Water Use Efficiency (WUE) is defined as the yield or marketable crop production obtained per unit of water applied (or evapotranspired):

Where $Y$ is crop yield/production (kg/ha) and $W$ is water applied or consumed (ha-mm or $\text{m}^3$). It is generally expressed in kg/ha-mm or kg/$\text{m}^3$.

During border strip surface irrigation, water flows as a thin sheet over the soil surface. Because water infiltrates into the soil continuously along the path of advance, the discharge rate decreases along the flow length ($dQ/dx \lt 0$, spatially varied flow). Furthermore, at any given cross section, the depth and flow velocity vary over time ($dQ/dt \ne 0$). Therefore, overland flow in a border strip is an example of spatially varied unsteady flow with decreasing discharge.

In sprinkler irrigation design, Christiansen's Uniformity Coefficient ($C_u$) indicates the spatial uniformity of water depth collected in catch cans across the irrigated area:

For acceptable irrigation performance under normal wind velocity (less than 8 km/h) and rated nozzle operating pressure, an 80% to 85% uniformity coefficient is considered the minimum acceptable standard.

Drainage coefficient ($D_c$) is the depth of water (in cm or inches) removed from the drainage area in 24 hours (1 day).
Discharge $Q = 0.2\text{ m}^3/\text{s}$
Volume of water drained in 24 hours:

Drainage Area $A = 250\text{ ha} = 250 \times 10,000 = 2,500,000\text{ m}^2$
Depth of water removed ($D_c$):