IRANIAN JOURNAL OF WATERSHED MANAGEMENT SCIENCE AND ENGINEERING
Year:2012 | Volume:5 | Issue:17|Papers Count:8

In the network of floodwater spreading and artificial recharge system, deposition is the main obstacle of infiltration water in the soil and reaching of water to the groundwater. Soil infiltration reduction depends on suspended material, the infiltration rate, soil physical characteristics and quality of the floodwater spreading. Fine-grained sediment enters into the network during the flood, reduce the efficiency of these projects and in long time of operation to actually lose its effectiveness. The main objective of this study is the effect of sediment deposited on the variation of infiltration rate by the floodwater spreading. In this study, double rings with triangular surface soil infiltration rate were used and the relevant data were entered into the Excel software. The analysis and comparison of the effects of the floodwater spreading on soil infiltration rate in comparison to control was evaluated using the statistical method of factorial completely randomized design. The effects of floodwater spreading on soil infiltration rate were evaluated using the statistics factorial method in completely design. Duncan mean comparison test was applied to compare rate of infiltration on spreading area with ditches between them. It is necessary to mention that the control values in the first year were compared with the results of reminder years. In general, the analysis of variances show the difference between rates of infiltration in depth of soil is significant at level 5% but the level significant for floodwater is 1%. There is no significant difference for interaction of these two factors.

In recent years, using fuzzy sets theory in modeling of complex and uncertain hydrological phenomena has attracted research workers. For this reason, in this research for river flow forecasting, we have used models of FIS and ANFIS which are based on fuzzy logic. Data of daily flow discharges were provided from Lighvanchay watershed for 6 years. For considering the randomness of data, return points test was used. Then correlogram of data was employed to determine the input optimum models and finally 5 models of discharge forecasting designed based on previous days' discharge. The results showed that ANFIS was more precise and less disperse (RMSE=0.0234) with compare to FIS (RMSE=0.1982). The ANFIS was also more precise in peak discharges simulation than FIS.

Landslides are the natural events that affect the various factors causing damage to nature, human and facilities. One of the susceptible areas of this natural process is Vaz watershed in North of Iran. For landslide hazard zonation Certain Factor, Information Value and Analytical Hierarchy Process (AHP) Models were used by applying GIS software. First the landslide distribution map was prepared by field observation with the map of different factors in landslides. AHP method was used for determining factors priority. Lithology, distance from the road, slope, distance from waterways and land use were the most important factors in landslide occurrence. In the next step, certainty factor, information value and AHP models used to preparing landslide hazard map in low, medium, high and very high classes. The validation of methods showed that certain factor, information value and AHP respectively have the highest precision in preparing the landslide hazard map.53.34% and 20.28% of the area located in high hazard and low hazard respectively, which indicate the high susceptibility of the area to landslide hazard.

Fire is one of the threats to forest and rangelands which affects different properties of ecosystems. However, effects of fire on infiltration and runoff production and sediment yield have been rarely considered in rangeland. This study was thus conducted to evaluate the influence of surface fire on amount of infiltration, runoff and sediment in rangelands of Kodir area, Iran. Towards this attempt, a rangeland area was selected in Kodir summer area where three 0.5´0.5 m-plot sizes were installed in control (no fire) condition. Three other plots with the same dimensions were also treated with fire in the same area. The study plots were then subjected to a simulated rain with intensity of about on millimeter per minute and droplet diameter of about one millimeter. The experiments were conducted one monthly basis for one year study period. The infiltration amount and it's variations in study plots were assessed using volume balance technique. The amounts of surface runoff and sediment were also determined in laboratory. The effects of the fire treatment on study variables and their interactions with time were then analyzed using ANOVA test. The results showed that the fire increased runoff and sediment in treated plots located in rangeland area with respective rates of 1.18 and 1.52 whilst a reduction rate of 1.014 was reported for infiltration in comparison to what recorded for untreated plots.

