Journal of Water and Soil Conservation
Year:2011 | Volume:18 | Issue:2|Papers Count:16

Identification of the existence or non-existence of trends in streamflow and floods by the statistical analysis for water resources management and infrastructure designing is an inevitable issue. Thus, in this study, three hydrologic variables of mean daily discharge, maximum daily discharge and peak discharge were analyzed for detection of any probable trend. Using three non-parametric tests including Mann-Kendall, Spearman’s Rho and Thiel-Sen estimators, the trend of hydrologic variables in the Atrak River basin in northeast of Iran was studied for 10 discharge gauging stations during the 1972-2003 period. The results indicated that the three tests proved the same conclusion about trend existence. Except one station, all other stations within the study area show increasing trend for the peak discharge but for the mean daily discharge show opposite trends. For 70 percents of stations, the observed downward trends in the mean daily discharge are significant at 0.05 or lower levels whereas 30 percents of stations exhibit significant upward trend in the annual peak discharge at 0.05 or lower significance levels. None of the stations present a significant downward or upward trend for the maximum daily discharge. Based on the results it can be concluded that the hydrological regime of the Atrak River basin has undergone considerable changes which is indicated by decrease in annual discharge and increase in magnitude of floods. Therefore, water resources management and planning authorities should consider these changes in the assessment, designing and planning processes. The changes in hydrologic regime of the Atrak River basin is either related to climate or land use changes.

Ammonium Acetate extracted soil potassium is the most common plant available potassium evaluation method in soils, but it has been shown that this method was not been suitable to fertilization recommendation of potassium in calcareous soils. This study was conducted to determine correlation between soil mineralogical combinations, potassium Q/I parameters with potassium extracted by normal extraction method determination. Therefore, 18 different soil samples collected from farms of different provinces. Beside difference in physical, chemical and mineralogical characteristics, soils were in different available potassium categories (low, medium, high). Dominant clay minerals of soil samples were identified by X-Ray, then the Q/I parameters were calculated. The results showed no significant correlation between the types of dominant minerals with available potassium. But, some of the Q/I parameters, potassium absorbed by specific sites (KX), labile potassium (KL), and free energy of potassium replacement (ΔG°) were highly correlated with potassium ammonium extractable. Difference in physical, chemical and mineralogical properties could explain different Q/I parameters in soils. Results showed that different soil characteristics could directly affect Q/I parameters, so that it can give a better estimation of soil potassium availability than ammonium acetate extraction.

A climatic gradient was selected in order to evaluate the effects of the climatic factors on soil genesis, evolution, physical and chemical properties of loess derived soils in eastern Golestan Province. This gradient includes udic, xeric and aridic moisture regimes and mesic and thermic temperature regimes. Seven soil profiles were located under pasture land use were studied. Results showed that Mollisols with argillic and calcic subsurface horizons were present in the region with udic moisture regime and mesic temperature regime, while in the regions with xeric moisture and thermic temperature regimes, Mollisols have only cambic horizon and Inceptisols have ochric epidedons and calcic and cambic subsurface horizons. Meanwhile Aridisols and Entisols were eventually formed in aridic moisture regime and thermic temperature regime and Entisols did not show any evolution. Micromorphological studies showed that with reduction of rainfall and increase in temperature, soil microstructure changed from angular blocky and sub-angular blocky with strong separation to massive and blocky microstructure with weakly separation. Moreover speckled b-fabric changed to crystallitic b-fabric followed by the decrease in rainfall. Soil physico-chemical properties showed significant differences in soil texture, amount and depth of lime leaching, the amount of organic matter, pH, electrical conductivity of saturated extract, and cation exchange capacity. In areas with higher rainfall, the clay content as the weathering product of the silt particles has increased.

Soil moisture in different potentials is one of the most important input parameters in majority of models, which related to agriculture, water and soil sciences. Pedotransfer functions (PTFs) predict the less readily properties using easily collected soil parameters; so they have these advantages to be inexpensive and easy deriving. Two important targets were designed in this paper. First target is performance evaluation of Fuzzy Neural Networks (Fuzzy-NN) and Genetic Algorithm Neural Network (GA-NN) in comparison routine neural networks such as Multilayer Perceptrons (MLPs) in predicting moisture in predefined potential points. The second target is introducing and evaluating a new PTF, pseudo parametric and comparing its performance in modeling water retention curve with point and parametric PTFs. For achieving these targets, 122 soil samples from north and northeast of Iran in variety of soil textures, such as loam, clay, clay loam and sandy loam were selected and modeling results from different networks were compared. Results showed that in general the performance of all structures of neural networks was acceptable, so that the average of R2 and RMSE statistics were 0.0316 and 0.842 respectively. The best and worse results belonged to pseudo parametric (with R2=0.92 and RMSE=0.022) and Parametric PTFs (with R2=0.72 and RMSE=0.044), respectively. In addition, according to results we can say using Fuzzy-NN could not improve the performance of MLPs but GA-NN could.

