Hydrological Forecasting With Radar And The Probability Distributed Hydrological Model Pdm
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Hydrological Forecasting with Radar and the Probability Distributed Hydrological Model (PDM)
Author: Gbotemi Abraham Adediran
language: en
Publisher: Universal-Publishers
Release Date: 2015-07-01
The efficiency of a probabilistic hydrological forecasting system with weather radar and the Probability distributed hydrological model (PDM) was evaluated at the Brue catchment; south-western England. The ability of the radar to measure gauged precipitation in 2007 (regarded as the ground truth) was evaluated using Normalized Bias (NB) and Normalized Error (NE) statistics as the objective function of evaluation. The radar overestimated precipitation measurements by average gauges with NB value of 0.41 and a considerably low NE of 0.68. Furthermore, the effectiveness of a Deterministic nowcasting system (DNS) to forecast radar measured precipitation at 132 forecast time series of 6hrs forecast lead time was assessed. The DNS overestimated the radar measured precipitation with a NB value of 87% and recorded an accumulated NE of 146%. Moreover, the efficiencies of 10 ensemble precipitation forecats generated from a Stochastic nowcasting system (SNS) over the singular deterministic forecasts from the DNS was evaluated at 3 major hydrological events. Some of the ensembles significantly performed better than the deterministic forecast and brilliantly captured the radar measured precipitation at most of the forecast time series. Furthermore, the efficiencies of these sources of precipitation measurement to simulate flows with the PDM at the Brue catchment were also assessed by integrating the radar-based forecasts with measurements from average gauges. The PDM performed satisfactorily well in simulating the flows of 17th January 2007 with an average Nash–Sutcliffe Efficiency Index (NSE) of 0.65 and the model was judged insensitive to the significantly high precipitation inputs for the hydrological event of 27th of May 2007. However, the PDM performed poorly in simulating flows for the historical storms of 20th of July 2007; with the model under estimating flows with bias value of over 250 cumecs for an event popular for its devastating flooding in the Southwest of England. The model inadequacies was however associated to poor radar precipitation measurements and forecasts on which flow simulation was based. This work therefore emphasis the need for developments in hydrological modeling as well as advancement in weather radar technology to effectively correct radar errors due to radar calibration, signal attenuation, clutter and anomalous propagation, vertical variation of reflectivity, range effects, Z-R relationships, variations of drop size distributions, vertical air motions, beam overshooting the shallow precipitation and sampling issues, that has been identified to affect radar measurements.
Floods and Landslides: Integrated Risk Assessment
Author: Riccardo Casale
language: en
Publisher: Springer Science & Business Media
Release Date: 2012-12-06
Scientific reserach on natural disasters is now implementing new methodologies and aproaches as consequences of: 1. mutating impact of extreme natural events in response to societal change like land use, lifelines, communications, transportation, etc.; 2. development which claim for new urban and industrial territories, often in hazard prone areas; 3. impact of modern society on natural climate variability (climate change) and con sequently, on spatial and temporal frequency of extreme events related to hydro logical cycle. As consequence of the above mentioned items it is necessary to develop a global approach to territory in order to understand reciprocous influence between climate dynamics with their extreme consequences like floods and landslides and socio-eco nomic development. In such a way, and in response to societal change, scientific re search on floods and landslides is beginning to loose the classical mono disciplinary approach and it is starting to be a science of the hydrological processes. The course on "Floods and Landslides: integrated risk assessment" held in Orvieto (Italy) 19-26 may 1996, has been organised by the European Commission specifically with the aim of transferring to young European scientists these new views, in order to contribute to a future scientific community, capable to face with the future environ mental problems.
Hydrological Modelling in Arid and Semi-Arid Areas
Author: Howard Wheater
language: en
Publisher: Cambridge University Press
Release Date: 2007-11-22
Arid and semi-arid regions are defined as areas where water is at its most scarce. The hydrological regime in these areas is extreme and highly variable, and they face great pressures to deliver and manage freshwater resources. However, there is no guidance on the decision support tools that are needed to underpin flood and water resource management in arid areas. UNESCO initiated the Global network for Water and Development Information for arid lands (GWADI), and arranged a workshop of the world's leading experts to discuss these issues. This book presents chapters from contributors to the workshop, and includes case studies from the world's major arid regions to demonstrate model applications, and web links to tutorials and state-of-the-art modelling software. This volume is a valuable reference for researchers and engineers working on the water resources of arid and semi-arid regions.