Assessment on agricultural drought vulnerability in the Yellow River basin based on a fuzzy clustering iterative model

Drought is one of the major natural disasters occurring in China and causes severe impacts on agricultural production and food security. Therefore, agricultural drought vulnerability assessment has an important significance for reducing regional agricultural drought losses and drought disaster risks. In view of agricultural drought vulnerability assessment with the characteristics of multiple factors and uncertainty, we applied the fuzzy comprehensive evaluation framework to agricultural drought vulnerability model. The agricultural drought vulnerability assessment model was constructed based on the multi-layer and multi-index fuzzy clustering iterative method, which can better reveal the drought vulnerability (including sensitivity and adaptation capacity). Furthermore, the cycle iterative algorithm was used to obtain the optimal index weight vector of a given accuracy by setting the objective function. It provides a new approach to weight determination of agricultural drought vulnerability assessment. In this study, agricultural drought vulnerability of 65 cities (as well as leagues and states) in the Yellow River basin was investigated using a fuzzy clustering iterative model and visualized by using GIS technique. The results showed clear differences and regularities among the spatial distribution of agricultural drought vulnerability of different regions. A large number of the regions in the basin consisted of those exhibiting high to very high vulnerability and were mainly distributed throughout Qinghai, Gansu, northern Shaanxi, and southern Shanxi, accounting for 46 % of the total assessment units. However, the regions exhibiting very high vulnerability were not significantly affected by droughts. Most of the regions exhibiting moderate vulnerability (21.5 % of the assessment units) were mainly concentrated among agricultural irrigation areas, where agriculture is highly sensitive to droughts, and drought occurrence in these regions will likely cause heavy losses in the future. The regions exhibiting slight to low vulnerability were relatively concentrated, accounting for 32.3 % of the assessment units, and were mainly distributed in the plains of the lower reaches of the Yellow River, where the economy was rather well developed and the agricultural production conditions were relatively stronger.     

Assessment of provincial social vulnerability to natural disasters in China

Assessment of social vulnerability has been recognized as a critical step to understand natural hazard risks and to enhance effective response capabilities. Although significant achievements have been made in social vulnerability researches, little is know about the comprehensive profile of regional social vulnerability in China. In this study, the social vulnerability to natural hazards was firstly divided into socioeconomic and built environmental vulnerability. Then, using factor analysis, we identified the dominant factors that influence the provincial social vulnerability in China to natural hazards based on the socioeconomic and built environmental variables in 2000 and 2010 and explored the spatial patterns of social vulnerability. The results indicated that the provincial social vulnerability in China showed significant regional differences. The social vulnerability in the southeastern and eastern regions of China was greater than its northern and central parts over the past decade. Economic status, rural (proportion of agricultural population and percentage of workers employed in primary industries), urbanization, and age structure (children) were the dominant driving forces of variations in provincial socioeconomic vulnerability in two studied years, while lifelines and housing age could explain most of changes in built environmental vulnerability in 2000 and 2010. There were no statistically significant correlations between social vulnerability and disaster losses (p > 0.05), indicating the impact of disasters was also related to the intensity of hazards and exposure. Disaster relief funds allocated to each province of China depended more on its disaster severity than the regional integrated social vulnerability over the past decade. These findings would provide a scientific base for the policy making and implementation of disaster prevention and mitigation in China.     

Assessing agricultural and hydrological drought vulnerability in a savanna ecological zone of Sub-Saharan Africa

Natural Hazards - Despite measures to mitigate drought, study on the extent of agricultural and hydrological drought vulnerability is still neglected in the savanna ecological zone of Nigeria. This...     

中国农业干旱脆弱性分区研究

根据各地水资源的特点、农业受旱成灾的情况及水利设施抗旱能力,确定农业干旱脆弱性分区的原则和指标,构造层次分析模型。应用MapInfo6.0软件绘制了中国农业干旱脆弱性分区图,结果表明:在全国340个农业干旱脆弱性分区中,极严重脆弱区47个,严重脆弱区104个,一般脆弱区175个,轻度脆弱区14个。     

Assessment of physical vulnerability and potential losses of buildings due to shallow slides

Physical vulnerability (PV) of buildings and associated potential losses (PLs) due to the occurrence of shallow slides are semi-quantitatively assessed at the regional scale in a municipality located in the North of Portugal. This work has four main purposes: (1) to identify and characterize the built environment exposed to shallow slides in the study area; (2) to assess the PV of each building type taking into account the building resistance (BR) and the landslide magnitude (LM); (3) to evaluate the economic value (EV) of each single exposed building using cadastral and market values; and (4) to estimate PLs on buildings due to landslide activity. The analysis is made for each single building of the study area, and this is an innovative contribution of this work. The semi-quantitative methodology to assess PV of buildings exposed to shallow translational slides combines the LM and the BR, which is empirically obtained weighting a set of parameters related to building characteristics. The quantification of the EV of buildings was carried out using an adaptation of the calculation formula used by the Portuguese Tax Services to determine the taxable value of buildings in Portugal. PLs result from the product between PV of the exposed buildings and their EV in euros. The overlapping of PLs of buildings with an available landslide susceptibility map, although does not provides any quantified risk analysis, provides valuable information to be used by spatial planning and civil protection stakeholders.     

