Paleoclimate studies and natural-resource management in the Murray-Darling Basin I: past,present and future climates

This paper provides an incisive review of paleoclimate science and its relevance to natural-resource management within the Murray-Darling Basin (MDB). The drought of 1997–2010 focussed scientific, public and media attention on intrinsic climate variability and the confounding effect of human activity, especially in terms of water-resource management. Many policy and research reviews make statements about future planning with little consideration of climate change and without useful actionable knowledge. In order to understand future climate changes, modellers need, and demand, better paleoclimate data to constrain their model projections. Here, we present an insight into a number of existing long-term paleoclimate studies relevant to the MDB. Past records of climate, in response to orbital forcing (glacial–interglacial cycles) are found within, and immediately outside, the MDB. High-resolution temperature records, spanning the last 10⁵ years, exist from floodplains and cave speleothems, as well as evidence from lakes and their associated lunettes. More recently, historical climate records show major changes in relation to El Niño–Southern Oscillation cycles and decadal shifts in rainfall regimes. A considerable body of research currently exists on the past climates of southeastern Australia but, this has not been collated and validated over large spatial scales. It is clear that a number of knowledge gaps still exist, and there is a pressing need for the establishment of new paleoclimatic research within the MDB catchment and within adjacent, sensitive catchments if past climate science is to fulfil its potential to provide policy-relevant information to natural-resource management into the future.     

Toward improved operational surge and inundation forecasts and coastal warnings

Coastal regions are vulnerable to storm surge and flooding due to tropical and extratropical storms. It is necessary to build robust resiliency of the coastal communities to these hazards. The main objectives of operational surge and inundation forecast and coastal warning systems are to protect life and to sustain economic prosperity. The National Oceanic and Atmospheric Administration of the United States has initiated an integrated effort through pilot demonstration projects, and model-based ocean and coastal forecasting systems, to build improved operational warnings and forecasts capability for storm surge and inundation. This note describes the overall strategy and progress to date, with an emphasis on forecasting extratropical storm surge.     

An integrated flood inundation model for coastal urban watershed of Navi Mumbai,India

Most urban agglomerations located in the Mumbai coastal region in India are vulnerable to flooding due to increasing frequency of the short-duration heavy rainfall, by virtue of their location at foothills on one side and tidal variations on the other side. Steep slopes in the catchment ensure fast runoff and tidal variation adds to backwater effect in the drainage system, which together are favorable for flooding. The present study simulates the flood inundation due to heavy rainfall and high-tide conditions in a coastal urban catchment within Mumbai region with detention pond. Overland flow is modeled using a mass balance approach, which can adapt to hilly slopes and smoothly accommodate detention pond hydraulics. Dynamic wave channel routing based on finite element method captures the backwater effects due to tidal variation, and raster-based flood inundation model enables direct use of digital elevation model. The integrated model is capable of simulating detention pond hydraulics within the raster flood model for heavy rainfall events. The database required for the model is obtained from the geographical information system (GIS) and remote sensing techniques. Application of the integrated model to literature problems and the catchment of the study area for two non-flooding events gave satisfactory results. Further, the model is applied to an extreme rainfall event of July 26, 2005, coinciding with high-tide conditions, which revealed vulnerability of the area to flooding despite of an existing detention pond. A sensitivity analysis on the location of detention pond indicated that catchment response can be better governed by relocating the detention pond to upstream of existing detention pond especially when heavy rainfall events are becoming frequent.     

