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Scour around a bridge pier is one of the major possible causes of the hydraulic failures of a bridge. A typical sediment-water-structure interaction at the upstream junction of the bridge pier initiates a vortex system, the primary vortex of which is responsible for local scour around the pier. The growth of the primary vortex can be arrested by retaining it on a rigid surface as on a collar plate. A number of experiments covering various sizes of collar plates were carried out in an effort to minimize scour around a bridge pier. A collar plate of size three times the diameter of the circular pier, 0 or larger when placed at the average bed level assures I 00% scour reduction while a collar plate of size 20 placed 0.10 below the bed does not allow scour depth to go beyond it. Anticipating degradation of general bed level, a group of multiple collar plates of smaller size were employed at the laboratory scale to reduce the scour considerably. A group ofthree collar plates of size 1.50 having an inter-plate spacing C, of0/6 with the middle plate placed at the average bed level reduces scour by 83% in comparison to the scour depth of an unprotected pier. The composite device, apart from being axis symmetric, is highly suited to degrading river beds.

Sub-surface water contamination has become a topic of main concern due to anthropogenic activities. MSTs were performed to appraise the seasonal and spatial variations in quality of sub-surface water and to trace the sources in NE Haryana. WQI was computed to analyse the quality of overall groundwater for domestic purposes during pre- and post-monsoon periods. The post-monsoon season water samples were found to be good for human consumption compared to pre-monsoon season. HCA, DA and PCA were performed to the quality of sub-surface water data computed on 14 elements from 30 locations geographically well-distributed across the area. Thirty sampling sites were classified into 02 clusters using HCA, group two having higher contamination than group one. The most significant elements accounting for spatial and seasonal variations in quality of sub-surface water of the study region was obtained by using DA. For the combined dataset of the pre-monsoon and post-monsoon seasons of 2017 the temporal and spatial DA identified pH, Na, Cl, TDS, Mg and F as the six most significant element, which distinguishes between water pre-eminence in the two seasons and accounts for 88.34% spatial and 100% seasonal assignation of cases. PCA was used to the data observed from the 02 groups, which obtained four varimax-factors in each group, accounting 77.54 and 84.77% of the total variance, respectively. Varimax factors evolved from PCA represented that quality of sub-surface water variation is possibly attributed by multiple geogenic, anthropogenic factors, ion exchange processes and rock-water interactions in groundwater.

Excessive scouring of sediment around bridge piers plays a major role causing failure of waterway structures. To prevent scouring around bridge piers, it is necessary to determine the maximum scour depth. In the past, researchers have conducted extensive laboratory work around flow structures with the help of scaled models. But most of the work has been carried out around an isolated pier and the work around a group of piers is relatively much lesser. To fill up the gaps in information, an experimental study was conducted in a recirculating water flume 15 m long, 0.4 m wide and 0.6 m high containing uniform sediment of mean size, d 50 = 0.30 mm. Experiments on cylindrical pier models of size 42 mm were run at a velocity equal to 0.89 times the critical velocity, u c. Three different arrangements i.e. Tandem, Side by Side and Staggered have been used to analyze the effect of spacing and orientation on scour. From the initial observations it was concluded that, in the case of Tandem arrangement when the spacing between the piers was 16 times the diameter of the pier and more, both the piers showed independent behavior. But if the spacing between the bridge piers is 0D, then both the piers behave like a single pier and the scour depth was found to be 41% greater than that of a single pier. However, when the clear spacing was greater than 1.5 times for side by side and 2.5 times for staggered arrangement, the piers behaved independently.