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 .     

Methodology for the analysis of causes of drought vulnerability on the River Basin scale

The concept of vulnerability has emerged in recent decades as a key concept for the research on drought risk as well as in the implementation of mitigation strategies of drought risk. The context within which this concept emerges is one of scientific consensus: the research community agrees that we are witnessing a paradigm shift in water management policies, within a broader framework of changes in the relationship between humans and nature. In this context, vulnerability studies must become an instrument for the assessment and mitigation of risk. Based on the proposals put forward by the IPCC concerning the components of vulnerability (exposure, sensitivity and adaptive capacity), this paper proposes a methodology for the evaluation and analysis of drought vulnerability on the river basin scale. The methodology results in the calculation of a Drought Vulnerability Index (DVI) and the use of different techniques for the interpretation of results.     

Assessment of drought hazard impact on wheat cultivation using standardized precipitation index in Iran

The assessment of drought hazard impacts on wheat cultivation as a strategic crop in Iran is essential for making mitigation plans to reduce the impact of drought. Standardized precipitation index has gained importance in recent years as a potential drought indicator and is being used more frequently for assessment of drought hazard in many countries. In the present study, the calculated standardized precipitation index for 48 stations dataset in the 30-year time scale fulfilled 30 statistical matrices. The drought hazard index map was produced by sum overlaying the spatial representations of 30 statistical matrices and categorized into four levels of low, moderate, high, and very high, which demonstrated probability of drought occurrences of 10–20 %, 20–30 %, 30–40 %, and 40–50 %, respectively. Finally, after the general division of zonal statistics in drought hazard index map of Iran, major drought hazard zones were geographically classified into five zones. The statistical analysis showed a significant correlation (R ²?=?0.701 to 0.648) between drought occurrences and wheat cultivation including surface area and total production for these drought hazard zones.     

Erratum to: Methodology for the analysis of causes of drought vulnerability on the River Basin scale

An inclinometer is a high-precision instrument used to detect displacement along sliding zones. From the time the inclinometer pipe is embedded to inclinometer calibration and to measured data collection and processing, many errors or misjudgments can occur that affect the measurement data. The most important objective for correctly using the observation results is the accurate interpretation of the horizontal displacement profiles obtained from the observation. This study combines existing inclusive data accumulated by a monitoring system on a test sloping site in a campus. It focuses on a comprehensive interpretation of the displacement relationships among different monitoring instruments. This study uses data interpretation principles, categorizes different mechanisms, and performs quantitative analysis and discussion in order to determine the significance presented by various types of monitored information in terms of slope sliding. In addition, in this study, stairwells in a campus building are used, an inclinometer is set up, and calibration equipment for the experiment is added in order to simulate various configurations and observe patterns for displacement curves. The examples for the various conditions include empty holes in the backfill around the pipe, connection points falling off, pipe torsion, relative sliding between layers reaching an extreme condition and leading to stuck pipes, multi-layered sliding, and different thicknesses in sliding zones. The experiment illustrates changes in behavior in terms of environmental factors. The results can be used for instrument calibration and measurement, and as a reference for disaster warning and prevention in hazardous areas with slopes.     

Assessment of flood hazard,vulnerability and risk of mid-eastern Dhaka using DEM and 1D hydrodynamic model

Floods are regular feature in rapidly urbanizing Dhaka, the capital city of Bangladesh. It is observed that about 60% of the eastern Dhaka regularly goes under water every year in monsoon due to lack of flood protection. Experience gathered from past devastating floods shows that, besides structural approach, non-structural approach such as flood hazard map and risk map is effective tools for reducing flood damages. In this paper, assessment of flood hazard by developing a flood hazard map for mid-eastern Dhaka (37.16 km²) was carried out by 1D hydrodynamic simulation on the basis of digital elevation model (DEM) data from Shuttle Radar Topography Mission and the hydrologic field-observed data for 32 years (1972–2004). As the topography of the area has been considerably changed due to rapid land-filling by land developers which was observed in recent satellite image (DigitalGlobe image; Date of imagery: 7th March 2007), the acquired DEM data were modified to represent the current topography. The inundation simulation was conducted using hydrodynamic program HEC-RAS for flood of 100-year return period. The simulation has revealed that the maximum depth is 7.55 m at the southeastern part of that area and affected area is more than 50%. A flood hazard map was prepared according to the simulation result using the software ArcGIS. Finally, to assess the flood risk of that area, a risk map was prepared where risk was defined as the product of hazard (i.e., depth of inundation) and vulnerability (i.e., the exposure of people or assets to flood). These two maps should be helpful in raising awareness of inhabitants and in assigning priority for land development and for emergency preparedness including aid and relief operations in high-risk areas in the future.     

