Search results for "Return"
showing 10 items of 354 documents
Design storm prediction and hydrologic modeling using a Web-GIS approach on a Free software platform
2005
Abstract The aim of this work has been to implement a set of procedures useful to automatise the evaluation, the design storm prediction and the flood discharge associated with a selected risk level. For this purpose a Geographic Information System has been implemented using Grass 5.0. One of the main topics of such a system is a georeferenced database of the highest intensity rainfalls and their assigned duration recorded in Sicily. This database contains the main characteristics for more than 250 raingauges, as well as the values of intense rainfall events recorded by these raingauges. These data are managed through the combined use of the PostgreSQL and GRASS-GIS 5.0 databases. Some of t…
Using plot soil loss distribution for soil conservation design
2011
Abstract Soil conservation design is generally based on the estimation of average annual soil loss but it should be developed taking into account storms of a given return period. However, use of frequency analysis in soil erosion studies is relatively limited. In this paper, an investigation on statistical distribution of soil loss measurements was firstly carried out using a relatively high number of simultaneously operating plots of different lengths, λ (11, 22, 33 and 44 m) at the experimental station of Sparacia (southern Italy). Using a simple normalization technique, the analysis showed that the probability distribution of the normalized soil loss is independent of both the scale leng…
Soil and water losses from new citrus orchards growing on sloped soils in the western Mediterranean basin
2009
Ten representative research sites were selected in eastern Spain to assess soil erosion rates and processes in new citrus orchards on sloping soils. The experimental plots were located at representatives sites on limestone, in areas with 498 to 715 mm year−1 mean annual rainfall, north-facing slopes, herbicide treated, and new (less than 3 years old) plantations. Ten rainfall simulation experiments (1 h at 55 mm h−1 on 0·25 m2 plots) were carried out at each of the 10 selected study sites to determine the interill soil erosion and runoff rates. The 100 rainfall simulation tests (10 × 10 m) showed that ponding and runoff occurred in all the plots, and quickly: 121 and 195 s, respectively, fo…
Multivariate Statistical Analysis for Water Demand Modeling
2014
The actual level of water demand is the driving force behind the hydraulic dynamics in water distribution systems. Consequently, it is crucial to estimate it as accurately as possible in order to result in reliable simulation models. In this paper, a copula-based multivariate analysis has been proposed and used for demand prediction for given return period. The analysis is applied to water consumption data collected in the water distribution network of Palermo (Italy). The approach showed to produce consisted demand patterns and to be a powerful tool to be coupled with water distribution network models for design or analysis problems. (C) 2014 Published by Elsevier Ltd.
Investigating the changes in extreme rainfall series recorded in an urbanised area
2002
The aim of this study is to investigate and quantify changes in the rainfall regime of the metropolitan area of Palermo characterised by increasingly strong urbanisation. The rainfall data, considered in this study, were collected on a yearly basis from eight rain gauges within and outside the metropolitan area of Palermo, Sicily, Italy. A preliminary analysis made on the annual total rainfall depths showed a global reduction of total annual rainfall, with two different trends: more regular for the series observed in the rain gauges within the urbanised area and more variable for the series observed in the rain gauges outside the area. A further analysis has been performed using the series …
Estimating soil loss of given return period by USLE-M-type models
2020
Many field investigations have clearly shown that rare and severe events control total soil erosion occurring over a long time period with up to 92% of total soil erosion over a 7‐year period resulting from just three daily events. Therefore, soil conservation strategies should be developed taking into account large events rather than long‐term average erosion. From an engineering point of view, establishing the soil loss of a given return period is needed. This can be obtained by the frequency analysis of soil loss measurements or by suitable soil erosion models. The USLE‐M modified and USLE‐M based are two empirical Universal Soil Loss Equation‐Modified (USLE‐M) type models which were dev…
Contributions to the study of returns to education : the Tunisian case
2016
In Tunisia, enrollment rates in tertiary education had soared up over the past two decades. A significant increase of student annual flows imposed the implementation of reforms that led to an increase in the number of higher education institutions and universities. One of the challenges in Tunisia and many African countries is to improve the efficiency of education systems to promote employability and graduates employment. This thesis discuss the question of the efficiency of education from an economic approach based on returns to education in the labor market. The first chapter analyses private returns to education particularly higher education in African countries. Our findings highlight …
Investing in a PhD : Human capital or cultural capital ?
2005
The first part is mainly devoted to the study of the theoretical positions of Gary Becker and Pierre Bourdieu, the main theme being the vision of education as a capital. The notions of human capital (Becker) and cultural capital (Bourdieu) are presented, compared and criticised, each one being replaced in its theoretical context. The second part is devoted to empirical analyses concerning the PhD. We first try to assess the monetary return on a PhD. Then we look for the reasons why people pursue study at doctoral level, knowing that the monetary return can not by himself explain this decision. The PhD appears mainly as a way to work in higher education and public research. More than human c…
The Returns to Education in Rwanda
2005
05077; International audience; Based on data from the 1999–2001 Household Living Conditions Survey conducted by the Ministry of Finance and Economic Planning, we estimate wage equations for employees in Rwanda, treating the choice of employment sector as an endogenous process and making separate estimates for workers in the modern and traditional sectors of the economy. The results show that returns to education increase with the level of education, contrary to the pattern typically reported in the literature and that the returns to higher education is particularly high in Rwanda. A noteworthy feature in the results is that the returns to education are quite different across sectors of empl…
Active macro-zones algorithm via multidomain SBEM for strain-hardening elastoplastic analysis
2010
In this paper a strategy to perform strain-hardening elastoplastic analysis by using the Symmetric Boundary Element Method (SBEM) for multi-domain type problems is shown. The procedure has been developed inside Karnak.sGbem code by introducing an additional module.