Transforming Vulnerability Indexing for Saltwater Intrusion into Risk Indexing through a Fuzzy Catastrophe Scheme

Mapping vulnerability to Saltwater Intrusion (SWI) in coastal aquifers is studied in this paper using the GALDIT framework but with a novelty of transforming the concept of vulnerability indexing to risk indexing. GALDIT is the acronym of 6 data layers, which are put consensually together to invoke a sense of vulnerability to the intrusion of saltwater against aquifers with freshwater. It is a scoring system of prescribed rates to account for local variations; and prescribed weights to account for relative importance of each data layer but these suffer from subjectivity. Another novelty of the paper is to use fuzzy logic to learn rate values and catastrophe theory to learn weight values and these together are implemented as a scheme and hence Fuzzy-Catastrophe Scheme (FCS). The GALDIT data layers are divided into two groups of Passive Vulnerability Indices (PVI) and Active Vulnerability Indices (AVI), where their sum is Total Vulnerability Index (TVI) and equivalent to GALDIT. Two additional data layers (Pumping and Water table decline) are also introduced to serve as Risk Actuation Index (RAI). The product of TVI and RAI yields Risk Indices. The paper applies these new concepts to a study area, subject to groundwater decline and a possible saltwater intrusion problem. The results provide a proof-of-concept for PVI, AVI, RAI and RI by studying their correlation with groundwater quality samples using the fraction of saltwater (f_sea), Groundwater Quality Indices (GQI) and Piper diagram. Significant correlations between the appropriate values are found and these provide a new insight for the study area.

     

In-bend pressure drop and post-bend heat transfer for a bend with a partial blockage at its inlet

This paper describes a three-part numerical investigation of fluid flow and heat transfer in a never-previously-studied pipe bend situation. The investigation deals with downstream fluid-flow and heat transfer processes which are affected by upstream flow disturbances. The studied physical situation is a 90° pipe bend fitted with a wall-adjacent obstruction that partially blocks the inlet cross section. The first phase of the work consisted of validating numerical simulation results with experimental data. In the second phase, the impact of the inlet flow distribution on the pressure drop is determined. Heat transfer downstream of the bend exit comprises the third section of the paper. The heat transfer results are reported in terms of the circumferentially averaged Nusselt numbers which are displayed as a function of axial position for Reynolds numbers between 100 and 10,000. It was found that the disturbances caused by the blockage significantly enhance the Nusselt number values.