This document discusses environmental engineering topics related to water demand and the hydrologic cycle. It defines key terms for measuring water demand such as total annual volume, average daily rate of draft, and per capita demand. It also outlines the major processes in the hydrologic cycle, including evaporation, transpiration, condensation, precipitation, infiltration, percolation, and runoff. Finally, it briefly mentions rainwater harvesting.

1. Environmental Engineering I
CE 331

2. Overview
•Water Demand
•Hydrological Cycle
•Source of water

3. Water Demand
• Total annual volume in liters or million liters.
• Annual Average rate of draft in liters per day, (V/365).
• Average rate of draft in liters per day per person (liters per
capita day or lcpd), called per capita demand (q).
• Fluctuations in flows expressed in terms of % ratios of maximum
or minimum yearly, monthly, daily or hourly rates to their
corresponding average values.

4. Water Demand
• Domestic water demand
• Industrial water demand
• Institutional and Commercial water demand
• Demand for public use
• Fire demand

5. World Water Distribution

6. Hydrologic Cycle/Water Cycle
• Terrestrial Ecosystem
• Aquatic Ecosystem
• Flows of water
• Human Activities

7. Hydrologic Cycle

8. Water Cycle
• Evaporation: Conversion from liquid to vapor.
• Transpiration: Evaporation of water from leaves.
• Condensation: Conversion of vapor to liquid.
• Precipitation: Movement as rain, sleet, hail and snow.
• Infiltration: Movement into soil.
• Percolation: Downward flow through soil to aquifer.
• Runoff: Surface flow down slope to ocean, river or lake.

10. Rainwater Harvesting