Journal of Water and Soil Conservation
Year:2017 | Volume:24 | Issue:1|Papers Count:21

Background and Objectives: Since the problem of predicting and runoff estimating play a key role in integrated water resources management, therefore hydrological modeling especially continuous rainfall-runoff modeling may be most important part of water resource planning which is released from reservoir dams. Thus continuous daily hydrological models are useful tools for estimating runoff from rainfall. These models are able to estimate the runoff in ungagged basin. The purpose of this paper is to provide a continuous simulation model for Hydrologic forecasting so that investigate dominancy or dormancy of the processes.Materials and Methods: In this study rainfall-runoff processes involved in modified SCS-CN model calibrated in Leaf River Watershed located in US and Qarasou subbasin located in west of Iran through PSO optimization algorithm developed in MATLAB programming language with 9000 simulation numbers. Nash-Sutcliffe Efficiency (NSE) is used as objective function and the decision variables (14 parameters) within the specified range are randomly initialized. Optimum parameters were extracted through PSO. This model is calibrated and validated with two periods 1957-1961 and 1953 for Leaf River Watershed and two periods 1381-1384 and 1387 for Qarasou subbasin respectively.Results: Model parameters were calibrated and Validation for two case studies. Comparison of the observed and simulated runoff carried out based on three performance criteria: Nash-Sutcliffe (NSE) and Kling-Gupta Efficiency (KGE) and Root Mean Square Error (RMSE). Proposed model performed these three statistics respectively for leaf River Watershed 0.81, 0.87, 1.40 as calibration period and 0.83, 0.86, 2.53 as validation period. Reasonable values for these criteria is also attained in Qarasou subbasin but due to more reliable data, better results is expected in Leaf River watershed.A result comparison of the SCS-CN model with Hymod as a simple conceptual model, both with the same inputs revealed latter model can simulate hydrology behavior of Leaf River Watershed and Qareso River Watershed slightly better. This may be originated due to fewer model complexities and thus less parameter uncertainty of Hydmod. In spite of this superior skill in runoff simulation of Hymod, special capabilities of modified SCS-CN model which calculate hydrological components (baseflow, percolation, through flow, surface runoff and initial abstraction) may prove usefulness and efficiency of this new model easily.Conclusion: Modified SCS-CN model as a conceptual model calculates daily runoff using rainfall and potential evapotranspiration dataset. This model may be used to assess annual hydrologic components as well as total runoff values. Based on the results, the dominancy of the infiltration, evaporation and surface runoff processes were approved in Leaf River Watershed. These three processes but in reverse order is ranked in Qarasou subbasin as main hydrological components.

Background and Objectives: Investigation of the basin floods in most cases is only based on flood peak trend analysis using conventional parametric or non-parametric (ordinary linear regression (OLR), Mann-Kendall, Sen) tests. In addition to the primary restrictions, these methods usually are provided to estimate the conditional mean or median and do not consider different quantiles while assessing the appropriate domain of conditional quantiles leads to a very good understanding of trend pattern. The objective of this study is using quantile regression (QR) to estimate the time trend (conditional quantiles) of flood variables including peak, volume and duration that result in better understanding of variables of annual maximum floods (AMF).Materials and Methods: In the first step, AMF time series of Taleh-Zang hydrometry station located in southwestern Iran was considered and the time series of AMF peak flow, volume and duration were extracted.In the next step, trend analysis of AMF variables time series performed using OLR and their efficiency were investigated using fitting precision criteria, statistical significant test and residuals analysis. Then, QR lines were estimated for AMF variables trend analysis considering (0.05-0.95 with 0.01 steps) and their fitting precision criteria and statistical significant test were determined. Considering selected quantiles0.05, 0.15, 0.25, 0.35, 0.45, 0.55, 0.65, 0.75, 0.85 and 0.95 QR lines were plotted for AMF variables.Results: The OLR results indicated positive trends for AMF variables but complementary analysis showed that this method cannot be a suitable analysis for AMF variables trend analysis in this research. The QR application resulted in wide range of line slopes in comparison with OLR method. For all three variables 15% of estimated line slopes using QR were more than their estimation by OLR. Investigation of QR lines indicated statistical significant regression lines of AMF volume were related to upper bound quantiles while for AMF peak and duration were related to quantiles mid bound plus upper bound and there were a few acceptable QR lines for lower bound for all three variables so that for AMF peak, volume and duration 59%, 31% and 73% of QR lines were statistical significant considering 0.05 significance level. The fitting precisions of QR lines of upper and mid bounds were more than lower bound.Conclusion: The quantile regression can be used without affecting the limitations of conventional methods for AMF variables trend analysis to access a wider range of applied trend analysis. Also there are certain differences between AMF variables trend slopes (especially for upper bound quantiles) in comparison with those estimated with OLR therefore the OLR method could not be a useful tool for trend assessment of extreme events. The results show trend of extreme flood variables are significantly more than those estimated by OLR and in other words the OLR led to underestimation of AMF variables increasing trend slope.Moreover, multiple variables flood trend analysis using QR revealed that considering significant trends for three flood variables, the flood potential risk are significantly more than those estimated using single variable analysis.

