Hydrology EESC BC 3025

Water for the world

Introduction

for most terrestrial life forms, water determines where they may live; man is exception

literally "water science," encompasses the study of the occurrence and movement of water on and beneath the surface of the Earth
finite though renewable resource

finite in quantity, unlimited in supply, use rate is limited by 'recycling times'

ancient Arabian wells, the Persian kanats, the Egyptian and Mesopotamian irrigation projects, the Roman aqueducts, and the Chinese irrigation systems, canals, and flood control works
Vitruvius, writing during the second half of the first century BC, often is credited with first recognizing that groundwater is derived primarily from infiltration of rain and snowmelt, rather than upwelling of subterranean water from great depths
Leonardo da Vinci wrote what is likely the earliest complete statement of the hydrological cycle (da Vinci CD)
since 1950s, more rigorous mathematical treament of the subject
20th century has seen most extensive manipulation of water, dams, groundwater schemes
13% of global riverflow is now controlled by mankind!
solutions to problems involving water supply, flood control, water quality control, recreation, and navigation require an understanding of hydrology

the fraction of renewable freshwater resources withdrawn on an annual basis is approximately 18%.
case study: Water use in the United States, 1990 Distribution of the use (Fig) (Where is groundwater important?)
sources, use and disposition of freshwater in the US (Fig)
Trends in population and freshwater withdrawals by source, 1950-2000 (Fig)
Trends in total water withdrawals by water-use category, 1950-2000 (Fig)
case study: Trends in Water Use in the United States, 1950-1990
major issues: water quantity and quality

global concerns as expressed at the UN Water conference in Dublin, January 1992:

poor state of water resources assessment throughout most of the world
withdrawal rates approaching the renewal rate (Table)
increasing numbers of aquifers that are being exploited at rates exceeding their recharge rate
in 1990, 1.8 billion people still had no access to sanitation services, 1.3 billion people still lacked access to clean water (Fig)
increasing demand of water for food production (Fig)
increased posution of water resources
in the developing world 80% of all disease is waterborn!
fears of global warming
increasing pressure on resources
prospects of 'Water Wars'

many countries depend on other countries on water supply (Table) => great potential for wars

population growth: 1900: 1.5bill, 1990: 5bill, 2000: 6bill, 2025: 8.5bill
doubling time ~ 50 years
improvement in quality of life
expansion of cities and centralized sewerage
demand for more industrial, commercial, and agricultural products
basic metabolism: 1l/d
2/3rd of population live on less than 50 l/d/p
rural consumption less than 200 l/d/p globally
demand in cities: 300-600 l/d/p (NYC 1.1 bill gal/d, 7mill inhabitants -> ca 600 l/d/p)
4% of population consumed more than 300l/d/p in 1980, will be 17% by 2000

amounts of water used higher with older technologies, with heavy manufacturing industry, and in warmer climates
industrial use in Europe and North America as a whole may increase by only 20-30% during last 20y vs. 300-500% in developing countries

main user of water supplies, mostly for irrigation (Fig)
one t of grain, feeding 6 people for one year, requires 3200m³ of water
50% of world food production by value is grown on irrigated land, covers only 15% of cultivated land area
Asia contains three-quarters of the world's irrigated area (400 mill ha), mostly in river valleys
human population is similarly concentrated on those floodplains, and is both the driving force and the consequence of irrigated agriculture
irrigated agriculture expanded rapidly, doubled during last 30y
by the early part of 21st century, irrigated land will reach the environmental potential of 470 mill ha, then decline

Hydrologists are needed!!

what do hydrologists do? See the USGS Hydrology Primer for some additional information.

What is hydrology? USGS Hydrology Primer. Basic info about what hydrology is about and what hydrologists do.
Hornberger G.M. et al. (1998) Elements of Physical Hydrology, Chapter 1.
Jones, J.A.A. (1997) Global Hydrology. Addison Wesley Longman, Essex.
Estimated Use of Water in the United States, USGS web site
UNEP Vital Water Graphics
Leonardo da Vinci CD ROM, Bellevue, WA : Corbis, c1996. BARNARD N6923.L33 L36 1996g
Codex Leicester Exhibit at the American Museum of Natural History