Sediment transport and settling leads to some outcomes such as sedimentary island establishment in river stream and consequently, decrease in transfer capacity of flood water flows, decrease in useful life of dams and depots saving capacity, corrosion in river factor foundations, damaging the water buildings and farms, settling in the canal bed and many other problems. Also it is necessary correct estimation of the rivers sediment load in all hydraulics projects is necessary. One of the methods of sediment estimating is hydrological methods. Hydrological methods are divided to several categories, such as USBR, FAO, Median of groups, MVUE, QMLE, and Smearing. In this research estimating of sediment in Arazkoose hydrometric station which is located on Gorganrood watershed was carried out by these methods. Therefore, sediment and flow discharge data during years of 1973 to 2008 accumulated and analyzed. After determination of sediment rating curves in various methods, the best method was selected by comparison of the statistic parameters such as R, RMSE, r and GSD. After that, the daily sediment discharges in all statistic period were determined. At last estimating’s quintiles during 45 days period with the statistic indicator, relative mean of error. The results of this study showed that median of groups with R=0.79, RMSE=52148, r=0.68 and GSD=0.89 is the proper method for suspended load estimating in the Arazkoose station and based on this method the average of daily sediment discharge was estimated at this station as 11324 ton/day.

Because of importance of sediment delivery of watersheds, sediment rating curve is used for estimation of suspended sediment concentration. But most often sediment rating curve can not represent sediment concentration well in high flows, because of bias in log-transformation and extrapolation of data. For optimization of sediment rating curve, this research carried out with data of Q-SSC in outlet of two sub watershed of the Kamal Saleh dam watershed, Markazi province, Iran. Sediment data analysis was carried out using sediment rating curve of single-line and mean of classes with different correction factors such as FAO, QMLE, Smearing, MVUE and β. The results of various evaluation indices showed that the optimum sediment rating curve in the Hasan-Abad station follows single-line sediment rating curve and in the Ghaleh-No station mean of classes sediment rating curve, both with average of MVUE correction coefficients. According to the results, β correction factor for mean of classes’ sediment rating curve could reduce the difference between observation and estimation for high flows, but because of high scatter of observed data and undesirable extrapolation the Smearing-linear and QMLE had the lowest efficiency. However, for high flows in torrential events, the mean of classes’ sediment rating curve with FAO correction factor gave more accurate results than other methods.

Release of Zinc (Zn) is an important factor in determining Zn availability in calcareous soils. The kinetics of soil Zn release were investigated using 15 different soil samples collected from Golestan province by diethylene triamine pentaacetic acid (DTPA) solution. Different kinetic equations (Zero-and first order, parabolic diffusion, simplified Elovich and power function) were used to describe the rate of release of soil Zn. Comparisons of coefficient of determination (R2) and standard errors of estimate (SE) indicated that the power function, simplified Elovich and first order equations adequately described Zn release, whereas the zero-order equation did not. However, the first order kinetic equation inadequately described the release data at short reaction times. The Zinc release pattern based on the parabolic diffusion equation revealed that the rate of Zn release was higher in the first 2 hours followed by a slower release rate, which suggests that two different mechanisms are involved. The soil available Zn (released in rapid step) was included 40.5-83.3% of total Zn released in 192 hours.

Estimation and evaluation of crop water requirement is important key in scheduling, management and using from agricultural water resources. Many methods for estimation of phenomena are available that in this regard multiple modeling methods are prevalent. In this study Adaptive Neural Network based Genetic Algorithm and Co-Active Neuro-Fuzzy Inference System in side Artificial Neural Network for estimation of garlic evapotranspiration were used. For modeling from meteorological data including minimum and maximum temperature, minimum and maximum relative humidity, wind speed and sunshine hours and lysimeter data in climatology Station of Bu-Ali Sina University Agriculture Faculty during 2008-2009 for modeling were used. The garlic lysimeter Evapotranspiration maximum and average were 11.22 and 4.79 mmd-1 respectively. Results showed that Adaptive Neural Network based Genetic Algorithm were more accurate than Co-Active Neuro-Fuzzy Inference System. In other words, optimization of Artificial Neural Network more successful operation of fuzzy logic can be. Also, Artificial Neural Network was more appropriate to Co-Active Neuro-Fuzzy Inference System. So that Adaptive Neural Network based Genetic Algorithm than Co-Active Neuro-Fuzzy Inference System reduced 24 percent the testing error. But Co-Active Neuro-Fuzzy Inference System not only improves the results of artificial neural network was not, but reduced 12 percent the prediction accuracy. For the best architecture of Adaptive Neural Network based Genetic Algorithm, statistical parameters were RMSE= 0.12 mmd-1 and r=0.88. Coefficient of determination criteria, the width of the origin and the slope of line fitted to data estimated the Adaptive Neural Network based Genetic Algorithm model period (two years) compared with the Co-Active Neuro-Fuzzy Inference System model also showed, this model is efficiency.

