headwaters

Preposition: of

• river: The headwaters of the main river are a network of clay streams fed by chalk springs.
• stream: It also covers the headwaters of several other streams.
• tributary: The area of work is the headwaters of the second most important tributary of the Nile from Ethiopia.

Converse of object

• examine: He was also to examine the headwaters of Tullock's creek as he passed it and send me word of what he found there.
• form: The drift geology map also highlights spreads of alluvial deposits associated with the floodplains of the rivers that form the headwaters of the Lagan.
• reach: In 1540 Orellana and some 50 Spanish soldiers crossed the Andes and reached the headwaters of the Amazon River.

Adjective modifier

• upper: In so doing, China hoped to save remnants of forest cover on the upper headwaters.