جستجوی مقالات مرتبط با کلیدواژه « سنگ شناسی » در نشریات گروه « آب و خاک »

Today, water erosion is considered one of the most important forms of nature destruction, and the problems caused by it are inseparable problems of the country's watersheds. Among the numerous environmental factors affecting soil erodibility, lithology, topography and climate factors are the most important factors affecting soil erodibility. The purpose of this research is to investigate soil properties including number of drops impact (NDI), mean weight diameter of soil aggregates (MWD), soil penetration resistance (PR), soil cohesion (COH), saturated conductivity (Ks) and soil erodibility index (K). Therefore, six rock types (granite, limestone, ophiolite, shale, marl and sandstone) were selected in Razavi Khorasan province and sampling was done in three slope classes 0-10, 10-25 and more than 25% in 2021. In order to compare soil erodibility in similar rocks in different climates, limestone was selected in Tabas city (dry climate). The results showed that the average soil erodibility index and other indices have a significant difference (P<0.001). The results of measuring soil erodibility index in different slopes showed no significant erodibility index in three slope classes (sig=0.893, p<0.05). The comparison of the average soil erodibility in different climates in rocks similar to Paleogene limestone with a value of 0.83 in Tabas limestone and 0.96 (ton ha h / ha MJ mm) sarakhs limestone showed that the average soil erodibility in different climate has a significant difference (sig=0.023, p<0.05). The results of measuring CSEI index showed that the highest amount of reduction in erodibility reflected by this index is in granite with a value of 64% and the lowest value in shale with a value of 25%.

The flow duration curve (FDC) is one of the most important and widely used signatures of catchment runoff response. It has been used in numerous hydrological applications as a part of planning activities related to agriculture, industry, urban water supply, navigation, flood control, reservoir and sedimentation studies, in-stream flow assessment, water quality management, and impacts of land use changes. The FDC is a graph of river discharge plotted against exceedance frequency and is normally derived from the complete time series of recorded river flows. Representation of the relationship between the frequency and magnitude of stream flows, making it a compact signature of a catchment’s functioning; it can be used to diagnose the rainfall-runoff responses in gauged catchments at a holistic functional level, as well as to regionalize them to ungauged catchments. For these reasons, in the past few decades, considerable effort has been expended towards detailed studies of FDCs, especially in the context of predictions in ungauged basins (Smakhtin, 1998, 2001, Castellarina, 2004, Niadas, 2005, Santhi, 2008. Li, 2010). However, most recent studies on the FDCs have been empirically based, which generally fall into two categories: graphical and statistical. The graphical approach focuses on exploring the controls of catchment climatic and physiographic characteristics on the shape of the FDC (Smakhtin et al), while the statistical approach employs statistical distributions to fit the FDC and then relates the parameters of the distribution to the catchment’s physical characteristics (Castellarin et al., 2004; Li et al., 2010). Several studies have been conducted on the impact of geometric and hydrologic parameters on the FDC. (Booker and Snelder, 2012. Brown, 2013). In unregulated streams, the shape of FDC is controlled chiefly by the geology of the basin and research on the effects of lithology on FDC in a certain area, leading to obtaining information for use in water resources management (Bloomfield, 2009).
Although both graphical and statistical methods demonstrated that different climatic and landscape characteristics impact the shape of the FDCs in different regions of the world (Li et al., 2010), it has been difficult to generalize the results from one region to another.
The aim of this research was to determine the factors affecting the flow duration curve with emphasis on the role of lithology in the estimation of flow duration indices.
The study area comprises 18 basins with areas from 69.1 to 3941 km2 which are located in the North part of Iran and is underlain mostly by rocks belonging to the hard formations. Carbonate formations in this area are appropriate distribution and cover about 28% of the studied area. Mean annual rainfall varies from 427 to 1131 mm/ year. Median slopes vary from 2.85 to 15.9%.
In this research, using data from the daily flow of rivers, flow duration curve indices, in eighteen hydrometric stations of the Caspian Basin were determined. Physiographic parameters extracted from the GIS environment and the various factors of climate, geology and land use were also calculated. Lithological units using digital geological map, with a scale of 1: 250,000 and based on expert opinions were divided into 4 classes and the area covered by each unit was calculated. Land use map based on satellite images with the division of forest, pasture, agriculture, surface water resources, and rock outcrops were prepared. Factor analysis and cluster analysis were conducted and the regression equations were derived. The accuracy of models using the coefficient of determination and standard errors were investigated. Finally, the most appropriate models in 1% and 5%, significant of levels extracted.
Factor analysis of 21 variables showed, six factors were chosen as the most important independent factors. In the multivariate regressions between agents of geologic formations, particularly carbonate hard formation and alluvial and between morphometric parameters, slope, and main river length and from land use classes, agricultural land use was determined as the best predictor of duration curve indices. Also, according to the power and exponential models, annual precipitation as the most important factors between climatologically factors was diagnosed. The validation results showed that the distributions of errors in all models were normalized and Durbin-Watson index was varied between 1.5 to 2.5.According to regional relations obtained, the contribution of hard carbonate formations along with Quaternary deposits, indicating their role in ensuring the continuity of the region's rivers.

