TY  - JOUR
A1  - Seibert, Mathias
A1  - Merz, Bruno
A1  - Apel, Heiko
T1  - Seasonal forecasting of hydrological drought in the Limpopo Basin
BT  - a comparison of statistical methods
JF  - Hydrology and earth system sciences : HESS
N2  - The Limpopo Basin in southern Africa is prone to droughts which affect the livelihood of millions of people in South Africa, Botswana, Zimbabwe and Mozambique. Seasonal drought early warning is thus vital for the whole region. In this study, the predictability of hydrological droughts during the main runoff period from December to May is assessed using statistical approaches. Three methods (multiple linear models, artificial neural networks, random forest regression trees) are compared in terms of their ability to forecast streamflow with up to 12 months of lead time. The following four main findings result from the study. 1. There are stations in the basin at which standardised streamflow is predictable with lead times up to 12 months. The results show high inter-station differences of forecast skill but reach a coefficient of determination as high as 0.73 (cross validated). 2. A large range of potential predictors is considered in this study, comprising well-established climate indices, customised teleconnection indices derived from sea surface temperatures and antecedent streamflow as a proxy of catchment conditions. El Nino and customised indices, representing sea surface temperature in the Atlantic and Indian oceans, prove to be important teleconnection predictors for the region. Antecedent streamflow is a strong predictor in small catchments (with median 42% explained variance), whereas teleconnections exert a stronger influence in large catchments. 3. Multiple linear models show the best forecast skill in this study and the greatest robustness compared to artificial neural networks and random forest regression trees, despite their capabilities to represent nonlinear relationships. 4. Employed in early warning, the models can be used to forecast a specific drought level. Even if the coefficient of determination is low, the forecast models have a skill better than a climatological forecast, which is shown by analysis of receiver operating characteristics (ROCs). Seasonal statistical forecasts in the Limpopo show promising results, and thus it is recommended to employ them as complementary to existing forecasts in order to strengthen preparedness for droughts.
Y1  - 2017
U6  - https://doi.org/10.5194/hess-21-1611-2017
SN  - 1027-5606
SN  - 1607-7938
VL  - 21
SP  - 1611
EP  - 1629
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Kreibich, Heidi
A1  - Di Baldassarre, Giuliano
A1  - Vorogushyn, Sergiy
A1  - Aerts, Jeroen C. J. H.
A1  - Apel, Heiko
A1  - Aronica, Giuseppe T.
A1  - Arnbjerg-Nielsen, Karsten
A1  - Bouwer, Laurens M.
A1  - Bubeck, Philip
A1  - Caloiero, Tommaso
A1  - Chinh, Do T.
A1  - Cortes, Maria
A1  - Gain, Animesh K.
A1  - Giampa, Vincenzo
A1  - Kuhlicke, Christian
A1  - Kundzewicz, Zbigniew W.
A1  - Llasat, Maria Carmen
A1  - Mard, Johanna
A1  - Matczak, Piotr
A1  - Mazzoleni, Maurizio
A1  - Molinari, Daniela
A1  - Dung, Nguyen V.
A1  - Petrucci, Olga
A1  - Schröter, Kai
A1  - Slager, Kymo
A1  - Thieken, Annegret
A1  - Ward, Philip J.
A1  - Merz, Bruno
T1  - Adaptation to flood risk
BT  - Results of international paired flood event studies
JF  - Earth's Future
N2  - As flood impacts are increasing in large parts of the world, understanding the primary drivers of changes in risk is essential for effective adaptation. To gain more knowledge on the basis of empirical case studies, we analyze eight paired floods, that is, consecutive flood events that occurred in the same region, with the second flood causing significantly lower damage. These success stories of risk reduction were selected across different socioeconomic and hydro-climatic contexts. The potential of societies to adapt is uncovered by describing triggered societal changes, as well as formal measures and spontaneous processes that reduced flood risk. This novel approach has the potential to build the basis for an international data collection and analysis effort to better understand and attribute changes in risk due to hydrological extremes in the framework of the IAHSs Panta Rhei initiative. Across all case studies, we find that lower damage caused by the second event was mainly due to significant reductions in vulnerability, for example, via raised risk awareness, preparedness, and improvements of organizational emergency management. Thus, vulnerability reduction plays an essential role for successful adaptation. Our work shows that there is a high potential to adapt, but there remains the challenge to stimulate measures that reduce vulnerability and risk in periods in which extreme events do not occur.
KW  - flooding
KW  - vulnerability
KW  - global environmental change
KW  - adaptation
Y1  - 2017
U6  - https://doi.org/10.1002/2017EF000606
SN  - 2328-4277
VL  - 5
SP  - 953
EP  - 965
PB  - Wiley
CY  - Hoboken
ER  -