Pure Water Pressure at a Height h Above Groundwater Table

Introduction:
When water rises above the groundwater table, capillary action occurs due to the attractive forces between the water molecules and the solid surfaces of the soil. This action results in the rise of water in small pores and spaces of soil which is called capillary rise. The pressure exerted by the water at a height h above the groundwater table is known as pure water pressure.

Factors Affecting Pure Water Pressure:
The pure water pressure at a height h above the groundwater table is affected by various factors. Some of these factors are:

1. Soil Type: The type of soil affects the capillary rise and, hence, the pure water pressure. The finer the soil particles, the greater the capillary rise and pure water pressure.

2. Water Content: The water content in the soil affects the capillary rise and pure water pressure. The greater the water content, the higher the pure water pressure.

3. Height of Water Table: The height of the groundwater table also affects the pure water pressure. The higher the water table, the higher the pure water pressure.

Calculation of Pure Water Pressure:
The pure water pressure at a height h above the groundwater table can be calculated using the following formula:

P = γh

Where,
P = pure water pressure
γ = specific weight of water
h = height of water above groundwater table

The specific weight of water is equal to the weight of water per unit volume. It is equal to 9.81 kN/m³ or 62.4 lb/ft³.

Conclusion:
In summary, pure water pressure is the pressure exerted by water at a height h above the groundwater table due to capillary action. The pure water pressure is affected by various factors such as soil type, water content, and height of the groundwater table. The calculation of pure water pressure can be done using the formula P = γh.