Mahin Kalehhouei; Raoof Mostafazadeh; Abazar Esmali Ouri; Rahmani Naneh Karan, Fardin; Fazeli, Alireza; Nazila Alaei; Zeinab Hazbavi
Abstract
Introduction
The rainfall system of a major part of Iran is mediterranean, where the precipitation amount during the vegetation period is low. In addition, the occurrence of precipitation in the non-vegetation period or beginning of the vegetation period, which does not cover the surface of the earth ...
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Introduction
The rainfall system of a major part of Iran is mediterranean, where the precipitation amount during the vegetation period is low. In addition, the occurrence of precipitation in the non-vegetation period or beginning of the vegetation period, which does not cover the surface of the earth well, is one of the important reasons for water erosion in Iran. Since vegetation has a special role in soil erosion control and runoff retention, any change in the vegetation structure and pattern, which expresses the landscape pattern and function, can have a significant effect on changing hydrological processes. Therefore, the assessment of soil and water loss and the quantification of its relationship with landscape metrics provide key information for the development of water and soil quality management strategies.
Materials and methods
The current research was conducted to investigate the hydrological component changes with landscape metrics on 2 m2 plots using simulated rainfall at an intensity of 32 mm.h-1 in a part of rangelands of Ardabil County. At first, considering the type and percentage of vegetation as the main variable, eight groups of vegetation composition along with one group without vegetation (control) were considered with three replications. The composition (and percentage) of the vegetation from the first to the eighth groups, respectively, include low-height graminea predominance (45), the composition of dense bushes with graminea (43), bushes with low-height and medium-distribution (37), sparse bushes mostly with low and medium height (31), the composition of sparse bushes with graminea (56), dense bushes in upper parts (54), low-height bushes with very low distribution (15), and dense bushes with almost uniform distribution (56). After measuring the runoff and sediment at the plot outlets, different hydrological components were calculated. Then, plots with nine different vegetation combinations were imaged in three replicates before and after rainfall simulation. After transferring the images prepared from the plots to the Arc/Map10.8 environment, nine important landscape metrics were calculated.
Results and discussion
Changes in the mean patch density (4.43-26.90), largest patch index (54.16-86.75), edge density (17.12-107.38), landscape shape index (1.50-4.47), mean shape area (4.16-37.46), mean Euclidean nearest neighbor distance (0.00-1.65), landscape division index (0.19-2.31), mean patch shape index (1.24-22.85), and the effective mesh size (15.80-43.96) indicate their different influence from different percentage and composition of vegetation cover. Spearman's correlation matrix analysis showed a nonsignificant relationship between the mean soil loss, runoff volume, runoff coefficient, and sediment concentration with landscape metrics (r<0.26 and p-value>0.10). The small scale of the studied plots, the lack of diversity in the vegetation composition, and the uniformity in terms of vegetation height can be cited as the reasons for the lack of correlation. In general, groups with vegetation values above 50% had a better condition in terms of LPI, AREA_MN, and MESH, which indicates more connectivity and less degradation. The increase in vegetation cover and spatial heterogeneity above the landscape surface can change the path of sediment transport, reduce sediment connectivity, and lead to a decrease in sedimentation.
Conclusion
The obtained results are applicable in explaining the appropriate reference to optimize water and soil protection measures on the watershed scale. However, It is suggested that similar and more comprehensive research be done in different scales of erosion plots and even in the landscape (slope) scale so that by considering a wide range of vegetation, topography, climatic conditions, as well as successive rains, it is possible to compare the results, optimum selection of study scale, and finally planning to manage and protect vegetation and water and soil resources.
Khosrw Shahbazi; yahya parvizi; Mahin Kalehhouei
Abstract
Gully erosion contributes severe land degradation. It is therefore, necessary to identify the aggravating factors and to provide for sensitive areas to gully development. The aim of this study was to determine the spatial and climatic distribution of gully in Kermanshah Province, Iran and to identify ...
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Gully erosion contributes severe land degradation. It is therefore, necessary to identify the aggravating factors and to provide for sensitive areas to gully development. The aim of this study was to determine the spatial and climatic distribution of gully in Kermanshah Province, Iran and to identify the morphological characteristics and the main factors of their development. First, using 1: 20,000 and 1: 50,000 aerial photographs, the predominantly gully areas of the province were identified and then this information was corrected using field suevey. The climatic zones of the gully areas are identified using existing maps and modified by the Domarten Method. In each climate, one to three gully areas were identified as targets and in each of them a gully was identified and two replications were identified. The gully chanel chrectreristices were location, landuse, dimensions at the head-cut, intervals of 25, 50 and 75%, slope, width, length and cross section. The results showed that 17% of areas in the Kermanshah Province was affecterd by gully erosion comprising eight sub-climate classes. Dominat topographic conditions of gullies were developed at hilly and gentle plain areas with Trapezoidal cross section. The cross section indicated deep and V-shaped gully in marl formations (Fars group). These areas included Sarfiroozabad, Somar and Jabbarabad where most of gully measures were deeper and wider than other parts. Among the effective factors in creating and expanding the gully, we can mention heavy rainfall, slope, soil erodibility and destruction of vegetation upstream of the basin as natural factors and change of land use and improper exploitation as human factors in developing gully erosion.
Mohammad Rasoul Rajabi; Ali Nasiri Khiavi; Mahin Kalehhouei; Sonia Mehri; Azam Mumzaei; Khadijeh Haji; Abdulvahed Khaledi Darvishan
Abstract
The present research aimed at presenting a new SWOT strategy for integrated watershed management of Asiabrood in Mazandaran Province. At first, the SWOT matrix and the tables identifying the strategic indicators of internal and external factors were formed and then internal and external evaluation matrices ...
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The present research aimed at presenting a new SWOT strategy for integrated watershed management of Asiabrood in Mazandaran Province. At first, the SWOT matrix and the tables identifying the strategic indicators of internal and external factors were formed and then internal and external evaluation matrices were analyzed. A new strategy used in the discussion of the weighting of SWOT strategies was based on the fact that the final value of each strategy was multiplied by the number of effective strengths and opportunities and the final results were analyzed based on these priorities. Based on analysis of strengths and weaknesses, nine strengths and eight weaknesses were identified. The suitable water quantity and quality with a weight of 0.444, low air temperature with a weight of 0.395, mineral water utilization with a weight of 0.288 and economic poverty with a weight of 0.493, respectively, were the most important strengths, weaknesses, opportunities and threats. According to the internal-external factors evaluation matrix in the SWOT model, the strategy of increasing the sense of satisfaction of residents, based on the conventional method and the new strategy, gave the highest value. With a careful look, it can be concluded that strengthening the sense of satisfaction between residents happens when People problems in different sectors of livelihoods, including economic, social and cultural, have been considered more and, by presenting correct programs, have increased satisfaction and reduced migration to urban areas. In general, it can be concluded that due to the problems and solutions presented in this study, proper and applied planning should be used to compensate for the weaknesses and to strengthen the strengths as much as possible in the development of Asiabrood watershed.