Marly units cover about 4438 square kilometers, i.e.20 per cent of Zanjan province territory. In this paper, the volume of runoff within marly units in Zanjan province was studied using a rain simulator.In this regard, by overlying slope, climate, and marly units of geological formation maps, a number of 18 homogeneous units were distinguished using Arc Gis 9.3 software and during field operations, runoff within 1*1 meter plots were recorded within each homogeneous unit, by incorporating a rain simulator and an overall of 220 plots were tested. Data collected from field operations, were analyzed on the basis of Randomized Complete Block Design with Factorial Treatment Structure, General Linear Method (GLM Model) procedure, F Test and Duncan Multiple Range Test.Investigation into the links between lag time, volume, and the coefficient of runoff within marly units suggested that the association will be described by a second power equation, by which trends of differences will be interpreted. The results of analyses showed that the effect of homogeneous units on the variations of lag time of runoff is significant, while the effect of climate is not significant. The effects of homogeneous units and slopes on volume and coefficient of runoff of marly units were significant, but, slope and climate factors had no effect on these two characteristics. A closer scrutinizing of averages showed, according to volume and coefficient of runoff, homogeneous units can be classified into four groups, on the bases of volume and coefficient of runoff of these groups, they were significantly different. The more silt content of soil, as a result of low or scant water holding capacity, the shorter lag time and larger volume of runoff is expected. The lag time of runoff, homogeneous units were classified into three groups. As well the effects of slope and climate on volume and coefficient of runoff of homogeneous units were also significant.

One of the goals of watershed management operations is preservation and restoration of welfare values of residents. Wetlands as a part of watershed are always important in viewpoint of ecosystem, environment and promenade. Protecting value of wetland includes the benefits obtained from conservation of non-use functions of the ecosystem. This study determined the protecting value of Gomishan Wetland in Golestan province using conditional valuation with double-bounded dichotomous choice questionnaire. For this purpose, the questionnaires were distributed among the visitors in 2010 after regional interview. The results indicate that the average people willingness to pay for wetland conservation was 6.58$ and 35.41$ per year for each person and household (5.4 person), respectively. The protective value of the wetland was estimated about 2520000$. Based on the result of the study, it is recommended that policy makers should improve the quality of ecosystem capabilities by allocating sufficient funding.

The knowledge of water balance and soil moisture variations is one of the important problems in water harvesting issues. At the present, there are different methods available for soil moisture measuring. Considering that the current methods of soil moisture measuring are time consuming, thus using the time domain reflectometry system is widely used in the world. At the present, by considering high cost of buried sensors and a need to use of many of them in the projects, it is important to construct sensors with high accuracy compared to foreign sensors with a suitable cost and possibility of purchasing by other scientific institutes in Iran. Thus, various types of steel rods were provided to reach the most suitable samples. In this step, the measured soil moisture was compared to foreign sample to assess the constructed samples. Statistical analysis using SPSS programme showed a high R2 value (99%) with the similarity of constructed and foreign samples. In the next step, the results of manufactured and foreign type samples were compared to measured soil weigh moisture. The results of analysis demonstrate the good function of constructed sensors. Statistical analysis showed high statistical significance and R2 (99%). Based on the results of this research, it is possible to provide a suitable condition for the Iranian researchers for implementation of the projects.

Soil erosion will cause nutrients washes out, soil depletion and water pollution. Therefore, information on nutrient loss variations and its transport in surface water is very important. The present study was conducted to analyze phosphorus losses in 5 rainfall events and the relationship between the hydrographs and the phosphorus pollutographs in Kojour watershed. Results showed that maximum and minimum phosphorus loss were 32126 and 6707 g, respectively with an average value of 2620 g. The results of pollutographs were also showed that most of the pollutographs are in advanced and developed stages and rating loops also recognized as clockwise type. The results ultimately approved the necessity of further detailed studies in storm scale and different time bases.