Geologic and pedologic controls are the main factors determining the distribution of elements in natural soil environments. In order to assess the role of these factors in the content and distribution of major elements of soil, six parent materials including phyllite (Ph), tonalite (To), periditite (Pe), dolerite (Do), shale (Sh) and limestone (Li) were selected in Fuman-Masule region. Soil genesis and development of representive residual pedons were studied for each parent material. Total content of Si, Al, Ca, Mg, Fe, Mn, K, Na, Ti and P of soil horizons were measured and compared to the geochemical and mineralogical composition of parent materials. Maximum concentrations of Fe2O3 and MgO were found in the soils derived from Pe and Do; however, these soils had low content of SiO2 and Al2O3, which is in conformity with the geochemical composition of the parent rocks. On the contrary, FeCBD content of these soils was lowest, indicating the low degree of soil development and, by the same fact, the importance of inheritance factor in soil Fe concentration. However, comparison of total Fe and FeCBD in Li1, Sh2 and To2 revealed that relative development of these pedons is higher than the others. Silicon depletion in Ph1, To2 and Sh2 pedons, relative to parent rocks, is higher than in Pe and Do pedons. However, this element is enriched in Li pedons. MnO content of Pe and Do pedons is governed by geogenic factors, while in Sh pedons, pedogenic factors, especially redox conditions, play the major role. Exchangeable forms of Ca and Na are determined by soil properties rather than by parent material type. Notwithstanding the redistribution of all major elements throughout pedons due to soil forming processes, the importance of inheritance factor in soil Si, Al, Mg, Fe, K, and Ti is higher than pedogenic factors.

Geologic and pedologic controls are the main factors determining the behavior of elements in natural soil environments. In order to assess the role of these factors on content and distribution of selected major and trace elements in soil, six parent materials including: phyllite, tonalite, periditite, dolerite, shale and limestone were selected in Fuman-Masule region. Soil genesis and development of representive residual pedons were studied for each parent material and the total content of Si, Al, Ca, Mg, Fe, Ti, Mn, Ni, Co, Cr, Cu, Pb, V and Zn were compared among them. Enrichment/depletion patters of trace elements were assessed using Ti as reference element. Generally, Cr, Ni, Co and V are highest in soils derived from peridotite (984, 285, 53 and 204 mg/kg, respectively) and dolerite (1023, 176, 39 and 185 mg/kg, respectively). In the same way, Si and Al exhibit the features of parent materials in the sense that the lowest content was observed in soils developed on peridotite, dolerite and limestone. Zinc and Pb are highest in soils derived from shale (106 and 27 mg/kg, respectively). In a given pedon, different elements exhibited different enrichment/depletion patterns; moreover, a given element may behave differently not only in soils with different parent materials but also, in some cases, in soils developed on similar lithology. Lead, Zn, Cu and Mn have been generally enriched in most pedons, except in some acidic and strongly leached soils, whereas Co, Cr, Fe, Ni and V have been leached, especially from Dystrudepts and Eutrudepts. The latter elements, however, showed enrichment trend in Hapludalfs and Argiudolls parallel to the development of illuvial B horizons.