پژوهشنامه مدیریت حوزه آبخیز
پیاپی 14 (پاییز و زمستان 1395)

This study was done to simulate runoff of Gorgan city using of the hydrologic-hydraulic model SWMM. In this study¡ to calibrate the model¡ four rainfall events¡ were used and the speed of the corresponding runoffs in the chosen sub basin were recorded. In this study¡ NS¡ RMSE and BIAS% were used as model performance indices in the estimating peak discharge and flow volume. Also significant and no significant differences between the observed and simulated values by paired t test were investigated. The model calibration results showed that the simulated peak discharge and flow volume are in good correspondence with the observed values (BIAS%= 11.44¡ RMSE= 0.006 and NS= 0.70) and the calibration results were used for the optimum values of parameters. To evaluate and test model validation¡ two rainfall events¡ were used. That the model performance indices were acceptable in both cases (BIAS%= 8.01¡ RMSE= 0.00043 and NS= 0.69). Furthermore¡ according to paired t test of difference between observed and simulated values in the calibration and validation of the model error (0/01 or 0/05) are not significant. The results of the study indicate that the model has the accuracy required for urban runoff simulation.

The maps of potential flooding areas can be the appropriate tool for urban planning in the future. In this research, potential flooding areas criteria viz. the urban land use, distance of river, elevation, slope and ground water level were considered. The weight of decision criteria were evaluated by paired comparison matrix. The final potential flooding map was divided to five different risk classes. About 15 percentage of the study area were belongs to very high and high risk classes. Including areas located in high risk near to the river, impermeable areas, low topography and slope less than two percent in these areas. Focus on areas with historical flood events showed that areas with slope less than two percent are more affect by flood. The results of the Analytical Hierarchy Process showed that ten percentage of the area with historical flood events is located in very high and high classes. The results show that percentage of the class area with high and very high risk according to historical flood events are 43, 34 and 26 percent for gaussian, triangular and generalizedbell-shaped membership functions, respectively. The result of Gaussian membership function is more similar to historical flood events reports.

Flood is one of the natural hazards that its frequent occurrence has increased in the recent years and the damages of it, had affected apart of country in every year. Prioritization of sub basins has an important effect in watershed management. The purpose of prioritization of sub basins is offer a pattern for control and decrease flood hazards and evaluating the role of each sub basin in peak discharge of outlet flood hydrograph of basin. In this study, NEKA basin was selected as study area, because of several floods was occurred in it and with combining GIS and HEC-HMS hydrological model, the contribution of each sub basin in outlet flood from total basin based on SCS method, was determined. For this purpose, at first design rainfall hyetograph for different return periods was computed and after calibration the HEC-HMS model and estimate optimal value of the parameters, outlet flood hydrograph from each sub basin of NEKA basin and also outlet flood hydrograph from all over the basin for different return periods was simulated by HEC-HMS. For prioritization of sub basins, after removal of single sub basin in HEC-HMS environment, two indexes of parcenary contribution of each sub basin in outlet flood of basin and parcenary contribution of each sub basin in outlet flood of basin per unit area was used. for this purpose, the 100 years return period flood was used. The results showed that the contribution of sub basins in flooding potential will be not only affected by its area but also the place of each sub basin and flood routing in main reach have remarkable effect on flooding regime of basin. Also determine the severity of flooding per unit area of sub basins, in prioritization flood control operation for cost and facilities, can be more efficient than other. Finally was observed, the sub basins that are located in the central part of basin, have most effect on the total basin's flooding.

Today, one of the major problems of flood control projects is watershed prioritizing for resource allocation and structural and non-structural practices. Due to the lack of hydrometric stations in many watersheds, is difficult determining the participation of sub catchments to create flood. So study the affective factors in watersheds through models such as multi-criteria decision analyzing system (MCDAS) can help to determine the role of each sub catchment in creating flood. Despite the frequent occurrence of floods in Sector watershed, it has not any hydrometric station. The purpose of this study was to evaluate the potential of sub catchment in creating flood. In this study after providing digital layers of factors such as area, slope, main channel slope, drainage density, form factor, annual rainfall, land use and the infiltration of sub catchment, the AHP method was based to measure weight of each layer Finally, by applying weights and coefficients of each layer in MCDAS extension in ArcGIS, a combination map was produced. Pixel values of combination map can be varied from zero to one that it has much potential of flooding. According to the final map, the C'5 sub catchment has 0.79 value that has the greatest potential flood risk and it should be a priority for corrective practices. Next, C1 and C2 and C3 were at the high risk groups and C'7 and C'3 were at low risk group of flooding and C5 sub catchment with 0.15 value has the lowest risk of flooding in the region.

