Journal of Water and Soil Conservation
Year:2013 | Volume:20 | Issue:6|Papers Count:15

The origin and micromorphology of three selected pedons in mountainous Aq- Emam area (in northeast Golestan province) were investigated. The objectives were to examine 1) physico-chemical and micromorphological characteristics of studied pedons developed in different geomorphic positions and 2) evaluate the relationship between them with underlying limestone and loessial sediment as preassumed parent materials. Our results showed that the shallow soils developed on steep upslope have a cambic horizon as a main subsurface diagnostic horizon. In contrast, more thick and clayey soils developed on sloping areal have an argillic horizon with decalcified solum indicating more eluviation due to more landscape stability. Cyclical erosion and deposition which occur on colluvial foot slope must be responsible for superimposed pedo-sedimentary complexes in this position. Mass-balance calculations and geochemical ratios show that the soils in sloping midslope have a loessial nature due to windblown source and geomorphic processes. Erosion keeps these additions to some extent from appearing on the steep upslope thus these soils have a polygenetic nature derived from loesses and limestone’s insoluble residues. In brief, we can conclude that residual origin of soils formed on limestone rocks is controversy especially for those with deep solum and we should consider other possibility of material addition to soil such as eolian contamination and geomorphic processes.

The common methods in the flood frequency analysis are used to examine the flood peak variable while each flood event consists of three naturally random variables: flood’s peak, volume and duration. Furthermore, it was essential to assume the variable of interest follows a specific parametric distribution chosen from an appropriate distributions’ family. With the aim to overcome these limitations a wide range of the well-known parametric distributions functions and non-parametric methods based on kernel density estimation and orthonormal series approximation is considered to estimate the distribution of flood variables. The investigated variables is extracted from annual maximum flood series at Ahvaz hydrometric station. In order to compare between the fitted parametric and non-parametric distributions to the data, we used the statistical criterions such as Akaike Information Criteria, Bayesian Information Criteria and the Root mean square error. We then used the chi-square goodness of fit test to examine that the acceptability of the chosen distribution in the previous stage. The results showed that the flood peak follows the parametric log Pearson type III distribution function while the non-parametric orthogonal series approximation were the best fit for the flood volume and flood duration. The estimated distributions based on the orthogonal series expansion were able to capture the graphical features of the data and the corresponding fitted densities reproduced the same unimodality or multi-modality that the original histogram of data illustrates. This is not the case when one uses the traditional methods to analyze the frequency of flood.

Side weir is one of the important structures in irrigation and drainage networks. The main problem to study the hydraulic of flow in this structure is determination of water level profile along the weir and diverted flow discharge. In the present study, discharge coefficient of free flow of side weir located in various parts of the 180 degree channel bend is investigated experimentally. Also with considering the variation of water level along the weir and numerical solution of dynamic equation of spatially varied flow over side weir, the elementary discharge coefficient is related to Froude number, side weir location and the ratio of weir height to head of water. In order to compute the exponents and coefficients of relation, the genetic algorithm was used. The results showed that by using the elementary discharge coefficient, the water level along the weir and diverted flow discharge can be estimated precisely.

Rainfall simulator is one of the most effective instruments for using in soil erosion studies. Thus, many researches have been conducted in order to design, manufacture and calibrate various rainfall simulators commensurate with aim of study and climatic conditions all around the world. However, using the imported nozzles in Iran is not feasible due to high cost, and different climatic conditions. Therefore, the current study has tried to evaluate some various nozzles’ characteristics made by the authors in order to simulating natural rainfall happened in Mazandaran Province climate. For this purpose, a minute evaluation was made for a number of rainfall characteristics produced by nozzles used in other rainfall simulators as well as those made by the authors. The results of the study revealed that the nozzle designed and manufactured by the authors and coded as Apd4 could successfully simulate the natural rain under consideration. The medium drop size, velocity and fall angle of the simulated rain were respectively recorded by high speed imaging of 1.4 mm, 6.4 m s-1 and 89o.

