Search results for "DRAIN"
showing 10 items of 417 documents
Percutaneous Nephrostomy in Obstructive Uropathy
1983
Since the original description by Goodwin in 1955, percutaneous nephrostomy (PNS) has assumed an important role in the management of obstructive uropathy. It was initially devised as an alternative to operative nephrostomy, but has now completely replaced the latter, for the following good reasons: 1. It can be done under local anesthesia. 2. It provides effective urinary drainage. 3. It carries an acceptable risk, with low morbidity and practically no mortality.
Flow hydraulic characteristics determining the occurrence of either smooth or abrupt sewer pressurization
2014
Laboratory experiments showed that pipe pressurization consequent on a drastic reduction in the downstream discharge can occur either by a gradual rising of the free-surface (“smooth” pressurization) or by propagation of a front filling the whole cross-section (“abrupt” pressurization). This study examines the free-surface flow characteristics that determine smooth or abrupt pressurization pattern through a theoretical approach using dimensionless variables. A critical flow rate value, which separates the pressurization patterns, exists for any given pipe diameter. For flow rates higher than this specific value, only abrupt pressurization occurs. For lower flow rates, either smooth or abrup…
A BMA Analysis to Assess the Urbanization and Climate Change Impact on Urban Watershed Runoff
2016
Abstract A reliable planning of urban drainage systems aimed at the mitigation of flooding, should take into account the possible change over time of impervious cover in the urban watershed and of the climate features. The present study proposes a methodology to analyze the changing in runoff response for a urban watershed accounting several plausible future states of new urbanization and climate. To this aim, several models simulating the evolution scenario of impervious watershed area and of climate change were adopted. However, it is known that an evolution scenario represents only one of all possible occurrence and it is not necessary the true future state, therefore it is needed to fin…
δ pattern of dissolved inorganic carbon in a small granitic catchment: the Strengbach case study (Vosges mountains, France)
1999
Abstract The transfers and origins of dissolved inorganic carbon (DIC) were studied for a year in a soil–spring–stream system in the Strengbach catchment, Vosges mountains, France. This 80 ha experimental research basin is located on the eastern side of the mountains, at an altitude ranging from 883 to 1146 m.a.s.l. and is mainly covered by spruce (80%). Brown acid and podzolic soils developed on a granitic basement, and, as a result, the DIC originates solely from CO2 generated by oxidation of soil organic matter. The ( δ 13 C DIC ) in catchment waters is highly variable, from about −22‰ in the springs and piezometers to about −12‰ in the stream at the outlet of the catchment. In the sprin…
River Contracts for Innovation in Territorial Governance
2016
Emerged in France in 1980s as agreements oriented to the requalification of rivers and lakes, river contracts represent an important outcome of the decentralization process, developed in Europe in reply to the growing institutional fragmentation. In this scenario, rivers have become a dialectic arena in which the exploitation and management of water resources came to terms with environmental instances, and offered the breeding ground for concerted efforts between policy makers, stakeholders and communities. In this chapter, the analysis is focused on the river contract model and the related set of instruments capable of supporting concerted and participatory management processes both with r…
Spatial prediction of soil erosion susceptibility using a fuzzy analytical network process: Application of the fuzzy decision making trial and evalua…
2018
Soil erosion is a worldwide threat that results in soil degradation, agriculture abandonment, and crop yield reduction. There is a need to find methods to survey soil erosion rates in order to improve and develop sustainable land planning. The present study utilizes new approaches based on the fuzzy set both in designing the problem (through the fuzzy decision making trial and evaluation laboratory) and in prioritizing the effective factors to mitigate soil erosion (using a fuzzy analytical network process, FANP). This study is first to apply these methods to soil erosion. A set of geo‐environmental factors influencing soil erosion was characterized to evaluate the potential risk of soil er…
Hydrological and hydraulic behaviour of a surface flow constructed wetland treating agricultural drainage water in northern Italy.
2020
Abstract A surface flow constructed wetland (SFCW) treating agricultural drainage water was investigated with the aim to detect modifications in hydrological and hydraulic characteristics after more than a decade of operation. Ponded infiltration tests were conducted to estimate the saturated hydraulic conductivity, Ks, of the surface soil layer at the point scale. At the global scale, infiltration rate, i, was computed from the water balance to detect leakages from the pervious wetland surface. Tracer tests were conducted to analyse the existence of preferential flow inside the system and to estimate its hydraulic retention time (HRT). Clogging phenomena occurred given a mean Ks value of 3…
Assessment of the changes of COD and color in rivers of Latvia during the last twenty years
1998
Analysis of long-term records of the concentrations of water color and chemical oxygen demand for nine river sites in Latvia is reported. The period of observations lasted for the last 20 years. Characteristic features of data include non-normal distributions, serial correlation, seasonality and presence of mostly significant downward trends. In Latvia, the main water quality changes could be explained by the changes of anthropogenic impact and the type of catchment management over the last 20 years.
Response of macrophyte communities and status metrics to natural gradients and land use in boreal lakes
2012
Abstract We studied the relations of aquatic macrophyte communities, ecological quality metrics and water quality to lake characteristics and to land use defined at multiple spatial scales (three lake marginal zones (LMZs) of contrasting width and the whole topographic catchment) in 110 boreal lakes in Finland using ordination and generalised additive modelling. Variation in macrophyte community composition of our lakes was related to water quality, land use, latitude and lake morphology. Relationships of macrophyte status metrics – the proportion of type-specific species (TT50), Percent Model Affinity (PMA) and Trophic Index (TI) – to land use were scale dependent. The proportion of agricu…
Deducing a Drain Spacing Formula by Applying Dimensional Analysis and Self-Similarity Theory
2016
For designing a steady state drainage system a drain flow formula coupled with the Dupuit-Forcheimer form of the differential equation of groundwater flow is used. At first, in this paper the most applied drain flow formulas in steady-state conditions are reviewed and compared using as dependent variable the ratio between the maximum water table height and the distance between two lines of parallel drains. These equation are also tested using experimental field data measured in three plot drained by surface pipe drains having different value of drain spacing. Then, applying the dimensional analysis and the self-similarity theory, a new drain spacing formula is theoretically deduced and comp…