Hydrology PDF

HYDROLOGY passive process that is mostly regulated by soil  Hydrology is the study of water science. moisture content and atmospheric humidity.  Examines the distribution, occurrence, and  Just 1...

HYDROLOGY passive process that is mostly regulated by soil  Hydrology is the study of water science. moisture content and atmospheric humidity.  Examines the distribution, occurrence, and  Just 1% of the water that transpires through a circulation of water on Earth and in the Earth's plant is utilized by the plant to grow. 99 percent atmosphere. of it is released into the atmosphere.  It deals with water found in lakes and streams,  Evapotranspiration is the combined precipitation and snowfall, snow and ice on the components of evaporation and transpiration, ground, and water found in the pores of rocks and is sometimes used to evaluate the and soil. movement of water in the atmosphere.  An interdisciplinary field that draws on a variety CONDENSATION of related sciences, including meteorology,  The process that turns water vapor into a liquid geology, statistics, chemistry, physics, and fluid state is called condensation. Condensation in mechanics. the atmosphere can manifest as dew or clouds. HYDROLOGIC CYCLE  This is also the mechanism by which water accumulates on the exterior of a can or bottle of non-insulated cold beverage.  The air temperature and the dewpoint temperature are the two temperatures that determine condensation, not a single temperature. The temperature at which dew can form is known as the "dew point," which also happens to be the point at which air gets saturated and loses its ability to hold water vapor. Water vapor condenses with any further cooling. EVAPORATION PRECIPITATION  Evaporation is the process through which an  Any liquid or frozen water that condense in the element or compound changes from a liquid to atmosphere and returns to the earth is called a gaseous state below the boiling point; in the precipitation. It can take on various forms, such context of the water cycle, this process is as snow, sleet, and rain. specifically how liquid water enters the  Even in cases where the water came from the atmosphere as water vapor. ocean, precipitation is always fresh water. This  The humidity of the air is restored by is because water does not cause sea salt to evaporation. It plays a significant role in the evaporate. Water droplets can, however, energy exchange that generates atmospheric occasionally become contaminated by airborne motion, which in turn determines weather and pollutants before they hit the ground. climate in the Earth-atmosphere system.  Acid rain is the term for the precipitation that  Temperature, relative humidity, wind speed, arises from this. Although acid rain does not and solar radiation are the primary factors directly harm people, it can increase the acidity influencing evaporation. of lakes and streams. Because plants and  Ninety percent of the water in the atmosphere animals frequently cannot adapt to the acidity, comes from evaporation, with the other 10% this damages aquatic ecosystems coming from the release of water vapor by plant RUNOFF leaves  Runoff refers to precipitation that reached areas TRANSPIRATION where water collects from the ground surface  The process by which water leaves plant without being absorbed into the soil or through their stomata is called transpiration. On evaporating. In addition to causing erosion, the underside of leaves, stomata are tiny holes runoff transports materials from the ground's that connect to the vascular tissues of plants. surface to the rivers where the water ends up. For the majority of plants, transpiration is a Additionally, it may pollute water. Gette 1   Merely 35 percent of precipitation finds its way STORAGE into the ocean or sea. The soil absorbs the  The planet's atmosphere contains water that remaining 65%. A portion of it also evaporates. can be transported across its surface rather INFILTRATION PERCOLATION quickly The geologic characteristics of the soil Infiltration and percolation are two related but different and rock types found at the storage sites have a processes describing the movement of water through significant impact on the types of storage that soil. Infiltration is defined as the downward entry of take place both above and below ground. water into the soil or rock surface and percolation is the Oceans, lakes, reservoirs, and glaciers are flow of water through soil and porous or fractured rock examples of surface storage; soil, aquifers, and the fissures in rock formations are examples of underground storage These terms should not be used synonymously with permeability. Permeability is the property or capacity of a porous rock, sediment, or soil for transmitting a fluid. Essentially, permeability is how well water can flow through a material, while percolation and infiltration are the rates at which water can travel through materials. WATER BUDGET  One hydrological tool for measuring the amount of water entering and leaving a system is a water budget. To put it another way, it is a list of all the water that is exchanged and stored in the MAJOR COMPONENTS atmosphere (precipitation, evaporation), subsurface (aquifer, groundwater), and land Transportation Components Storage Components surface (rivers, lakes). Precipitation  The idea behind a water budget is that the Storage on Land Surface Evaporation amount and rate at which water enters and Transpiration Soil / Moisture Storage exits a region balances the rate of change of Infiltration water stored in that region. Hydrological Runoff Groundwater Storage engineers use this idea as the cornerstone for efficient management, planning, and sustainability of water resources. 𝐼𝑛𝑓𝑙𝑜𝑤 = 𝑂𝑢𝑡𝑓𝑙𝑜𝑤 ± 𝐶ℎ𝑎𝑛𝑔𝑒𝑠 𝑖𝑛 𝑆𝑡𝑜𝑟𝑎𝑔e Gette 2 WATER BUDGET EQUATION Table 1 – Estimated World Water Quantities The continuity equation for water in its different phases for a given area, let's say a catchment, over a period of time is expressed as 𝑴𝒂𝒔𝒔 𝒊𝒏𝒇𝒍𝒐𝒘 − 𝒎𝒂𝒔𝒔 𝒐𝒖𝒕𝒇𝒍𝒐𝒘 = 𝒄𝒉𝒂𝒏𝒈𝒆𝒔 𝒊𝒏 𝒎𝒂𝒔𝒔 𝒔𝒕𝒐𝒓𝒂𝒈𝒆 If the mass storage volumes, outflow volume, and inflow volume have the same density 𝑽𝐢 − 𝑽𝐨 = 𝑺 Rainfall – runoff relation Table 2 – Global Annual Water Balance 𝑹=𝑷–L 𝑷−𝑹−𝑮−𝑬−𝑻=𝑺 Wherein: P – precipitation R – surface runoff G – net groundwater flow out of the catchment E – evaporation T – transpiration ∆ 𝑆 – change in storage APPLICATION IN ENGINEERING Storage 𝑺 = 𝑺𝒔 + 𝑺𝒔𝒎 + 𝑺𝒈 Wherein: 𝑆𝑠 – surface water storage 𝑆𝑠𝑚 – water in storage as soil moisture 𝑆𝑔 – water in storage as groundwater Residence Time The design and administration of water resources Average duration of stay of a particle of water in a engineering projects heavily depend on hydrology, which reservoir has an impact on a number of crucial areas including 𝑻𝒓 = 𝑽/𝑸 irrigation systems, municipal water supply, flood control Wherein: systems, hydroelectric power generation, and 𝑽 – volume of water navigation infrastructure. Engineers and planners can 𝑸 – average flowrate maximize the sustainability and efficiency of these projects by using hydrological principles. This ensures WORLD WATER BALANCE that water resources are managed effectively to meet It is estimated that there are 1386 million cubic present and future needs while minimizing potential kilometers of water in the world. The oceans hold 96.5% risks and environmental impacts. of this water in the form of saline water. A portion of the water on land, or roughly 1% of the total water, is saline as well. As a result, there is only roughly 35.0 million 𝑘𝑚3 of fresh water accessible. The remaining 24.4 million 𝑘𝑚3 are frozen as ice in the Polar Regions, on top of mountains, and on glaciers. Of this, about 10.6 million cubic kilometers are both liquid and fresh. Gette 3