Human being nowadays is facing water shortages problems due to various reasons including population growth, drought and reduced rainfall, development of industry and its adverse effects on water resources. The uncontrolled harvesting of groundwater resources has caused a severe drop in water table. On the other hand, loss of runoff from rainfall worldwide and especially in our country is very high and significant. Therefore the optimum use of runoff and uncontrolled surface water resources have to be applied instead of uncontrolled harvesting of groundwater resources. The aim of this study is to determine potential sites rainwater harvesting using Fuzzy Analytical Hierarchy Process. In this study, using max lambda method, fuzzy weighted of criteria were calculated. Then fuzzy layers of criteria with effect of respective weights were combined and finally combined layer was obtained. This layer was classified in five classes of, poor, average, rather good, good and very good. Results showed that the classes were named respectively, 0.635, 8.37, 34.32, 53.7 and 2.97 percent of total plain allocated to him. The final map of Birjand plain from west to the east the plain potential in harvesting rain water increases.

Hydraulic grade-control structures (e.g. drops, bed sills, check dams, etc.) have been widely used in rivers with low stability and high erosion especially in mountain streams. For proper and safe design, prediction of maximum scour depth downstream of grade-control structures in rivers has vital importance. For this reason, researchers have focused on developing simple and accurate empirical equations in form of non-linear regression models for predicting scour depth.However, accuracy of regression models is limited in general and they have good applicability just for their experimental data. In this paper, Support Vector Machines (SVM), in forecasting the scour depth downstream bed sills is applied.226 experimental data sets from literatures with different hydraulic and sediment conditions and at clear-water scouring have been used. Comparison of results in testing phase showed that outcome from the support vector machines with coefficient of determination of 0.96, root mean square errors of 0.539 and mean absolute errors of 0.4 suggest a better performance to existing regression compared equations. Also, it is found that from 5 effective input dimensionless parameters including a/Hs, D50/Hs,, S0. a/DD50 and L/Hs, only the first three parameters had greater effects on modeling maximum scour depth at bed sills and the remaining may be omitted.

Base flow is a part of flow that comes from aquifer. This section of flow is important in water resource management and hydrologic researches for e.g. in precipitation-runoff modeling and water quality evaluation. Also base flow is used calibration and validation of these models. By dividing base flow on total flow, the Base Flow Index (BFI) is derived, that shows the amount of ground water portion in total flow. The aim of this research was to choos the best method of hydrograph separation and estimating base flow.21 years daily recharge data of Tamar station in upstream of Bustan dam in Gorganrood river catchment was separated by Local minimum, fixed interval, Sliding interval and Recursive Digital Filter (RDF) or BFLOW algorithm by filter coefficients same as 0.9, 0.925, 0.95, 0.975, 0.99. Results were compared with recession curve by MAE, RMSE and Nash & Sutcliffe coefficient (E). This comparison showed that RDF by filter coefficient of 0.9 was the most suitable method for hydrograph separation in this region and 89% of total flow was base flow.

Determination of the appropriate velocity distribution and accurate estimation of river discharge is important to water resource management, water supply and safe design of hydraulic structure. Common methods in measurement of flow rate are on the basis of direct measurement of flow velocity. These methods are time consuming; costly and impracticable during flood in wide rivers. Therefore, use of methods that, while having sufficient accuracy, and the time required is also cost effective is necessary. In this research, using the principle of maximum entropy and Chiu’s velocity distribution, velocity distribution and flow in several cross sections of the Pasikhan river in Guilan province were estimated and the results were compared with measured data collected during 1389-1390. It’s found that there is a good agreement between predicted velocities and discharges based on Chiu’s method and the measured values with R2=0.996 and RMSE=3.9. So, it can be used as a quick and easy way to be replaced with conventional methods for estimating flow velocity distribution in rivers, especially in times of floods.

