TY - JOUR A1 - Vormoor, Klaus Josef A1 - Lawrence, Deborah A1 - Schlichting, Lena A1 - Wilson, Donna A1 - Wong, Wai Kwok T1 - Evidence for changes in the magnitude and frequency of observed rainfall vs. snowmelt driven floods in Norway JF - Journal of hydrology N2 - There is increasing evidence for recent changes in the intensity and frequency of heavy precipitation and in the number of days with snow cover in many parts of Norway. The question arises as to whether these changes are also discernable with respect to their impacts on the magnitude and frequency of flooding and on the processes producing high flows. In this study, we tested up to 211 catchments for trends in peak flow discharge series by applying the Mann-Kendall test and Poisson regression for three different time periods (1962-2012, 1972-2012, 1982-2012). Field-significance was tested using a bootstrap approach. Over threshold discharge events were classified into rainfall vs. snowmelt dominated floods, based on a simple water balance approach utilizing a nationwide 1 x 1 km(2) gridded data set with daily observed rainfall and simulated snowmelt data. Results suggest that trends in flood frequency are more pronounced than trends in flood magnitude and are more spatially consistent with observed changes in the hydrometeorological drivers. Increasing flood frequencies in southern and western Norway are mainly due to positive trends in the frequency of rainfall dominated events, while decreasing flood frequencies in northern Norway are mainly the result of negative trends in the frequency of snowmelt dominated floods. Negative trends in flood magnitude are found more often than positive trends, and the regional patterns of significant trends reflect differences in the flood generating processes (FGPs). The results illustrate the benefit of distinguishing FGPs rather than simply applying seasonal analyses. The results further suggest that rainfall has generally gained an increasing importance for the generation of floods in Norway, while the role of snowmelt has been decreasing and the timing of snowmelt dominated floods has become earlier. (C) 2016 Elsevier B.V. All rights reserved. KW - Peak flow trends KW - Peak-over-threshold KW - Flood generating processes KW - Rainfall floods KW - Snowmelt floods KW - Climate change Y1 - 2016 U6 - https://doi.org/10.1016/j.jhydrol.2016.03.066 SN - 0022-1694 SN - 1879-2707 VL - 538 SP - 33 EP - 48 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Vormoor, Klaus Josef A1 - Heistermann, Maik A1 - Bronstert, Axel A1 - Lawrence, Deborah T1 - Hydrological model parameter (in)stability BT - "crash testing" the HBV model under contrasting flood seasonality conditions JF - Hydrological sciences journal = Journal des sciences hydrologiques N2 - This paper investigates the transferability of calibrated HBV model parameters under stable and contrasting conditions in terms of flood seasonality and flood generating processes (FGP) in five Norwegian catchments with mixed snowmelt/rainfall regimes. We apply a series of generalized (differential) split-sample tests using a 6-year moving window over (i) the entire runoff observation periods, and (ii) two subsets of runoff observations distinguished by the seasonal occurrence of annual maximum floods during either spring or autumn. The results indicate a general model performance loss due to the transfer of calibrated parameters to independent validation periods of -5 to -17%, on average. However, there is no indication that contrasting flood seasonality exacerbates performance losses, which contradicts the assumption that optimized parameter sets for snowmelt-dominated floods (during spring) perform particularly poorly on validation periods with rainfall-dominated floods (during autumn) and vice versa. KW - hydrological modelling KW - flood seasonality KW - differential split-sample test KW - flood generating processes KW - Nordic catchments Y1 - 2018 U6 - https://doi.org/10.1080/02626667.2018.1466056 SN - 0262-6667 SN - 2150-3435 VL - 63 IS - 7 SP - 991 EP - 1007 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - GEN A1 - Vormoor, Klaus Josef A1 - Heistermann, Maik A1 - Bronstert, Axel A1 - Lawrence, Deborah T1 - Hydrological model parameter (in)stability BT - “crash testing” the HBV model under contrasting flood seasonality conditions T2 - Hydrological Sciences Journal N2 - This paper investigates the transferability of calibrated HBV model parameters under stable and contrasting conditions in terms of flood seasonality and flood generating processes (FGP) in five Norwegian catchments with mixed snowmelt/rainfall regimes. We apply a series of generalized (differential) split-sample tests using a 6-year moving window over (i) the entire runoff observation periods, and (ii) two subsets of runoff observations distinguished by the seasonal occurrence of annual maximum floods during either spring or autumn. The results indicate a general model performance loss due to the transfer of calibrated parameters to independent validation periods of −5 to −17%, on average. However, there is no indication that contrasting flood seasonality exacerbates performance losses, which contradicts the assumption that optimized parameter sets for snowmelt-dominated floods (during spring) perform particularly poorly on validation periods with rainfall-dominated floods (during autumn) and vice versa. