# Presentation: 358859

## Purpose

Increase the participants knowledge and understanding of the interaction between meteorology and hydrology in watersheds:
Increase participants understanding of the functional aspects of watersheds;
Enhance the participants knowledge of the capabilities, limitations, and applications of hydrologic/hydrometeorologic forecasting systems

**Increase the participants knowledge and understanding of the interaction between meteorology and hydrology in watersheds:**
**Increase participants understanding of the functional aspects of watersheds;**
**Enhance the participants knowledge of the capabilities, limitations, and applications of hydrologic/hydrometeorologic forecasting systems**

## In the end, it is intended that participants will understand the basics of the hydrologic forecast process, the assumptions in the process, and the responsibilities associated with interpreting and issuing the forecast.

## Hydrology

**... ****an earth science.  It encompasses the occurrence, distribution, movement, and properties of the waters of the earth and their environmental relationships." (Viessman, Knapp, Lewis, & Harbaugh, 1977 - **_**Introduction to Hydrology**_**, Harper & Row Publishers, New York)**

## History of Hydrology

- Early philosophers speculated on the hydrologic cycle:
- Homer believed that there existed large subterranean reservoirs that fed the rivers, seas, springs, and wells - *was he wrong?*
- Homer did understand the dependence of flow in the Greek aqueducts on conveyance and velocity!

## History, cont....

- In the first century B.C., Marcus Vitruvius in the treatise De Architectura Libri Decem (the engineers chief handbook), Vol. 8 _***hypothesized***_ that rain and snow falling in the mountains infiltrated into the earth’s surface and appeared in the lowlands as springs and streams.....

## Early Success.....

- 4000 B.C. The Egyptians built a dam on the Nile to allow barren lands to again be used for agricultural purposes.
- 1000’s of years later, a canal to carry fresh water from Cairo to Suez was built.
- Towns in Mesopotamia were protected by flooding from high earthen walls.

## Early Disputes and Rules

- The cities of Lagash and Umma of Mesopotamia have documented water disputes.
- The Romans decree:
*Ne quis aquam oletato dolo malo ubi publice saliet si quis oletarit sestertiorum X mila multa esto*
*It is forbidden to pollute the public water supply; any deliberate offender shall be punished by a fine of 10,000 sesterces!*

## Qualitative Understanding

- Near end of 15th century, Leonardo da Vinci and Bernard Palissy independently reached conclusions on the hydrologic cycle - based on a philosophical understanding.
- There was still a lack of _***quantitative***_ understanding of the hydrologic cycle.

## The 17th Century	

- Perrault, Mariotte, and Halley began quantitative measurements and applications
- Perrault measured rainfall and runoff over the Seine River drainage basin for ~ 3 years - he illustrated that rainfall WAS adequate in quantity to account for river flows
- Mariotte gauged the velocity of the flow in the River Seine and estimated flows by also estimating river cross sectional areas.
- Halley was an astronomer!  He estimated evaporation from the Mediterranean Sea and correlated it to river flows into the Med, concluding that river flows were sufficient enough to provide that volume of water.

## The 18th Century

- Bernoulli - famous for hydraulics and fluid mechanics - the piezometer, the pitot tube, and Bernoulli’s theorem.
- The Chezy formula (channel flow)

## The 19th Century

- Hagen-Poiseuille - capillary flow equation.
- Darcy’s - flow in porous media.
- Duptuit-Thien well formula.
- Manning - Open channel flow.
- Systematic stream gaging.
- Mostly empirical in nature.

## The 20th Century

- Government agencies began to develop programs!
- Rational analysis begins
- Sherman - Unit hydrograph theory
- Horton - infiltration theory
- Snyder - Unit Hydrograph
- Clark - Unit Hydrograph
- etc...........

## Relatively Speaking....

- Hydrology
- Hydrometeorology
- Forecasting.......
- still relatively young!

## Modern day

- Very computer and data intensive
- High tech instruments
- Scale issues
- Policy issues
- Decision Support
- Forecasting!

## Reasons to Forecast

- Drought Predictions
- Agriculture
- Flooding
- Warnings
- Decision Making

## Hydrometeorology

**... ****an interdisciplinary science involving the study and analysis of the interrelationships between the atmospheric and land phases of water as it moves through the hydrologic cycle." (Hydrometeorological Service Operations for the 1990's, Office of Hydrology, National Weather Service, NOAA, 1996).**

## HydrometeorologySimplification of the Links

**Hydrology**

**Engineering/Fluid**

**Mechanics**

- 

- In-depth hydrologic

- analysis

- 

- Execution of complex

- hydrologic models.

- Adjustment of

- model parameters, and

- the derivation of

- hydrologic forecasts for

- all

- time scales

- 

- Applied hydrologic

- research

- 

- Development and

- calibration of

- hydrologic models

- 

- Development of

- hydrologic applications

- procedures.

**Meteorology**

**Thermodynamics/atmospheric**

**physics orientation**

- 

- In-depth meteorological

- analysis

- 

- Weather forecast and

- warning operations

- 

- Climatological forecasting

- 

- Applied meteorological

- and climatological

- research.

- 

- Development and calibration

- of meteorological models

- 

- Development of

- meteorological applications

- and procedures.

**Hydrometeorology**

**Interdisciplinary**

**Orientation**

- 

- Assimilation/use of

- radar based

- precip. estimates

- 

- Production and/or

- use of

- QPF's and

- other

- hydromet.

- forecasts

- 

- Use of guidance

- (e.g. flash flood) in

- hydrologic warning

- operations

- 

- Use of soil moisture

- states from

- hydrologic model in

- atmospheric model

- 

- Applied

- hydrometeorological

- research.