Regional analysis is the stability method to improve estimates of flood frequency, which has become one of the dynamic sectors in hydrology and the new theories are testing, constantly. Application of geostatistical method is an innovation in this field for regional flood analysis.This technique is based on the interpolation of hydrological variables in the physiographical space instead of using common geographical space. However, the hydrological, climatological and physiographical information of 38 river basin information of watersheds inside of Mazandaran province were obtained and Canonical Kriging method was used for regional flood analysis whit return periods of 10, 20, 50 and 100 years. The Canonical Correlation Analysis was used to design physiographic space by the geomorphoclimatical variables affecting the flood. The Gaussian model had the best fit to semi-variogram model in all return periods and the geostatistical method of Ordinary Kriging was used for regionalization. Results evaluated using Jack Knife mutual procedure and the five statistical indexes. The performance of NASH was obtained over than 0.9 in all of return periods, which implies the accurate and acceptable predictions of flood in ungauged basins. The other indicators led to satisfying results, too. According to the results of relative statistical indicators accuracy regional estimates improves as long as return periods increase. These results showed that application of Canonical Kriging method is effective and practical approach for regional flood analysis.

In this study, the ability of spatially distributed hydrological WetSpa model for simulation of suspended sediment concentration in a daily time step was investigated. Hydro-climate daily data for a period of 7 years including: precipitation, temperature, evaporation, discharge and suspended sediment and three basic basic digital maps of DEM, soil texture and land use, with the cell size of 25 meters was used. Also, with the implementation of the model by changing the land use map, we determined the impact of land use change on sediment of GolGol watershed. The results showed that the WetSpa model has potential to simulate suspended sediment concentration at the daily time step based on Nash-Sutcliffe (%67.45) as an important evaluation index. Moreover, the change detection of land use showed that by changes in forest and irrigated agriculture-garden from 1988 to 2013 there is a reduction amount of 3322.5 and 3934.3 hectares respectively, while, for rangeland and dry farming increased 3942.99 and 3313.9 hectares respectively. The results showed that the mean daily sediment concentration, annual specific sediment and annual suspended sediment yield by changing land use from 1988 to 2013 has increased. Statistical analysis results showed that the land use changes have effect on suspended sediment concentration in 1% significant level in the study area, so that the mean annual sediment concentration of 1.141 g/l in 1988 increased to 1.171 g/l in 2013. Finally the yearly average of sediment yield increased 63.8189 kilograms per hectares.

Despite of soil disturbance, transfer to the laboratory and preparation inside the plots which themselves lead to lower validity of the results, the experimental study on runoff and erosion at plot scale with many research advantages are inevitable. However, there has been less attention to evaluate the effects of soil preparation on runoff and sediment variables. The present study was therefore conducted to compare surface runoff in two undisturbed (natural) and disturbed (during various steps of preparing soil for laboratorial studies) soil conditions. To achieve the study purposes, 1×1 m-plots were considered in a slope with sandy-clay-loam soil and gradient of 18% under simulated rainfall with three intensities of 40, 60 and 80 mm h-1. The study slope was located in the vicinity of Kodir village in upper Educational and Research Forest Watershed of Tarbiat Modares University. The time-to-runoff in the output of each plot was recorded and the runoff volume and coefficient at five three-minute intervals was subsequently measured. The results showed that the average time-to-runoff, runoff volume and coefficient were significantly (p≤0.01) increased 2.29, 3.45 and 2.79 times, respectively due to the soil disturbance which clearly indicated the impossibility generalization of laboratorial runoff and erosion results to natural conditions without considering the effects of soil disturbance. The results showed the synergistic interaction of soil disturbance and rainfall intensity on time-to-runoff and antagonistic interaction on runoff volume and coefficient.

