological parameters, we have attempted to predict the sediment load of Bagh Abbas basin. In the first step, we used flow data to predict the sediment load of both methods, and then basin morphological characteristics such as the compactness factor and form factor were added to the models. The results of this study showed that by using neural networks of Multilayer Perceptron (MLP) type with Levenberg – Marquardt algorithm and the stimulation function of tangent Sigmoid with two hidden layers and four neurons in each layer, we can predict suspended sediment discharge rate with a sufficient accuracy. Accuracy of the results obtained from the ANN method was higher than the accuracy of rating curve method. In the evaluation of NGANN & GANN network methods and SRC & MARS regression methods, correlation coefficients were respectively calculated as 0.94, 0.93, 0.767, 0.766, and root mean square errors (RMSE), 0.45, 0.49, 2.3 and 2.3. Nash coefficient (NS) was calculated respectively as 0.71, 0.58, 0.27 and 0.23. Therefore, the most efficient method among the four models is artificial neural network combined with morphological data (GANN). Furthermore, the findings of the study show that adding geomorphological parameters to sediment rating has little effect on the model performance.

The present study was conducted in order to investigate the effects of silicon and salinity on growth, chemical composition and physiological properties of rice var. Hashemi, in the greenhouse of agricultural college of University of Tabriz during 2011. It was arranged as factorial based on a completely randomized design with three factors consisting of silicon at four levels (control, 100, 200 and 300 mg/kg soil), salinity at four levels (control, 2, 4 and 8 dS/m) and source of salinity at two levels (NaCl and combination of different salts) with three replications. The results showed that increasing soil salinity resulted in a decrease in shoot dry weight, catalase activity and concentrations of phosphorus, potassium and reducing sugars, and an increase in glycine betaine content in the plants. The comparison between two sources of salinity also revealed that plants treated with a combination of salts experienced less vigorous decrease in dry weight and potassium, and reducing sugar's concentrations. Meanwhile, the enhancement in glycine betaine content appeared to be less intense in these plants. Hence, it could be concluded that the salinity resulting from a combination of different salts caused less damage to plants than NaCl salinity. Silicon supplementation resulted in increasing of shoot dry weight, catalase activity and concentrations of reducing sugars, glycine betaine, phosphorus and potassium. Therefore, silicon nutrition alleviated suppression effects resulting from the presence of soil salts, which means, enhanced the salt tolerance of rice.

Erosion and sedimentation as a river natural behavior lead to the loss of soil and cause irreparable damages to water development projects. Since the phenomenon of erosion and deposition is one of the most complex natural processes, the complete understanding of the effective factors involved in this phenomenon is really a big problem. This study was done to optimize the parameters affecting sediment yield and determine their sensitivity in the Doiraj river basin in the West of Iran, using SWAT, a semi-distributed model, and SUFI2 algorithm, and the monthly sediment yield from 1994 to 2004. In the first run of the model, coefficients R2, NS, and Br2 were respectively obtained as 0.43, 0.39 and 0.28. The results showed that performance of the model with the default data was not satisfactory and we needed to determine the used optimal values. Then, the optimal values of parameters were determined using SUFI2 algorithm and reverse modeling and the model was run with the new values. Based on the new results, coefficients R2, NS, and Br2 were respectively obtained as 0.75, 0.73 and 0.65 and performance of the model improved and its accuracy increased acceptably. In the next step, from among the studied 30 parameters, (CH_N2), (USLE_K), (USLE_P) and (OV_N) were identified as the important parameters effective in the output of the sediment yield from basin. Also, USLE_K as was diagnosed as the most sensitive parameter. Results of this survey can be used in the management of the effective parameters in sediment load. Determining exact values of the effective parameters in other studies can be helpful to improve the simulation results in similar basins, too.