Identifying key factors of regional agricultural drought vulnerability using a panel data grey combined method

Regional agricultural drought vulnerability (RADV) is a complex problem caused by the interaction of various factors, and the combination of multiple dimensions of each subregion, factor index and time affects the RADV. Therefore, panel data should be used to reflect the actual situation of the region objectively and comprehensively. Current research on identifying key factors of affecting RADV is relatively scarce from the perspective of panel data. In view of this, in order to classify and identify the key factors, a new panel data grey combined method of comprehensive grey relational analysis (CGRA) and Max-CGRA clustering is proposed, which is applied to identify the key factors of RADV in China’s Henan Province. According to the identification results of key factors, the reasons for the change of RADV are further discovered, and the corresponding drought policies and countermeasures that need to be strengthened and controlled are presented. In addition, these results can also provide scientific basis for regional agricultural drought risk control.

     

Quantitative assessment and spatial characteristic analysis of agricultural drought risk in China

Based on the natural disaster analysis theory, the spatial characteristics of agricultural drought risk in China were investigated at 10 × 10 km grid scale. It shows that agricultural drought risk in China has a clear southeast–northwest spatial pattern. High and very high risk mainly occur in the eastern part of Northeast Plain, the central of Inner Mongolian Plateau, the Loess Plateau, north Xinjiang, the north and south of Yangtze Plain, and Yunnan-Guizhou Plateau. Statistics also show that 19.5 % of the main crop planting area is exposed to low risk, 35.1 % of the area to moderate risk, 39.8 % of the area to high risk, and 5.6 % of the area to very high risk. Further investigation shows that 23 % of total wheat growing areas is located in high and very high risk class; corn and rice are 16 % and 14 % respectively. Comprehensive analysis shows that severely affected areas by drought in the history are mainly located in the high and very high risk areas.     

Assessment of energy supply vulnerability between China and USA

USA and China are the two largest energy-consuming countries, and energy supply vulnerability is a prior topic on energy policy. Then, we develop energy supply vulnerability assessment index including the sustainability, the stability, the reliability, and the diversification indicators to assess and compare the change of energy supply vulnerability between China and USA based on the data in 2001–2010. We found that the fluctuations of energy supply vulnerability in China are more than those of USA. In 2001–2006, the index of China’s energy supply vulnerability presented a quick uptrend, but it presented a slow downtrend in 2007–2010 due to the uncertainty of some indicators; energy supply vulnerability of USA presented smaller change from 2000 to 2008 because of the stable and comprehensive energy supply system, but in 2009 and 2010, it became obviously less than those in other years due to the decline of energy consumption per capita. Additionally, Chinese energy supply also faces higher maritime transportation and geopolitical vulnerability than that of USA. The comparisons of the change of energy supply vulnerability between China and USA show that it is important to develop comprehensive energy supply system to reduce the uncertainty of main effect indicators, such as the control of energy consumption growth, and the diversification of energy supply and import.     

Assessment of energy supply vulnerability between China and USA

USA and China are the two largest energy-consuming countries, and energy supply vulnerability is a prior topic on energy policy. Then, we develop energy supply vulnerability assessment index including the sustainability, the stability, the reliability, and the diversification indicators to assess and compare the change of energy supply vulnerability between China and USA based on the data in 2001–2010. We found that the fluctuations of energy supply vulnerability in China are more than those of USA. In 2001–2006, the index of China’s energy supply vulnerability presented a quick uptrend, but it presented a slow downtrend in 2007–2010 due to the uncertainty of some indicators; energy supply vulnerability of USA presented smaller change from 2000 to 2008 because of the stable and comprehensive energy supply system, but in 2009 and 2010, it became obviously less than those in other years due to the decline of energy consumption per capita. Additionally, Chinese energy supply also faces higher maritime transportation and geopolitical vulnerability than that of USA. The comparisons of the change of energy supply vulnerability between China and USA show that it is important to develop comprehensive energy supply system to reduce the uncertainty of main effect indicators, such as the control of energy consumption growth, and the diversification of energy supply and import.

