Storage

STORAGE LEARNING OBJECTIVES

  • Understand the role of stored water below ground (saturated and unsaturated zones).

  • Recognize the importance of snow and ice as water stores.

  • Learn techniques for measuring water in snow, ice, and subsurface (soil moisture, groundwater).

  • Familiarity with estimating techniques for water storage in various forms.

WATER STORAGE CONCEPTS

Stored Water Definition

  • Stored water includes groundwater, soil moisture, snow, and ice.

  • Storage is dynamic, not static, with continuous movement in and out of storage areas.

Zones of Water Storage

  • Saturated Zone: Water exists below the water table, termed groundwater or phreatic zone.

  • Unsaturated Zone: Water is found above the water table, termed soil water or vadose zone.

WATER MOVEMENT

Flow Characteristics

  • Water moves vertically (infiltration) and horizontally through soil.

  • Infiltration rate depends on current soil moisture and soil’s ability to transmit water.

Soil Properties

  • Gravimetric Water Content: Mass of water per unit mass of dry soil.

  • Bulk Density: Ratio of mass of dry soil to total soil volume, influencing water retention.

  • Porosity: The volume fraction of pores in the soil, affecting storage capacity.

INFILTRATION AND CAPACITY

Infiltration Rate

  • Water infiltrates faster at the beginning, slowing to a steady rate once capacity is reached.

Hydraulic Conductivity

  • Determines water movement through soil; varies with soil type and structure (e.g., sandy loam vs. clay).

GROUNDWATER AND AQUIFERS

  • Aquifer: A geological formation that stores and allows the extraction of groundwater.

  • Aquitard: A geological layer that limits water movement and is less permeable than an aquifer.

GROUNDWATER AGEING TECHNIQUES

Methods of Ageing Groundwater

  • Tritium and CFC Dating: Use isotopes to determine flow rates and contamination levels.

  • Techniques assess contaminant movement and estimate groundwater's residence time.

SNOW AND ICE AS WATER STORES

Importance of Snow and Ice

  • Significant for water resources, especially in seasons affecting river flows (e.g., spring melts).

  • Snowmelt dynamics contribute to seasonal river flow variations.

Measurement Techniques

  • Snow Pillows: Record snow weight to estimate water equivalent.

  • Remote Sensing: Use thermal and microwave methods to detect snow cover and moisture.

WATER BALANCE

Significance in Hydrology

  • Storage plays a critical role in water quantity and quality, affecting nutrient cycles and leaching processes.

  • Timing of water release from storage critically influences hydrological processes.

CONCLUSION

  • Understanding the dynamics of water storage and its impacts are vital in managing water resources effectively.