Debris and Hyper-concentrated Flows : Overview and Perspective

Debris and hyper-concentrated flows are among the most destructive of all water \u2013 related disasters. They mainly affect mountain areas in a wide range of morpho-climatic environments and in recent years have attracted more and more attention from the scientific and professional communities and concern from public awareness, due to the increasing frequency with which they occur and the death toll they claim. In this context, achieving a system of debris and hyper-concentrated flow constitutive equations is a task which has been given particular attention by scientists during the second half of the last Century. In relation to these issues, the paper reviews the most updated and effective procedures , nowadays available, suitable to predict the triggering and mobilising processes of these phenomena and proposes a new set of mathematical models able to assess the depth of the wave and the velocities of the liquid and solid phases of both non-stratified (mature) and stratified (immature) flows following flash-floods and dam-break events , in one and two dimensional schemes. Different experimental cases of dam-break situations in a square section channel were considered for the purpose of comparing results. These tools will allow, on one hand, to better focus what to observe in the field and, on the other hand, improve both mitigation measures and hazard mapping procedures

Thermal fluid dynamics of water droplet in sprinkler irrigation : Phenomenological analysis and modelling

A thorough understandingof the factors affecting spray flow and evaporation losses in sprinkler irrigation is important for developing appropriate water conservation strategies. To properly tackle this problem ,relevant theoretical and experimental studies have been carried out during the second half of the last century. Notwithstanding all these efforts, the phenomenon of aerial evaporation of droplets exiting from a nozzle has not been fully understood yet and something new has to be added to the description of the process to reach a better assessment of the events. To this end, a mathematical model for irrigation sprinkler droplet ballistics , based on a simplified dynamic approach to the phenomenon ,has been presented. The model proves to fully match the kinematic results obtained by more complicated procedures. Moreover,fiel trials showed the model to reliably estimate spray evaporation losses caused by environmental conditions. Further analytical and experimental activities are needed to gain a better understanding of water flow and waste in sprinkler irrigation practice

Conjunctive use of surface and groundwater

The world's fresh water resources are unequally distributed both in time and in space.Until recently water resources management focused on reallocating water to when and where it was required,a sully-side of fragmented approach. Nowadays there are signs that water resource availability is dwindling -due to both population growth and increased per capita water use- and eco-systems are being damaged. To face this challenge a new holistic approach is needed. This approach includes the integrated or conjunctive use of surface and groundwater resources and takes account of social ,economic and environmental factors. Moreover ,it recognizes the importance of water quality issues. In this context ,the paper examines the main aspects and problems concerned with the planning,design ,construction and management of conjunctive use of surface and subsurface water resources,along with its environmental impacts and constraints to sustainable development.The importance and role of research thrust,technology transfer,institutional strengthening ,effective partnerships between governments and stakeholders ,and sound financial frameworks are also examined. Finally ,the challenges anf benchmarks for future actions that the scientific community and planners have to face and deal with ,are briefly outlined

analysis of an in flight water droplet literature based considerations and novel perspectives

The characterization of water jets and of each single droplet composing them is complicate and challenging because of the many non-linarites affecting both the system properties and the process itself. This is why literature generally offers empirical or semi-empirical modelling attempts, too tight to the specific case study conditions, albeit recent systematizations have been provided [1-3]. Thus it is currently arising as a main scientific issue the following question: which is the best way to represent and describe the dynamics of water droplets travelling in air? In addition to a complementary question, are there new possibilities to explore the problem looking at it from another point of view

Flood-risk assessment and hazard mitigation mesures : case studies and lessons learnt in Italy

The effect of climate change and the growing world population are together increaing both the chance of flooding and the consequences. In Italy , in the wake of the floods that plagued the northen part of the country in the fifties and sixties ,a process was set in motion aimed at developing a new integrated approach to water management, at the catchment level,suitable for coping with water related disasters.In this context,three case-studies of flood risk management and hazard assessment are described

Analysis of an in-flight water droplet: literature-based considerations and novel perspectives

e characterization of water jets and of each single droplet composing them is complicate and challenging because of the many non-linarites a#ecting both the system properties and the process itself. is is why literature generally o#ers empirical or semi-empirical modelling attempts, too tight to the speci$c case study conditions, albeit recent systematizations have been provided [1-3]. us it is currently arising as a main scienti$c issue the following question: which is the best way to represent and describe the dynamics of water droplets travelling in air? In addition to a complementary question, are there new possibilities to explore the problem looking at it from another point of view