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 459 KW - hydrological modelling KW - flood seasonality KW - differential split-sample test KW - flood generating processes KW - Nordic catchments Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-413008 ER - TY - JOUR A1 - Hundecha, Yeshewatesfa A1 - Sunyer, Maria A. A1 - Lawrence, Deborah A1 - Madsen, Henrik A1 - Willems, Patrick A1 - Bürger, Gerd A1 - Kriauciuniene, Jurate A1 - Loukas, Athanasios A1 - Martinkova, Marta A1 - Osuch, Marzena A1 - Vasiliades, Lampros A1 - von Christierson, Birgitte A1 - Vormoor, Klaus Josef A1 - Yuecel, Ismail T1 - Inter-comparison of statistical downscaling methods for projection of extreme flow indices across Europe JF - Journal of hydrology N2 - The effect of methods of statistical downscaling of daily precipitation on changes in extreme flow indices under a plausible future climate change scenario was investigated in 11 catchments selected from 9 countries in different parts of Europe. The catchments vary from 67 to 6171 km(2) in size and cover different climate zones. 15 regional climate model outputs and 8 different statistical downscaling methods, which are broadly categorized as change factor and bias correction based methods, were used for the comparative analyses. Different hydrological models were implemented in different catchments to simulate daily runoff. A set of flood indices were derived from daily flows and their changes have been evaluated by comparing their values derived from simulations corresponding to the current and future climate. Most of the implemented downscaling methods project an increase in the extreme flow indices in most of the catchments. The catchments where the extremes are expected to increase have a rainfall dominated flood regime. In these catchments, the downscaling methods also project an increase in the extreme precipitation in the seasons when the extreme flows occur. In catchments where the flooding is mainly caused by spring/summer snowmelt, the downscaling methods project a decrease in the extreme flows in three of the four catchments considered. A major portion of the variability in the projected changes in the extreme flow indices is attributable to the variability of the climate model ensemble, although the statistical downscaling methods contribute 35-60% of the total variance. (C) 2016 Elsevier B.V. All rights reserved. KW - Flooding KW - Statistical downscaling KW - Regional climate models KW - Climate change KW - Europe Y1 - 2016 U6 - https://doi.org/10.1016/j.jhydrol.2016.08.033 SN - 0022-1694 SN - 1879-2707 VL - 541 SP - 1273 EP - 1286 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Roe, Stephanie A1 - Streck, Charlotte A1 - Beach, Robert A1 - Busch, Jonah A1 - Chapman, Melissa A1 - Daioglou, Vassilis A1 - Deppermann, Andre A1 - Doelman, Jonathan A1 - Emmet-Booth, Jeremy A1 - Engelmann, Jens A1 - Fricko, Oliver A1 - Frischmann, Chad A1 - Funk, Jason A1 - Grassi, Giacomo A1 - Griscom, Bronson A1 - Havlik, Petr A1 - Hanssen, Steef A1 - Humpenöder, Florian A1 - Landholm, David A1 - Lomax, Guy A1 - Lehmann, Johannes A1 - Mesnildrey, Leah A1 - Nabuurs, Gert-Jan A1 - Popp, Alexander A1 - Rivard, Charlotte A1 - Sanderman, Jonathan A1 - Sohngen, Brent A1 - Smith, Pete A1 - Stehfest, Elke A1 - Woolf, Dominic A1 - Lawrence, Deborah T1 - Land-based measures to mitigate climate change BT - potential and feasibility by country JF - Global change biology N2 - Land-based climate mitigation measures have gained significant attention and importance in public and private sector climate policies. Building on previous studies, we refine and update the mitigation potentials for 20 land-based measures in >200 countries and five regions, comparing “bottom-up” sectoral estimates with integrated assessment models (IAMs). We also assess implementation feasibility at the country level. Cost-effective (available up to $100/tCO2eq) land-based mitigation is 8–13.8 GtCO2eq yr−1 between 2020 and 2050, with the bottom end of this range representing the IAM median and the upper end representing the sectoral estimate. The cost-effective sectoral estimate is about 40% of available technical potential and is in line with achieving a 1.5°C pathway in 2050. Compared to technical potentials, cost-effective estimates represent a more realistic and actionable target for policy. The cost-effective potential is approximately 50% from forests and other ecosystems, 35% from agriculture, and 15% from demand-side measures. The potential varies sixfold across the five regions assessed (0.75–4.8 GtCO2eq yr−1) and the top 15 countries account for about 60% of the global potential. Protection of forests and other ecosystems and demand-side measures present particularly high mitigation efficiency, high provision of co-benefits, and relatively lower costs. The feasibility assessment suggests that governance, economic investment, and socio-cultural conditions influence the likelihood that land-based mitigation potentials are realized. A substantial portion of potential (80%) is in developing countries and LDCs, where feasibility barriers are of greatest concern. Assisting countries to overcome barriers may result in significant quantities of near-term, low-cost mitigation while locally achieving important climate adaptation and development benefits. Opportunities among countries vary widely depending on types of land-based measures available, their potential co-benefits and risks, and their feasibility. Enhanced investments and country-specific plans that accommodate this complexity are urgently needed to realize the large global potential from improved land stewardship. KW - AFOLU KW - co-benefits KW - demand management KW - feasibility KW - land management KW - land sector KW - mitigation KW - natural climate solutions KW - nature-based solutions Y1 - 2021 U6 - https://doi.org/10.1111/gcb.15873 SN - 1365-2486 VL - 27 IS - 23 SP - 6025 EP - 6058 PB - Wiley-Blackwell CY - Oxford ER -