Bat algorithm for dam–reservoir operation

Optimizing reservoir operation rule is considered as a complex engineering problem which requires an efficient algorithm to solve. During the past decade, several optimization algorithms have been applied to solve complex engineering problems, which water resource decision-makers can employ to optimize reservoir operation. This study investigates one of the new optimization algorithms, namely, Bat Algorithm (BA). The BA is incorporated with different rule curves, including first-, second-, and third-order rule curves. Two case studies, Aydoughmoush dam and Karoun 4 dam in Iran, are considered to evaluate the performance of the algorithm. The main purpose of the Aydoughmoush dam is to supply water for irrigation. Hence, the objective function for the optimization model is to minimize irrigation deficit. On the other hand, Karoun 4 dam is designed for hydropower generation. Three different evaluation indices, namely, reliability, resilience, and vulnerability were considered to examine the performance of the algorithm. Results showed that the bat algorithm with third-order rule curve converged to the minimum objective function for both case studies and achieved the highest values of reliability index and resiliency index and the lowest value of the vulnerability index. Hence, the bat algorithm with third-order rule curve can be considered as an appropriate optimization model for reservoir operation.     

Use of incremental analysis updates in 4D-Var data assimilation

The four-dimensional variational(4D-Var) data assimilation systems used in most operational and research centers use initial condition increments as control variables and adjust initial increments to find optimal analysis solutions. This approach may sometimes create discontinuities in analysis fields and produce undesirable spin ups and spin downs. This study explores using incremental analysis updates(IAU) in 4D-Var to reduce the analysis discontinuities. IAU-based 4D-Var has almost the same mathematical formula as conventional 4D-Var if the initial condition increments are replaced with time-integrated increments as control variables.The IAU technique was implemented in the NASA/GSFC 4D-Var prototype and compared against a control run without IAU. The results showed that the initial precipitation spikes were removed and that other discontinuities were also reduced,especially for the analysis of surface temperature.     

Soil erosion modeling of watershed using cubic,quadratic and quintic splines

Natural Hazards - Soil erosion is widespread with spatio-temporal variability and is central to the determination of sediment yield, which is vital to proper management of watersheds. We propose a...     

Evaluation of the prediction capability of AHP and F-AHP methods in flood susceptibility mapping of Ernakulam district (India)

Natural Hazards - Floods are one of the frequent natural hazards occurring in Kerala because of the remarkably high annual rate of rainfall. The objective of this study is to prepare the flood...     

Evaluation of the Hurricane Weather Research and Forecasting (HWRF) model for tropical cyclone forecasts over the North Indian Ocean (NIO)

Natural Hazards - The Hurricane Weather Research and Forecast (HWRF) model, which was operational at the US National Centers for Environmental Prediction, was ported in India Meteorological...     

Comparison of simple runoff models used in Korea for small watersheds

This study analysed runoff characteristics for three small watersheds in the Su‐Young River basin in Korea using the storage function method, the linear reservoir cascade model, and the discrete linear input–output model. The models performed well for the watersheds. The runoff analysis of the observed flood events showed that the storage function method was the most accurate of the three, and was followed by the linear reservoir cascade model and the discrete linear input–output model. Copyright © 1999 John Wiley & Sons, Ltd.     

An investigation of snowmelt runoff on experimental plots in Lulea,Sweden

Empirical characteristics of snowmelt runoff are derived from observations made during snowmelt in a six‐year period from 1980 to 1985 on three experimental plots and three plates located on the campus of the Lulea University of Technology in Lulea, Sweden. The plots had asphalt, gravel and grass surfaces. The plates were of different designs with one having the bottom cut out so that it was more like a frame. With the assumption that the asphalt surface of the plots was impervious, infiltration of meltwater into gravel and grass surfaces was deduced. Unlike rainfall infiltration, the graph of snowmelt infiltration rate resembled a flow hydrograph, with a distinct rise, a peak and a distinct recession. A strong linear relationship between the snowmelt runoff hydrograph peak and the snowmelt amount was found, which explained more than 90% of the variability in the snowmelt peak. This is in contrast with rainfall runoff where the relationship between runoff peak and volume is decidedly non‐linear. Hourly snowmelt runoff peak and daily snowmelt amount were found to exhibit nearly constant skew and follow approximately a Gumbel frequency distribution. Copyright © 2000 John Wiley & Sons, Ltd.     

