Mokarram, M.,
Saif, A.,
Sathyamoorthy, D. Arabian Journal of Geosciences (18667511)8(7)pp. 4921-4937
In this study, we investigate the use of morphometric parameters and fuzzy membership functions to perform landform classification for different case areas of Zagros Mountains from digital elevation models (DEMs). First, multiscale DEMs with scales of 5 to 45 cells are generated using the lifting scheme. The maximum curvature for the scale of five cells has the lowest standard deviation, and hence, is determined to be the characteristic scale. Data layers are produced from the DEM of this scale for slope, minimum and maximum curvatures, and plan and profile curvatures. The fuzzy membership rules for these data layers are used to determine the landform classes. Comparison of the results of landform classification using the fuzzy classification method and topographic position index (TPI) with the geology map of the study area show that the fuzzy classification method provides higher accuracy (81 %) as compared to TPI (42 %). This is because for the fuzzy classification method, sloping areas are separated into sloping and non-sloping areas, and the membership functions are defined to prevent landforms belonging to the sloping areas from being classified in the non-sloping areas and vice versa. © 2014, Saudi Society for Geosciences.
Quaternary International (10406182)353pp. 236-249
Morphometric analysis using DEM (with 10m spatial resolution) is performed on the main cirque-like features in the Zardkuh Mountain (central Zagros Mountain Range, IRAN) to study the evolution patterns of these features. For this purpose, the cirque like-features were delimitated manually and their headwall and floor boundaries were modified based on the slope map (10m spatial resolution) classified based on the definition of cirque. The power law functions were fitted to 58 longitudinal cross-sections of the cirque-like features and their parameters were analyzed. The analysis showed that high values of b coefficient have good correlation with the cirque-like features which their morphometric characteristics are generally coincide with the definitions of cirques and location of the small glaciers. All the cirque-like features were classified based on results of the power function model and comparison of longitudinal profiles of the cirque like-features with the Vilborg and Evans classification system. At least 9 cirques with the classical characteristics were distinguished in the altitudes above 3650ma.s.l. of Zardkuh Mountain (mean values of b coefficient (. b-) is equal to 2.1). In addition, 19 cirques were classified as "Well-defined" (10 cirques with b-≥2.0) and "Definite cirques" (9 cirques with b-≥1.7). The other cirque-like features (30 cirques with b-≥1.4) were considered as "Poor" and "Marginal" cirques. In addition, the morphometric parameters of 28 cirques (with most glacial characteristics) and their allometric behaviors were analyzed. The allometric coefficients of length and width are above 1.0 and for depth is significantly below 1.0 (or vertical development of the cirques increases slower than that of length and width) in accordance with similar research. © 2014 Elsevier Ltd and INQUA.
Mokarram, M.,
Saif, A.,
Sathyamoorthy, D. IOP Conference Series: Earth and Environmental Science (17551307)20(1)
The aim of this study is to classify alluvial fans formed by high-gradient braided streams and torrents that discharge into the Oshtorankook altitudes in the Lorestan province, Iran. The morphology of the fans and their watershed is quantitatively described through estimated morphometric parameters. For relationships between geomorphological features of the fans and their drainage basins, self-organizingmaps (SOM) were used. In SOM, according to both qualitative data and morphometric variables, the clustering tendency of alluvial fans was investigated using 15 alluvial fans parameters. The results of the analysis showed that several morphologically different fan types were recognizedbased on their geomorphological characteristics in the study area. A strong positive relationship was found between the drainage basin area and size of the fan with a simple power function. In addition, the relationship between fan slope and drainage area was found to be negative and moderately strong with a simple power function. © Published under licence by IOP Publishing Ltd.