One of the major challenges in water resources management is the operation of trans boundary watershed. This has been experienced in case of Helmand River between Iran and Afghanistan since the last century. For such a situation, application of a conceptual rainfall-runoff models that can simulate management scenarios is a relevant tool. The SWAT model can be a relevant option in this regard. However, the required hydro-climatic data for them is a serious obstacle. Especially, this problem gets exacerbated in the case of Afghanistan with poor infrastructures. So, application of this type of model would be more problematic. This paper aims to investigate capabilities of SWAT for the simulation of rainfall-runoff processes in such a data-scarce region and the upper catchment of Helmand River is used as the case study. For this purpose, discharge data of Dehraut station from 1969 to 1979 along with some metrological data were prepared and used to calibrate and validate the simulations. The results were acceptable and the coefficients of determinations (R2) during calibration and validation periods were 0.76 and 0.70, respectively. Notably, with respect to snowy condition of the basin, the elevation band option of the snow module of model had a significant effect on the results, especially in the base flows. Moreover, two Landsat satellite images during February 1973 and 1977 when the basin was partly covered with snow was prepared and compared with the SWAT outputs. Similarly, the results showed good performance of the model such that R2 were 0.87 and 0.82, respectively.

Determination of relationships between different forms of potassium in soils and their constituents can help us to resolve some nutritional problems such as potassium fixation and release and its fertilization management in soil. This investigation was carried out to determine the contribution of soil and their constituents (clay and silt) Kex and Knex to available potassium for plants in 12 loess-like and loess-derived soil series of Golestan province in a pot experiment of corn. Total K uptake of corn in the greenhouse experiment was used as an index of soil-available K. Results showed that the contribution of Kex to plant K uptake was more than that of Knex in clay fraction of all soils. Whereas the contribution of Knex to plant K uptake was more than that of Kex in silt fraction of all soils excluding Oghchi soil series with the highest initial Kex. Therefore, the silt fraction is an important K source for supplying the plant need for K in loess-like and loess-derived soils.

Nowadays, due to the high potential of advanced simulation models for groundwater, these models are comprehensively applied in the management and exploitation of groundwater resources. The aim of this study was to investigate and simulate the groundwater resources in Kouhpayeh-Segzi watershed and in particular estimate the hydrodynamic coefficients of unconfined aquifer. After preparation of input layers, efficient parameters in modeling, boundary conditions and aquifer gridding were determined. Then, based on the available data, the model was run and calibrated in a steady state for the water year 2002 and in a transient state for water years between 2002 and 2004. The simulation outputs were confidently verified for the water year 2005. The results indicated that the hydraulic conductivities and storage coefficients were ranged on sub-basin from 15.26 to 19.87 m/day and 0.0107 to 0.0186, respectively. From aquifer's hydrograph for a period from 1995 to 2012, water level dropped about 25 cm. This may be due to two irrigation networks (green area). This leads to rising water level. By ignoring these recharge areas, water level declined up to 80 cm per year. With sensitivity analysis in transient state to evaluate the efficacy of each parameter, the accuracy of the results of calibration model was confirmed. In addition, the hydraulic head values computed by MODFLOW were in good agreement with those that were collected from all piezometers.

Segzi, located in the east of Isfahan, is one of the most important centers of desertification crisis in Isfahan province. Human overtaking, land deformation and the presence of huge artificial topography in flat plain has created a very unpleasant landscape in the area. In this study, satellite images Cartosat-1 were used for mapping land degradation. By using DGPS, 9 points with appropriate distributions related to road junctions were selected. These points after Interior and exterior orientation determined as control points in Cartosat-1 pair images. To improve compliance, process of points development and production of 31 tie points was done. These points was coordinated in triangulation process and introduced as check points. Desirable RMSe, 0.3 pixel is obtained. Then DEM based on 40 points was prepared with 15×15m pixel size. The DEM, in GIS software was classified to 9 elavation classes by Natural Breaks method. The file of classified raster DEM convert to vector andcut and fill appeared as polygon that by encoding them, excavation map is produced in GIS with Kappa 0.95 and 0.97 overall accuracy. The Results of this study show that Cartosat-1 satellite images have ability for study of degraded lands and anthropogenic holes. The topographic changes caused the loss of natural vegetation and desertification in this area has developed.

