Effect of Top Slope on Submergency Ratios for Standing Wave Weirs.

Document Type : Research Studies

Authors

1 Professor of Irrigation and the Vice Rector of Assiut University, Assiut, Egypt.

2 Associate Professor, Civil Engineering Department, Faculty of Engineering, Mansoura University, Mansoura, Egypt.

3 Assistant Professor, Civil Engineering Department, Faculty of Engineering, Assiut University, Assiut, Egypt.

Abstract

It has been always the main objective of many of the Egyptian investigators to find the best ways to restore enough irrigation water to be well regulated and distributed with the right amount and the best HOW and WHEN to be applied all over the agricultural lands. Standing wave we are became, since long time ago, one of the very widely traditional irrigation work used to regulate, control and measure flow rates through irrigation distribution system. 
The main objective of this research study was to find out the effect of changing the top slope of the standing wave weirs on the ratio of submersion for the sake of practicing higher flow rates Influenced by higher values of submergencratios, experiencing minimum heading up, resulting the least head lose through the system. 
A well proportional scaled dynamically similar standing wave weir model was constructed across an artificially made controllable trapezoidal canal. Under different flow condition and with the variation of seven top slopes, (3: 1, : 1, 5:1, 10 : 1, 15 : 1, 20 : 1 and Zero : 1), relationship
between upstream and down-stream water heads were drawn to reach the modular ranges applying different flow rates. Also, distinct Correlations between submergency ratio and the upstream water heads versus the seven top slopes individually, 88 a third variable, were achieved where an inverse relationship was found 
Moreover, illustrations regarding the effect of the top slope on both the stabil1ty of flow over the weir and on the submergency ratios and thus on the weir flow rates were demonstrated. Definite conclusions were drawn, anong them the suitability of the top slope 5:for relatively smaller discharges while the top slope 20.1 were found to be sutiable 
for the higher ones. Also, several recommendations were emphasised concerning the limitations for using some of these top slopes for practical purposes. That in addition to other recommendations for future studies relevant to the same course of study. 

Main Subjects