Water Cycle and Storage Systems
Ever wondered where all the water on Earth actually goes? The water cycle operates as an open system, meaning energy and matter can enter and leave freely. Most of our planet's water sits in oceans (96.5%), whilst smaller amounts exist in ice sheets and groundwater aquifers (each about 1.74%).
Water balance is basically nature's accounting system - inputs like precipitation and evaporation must equal outputs like discharge and evapotranspiration (water loss through plants). When this balance tips, you get either water surplus (flooding) or water deficit (drought). Storage refers to the maximum water soil can hold before becoming saturated.
Human activities massively disrupt natural water flows. Urbanisation increases surface runoff whilst reducing infiltration, and deforestation cuts down on interception, leading to more evaporation. Even farming practices like ploughing can break up soil surfaces, affecting how water moves through the ground.
Feedback loops either amplify or balance these changes. Positive feedback enhances existing conditions (more heat = more evaporation), whilst negative feedback restores equilibrium. Understanding soil permeability helps predict whether water will flow through or run off the surface.
Quick Tip: Remember that hydrographs show how rivers respond to rainfall - flashy rivers have short lag times and high flood risk, whilst slow-response rivers have longer lag times and lower peak discharge.