     

Assessment of regional drought vulnerability and risk using principal component analysis and a Gaussian mixture model

Due to the complex characteristics of drought, drought risk needs to be quantified by combining drought vulnerability and drought hazard. Recently, the major focus in drought vulnerability has been on how to calculate the weights of indicators to comprehensively quantify drought risk. In this study, principal component analysis (PCA), a Gaussian mixture model (GMM), and the equal-weighting method (EWM) were applied to objectively determine the weights for drought vulnerability assessment in Chungcheong Province, located in the west-central part of South Korea. The PCA provided larger weights for agricultural and industrial factors, whereas the GMM computed larger weights for agricultural factors than did the EWM. The drought risk was assessed by combining the drought vulnerability index (DVI) and the drought hazard index (DHI). Based on the DVI, the most vulnerable region was CCN9 in the northwestern part of the province, whereas the most drought-prone region based on the DHI was CCN12 in the southwest. Considering both DVI and DHI, the regions with the highest risk were CCN12 and CCN10 in the southern part of the province. Using the proposed PCA and GMM, we validated drought vulnerability using objective weighting methods and assessed comprehensive drought risk considering both meteorological hazard and socioeconomic vulnerability.

     

Analysis of social vulnerability to hazards in China

To improve natural disaster management, it is important to recognize the variability of the vulnerable populations exposed to hazards and to develop location-based emergency plans accordingly. This paper presents a mathematical model to establish a model of social vulnerability index (SoVI), which includes 12 social variables, and the regional social vulnerability to natural hazards was formulated by them. Taking a city as statistical unit, the variability of vulnerability to natural hazards was explored among the 323 cities based on the SoVI. The results indicate that vulnerability is a location-based regional phenomenon, with the most vulnerable cities being located in the southwest of China and the eastern areas being generally less vulnerable. The results will be helpful for policy makers to formulate disaster management plans, which can be beneficial for people in more vulnerable areas who are responding to, coping with, and recovering from natural disasters.     

张集地区地下水易污性及污染风险评价

文章在地下水易污性和污染风险评价方法的基础上,根据张集地区的水文地质状况和土地利用情况,建立了地区地下水易污性和污染风险评价的指标方法:GRADIC法和GRADICL法,并利用GIS/Arcinfo软件对地区地下水易污性和污染风险进行评价,得到张集地区地下水易污性指数和污染风险指数及其分布图。评价结果对于张集地区地下水合理开发利用、科学管理和有效保护,实现地区地下水资源的可持续利用具有实际意义。     

Assessment of eco-environment vulnerability in the northeastern margin of the Qinghai-Tibetan Plateau,China

The northeastern margin of the Qinghai-Tibetan Plateau is typically a vulnerable eco-environment where an overload of alpine meadows and serious soil degeneration have led to vulnerability to natural disasters. Consequently, this vulnerable eco-environment does not allow for rapid socioeconomic development, resulting in weak potential for sustainable development. The northeastern margin of the Qinghai-Tibetan Plateau in China is used for this case study, which sets up 17 impact factors of eco-environment vulnerability (EEV) to assess the indexes, including natural impact factors, economic impact factors and social impact factors. Subsequently, the study uses an analytic hierarchy process to endow index weights and proposes an assessment model of ^n P_i W_i /( _i = 1^n P_i W_i + _i = 1^n P_i W_i ) G = 1 - \sum\nolimits_{i = 1}^{n} {{{P_{i} \cdot W_{i} } /{( {\max \sum\nolimits_{i = 1}^{n} {P_{i} \cdot W_{i} } + \min \sum\nolimits_{i = 1}^{n} {P_{i} \cdot W_{i} } } )}}} to analyze and assess the dynamic changes in the EEV of the study area from 1987–2008. Finally, the correlation of the EEV and 17 impact factors is analyzed.     

Assessment of precipitation and drought variability in the Weihe River Basin,China

The amount and distribution of precipitation play crucial roles in the occurrence of drought in the Weihe River Basin (WRB), China. Using the precipitation data (1960–2010) of 21 meteorological stations, the spatial and temporal characteristics of short-, medium-, and long-term droughts on 3-, 6-, and 12-month time scales, respectively, were examined using the theory of runs and the Standardized Precipitation Index (SPI). The trends of the drought characteristics were analyzed by a modified Mann-Kendall (MMK) test method. Furthermore, comparative analysis of the SPI at different time scales was conducted. The results showed that (1) the main drought type was moderate drought, which occurred frequently in July and October; (2) the drought intensity and frequency were highest in the 1990s, and the drought severity and drought duration in the northwest was more serious than that in the east; (3) an increasing trend of short droughts appeared mainly in the spring and fall; an increasing trend of medium droughts mainly occurred in the 1990s and that of long-term droughts were mainly presented in the northwest region of the WRB; (4) SPI-3 can better reflect precipitation in the current month, SPI-6 has an advantage in characterizing drought persistence, and SPI-12 performs well in capturing extraordinary droughts; and (5) it was also observed that there is a strong relation between the precipitation distribution and drought zones in the basin, and the drought conditions changed continuously with the seasons depending upon the amount and spatial distribution of precipitation .