Deficits in the Hydrological Cycle

Over-abstraction: The excessive removal of water from rivers and aquifers for irrigation or urban use faster than it can be recharged. This artificially creates a hydrological drought even during periods of normal rainfall.

Deforestation: Removing vegetation reduces the land's ability to intercept water and hold it in the soil. This increases surface runoff and reduces the amount of water that percolates down to recharge groundwater stores.

Climate Change: Increased greenhouse gas emissions lead to higher global temperatures, which accelerate evaporation rates and alter the frequency and intensity of ENSO cycles.

Forest Stress: Drought leads to reduced transpiration, which in turn reduces local humidity and precipitation, creating a positive feedback loop that further dries the environment.

Wetland Degradation: As wetlands dry out, they lose their ability to filter water and provide habitat. In extreme cases, the drying of organic soils can lead to soil acidification and the release of stored carbon dioxide.

Resilience: This refers to the ability of an ecosystem to recover from a drought. High biodiversity and healthy soil structures increase resilience, while human degradation decreases it.

Identify the Phase: When analyzing a case study, always specify if the drought is meteorological, agricultural, or hydrological to show a deep understanding of the process.

Link the Scales: Connect local human actions (like over-grazing) to global atmospheric patterns (like El Niño) to demonstrate an understanding of multi-scalar influences.

Check the Feedback: Look for positive feedback loops in exam questions, such as how reduced vegetation leads to reduced rainfall, which then further reduces vegetation.

Avoid Generalizations: Do not simply say 'it stops raining.' Use technical terms like 'descending air,' 'high-pressure systems,' and 'reduced infiltration capacity.'