Soil salinity and alkalinity are considered as the most important problems in arid and semi arid areas. This study has been done to investigate the spatial variability of salinity and sodium adsorption ratio which have reciprocal effects on pistachio growth in the Kosarrize region in Rafsanjan. For this purpose a regular network of 500 meter intervals was considered and 192 soil samples were from 0-30 and collected 30-60 cm depths. Electrical conductivity of saturated soil extract (EC) and sodium adsorption ratio (SAR) were measured using standard methods. Statistical results showed that based on Pearson test, high positive correlation exists between EC and SAR at 99% confidence level. Therefore most of the salts must be of na type. Kriging maps illustrate that the variability of both parameters are greater in the first depth than the second one which is the result of different management strategies in the area. Also maps showed that Existences of excess salinity, SAR and also immethodical groundwater withdrawl and successive droughts in recent years have been considered as the main reasons of weak yield and even the loss of a major part of pistachio orchards in the region. The results showed that soil salinity and sodium in non planting areas are severe which illustrates the impact of mismanagement of the increased EC and SAR in the pistachio regions.

The groundwater is the most reliable and permanent source of water in arid and semi-arid regions, especially in the event of droughts. Alluvial aquifer of Golestan province having a wide area, relatively large thickness of sediments and non continuous deposits, has a large volume of water. Confined aquifer hydrograph reveals excessive consumption. This misuse can cause sand problems of wells, the salty water in the northern part of the plain and subsidence. In this situation, the necessity of the optimal management of this aquifer is obvious. For this purpose, aquifer characteristics should be known. Radioisotope dating is one of the newest methods in the field of groundwater developed based on the nuclear sciences. This study aimed to determine the age of groundwater in the confined aquifer of Golestan province using tritium radioisotope. This quantity, in turn, can be used as a tool to study flow paths, the horizontal and vertical flow rate, estimation of aquifer recharge rate, tracing of groundwater contamination, characterization of seawater intrusions and so on. This study showed that some samples collected from the aquifer have a new recharge (age 5 to 10 years) and the rest are a mix of new and before 1952 recharge (age 60 years).

Bio-climate studies, from the viewpoint of human comfort is the foundation of management planning. In the present study of four climatic parameters including apparent temperature, Standard Effective Temperature, Thermo hygrometric and wind for the study of human comfort was used in 14 cities. Areas of study include Abadan, Ahvaz, Bandar Lengeh and Bandar Abbas, Bushehr, Dezful, Esfahan, Kerman, Sabzevar, Semnan, Zahedan, Kashan, Yazd and Zabol, which were classified in two summer climates of very hot and hot. Meteorological variables used included daily values of air temperature, dew point temperature, relative humidity and wind speed at a height of two meters of summer, in the period 1385-1350. Results showed that relative humidity as a factor in comparison with daily dew point temperature as a factor at night represents the human comfort level in most coastal areas and is non-coastal. Thus, the standard effective temperature index (SET) because of a combination of weathering study areas daily realities, is more compliant. Accordingly, Bio-climate spectrum study areas, was in the quarter from Bio-climate sultry summer, with a range 27.5-30, Bio-climate to cool, with a range 15.5-17.8. Overall index based SET, in June that the weather warming began, eight cities in descriptive categories were hot and very hot. In August, compared with urban warming July, the city increased to nine, and in September with completion in summer, the number of cities to the city six decreased. Also, the SET index was based on any of the cities and none of the months of summer heat stress and severe cold stress. In the cities of Bandar Abbas, Bushehr and Bandar Lengeh, sultry heat stress is due to close proximity to the Persian Gulf, seems logical.

In this study, the influence of temporal variation of rainfall on linear-nonlinear response of three mountainous catchments in south west of Iran was examined. At first, the storm events were categorized into two categories including low temporal (LT) and high temporal (HT) heterogeneous events according to their temporal variation. Then, Watershed Bounded Network Model was applied to assess the catchment response influenced by rainfall temporal heterogeneity. Three different nonlinear parameters of m=0.50, m=0.61, m=0.77 as well as m=1.0 (linear response) were used. The obtained results indicated that rainfall temporal variability plays an important role on the hydrologic response of the catchments.When temporal heterogeneity of rainfall was decreased, the response of catchment tended to be more nonlinear and the value of m=0.50 resulted in more appropriate estimation of outlet hydrograph. However, by increasing temporal heterogeneity of rainfall, less nonlinear response of catchment was obtained. The nonlinear value of m=0.61 resulted in the most appropriate simulation of outlet hydrographs for high temporal variation events. Moreover, it was found that antecedent wetness of soil has an important effect on the response of catchment so that more nonlinear response can be expected in dry condition of soil rather than wet condition. When the catchment is in wet and saturated conditions due to previous rainfall, the nonlinear value of m=0.77 and linear value (m=1.0) can be used respectively.