Mass movements are usually natural erosion, but the human can aggravate it by operations such as mining, road construction and destroying the natural vegetation. The purpose of this study is to identify the factors influencing the occurrence of landslides by using a probabilistic model Weight of Evidence and Geography Information System in the Siyahbisheh Watershed. 132 landslide points are identified and recorded through interpretation of aerial photos and wide field surveys. Randomly out of this number, 92 landslide points (70%) for modeling and 40 landslide points (30%) are implemented for evaluation. The factors studied in causing landslide includes slope, aspect, plan Curvature, elevation, distance from the road, distance from the streams, distance from the faults and geological survey using GIS digit and maps are provided for each of the factors. The relationship between each factor with landslide points is determined by using a probabilistic model weight of evidence and the landslide susceptibility map is provided.WOE model introduces classes, 30-15slope degree, aspect of northeast, the elevation of 2200-2600m,150-200m distance from the road, less than100 meters from the road, distance of more than 400 meters from the fault, the geological formations Jurassic-Triassic, concave curvature as the most important factor causing landslide in the Siyahbisheh Watershed. The results of ROC curve analysis showed that the WOE model with the AUC 0.81 has an acceptable accuracy for landslide susceptibility analysis in the study area.

Environmental hazards are considered as one of the factors threatening human societies. Identification areas susceptible landslides risk assessment of natural hazards and management of are the essential steps in the city's watershed. The purpose of this study is landslides hazard zonation in Izeh urban watersheds of East Khuzestan. In this research First, eight layers effective in landslides, including: geological formations slope, elevation, rainfall, distance from drainage, land use, slope and distance to faults in ARC GIS digital and were classified, Then using CRITIC were weighted layers. The next step was to standardize layer using fuzzy function; and were imported the models. Finally landslides hazard zonation maps by using two models of multi-criteria models (TOPSISS, and WLC) were prepared. These maps are susceptible to landslides Each of those class into five regions with very low to very high risk were. Classified. The results of models show that for TOPSIS 122.99 km from the area is high to very high risk and 89.5 km very low to low risk is. While WLC model 76.13 km from region in high to very high and143.03km in low to very low risk class. Comparison of the models shows that the TOPSIS model is more zones at risk earthquake is show. According to the field research and studies in the IZEH area seems WLC model is closer to reality. Consequently WLC model has perform better than TOPSIS model for landslide hazard in this region.

Accurate estimation of the sediment volume carried by the rivers is important in water related projects and recognition and suggestion proper methods for estimating suspended sediment goals which should be conducted by related researches. Among the methods that have been recently used to model suspended sediment, machine learning based methods such as decision trees, support vector machine, and artificial neural networks are importance. In the present study, the applicability of such techniques in predicting suspended sediment load of Babaaman watershed in Bojnord, Iran has been evaluated. Input data for predicting Babaaman watershed’ suspended sediments in this project are: Debi, suspended load, raining and evaporation, which are related to the statistical period 1349 to 1380. In order to assess the accuracy and precision of the model results, statistical measures including R, RMSE, and MAE have been utilized. Consequently, the results of statistical value of R and RMSE for sediment rating curve method 0.80 and 55863.77, neural network 0.98 and 1.28, decision tree model 0.96 and 48881.56 and support vector machine 0.99 and 0.6998. The obtained values reveal that the support vector machine was more consistent with the measured values compared to the above-mentioned methods.

Rivers are highly sensitive to environmental changes. Detection of river changes can lead to recognition and optimal management of the river channel side and riverbeds. This study aimed investigating the river changes and identifying the factors affecting the level of channel side of Babolrood in Babol City. The data of this study were collected from river discharge and sediment, land structure and substances along with aerial photos of year 1335 and SPOT satellite images of year 1393 in Google Earth software. To determine changes in the channel sides, transect method was used in this study. The temporal and spatial changes of both sides of the Babolrood channel side were compared to baseline and calculated by locating a straight and constant line as a baseline and a transaction at intervals of 200 meters. Channel changes were numbered in four separate intervals and finally the changes of left and right banks of Babolrood were studied and analyzed by overlaying and integrating the two time periods. The results of this research indicated drastic channel changes in the last 60 years of Babolrood River. The following factors had a remarkable role in Babolrood channel side changes: elimination of barren usages, reduction of other usages to the benefits of residential ones and fluctuations in discharge rate and river. In addition, the contribution of fault in the movement and the length of channel side should not be ignored.

