Hydromorphology is a branch of physical geography which deals with the forms created by running water, especially rivers. The recognition and explanation of Hydromorphological factors and their action on the primary structural surface of Lileh Javaan Roud Drainage Basin and making applied maps are important for the recognition and implementation of environmental management of the Basin. The significant role of running water is shown in the investigation of geology, climatology, physiography, hydrology, soil, vegetation and analysis of influent factors in making forms and processes and the existing landforms in the Basin. The role of human being as an intensifying figure of erosion and development of new forms such as land slide and gully erosion is also important. The influential function of running water on the structure of Drainage Basin shows the important effect of the paleoclimate. The destruction of agricultural lands, the development of gullies, and the increasing destructive power of floods are some examples of the factors affecting the life of people in this area.

Introduction: Since flooding causes death and economic damages, then it is important and is one of the most complex and destructive natural disaster that endangers human lives and properties compared to any other natural disasters. This natural disaster almost hit most of countries and each country depending on its policy deals with it differently. Uneven intensity and temporal distribution of rainfall in various parts of Iran (which has arid and semiarid climate) causes flash floods and leads to too much economic damages. Detention Basins can be used as one of the measures of flood control and it detains, delays and postpones the flood flow. …

Regarding the importance of instantaneous peak discharge estimation for watershed management study, in this research make an effort to make link between constant parameters (geomorphologic) and variable (hydrologic) to present models with minimum dependence on climatic and hydrologic data in hydrologic estimation. So, with using of synthetic unit hydrograph at Drainage Basin of Kan (Soleghan River) and to compare these results with recorded peak discharge in outlet of watershed, the best model can be derived. So, comparison of study models from relative mean error (RME) and root of mean square error (RMSE) in study Drainage Basin located in central Alborz watershed shows RME for GIUH model is 17.99, RMSE is 15.46 for Snyder RME is 59.66, RMSE is 26.83, SCS and Triangular models have the best estimation, respectively. Regarding to lack of recorded instantaneous peak discharge in Kan Drainage Basin’s hydrometric station (11 events), we can’t drive instantaneous peak discharge model. For this reason, with using of factors in each of studied models, other effective factors and 82 recorded events of daily peak discharge, daily peak discharge model derived. So the purpose of this study is presentation regional model for peak discharge estimation. For this purpose from GIUH, Synyder, SCS and Triangular models factors and other effective factors used.

In this paper after introducing geographic features of Gamasiab Basin in the west of lran (Nahavand plain), some general characteristics of the Basin, as well as geologic, hydrologic and geomorphological characteristics are discussed.The geomorphic features of the region and processes are so varied that we can find a variety of features and phenomena produced by tectonic, fluvial, glacial, karstic , mass movement, and anthropogenic processes. All these make the region a unique place for studying many geologic, geomorphic and hydrologic physical landforms.The aim of the paper is investigating the suitability of the Basin for geomorphologic and hydrologic studies for B.S. and M.S. students in geomorphology and hydrology fields and emphasis on the need for further research for development plans in the region. Of course recognition of physical potentials of the region can lead to the development of ecotourism and scientific tourism in general.

Due to successes of fingerprinting method in producing rapid and low-cost information of sediment sources, in this research this method was used in three sub-cathments of Chasht-Khoran Basin in Semnan Province: Amrovan, Atari and Ali-Abad. Samples below 63 mm were separated and 15 fingerprinting propertis was measured. In the first stage comparison of means and differentiation analysis were used for determination of the characteristics that can differentiate sediment source as well as possible. In second stage, by minimizing composite multivariate model by optimization methods, the share of each source was determined. The results shown that, in Amrovan Catchment, For properties consisting of Co, Ph, Kaolinite and K were recognized as optimum composition of sediment tracers which could differentiate sediment source completely. In Atary Catchment, the optimum composition of tracers are Na, Co, XLF and kaolinite which differentiate source by %91.7. In Ali-Abad Catchment five parameters were recognized as optimum composite which are:Na, XLF, Ca, Co and smectit which completely differentiated sediment sources. The results of calculated composite multivariate model have shown that Upper Red formation in Amrovan, Atari and Ali-Abad Sub-Catchment has the highest share in sediment production. The sediment production in these three sub catchment are as follows:35.9, 23.53 and 86.64% respectively. Therefore sediment management and control strategies should be performed on these sources.

Today, due to climate change, natural hazards and how to deal with them are among the most important concerns of researchers in environmental planning and crisis management. The purpose of this study is the assessment of the potential flood risk in Sarbaz Drainage Basin. For this purpose, the databases including elevation, slope, geological characteristics, soil characteristics, precipitation, vegetation, land use, and vector layers of the main channel, streams and Drainage densities of the Basin were used. By using the questionnaire and experts' opinion as well as hierarchical analysis, the weight of influences of each layer was calculated in Basin flooding. Each of these layers was classified based on the flood potential from low to high-risk scale and eventually merged with the weighted overlay model in Geographic Information System. The results showed that main streams, land use, and precipitation are the most important components in the flood risk of the Sarbaz river Drainage Basin. From the total area of the Sarbaz Basin, only 0. 5% has a high to extremely high flood potential, and the central areas of the Basin have the highest potential for flood due to topography and special hydrographic conditions. In addition, the main river Basin districts towards the outlet of the Basin as well as parts of the margins of important sub-streams have the highest flood potential. Despite the limited area of the high-risk zone, due to population density and agricultural land, the importance of this area is very high in crisis management.