Background and Objectives: Chelate induced-phytoextraction is one of the methods for remediation of heavy metal contaminated soils that have been attracted a lot of attention in the past decade. So far more attentions have been placed to effects of chelating agents on heavy metal solubility in soil and their uptake by plants, while there are less information about their side effects on soil environment and organisms. Soil enzyme activities can be suitable indicators to assess soil recovery after different remediation processes. The aim of this study was to evaluate the effects of EDTA and Citric acid (CA) on soil enzyme activities as well as lead (Pb) uptake by Indian mustard and sun flower.Materials and Methods: This study was conducted in a completely randomized design with factorial arrangement and three replications in greenhouse condition. The experimental factors were chelating agent treatments and plant types. The chelating agent treatments were including Control (without chelating agent), EDTA3 and EDTA5 (3 and 5 mmol EDTA per kg dry soil), CA3 and CA5 (3 and 5 mmol CA per kg dry soil). The plant species were Indian mustard (Brassica juncea) and sun flower (Helianthus annus). Also additional treatment (without Pb and without chelating agent) was considered to evaluate the effect of Pb on plant dry weight and soil enzymes activities (NP treatment).Results: The results showed that EDTA was more effective than CA for increasing available Pb concentration. Unexpectedly, the addition of CA into soil significantly decreased available Pb concentration compared with the control treatment. The results showed that between two studied chelating agents, the EDTA was appropriate for increasing Pb uptake by shoots and CA was appropriate for increasing Pb uptake by roots. The highest Pb uptake by root (2.99 mg Pb per pot) was observed in Indian mustard using 5 mmol CA per kg dry soil. Also the highest Pb uptake by shoot (1.74 mg Pb per pot) was obtained by Indian mustard with EDTA3 treatment. The results showed that soil treated with EDTA led to hormesis effect on dehydrogenase and phosphomonoestrase activity, GMea and TEA indices. The EDTA5 treatment decreased GMea and TEA indices while, the EDTA3 treatment increased these indices compared with the control treatment. The addition of both concentration of CA into soil significantly and considerably increased the studied soil enzyme activities as well as GMea and TEA indices compared with the control treatment.Conclusion: In EDTA3 treatment the shoot Pb uptake amount was higher than control treatment and, furthermore, it improved GMea and TEA indices. The EDTA5 treatment had lower efficiency than EDTA3 in increasing of shoot Pb uptake and also it decreased GMea and TEA indices compared with the control treatment. The addition of CA into soil was probably more suitable option for Pb phytostabilization in the studied soil and also considerably increased TEA and GMea indices compared with the control and NP treatments.

Background and Objectives: Soil survey and mapping are base of soil information for environmental modeling as a way to determine soil distribution patterns, describe and display it to understood and interpreted for different users. Digital soil mapping creates link between classes or soil characteristics and environmental factors affected soil formation and development by using mathematical models which can provide more precise and accurate soil maps and reducing costs of soil survey and mapping projects. This study was done to mapping soil great groups and subgroups by using Random Forest technique in the Hirmand county lands in Sistan plain.Materials and Methods: In this study 108 soil profiles were dug on about 60.000 hectares of Hirmand county lands. Sixteen environmental variables were used as estimators for soil mapping including land properties, salinity and vegetation index. After classification of soil profiles to great groups and subgroups, soil classes map produced by using random forest (RF) method. It should be mentioned 80 percent of data was used for model training and 20 percent for independent validation.Results: Pedological studies showed soils of Sistan plain haven’t high development and most of them are Entisols and Aridisols. Most soil profiles classified as Torrifluvents on great groups level and Typic Torrifluvents as a subgroup. Also the result of RF showed the lowest out of bag error (OOB) samples in soil great groups and subgroups were 43.53 and 50.59 respectively.Independent validation results showed the best accuracy obtained for soil great groups and subgroups were 48 and 53 percent respectively. Valley depth, convergence index, channel network between and salinity in soil great groups and valley depth, elevation and catchment area in soil subgroups were the most important environmental variables to estimate soil classes.Conclusion: The results showed most soils are young in the low relief lands in arid regions and these regions have also low soil diversity. Soil digital mapping and random forest technique could be useful for soil classes prediction and soil mapping in this kind of regions.

Background and Objectives: Currently, in many parts of the world and even in Iran, the high concentration of nitrate in drinking water has shown to be a serious problem, mainly caused by the introduction of agricultural wastewater and home and industrial sewage runoffs in the water resources and especially in the groundwater. The ultimate goal of the present study is to design and investigate the bio-geo-filters in order for the elimination of nitrate from the runoffs.Materials and Methods: In this research, alternate layers of non-woven geotextile filters and granular soil have been used for reduction and removal of pollution. These layers are of paramount importance in terms of their permissibility and absorption capability. For selection of materials some points have been considered, which include the material capability for pollution elimination, their accessibility and maximal cost-effectiveness.Results: After conduction of permissibility tests, the ratio of the weight mixture of the applied materials in PRB has been considered as 25% sand, 20% zeolite, 20% iron borings and 10% poplar wood sawdust. It has been observed that for pH=7, the maximal nitrate absorption efficiency by zeolite is about 69%, sawdust 29% and iron borings 12%. As indicated by the results of nitrate absorption through the final mixture of PRB in different concentrations of nitrate under optimal pH conditions while other parameters being constant, maximal absorption is due to the concentration of 150 mg L-1 and occurs in about 83%. The more the original nitrate concentration increases, the more the absorption amount goes up. Moreover, nitrate elimination with equal amounts of absorbent and optimal pH has been performed in different times for determination of equilibrium time and the maximal elimination of 100% has been obtained in equilibrium time of 96 hours. In the administered test for removal of the pollution, after the growth of biologic mass in its environment, the filter was able to decrease the amount of nitrate up to 99% after the elapse of 9 days and consequently its final amount was decreased from 100 mg L-1 to 1 mg L-1.Conclusion: The designed permeable reactive barriers with the percentage of weight mix has the capability of adsorbing a quite large amount of nitrate in a short time. Washing of adsorbent materials and removal of the pollutants result in the increase in the especial surface of the adsorbent and thus the adsorption power increases.

