HYDROLOGY

• Hydrology is the study of the movement, distribution, and quality of water throughout the Earth, including the hydrologic cycle, water resources and environmental watershed sustainability. A practitioner of hydrology is a hydrologist, working within the fields of either earth or environmental science, physical geography, geology or civil and environmental engineering

HYDROLOGIC CYCLE

BRANCHES OF HYDROLOGY• Chemical hydrology is the study of the chemical characteristics of

water.Ecohydrology is the study of interactions between organisms and the hydrologic cycle.Hydrogeology is the study of the presence and movement of ground water.Hydroinformatics is the adaptation of information technology to hydrology and water resources applications.Hydrometeorology is the study of the transfer of water and energy between land and water body surfaces and the lower atmosphere.Isotope hydrology is the study of the isotopic signatures of water.Surface hydrology is the study of hydrologic processes that operate at or near Earth's surface.

APPLICATIONS OF HYDROLOGY• Determining the water balance of a region. • Determining the agricultural water balance. • Designing riparian restoration projects. • Mitigating and predicting flood, landslide and drought

risk. • Real-time flood forecasting and flood warning. • Designing irrigation schemes and managing agricultural

productivity. • Part of the hazard module in catastrophe modeling. • Providing drinking water.

• Designing dams for water supply or hydroelectric power generation. • Designing bridges. • Designing sewers and urban drainage system. • Analyzing the impacts of antecedent moisture on sanitary sewer

systems. • Predicting geomorphological changes, such as erosion or

sedimentation. • Assessing the impacts of natural and anthropogenic environmental

change on water resources. • Assessing contaminant transport risk and establishing

environmental policy guidelines

APPLICATIONS OF HYDROLOGY

PRECIPITATION FORMS• PRECIPITATION Precipitation includes all forms of

moisture that fall to the earth’s surface, such as rain, drizzle, snow, and hail. Precipitation is observed and classified by form, type, intensity, and character

• PRECIPITATION FORM.—Precipitation form is the state that the moisture is in: liquid, freezing, or frozen. Liquid precipitation is any precipitation that falls as a liquid and remains liquid after striking an object, such as the earth’s surface or the skin of an aircraft. Rain and drizzle are the only two types of liquid precipitation

• Rain—Liquid precipitation that has a water droplet diameter of 0.02 inch (0.5 mm) or larger. If the water droplets freeze upon contact with a surface, the phenomenon is called freezing rain.

• Drizzle—Liquid precipitation that consists of very small and uniformly dispersed droplets of liquid water that appear to "float" while following air currents. Drizzle usually falls from low stratus clouds and is frequently accompanied by fog. A slow rate of fall and the small size of the droplets (less than 0.02 inch) distinguish drizzle from rain

PRECIPITATION FORMS

• Snow—Precipitation that consists of white or translucent ice crystals. In their pure form, the ice crystals are highly complex, hexagonal

• Snow Pellets/Small Hail—White, opaque, round (or occasionally conical) kernels of snow like consistency, 0.08 to 0.2 inch in diameter. They are crisp, easily compressible, and may rebound or burst upon striking a hard surface. Snow pellets occur almost exclusively in snow showers

PRECIPITATION FORMS

• Ice Pellets—Transparent or translucent particles of ice that are either round or irregular (rarely conical) and have a diameter of 0.2 inch or less.

• Hail—A clear to opaque ball of hard ice, ranging in diameter from 1/8 inch or so to 5 inches or larger. Hailstone size is measured and reported in inches, hailstones are usually compared to common objects when reported to the public by television or radio, such as pea size, walnut size, golf-ball size, baseball size, or softball size.

PRECIPITATION FORMS

• CYCLONIC PRECIPITATION• ANTI CYCLONIC PRECIPITATION• OROGRAPHIC PRECIPITATION• CONVECTIVE PRECIPITATION• FRONTAL (COLD & WARM ) PRECIPITATION• PRECIPITATION DUE TO TURBULENT ACCENT

TYPES OF PRECIPITATION

OROGRAPHIC PRECIPITATION

FRONTAL (COLD & WARM ) PRECIPITATION

CONVECTIVE PRECIPITATION

TROPICAL CYCLONIC PRECIPITATION

CYCLONIC PRECIPITATION

• Stratiform or dynamic precipitation occurs as a consequence of slow ascent of air in synoptic systems (on the order of cm/s), such as over surface cold fronts, and over and ahead of warm fronts. Similar ascent is seen around tropical cyclones outside of the eyewall, and in comma-head precipitation patterns around mid-latitude cyclones

• Convective rain, or showery precipitation, occurs from convective clouds, e.g., cumulonimbus or cumulus congestus. It falls as showers with rapidly changing intensity. Convective precipitation falls over a certain area for a relatively short time, as convective clouds have limited horizontal extent. Most precipitation in the tropics appears to be convective