3394 resultaten

  • Dynamic Adaptive Policy Pathways (DAPP)

    Auteurs: Haasnoot, M.; Warren, A.; Kwakkel, J.H. (2019)

    Dynamic Adaptive Policy Pathways (DAPP) is a DMDU approach that explicitly includes decision making over time. The essence is proactive and dynamic planning in response to how the future actually unfolds. DAPP explores alternative sequences of decisions (adaptation pathways) for multiple futures and illuminates the path dependency of alternative strategies. It opens the decision space and helps to overcome policy paralysis due to deep uncertainty. There are different routes that can achieve the objectives under changing conditions (like ‘different roads leading to Rome’). Policy actions have an uncertain design life and might fail sooner or later to continue achieving objectives as the operating conditions change (i.e. they reach an adaptation tipping point (ATP)). Similarly, opportunity tipping points may occur. Multiple pathways are typically visualized in a metro map or decision tree, with time or changing conditions on one of the axes. DAPP supports the design of a dynamic adaptive strategy that includes initial actions, long-term options, and adaptation signals to identify when to implement the long-term options or revisit decisions.

  • Dynamic Adaptive Policy Pathways (DAPP) : from theory to practice

    Auteurs: Lawrence, J.; Haasnoot, M.; McKim, L.; Atapattu, D.; Campbell, G.S.; Stroombergen, A. (2019)

    Decision making by flood risk managers is challenged by uncertainty and changing climate risk profiles that have elements of deep uncertainty. Flood risk managers at a regional level in New Zealand requested better understanding and tools for decision making under conditions of uncertainty and changing conditions. A game was used to catalyze a process of new knowledge transfer and its uptake in technical assessments and decision making processes. The understanding enabled DAPP to be used to develop a long-term plan that can accommodate changes in flood frequency from climate change (as projected in three climate change scenarios) over at least 100 years. Use of “new” economic tools with DAPP facilitated decision making to consider the sensitivity of alternative policies to a range of climate change scenarios, to discount rate, decision review date, and costs and losses, thus addressing deep uncertainty by considering the long-term effects of initial decisions to changing conditions. The risk of path-dependent decisions and the role that current frameworks and practices play in blinding actors to the range of possible outcomes that could evolve in the future, was reduced. A series of interventions to raise and increase awareness through new information and its framing, experimentation, and leadership enabled the uptake of DAPP.

  • Pan-European calculation of hydrologic stress metrics in rivers : a first assessment with potential connections to ecological status

    Auteurs: Panagopoulos, Y.; Stefanidis, K.; Faneca Sanchez, M.; Sperna Weiland, F.C.; Beek, R. van; Venohr, M.; Globevnik, L.; Mimikou, M; Birk, S. (2019)
    Gepubliceerd in: Water, volume 11 (2019) nummer 4, pagina 1-17

    The hydrologic regime of a river is one of the factors determining its ecological status. This paper tries to indicate the present hydrologic stress occurring across European rivers on the basis of model integration. This results in a pan-European assessment at the resolution of the functional elementary catchment (FEC), based on simulated daily time-series of river flows from the model PCR-GLOBWB. To estimate proxies of the present hydrologic stress, two datasets of river flow were simulated under the same climate, one from a hypothetic least disturbed condition scenario and the second from the anthropogenic scenario with the actual water management occurring. Indicators describing the rivers’ hydrologic regime were calculated with the indicators of hydrologic alteration (IHA) software package and the river total mean flow and the relative baseflow magnitude over the total flow were used to express the deviations between the two scenarios as proxy metrics of rivers’ hydrologic alteration or hydrologic stress. The alteration results on Europe’s FEC-level background showed that Southern Europe is more hydrologically stressed than the rest of Europe, with greater potential for hydrology to be clearly associated with river segments of unreached good ecological status and high basin management needs.

  • Investments under non-stationarity : economic evaluation of adaptation pathways

    Auteurs: Haasnoot, M.; Aalst, M.A. van; Rozenberg, J.; Dominique, K.; Matthews, J.; Bouwer, L.M.; Kind, J.; LeRoy Poff, N. (2019)
    Gepubliceerd in: Climatic change (2019), pagina 1-13

    Investment decisions about capital-intensive, long-lived infrastructure are challenging due to uncertainty about their future performance, particularly if the performance is sensitive to climate change. Such investments, like those made for water infrastructure, are rarely evaluated over their total operational lifetime, during which socio-economic and environmental changes can cause potential lock-ins and reduced options for future choices that lead to high costs to transfer to other options. We propose an economic evaluation framework to explore adaptation pathways, or sequences of strategic investments options, that can be implemented if needed due to changing conditions. A novel feature is the inclusion of “transfer costs” associated with a switch to alternative pathways to allow adaptive decision-making and to minimize the cost of adjustment over time. Implementing a pathway-driven approach represents a break with most institutional decision-making processes and can significantly improve decision-making under uncertainty compared to the conventional single-investment perspective. We present a case study on flood risk management in the Netherlands to show the longterm socio-economic consequences of short-term decisions by going beyond the project cycle horizon.

  • User guide to SUB-CR : a MODFLOW package for land subsidence and aquifer system compaction that includes creep

    Auteurs: Kooi, H.; Bakr, M.; Lange, G.J. de; Haan, E.J. den; Erkens, G. (2018)

    This document is the user guide of SUB-CR, version 1.0. SUB-CR is a MODFLOW-2005 based land subsidence package developed by Deltares1 that includes consolidation by creep. The package was developed to allow the modelling of land subsidence with a more comprehensive and more complete process representation of soft-sediment deformation than existing regional-scale hydrogeological models of land subsidence which do not consider creep. Creep and secondary consolidation are important in geotechnical applications involving soft-sediment (silt, clay, peat) consolidation. There is no obvious reason why creep would be irrelevant or insignificant when these sediments consolidate and cause land subsidence driven by groundwater use and groundwater management.