Background and Objectives: Deep insight about the different effect of forest tree species on soil quality properties have made soil health monitoring perspective clear concerning sustainable management; however, restoration and reclamation of deteriorates inflicted on natural ecosystems may be managed through proper selection of tree species. In this study, in order to select suitable tree species in afforestation projects, Shalman Seed and Seedling of Forest Tree Species Research Station (Guilan province) was chosen as a study area to investigate carbon storage rates and effect of conifers and broadleaves on soil properties, Consequently, soil carbon labile pools were evaluated to present unique sensitive indicator of health and soil quality.Materials and Methods: Sampling of 10 layers with thickness of 20 cm were taken from 0-200 cm depth under selected tree species plots, includingPopulus caspica, Oak (Quercus castaneifolia), Alder (Alnus glutinosa), Bald cypress (Taxodium distichum), Loblolly pine (Pinus taeda) and Juniper (Juniperus polycarpos). Cation exchang capacity, mean weight diameter, EC, pH, bulk density, total nitrogen, soil organic carbon and its labile pools were analyzed in soil samples of 0-20, 20-40, 40-60 and 60-80 cm and just for carbon storage measurements all of 10 layers (0-200 cm) were considered. The experiments were of randomized complete block (RCB) designs. Data for the same soil interval were subjected to two-way analysis of variance (ANOVA). Person linear Correlation method was used to determine sensitive indicators of soil quality.Results: Preliminary results indicated the significant effects of tree species on soil properties during soil depth. Despite insignificant differences in EC, pH and BD, our results showed that significant alterations by tree species types were found in the 0-20 cm soil layer. However, the greatest difference on CEC and MWD values were also observed in the 0-20 cm soil thickness between Alder vs. Juniper; and Alder vs. Bald cypress, respectively. All species had also higher total nitrogen (TN) and soil organic carbon (SOC) in the top soil layer (0-20 cm) followed the order: A. glutinosa> Q. castaneifolia>P. caspica>J. polycarpos>T. distichum>P. taeda. The measured amount of total soil organic carbon as a carbon storage was the highest and the lowest under Alder (A. glutinosa) and Loblolly pine (Pinus taeda) with 206.24 and 136.94 (ton OC ha-1), respectively.Conclusion: Broadleaves, especially N fixer species such as Alder had the greatest effect on soil quality properties. Broadleaves had also great potential for carbon storage with more uniform distribution during soil depth. However, among broadleaves, Alder had great effect on soil properties and soil organic matter. Finally, according to correlation values, no single and more sensitive organic carbon pool as a soil quality indicator of forest tree species changes was selected, but the complex of soil organic carbon pools could be used as sensitive indicators of soil quality and health.

Background and Objectives: Contractions have many uses in supercritical flows, such as flow conveyance from intake channels of dams to tunnel spillways, reduction of chutes width and reduction of flow conveyance time in the flood conduits. In supercritical flows studies, the formation of the shock waves has an important role. Technically, production and development of the mentioned waves are undesirable due to water depth increase because of several times increasing of inflow water depth, its spread at a wide range in downstream of channel and water surface roughness. Any weak design of channels under supercritical condition can cause to scour channel’s bed and walls, damage to equipment in the flow direction, raising maintenance costs and reduce water conveyance efficiency. In the present research, the formation of shock waves in converged transitions of open channel with rectangular and trapezoidal sections was investigated using laboratory and physical models.Materials and Methods: In order to investigate hydraulic parameters of shock waves in the converged transitions, twelve models with different geometries were used. In the present research, the studied geometric variables were the diagonal length of transition walls (0.5, 0.75 and 1 m) and side wall angle (33.69o, 45o, 60o and 90o). In all used models, the convergence ratio was 0.5. The height and instantaneous velocity were measured in different points of formed shock waves in the mentioned models for four different Froude number in the range of 3.25 to 9.23.Results: The measured values in the converged transitions showed that the velocity distribution was not uniform in the vertical direction of shock waves. Also, the results showed that by traveling wave front toward downstream cause to reduce wave velocity and increase wave height so that for various geometries, the changes trend was different. The results showed that on average, and for side slopes angels of 33.69o, 45o and 60o, the maximum height of shock waves was reduced 64.8%, 54.3% and 39.6% respectively in the comparison of trapezoidal and rectangular sections. Also, in the converged transitions and for the mentioned side slope angles, maximum shock wave velocity was reduced 39.1%, 31.6% and 16.5% respectively in the comparison of trapezoidal and rectangular sections.Increasing of side slope angle was accompanied with energy dissipation increment of shock waves for a constant Froude number and transition wall length. Also, maximum value of energy dissipation was seen for 0.5 m of wall length. The values of energy dissipation for the mentioned length, Fr1=7.26 and side slopes angels of 33.69º, 45º, 60º and 90º were achieved 14.69%, 15.43%, 16.34% and 18.72%, respectively.Conclusion: The analysis of the velocity profiles and free surface of shock waves showed that in general the reduction of side slope angle (increasing side slopes) of the transition wall, increase of diagonal wall length of the transition and reduction of Froude number have a direct relationship with the reduction of waves velocity and height. Since channels are constructed in the form of trapezoidal, the obtained results of the present research can be very useful for designer engineers.

Background and Objectives: The phenomenon of climate change and its impact on water resources is of utmost importance that has been less investigated in our country.In this study, the meteorological variables in terms of predicted climate change and were compared with the present situation. The effect of this phenomenon on Dinavar Kermanshah discharge basin taking into account the uncertainty was evaluated.Materials and Methods: To this end, results of 6 model coupled atmosphere - ocean general circulation of the atmosphere contains MPEH5, IPCM4, INCM3, HADCM3, GFCM21 and NCCCSM under scenarios of greenhouse gas emissions SRESS includes A1B, A2 and B1 were Downscaling using the LARS-WG software. To determine the accuracy of the models and scenarios, temperature and precipitation observational data were compared with temperature and precipitation available data on Canada base models and scenarios and weighted method was used to evaluate uncertainty models and scenarios. Then, base of scenario and models uncertainty, was predicted variables in coming period (2011-2034) and (2046-2069) compared with the base period (1987-2010). After the downscaling of climate variables, IHACRES rainfall-runoff models used to simulate runoff in future periods.Results: Based on the results, it's expected that temperature will be increased respectively 1.72, 1.55 and 1.39 °C in 2011-2034 and 3.27, 2.88 and 2.26 °C in 2046-2069, for A1B, A2 and B1 scenarios compared to the baseline in Dinavar basin. As well as precipitation changes respectively has been 15.22, 17.94 and 23.27 mm for A1B, A2 and B1 scenarios in 2011-2034 and -35.4, 7.97 and 2.58 mm for A1B, A2 and B1 scenarios in 2046-2069 compared to the baseline in this basin. The results showed that the amount of average flow and runoff volume has been increased in future periods except A1B scenario (2046-2069). But, flow regime of maximum daily discharges showed that it is adjust in future period. Flow - Frequency curve analysis with different probability showed that it is required to build large reservoirs to water supply in low flow seasons in future periods.Conclusion: The results showed that the amount of average temperature and precipitation will be increased in future periods. So that the increase of temperature in the second period is more than the first period and increase of precipitation in the first period will be more than the second period. Also the amount of discharges in future period will be increased so that the increase in the first period will be more than the second period and the volume of runoff in the first period will be more than the second period and in both periods were higher than the base period. But flow regime of maximum daily discharges showed the decreasing in future period, So that the maximum discharge rate decrease in the second period is more than the first period. Flow-Frequency curve analysis also showed that in the absence of water storage, agriculture and industry and drinking in the area faced with supply problems.