Self-Organizing Feature Maps (SOFM) are a variety of artificial neural networks that their applications in the areas of pattern recognition and data clustering makes them noticeable tools to perform regional flood frequency analysis (RFFA). In this study, ability of Self-Organizing Feature Maps for regionalization of Sefidrood watershed in order to perform regional flood frequency analysis using L-moment algorithm is assessed. Results of this study show that SOFMs may be used as an acceptable method for data clustering and regionalization of watersheds. Evaluation of values of cluster validity measures showed that they can’t be a determining factor to identify suitable number of regions for regional flood frequency analysis, but homogeneity of regions is main factor to determine desirable number of regions. According to homogeneity of regions and sizes of formed regions, regionalizations including two regions that formed by Ward’s algorithm and SOFM were chosen as optimum choices to regional flood frequency analysis on Sefidrood watershed. Furthermore, based on results of flood estimation by at-site FFA and two RFFA, regional estimates are very close to each other and their average relative difference is equal to 1% nearly. Also relative difference between regional and at-site estimates doesn’t exceed 17% in any station and its mean value is about 8%.

The flow duration curve (FDC) is a classical method used to graphically represent the relationship between the frequency and magnitude of stream flow. Several factors are involved in the shape of (FDC), including climatic and physiographic parameter of basin. In this research, the relationship between (FDC) and the physical parameters of the basin were investigated. 20 hydrometric stations with appropriate daily data were selected. Physiographic parameters extracted using the GIS capability and Flow duration curve were plotted using daily flow data. The first and last inflection of the curve was computed, using coding in MATLAB programming environment. Factor analysis was performed and the most important independent factors influencing the form of flow duration curve were identified. The homogeneous analysis based on independent factors, using cluster analysis method was investigated. Finally correlation between the exceedance values at the inflection point and the geometric and hydrologic parameters were investigated. The results showed that the parameters of the perimeter, Area, length of Main River, length of the catchment, the time of concentration, and the average height of the basin were the most important factors affecting the shape of the curve in the study area. All above mentioned parameters has a positive correlation with deformation curve Index. Precipitation was found as the second most influential factor, with a negative correlation.

Evaluation of climate change and its possible consequences on hydrological processes in catchment will help to the challenges of water resources managers and decision makers in the future. One of the common tools for evaluating of this event is utilization of rainfall-runoff model to simulate the hydrological process. The aim of this study is to investigate effects of climate change on runoff and drought and flood events in the period 2040-2069 in Neka basin. In this study, a semi- distributed model for evaluating the impact of climate change was used on hydrological processes for Neka basin. in this approach, first the parameters of a continuous semi- distributed model SMA calibrated for the period 1981-2010, then in order to evaluate the effects of climate change on basin hydrology during 2040-2069 using Hadcm3-AR4 climate model data under A2 emissions for the region downscaled and downscaled data has presented to the SMA model and then changes of runoff were evaluated in future period. Comparison of observed and simulated climate parameters by climate models for the period 2040-2069 shows that the temperature in different months between 1.41 to 3.47 degrees Celsius warmer than the base period. Precipitation for the cold months has increased by about 23 percent to 25 percent decreases in the warm months. Also, the results of drought and flood frequency show that 7- day low flow decreased by 7% for the 200 years return period in 2040-2069 to 1981-2010 periods.

According to the importance of this issue in present study first using of time series data of years 2006-2012 and RCM-PRECIS simulation model the impacts of greenhouse gases emission on climatic variables temperature and precipitation under different scenarios in watersheds of Qazvin province was investigated. Then, in order to assess the impacts of climatic variables temperature and precipitation on selected products yield from ordinary least squares (OLS) method and regression analysis was used. In followed, by consider the result of regression analysis in positive mathematical programing (PMP) model the amount of the created variation in supply and demand of irrigation water and agricultural output in watersheds of Qazvin province was investigated. The results showed that emission of greenhouse gases under scenarios A, B and C affects the climatic variables temperature and precipitation about 0/43 to 1/27 °C and -14/1 to 1/31 mm. This case changes selected products yield in the surface of each river basin of Qazvin province. Change in yield affects acreage of agricultural crops about -10/51 to 3/17 percent, the amount of irrigation water supply about -10/4 to 1/64 percent and the amount of irrigation water demand about 1/60 to 7/35 percent. Also, the results showed that maximum and minimum decrease in the gap between supply and demand of irrigation water happens in Kharroud and Shahroud watersheds and about 9/20 and 1/82 percent.