The paleohydrological context of the Iron Age floodplain sites of the Mun River Valley,Northeast Thailand1

Many Iron Age sites on the flood plain of the Mun River in northeast Thailand are encircled by channels commonly known as “moats.” Also, the sites are closely associated with complex paleochannels of the river. A comparison between the seemingly human‐constructed moats and paleochannels provided an opportunity to assess the relationship between prehistoric human settlement and paleohydrological conditions. In this study, the results of physical, sedimentological, and geochemical analyses are used to characterize sediments deposited within the channels around the Iron Age site of Ban Non Wat and within a paleochannel at nearby Ban Non Ngiu. This allowed us to test the results of previous research that has suggested significant changes in the floodplain hydrology and the geoarchaeologically important conclusion that Iron Age human activity was associated with one particular paleohydrological phase. Our analyses broadly confirm the results of previous stratigraphic studies, but add detail regarding sedimentation processes. The evidence indicates that there are significant sedimentological differences within the complex of archaeological channel features, differences that provide critical evidence for the formation and sedimentation processes of the channels. More importantly, comparison between the archaeological features and the natural channel fills highlights the relationships between the archaeological sites and landscape. Drawing also on previously published chronological, geomorphological, and stratigraphical data, it is possible to place the sites into a floodplain hydrological regime that may have been unique to the Iron Age. Specifically, the moats may have been constructed in response to enhanced water availability on the floodplain. The sites, therefore, may reflect a human response to increased availability of water beyond the main river channels. This water supply, however, appears to have been short‐lived (centuries at most), and with its loss, the human adaptation to this enhanced natural resource became unviable. © 2008 Wiley Periodicals, Inc.     

Assessment of physical vulnerability to agricultural drought in China

Food security has drawn great attention from both researchers and practitioners in recent years. Global warming and its resultant extreme drought events have become a great challenge to crop production and food price stability. This study aimed to establish a preliminary theoretical methodology and an operational approach for assessing the physical vulnerability of two wheat varieties (“Yongliang #4” and “Wenmai #6”) to agricultural drought using Environmental Policy Integrated Climate model (EPIC). Drought hazard index was set up based on output variables of the EPIC water stress (WS), including the magnitude and duration of WS during the crop-growing period. The physical vulnerability curves of two wheat varieties to drought were calculated by the simulated drought hazard indexes and loss ratios. And the curve’s effect on drought disaster risk was defined as A, B and C sections, respectively. Our analysis results showed that (a) physical vulnerability curves varied between two wheat varieties, which were determined by genetic parameters of crops; (b) compared with spring wheat “Yongliang 4#” winter wheat “Wenmai 6#” was less vulnerable to drought under the same drought hazard intensity scenario; (c) the wheat physical vulnerability curve to drought hazard displayed a S shape, suggesting a drought intensity–dependent magnifying or reducing effect of the physical vulnerability on drought disasters; (d) the reducing effect was mainly in the low-value area of vulnerability curve, whereas the magnifying effect was in the middle-value area, and the farming-pastoral zone and the Qinling Mountain–Huaihe River zone formed important spatial division belts.     

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 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.

