1- Yazd University
Abstract: (371 Views)
Introduction and Objective: According to the opinion of most specialists, the resources and health of the country's ecosystems are being destroyed. In this regard; In order to properly plan and manage, while preventing destruction and reducing the pressure on ecosystems, it is necessary to be aware of the health of watersheds. A healthy watershed is a watershed where natural vegetation has provided the necessary substrate for hydrological and terrestrial processes. In addition, healthy ecosystems are resistant to stress and pressure and provide high quality and quantity of services for the welfare of communities. so; Assessing the health of ecosystems is important not only in terms of preserving the environment, but is also important for the social and economic activities of communities. In this regard, the current research is planned with the aim of investigating the temporal changes of ecosystem health indicators using the VOR model in the Chehelkhaneh sub-watershed located in the Zayandeh Roud Watershed. Since the Zayandeh Roud Watershed is one of the most sensitive watersheds in the country and irreparable environmental damage have been caused to this watershed in the last two decades, selection of this watershed for the present study is justified.
Material and Methods: In order to investigate the change of the health indicators of Chehelkhaneh sub- watershed, the VOR (power-structure-resilience) model was used during a 10-year statistical period (2011-2021). In this method; V, O and R represent the production power (function), structure and resilience of ecosystems, respectively. This model is closely related to the issue of ecosystem stability, which indicates the watershed's ability to maintain its structure and function over time against external factors. Therefore; to carry out the present study, first, land use maps for 2010 and 2010 were selected from Landsat 5 and 8 satellite images and required pre-processing was done. Indeed; By using the correlation method between the bands, a false color combination was created, then each of the land use classes were separated from each other in separate stages using the supervised classification method. Next, after preparing the land use map of the study area, land cover maps (NDVI) related to the power indicator were estimated. This indicator shows the density of land cover in the region. In the next step, Fragstats software was used to extract structure (SPLIT and PD) and resilience (LPI and AI) indicators. In this regard; The indices of fragmentation (SPLIT), patch density (PD), largest patch (LPI) and aggregation (AI) were used. It should be noted that the Fragstats software is based on land use. In the following, after calculating all the mentioned indicators, standardization was done and the health of Chehelkhaneh sub- watershed was determined.
Results: Based on the results in 2011, rangeland (42.43%), irrigation and dry farming (30.84%), dry farming (250.30%), irrigation farming (1.14%), and rock (0.30%) respectively have the largest area assigned. In case in 2021; irrigation and dry farming (50.95%), , rangeland (39.80%) and rocky (9.26%) respectively have the largest area in the region. In other words, the land use of irrigation and dry farming is dominant in the region and the area of natural lands have also decreased, which indicates the destruction in the study area. In fact, large user units become small units and lead to the disintegration of the region. Also, the indicators values of power, structure and resilience were in 2011 as 0.69, 0.9, and 0.79 respectively and in 2021 as 0.47, 0.71, and 0.64 respectively. In this regard; The values of time changes of power indicators in 2011 and 2021 were 0.69 and 0.47 respectively, structure values were 0.9 and 0.71 respectively, and resilience values were 0.79 and 0.64. It should be mentioned; One of the main reasons for the decrease in the values of health indicators in the Chehelkhaneh sub- watershed is the lack of forest cover and the change of land use to low yield lands. This important, has led to a decrease in the quantity and quality of the region's ecosystems. Finally; based on the obtained indicators values, the health of Chehelkhaneh sub- watershed in 2011 and 2021 was 0.49 (Moderate) and 0.21 (Partly not healthy), respectively. In this regard, the structure indicator has the most impact on the health of Chehelkhaneh sub- watershed and resilience and power indicators have been assigned the next priorities. In other words, the results showed that the effect of the ecosystems health indicators is different and the health level of the studied region has decreased over time is progressing towards being unhealthy.