Fluctuations in the meteorological variables such as: temperature, precipitation, is one of the atmospheric circulation characteristics. Meanwhile, the sharp decrease of precipitation and dry periods caused by that has many negative effects on water resources. Climatic fluctuating in a region has severe effect on soil and water resources. Nowadays, generally it has been accepted that any change in climate system is important in the water and soil resources management. Among the climate elements, precipitation has the most fluctuation; this matter especially in Iran that the average rainfall is 250 mm is more importance. Drought and wet periods, especially drought period has been affected the Kaju watershed for a long time; and because of its long durability has been exposed to a lot of damages and injuries. The purpose of this article is Investigation of temperature, precipitation and discharge change trend the basin watershed a period of 20 years. Mann-Kndall parametric test was used to determine trend parametric. The results show precipitation decrease trend, temperature is ascendant trend and discharge River region is decrease trend.

Well designed monitoring networks are essential for the effective management of groundwater resources but the costs of monitoring well installations and sampling can prove prohibitive. The challenge is to obtain adequate water quality and quantity information with a minimum number of wells and sampling points, a task that can be approached objectively and effectively using numerical optimization methods. Unfortunately, aquifer systems tend to be complex and monitoring can be very expensive, particularly when it requires the installation of a dedicated network of monitoring wells. In recent years, the challenge has been to design monitoring networks that are both efficient and cost effective. With regards to groundwater monitoring systems, where the challenge is to maximize the availability of good quality data while minimizing the number of sampling sites and thereby limiting costs, optimization techniques clearly have a potentially valuable application. In this paper we use a site in northern Iran to test the ability of GA, when used in combination with Kriging, in comparison with PSO to lower the cost of a monitoring network by reducing the number of monitoring wells without compromising the quality of the interpolated data. The results of the optimization showed that the number of observation wells in the Astaneh aquifer monitoring network could be reduced by 26% from 57 to 42 without a significant loss of information. The root mean square error (RMSE) for the final optimized network in GA was 0.2025 m, that in PSO 0.3222 m. A comparison of RMSE values determined using the GA algorithm with those calculated using PSO algorithm technique showed good agreement and provides strong support for more efficient GA approach.

Erosion rate has temporal variability and shows a cyclic fluctuation in each year as well as the factors influence it due to the seasonality of climate. This study was done to determine the seasonal variability of rainfall erosivity and suspended sediment and also to found out critical times in term of erosion risk in Kasiliyan watershed. The appropriate indices of monthly rainfall erosivity were determined for the aforementioned watershed based on regression analysis between EI30 and several easily accessible indices for 27 rain gauges inside and around the watershed. Finally, monthly maps of erosivity were produced by Kriging method. For estimating the suspended sediment, we used a combination of sediment rating curve of mean loads within discharge classes and average daily discharge data. Then, correlation between monthly sediment loads and corresponding erosivities was investigated. The results showed a strong seasonality for both rainfall erosivity and suspended sediment. Two peaks were observed in annual erosivity/precipitation in Kasilian basin, one in the late fall in Aban and Azar (Iranian month equal to Oct. 23 to Nov. 21) which was 41 MJmmha-1h-1 and another in spring in Farvardin (Iranian month equal to Mar. 21 to Apr. 20 which was 24 MJmm ha-1h-1(. A change in precipitation type (rain to snow) due to the change in temperature is a possible reason for lower rainfall erosivity during winter. In contrast, the suspended sediment showed just one peak during spring in Farvardin (equal to Mar. 21 to Apr. 20 which was 13175 ton). Absorption of early rains by dry soils in the fall is most probable reason for little runoff and consequently low rate of sediment (3300 ton during Aban) in the outlet of watershed.

The studied area in this study is Marand plain with an area equivalent to 517.42 square kilometers in the North West of East Azerbaijan province. In this research, consecutive periods of meteorological and hydrogeological droughts were detected by SWI and SPI drought index at 6 periods (6, 9, 12, 18, 24 and 48 months). For this purpose was used monthly precipitation mean of 7 rain-gauge stations in period (1980-2012), Water quality data of 70 wells and monthly water levels data of 23 piezometers wells in period 2001-2011.Results of SPI index indicated that in the studied area, severe drought has occurred in 2007 year and regional wate/r requirement has not been supplied until the end of the studied years. Also SWI index results is indicator of increased extraction of groundwater for compensate of plain water requirement that have been followed fell about three meters of groundwater. Pearson's correlation between the meteorological drought and groundwater levels is significant at the 1% level of confidence and show influence of groundwater resources with a 5-month delay. Quality of groundwater chemistry based on the electrical conductivity (EC), sodium adsorption ratio (SAR) and chlorine (Cl) showed that Changes in water quality in a wide range of Marand plain has been occurred cause of increasing the area under cultivation and increasing extraction. The results obtained from diagram Wilcox showed that about 44 percent of the area of groundwater Plains is in classes C1S4 to C4S1 and is a salty for agriculture.