Background and Objectives: Nitrate anion can be repelled by the negative charges on clay minerals' surface and leached from soil profile to surface and groundwater. Natural clays are not effective adsorbents and entrapment media for anions, low water soluble, nonpolar and non-ionic organic molecules. However, the natural clays may be modified using organic cations (surfactant) to adsorb and trap varieties of nonionic, anionic compounds and enhanced anions retention capacity that are detrimental to our aqueous environments. The objective was to study the adsorption efficiency and desorption of nitrate in aqueous solutions by modified Iranian zeolite-clinoptilolite (Semnan) with hexadecyltrimethylammonium bromide (HDTMA-Br), a cationic surfactant.Materials and Methods: The micro and nano-zeolite was separated by centrifuge method. The micro and nano-zeolites were first modified by HDTMA-Br. In this study, adsorption efficiency in initial concentrations of nitrate by modified zeolite with surfactant loading of 100 and 200% ECEC was investigated in a completely randomized factorial design. The nitrate release as affected by time at 4 and 14 mM of nitrate in surfactant loading 200% ECEC were also evaluated.The external cation exchange capacity (ECEC) of zeolite was determined by replacing the Na in non-zeolitic exchange sites with tert-butyl ammonium ions. Structure and morphology of zeolite was determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and atomic force microscope (AFM).Results: The results showed that adsorption efficiency of nitrate by nano-organozeolite with surfactant loading of 200% ECEC in 3, 6, 14, 20 and 30 mM nitrate were 92, 88, 77, 67 and 56%, whereas in micro-zeolite were 75, 67, 50, 41 and 33% respectively. Adsorption efficiency of nitrate by micro-organozeolite with surfactant loading of 100% ECEC were 53, 46, 35, 28 and 20% respectively. In nano-organozeolite, nitrate desorption were 2.6 to 5.7% and 8.9 to 12.2% in 3 and 14 mM, respectively, whereas for micro-organozeolite were 21% and 33% in 3 and 14 mM of initial nitrate concentration, respectively.Conclusion: Results of this research showed that the particular separation of zeolite, initial nitrate concentration and level of surfactant loading had a highly effect on adsorption efficiency and cleaning of nitrate in aqueous solutions. Moreover, nano-organozelite showed high adsorption efficiency of nitrate and good quality to trap and retain of nitrate.

Background and Objectives: Nowadays, land degradation is a serious problem in many parts of the world. Land degradation occurs as a result of various factors including climatic change, improper land use and management in arid, semi-arid and dry sub-humid areas. It has been recognized as a major socioeconomic, social and environmental problem in many countries of the world. Various models are provided in order to assess desertification in the world. It seems that the MEDALUS model has apparent advantages compared to the other ones, such as easy style, data accessibility and taking geometric mean. The objectives of this study were to mapping and quantitative evaluation of land degradation in Siyahpoush catchment using MEDALUS and adjusted MEDALUS model.Materials and Methods: In this study, MEDALUS and adjusted MEDALUS models were applied to desertification assessment and mapping in Siyahpoush catchment. For this purpose, four important criteria (soil quality, climate, vegetation cover, management and policy) which were effective on desertification have been selected. Indices for each criterion are defined in the MEDALUS model. Index layers for each criterion were prepared using GIS. These indices were ranked in accordance with MEDALUS model. The geometric mean was then calculated and map was produced for each criterion. Land degradation map of the study area was finally prepared using the geometric mean criteria.Results: The result showed that management quality and climate quality criteria with a geometric average of 1.91 and 1.62 have played the most important role in sensitivity of the area to desertification. Soil quality criterion with a geometric average of 1.39 and vegetation quality criterion with a geometric average of 1.41 were classified in moderate and high quality, respectively. Therefore, vegetation quality was determined as the most appropriate criterion.The ESAI index for MEDALUS and adjusted MEDALUS model ranged 1.38 to 1.79 and 1.37 to 1.93, respectively. This means that all area is located in critical class of desertification.Conclusion: The management and climate quality were identified as the most inappropriate criteria and vegetation quality was found as the most appropriate criterion. According to the obtained results, the study area is classified as critical class by ESAs model, so that 90.1% and 99.2% of the study area is located in the severe critical sub-class (C3) whit MEDALUS and adjusted MEDALUS model, respectively. However, implementing management policies would help to restrain this phenomenon at field or regional level. In addition, monitoring of land degradation needs to be considered that have involved more effective indices in this region.

