IRANIAN JOURNAL OF WATERSHED MANAGEMENT SCIENCE AND ENGINEERING
Year:2010 | Volume:4 | Issue:12|Papers Count:8

The main objective of this research was to study the factors affecting the rate of rural people participation in watershed plans in Jiroft region. The kind of research method of the study was Descriptive- Correlation research. The statistical population of the study consisted 1660 rural persons in 32 villages of Jiroft region in which watershed plans have implemented during the years of 1999 to 2006 (N= 2122). According to the Cochran's formula, a sample of 228 persons was selected using the stratified random sampling method (n= 228). A questionnaire was used to collect the data. The validity of the questionnaire was established by a panel of experts in the field of participation and rural development. A pilot study was conducted to establish reliability of the instrument. Cronbach alpha's coefficient for the dependent variable (e.g. rate of rural people participation in watershed plans) calculated 0.88. For data analysis was used SPSSwin15 software. The correlative results revealed that there was a positive and significant relationship between dependent variable with variables of education level, satisfaction, social solidarity, socio-economic situation, motivation and membership in social institutes, travel to out of village, agricultural experiences, garden and agricultural land ownership, using the information resources, income level through agricultural activates, receiving the incentives, agricultural cultivated land and activity of rural councils. In addition, there was a negative and significant relationship between dependent variable and government dependency. Based on Regression analysis, 46.8% variances of dependent variable of rural people participation in watershed plans was explained by the five variables including: social solidarity, using the information resources, gardens and agricultural land ownership, level of satisfaction, membership in public rural institutions.

Considering the overuse of the aquifers and flow regime of ephemeral rivers of the country, performing artificial recharge projects in these rivers is necessary. Although, there have been a considerable number of researches in the artificial recharge system, there has been no method for determining the recharge efficiency of the artificial recharge systems on ephemeral rivers yet. The goal of this research is to determine the recharge efficiency of the artificial recharge systems by using the flood flows of ephemeral rivers. In the suggested method, the first step is dividing the flood hydrographs of different return periods using model between different parts of the system. So the intake efficiency of ponds is determined. Then, according to the dimensions of recharge ponds and the penetrated water during the flood, the amount of water that can be recharged may be determined using seepage formula. For determining the river bed infiltration, a combination of hydraulic modeling using Hec-Ras simulation and Etcheveri method has been used. Finally, after determining the recharge efficiency of system for different return periods of flood, the total recharge efficiency of the system is determined by calculating the expected value. The suggested method is applied for the artificial recharge system of Emamzade Abdollah River of Semnan, in center of Iran. The results show that the presented method has suitable recharge efficiency and is able to use 81% flood flow for artificial recharge.

Many factors like topography, climate, geology, tectonic, vegetation, soil properties,… are effective for occurring mass movements, that some of them are natural and some are created due to human activities. Deforestation and degradation of forests is one of the factors that aggravate the landslide occurrence and create mass movements directly. To investigate this important problem, in this research, two hillslopes with the same conditions (from viewpoints of geology, pedology, topography and climate) in the field (Ardal township- Chahar Mahal & Bakhtiari province) were selected as one of them includes deforestation (unstable) and another one has been covered by oak forest and is stable. Based on the studies, both hillslopes have been located in alluvial formation with marl layers and soil texture in both of them is also clay-loam that dominant mineral clay is esmectite. From point of view of soil mechanical properties (internal friction angle and soil cohesion), both hillslopes are the same and they classified in ML-CL groups. From the hydrology view point, water resources in upstream of both hillslopes are common and the rate of infiltrated water is 152600 cubic meters per year. The most difference between these two hillslopes is the vegetation percent as one of them has been covered by oak forest with 40 percent canopy while other one (unstable hillslope) has less than 5 percent canopy. After determining the all effective parameters in landslide, it was specified that in landslidy hillslope, the factor of safety is equal 1 (Bishop Method) and hillslope has been slided. On the other hand, in hillslope with oak trees, the rate of safety factor (without considering the effect of tree roots) has been obtained equal to 0.9 and hillslope is stable yet. Then, it can be concluded that oak trees with 3-4 root depth, have increased the soil strength and its consolidation. Furthermore, oak forest has been able to extract the further water and decrease the mass weight through increasing the evapotranspiration. Finally, it can be concluded that in Zagros region, deforestation and cutting the oaks is one of the important factors for occurring landslides.

Estimation of rainfall spatial distribution is an important step in water resources studies. Preliminary assessment of existing rain gage networks show that the spatial distribution of the gages is not suitable as many are just located in populated areas. Optimization of rain gage locations can improve the accuracy of water balance studies. Several methods have been proposed for such tasks. Kriging is a geostatistical method which can estimate the variance error based on a pre-determined semivariogram with no reliance on historical record. One can therefore apply Kriging method to estimate the reduction in error variance due to any change in the network such as addition of a new gage or moving an existing gage. In this paper, the objective is to optimize gage locations based on error variance and topography of the region. This is done such that no extra cost is incurred; i.e. only omission or moving the stations is allowed. The results indicated that the number and the network structure is sufficient for estimation of rainfall distribution in dry months. However, in case of wet months and the annual rainfall, moving some of the stations is necessary. In all, 17 stations may be moved to reduce the average error by 10 percent. It must be noted that the error is quite high in extrapolation regions, as expected.

