The geographical distribution of water supply and demand in the UK is highly unequal. The table below provides hydrological and demographic data for four regional Water Resource Zones (WRZs):
| Water Resource Zone | Average Annual Rainfall (mm\text{mm}mm) | Population Density (people/km2\text{people/km}^2people/km2) | Per Capita Consumption (L/day\text{L/day}L/day) |
|---|---|---|---|
| Zone Alpha | 1,4201,4201,420 | 55 | 135 |
| Zone Beta | 590 | 440 | 160 |
| Zone Gamma | 910 | 120 | 145 |
| Zone Delta | 1,1501,1501,150 | 85 | 140 |
Using the data, identify the correct assessment of the water security status of Zone Beta and its underlying cause.
Zone Beta is in a water surplus because the high per capita consumption (160 L/day160\text{ L/day}160 L/day) indicates that the regional supply is more than adequate to meet all domestic and industrial demands.
Zone Beta is in a water deficit because it has the lowest physical water supply (lowest rainfall) combined with the highest concentrated demand (highest population density and per capita consumption).
Zone Beta is in a state of economic water scarcity because, while rainfall is low, the main barrier to water security is the lack of municipal infrastructure to treat and distribute water to its dense population.
Zone Beta is in a state of hydrological equilibrium because high urban density creates surface runoff that naturally recharges local aquifers, balancing the low annual rainfall.