Background and Objectives: The scarcity of water resources caused by environmental pollution and population growth has become an issue of vital importance around the world.Assessing the water resources for the future is of great significance for water resources management and policy maker. Despite recent progress in developing reliable climate models, the different uncertainties inherent in climate change projections. Therefore, a successful application of a climate parameters simulation in applied water research strongly depends on uncertainty analysis of model output. Here we present a detailed and quantitative uncertainty assessment of rainfall for first future epoch (2011-2040) and second future epoch (2040-2070), based on the projections of wide range of rainfall projections resulting from the factorial combination of four emission scenarios, five GCMs and two downscaling methods (LARS-WG and SDSM) in Bojnourd and Mashhad synoptic stations. This enabled us to decompose the uncertainty in the ensemble of projections using Box-whisker plot and Bootstrapping method.Materials and Methods: Bojnourd and Mashhad synoptic stations based on the reliability of their data and long date series were chosen for this study. A 30- year base weather data (1982-2011) including daily precipitation, maximum and minimum temperature, solar radiations were obtained from Iranian meteorological organization. The uncertainty in precipitation change in response to the general circulation model (GCM) from HadCM3, NCPCM, CNCM3, GFCM2, CGCM3, SRES emission scenarios (A1B, A2, B1 and B2) and two downscaling method (SDSM and LARS-WG) was investigated in two future epochs. In this study, we evaluate the impact of uncertainty in climate change projections on the future precipitation by Box-whisker plots and Bootstrap technique. In the first step, the outliers were excluded by box-and-whisker plots. In the next step the precipitation projected which is reported by ten different scenarios, is then a vector of about 6000 bootstrap replications (500 per model), from which we take the 2.5th and 97.5th percentiles to calculate the range containing 95% of projected estimates. The fundamental idea of the model-based sampling theory approach to statistical inference is that the data arise as a sample from some conceptual probability distribution.Results: The GCM models show wide variation in their results, particularly for Bojnourd precipitation forecasting. According to Box-whisker graph in Bojnourd synoptic station (BSS), the projected precipitations by CGCM3 and HadCM3 in first and second epoch fall under the 2.5th and 97.5th percentiles. In Mashhad synoptic station (MSS) some scenarios projected precipitation significantly different from other scenarios which were belonging to CGCM3 in January and March and GFCM3 in summer months. On the basis of these results, it is clear that both stations will experience an increase in precipitation for epoch1 and epoch2, with the largest increase found for epoch2. In the next step confidence interval estimation by the bootstrap method is investigated for the uncertainty quantification of precipitation projections using therandom sampling method. In BSS the confidence interval band is large in all month except in August and October. It is interesting that for MSS, the range in GCM predictions is relatively small for all seasons except in spring. This means that the uncertainty in climate predictions is considerably smaller for these months. Results also illustrate that the confidence interval band in Bojnourd station is wider than Mashhad station and suggest that precipitation projections is highly uncertain than in Mashhad Station. On the other hand in both stations climate predictions for the far future are more uncertain than climate predictions for the near future.Conclusion: All GCM and downscaling outputs are inherently uncertain because no model can ever fully describe physical systems. Most studies in the literature on the climate change projection do not capture the full range of plausible future climate variation, making their findings seem more precise than they actually are and as a result making them less credible among climate scientists and potentially misleading for policymakers. We feel that the methodological approach presented here addresses a fundamental shortcoming in the past research. We show that failing to account for climate uncertainty lead to a false sense of confidence about the likely future impacts of climate change, when in fact impacts are actually far less certain.

Background and Objectives: Nowadays, different materials such as applying Fe chelates, soil acidifying materials and industrial wastes are used to correct soil Fe deficiency. Slag and convertor sludge of steel factories are useful as a reclamation material for Fe nutrition among the industrials wastes for this purpose. These materials contain considerable amount of Fe produced in large quantities every year. Application of slag and convertor sludge to soil may affect bioavailability and chemical forms of Fe in soil. On the other hand, environmental pollution caused by heavy metals such as lead (Pb) is a serious and growing problem and can affect nutrient management such as Fe. Considering interaction of Fe and Pb, this research was performed to investigate the effect of converter sludge enriched cow manure on the changes in Fe bio-availability in a Pb polluted soil.Materials and Methods: A factorial experiment with a randomized complete block design with 3 factors in three replications was conducted in greenhouse conditions. Treatments were consisting of applying enriched cow manure (0, 15 and 30 t ha-1) with 0 and 5% pure Fe from converter sludge. In addition, the soil was polluted with Pb from Pb (NO3) 2 source at the rates of 0, 200, 300 and 400 mg Pb kg-1 soil and incubated for one month. Then, the enriched cow manure was added to the Pb polluted soil and corn (Zea mays L. single grass 704) seeds were sown. After 60 days from the experiment, soil physio-chemical properties and soil and plant Fe concentration were measured.Results: Increasing the loading rate of cow manure from 0 to 15 and 30 t ha-1 in a Pb polluted soil (300 mg Pb soil-1) caused an increasing in DTPA extractable-Fe by 21 and 35 times, respectively. Similar to this result, root and shoot Fe concentration was also increased, as, applying 30 t ha-1 cow manure in a polluted soil (200 mg Pb soil-1) caused an increasing in root and shoot Fe concentration by 7 and 12.3 times, respectively. Enriched cow manure with converter sludge had also a positive effect on root and shoot Fe concentration, as, applying 30 t ha-1 enriched cow manure in a Pb polluted soil (200 mg Pb soil-1) caused an increasing in root and shoot Fe concentration by 2 and 7.7 times, respectively.Conclusion: The greatest DTPA extractable Fe and root and shoot Fe concentration was belong to the non-polluted soil treated with 30 t ha-1 cow manure enriched with 5% Fe pure from converter sludge. Considering the interaction effect of Fe and Pb, increasing the soil Pb pollution caused the significant decreasing in soil Fe availability and root and shoot Fe concentration. The result of this study showed that applying cow manure enriched with 5% Fe pure from converter sludge can probably increase soil and plant Fe bio-availability. However, the role of applying cow manure on decreasing Pb bio-availability and thereby, increasing soil Fe bio-availability (iron and lead competitive effect) cannot be ignored.