Flood risk assessment in a coastal lagoon under present and future scenarios: Ria de Aveiro case study

Iranian strong motion records as well as detailed conditions of their instrument sites and the characteristics of their causative seismic sources are compiled and processed. The dataset consists of 2286 three-component records from 461 Iranian earthquakes with at least two high-quality records having moment magnitude from 3.9 to 7.3. These records are about 20% of the Iranian database and are suitable for seismic hazard analysis and engineering applications. Perhaps for the first time in the literature, the distance to the surface projection of the fault is reported for a great number of records corresponding to earthquakes with M > 6.0. The raw accelerations are processed using the wavelet de-noising method. Having corrected and filtered these raw data, the pseudospectral accelerations are calculated for each of the three components of time series, separately. In addition to the ground motion parameters, a large and comprehensive list of metadata characterizing the recording conditions of each record is also developed. Moreover, careful revision of the characteristics of the earthquakes such as location, magnitude, style of faulting and fault rupture plane geometry, if available, is carried out using the best available information in a scientifically sound manner. Finally, we also focus on special ground motion records including records with peak ground acceleration (PGA) >300 cm/s² and distances less than 30 km. These are “exceptional” records in the Iranian dataset and include less than 2% of the selected dataset.     

MERLIN: a flood hazard forecasting system for coastal river reaches

Natural Hazards - This study presents MERLIN, an innovative flood hazard forecasting system for predicting discharges and water levels at flood prone areas of coastal catchments. Discharge...     

World water resources,present and future

The earth's hydrologic cycle sets the hydrosphere in motion and continuously renews freshwater reserves. In compiling maps of different water resources, the six-component method (equation) of water balance, suggested by the author, is used instead of the three-component one. Water resources transformation carried out on a large scale with the help of different methods, assists in preserving these reserves for the future. On the basis of an analysis of the present state of world water resources and alternative forecasts for the year 2000, the author concludes that it is of primary importance to reduce and eventually to cease the dumping of wastewaters into rivers and bodies of water and to isolate polluted water from the natural hydrologic cycle.     

From natural hazard to environmental catastrophe: Past and present

The number of environmental catastrophes is rising, mostly owing to an increase in hydrometeorological hazards. The number of disasters is escalating as the world population grows and people settle in marginal areas. In order to improve preparedness, the geological and archaeological records must be investigated as they hold a wider range of possible events than the much shorter instrumental record. Catastrophes will gain amplitude with rapid onset, long duration, larger affected area, inflexible society and, of course, convergence of threats. Too often, it seems that today's societies resist learning from the past and therefore tend to repeat errors. A new field of science is emerging: the science of environmental catastrophes, which requires not only robust chronologies to firmly link cause and effect, but also bridges the crossing between the geosciences and social sciences.     

A continuous simulation approach for the estimation of extreme flood inundation in coastal river reaches affected by meso- and macrotides

Considering the joint probability of occurrence of high sea levels and river discharges, as well as the interactions between these sources of flooding, is of major importance to produce realistic inundation maps in river reaches affected by the sea level. In this paper, we propose a continuous simulation method for the estimation of extreme inundation in coastal river reaches. The methodology combines the generation of synthetic long-term daily time series of river discharge and sea level, the downscaling of daily values to a time resolution of a few minutes, the computation of inundation levels with an unsteady high-resolution two-dimensional model and the use of interpolation techniques to reconstruct long-term time series of water surface from a limited number of characteristic cases. The method is especially suitable for small catchments with times of concentration of a few hours, since it considers the intradiurnal variation of river discharge and sea level. The methodology was applied to the coastal town of Betanzos (NW of Spain), located at a river confluence strongly affected by the sea level. Depending on the return period and on the control point considered, the results obtained with the proposed methodology show differences up to 50 cm when compared with the standard methodology used in this region for the elaboration of flood hazard maps in accordance with the requirements of the European Directives. These results indicate the need for adaption of the standard methodology in order to produce more realistic results and a more efficient evaluation of flood hazard mitigation measures.     

Methodological study of coastal geological hazard assessment based on GIS

The current researches on risk assessment of geological disasters mainly focus on unexpected disasters such as collapses, landslides and mud-rock flows etc. As the convergence zone of land and sea, coastal zone is the most active and complex area of interactions of lithosphere, hydrosphere, atmosphere, biosphere and anthroposphere. The ecological environment of coastal zone is very fragile, so further systematical research on coastal geological hazard assessment and prevention is in urgent need. The author begins with the definition and research contents and selects three typical coastal geological disasters, namely, the seawater intrusion, coastline change and sea-level rise as the objects of study. The systematic analysis and study on assessment system and methods are conducted, hazard assessment factors are selected, and a completely set of coastal disaster assessment system is established based on the technique of GIS. We took Bao’an District of Shenzhen City as an example and carried out a case study.     

