Blanca Adriana Botero

Landslides caused by rainfall are one of the most frequent causes of disasters in tropical countries and mountainous terrain and can block rivers generating landslide dams. This paper presents a methodology for the estimation of the obstruction of water streams generated by rainfall-induced shallow landslides. The spatial distribution of the landslide hazard was estimated in terms of the Factor of Safety (FoS) values using the deterministic method with physical basis SLIDE (Slope - Infiltration - Distributed Equilibrium). The rainfall regimes of the study area were estimated by means of a simple scaling Log Normal Model. Subsequently, the resulting areas with a high hazard level that could detach and reach the riverbed were identified as sources for the simulation of the debris flow runout using the Rapid Mass Movement Simulation model with its debris flow module, (i.e., RAMMS-DF), estimating zones of the riverbed that should be analyzed in detail. Finally, the effects of river chan...

"Los fenómenos naturales, y su impacto en la infraestructura y las comunidades, son unos de los temas más importantes y presentes en las agendas internacionales, y que, de acuerdo con el Programa Mundial de Evaluación de los Recursos Hídricos de la ONU, es una responsabilidad compartida que juega un papel fundamental en el desarrollo de las comunidades; más aún en tiempos donde los desastres naturales tienen un mayor impacto, debido a la exposición excesiva y a la vulnerabilidad de los elementos en riesgo en las zonas rurales, y al incremento en la frecuencia y severidad de los fenómenos naturales. Las consecuencias derivadas del cambio climático han provocado la aparición de amenazas de origen natural, tales como inundaciones, movimientos en masa y avenidas torrenciales, las cuales, a su vez, pueden desencadenar condiciones de riesgo si se considera que muchas comunidades, independientemente de su grado de desarrollo, son vulnerables desde múltiples perspectivas (sociales, económicas, ambientales, físicas) que les traen, como consecuencia, la pérdida de vidas humanas y de bienes materiales."

A quantitative flood risk assessment requires that vulnerability and hazard be evaluated quantitatively as well. In our research, we assess the flood risk of a south-east suburb of the city of Monteria Colombia. We proposed to assess vulnerability through damage functions development and their incorporation in the flood risk assessment. Risk is quantifying as expected annual economic loss. Vulnerability is estimated based on the relationship between the physical condition and the contents of the households, with their ability to resist flooding. Flood damages in movable property, structures and public areas were stablished through depth-damage functions. Data for construction of these depth damage functions were obtained through a survey and field observations of the entire selected area. In order to identify damage, we have taken advantage of the recent memory of the communities regarding their perception of real damages during a flood occurred in July 2010. Structural elements and movable assets were classified in categories and people were asked about damage in these categories. Additionally, the water marks on walls, doors and other structural elements were identified. In order to quantify hazard, we calibrate a simple hydrological model and a hydraulic model, based in the records and water marks left by the July 2010 flood. A quantitative risk model was applied that incorporates the quantitative risk and vulnerability estimation. Depth-damage functions developed are a useful tool that can be used in other regions in Colombia and Caribbean with similar socioeconomic and climatic conditions. Results shown that it is possible to typify the houses and the movable property by means of the construction of functions and it is possible to obtain the quantitative risk, contributing a practical tool for the urban planning of this zone of the city.

Historical records are an important source of information on extreme and rare floods and fundamental to establish a reliable flood return frequency. The use of long historical records for flood frequency analysis brings in the question of flood stationarity, since climatic and land-use conditions can affect the relevance of past flooding as a predictor of future flooding. In this paper, a detailed 400 yr flood record from the Tagus River in Aranjuez (central Spain) was analysed under stationary and non-stationary flood frequency approaches, to assess their contribution within hazard studies. Historical flood records in Aranjuez were obtained from documents (Proceedings of the City Council, diaries, chronicles, memoirs, etc.), epigraphic marks, and indirect historical sources and reports. The water levels associated with different floods (derived from descriptions or epigraphic marks) were computed into discharge values using a one-dimensional hydraulic model. Secular variations in f...

Non systematic information gives in flood frequency analysis more reliability for estimated quantiles. This type of information has been collected at different places in Spain, during the European project SPHERE. Two case studies were analyzed, the Onyar river at Gerona city, in which historical information was available, and Llobregat river where we had palaeofloods records. Two types of distribution functions have been used: 1) Without upper limit, choosing TCEV and GEV models and 2) With upper limit, where three distributions functions recently published in literature have been used: the EV4, the four parameters Lognormal with Slade transformation and Gumbel with Eliasson transformation. This type of distribution function has been applied to the extreme frequency analysis of annual maximum daily precipitation by some authors, however all of them assume that the value of upper limit is previously known in order to improve the quantile estimates. In this work the PMF was estimated as one more parameter of the statistical model. The PMF confidence interval was computed using Montecarlo simulations. For two case studies, it was possible to improve the estimated quantiles and the PMF, and it was possible to identify the advantage of using non systematic information.

RESUMEN En el marco del proyecto Balances Hidrológicos de Colombia se desarrollo HIDRO-SIG, un sistema de información geográfico (SIG) para la estimación, despliegue, análisis y consulta interactiva de las variables más importantes del ciclo hidrológico en Colombia, tales como precipitación, evaporación potencial y real y escorrentía, tanto a nivel anual como mensual. Es un SIG flexible y versátil para el

A long-term flood record from the Buffels River, the largest ephemeral river of NW South Africa (9250 km2), was reconstructed based on interpretation of palaeoflood, documentary and instrumental rainfall data. Palaeoflood data were obtained at three study reaches, with preserved sedimentary evidence indicating at least 25 large floods during the last 700 yr. Geochronological control for the palaeoflood record was provided by radiocarbon and optically stimulated luminescence (OSL) dating. Annual resolution was obtained since the 19th century using the overlapping documentary and instrumental records. Large floods coincided in the past within three main hydroclimatic settings: (1) periods of regular large flood occurrence (1 large flood/~30 yr) under wetter and cooler prevailing climatic conditions (AD 1600–1800), (2) decreasing occurrence of large floods (1 large flood/~100 yr) during warmer conditions (e.g., AD 1425–1600 and after 1925), and (3) periods of high frequency of large fl...

ABSTRACT The largest Kuiseb River floods initiate at the basin’s semi-arid headwater. Downstream, along the hyperarid Namib Desert, these floodwaters are feeding shallow alluvial aquifers, the only available water for human activity and for the natural ecology. Here, we characterize the largest floods and their changing frequency and magnitudes using palaeohydrological methods. Along 120 km of the rivers canyon 35 palaeoflood deposit sites were identified. At five of these sites we conducted stratigraphic and geochronological analyses and flood discharge estimations. The upper bound of the largest flood over the late Holocene is �1475 m3 s�1. Over the last 1300 years more than ten floods have exceeded 1250 m3 s�1. An additional 33 floods exceeded 400 m3 s�1. The last millennium was characterized by one large flood every 30–40 years during the periods 1250–1335, 1355– 1565 and 1715 AD to the present. A slight increase in flood frequency (not magnitude) occurred during 1565–1715 AD (one large flood in �20 years) and during two short episodes, 1185–1205 and 1335–1355 AD (seven and four floods in 20 years, respectively). These episodes of increased flood frequency are associated with other proxy records of higher water availability in the Namib

Three distribution functions with upper bound were used to estimate high return period flood-quantiles of Mediterranean rivers. The parameters of the EV4 (Extreme Value with four parameters), LN4 (Lognormal with four parameters) and TDF (Transformed ...