निम्नलिखित में से कौन सा घटक नहर अपवर्तन शीर्ष-कार्य (canal diversion head-work) प्रणाली का हिस्सा नहीं है?

To reclaim salt-affected land, the accumulated salts must be leached out from the root zone by supplying:

In a canal outlet, which type of module maintains a constant discharge irrespective of fluctuations in water levels in both the distributing channel and the field channel?