Basin Irrigation & Flood It Evenly
Sizes basins
Enter the available stream flow, the set time and the target depth to get the largest basin area your stream can flood uniformly — in square metres and hectares.
Size a level basin
Next: border off basins of about 1,440 m² so each fills to 75 mm within the set time; on coarse soils use smaller basins so water spreads before it soaks past the root zone.
Assumes water ponds and infiltrates uniformly; very sandy soils or long advance times need smaller basins or a larger stream.
Basin irrigation — key facts
- Method
- Flood a level, bunded plot
- Basin area
- Flow × set time ÷ target depth
- Best for
- Flat land, rice, orchards
- Why size it
- Too big = uneven flooding
- Bigger stream
- Floods a bigger basin in the set time
- 1 ha
- = 10,000 m²
- Pair with
- Furrow & infiltration tools
- Privacy
- Runs in your browser; nothing uploaded
Match the basin to the stream you have
Check-flooding is the oldest surface irrigation method: bund a level plot, let water in until it stands at the right depth, then move on. The trick is sizing each basin to the stream you can deliver. Too large, and the water reaches the target depth at the inlet while the far corner is still dry — uneven, wasteful watering. Sized so the stream fills it to the target depth in the set time, the whole basin floods evenly. The rule is simple: basin area equals stream flow times set time, divided by target depth.
This tool computes the largest basin area your stream can flood, in both square metres and hectares, and carries through the stream flow and target depth so you can adjust quickly. Use it to lay out check basins that water uniformly. Pair it with the Furrow Stream Size, Soil Infiltration Rate and Paddy Bund tools to design the whole surface system.
Flood it evenly
Size to the stream so the whole plot fills.
Stop the waste
No over-watering the inlet, no dry corners.
Plan the layout
Basin area in m² and ha to match your map.
Work any stream
See the biggest basin your flow can handle.
Frequently Asked Questions
What is basin (check) irrigation?+
Basin irrigation, also called check flooding, divides a field into level, bunded plots — basins — that are flooded one at a time to a target depth. It suits flat land and crops like rice, orchards and close-growing field crops, and is the simplest surface method because the water just sits and soaks in rather than running along furrows.
How is the basin area calculated?+
Basin area = stream flow × set time ÷ target depth. The stream flow is the rate water arrives at the basin, the set time is how long you let it run, and the target depth is the layer of water you want to apply. Multiply flow by time to get the volume delivered, then divide by the depth to get the area that volume can cover.
Why must the basin be small enough?+
A basin must fill to its target depth quickly and evenly. If the basin is too big for the stream, the far end is still dry while the inlet end is already over-watered, giving uneven application and wasted water. Sizing the basin to what the stream can flood in the set time keeps the whole plot watered uniformly.
What is the set time?+
The set time is how long water runs into one basin before you move it to the next. It is chosen so the soil takes in the planned depth without over-soaking the inlet area. Together with the stream flow it fixes the volume delivered, and therefore the area that can be flooded to the target depth — which is what this tool returns.
What target depth should I use?+
The target depth is the net water you want to add to refill the root zone, typically the soil’s readily available water at the chosen irrigation interval — often in the range of 50–100 mm for field crops, more for ponded rice. Pick the depth your crop and soil need; the basin area scales inversely with it for a given stream and time.
How does stream flow affect basin size?+
The bigger the stream, the larger the basin it can flood in the same set time, because more volume arrives per minute. A small stream forces small basins flooded in sequence; a large stream lets you flood big basins quickly, which improves uniformity. The calculator shows the maximum area your particular stream can handle.
What units does the tool give?+
It reports the basin area in both square metres and hectares so you can match it to a field map, and it carries through the stream flow and target depth you entered. One hectare is 10,000 m², so the hectare figure is simply the square-metre area divided by ten thousand for quick comparison with your plot sizes.
How is basin irrigation different from furrow?+
In basin irrigation the whole plot is flooded and the water soaks straight down, so it suits flat land and ponded or close-spaced crops. In furrow irrigation water runs along channels between ridges and soaks in sideways, suiting row crops and gentle slopes. See the Furrow tools for sizing the stream and run length in that method.
Are the results exact?+
They are sound planning estimates from your stream flow, set time and target depth, assuming the water spreads evenly. Real basins lose some water to the advance front, evaporation and uneven leveling, so leave a margin, level the basin well, and confirm with a field trial before laying out a whole system.