Carbonates and Evaporites (08912556)29(1)pp. 107-126
This study has been carried out with the aim of mapping karst and evaluation of degree of karstification of carbonate rocks in Iran. Mapping of karstic regions of Iran has been performed by some authors previously, but scale and limited information availability have limited the accuracy of their works. In addition, rock type was considered as the main factor to make a karstification map, and other important factors such as tectonic and climate conditions were ignored. One objective of this paper is a spatial evaluation of karst development in Iran considering the role of the chief factors affecting karst development. In this study, a theoretical karst map was developed on the basis of what is considered to be a proper combination of these factors. The main considered factors are those classified by White (Geomorphology and Hydrology of Karst Terrains, Oxford University Press, Oxford 1988) into three driving forces (i.e., chemical driving force, physical driving force and hydrogeological setting). Precipitation, temperature, relief, rock type, tectonic setting and stratigraphic thickness of soluble carbonate rocks are the main factors classified to describe the mentioned driving forces. In this study, precipitation and temperature are represented by the chemical weathering conditions during the modern and glacial periods prepared on the basis of Peltier's graphs. The required data were gathered from the updated maps with proper scale and detailed references. Then the data were mapped, classified, weighted and managed in separate layers in GIS environment. The karst index (K i ) is introduced to define the modeled degree of karstification computed by proper combination of six weighted layers, and the final theoretical karst map of Iran is prepared based on the ranked karst index. According to the combination method, values of K i could be in a range 0-400 in which higher values show more degree of karst development. The classified theoretical karst map shows that out of 205,589 km2 of carbonate units (12.62 % of the surface area of Iran) about 78,253 km2 (38.1 % of carbonate rocks) have very low to low degree of development of karstic features. About 98,145 km2 (47.7 % of carbonate rocks) have moderate degree and about 29,192 km2 (14.2 % of carbonate rocks) have high to very high degree of karstification. In other words, 7.81 % of Iran (62 % of the carbonate units) is underlain by carbonate rocks with moderate to high degree of karstification. Densities of caves and karstic springs are hydrogeological features used to check the calculated degree of karstification. For this purpose, complete inventories of caves and karstic springs in Iran were made. Out of 590 caves, 491 caves are located in carbonate rocks. From 1,074 karstic springs (with discharge above 10 l/s), 338 springs have discharges above 50 l/s; 146 caves and 330 springs (with discharges above 10 l/s) occur in rocks in areas of very low to low degree of karstification. About 243 caves and 430 springs fall in the moderate class and 102 caves and 314 springs in areas with high to very high degree of karstification. Cave densities (number of caves per area) are 0.0017, 0.0019, 0.0025, 0.0031 and 0.0046 caves per square kilometer for very low, low, moderate, high and very high classes, respectively. In addition, densities of springs are 0.0041, 0.0043, 0.0044, 0.0103 and 0.0122 springs per square kilometer for very low, low, moderate, high and very high classes, respectively. In other words, densities of caves and springs show a good correlation with the evaluated karstification. Final result is also checked by surface karstic landforms (such as karren and doline) on some examples of well-known karstic regions. © 2014 Springer-Verlag Berlin Heidelberg.
Deserts exist on every continent of the globe and cover more than 30% of the Earth's land surface. Although they typically do not have a large number of inhabitants, they are often the loci of economic and cultural activity. For example, the oil-producing nations of the Middle East are all found within a single arid region. At the same time, deserts tend to be fragile ecosystems, requiring little in the way of perturbations in order to cause tremendous changes in the landscape. The size, remoteness, and harsh nature of many of the world's deserts make it difficult and expensive to map or monitor these landscapes or to determine the effect of land use on them. Remote sensing is potentially a time- and cost effective way to fulfill these goals. In this research, we will discuss the uses and limitations of remote sensing in the world's deserts. The discussion will center on using remote sensing to detect and monitor landscape change and degradation in arid regions. Because vegetation is often linked to both the causes and consequences of arid land degradation, our discussion will further focus on the retrieval of vegetation parameters. In this paper, examples of successful applications of remote sensing to arid regions are given. Also, limitations and important considerations of remote sensing in arid regions are discussed. Ultimately, atmospheric remote sensing as it relates to land degradation in arid regions is discussed. And, a case study is presented in which various methods for estimation of vegetation cover are presented and compared.
