Spatial Pattern of the Multifunctional Disturbance Indicators in the Samian Watershed, Ardabil Province

The decrease in global biodiversity caused by human activities and the continuous expansion of man-made land use has deepened the need better to understand the relationship between biodiversity and human disturbance. By knowing and examining the process of disturbance changes over time, it is possible to identify the factors that cause it and make appropriate decisions to reduce disturbances. Meanwhile, the application of landscape ecology in various fields of urban planning shows the ability to analyze and quantitatively express the results of human-environment interaction. Gaining comprehensive knowledge of the behavior of this type of change is necessary to achieve systematic management and efforts to ensure the sustainability of ecosystems. In addition, identifying the main processes and structural factors in creating key changes in the landscape provides a proper understanding of the behavior and changeability of the landscape. Ecological disturbances can be caused naturally (fires, floods, avalanches, hurricanes, or volcanoes) or by human activities (road construction, pollution, land use, or mining) and can even completely change a habitat. One of the needs of planning for effective and sustainable management and protection is a better understanding and awareness of the process of spatial changes of this type of disturbance. The timely identification and monitoring of ecosystem responses to disturbance stimuli is an important step in ensuring the sustainable use of natural resources and integrated watershed management. Based on this, the current research aims to identify disturbance drivers, develop multifunctional disturbance indicators, and analyze their spatial patterns in the Samian Watershed located in Ardabil Province.

Materials and Methods  :

In the present study, according to the literature review of the watershed and research related to disturbance indicators, a total of 29 disturbance drivers were identified. Then, Spearman's test was used to identify and remove disturbance indicators with significant correlation (p-value<0.05). Finally, using the weighted sum of disturbance drivers, four multifunctional indices based on land use (DI-LU) (with criteria of agricultural area, range area, total agricultural and residential, dry farming area, irrigation area, urban area, urban 600 m buffer, urban-agricultural 600 m buffer, ndvi and road density), demographic (DI-DG) (with criteria of population density, rural household density, density of 10-year working people, density of people working in agriculture, density of people working in the industry, density of people working in services and residential density), sources of pollution (DI-CR) (with criteria of soil erosion, special sediment, LQ spatial coefficient in the agricultural, LQ spatial coefficient in the industry, river distance from residentional areas, density of mining operations, density of industrial centers, pol1utant density) and hydrology (DI-HR) with criteria (with criteria of slope, reservoirs and wetlands area, dam storage, dam density) and a total disturbance index (TDI) were developed.

In this research, the multi-functional indicators of disturbance in 27 Samian sub-watersheds were calculated and zoned based on identified disturbance drivers. The results of equal weighting showed that the variables used in the calculation of disturbance indices based on the first to fourth groups were assigned weights of 0.13, 0.50, 0.17, and 0.33, respectively. The results of zoning showed that the maximum value of disturbance index based on land use (DI-LU) related to sub-watershed 27 with a value of 0.77 in the high class, demographic (DI-DG) related to sub-watershed 27 with a value of 0.89 in the class very high, pollution sources (DI-CR) related to watershed 15 with a value of 0.61 were placed in the high category and hydrology (DI-HR) related to watershed 25 with a value of 0.82 were placed in the very high disturbance category. The average of the first to fourth multifunctional indices were 0.46±0.16, 0.40±0.16, 0.38±0.09, 0.52±0.15 and 0.44±0.08 respectively. The results of the total disturbance index showed that the mean and standard deviation of the total disturbance index (TDI) are equal to 0.44 and 0.08. This confusion index was categorized into three categories: low, medium, and high. Besides, a significant area of the entire Samian watershed was placed in the middle class (0.41-0.60).

In recent decades, natural ecosystems have experienced unprecedented negative disturbances due to global climate warming, extreme weather events, excessive human exploitation of resources, and damage to the environment. In the long run, this has led to a series of complex problems that will threaten the survival and sustainable development of society. Accordingly, the regional identification of disturbance drivers is very important to reducing the conflicts between socioeconomic development and environmental protection. In this context, according to the zoning results, most of the sub-watersheds were placed in the middle class based on the fourth group, which indicates the importance of considering factors such as slope, dam storage, and dam density. From the general point of view, the Samian watershed has a medium, low, low, and medium class, respectively, based on the disturbance indicators of the first to fourth groups. In general, the central and northern parts of the watershed have higher disturbances than other parts. The results of the spatial analysis also showed that the central parts of the Samian watershed are affected by more disturbance. The results of the present research are used in the diagnosis of the dynamics of disturbances to understand the interactions of a watershed system and develop the strategies required for sustainable management.