Background and Objective: Evaporation is one of the main components of water losses in submerged irrigation method in paddy fields. The amount of evaporation is a function of temperature, relative humidity, wind speed, vegetated surface, submerges depth, water table level and other elements. In different intermittent irrigation managements, paddy fields frequently are under submerged and non-submerged situation. In each irrigation practice, the water level changes from submerged to capillary crack. This research aims measuring of evaporation rate during rice growth in different submerged depths in Guilan Province paddy fields in Rice Research Institute near meteorological research station in 2013.Material and Methods: Five different water level treatments (5, 2.5, 0, -5, -10 cm) where applied to the farm in three repetition and using mini Lysimeters the evaporation is measured in daily scale in the middle of pig plots.Results: The results show that evaporation in different submerged levels is significantly different in 5%.The most and least evaporation amounts are consequently seen in 0 cm and 10 cm treatments respectively 120.8 and 94 millimeters. In all treatments the evaporation reduces during the time to the half. Precipitation minimize also evaporation rate till 75%. Neglecting precipitation dates also does not change the difference between treatments. The comparisons show that higher levels of water on the soil surface cause higher evaporation losses. By reducing water level and narrowing water depth on soil surface, especially in vegetation period evaporation reduces. If the thickness of this layer reduces and reaches to zero or soil became semi saturated, evaporation increases again. If the thickness of this layer reduces and reaches to zero or soil became semi saturated evaporation increases again. Then when the soil became dryer and the water level stays at -10 cm below soil level, the evaporation decreases significantly.Conclusion: The results of evaporation measurements and its fluctuations are highly strongly to fluctuations of soil temperature in every treatment (in depth of 5 and 10) and water temperature and treatments which have higher records of temperature in the soil and water environment, have severer evaporation rates. In case of enough available water, presence a thin layer of water on top soil surface can reduce effectively evaporation. But in the absence of water necessary to maintain submergence, to reduce evaporation losses it is recommended to keep water level table in lower than 5 cm from top soil surface.

Background and Objectives: In order to provide feasibility of winter cropping in paddy fields, subsurface drainage systems should be installed to overcome waterlogging problems and to remove excess rainfall. In different countries, installation of subsurface drainage in paddy fields caused increases in yield and facilitated working conditions on the land. In Pakistan and India, the installation of subsurface drainage system resulted in increases in cotton, sugarcane, rice, and wheat yields. Totally, evaluation of influences of subsurface drainage systems showed positive effects on rice yields, also it can provide possibility of second crop in paddy fields.Because of new installation of subsurface drainage systems in Northern Iran paddy fields, investigation of canola yield as a second crop has a great importance. By determining amount of yield improvement and harvested yield, farmers and government will have good point of view in future work.Materials and Methods: In this study, the effect of three conventional subsurface drainage systems and a bi-level drainage system along with a control treatment on canola yield was investigated in paddy fields of Sari Agricultural Sciences and Natural Resources University.Experiments were done in randomized complete block design with 5 treatments in 2014-15.Water table depth were measured daily and in harvest time some of crop index like plant number in one square meter, pod number in plant, grain number in pod, 1000 grain weight and yield of canola were determined. Data were compared statistically by Combined ANOVA with least significant difference (LSD) test at the 0.05 probability level in SAS statistical software.Results: The results of statistical analysis showed that plant number, pod number, 1000 grain weight in subsurface drainage treatments were significantly more than control treatment. Also, the canola yield in subsurface drainage treatments were significantly 425 to 1025 kg ha-1 more than that in control treatment. However the rainfall during germination time was much, the drains worked well and water table was lower than 30 cm.Conclusion: Improvement of aeration and quicker discharge of excess water in subsurface drainage treatments during canola growing season caused more canola yield. Generally, grain yield in drainage treatment with 0.9 m depth and 30 m spacing, Bi-level drainage treatment, drainage treatment with 0.65 m depth and 30 m spacing and drainage treatment with 0.65 m depth and 15 m spacing were 55, 35, 29 and 22% more than that in control treatment. Due to these results and large areas of paddy fields in North of Iran, use of these areas during wet seasons for canola cultivation can be a helpful solution for producing oil grains and achieving to self-sufficiency.

Background and Objectives: Applying hydrologic models and forecast is a necessity in different studies in water resources. There should be multiple assumptions in forecasting the outflow of watersheds due to different complex relations in hydrologic cycle. Because of assumptions and simplifications those applied in the structure of models and developed relations, forecasts made by rainfall runoff models are always subject to uncertainties. Different sources of uncertainty are categorized into three parts: first, the uncertainty attributed to the applied data, second, the structure of model and third and the parameters. It is also necessary to address uncertainties and improve the precision of the forecasts. Therefore, there are multiple methods developed to analyze uncertainties. For this aim, data assimilation is a recommended approach and particle filter method is one of the developed models in this regard. The main goal of this research is to apply particle filter to update and improve the HYMOD rainfall runoff model forecasts based on observed stream flow. In addition, by the use of this approach, quantification and decreasing the uncertainty is evaluated based on different sources of error.Materials and Methods: In this study, improving the forecasts is implemented by data assimilation approach. To this aim, particle filter method, successive Bayesian estimation and posterior probability density function are applied for obtaining the soil moisture and Hymod parameters in daily scale in Kassilian river basin with approximately 67 square kilometers area.Particle filter is based on Bayes equation and maximum likelihood function of errors for the given time period. Moreover, this method should be combined with statistical resampling that prevents divergence of the analysis and corrects degeneracy, sample impoverishment of particles and tendency of the state variables particle weights to unit value (1).Results: Applying particle filter method makes it possible to use the intended model parameters for simulating and forecasting by random ensemble parameters generation and calculating prior probability density function. This method is also effective for precising forecasts and simultaneous application of parameters and soil moisture variable in analysis. Also this method helps to modify the forecasts using Baysian theory and definition of primary errors maximum likelihood function. In addition, this method also represents the posterior probability density function and corrects the prior density function.Conclusion: The results show applicability of particle filter method in combination with statistical resampling for hydrological data assimilation and improvement of the precision of forecasts of outflow from Kassilian river basin. It is shown that, the applied method improved the Nash-Sutcliffe statistic in comparison with open loop procedure. As the Nash-Sutcliffe statistic improved by 22%, rising from 0.55 to 0.67.