Estimated time of concentration is one of the most important topics in the study of watershed physiographic and hydrology and relatively accurate estimates of that effects on other hydrologic parameters, including peak flood discharge. Despite numerous empirical formulas and widespread application in Iran, up to now a study hasn’t been done about the best relationship and important physiographic parameters and the effectiveness of theirs increasing or decreasing of concentration time, in Gheshlagh Dam basin. So in this study, in addition to study the sixteen relationship of concentration time that have extensive application in our country, a method was presented for the path coefficient analysis of important physiographic parameters of concentration time. In this regard, first Using real-time concentration of trace amounts of dissolved salts, the accuracy of concentration time was assessed by RMSE and MRE statistics methods and the best empirical equations was selected. Then using the Path Analysis method, direct and indirect impact of ten important parameters of basin on concentration time was determined. The results showed that in Gheshlagh Dam basin between investigated relationships, California and Bransly Williams formulas are the best equations for estimate time of concentration (mean error relative to 41.1 and 43.5 percent). Also Chaw and Janson kroos have mean and acceptable result (mean error relative fewer than 57%). The path analysis results also showed that the stream length parameter have the most positive effect (1.10) the area of basin have the most negative effect (-0.257) on time of concentration.

In Nash's cascade model that is simple and efficient model for simulating hydrological response in watersheds, catchment behavior is considered same as n linear reservoirs with k storage coefficient. In this context, the accuracy of different methods of estimating the Nash model parameters (n and k) including moment, experimental Nash formula, Han’s graphical, time to peak-time to inflection point and Bhunya et al methods have been investigated in Manshad watershed in Yazd province. The n and k parameters were calculated using three storm events and physiographic parameters were used for experimental Nash formula. The mean value of calibrated parameters, were used for simulation of second subset of storm events as model validation. The results show that using Bhunya and Han’s graphical methods for n and k parameters estimation, lead to better agreement between observed and simulated hydrographs. Percentage of relative error in simulating peak discharge, time to peak and flood volume, in Bhunya method, were estimated equal to 28.24, 29.48 & 8.20% and in Han’s graphical method were estimated equal to 28.29, 29.48 and 8.52% , respectively. Also, the results indicate that time to peak-time to inflection point method and experimental Nash formula give weak results for simulating some flood characteristics. Thus, using these methods in similar catchments is not advised without more researches.

Underground dams are structures that block the natural flow of groundwater and causes underground water resources. In this study, at first18 prone area stounderground Dams were identified using Boolean logic and geology parameters, land use, slope, distance from roads and distance from fault. In the discussion of underground dams, subsurface flow has high importance so that if there is not suitable subsurface groundwater flows construction of underground dams may fail even with high costs. Therefore in this study, SWAT model was used to simulate the water balance and subsurface flow in Doroongar watershed andit was identified using those areas which have suitable subsurface flow and this parameter was used to zone and prioritize the prone areas. By running the SWAT model in the Doroongar watershed, in the calibration step, the correlation coefficient, weighted correlation coefficient and NS (Nash Sutcliffe) were calculated 0.77, 0.75 and 0.68, respectively and in the validation step were calculated 0.71, 0.67 and 0.61.The results showed that SWAT model had acceptable performance for simulation in Doroongar watershed. The results of subsurface flow simulation show that north and south parts of the Doroongar watershed has higher subsurface flow ratio to the center parts of the watershed which represents the high potential of these parts to underground dam construction.

