According to Froude number from 1.7 to 2.5 a series of rollers develop on surface of jump, but at downstream side surface is smooth. The energy loss is low and a uniform velocity is maintained. The jump under se conditions is called a weak jump.

In non-gravity type weir thickness of floor is relatively kept less, and uplift pressure is largely resisted by bending action of reinforced concrete floor.

This weir is similar to spillway section of a dam. The body of this weir is kept as a low dam. A cistern is provided at downstream side for energy dissipation of falling waters from upstream to downstream side.

The diversion head work is generally divided into eight component parts, namely weir, divide wall, fish ladder, pocket or approach ladder, scouring sluices, silt prevention devices, canal head regulator, and river training works.

Generally length of hydraulic jump is calculated in a region where re is a heavy turbulence and it is found to be five times height of jump.

Modern concrete weirs with sloping downstream glacis are generally provided with low crest counter-balanced gates. This is now exclusively used on permeable foundations. Masonry weirs are suitable for hard clay and gravel foundations. Rock-fill weir is suitable for fine sandy foundations.

In certain cases when jump is high, n difference in a jump is large and it occurs suddenly or abruptly.

For value of Froude number from 4.5 to 9, when performance of jump is best, when jump is well balanced and energy dissipation is from 45 to 70%, n jump is called a steady jump.

In Gravity weir, weight of weir balances uplift pressure caused by seepage water. In non-gravity weirs, weight of concrete slab and divide piers toger keep structure safe against uplift.

Before start of monsoons fish migrate to upstream in search of warm water. So, refore some provision is made to make some space available for m to travel. And this achieved by construction of fish ladder as y provide room for movement and also slows down flow for easy traveling of fish.