99 shared publications
Department of Civil Engineering: Hydraulics, Energy and Environment, Technical University of Madrid, Madrid, Spain
57 shared publications
Universidad Politécnica de Madrid; Madrid Spain
11 shared publications
Department of Artificial Intelligence, Universidad Politécnica de Madrid, Boadilla del Monte, Madrid, Spain
1 shared publications
Ministerio de Fomento
1 shared publications
Departamento de Informática, Universidad de Carlos III, Madrid, Spain
(1995 - 2018)
Hydrological dam safety assessment methods traditionally assume that the reservoir is full while it receives the design flood. In practice, reservoir management strategy determines the probability distribution of reservoir levels at the beginning of flood episodes. In this study we present a method to economically assess the influence of reservoir management strategy on hydrological dam safety and downstream flood risk. The method was applied to a gated-spillway dam located in the Tagus river basin. A set of 100000 inflow hydrographs was generated through a Monte Carlo procedure, reproducing the observed statistics of main hydrograph characteristics: peak flow, volume and duration. The set of 100000 hydrographs was routed through the reservoir applying the Volumetric Operation Method as flood control strategy. Three different scenarios were studied: initial reservoir level equal to maximum normal level, equal to a maximum conservation level and following the probability distribution of initial reservoir levels. In order to evaluate economically the influence of initial variable reservoir level and compare the three scenarios, a global risk index was applied. The index combines the hydrological risk for the dam, linked to the maximum water level experienced in the reservoir while the flood is routed, and the flood risk in the downstream river reach, linked to the discharge releases from the dam. The results highlighted the importance of considering the fluctuation of initial reservoir level for assessing the risk related to hydrological dam safety. Within the case study, the global risk index reduced its value up to 93 % if variable initial reservoir level is accounted, from 1445.6 x103 to 83 x103 euros.
The aims of this study are to quantify the effects of key properties of rainfall time series (frequency, duration, depth, rate and peak, time between events, length of series and precipitation thresholds, among others) on the hydrologic design of sustainable urban drainage systems (SuDS), to test a method for their estimation from daily time series and to quantify their uncertainty. Several typologies of SuDS infrastructures are designed to achieve a target treatment capacity. This target capacity is usually defined according to two methods: treating a percentage of the total volume of rainfall (50, 80, 90, 95, 99%) or treating a percentage of the total number of rainfall events (50, 80, 90, 95, 99%). We considered the city of Madrid as the case study, compiling 58 years of observed data (10-minute time step) and aggregating to daily time series. We obtained the design parameters from the full resolution dataset and then tested a simplified method to estimate them from daily time series of varying length. First, we calculated the design parameters for different storm thresholds (0, 1 and 2 millimeters). Second, we determined the design parameters from the aggregated daily time series by applying a temporal stochastic rainfall generator model (RainSimV3). We estimated the model parameters from daily data and generated 100 series of 58 years at 10-minute time step, and compared the results. Third, we generated 100 series of different lengths (20, 30, 40, 50, 58, 80 and 100 years). Fourth, we generated 100 series of 58 years at 10-minute time step (for each series length). Finally, we analyzed the uncertainty produced by the length of the observed data set. Results showed that, depending on the criteria adopted for the estimation of rainfall design parameters, SuDS structure volumes could vary up to 30 %. Further research includes the analysis of different climate locations.
We evaluate alternatives for the management of water for agriculture under climate change in six representative basins of Southern Europe: Duero-Douro, Ebro, Guadalquivir, Po, Maritsa-Evros and Struma. Management objective is maximizing water availability, understood as the maximum demand that can be satisfied with a given reliability. We focus on water availability for agriculture. For simplification we are assuming only two types of demands: urban and irrigation. Water is first allocated to urban demands following the established priority and the remaining resources are allocated to agriculture. If water availability is not enough to satisfy all irrigation demands, management measures are applied with the goal of achieving a balance between resources and demands. We present an analysis of three possible management measures to face water scarcity in the long term scenario: increasing reservoir storage, improving efficiency of urban water use and modifying water allocation to environmental flows. These management measures are globally evaluated for the selected basins in three representative climate scenarios, comparing their possible range and effectiveness. While in some basins, like Ebro or Struma, measures can significantly increase water availability and compensate for a fraction of water scarcity due to climate change, in other basins, like Guadalquivir, water availability cannot be enhanced with management measures and irrigation water use will have to be reduced.
Adequate design of energy dissipation structures is essential for effective flood control. Theoretical analysis of these structures is complex due to the turbulent nature of supercritical flow and is further complicated by air entrainment. The effect of aeration on water flow has been one of most analysed phenomena during the last decades due to its influence on the behaviour of hydraulic structures. The objective of this study is to characterize the influence of aeration on the boundary friction in supercritical conditions and fully turbulent flows. Our analysis is based on a physical model designed to reproduce these phenomena in the Hydraulics Laboratory of CEDEX (Spain), funded by a research project of the Spanish Ministry of Economy.
The structure consists of a spillway chute 6.5 m high, 0.5 m wide and slope of 75%, followed by a 10 m horizontal channel where the hydraulic jump is confined. Water and air are supplied by a pump and compressors and controlled at the entrance by several valves and flowmeters. This device has a pressurized intake, with 10 m head of additional pressure, which generates the mixture to reproduce different scenarios of emulsified flow, with rates up to 300 l/s of water and 3000 l/min of air. Under these conditions, velocity ranges from 6 to 12 m/s with Froude number between 4 and 11.
Currently, the channel is monitored to measure the velocity profile and air concentration in the flow. The aim of our research is to analyse the relation between air concentration and energy dissipation by friction, in order to link the air concentration rate to the Manning roughness number and other methods of friction quantification. This characterization is based on the velocity and concentration profiles along the vertical axis. We collected data of 12 different scenarios to analyse the relationship between aeration rate and roughness coefficient. We found that greater air entrainment implies acceleration of the flow. Since friction is the main energy dissipation mechanism in the chute, hydraulic structures should be designed to minimize air entrainment and thus enhance energy dissipation by friction.