In this research Quaternary Deposits of Taleghan Drainage Basin were investigated, related map was provided and their erodibility was determined. The most widespread Quaternary Deposits of Taleghan Drainage are alluvial terraces which are as follows from the higher elevations to present alluvial river: ˝ Mindel˝ Terrace, ˝Riss˝ Terrace,˝ Wurm˝ Terrace ,˝ Toria War˝ Terrace . The erodibility of alluvial terraces and alluvial fan deposits were investigated by different methods. For this purpose, in the case of ˝ Riss˝ and ˝ Toria war˝ alluvial terraces having thin soil horizon, modified –K parameter in USLE model and rainfall simulator were used. For ˝ Mindel˝ and ˝ Wurm˝ Alluvial Terraces and Jazan– Varkesh Alluvial Fan having thick soil horizon, K parameter in USLE model and rainfall simulator were used. The results of this research have shown that the most widespread Quatenary Deposit of Taleghan Drainage is ˝ Riss˝ with 2743 hectars and 2.4% area. Alluvial Terraces are mainly found in the center of Drainage Basin. The amount of modified K parameter in ˝ Riss˝ Terrace is 0.12 and in ˝ Toria War˝ Terrace is 0.17. The amount of K in ˝ Wurm˝ Terrace is 0.23, in ˝ Mindel˝ Terrace is 0.16 and in Jazan–Varkesh Alluvial Fan is 0.05, the order of erodibility from the highest to the lowest is ˝ Wurm˝, ˝ Toria War˝, ˝ Mindel˝, ˝Riss˝ Alluvial Terraces and finally Jazan–Varkesh Alluvial Fan. The order of erodibility from the highest to the lowest according to rainfall simulator is: ˝ Toria War˝, ˝ Wurm˝, ˝ Riss˝ and ˝ Mindel˝ Alluvial Terraces and finally Jazan–Varkesh Alluvial Fan. In conclusion, except for very coarse–grained alluvial terraces in which there are difficulties in using rainfall simulator, the results from K parameter in USLE model and rainfall simulator are in accordance with each other.

The Deficiency of Precipitation for Growth of Living Organisms is one of the Permanent Characteristics of Arid Climates. However, the Unexpected Reduction of Precipitation or those Rainfalls Which are Less than Long-Term Range in an Area Which is not Completely Arid Creates Many Risks. This Phenomenon is Called Drought. In this Study the Data on Annual Precipitation for the Stations of Ardebil, Ahar, Pars Abad, Maku, Jolfa, Khoy, and Marand Were Used With the Purpose of Studying the Precipitation Conditions of Aras Drainage Basin, Applying Statistical Analysis and the Calculation of Wet and Dry Years. The Indexes Used in this Study Include Dependable Rainfall Index (DRI), Nitzche Technique, and the Percentage of Normal Precipitation Index (PNPI). Findings of the Adaptation of these Methods Led to the Determination of Precipitation Conditions, and the Stipulation of Frequencies of Dry and Wet Year occurrence in the Stations Under Study. The Results of this Study Indicate that in All Stations the Drought Phenomenon is Coincided With Intensities and Also Weaknesses and in Most Stations the Precipitation is in Normal Situation. Among the Methods Applied, the DRI Method Having Lesser Limitations and More Capabilities is Better than the Other Methods for Determining Dry and Wet Years.

Hydrologic drought can be studied in different ways. One of the common methods is the use of low flow indexes. In this study for the purpose of determine of the identity of aspects of low flow, the homogenous zones, the extraction of regional regression models, and finally, the study of low flow trends of Karkheh river Basin, applied the data of 13 hydrometric stations during the statistical period of 1960-2000. After qualitative and quantitative controlling and the retrieval of missing data used flow duration curves for indexes such as Q75, Q90 and Q95. Also frequency analysis of 10-day, and 20-day low flows was carried out for indexes such as Q10, 5, Q10, 50, Q10, 100, Q30, 5, Q30, 50, Q30, 100 and some more indexes. Afterwards, some other factors like physiographic, climatic, geologic and vegetation cover were applied as influential parameters in the regional analysis. These factors were used in cluster analysis and stepwise regression estimations. Final step was the trend analysis of times series of the indexes. Results indicate that among the indexes being calculated, Q10, 100 and Q95 had the minimum quantities, whose amounts reduced as the return periods increased. On the hand, the time spans of 1998-1999, 1999-2000, 2000-2001 have undergone severe and long droughts in most of the stations. The review of the spatial distribution of indexes show better conditions of the south-eastern parts of the study area compared to the northern and southern sections in terms of dryness. Results of cluster analysis divided the area into two distinct homogenous units (in 0. 01 significant level). In the area No. 1, the elevation factor, in the area No. 2, the Drainage density, and in general, the factors such as the mean of area and Drainage density have the highest effects. The Spearman statistic, and Mann-Kendall findings also indicate that the low flow in upper Basin have negative trend during the statistical period.

The estimation of the amounts of precipitation in Qara-sou Drainage Basin is based on the observational data of 21 precipitation gauging stations in the area of the study. The correlation of above named elements with the data derived from the regional geographic factors indicates that using the regional data one can construct ,the final seasonal.and annual precipitation models. The multiple correlation coefficients of 69 up to 82% in interpretation of regional geographical factors in estimating the annual and seasonal precipitation of Basin is a good sign of the importance of processing statistical data in climatic studies and the use of geo-climate data. In the present study by using the mean of annual and seasonal precipitation records of the Basin stations,.the relation of the geographical parameters including the geographIcal latItude and longItude, the height above sea level, the distance from the mountain and the sea is modeled by multiple variables correlations method and precipitation rate is estimated.