     

Farmers, foresters and forest temples: conservation in the Dong Mun uplands, Northeast Thailand

Between 1970 and 1980 villages adjacent to the Dong Mun Uplands of Northeastern Thailand were transformed from subsistence communities, based on wet rice production, to a cash economy linked to global markets and the national and international political order. Although formally designated reserves had been created on old growth forests, the new economic opportunities encouraged conversion of forests to agriculture. Attracted by a false belief that land was being made available for settlement, immigrants flooded in and cleared forests to plant dryland cash crops using the newly expanded and improved road network to export their products. Social forestry programs may have assisted community development and encouraged agricultural diversification but were insufficient to prevent the contraction of forests, which now remain only as degraded remnants on the steepest slopes and least accessible sites.To some extent the social, political and economic forces have stabilized in Dong Mun and evidence of a new relationship between humans and their forest land is appearing. The Royal Forest Service is largely reconciled to the loss of domain over most of forest reserve and is pursuing a modified management policy that shows some evidence of a shift from an industrial to a post-industrial mode.In recent years, Buddhist monks in forest temples found through the uplands have achieved some effective forest conservation and restoration. Their efforts stem from the Buddhist precepts of the sanctity of all life and a view that forests are places for contemplation and spiritual renewal. Monks have been able to protect and restore some forest land because their views and wishes are far more likely to be honored than laws and demands of government officials. This reflects a broader phenomenon in Thailand where considerable impetus for a contemporary environmental movement has come from religious sources in contrast to the west where it is largely a secular in origin.     

Conceptual and numerical models for sustainable groundwater management in the Thaphra area, Chi River Basin, Thailand

Sustainable management of groundwater resources is vital for development of areas at risk from water-resource over-exploitation. In northeast Thailand, the Phu Thok aquifer is an important water source, particularly in the Thaphra area, where increased groundwater withdrawals may result in water-level decline and saline-water upconing. Three-dimensional finite-difference flow models were developed with MODFLOW to predict the impacts of future pumping on hydraulic heads. Four scenarios of pumping and recharge were defined to evaluate the system response to future usage and climate conditions. Primary model simulations show that groundwater heads will continue to decrease by 4–12?m by the year 2040 at the center of the highly exploited area, under conditions of both increasing pumping and drought. To quantify predictive uncertainty in these estimates, in addition to the primary conceptual model, three alternative conceptual models were used in the simulation of sustainable yields. These alternative models show that, for this case study, a reasonable degree of uncertainty in hydrostratigraphic interpretation is more impactful than uncertainty in recharge distribution or boundary conditions. The uncertainty-analysis results strongly support addressing conceptual-model uncertainty in the practice of groundwater-management modeling. Doing so will better assist decision makers in selecting and implementing robust sustainable strategies.     

Evaluation of CHIRPS and its application for drought monitoring over the Haihe River Basin,China

To establish the drought index objectively and reasonably and evaluate the hydrological drought accurately, firstly, the optimal distribution was selected from nine distributions (normal, lognormal, exponential, gamma, general extreme value, inverse Gaussian, logistic, log-logistic and Weibull), then the Optimal Standardized Streamflow Index (OSSI) was calculated based on the optimal distribution, and last, the spatiotemporal evolution of hydrological drought based on the OSSI series was investigated through the monthly streamflow data of seven hydrological stations during the period 1961–2011 in Luanhe River basin, China. Results suggest: (1) the general extreme value and log-logistic distributions performed prominently in fitting the monthly streamflow of Luanhe River basin. (2) The main periods of hydrological drought in Luanhe River basin were 148–169, 75–80, 42–45, 14–19 and 8–9 months. (3) The hydrological drought had an aggravating trend over the past 51 year and with the increase in timescale, the aggravating trend was more serious. (4) The lower the drought grade was, the broader the coverage area. As for the Luanhe River basin, the whole basin suffered the mild and more serious drought, while the severe and more serious drought only cover some areas. (5) With the increase in time step, the frequency distribution of mild droughts across the basin tended to be concentrated, the frequency of extreme droughts in middle and upper reaches tended to increase and the frequency in downstream tends to decrease. This research can provide powerful references for water resources planning and management and drought mitigation.     

Assessment and mapping of the intrinsic vulnerability to pollution: an example from Keritis River Basin (Northwestern crete, Greece)

Due to the geological and hydrogeological characteristics, the carbonate aquifers are frequently vulnerable to natural and/or anthropogenic polluting sources. The aim of the present study is to evaluate the intrinsic vulnerability to pollution of the Keritis River Basin (northwestern Crete, Greece). The huge amount of the flowing groundwater represents a strategic water resource to be allocated to drinking water purpose and to agricultural activities, too. The studied groundwater are characterized by quality degradation processes represented by the anthropogenic and natural pollution such as olive oil farming, agriculture activities, industrial waste and salt water intrusion. For a better management and protection of the water resources, the assessment and mapping of groundwater vulnerability to pollution are very important. From this investigation, the Keritis Basin showed an intrinsic vulnerability degree from extremely high to very low. This study allows to define the strategies which will permit a proper safeguard criteria, against the pollution sources of the Keritis Basin groundwater resources.     