The Palmer Drought Severity Index (PDSI), which uses hydrometeorological variables to solve a simple water balance equation in the soil and considers the drought or wet conditions as dynamic phenomena, is used for the assessment of drought conditions in many parts of the world. The main goal of this study was to assess the PDSI based on its original assumptions, its regionalized status, using the outputs of already calibrated and validated SWAT model in central regions of Iran. The PDSI was assessed through five 1) original Palmer Index without calibration in which the climate coefficients and the severity equation were derived for Kansas and central Iowa; 2) original Palmer Index in which the coefficients of severity equations were adjusted; 3) the Palmer Index with the calibration of equations in central areas of Iran; 4) the Palmer Index using the soil moisture and potential evapotranspiration from SWAT model; and 5) the Palmer Index using the soil moisture, potential evapotranspiration and runoff from SWAT model. The evaluation was conducted for 17 major basins covering the entire country with a monthly time step for the period 1990-2002. Then, using all five methods, the severity of the drought for 160 sub basins located in central Iran was calculated and evaluated. The results of this study indicated that method 4 provides more acceptable results. Also, the results of this research showed these methods clearly demonstrated (1992) as the wettest year and (2001) as the driest year. The approach used in this study is applicable to regional calibration of Palmer Index and the outputs of other hydrological models.

This research was conducted to prepare landslide susceptibility zonation (LSZ) map for the Dez-e-Ouliabasin using logistic regression model. For this purpose, at first, the most important factors affecting land sliding including slope, aspect, elevation, precipitation, the distance from road, the distance from fault, the distance from drainage, land use, and lithology were determined. Then, thelandslide inventory mapwas preparedby using field digital checks, GPS and satellite images. In the next step, the landslide susceptibility zonation mapwas preparedby usinglogistic regression method. According to the obtained coefficients for LSZ maps, the most important factor in the study area was elevation layer. The Receiver Operating Curve (ROC) index value was calculated (0.92), which indicates a very high level and suggests thatthe observed mass movements have a strong relationship with the logistic regression model.

Lack of knowledge on soil geotechnical properties can cause many problems in the construction and maintenance of irrigation and drainage networks. In general, all of unconventional soils such as gypsiferous soils can cause some problems to irrigation canals. Some studies have been conducted on a variety of problematic soils, but still there is a need for more research activities and field studies. This research was conducted to study the impact of adding perlite and pumice (5%, 10% and 15%) and micro silica (1%, 5% and 10%) on some mechanical properties of soil including shear stress, bearing capacity and Atterberg limits. Statistical analysis was done to compare their averages (P<0.01). Results showed that micro silica had the most effect on shear, bearing and condensation parameters and Atterberg limits of gypsiferous soil, and it improved these parameters of soil. Pumice improved shear, bearing and condensation properties of gypsiferous soil. Perlite reduced the shear, bearing and condensation properties of gypsiferous soil.

Desertification is currently a big problem in many countries, especially in developing countries, and includes natural processes and improper human activities. The present study was conducted to evaluate the potential of desertification with an emphasis on water, climate and soil criteria using IMDPA Model in Abbas plain, Ilam province with an area about 18028.8 hectare. Geometric averages for indices including water table fluctuations, EC of water, SAR, irrigation system, annual precipitation, aridity index, drought continuity index, soil texture, soil thickness and Ec of soil were obtained using ArcGIS 9.3 and the status map of each criterion was prepared. The results of climate indicated that 100% of the area is in severe class. The desertification intensity map based on soil criteria demonstrated that over 4843 hectare (28.86 percent of total area) and 13185 hectare (73.13 percent of total area) are in low and moderate classes, respectively. Also, the obtained results from geometric average of water criteria indices showed that 10861.4 hectare (60.2 percent of total area) and 7166.6 hectare (39.75 percent of total area) are in low and moderate classes, respectively. The results also indicated that climate with the value of 2.81 is the most influential criterion in the severity of desertification in the study area. Accordingly, it can be said that the quantitative value of desertification intensity of total area is in moderate class.

The aim of this paper is to adapt a water quality index for individual samples and to compare the results with that of the original GIS-based approach. Thirteen water quality parameters observed in 97 wells from the Shahrekord aquifer were used. In GIS-based method, quality parameters maps are difference-normalized, ranked and GWQI map is drawn. In derived method, observations from individual wells were separately and similarly treated to obtain WQI for each well. Both GWQI maps displayed similar trends and were highly correlated (R=0.91). While the minimum and mean GWQI for both methods were identical (respectively 81 and 84) the derived method estimated the maximum GWQI slightly lower (7%) and showed up to 6% difference in water quality class coverage. Overall, the derived method GWQI is more correlated with observations and performs better than the GIS-based method, and therefore, can be used for determining the overall quality of individual water samples and without the requirement of samples being spatially distributed.