WMO Criteria For Minimum Network Density
The World Meteorological Organisation (1976) has recommended the minimum network densities for general hydro-meteorological practices.
For plain regions of temperate Mediterranean and tropical zones one station for 600-900 sq. km.
For mountainous region of temperate Mediterranean and tropical zones one station for 100-25 sq. km.
For arid and polar region one station for 1,500-10,000 sq. km.
Source: Guide to Hydrological Practices, Volume-I: “Hydrology - From Measurement to Hydrological Information”,
WMO No. 168