Measuring individual vulnerability to floods in the lower and middle Grijalva River Basin,Tabasco, Mexico

Natural Hazards - We built an easy-to-interpret individual vulnerability index to floods that is amenable for empirical testing and may be adapted to any perceived hazard or ecological setting. An...     

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。     

Social vulnerability index for coastal communities at risk to hurricane hazard and a changing climate

This paper presents the development of the Coastal Community Social Vulnerability Index (CCSVI) in order to quantify the social vulnerability of hurricane-prone areas under various scenarios of climate change. The 2004–2005 Atlantic hurricane seasons is estimated to have caused 150 billion dollars in damages, and in recent years, the annual hurricane damage in the United States is estimated at around150 billion dollars in damages, and in recent years, the annual hurricane damage in the United States is estimated at around 6 billion. Hurricane intensity or/and frequency may change due to the increase in sea surface temperature as a result of climate change. Climate change is also predicted to cause a rise in sea levels, potentially resulting in higher storm surges. The CCSVI combines the intensity of hurricanes and hurricane-induced surge to create a comprehensive index that considers the effects of a changing climate. The main contributing factors of social vulnerability (such as race, age, gender, and socioeconomic status) in hurricane-prone areas are identified through a principal components analysis. The impact of social characteristics on the potential hurricane damage under various scenarios of climate change are evaluated using Miami-Dade County, Florida, as a case study location. This study finds that climate change may have a significant impact on the CCSVI.     

Effects of human activities on hydrological drought patterns in the Yangtze River Basin,China

Natural Hazards - As an extremely important region for the socioeconomic development of China, the Yangtze River Basin (YRB) is vulnerable to climate change and natural disasters. In recent...     

Comparative study on flash flood hazard assessment for Nam Ou River Basin,Lao PDR

Natural Hazards - Laos is a mountainous, rainy and less developed country in Southeast Asia. In Laos, floods represent a major constraint on social economic development, causing a large number of...     

Research on eco-environmental vulnerability evaluation of the Anning River Basin in the upper reaches of the Yangtze River

The Anning River Basin is located in the transitional zone of the Qinghai-Tibet Plateau, Yunnan-Kweichow Plateau and Sichuan Basin. This transitional zone is an important ecological barrier of the upper reaches of the Yangtze River and plays a significant role in the ecological security and ecological construction of Sichuan Province. However, the innate vulnerability of the eco-environment combined with the unreasonable development and use of minerals, hydropower, agriculture and animal husbandry resources contribute to prominent eco-environmental problems. In support of remote sensing and geographical information system, this study uses the spatial principal component analysis (SPCA) method to build the evaluation model for the vulnerability evaluation and analysis of the eco-environment in the Anning River Basin. The following indicators are selected for the SPCA: elevation, slope, vegetation index, land use, soil type, soil erosion, precipitation, temperature, and population density. Thereafter, the first four principal components are selected and their corresponding weights are determined. The eco-environmental vulnerability comprehensive index of the Anning River Basin is calculated by using these data. According to the calculated results, the eco-environmental vulnerability of the Anning River Basin is divided into five levels, namely, potential vulnerability, slight vulnerability, light vulnerability, moderate vulnerability, and high vulnerability. Eco-environmental changes for the past 20 years (from 1990 to 2010) are discussed and analyzed as well as the driving forces. The analysis shows that the eco-environmental vulnerability of the Anning River Basin is at the moderate level, and exhibits obvious vertical distribution characteristics. The main reasons that cause eco-environmental changes are mainly human factors, socioeconomic factors, and environmental protection policies like “Natural Forests Protection” and “Grain-for-Green”. Based on the vulnerability classification results, the Anning River Basin is divided into three partitions for different degrees of eco-environmental reconstruction and protection, which provides foundation for the local eco-environmental reconstruction so as to reconstruct in order of the importance and urgency.