Mapping of uplift hazard due to rising groundwater level during floods

Abstract

Abstract European Directive 2007/60/EC only briefly mentions the problem of hazard arising due to groundwater flooding, and techniques for the mapping of hazard occuring due to rising groundwater have not yet been scientifically developed. The groundwater‐related threats that occur during floods may include concentrated leakage of groundwater behind levees, heave, or potential uplift of the topsoil layer at the protected area. The hazard corresponding to rising groundwater level depends on a number of factors related to the flood course, groundwater regime, geology, and topology of the protected area. The limit state approach is applied to the assessment and mapping of hazard induced by rising groundwater level in the area behind flood protection barriers, and the contributing factors are discussed, quantified, and incorporated into the limit state condition for topsoil layer uplift (UPL). An over‐design factor is expressed as a function of the spatial co‐ordinates (x, y). Data from geological and hydrogeological surveys and groundwater flow modelling are used to evaluate individual terms in the limit state condition. Uncertainties in the input data are expressed via partial factors. Data collection and their geographic information systems analysis completed with hydraulic modelling are crucial techniques in the hazard mapping of potential UPL during floods. The article includes a case study featuring a flood protection scheme for a shopping centre in the city of Brno, Czech Republic.

Keywords

• European Directive 2007/60/EC
• flooding
• groundwater
• hazard mapping
• limit state
• uplift