Background and objectives: Sharp crested weirs are used for the purpose of flow measurement, flow diversion and water level control in hydraulics, irrigation and environmental projects. So exploring the features and characteristics of the hydraulic properties are an important issue in the design of these structures. Various studies have been done about sharp-crested weir. Few studies have been done about the impact of inequalityin the upstream and downstream bed level on hydraulic properties. The sharp-crested weirs like other weirs, unequal in the upstream and downstream bed level (such as the Check drop) cause changes on the hydraulic characteristics that must be studied.Materials and Methods: Research conducted on Hydraulic laboratory which Situated in Research Institute of Soil Conservation and Watershed Management. The experiments were performed in the flume with 14 meters length, width of 60 cm and a height of 50 cm. Sharp crested weirs was built of Plexiglas with a thickness of 6 mm, edge thickness of 2 mm, a height of 20 cm and a length of 60 cm in the workshop and was placed within the flume. Upstream bed level increased with proper materials in three level 5, 10 and 15 cm from floor. At any stage, values of the weir crest level and upstream and downstream water level were recorded for different discharges. Computational Fluid Dynamics (CFD) was used to generalize the results. For this purpose, FLOW 3D software was used for modeling of Free-surface flow over weir. In This software, weir and it’s free surface are considered by using Fractional Area Volume Obstacle Representation and Volume Of Fluid methods respectively. The governing equations were Navier-Stokes and continuity equations for incompressible flows. For modeling turbulence, was used Re-Normalization Group (RNG) model.Results: The results showed a good agreement Between experimental data and numerical simulation.changing procedure of discharge coefficient was the same in both methods. Maximum deference in the H, extracted from two methods, is 5% that is acceptable. The results showed that by increasing the upstream bed level, the upstream flow depth decreases, velocity and Froude number increase. But rising the upstream bed level to 0.75 (Z/P=0.75) does not affect on the discharge coefficient. In numerical method, Discharge coefficient values forH/P ≥ 0.5 can be considered the average value of 0.73 for all cases.With increasing discharge Froude numbers are converging in different ratios of upstream bed level. In the special case where the upstream bed level is rised to Crest (vertical drop or Z/P=1), the discharge coefficient value will be 0.6. This value is the lowest between all cases and its magnitude is equal to discharge coefficient of the broad-crested weir. So in this case, the level of water is higher than the same rate of discharge in the other cases and this difference goes up by increasing discharge. In Z/P=1 he Froude number will be equal to a fixed value Fr=0.94Cd.Conclusion: In summary it can be concluded that by increasing the upstream bed level, the Froude number will increase and thus the nape becomes more horizontal. In the range of H / P≥0.5, except when the Z/P tend towards one, in other cases, the rising bed level and the increasing H/P have no significant impact on discharge coefficient. In the Z/P<0.75 changes of upstream bed level do not affect on the discharge coefficient. In Z/P=1 both discharge coefficient and the Froude number are constant and their magnitude are respectively 0.6 and 0.56.

Background and Objectives: The use of storage dams plays a key role in the development of industry, agriculture and employment communities Bottom outlet tunnels are one of the most significant components of the reservoir dams which are used in flood evacuation and control.They consist of inlet duct, main conveyance tunnel and flow regulator structures including gates and valves. A major problem with bottom outlet gate of dams is cavitation which happens in the high flow discharge. This phenomenon would destroy the surface of structure. It has been demonstrated that flow aeration is an effective way to reduce the cavitation damages. In this regard, the flow aeration rate is an important discussion that must be noted. Since, in this paper aeration coefficient evaluation is assessed.Materials and Methods: This study, is to estimate the aeration coefficient of bottom outlet gate of four dams (Alborz, Zhaveh, Gotvand Olia, Jareh) using Gene Expression Programming (GEP) approach. To achieve this aim, experimental data were used collecting from hydraulic structures laboratory of Tehran Water Research Institute to train and test the model. The aeration coefficient was influenced by compressed Froude number (Frc) and aerator area to gate area ratio (Aa/Ag).30 chromosomes and 3 genes were chosen to GEP performance. The model ability was assessed by two statistical parameters of correlation coefficient (R2) and root of mean square error (RMSE).Results: The results show that GEP predicted the aeration coefficient of bottom outlet gates of dams with R2 of 0.803 and 0.639 and RMSE of 0.096 and 0.125 for training and testing stages, respectively. This model gave better results compared by regression equation with R2 of 0.718 and 0.402 and RMSE of 0.114 and 0.171 for training and testing parts, respectively.In the other words, the error of aeration coefficient prediction was decreased about 28% using GEP approach.Conclusion: The results show that GEP intelligence approach is an adequate model to predict aeration coefficient of bottom outlet gates of dams. Also, the results of traditional regression equations were improved using this method. In the other words, these results indicated that GEP is reliable to evaluate the aeration coefficient of bottom outlet gates of dams by more accurate estimation to prevent cavitation phenomenon. So, use of this way is suggested in future studies related to this topic.

Background and Objectives: Low flows are the most important parameters for the qualitative and quantitative hydrological analysis of the catchments and have a significant role in the planning and water resource management. Several factors are involved in low flow trend, including, land use and vegetation that directly and indirectly affected by the interference of humans. Low flow data, within a watershed is used for a wide range of activities including: drought planning, investigation of ecosystem status, planning water demand, water pollution issues, development projects in the field of power generation and environmental studies. Low flows from various aspects have been investigated. Some of these cases can be pointed to research Riggs (1990), Warner (2003) and McMahon and Nathan (1991). They were used a linear correlation and multivariate regression methods to estimate low flows. For prediction and investigation of the effect of land cover variation on flow parameters, several studies have been done, including research of Zhao (2010) and Wei and Zhang (2010). The impact of land use and climate change on the hydrology of Alabama coastal basins by Ruoyu et al. was evaluated by hydrological modeling.Direct and indirect effects of human in land use changing and its role on water resources have studied by some researcher. Including: Kashaigili (2008) and Delgado et al. (2010) the aim of this study was to investigate the role of land use change on a number of low flow indices in Taleghan catchment.Materials and Methods: In this research, by using topographical maps with the scale of 1: 250000 and 1: 50000 and Positioning the Galinak gauging stations in Taleghan river, the study area was Determined.Then using aerial photographs with the scale of 1: 20000 and TM and ETM satellite images of 1366 and 1381, land use map in the four-level of rangeland, dry land farming, irrigated and rock outcrop were prepared. Then land use change was calculated. Base flow index using daily data and based on, one parameter recursive digital filter algorithm were extracted by HydroOffice, 2012. Low flow indices with 3, 7, 15, 30 and 60 days duration using daily data were extracted. Then relationship between low flow indices and land use in the period of study were investigated. In this research, land use changes in the basin using the interpretation of aerial photographs and satellite imagery in three intervals of the years 1349, 1366 and 1381 were investigated. Base flow index using daily data and one parameter recursive digital filter algorithm were extracted. Low flow indices with 3, 7, 15, 30 and 60 days duration using daily data were extracted. Then relationship between low flow indices and land use in the period of study were investigated.Results: The results showed that all of the low flow indices in the first period of study have experienced a steep upward trend. This trend in the second period during the years 1349 to 1366 also shows an increasing trend but with little slope. In the period 1366- 1381 all indices, including base flow index and other low flow indices a minimal decline have experienced. Increasing rangeland coverage of 81 with respect to 49 was in accordance with the increasing of indices in the period studied.Conclusion: Land use Changes due to direct and indirect human intervention has a direct impact on the trend of low flow indices. Conformity of vegetation cover trend in 49 to 81 years with trend of low flow indices, indicating a positive role of rangeland on increasing the low flow indices. So rangeland protection to ensure, base flow continuity in the research area, is essential.