Conclusion: The present study is new in terms of the comparative investigation of the temporal changes of ecosystem health indicators using the new VOR model and in terms of the attention of managers and experts in the necessity to evaluate the health of ecosystems based on the results obtained. So; since the land use change in this region to due to the lack of water and the low production potential of the land, after several times of cultivation is abandoned and is cost-effective, carrying out protective operations in order to reduce the destruction of the region with the participation of local communities and holding educational-promotional courses in order to promote and raise the awareness of the communities is suggested. Also, to create institutions compatible with the watershed situation, while increasing intra- and extra-organizational cooperation in the direction the policy, laws, and environmental risks management of the projects. In general, it can be acknowledged that conducting the present research contributes significantly to the preparation of the health atlas of the country's ecosystems.
Material and Methods: In order to investigate the change of the health indicators of Chehelkhaneh sub- watershed, the VOR (power-structure-resilience) model was used during a 10-year statistical period (2011-2021). In this method; V, O and R represent the production power (function), structure and resilience of ecosystems, respectively. This model is closely related to the issue of ecosystem stability, which indicates the watershed's ability to maintain its structure and function over time against external factors. Therefore; to carry out the present study, first, land use maps for 2010 and 2010 were selected from Landsat 5 and 8 satellite images and required pre-processing was done. Indeed; By using the correlation method between the bands, a false color combination was created, then each of the land use classes were separated from each other in separate stages using the supervised classification method. Next, after preparing the land use map of the study area, land cover maps (NDVI) related to the power indicator were estimated. This indicator shows the density of land cover in the region. In the next step, Fragstats software was used to extract structure (SPLIT and PD) and resilience (LPI and AI) indicators. In this regard; The indices of fragmentation (SPLIT), patch density (PD), largest patch (LPI) and aggregation (AI) were used. It should be noted that the Fragstats software is based on land use. In the following, after calculating all the mentioned indicators, standardization was done and the health of Chehelkhaneh sub- watershed was determined.
Results: Based on the results in 2011, rangeland (42.43%), irrigation and dry farming (30.84%), dry farming (250.30%), irrigation farming (1.14%), and rock (0.30%) respectively have the largest area assigned. In case in 2021; irrigation and dry farming (50.95%), , rangeland (39.80%) and rocky (9.26%) respectively have the largest area in the region. In other words, the land use of irrigation and dry farming is dominant in the region and the area of natural lands have also decreased, which indicates the destruction in the study area. In fact, large user units become small units and lead to the disintegration of the region. Also, the indicators values of power, structure and resilience were in 2011 as 0.69, 0.9, and 0.79 respectively and in 2021 as 0.47, 0.71, and 0.64 respectively. In this regard; The values of time changes of power indicators in 2011 and 2021 were 0.69 and 0.47 respectively, structure values were 0.9 and 0.71 respectively, and resilience values were 0.79 and 0.64. It should be mentioned; One of the main reasons for the decrease in the values of health indicators in the Chehelkhaneh sub- watershed is the lack of forest cover and the change of land use to low yield lands. This important, has led to a decrease in the quantity and quality of the region's ecosystems. Finally; based on the obtained indicators values, the health of Chehelkhaneh sub- watershed in 2011 and 2021 was 0.49 (Moderate) and 0.21 (Partly not healthy), respectively. In this regard, the structure indicator has the most impact on the health of Chehelkhaneh sub- watershed and resilience and power indicators have been assigned the next priorities. In other words, the results showed that the effect of the ecosystems health indicators is different and the health level of the studied region has decreased over time is progressing towards being unhealthy.
Conclusion: The present study is new in terms of the comparative investigation of the temporal changes of ecosystem health indicators using the new VOR model and in terms of the attention of managers and experts in the necessity to evaluate the health of ecosystems based on the results obtained. So; since the land use change in this region to due to the lack of water and the low production potential of the land, after several times of cultivation is abandoned and is cost-effective, carrying out protective operations in order to reduce the destruction of the region with the participation of local communities and holding educational-promotional courses in order to promote and raise the awareness of the communities is suggested. Also, to create institutions compatible with the watershed situation, while increasing intra- and extra-organizational cooperation in the direction the policy, laws, and environmental risks management of the projects. In general, it can be acknowledged that conducting the present research contributes significantly to the preparation of the health atlas of the country's ecosystems.
Type of Study: Research |
Subject:
مديريت حوزه های آبخيز
Received: 2024/02/10 | Accepted: 2024/05/21
Received: 2024/02/10 | Accepted: 2024/05/21
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