In many floods controlling, watershed-management and water-resources projects, estimating of river flow-rate is important and needs a comprehensive hydrological modeling of flow-rate evaluation. Need for enlightening the status of water-resources and precipitation in different watersheds and the lack of networks of hydro-meteorological gauging stations, reveal the importance of estimating the runoff volume in watersheds. In addition, designing of hydro-structures on rivers such as bridges and weirs are in need of forecasting related floods of the territory. In this research explores discovering of the hydrological soil groups of Ab-Bakhsha watershed in Bardisr in Kerman province for evaluating the flood peak and volume. There is soil group data just for one sub-basin therefore; the watershed suffers from lack of hydrological soil group data. For that reason, slope maps evaluate the hydrological soil group which shows the 87% accordance with the available data. To continue, the HEC - HMS software modeled eight flood events using estimated data and rainfall-runoff observation. Four target-functions calibrated the model for curve number and coefficient K in Muskingum method. In the end, to evaluating the calibrated model, four flood events by NOF and EF goodness of fit tests were simulated. According to the results, the RMSE method as the best target-function used for optimizations. In general based on the lack of information about the soil curve number and promising results of this model, one can knows this method as a proper method for calculating the flood volume in preliminary study plans.

A flow-duration curve (FDC) illustrates the relationship between the frequency and magnitude of daily, weekly and monthly stream flow. Applications of FDC are of interest for many hydrological problems related to hydropower generation, river and reservoir sedimentation, water quality assessment, water-use assessment, water allocation and habitat suitability. This study was carried out in 33 selected watersheds for regional analysis of FDC in Namak Lake basin. The FDCs were drawn for 33 selected watersheds, discharges of two to 92 percent were determined and the best probability distribution was recognized among ten probability distributions. The discharges of two to 92 percent with two-year return period were estimated. Using factor analysis selected six factors, includes area, average height, main channel length, drainage density, and percentage of permeable formations among 18 physiographical, meteorological, geological and land use characteristics as independent variables for regional of analysis of FDC. The multiple regression technique and combination of cluster analysis for determination of the homogenous watersheds and multiple regression techniques were carried out regional analysis of FDC. Determination coefficient (R2), root mean square error (RMSE) and efficiency coefficient (CE) statistics are employed to evaluate the performance of the models in all region and homogeneous regions. The results showed that regional analysis with homogeneous regions causes higher efficiency and lower error. According to beta coefficient of the regression equations, the continuity of the main channel flow rate was the most important parameter in the FDC.

Land use change is one of the most important factors of global environmental change. So, understanding and predicting the causes, processes and consequences of land use and land cover has become a major challenge. The Remote Sensing and Geographic Information System (GIS) technologies can be used effectively to detect and quantify of land use changes and its effects on the environment. The purpose of this study is to evaluate the land use changes in Abolabbas basin in the period of 1990-2009 using remote sensing and satellite images. At the first step, Land sat satellite images have been used for the preparation the land use maps of 1990 and 2009. Then, satellite images were classified using a artificial neural network algorithm with fine accuracy in eight class of land use (rain fed farms, irrigated farms, rainforest, semi-dense forest, thinning forest, fair rangelands, poor rangelands and residential areas). The results showed that area of rainforest and semi-dense forest decreased during this period 8.48 and 12.26%, respectively, and have become to the thinning forest and rangelands that increased 10.39 and 12.35%, respectively. On the other hand, agricultural area (rain fed farms, irrigated farms) decreased 1.79% and residential area increased 0.19%. With regard to the land cover has changed in this period, these changes can have negative effects on the environment and natural resources, also natural disasters such as floods will increase.

Topographic factor is an important factor of computer models of USLE family due to the high sensitivity of model results to its variation and complicated effects of topography on soil erosion. Moore and Wilson (1992) have introduced a well-known method to compute LS factor of RUSLE model using digital elevation model (DEM).The objective of this study was to determine the proper cell size of DEM for computing LS factor in a 7116 ha area, in Rashakan region at the southern part of Urmia. DEM models with cell sizes of 30, 50, 75,100, 200 and 400 m were prepared in ArcGIS 10 environment and the raster based maps of LS were derived from each DEM model based on Moore and Wilson method. Spatial dependence of the LS factor was analyzed and the proper cell size of DEM model was selected based on the degree of spatial dependence. Results showed that the spherical model explain the spatial pattern of LS factor and the DEM model with 75 m cell size has the strongest spatial dependence (0.523) and the highest coefficient of variation (0.983). As a result, in this region DEM with 75 m cell size is suggested as a proper cell size to compute LS factor based on Moore and Wilson method.