Background and Objectives: Proper designing and using of spur dike structure can control scour and it can improve the stability of bridge. The effects of different types of spur dikes on the flow properties and sediment transport are different and they depend on the scour designing parameters, layout of spur dike, flow hydraulic, kind and size of sediment. Different factors have affected on the scour phenomena. For study of these factors different researches are necessary. The aim of this research is the study of effective parameters of asymmetric T-shaped spur dike on the maximum scour depth in bridges abutment in a compound sections.Materials and Methods: This research has conducted on a rectangular shaped flume with dimensions of 1 m width, 12 m length and 60 cm depth in hydraulic laboratory of Agriculture collage, Shahrood University of Technology. Asymmetric T-shaped spur dike with 4 relative of upstream wing wall length to downstream wing wall length (0.2, 0.5, 2 and 5) installed at distances of 9, 18, 27, 36 and 45 cm from the abutment. The amount of scour in the front of abutment with discharges 18, 20, 22, 24 and 26 lit/s was studied.Results: Result of this study reveal that the maximum scour depth is decreased with increasing of the ratio of the upstream wing-wall length of spur dike to the downstream wing-wall length and also results show that the scour depth is decreased when the distance of spur dike from the abutment is increased. Decreasing of the scour depth was 100% and 70% for discharge of 18 lit/s and 26 lit/s, respectively. With dimensional analysis of the hydraulic parameters such as discharge, average flow velocity, depth of water and geometric parameters of spur dike such as length of spur dike, length of wing-wall and distance of spur dike from the abutment, a dimensionless equation was achieved and finally based on the experimental data a new equation presented to estimate the maximum depth of scour around the abutment.Conclusion: The main results of this research revealed that with increasing of the distance of spur dike from the abutment, the effect of spur dike on the scour around of abutment increased and as results the scour depth in the front of abutment will decrease.

Background and Objectives: Rill erosion is a major factor of soil loss in the marl formations.The marl formations are very susceptible to water erosion processes and cover a wide area in some watersheds in arid and semi-arid regions. Knowledge of temporal variation of rill erosion and effect of during a rainfall event can provide information on the mechanism of rill erosion in the hillslopes. The rate of temporal variation of flow characteristics and rill erosion can be affected by the rainfall intensity. Therefore, this study was conducted to the study of temporal variation of flow characteristics and rill erosion in a marl soil under different simulated rainfalls.Materials and Methods: A laboratory experiment was carried out using six simulated rainfall intensities ranging from 10 mm h-1 to 60 mm h-1 with three replications. Soil samples were collected from the marl formations in west of Zanjan and separately purred to a flume with 4 m in length and 0.94 m in width putted on 10% slope. Rill erosion and flow characteristics (discharge and concentration) were measured at 5-min from starting flow/ runoff in each rainfall intensity. Rate of rill erosion and flow characteristics versus rainfall duration was obtained and differences among the different rainfall intensities were computed using the variance analysis method.Results: Results indicated that there are substantial differences in the flow starting time, flow concentration and rill erosion among the rainfall intensities (P<0.001). Rill flow and erosion rapidly occurred with increasing rainfall intensity. Rill erosion increased speedily during rainfall and reached to approximately constant value in the last times (about 45 min). The flow concentration appeared also a similar trend with the rill erosion, while flow discharge showed an increasing trend in the last times. Most of erodible particles were eroded during 45 min from rainfall and after this time, large flows containing lower concentration/sediment were observed in the rills.Conclusion: The study revealed that the threshold and pick time of rill erosion were strongly varied during rainfall. The variation trend of rill erosion during rainfall increases with increasing the rainfall intensity. Rill erosion temporally varies during rainfall. Rill erosion is strongly dependent on the flow discharge in initial times of rainfall, while in the last times its trend is very different from flow discharge.

Background and Objectives: Precision in designing and correct managements on sprinkler irrigation systems can help to improve and develop of these systems and cause efficiency raising in agriculture.Materials and Methods: In this research, constant classic sprinkle irrigation systems (four systems) and one wheel move sprinkle system were evaluated and compared (in 2015). To evaluate of irrigation systems, Christiansen’s uniformity coefficient (CU), distribution uniformity (DU), application efficiency of low-quarter (AELQ) and potential application efficiency of low quarter (PELQ) were calculated in the experimental plots and adjusted with pressure changes for the whole system.Results: The maximum an uniformity coefficient and distribution uniformity in all the systems were in Darab, Arsenjan and Sarvestan counties and they were 80.78, 69.56 and 68.21 percent for uniformity coefficient, respectively. These values showed normal distribution of data and symmetry measurements than the average and the distribution uniformities were 66.12, 55.4 and 53 percent, respectively.Conclusion: The reason of low distribution uniformity in systems was water losses for deep percolation, outdated system, pressure loss and pressure and discharge variations of sprinklers.Homogenization of application efficiency potential of low quarter and the actual application efficiency in all evaluated irrigation systems were showed supply water less than plants water requirement. These values were low that showed water losses because of deep percolation and outdated systems.