Document Type : Research Paper
Authors
1 Assistant Professor, Department of Soil Science and Engineering, Faculty of Agriculture, University of Maragheh, Maragheh, Iran
2 PhD graduate of Watershed Science and Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
3 Assistant Professor, Soil Conservation and Watershed Management Research Institute (SCWMRI), Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
Abstract
Introduction
Watersheds, as key units of water resources management, play a fundamental role in supporting ecological processes, regulating the hydrological cycle, providing water, conserving soil, and sustaining the livelihoods of human communities. These natural systems are exposed to increasing pressures from climate change, population growth, unsustainable exploitation, agricultural and industrial development, and land use changes. In such circumstances, the concept of watershed sustainability as the system's capacity to maintain optimal performance of ecological processes and environmental services in the long term has gained special importance. In addition to providing early warnings of environmental degradation, assessing the health and sustainability of watersheds can also identify the causes of existing problems. The Watershed Sustainability Index is one of the valid indicators that quantify the status of watershed sustainability. This index, due to its high flexibility and usability at different scales, is known as a suitable tool for planning and decision-making in sustainable watershed management. Therefore, the present study was conducted with the aim of assessing the sustainability of the Atrak River watershed and providing a comprehensive picture of its functional status and ecological sustainability. The strengths of the article include the breadth and comprehensiveness of the indicators used (four key dimensions of sustainability), the 10-year study period, which increases the validity of the results, and the spatial assessment of watersheds and prioritization of actions, which allows for targeted policymaking.
Materials and methods
The Atrak River watershed with an area of 819,000 hectares is located in Golestan Province. The watershed sustainability index, developed by developing the UNESCO-HELP model and using the PSR (pressure-state-response) causal model, is one of the few indicators designed specifically for watersheds, which evaluates the sustainability of the watershed in question numerically and using a formula in the form of four sub-indices of hydrology (qualitative and quantitative), environment, life (livelihood conditions and human development), and policy. In this method, taking into account the available information and data (10-year period), the values of the parameters in the three components of pressure, status, and response were collected to examine each of the sub-indices and converted into quantitative form in the scoring range from zero to one and in five categories (0, 0.25, 0.5, 0.75, 1). The indicators receive a score of one in the best condition and a score of zero in the worst condition. The final WSI value was classified into three categories of low, medium, and high through the arithmetic mean of the sub-indices.
Results and discussion
The results of the hydrology section showed that in all sub-watersheds, per capita available water decreased during the 10-year study period. Also, the three sub-watersheds of Chat, Dashli Borun, and Gomishan are in the weak category in terms of the pressure component, and only Maraveh Tapeh is in the medium category. This condition is also true for the status and response component. According to the results, the TDS level has increased in all sub-watersheds. The results indicate a critical situation in the water quality sector of the watershed. In general, the average results of the hydrological index varied between zero and 0.25. The environmental index showed that the trend of increasing agricultural land is visible in all four sub-watersheds. The highest increase in agricultural land occurred in the Chat sub-watershed and the lowest in the Gomishan sub-watershed. Also, the highest increase in population occurred in the Chat sub-watershed, which confirms the results of the increase in agricultural land. The results indicate a very bad situation of the EPI index in the two sub-watersheds of Maraveh Tapeh and Chat, and Dashli Borun is in the next rank, and the Gomishan sub-watershed has the best situation in this index. According to the final score results, the situation of Gomishan is better than other sub-watersheds in the environmental sector. In general, the average results of the environmental index varied between 0.33 and 0.5. The results of the life index showed that the status of this index in all sub-watersheds was average to high. In general, the average life index results varied between 0.75 and 0.83. The results of the Policy Index showed that based on the average scores, the status of this index in all sub-watersheds was poor. In general, the average Policy Index results for all sub-watersheds were 0.58. The final values of the WSI index showed that all sub-watersheds have a poor status in terms of sustainability in all four main indicators. According to the average scores (0.448), the Atrak watershed is in the low category in terms of sustainability.
Conclusions
Considering the results obtained and the low level of sustainability of the Atrak River watershed, it is necessary to take immediate and planned measures to improve the sustainability status. The most important management and applicable suggestions in the watershed include the following. Integrated water resources management, which will increase the efficiency of water use in the agricultural sector by using modern irrigation methods and consumption management in the drinking and industrial sectors. Improving the quality of water resources, including controlling and reducing the input of pollutants into surface and groundwater sources, can be done through the development of urban and rural wastewater treatment systems. Protecting and restoring natural vegetation by implementing projects to restore degraded rangelands and developing protected areas, which play a fundamental role in improving the sustainability status of the watershed. Strengthening environmental governance and policymaking and establishing coordination between organizations responsible for water, agriculture, and the environment to implement integrated watershed management are other important strategies for improving the sustainability of the Atrak watershed.
Keywords
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