  • The benefits of spatial resolution increase in global simulations of the hydrological cycle evaluated for the Rhine and Mississippi basins

    Auteurs: Benedict, I.; Heerwaarden, C.C. van; Weerts, A.H.; Hazeleger, W. (2019)
    Gepubliceerd in: Hydrology and earth system sciences, volume 23 (2019) nummer 3, pagina 1779-1800

    To study the global hydrological cycle and its response to a changing climate, we rely on global climate models (GCMs) and global hydrological models (GHMs). The spatial resolution of these models is restricted by computational resources and therefore limits the processes and level of detail that can be resolved. Increase in computer power therefore permits increase in resolution, but it is an open question where this resolution is invested best: in the GCM or GHM. In this study, we evaluated the benefits of increased resolution, without modifying the representation of physical processes in the models. By doing so, we can evaluate the benefits of resolution alone. We assess and compare the benefits of an increased resolution for a GCM and a GHM for two basins with long observational records: the Rhine and Mississippi basins. Increasing the resolution of a GCM (1.125 to 0.25) results in an improved precipitation budget over the Rhine basin, attributed to a more realistic large-scale circulation. These improvements with increased resolution are not found for the Mississippi basin, possibly because precipitation is strongly dependent on the representation of still unresolved convective processes. Increasing the resolution of the GCM improved the simulations of the monthly-averaged discharge for the Rhine, but did not improve the representation of extreme streamflow events. For the Mississippi basin, no substantial differences in precipitation and discharge were found with the higher-resolution GCM and GHM. Increasing the resolution of parameters describing vegetation and orography in the high-resolution GHM (from 0.5 to 0.05) shows no significant differences in discharge for both basins. A straightforward resolution increase in the GHM is thus most likely not the best method to improve discharge predictions, which emphasizes the need for better representation of processes and improved parameterizations that go hand in hand with resolution increase in a GHM.

  • Morphological development after the July 2014 flow slide on the tidal flat of Walsoorden in the Western Scheldt

    Auteur: Schaick, S.J. van (2015)

    A large flow slide occurred at the tidal flat of Walsoorden in July 2014. A flow slide occurs when the slope is sufficient steep and a trigger starts the process of liquefaction or breaching. A measurement campaign was initiated to measure the bathymetry around the tidal flat, starting a few months before the flow slide. After the event monthly measurements were taken to monitor the development of the area. Based on the bathymetry measurements, the volume changes in the channel and in the gap were determined. An existing Delft3D model schematisation of the Western Scheldt was used to calculate the morphological development. The model was setup around the tidal flat of Walsoorden. The morphological changes determined by the model are different from the bathymetric changes found in the measurements. In the model the sediment accretion smoothens out; the sediment is deposited on the sides of the accumulation. Most of the sediment from the channel is transported in ebb direction. The model shows almost no sedimentation in the gap, which is contradictive with the measurements. The sensitivity of the model was tested to investigate the differences between the observations and the model.

  • Operationalizing socio-economic and climate tipping points

    Auteurs: Ginkel, C.H. van; Jeuken, A.B.M.; Haasnoot, M. (2018)

    The objective of this deliverable is to operationalize the concept of tipping points within COACCH. Tipping points are an important notion in climate change research and communication. Tipping of large elements of the climate system may cause rapid change in the biophysical system (e.g. accelerated sea level rise) which has profound consequences for the socio-economic structure of Europe. However, also gradual changes in climatic conditions may significantly and abruptly alter socio-economic structures in Europe. COACCH therefore set out to significantly advance the knowledge on climate tipping elements and socio-economic tipping points induced by climate change.

  • Climate change induced salinization of drinking water inlets along a tidal branch of the Rhine River : impact assessment and an adaptive strategy for water resources management

    Auteurs: Brink, M.A. van den; Huismans, Y.; Blaas, M.; Zwolsman, G. (2019)
    Gepubliceerd in: Climate, volume 7 (2019) nummer 4, pagina 1-14

    This study presents the results of an impact analysis of climate change on salinization and the long-term availability of drinking water resources along the river Lek, a tidal branch of the Rhine delta, and a potential mitigation measure. To this end, a one-dimensional modelling approach was used that enabled studying 50 years of variation in discharge and tide in current and future climate. It was found that all locations are increasingly vulnerable to salt intrusion caused by the combination of sea level rise and decreasing river discharges. This affects both the yearly average chloride concentration and long duration exceedances of the threshold value of 150 mg/L. It was also found that diverting a higher fresh water discharge to the Lek of several tens of cubic meters per second reduces the risk of salinization at the upstream inlet locations. However, the increased influence of seawater intrusion on the drinking water inlets cannot be fully compensated for by this measure. The potential gain of the extra water for the drinking water inlets along the Lek has to be balanced against the impact of this measure on water levels and stream flows in other parts of the river system.

  • Morfologisch advies broedeilanden : veiligstellen De Bol

    Auteurs: Schrijvershof, R.A.; Röbke, B.R. (2019)

    Dit rapport beschrijft een verkennende morfologische studie naar de aanleg van een zandsuppletie ter bescherming (versterking) van het bestaande broedeiland De Bol op het plaatcomplex Hooge Platen (Westerschelde). De doelstelling van de suppletie is het broedareaal op De Bol veiligstellen.

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