Petrogenesis of S-type Ladakh granite and mafic microgranular enclaves in the southern margin of Ladakh batholith: An evidence of crust–mantle interaction during the collision between Indian and Eurasian plates

The previous studies revealed the I-type Ladakh magmatism in the Andean-type southern margin of the Ladakh batholith (LB) was related to the subduction of the Neotethyan Ocean and India-Eurasia collision. However, LB's S-type granitic magmatism and associated mafic microgranular enclaves (MMEs) are poorly constrained. Here, we present the new data for S-type Ladakh granite (LG) and associated monzodiorite MMEs in the Andean-type orogeny in the southern margin of the Eurasian plate. The low SiO₂ (47.4–53.9 wt%), high K₂O (1.56–3.21 wt%), Mg^# (52–65), continental-arc tracer patterns, and slightly depleted to evolved Sr-Nd isotopic composition ((⁸⁷Sr/⁸⁶Sr)i = 0.7047–0.7166; ℇ_Nd (t = 50 Ma) = (+1.40 to −8.92)) for MME suggest that they were derived from the phlogopite-bearing deep lithospheric mantle-source at a depth of 5.4–10.5 km depth with 810–870°C, 1.4–2.8 kbar, and enriched by sediment-melts addition into the mantle-wedge from subducting Neotethyan Oceanic slab. The mantle-derived ascending hot mafic magma mixing with felsic magma of the ancient northern Indian margin-derived, generates monzodiorite MME by assimilation and magma mixing processes. Plagioclase, amphibole, and biotite chemistry support the magma mixing processes. LG are characterized by high SiO₂ (63.4–75.0 wt%), K₂O (3.93–5.67 wt%), CaO/Na₂O ratio of >0.3, differentiation index (90.27–97.46), normative corundum (1.0–2.8), A/CNK values (1.00–1.18), hypersthene (0.7–5.7), and low Al₂O₃, MgO, TiO₂, Fe₂O₃. They also exhibit peraluminous, variable tracer elemental abundances, variable (⁸⁷Sr/⁸⁶Sr)i ratios (0.6967–0.7191), and high whole rock ℇ_Nd (t = 50 Ma) values of −4.15 to −11.92) and ancient two-stage Nd model age of 1160 and 1858 Ma. These features suggest that S-type Ladakh granites were derived from the melting of ancient metagreywacke-dominated metasedimentary rocks of the northern Indian margin by a large amount of mafic magma underplating after subducted Neotethyan slab-rollback. The formation of LG and MMEs related to the Andean-type orogeny in the southern margin of the Eurasian plate.     

Meteorological study of the first observation of red sprites from Poland

The first red sprite events scientifically observed from Poland on 20/21 July 2007, during the two-week SPARTAN Sprite-Watch 2007 campaign, are analysed in the context of the meteorological conditions over Poland and the Czech Republic at that time. The phenomena were detected and recorded from the IMWM High-Mountain Meteorological Observatory at Mount Śnieżka using a low-light television CCD camera. Meteorological conditions over the south-west Poland were monitored on the basis of information from the Polish and Czech meteorological radar and lightning detection systems and also from satellite infra-red difference images, indicating the development of thunderstorm clouds over central Europe. Four sprite events detected in the night-time of 20/21 July indicate that in this region sprites are produced by massive storm cells built on warm fronts which are supplied by warm and humid tropical air masses during local summer thunderstorm season.     

Dissecting the effect of rainfall variability on the statistical structure of peak flows

This study examines the role of rainfall variability on the spatial scaling structure of peak flows using the Whitewater River basin in Kansas as an illustration. Specifically, we investigate the effect of rainfall on the scatter, the scale break and the power law (peak flows vs. upstream areas) regression exponent. We illustrate why considering individual hydrographs at the outlet of a basin can lead to misleading interpretations of the effects of rainfall variability. We begin with the simple scenario of a basin receiving spatially uniform rainfall of varying intensities and durations and subsequently investigate the role of storm advection velocity, storm variability characterized by variance, spatial correlation and intermittency. Finally, we use a realistic space–time rainfall field obtained from a popular rainfall model that combines the aforementioned features. For each of these scenarios, we employ a recent formulation of flow velocity for a network of channels, assume idealized conditions of runoff generation and flow dynamics and calculate peak flow scaling exponents, which are then compared to the scaling exponent of the width function maxima. Our results show that the peak flow scaling exponent is always larger than the width function scaling exponent. The simulation scenarios are used to identify the smaller scale basins, whose response is dominated by the rainfall variability and the larger scale basins, which are driven by rainfall volume, river network aggregation and flow dynamics. The rainfall variability has a greater impact on peak flows at smaller scales. The effect of rainfall variability is reduced for larger scale basins as the river network aggregates and smoothes out the storm variability. The results obtained from simple scenarios are used to make rigorous interpretations of the peak flow scaling structure that is obtained from rainfall generated with the space–time rainfall model and realistic rainfall fields derived from NEXRAD radar data.