A subsurface drainage system, in addition to controlling the water table and leaching out dissolved salts from the root zone, may cause losses of nitrogen via drainage effluent. In this research, the effect of different subsurface drainage systems on the losses of nitrate, was investigated at the consolidated paddy fields of Sari Agricultural Sciences and Natural Resources University, during a canola growing season of 2011-2012. Drainage treatments included: three conventional subsurface drainage systems with mineral envelope including drainage system with drain depth of 0.9 m and drain spacing of 30 m (D0.9L30S), drain depth of 0.65 m and drain spacing of 30 m (D0.65L30S), and drain depth of 0.65 m and drain spacing of 15 m (D0.65L15S) and a conventional subsurface drainage system with artificial envelope with drain depth of 0.65 m and drain spacing of 15 m (D0.65L15F). The nitrate concentration of effluent of subsurface drains was measured every 15 days. During the study period, the average of nitrate concentration of drainage effluent and total nitrate loss in D0.9L30S, D0.65L30S, D0.65L15S, and D0.65L15F treatments were 4.65, 3.47, 4.5, and 2.97 mgL-1 and 7.5, 4.57, 9.12, and 15.46 kg.ha-1, respectively. Based on the results, increase in drain spacing resulted in reduction of nitrate concentration of drainage effluent. Also, by increasing in drain depth, the nitrate concentration of drainage effluent was increased. Therefore, water management through a subsurface drainage system with proper drain depth and spacing, could diminish the negative effects of nitrate losses from paddy fields on water resources.

Rainfall runoff modeling and prediction of river discharge is one of the important components in flood control and management, hydraulic structure design and drought management. The goal of this study is to simulate the daily discharge in Kasilian watershed using WetSpa. The WetSpa model is a distributed hydrological and physically based model which can predict flood in watershed scale with various time intervals. The model uses topography, land use and soil type maps and also meteorological data for prediction of flood hydrographs. In this study the rainfall, evaporation and temperature data of Sangdeh meteorological station and discharge data of Valikben hydrometry station during the years 2003 to 2009 were used.36 months from April 2003 and 30 months from March 2006 were selected for calibration and test of model, respectively. The results of WetSpa model showed that this model can simulate the river baseflow with Nash- Sutcliff criteria of 64 percent in validation period, but less accuracy with high discharges. The reason may be due to small and short travel time. The sensitivity analysis showed that groundwater flow recession and rainfall degree-day parameters have the highest and lowest effect on results. This model can simulate the water balance in Kasilian watershed as well.

Due to the presence of plant food elements like nitrogen, phosphorus, potassium and organic matter, sewage sludge has been noticed as a cheap fertilizer in agriculture, but the heavy metals restrict its application as fertilizer. Zeolite is one of the natural compounds used for inactivation of these elements in soil. The aim of present research is to clarify the rate of cadmium and lead absorption of artichoke grown in sewage sludge of city infiltration system at the presence and absence of zeolite. A complete randomized factorial design as pot experiment with three levels of sewage sludge (15, 20 and 25% w/w of soil) and four levels of zeolite (0, 5, 10, 15% w/w). Results showed that among different levels of sewage sludge, the absorption of lead in were conducted parts and cadmium in root was significantly different. Also zeolite significantly (at 5%) reduced the lead and cadmium of root. The lowest amounts of cadmium and Lead of root were observed in plants treated with 10% zeolite. no having significant differences of heavy metals accumulation in aerial parts of plants under different treatments means, artichoke has patential to manage the heavy metal absorption and translocation.