Seasonal rainfall forecasts can have significant value for resources planning and management e.g., reservoir operations, agricultural practices and flood emergency responses. To mitigate this, effective planning and management of water resources is necessary. In the short term, this requires a good idea of the upcoming season. In the long term, it needs realistic projections of scenarios of future variability and change.In this paper, we analyzed 38 years of rainfall data in Khorasan-e Razavi province that is located in the northeastern part of Iran situated at latitude-longitude pairs (34o-38oN, 56o- 62oE). We attempted to train Mamdani Fuzzy Inference system based on Tele-connection synoptically patterns with 38 years of rainfall data. For performance evaluation, the model predicted outputs were compared with the actual rainfall data. In this study, at the first step, the relationship between synoptically pattern variations including Sea Level Pressure (SLP), Sea Surface Temperature (SST), Sea Surface Pressure Difference (SLP), Sea Surface Temperature Difference (SST), air temperature at 700 hpa, thickness between 500and 1000 hpa level, relative humidity at 300 hpa and Precipitable water have been investigated. In the second step, model was calibrated from 1970 to 1997. Finally, rainfall prediction is performed from 1998 to 2007. Simulation results reveal that Mamdani Fuzzy Inference system techniques and regression models are promising and efficient. Root mean square for Mamdani fuzzy inference system model and regression model was obtained 6.34 and 5.5 millimeter, respectively.

Bottom outlets are series of structures that were used to convey water from dam reservoir to the downstream. Accordingly, because of the importance of Bottom Outlet Systems in dams, analyzing the performance of conduit, gates and outlet is considerable. The existence of high-pressure flow in the bottom outlet channel, the various kinds of head losses and the small amount of opening height versus the reservoir head over the gate cause considerable errors in the required mathematical methods and relationships.Therefore the need for laboratory studies in this regard is essential. The purpose of the present study is to determine hydraulic capacity of Narmasheer Dam Bottom outlet Narmasheer the lower dam using data obtained from physical model.In this research, the physical model of bottom outlet system of Narmasheer Dam including conduit, gates (service and emergency) and outlet was designed and constructed at SCWMRI (Soil Conservation and Water Management Research Institute) lab, and then the necessary tests have been performed.The different amounts of pressure heads and water discharges in various gate openings were measured for 6 different head of reservoir and 12 opening gate.The results showed that the trend of service gate discharge Hydraulic coefficient changes at maximum head, from 2 to 10 percent gate opening, had an increasing rate and for 10 to 30 percent opening, had a decreasing rate and then from 30 to 70 percent opening, the rate of discharge coefficient was the highest this trend was also observed in other elevation. Therefore, the rate of change of discharge coefficient at two low elevations from 50 percent and higher will start the changes of Froude number showed that with increasing the level of reservoir, Froude number will increase and at fixed level of reservoir, with an increase of gate. Opening Froude number will decrease. This process also tested other heads of reservoir be seen, but trend coefficient changes in two head lower, from 50 percent opening gate, begins to increase. Overall change in coefficient showed an increase amount of valve coefficient opening gate, be increased.Investigation of the discharge change showed with increases in opening gates, the rate of discharge will increased.Froude number changes showed with increase amounts of head reservoir tank Froude number will increased, and in fixed of head tank, with increasing the amount of valve opening gate Froude number will reduced.

One of the methods to forecast peak discharge among black box method is artificial neural network. Lack of emphatic regulation to architect network is one of disadvantages in neural networks. There is not a suitable criterion to determine number of layer and number of neuron in hidden layer, type of activation function for hidden and output layers and assay and error method is the only solution. In this research, numbers of suitable neurons in this layer and activation function type in output layer for two sub basin, Gatehdeh and Gelinak, situated in Taleghan basin were investigated by perception neural network with three layers and preservation of type of activation function for hidden layer. 20 percentage data for testing stage, 65 percentage data for training stage and 15 percentage data for validation stage were entered in MATLAB software and sigmoid and linear activation functions with the most application in hydrologic subjects were selected for output layer. Linear function with less RMSE in both stations recognized suitable and the numbers of adequate neurons in Gatehdeh and Gelinak stations were five and six neurons, respectively.

River banks are exposed to destruction and bank erosion. Providing human requirements and reduce river's dangers is one of the river engineering's purposes. The extent and risk of this phenomenon must be recognized. Groin is suggested as one of the control methods to reduce erosion. Besides, it is helpful way to reclaim lands. Groin's length has effective influence on bank erosion control. Laboratory models were used to investigate river protection and reduce bank erosion. Tests were done in 3 groin's lengths and 5 discharges. Results show that increasing groin's length from 25 up to 35 cm, and discharges from 15 up to 25 lit/s can reduce bank erosion about 20-40 percent.