Hydrology: Current Research

During last 20 years, Sicily has been affected by an increasing sequence of extreme weather events that have produced, besides huge damages to both environment and territory, the death of hundreds of people together with the evacuation of thousands of residents, which have permanently lost their houses. The aim of this paper is to describe the Weather Research and Forecasting Model (WRF) and to report findings obtained, through this model, in a relevant case study. On purpose a WRF Local Area Model (LAM) has been used to re-analyze the heavy rainfall occurred during the night of October 10th, 2015 in Sicily. The re-analysis of this case study, shows how a LAM, suitably configured for the complex orography of Sicily, is able to forecast this kind of extreme weather events. This study clearly shows how forecasts obtained using this kind of model can be very useful to reduce the hydrogeological impact of extreme events on the environment and on territory.

This study sought to investigate hydrological characteristics of lower Nzoia sub-basin in Kenya. Trend (long and medium) utilized graphical and statistical approach. Extreme value (EV) analysis based on frequency, annual maximum flows, exceedance probability, low flows and probable maximum precipitation was used. Quality control showed consistency in rainfall, temperature and discharge datasets. Maximum-minimum monthly and annual flows and rainfall showed maximum flows centered in March-to-May (peak) with increasing temperature. Trends, seasonality and cycles were identified and maximum values in rainfall and discharge closely followed the pattern for peak rainfall seasons. Based on the flow magnitudes and 100-year return period, the upstream station (1EE01) had lower values compared to downstream station (1EF01) for different assumed distributions and thus 1EF01 assumed to be more reliable. Exponential and Pareto distributions indicated a normal tail and thus appropriateness of EV1/Gumbel distribution in calibrating AM series. Best conventional calibration results based on assumed distributions using EV1/Gumbel superimposed with the extreme value distribution fitted along with the exponential/Pareto Q-Q plots for comparison. Estimated maximum withdrawal in monthly terms for 1EE01 and 1EF01 was 262.5 and 368.4 cumecs respectively. Analyses of low stream flow indicate probable availability of water in streams at different return periods.

Within the framework of the theory of plane steady filtration of an incompressible fluid according to Darcy’s law, two limiting schemes modeling the filtration flows under the Joukowski tongue through a soil massif spread over an impermeable foundation or strongly permeable confined water-bearing horizon are considered.

Causes and consequences of climate variability of which the fluctuation in rainfall amounts over time represent an important indicator is indeed an area that has continued to generate research attention. The aim of this paper is, therefore, to evaluate the concentration and variability of rainfall in time using Precipitation Concentration Index (PCI) based on monthly precipitation over 38 years period (1976–2013) and its implications for flooding and water supply in the town. Data for the study were collected from NIMET, Lagos. The PCI was calculated for annual, seasonal and decadal scales using annual, wet and dry season equations. Result shows that annual PCI value range from the lowest of 12 in 1976 to the highest of 20 in 1987. About 78% of the years were characterized by PCI values that fall within moderate range, an indication of moderate precipitation distribution within the 38-year period, while 24% of the years recorded annual value within the irregular range indicating an irregular rainfall distribution and concentration across the months. Again, the fact that many months have PCI values within ≥ 16.7 is a further manifestation that almost 90% of the rainfall occurred in 6 months. These results show that the area is having reasonable floods with consequent pollution of the surface water bodies as well as soil erosion as observed in the town. It is, therefore, recommended that the Awka Capital Territory Development Authority (ACTDA) should take cognizance of this result in the planning of the new layouts and redevelopment of the old areas of the town.

Two moderate earthquakes with magnitudes of 6.0 and 5.8 occurred in active tectonic crustal structures of the Po Plain in the area of Modena City in Northern Italy. These events generated temporary and/or permanent environmental changes with much damage, leading to 27 deaths. These quakes occurred on May 20, 2012, at 02:03 UTC, and on May 29, 2012, at 07:00 UTC, at depths of 5.5 and 10.1 km, respectively. In order to investigate for effects from the earthquakes on the fluorescence spectra and ion composition of groundwater within the affected area, available mineral water bottled prior to and post the two shocks were collected. Specifically, the regular production lines at the bottling plants of the brands Lieta, Ventasso, Cerelia and Monte Cimone situated in the nearest Appennine chain, contributed to this study. These bottled waters where analyzed for their fluorescence spectra using the synchronous scanning method. Variations of fluorescence intensity a month before the first earthquake of May 20, 2012, appeared to be significant only at Monte Cimone spring, where high density water samples were available. Likewise, variations in ion compositions evidenced peaks at a month before the first earthquake and a month after the second one. pH and conductivity levels of only some springs also shown significant variations at a month before the first earthquake. These findings suggest that a realization of continuous measurement networks in areas prone to incidences by strong earthquakes could be useful for investigating any possible influence of earthquakes on water geochemistry.