Introduction
Follow the Water (FtW) tool was developed to improve the understanding of water flows in irrigation systems by visualising flows and quantifying the reuse of water in a simple and understandable manner. The tool is primarily to build technical capacities and develop initial design of irrigation systems or their modernization.
Incorporating water reuse in agricultural water management strategies and processes starts with the distinction between consumed and non-consumed flows. This conceptual framework dictates that water diverted to irrigation schemes can be divided into the following components:
- The Consumed Fraction, comprising:
- Beneficial Consumption (for the purpose intended or another beneficial use);
- Non-Beneficial Consumption (such as by weeds, evaporation from wetted surfaces, or capillary rise during a fallow period);
- The Return Flow Fraction, comprising:
- Recoverable flows (water flowing to drains and back into the river system for possible diversion downstream, and percolation to freshwater aquifers);
- Non-Recoverable flows (percolation to saline aquifers, outflow to drains that have no downstream diversions or direct outflow to the ocean).
Concept
The Follow The Water (FtW) tools help to understand water flows in irrigation systems. The basic concept of the tool is that an irrigation system has four main components:
- A main canal
- Secondary canals
- Drains
- Irrigation Blocks (10 to 10,000 ha)
The FtW tool comprises of virtual tracers, which is an innovative approach to follow water from the source to the point of use, virtually. It also takes into account the return flows from the fields that are available for reuse for downstream users within an irrigation system. By allowing users to visualise differences in water fractions as per the irrigation type (e.g. border, sprinkler, furrow, and drip), the tool offers insights on the efficiency of different irrigation techniques in terms of return flows and outflows from the system.
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Capacity Building on Water Accounting Under the Water Scarcity Program for Asia-Pacific
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Follow the Water: Reuse of Water in Irrigated Systems
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