Journal of Irrigation and Drainage Engineering

The studies on labyrinth side weirs have received considerable attention in existing literature. A mobile bed, which causes significant morphological bed changes, can be induced by the side overflow weir. In this study, the local scour depths that occur near a triangular labyrinth side weir at a 90° angle in a straight channel with an alluvial bed were experimentally examined under steady flow conditions with free overflow of the weir. Based on a dimensional analysis applied according to the parameters of the study, it was determined that dimensionless equilibrium scour depth is dependent on the approach flow intensity, dimensionless side weir crest height, dimensionless median grain size, dimensionless side weir opening, and dimensionless volumetric amount of upstream sediment feed under live-bed scour conditions. For different combinations of weir opening length and weir height, data for a set of 81 runs were obtained. The results show that an increase in weir crest height results in a decrease in dimensionless maximum scour depth. In the clear-water scour experiments, sediment deposits were observed downstream of the weir. In the live-bed scour experiments, the dimensions of the scours and sediment deposits that occurred upstream and downstream of the weir exhibited periodic changes. Good consistency was attained in the developed empirical equations between the calculated and measured values of the equilibrium scour depth.

In India in recent decades, groundwater has emerged as a principal source for meeting drinking and irrigation needs. As a result, groundwater depletion and overextraction are acknowledged as a major concern. Different policy interventions are being explored to augment the management of aquifers. Aquifer storage and recovery (ASR) is one such intervention that is becoming popular among government agencies, developmental actors, and even farmers for recharging and recovering water from aquifers. However, the selection of a suitable location and appropriate aquifer for recharge is challenging. The main objective of this study was to classify site selection criteria for ASR installations in different types of aquifers in North India. In this study, both scientific indicators (i.e., rainfall, elevation, soil and aquifer characteristics, surface and groundwater quality) and social characteristics (tacit knowledge, land ownership, willingness to participate) were evaluated to create an integrated ASR site selection criterion. The results indicated that ASR sites could not be appropriately identified solely based on available metrological, geospatial, and geohydrological data. Socioeconomic parameters should be an integral part of the decision-making process for the site selection for ASR. Based on these scientific indicators and social characteristics, a total of seven potential ASR sites (three in the village of Nekpur and four in the village of Meyar) were selected at Rajgir, Nalanda, Bihar, India. Although this integrated site-assessment framework was designed based on 12 indicators in the context of the marginal alluvial plains for the mid-Ganga regions in this study, the general principles adopted in this study can be applicable to other regions.

A laboratory experiment was conducted to study the effects of the emitter discharge rate (EDR) on the distribution of water and salt in a manipulated soil texture of a coarse soil surrounded by takyric solonetz. The objective was to develop a simple method to rapidly determine a suitable EDR for the reclamation of takyric solonetz using drip irrigation. Major influences on soil structure were observed at EDRs $\le 0.5\mathrm{L}/\mathrm{h}$, and slight influences were observed at EDRs $>0.5\mathrm{L}/\mathrm{h}$. This was consistent with the changing trend of irrigation amount as the EDR increased from 0.1 to $2\mathrm{L}/\mathrm{h}$, with the irrigation amount decreasing rapidly at first and then remaining constant during a one-time irrigation. A method is proposed to determine the EDR based on the changing trend. The method considers the EDR at the inflection point—i.e., the point at which the irrigation rate declines from quick to slow—to be the ceiling value, where a lower value is considered better. A suitable EDR below the ceiling value is then selected that satisfies the peak period of crop water consumption.