RESUMO
The Tarim River Basin (TRB) is an extremely arid area in China, suffering from dry climate and intense human activities, which have brought about significant changes in ecological processes and then, led to serious ecological vulnerability (EV). This study proposes an assessment framework to evaluate EV and analyze its dynamic change in the TRB during 2005-2015. An integrated method is developed with the Fuzzy Analytic Hierarchy Process (FAHP) and the Pressure-State-Response (PSR) framework, which highlights impacts of nature and anthropogenic interference on the ecology. Specific management strategies are put forward based on the spatial recognition of ecologically vulnerable areas in the TRB. The EV is divided into four vulnerability levels including Light I, Medium II, Heavy III and Very heavy IV. Results show that the average EV is at Heavy III vulnerability level in the TRB in the last 2005-2015, and there has been an increasing trend in EV, which even has come up to the Very heavy IV vulnerability level in the year 2013-2015. As a whole, the EV displays a high-to-low gradient from east to west during the study period. Heavy III and Very heavy IV vulnerability levels, distributed in the East, mainly in the mainstream areas with characterization of frequent human interferences, tend to increase persistently. In contrast, Light I vulnerability level, mainly in the west source areas, shows a significant decline after 2010. Based on the results, some suggestions targeted at different vulnerable areas were proposed to help restore ecological environments by integrating legal managements with public efforts. The proposed methodology, reflecting the nature and human interaction on the EV is of practical use for the ecological restorations in the TRB.
Assuntos
Conservação dos Recursos Naturais/métodos , Rios , China , Análise Espaço-TemporalRESUMO
Understanding contributions of climate change and human activities to changes in streamflow is important for sustainable management of water resources in an arid area. This study presents quantitative analysis of climatic and anthropogenic factors to streamflow alteration in the Tarim River Basin (TRB) using the double mass curve method (DMC) and the Budyko methods. The time series (1960~2015) are divided into three periods: the prior impacted period (1960~1972) and the two post impacted periods, 1973~1986 and 1987~2015 with trend analysis. Our results suggest that human activities played a dominant role in deduction in the streamflow in TRB with contribution of 144.6% to 120.68% during the post impacted period I and 228.68% to 140.38% during the post impacted period II. Climatic variables accounted for 20.68%~44.6% of the decrease during the post impacted period I and 40.38% ~128.68% during the post impacted period II. Sensitivity analysis indicates that the streamflow alteration was most sensitive to changes in landscape parameters. The aridity index and all the elasticities showed an obvious increasing trend from the upstream to the downstream in the TRB. Our study suggests that it is important to take effective measures for sustainable development of eco-hydrological and socio-economic systems in the TRB.
RESUMO
The Tarim River is the longest inland river at an arid area in China. Deterioration in its ecohydrological system has received much attention world widely. This study presents quantitative assessment of hydrological alterations in the hydrological regime of the Tarim River caused by reservoir irrigation and channel irrigation over a period of over a half century. The improved indicators of hydrologic alteration and range of variability approach were applied to the daily flow rates at the two representative hydrological stations. Our study shows that the annual extreme water conditions (1-, 3-, 7-day annual minimum and extreme low timing) have been altered, compared with the pre-impact period. The average flow rate in July, the 30-day annual maximum flow rates, the date for the maximum rate, the rise rate, and the fall rate show a significant decreasing trend. The improved overall degree of hydrological alteration for the two stations are approximately 68.7% and 61.8%, suggesting a high degree of alteration. This study greatly improved our understanding of impacts of irrigations on the ecohydrological characteristics in the Tarim River.
RESUMO
Landscape ecological characteristics of the urban-rural ecotone of Nanjing City were studied by using remote sensing and geographical information system (GIS) techniques. Two representative study regions with the same area were chosen in the eastern and southern part of the city. The urban-rural fringe of both east (URFE) and south region (URFS) can be divided into three zones: fringe-paraurban zone, transition zone and pararural zone. URFE was basically characterized by low landscape diversity, dominance and fragmentation. The forest patches in URFE had larger area and average perimeter, while their average fractal dimension, average stretched index and separated degree were lower. The average area of vegetable land and paddy land was larger than that of south region. URFS showed higher landscape diversity, dominance and fragmentation, more and higher density of patches. The area and the perimeter of water and architectural patches in URFS were also larger than that of URFE. The relationship between patch area and fractal dimension, stretched index and fractal dimension, patch number and area were discussed. The function and contributing factors of each type of patches, especially forestland, and the landscape characteristics and the ecological significance of corridors including road, river, and city wall of urban-rural fringe were also analyzed.
