The accuracy and quality of river forecasts are dependent on the nature of each flood. Less extreme , more common, floods may afford deviations between the predicted forecast and observed stage because the locals may be prepared, based on past experience to deal with the less extreme flood events. For less frequent, high flow events the flood forecasts and advanced warning time are more critical, because the locals need time to develop emergency response plans. The National Weather Service River Forecast Centers (NWS RFC) develop the river forecasts and provide them to the National Weather Service Weather Forecast Office (NWS WFO) for dissemination. During flood events the RFC's are tasked with processing the observed data and running, reviewing and modifying the forecast models to provide reasonable river forecasts based on observed conditions and the forecasters' experience. This thesis will discuss the personal experiences of the author, analyze the components of the National Weather Service river forecasting process, analyze June 2008 river and precipitation forecasts for several eastern Iowa watersheds, and discuss the results of the analysis as well as provide support to current calls to action to support forecast verification through the hindcasting process.

Face à l’érosion globale de la biodiversité des écosystèmes aquatiques continentaux, l’identification des mesures de gestion les plus urgentes à mettre en place est cruciale. En s’appuyant sur une approche innovante et multi-facettes de la diversité, les priorités de conservation pour les assemblages de poissons de rivière ont pu être déterminées à l’échelle de la France. La durabilité de ces priorités de conservation face aux principales composantes des changements globaux a ensuite été évaluée afin d’identifier les zones qui protégeront efficacement la biodiversité actuelle dans le futur. La méthodologie développée a finalement été appliquée au réseau hydrographique du département du Pas-de-Calais dans le but d’identifier précisément les priorités locales de conservation et de restauration. Ces outils pourront par la suite être utilisés comme support d’aide à la décision et adaptés selon les besoins des gestionnaires des milieux aquatiques. / The global loss of biodiversity affects freshwater ecosystems, making it crucial to identify the priority management actions in order to protect freshwater biodiversity in an effective and sustainable way. Based on an innovative multi-faceted framework of diversity, the spatial priorities for the conservation of stream fish assemblages have been identified at the scale of France. Their robustness to several drivers of global changes has then been assessed to identify the areas that are likely to efficiently protect the present-day biodiversity in the future. The methodological framework proposed herein has finally been applied to the river network of the Pas-de-Calais department located in northern France to accurately identify the local conservation and restoration priorities. These management tools can be used to support the establishment of management actions in accordance with the needs of the local environmental decision-makers.

In this study, a numerical model is developed to determine shoreline changes due to wind wave induced longshore sediment transport, by solving sediment continuity equation and taking one line theory as a base, in existence of seawalls, groins, T-groins, offshore breakwaters and beach nourishment projects, whose dimensions and locations may be given arbitrarily. The model computes the transformation of deep water wave characteristics up to the surf zone and eventually gives the result of shoreline changes with user-friendly visual outputs. A method of representative wave input as annual average wave characteristics is presented. Compatibility of the currently developed tool is tested by a case study and it is shown that the results, obtained from the model, are in good agreement qualitatively with field measurements. In the scope of this study, input manner of long term annual wave data into model in miscellaneous ways is also discussed.

New decline curve models have been developed to overcome the boundary-dominated flow assumption of the basic Arps’ models, which restricts their application in ultra-low permeability reservoirs exhibiting long-duration transient flow regimes. However, these new decline curve analysis (DCA) methods are still based only on production rate data, relying on the assumption of stable flowing pressure. Since this stabilized state is not reached rapidly in most cases, the applicability of these methods and the reliability of their solutions may be compromised. In addition, production performance predictions cannot be disassociated from the existing operation constraints under which production history was developed. On the other hand, DCA is often carried out without a proper identification of flow regimes. The arbitrary application of DCA models regardless of existing flow regimes may produce unrealistic production forecasts, because these models have been designed assuming specific flow regimes. The main purpose of this study was to evaluate the possible benefits provided by including flowing pressures in production decline analysis. As a result, it have been demonstrated that decline curve analysis based on pressure-normalized rates can be used as a reliable production forecasting technique suited to interpret unconventional wells in specific situations such as unstable operating conditions, limited availability of production data (short production history) and high-pressure, rate-restricted wells. In addition, pressure-normalized DCA techniques proved to have the special ability of dissociating the estimation of future production performance from the existing operation constraints under which production history was developed. On the other hand, it was also observed than more consistent and representative flow regime interpretations may be obtained as diagnostic plots are improved by including MBT, pseudovariables (for gas wells) and pressure-normalized rates. This means that misinterpretations may occur if diagnostic plots are not applied correctly. In general, an improved forecasting ability implies greater accuracy in the production performance forecasts and more reliable reserve estimations. The petroleum industry may become more confident in reserves estimates, which are the basis for the design of development plans, investment decisions, and valuation of companies’ assets.