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.     

Evaluation of approaches to calculate debris-flow parameters for hazard assessment

Many different runout prediction methods can be applied to estimate the mobility of future debris flows during hazard assessment. The present article reviews the empirical, analytical, simple flow routing and numerical techniques. All these techniques were applied to back-calculate a debris flow, which occurred in 1982 at La Guingueta catchment, in the Eastern Pyrenees. A sensitivity analysis of input parameters was carried out, while special attention was paid to the influence of rheological parameters. We used the Voellmy fluid rheology for our analytical and numerical modelling, since this flow resistance law coincided best with field observations. The simulation results indicated that the “basal” friction coefficients rather affect the runout distance, while the “turbulence” terms mainly influence flow velocity. A comparison of the velocity computed on the fan showed that the analytical model calculated values similar to the numerical ones. The values of our rheological parameters calibrated at La Guingueta agree with data back-calculated for other debris flows. Empirical relationships represent another method to estimate total runout distance. The results confirmed that they contain an important uncertainty and they are strictly valid only for the conditions, which were the basis for their development. With regards to the simple flow routing algorithm, this methods could satisfactorily simulate the total area affected by the 1982 debris flow, but it was not able to directly calculate total runout distance and velocity. Finally, a suggestion on how different runout prediction methods can be applied to generate debris-flow hazard maps is presented. Taking into account the definition of hazard and intensity, the best choice would be to divide the resulting hazard maps into two types: “final hazard maps” and “preliminary hazard maps”. Only the use of numerical models provided final hazard maps, because they could incorporate different event magnitudes and they supplied output-values for intensity calculation. In contrast, empirical relationships and flow routing algorithms, or a combination of both, could be applied to create preliminary hazard maps. The present study only focussed on runout prediction methods. Other necessary tasks to complete the hazard assessment can be looked up in the “Guidelines for landslide susceptibility, hazard and risk zoning” included in this Special Issue.     

环境地质学进展与展望

环境地质学是随着人类活动和地质环境之间相互作用的不断加深而形成和发展的。自５０年代起,我国开展了大量的环境地质工作,未来环境地质学有着广阔的研究领域。环境地质学研究是可持续发展战略的一部分     

Numerical simulation of tsunamis — Its present and near future

Hindcasting of a tsunami by numerical simulations is a process of lengthy and complicated deductions, knowing only the final results such as run-up heights and tide records, both of which are possibly biased due to an insufficient number of records and due to hydraulic and mechanical limitation of tide gauges. There are many sources of error. The initial profile, determined with seismic data, can even be different from the actual tsunami profile. The numerical scheme introduces errors. Nonlinearity near and on land requires an appropriate selection of equations. Taking these facts into account, it should be noted that numerical simulations produce satisfactory information for practical use, because the final error is usually within 15% as far as the maximum run-up height is concerned.The state-of-the-art of tsunami numerical simulations is critically summarized from generation to run-up. Problems in the near future are also stated. Fruitful application of computer graphics is suggested.     

我国地质灾害防治工程的边坡绿化技术与现状

近年来,我国地质灾害防治工程,更注重工程建设与环境保护相互协调发展,强化了防治工程的绿色环保意识,使地质灾害治理与生态环境保护成为一个相辅相成的统一体,实现人与自然的和谐.为了恢复工程建设中因开挖大量边坡而遭到破坏的植被,我国在灾害治理和边坡防护工程中的生态防护技术方法及边坡绿化的草种选择方面有了长足的进步.目前边坡生态治理常用的方法主要有6大类植生卷铺盖法、挂三维网植草、液压喷播、生态多孔混凝土绿化法、浆砌空心砖培土种草及喷混植草.边坡绿化草种的选择,应考虑边坡的地域、气候、土壤、当地植被,绿化的持续年限(防止植被的退化),以及与周围环境的协调.