Hydraulic and Hydrology

Experimental investigation has been performed to understand the hydraulic behaviour of non-rectangular piano key weir where either the side wall angle or the side wall inclination angle is greater than zero. Five physical models were prepared: one standard type-A rectangular model, and four non-rectangular models designed in similar dimensions to the rectangular one. Tests were conducted in a 15m long, 0.3m wide and 0.45 m deep rectangular glass-walled experimental flume. Effects of side wall angle and side wall inclination angle on discharge coefficient were investigated, so that the head-discharge relationship for each model is achieved. It was concluded that changing those angle to about 10° has negative effect on discharge capacity, while changing them around 5° can increase the capacity when appropriate change in the inlet and outlet keys widths ratio.

Hydraulic jump type energy dissipaters are widely accepted methods of energy dissipation
while designing the hydraulic structures like dams, weirs and barrages. They are popular for
their simplicity and efficiency, but have certain limitations when there is variation in
discharge conditions. The energy dissipaters satisfactorily function at design discharge
condition. But in case of varying discharge conditions they are not efficient as the location
of hydraulic jump tends to shift on apron. This would result in percentage reduction in
energy dissipation and in turn damage hydraulic structures and adversely affect tail channel
conditions. Therefore it is necessary to address the issue of controlling the location of
hydraulic jump and evolve a new technique for the same. This paper discusses the design of
hydraulic jump type stilling basin for the overflow weir of canal escape at Warana dam
(India). It also throws light on the aspect of jump location and percentage energy dissipation.
A physical model study is carried out by applying Froude’s model law.

The allocation of groundwater resources has been a challenge for many years due to its unforeseen side effect and lag time issues, which are often overlooked. The full impact of groundwater utilization/abstraction takes time to realize its effect at its full. In this paper, long‐term effects and groundwater dynamics were assessed using a water balance model and a time series analysis, respectively. Undeveloped groundwater systems are commonly found in a state of equilibrium, where, on average, equal amounts of water are recharged and discharged. A water budget is a static accounting of the state of the system at a given time, often before the system is developed. Water balance analysis was carried out together with the groundwater through flow, hydrograph, and surface‐groundwater interaction analysis (base flow index) to develop a conceptual water balance model, which is a very basic representation of a complex natural aquifer system and is instrumental to constrain and build a robust numerical model that can be readily justified and updated. A noble approach was employed to assess and constrain the discharge coming out of the model area to sustain the lake level, located to the north of the study area, using the whole lake catchment and lake water balance analysis. Based on the lake water balance, there is a deficit between input and output computation, and hence there should be a groundwater input to sustain the historical lake area. The analysis showed that the model area contributes 40% of the lake catchment, and hence the portion of the groundwater inflow feeding the lake was computed. This is one of the means to constrain the discharge, which adds more confidence to the recharge estimation. This is very important because the size of a sustainable groundwater development usually depends on how much of the discharge from the system can be captured by the development. Capture is independent of the recharge. Instead, it depends on the dynamic response of the aquifer system to the development. The idea that knowing the recharge is important in determining the size of a sustainable groundwater development is a myth and has no basis. The important entity in determining how a groundwater system reaches a new equilibrium is capture. How capture occurs in an aquifer system is a dynamic process. Following this study, lake water balance assessment was indirectly considered as prior information for the numerical model calibration of the discharge from the model area using a conductance parameter. Conductance is a key parameter to estimate the discharge volume together with the change in the simulated hydraulic head between time steps. The water balance error highlights which one is more sensitive, and this could help to assist in planning for future data collection/field work and where to invest the money. The water balance computation helps to figure out the degree of surface‐groundwater interaction, uncertainty, sensitive parameter, helps in the decision to invest time and money, and operates as a cross check with other analytical or numerical modelling.

A method is presented to analyze the interaction between groundwater and Lake Linlithgow (Australia) as a case study. A simplistic approach based on a " node " representing the groundwater component is employed in a spreadsheet of water balance modeling to analyze and highlight the effect of groundwater on the lake level over time. A comparison is made between the simulated and observed lake levels over a period of time by switching the groundwater " node " on and off. A bucket model is assumed to represent the lake behavior. Although this study demonstrates the understanding of Lake Linlithgow's groundwater system, the current model reflects the contemporary understanding of the local groundwater system, illustrates how to go about modeling in data‐scarce environments, and provides a means to assess focal areas for future data collection and model improvements. Results show that this approach is convenient for getting first‐hand information on the effect of groundwater on wetland or lake levels through lake water budget computation via a node representing the groundwater component. The method can be used anywhere and the applicability of such a method is useful to put in place relevant adaptation mechanisms for future water resources management, reducing vulnerability and enhancing resilience to climate change within the lake basin.