Long-term effects of Rice (Oryza Sativa L.) cultivation with different management on soil P fraction are important to understanding from soil nutritional and environment point of view.Soil P fraction gives an idea about the soil supplying capacity to plants. This experiment was conducted to evaluate different soil P fractionation under paddy fileds condition and their relation with soil properties at rice root depth (0-30 cm). Soil samples were collected from 103 paddy fields at Some-e-sara city in Guilan provience with grids of 2x2 km. Soils were analyzed to determine of their characters (pH, CEC, T.N.V, Clay, O.C) and sequentialy extracted to determine organic and inorganic P fractions.The results showed total phosphorus concentration range between 218-1677.5 (mean of 563), inorganic phosphorus 60-1427.5(mean of 353 mg/kgsoil) and organic phosphorus with range of 25-525 (mean of 210). The persent of inorganic phosphorus were observed 62.6% of total phosphorus in comparison of organic phosphorus, 37.4%. Inorganic phosphorus fractionations in study area were Ca-p (mean=226), Al-p (mean=15.63), Fe-p (mean=220.4) and soluble and weak bounded phosphorus (Sol-p) (mean= 0.655 mg/kg soil), whereas the available phosphorus with mean of 29.02 mg/kg soil was more than Iranian paddy fields critical level. The Ca-p with pH, TNV, and OC%, Fe-p with pH, TNV, OC%, Clay content and CEC, Al-p with OC% and CEC, Sol-p with OC%, organic phosphorus with CEC, OC%, pH, TNV and Clay content available phosphorus with CEC, TNV and OC% showed significant correlation, respectively. The linear multiple regression equations the available phosphorus was affected from Al-p more than other fractions in rice fields.

In coarse-textured soils, because of possessing higher macropores, in general, water and nutrient holding capacity is low. The objective of this study was to investigate the effects of polyacrylamide (PAM), cattle manure (MR), vermicompost (VC) and biological sludge (BS) as soil conditioners on hydraulic and solute transport paramerers of a sandy loam soil. PAM (0.25 and 0.5 gkg-1 of air dry soil), MR (12.5 and 25 gkg-1 of air dry soil), VC (2.5 and 5 gkg-1 of air dry soil) and BS (1.7 and 3.4 gkg-1 of air dry soil) were mixed with soil and uniformly packed in to plastic pans (50 cm diameter and 25 cm height) and PVC tubes (15 cm diameter and 25 cm height) and then incubated in greenhouse at (0.7-0.8) FC moisture content and temperature of 22±4 ºC for 6 months. Plastic pans were used for soil sampling to construct soil moisture curves (SMCs) at 7, 30, 60, 120 and 180 days after start of incubation. Saturated hydraulic conductivity (Ks) and breakthrough curves (BTCs) were determined at the same times in PVC tubes. Van Genuchten-a parameter was obtained from fitting SMCs to van Genuchten (VG) model. Dispersivity (λ) parameter was obtained from fitting BTCs data to convection-dispersion equation (CDE). Van Genuchten-a parameter at both levels of PAM and second level of MR and VC was significantly (P<0.05) reduced. At both levels of PAM, compared with the control and other conditioners, Ks remained unchanged after 60 days of incubation relative to former times. All of soil conditioners decreased dispersivity (λ) parameter of CDE model. The findings of this study showed that PAM and MR were more effective than other conditioners at the used levels, in improving soil physical conditions.

This research, carried out in order to evaluation of the inverse distance weighting method and kriging, (ordinary and lognormal kriging) for estimate Organic carbon and Bulk density in paddy fields of the Iranian Institute of Rice Research in Rasht. Spatial variability characteristics of variables were determined by semivariograms. The function used for quantifying the structure of regional variable. Estimation of Kriging carried out by 6 than 40 neighbors in 70 percentage range of search radius. For estimation variable used to method inverse distance weighting of exponent value 1 than 5. The best models for organic carbon and bulk density were spherical. Four statistics of mean error, root mean square error, reduced variance and percent error were used to compare the methods. Exponent value was in the estimation inverse distance weighting for Organic carbon 1 and Bulk density 4. Results show that kriging is the accuracy better of inverse distance. Beside the best estimator was ordinary kriging for Organic carbon and lognormal kriging for Bulk density.

There are different mathematic methods to analysis and interpretation of water quality characters but water quality index is simple method and have several application. For investigation of water quality of Atrak river in golestan province, 6 stations for measuring of water quality in this river considered and measuring the water quality parameters has done in 3 times. Classification of water quality of this river has studied by NSFWQI, BCWQI index and said simple management methods. The Indexes show that except Ghazanghaye station that has good condition of water quality, the other stations have average conditions. The NSFWQI Index result show that most of stations have suitable condition and base on Said method, trivial management changing is necessary. Thus results of this two methods are alike but the result of BCWQI Index method that show from suitable to bad conditions, is stuffy.

Channel precipitation can be defined as rainfall and throughfall intercepted by the flowing stream channel and waterbodies, that without contribution to infiltration, subsurface flow, and ground water, incorporated into stream flow. Contributions of channel precipitation were studied in main river basins of Iran. The annual isohyetal map of the study area was converted to raster format and the average rainfall which falls on the streams and water-bodies surface were calculated, and converted to volumetric amount. The results indicated that streams and water-bodies' areas constitute 1.5 percent of the total country area. The results show that the amount of channel precipitation is 7.74 billion cubic meters, which represents 1.85% of total annual precipitation. The spatial pattern of volumetric ratio of channel precipitation indicates that its amount varies in different basins of Iran.