黄 光偉

Hydrological drought (HD) characterization with different return periods is essential to appropriately design the best water management practices. In particular, characterizing the interactive relations of discharge, drought, and return periods using a novel triple diagram can deepen the interpretation of regional droughts, which have not been adequately considered, especially in semi-arid areas. Considering the critical role of HD in water exploitation and management in Iran, this study was therefore conducted to analyze the HD in different return periods in rivers of the Ardabil Province (area = 17,953 km2). To this end, the streamflow drought index (SDI) was computed using DrinC software at 1-, 3-, and 6-month time scales for 25 hydrometric stations during 1981–2014. Then, the drought severity was evaluated by CumFreq software in different return periods (2, 5, 10, 25, 50, and 100 years). Finally, the relationship between discharge, SDI, and return periods was analyzed using triple diagram models. The results revealed that the drought events had mild (−1 ≤ SDI < 0) and moderate (−1.5 ≤ SDI < −1) severity for most study stations in the study area. The mean values of SDI in the 1-, 3-, and 6-month time scales were 1.08, 0.80, and 0.55, respectively. At all study time scales, the drought severity in both rivers with low and high flows increased with increasing return periods. In such a way, the maximum drought severity has been found for rivers with high flow at a 100-year return period. The current results can be considered a screening tool for the distinctive conservation and directive management of watershed resources.

It is a well-accepted notion that women are more vulnerable to natural disasters than men, especially in developing countries. However, in developed countries, how women’s empowerment by economic and social development has reduced the gender gap in vulnerability remains insufficiently answered. As Japan passed its golden age, moving into an aging society, a study on how the gender difference in flood vulnerability has evolved can contribute to a better understanding of the types and causes of vulnerability, leading to better flood risk management in a new social context. Following this thinking, the present study conducted a longitudinal analysis using representative flooding cases in Japan over a period of forty years. It found that the women’s fatality rate increased with age much faster than men’s in the 1980s but reversed in a recent major flood disaster. It also revealed that most flood disaster victims were elderly in recent years. These findings suggest that the flood vulnerability at present is more driven by age-related physical ability decline, much less relevant to gender. Based on the results, it proposed a new framework for assessing flood vulnerability in an aging society. Such outcomes can help with the better formulation of flood management policies and probing into solutions.

An effective flood warning system is crucial for successful flood management. Flood warning systems have been developed in many countries across the world. However, scientific literature on flood warning systems has been mainly focused on technical capacity building, and the effectiveness of warning systems in mobilizing evacuation was much understudied. Japan is a country with a long history of fighting against flood disasters; the evaluation of its practices in providing flood warnings and the effectiveness are certainly important for further flood research development in Japan, and sharing the experience and lessons with the rest of the world will contribute to flood damage reduction on a global scale. Following this line of thinking, this article is intended to present a clear and concise picture of the current flood warning system in Japan, which has been poorly documented up until now. It is also aimed at providing a performance assessment for the flood warning system through case study approach and the use of Strengths, Weaknesses, Opportunities, and Threats (SWOT) model. Through analyses, the pros and cons of the current flood warning system in Japan are highlighted, and the directions for further development and refinement are explained.

The occurrence and intensity of climatic and hydrologic extreme events, as indicators of climate change, are increasing in most parts of arid and semi-arid regions, including Ardabil province, Iran. Recent studies have revealed the need for the multidimensional assessment of flood disasters in this area. Consequently, this present study was conducted to provide comprehensive information on the flood vulnerability of 26 watersheds in Ardabil province. Here, six components, including meteorological, hydrological, physical-environmental, social, economic, and countermeasures, were computed at a watershed scale based on 19 different criteria. Finally, the flood vulnerability index (FVI) for each watershed was calculated. The results revealed the need for different management approaches for flood hotspots based on the vulnerability to the six components studied. The integrated FVI showed that 46.97%, 33.63%, 18.10%, 1.20%, and 0.10% of the province have very high, high, medium, low, and very low flood vulnerability, respectively. The spatial mapping also revealed that all study areas were under flood stress, except small parts in central, east, and north. The preliminary version of the flood vulnerability atlas is presented, which estimates the flood disaster risk throughout the province. In addition, the developed regional framework in this study also allows for more comprehensive and extensive dataset analysis.

Knowledge of landscape fragmentation is known to be important in ecological integrity, hydrological processes, urban planning, sustainable land management, and policymaking. Recent anecdotal studies reveal a need for analytical quantification of landscape fragmentation at different levels. Therefore, the present study was conducted at KoozehTopraghi Watershed, Ardabil Province, Iran, where covers by different land uses/covers, to (a) explore the spatial pattern of landscape fragmentation metrics comprehensively in different scales, (b) distinguish the landscape fragmentation hot spots, and (c) investigate the spatial clustering of landscape fragmentation metrics. The behaviors of 7, 10, and 13 fragmentation metrics concerning three levels of patch, class, and landscape across 36 sub-watersheds were explored using principal component analysis (PCA) and expert elicitation. The Getis-Ord Gi* and local Moran’s I indices were also used to analyze the hot spots and clusters of landscape fragmentation, respectively. The results verified the high degree of spatial variability of the metrics in the three levels of fragmentation analysis. The class-level fragmentation analysis showed that the watershed is characterized by high-fragmented residential land use and low-fragmented dry farming land use. The spatial trend analysis at the landscape level further indicated that sub-watersheds 1, 2, 11, 21, to 26, and 34 to 36, mainly located in lowlands and central parts, allocated better status considering the fragmentation metrics rather than other parts of the watershed. The significant hot spots and high clusters of fragmentation also were distributed in different parts of the watershed in terms of various landscape metrics.