عنوان مقاله [English]
Climate change related issues increasingly received significant attentions in recent years due to its consequences in different viewpoints of economic, social and environment. In this regard, drawing guidance from vulnerability assessment as a process for characterization of watersheds against climatic components could provide strategic implications of climate change. Generally, vulnerability is considered as an ecosystem susceptibility state against to harm from exposure to stressors and from the lack of capability to adapt. Watersheds are greatly different in terms of their supporting values, exposure to climatic changes, and sensitivity. Therefore, understanding these differences could be helpful for the set priorities and selection of management attitudes. Depth understanding of climatic vulnerability changes in different environments is emphasized by the Intergovernmental Panel on Climate Change (IPCC). Not all parts of the specific watershed are equally vulnerable to climatic components. It is expected some parts are supported by more water resources, and some are inherently more sensitive to climate change. Moreover, ascertaining the magnitude of vulnerability in areas undergoing such changes is highly important for land managers and decision makers. The vulnerability assessments provide managerial recommendations to appropriately predict and respond to projected climate-hydrologic-land cover changes. Towards this important, the present study was planned as a case study to assess the climatic vulnerability of the Samian Watershed in Ardabil Province based on some important climatic and physiographic indices.
Materials and methods
The present study was conducted in the Samian Watershed (ca. 4235 sq. km) with 27 sub-watersheds located in central of Ardabil Province, Iran. The mean annual precipitation in the study watershed is about 312.25 mm, with temperature of 8.2 °C. A key component to implement a successful indicator-based approach is selecting the most reliable and suitable indicators for vulnerability assessment. Based on reviewing of the literature, to assess the climatic vulnerability of Samian Watershed, eight important indicators from climatic and physiographic aspects including dry and wet seasons, cold and warm periods, maximal wind speed, altitude above sea level and standardized precipitation index (SPI) were used. Thence, the Kolmogorov-Smirnov test was applied to determine the appropriate thresholds to distinguish the different classes of each used indicators. To determine the indicators related to rainfall, temperature and wind, the data of 16 stations which distributed through whole study watershed for the period of 1989–2014 were provided and analyzed. In addition, the digital elevation model (DEM) and Drought Indices Package (DIP) were applied for indicators of altitude above sea level and standardized precipitation index (SPI), respectively. In overall, all indicators was classified between one to five scales based on the vulnerability intensity. Thereafter, the overall vulnerability point (OVP) were obtained for whole study watershed. Totally, all study climatic and physiographic indicators as well as overall vulnerability point (OVP) were mapped and interpreted through sub-watersheds under consideration. The interpolations were made using the Inverse Distance Weighted (IDW) and Thiessen processes in the ArcGIS 10.6.
Results and discussion
The results showed that the mean vulnerability of Samian Watershed based on climatic variations of dry season, wet season, cold period, warm period, maximal wind speed, altitude above sea level and SPI index were 65.36 mm, 194.86 mm, 0.51 °C, 15.71 °C, 55.66 Km h-1, 1707 m and 0.0026. The standard deviation of these indicators in that respect were obtained 9.69, 34.02, 1.57, 0.83, 15.23, 304 and 0.0020. The dry season index in the Samian Watershed area was varied in the range of 48.05 (sub-watershed 21) to 86.63 (sub-watershed 12) mm and the wet season index was within the range of 254.99 (sub-watershed 16) to 130.83 (sub-watershed 3) mm. The cold season index also ranged between -5.87 (sub-watershed 8) to 2.07 (sub-watershed 3) °C and the warm season index fall in the range of 13.03 (sub-watershed 8) to 16.96 (sub-watershed 3) °C. Furthermore, the maximum wind speed index varied between the ranges of 34.20 (Sub-watershed 8) to 78.48 (sub-watershed 1) Km h-1, altitude above sea level was between 1326 (sub-watershed 21) to 2596 (sub-watershed 14) and SPI index within the range of 0.0006 (sub-watershed 16) up to 0.0111 (sub-watershed 8). In addition, the results showed that among 27 sub-watersheds, sub-watersheds 15, 16 and 17 were grouped in high class and the sub-watersheds 20, 21 and 24 were grouped in resilient class in terms of overall vulnerability point (OVP). Besides, the variation of spatial distribution in the climatic vulnerability was clearly observed for Samian Watershed. However, main parts of the watershed is distinguished vulnerable. This findings confirmed the dynamics of the used indicators in evaluation of Samian Watershed vulnerability. In addition, the results showed the road maps for policy managers to provide meaningful management solutions for each sub-watershed based on every study indicators. The results of the research, while highlighting the importance of the effects of climate change, are necessary for their application in applying appropriate management and adaptation to climate change in the future policies of the watershed management. Therefore, the results can be used more as inputs for developing a comprehensive and integrated framework for climate change mitigation and adaptation solutions. In addition, the results of this study could be used to reduce or control the climate change risks in the Samian Watershed area.
In the present research, the climatic vulnerability of Samian Watershed, Iran were assessed in terms of some significant climate and physical indicators. The results verified the spatial variations of vulnerability in terms of each study indicators and overall vulnerability through 27 sub-watersheds. This paper includes powerful tools and example of watershed-scale vulnerability assessments that could be a basis for jurisdictions around other places of Iran and the world. The results of the research, while highlighting the importance of the effects of climate change, are applicable to develop appropriate managerial and adaptation strategies in terms of climate change. Along with vulnerability increasing in different conditions, it is suggested to adjust and use more indicators with the addition of socioeconomic considerations and non-climatic factors. The findings also inform the associated organizations to give more attention to collect comprehensive data bank and facilitate equipping the watersheds for collecting high resolutions information related to vulnerability assessment in future studies.
Keywords: Climate change, Land degradation, Resilience, Watershed vulnerability