Alometry of Barchans morphometric parameters in the Southeast of Haj Ali Gholi playa

Managemental principles predominated on the development and evolution stages of the geomorphic landscapes are different، because landscape evolution، its relationship with other system components and its response to environmental changes and feedback is varied. One of the most important methods of management of geomorphic landscape are the study and evaluation of morphometric parameters and determining alometry between them. Alometry is the investigation of relative changes between system components، and represent the development of a system component compared with development of entire system or other components، also. Therefore، the study and evaluation of barchan morphometric parameters and alometry between them will help to managers and environmental planners achieve the unified and accurate recognition from landscape، on the one hand، it may be effective in the determination of stability، equilibrium and threshold of barchan system. One of the most important problems of management in arid and semi-arid regions is the identification and application of environmental principles governing on the behavior of Barchan dunes. Barchans are one of the windy depositional features that are forming in regions with medium sand and same direction of privalling wind. The aims of this study are the determination of the most important morphometric parameters of Barchan dunes in the southeast of Haj Ali Gholi playa and the recognition of relationships type، the ratio and alometry between them، in order to identify management principles governing on Barchan dunes. The study area in the research is barchan field that is located in the southeast of Haj Ali Gholi Playa. The area with extent about 25260 hectares، is one of the most important ergs of Haj Ali Gholi playa that is located irregularly along northeastern - southwestern edge of playa with 10 to 12 km length. This region is located at Eastern longitudes between 55° and 55°، 10΄ and at Northern latitudes between 35°، 45΄ and 35°، 50΄. At first، studied area is recognized via topography maps and Google Earth images. Then barchans morphometric parameters are measured along 10 transects that were covering entire extent of the erg. Measurements are based on figure (2). This figure shows types of barchan morphometric parameters and method of their measurement. We define for each barchan dunes، the lengths La، Lb and the widths Wa، Wb independently. Furthermore، this study introduces the length of the slip face Ls and the length Lo from the dune’s toe on the windward side to the brink. Finally، the height of the slip face H is defined at the highest point of the brink، which is the intersection of the brink and the longitudinal centerline of the dune. The total width (W) of a barchan is the sum of the widths Wa & Wb. The overall length (L) of a barchan is the sum of the length (Lo) from the windward foot of the dune to its crest، the length of the slip face (Ls)، and the average of the horn lengths [(La + Lb) / 2]. Then from measurement and determination of morphometric parameters، for recognition of type and intensity of relationships between them، we have been reexamined these relationships using SPSS software and regression analysis technique. Finally، with analysis and evaluation of the obtained relation using mathematical tests، the ratio and the alometry of morphometric parameters of studied Barchans have been defined and determined. Findings and In the study area، several barchans can be observed that they have the same form and shape generally. The barchan dunes of the southeast Haj Ali Goli playa have heights between 1. 2 and 17. 9 m، lengths between 19. 5 and 307. 9 m، and widths between 6. 3 and 165. 6 m، mainly (Table 1). The results obtained from statistical modeling by the regression analysis are presented in tables (2) and (3). Models Summary is described in Table (2)، in which the correlation index، determination index، adjusted determination index and standard deviation of estimation error are reported. Also، the values of model parameters (coefficient and line slope)، t value and their significant level are demonstrated in table (3). Totally In this study، the most important and the most suitable of relationships are following from simple linear relationships. So، in the results part، only، these relationships are presented (figure 3). Comparative evaluation of similar studies results reveals the achievement to different equations in other regions. As، quantitative researches of the morphology studied by other researchers، show the specific relationship between barchan morphometric parameters in their study area. Table (4) presents the results of this study as compared with others. As mentioned previously، Alometry is the investigation of relative changes among system components، and represent the development of a system component compared with development of entire system or other components، also. In the study، to determine the ratio between morphometric parameters of the studied barchan and identification of alometry between them، first was attempt to determine the types of their relationship، and then conclude the ratio from them. The obtained results are illustrated in the table (5). Discussion and The results show that the obtained relationships from relation assessment between morphometric parameters of studied Barchan represent a maximum significant linear relationship of Barchan length and height، with determination index 0. 945 and standard error of estimate 0. 889. Also، the obtained relationships from relation assessment and alometry among Barchan morphometric parameters are statistical and mathematical models reported in this study. The mentioned models provide the possiblity of rapid and accurate calculation of Barchan morphometric parameters، and illustrate the alometry among them. The recognition of morphometric parameters of barchan dunes and their alometry can act as an index in order to determine the condition of barchan system and also shed light on the thier trends. Furthermore recognition and estimate of these indexes is a consequence from rate of threat and distribution and provide for environmental managers with the same، that their investigation determines different region from the view point of environmental management and prioritize them.