HYDROLOGY

• Hydraulics is the science that deals with the motion of liquids in relation to disciplines such as fluid mechanics and fluid dynamics.
• Hydrology is the science that deals with the occurrence, circulation and distribution of water of the earth and earth’s atmosphere.
• Hydrology As a branch of earth science, it is concerned with the water in streams and lakes, rainfall and snowfall, snow and ice on the land and water occurring below the earth’s surface in the pores of the soil and rocks.
• The planet earth is called as the water planet
• Water is the most abundant substance on earth, the principal constituent of all living things, and a major force constantly shaping the surface of the earth.
• Water is the earth's ability to support life is facilitated by the existence of water in its three states, as it serves as a climate stabilizer by absorbing and releasing energy during transitions between these phases
• Hydrologic Cycle is the water transfer cycle, which occurs continuously in nature.
• Hydrologic cycle is a conceptual model of how water moves around between the earth and atmosphere in different states as a gas, liquid or solid.
• Evaporation is the transfer of water from the surface of the earth to the atmosphere.
• Transpiration is the process of water vapor being emitted by plant leaves.
• Evapotranspiration is the total evaporation.
• Precipitation is the result when tiny condensation particles grow too large.
• Infiltration is the flow of water from the ground surface into the ground.
• Runoff is the quantity of water discharged in surface streams.
• Sublimation is the direct conversion from solid state to vapor state.
• Water Vapor is the primary form of atmospheric moisture.
• Condensation is the transition process from the vapor state to the liquid state.
• Usually, the water cycle is in balance, and the amount of precipitation falling will slowly soak into the ground and eventually reach the rivers.
• The hydrological cycle is a good example of a closed system
• The hydrological cycle is a good example of a closed system: the total amount of water is the same, with virtually no water added to or lost from the cycle.
• Human activities have the potential to lead to changes in this balance which will have knock on impacts.
• Air temperature, precipitation, soil moisture, and evapotranspiration are related through the balance of incoming and outgoing energy, in combination with water at the earth’s surface.
• A water balance can be established for any of earth’s surface by calculating the total precipitation input and the total of various outputs.
• The water-balance approach allows an examination of the hydrologic cycle for any period of time.
• The water balance is a method by which we can account for the hydrologic cycle of a specific area, with emphasis on plants and soil moisture.
• The water balance is defined by the general hydrologic equation, which is basically a statement of the law of conservation of mass as applied to the hydrologic cycle
• What is the water balance equation in simplest form?

  input - output = change in storage
• what is the water balance equation per time step?

  precipitation - ( input - output ) - evaporation = storages changes
• Water balances are usually calculated for a specific area, which is called the catchment area (also called as drainage basin, discharge area, precipitation area, and watershed)
• A catchment is defined as the area upstream from a certain point in the water course that contributes to flow when precipitation falls. The size of the catchment depends on where this point is located in the stream and its topography or altitude situation
• The area of the catchment is determined by the water divide.
• Water budget estimates the amount of water in each component of the water cycle.
• Water Inflow are Precipitation, Surface water flow into basin, Imported water, Ground water inflow
• Water Outflow are Evaporation, Evapotranspiration, Surface water outflow, Exported water, Ground water outflow
• Change in Water Storage are Snow pack, Unsaturated soil zone, Streams, rivers, reservoirs, Aquifers
• how many percent is the salt water in earth?

  97.2%
• how many percent is the fresh water?

  2.8%
• how much water is consumable by people?

  0.25%