The document discusses various aspects of rainfall including:
1. It describes three main types of precipitation - rain, snow, and sleet - and the temperature conditions required for each.
2. Methods for measuring rainfall are outlined, including non-recording gauges and self-recording gauges like tipping buckets and weighing types.
3. Three methods for calculating average rainfall over an area are summarized: arithmetic mean, Thiessen polygon, and isohyetal methods. The Thiessen and isohyetal methods weight rainfall amounts based on each station's representative area.
The hydrological cycle describes the continuous movement of water on, above, and below the surface of the Earth. Water exists in three forms on Earth - liquid (oceans, lakes, rivers), solid (ice caps, glaciers, snow), and gas (water vapor in the air). The sun drives the hydrological cycle by evaporating water from the surface into the air as vapor, which rises and cools to form clouds. Precipitation occurs when clouds become heavy with water and it falls as rain or snow. Water also returns to the air through evaporation from soil and transpiration from plants. Water running on land and underground replenishes rivers, lakes, and groundwater in a constant cycle powered by energy from
This document discusses catchment areas and factors that affect runoff. It defines key terms like catchment area, runoff, and runoff coefficient. It describes 3 types of catchment areas and characteristics of catchment areas that can be good, average, or bad. The document lists 7 factors that affect runoff, including pattern of rainfall, catchment surface type, topography, area size and shape, vegetation, geology, and meteorology. It also discusses several methods to estimate runoff, such as empirical formulas, Strange's tables and curves, infiltration method, and the unit hydrograph approach.
The document discusses infiltration, which is the process of rainwater entering the soil. Infiltrated water first meets any soil moisture deficit and then percolates vertically downward towards the groundwater table. The infiltration capacity of soil is the maximum rate at which it can absorb water and is denoted by f. Actual infiltration (fa) depends on whether the rainfall intensity (i) is greater than or less than the infiltration capacity. Infiltration is measured using infiltrometers and is affected by soil properties and antecedent moisture conditions.
The document defines key terms related to watersheds and runoff. It explains that a watershed is an area of land that drains into a common body of water, while a river basin is made up of many watersheds draining into a river and its tributaries. Runoff is defined as the portion of precipitation that flows overland as surface runoff or subsurface flow instead of infiltrating the soil. The factors that affect the amount of runoff are described, including precipitation characteristics, catchment shape and size, topography, geology, meteorology, land use, and storage features.
Hydrological cycle- Meteorological measurements – Requirements, types and forms of Precipitation-Rain Gauges-Spatial analysis of rainfall data using Thiessen and Isohyetal methods Infiltration-Infiltration Index-Interception-Evaporation, Watershed, catchment and basin - Catchment characteristics - factors affecting runoff – Runoff estimation using empirical
When rainwater falls on the ground, a small part of it is initially absorbed by the top thin layer of soil so as to replenish the soil moisture deficiency.
This document discusses different types of runoff including surface runoff, subsurface runoff, and base flow. It explains factors that affect runoff such as climate, physiographic characteristics, soil properties, and land use. Several methods to compute runoff are presented, including the Rational Method, Cook's Method, and the Curve Number Method. Flow duration curves are also introduced to analyze stream flow variability over time.
This document provides an introduction to hydrology. It discusses the hydrologic cycle and its components like evaporation, transpiration, infiltration, etc. It also discusses different types of precipitation like rain, snow, drizzle and methods of precipitation classification. Measurement of rainfall using rain gauges and estimation of rainfall for areas between gauges using methods like arithmetic mean, Thiessen polygon and isohyetal maps are described. Optimum density of rain gauges for different terrains is also mentioned.
The hydrological cycle describes the continuous movement of water on, above, and below the surface of the Earth. Water exists in three forms on Earth - liquid (oceans, lakes, rivers), solid (ice caps, glaciers, snow), and gas (water vapor in the air). The sun drives the hydrological cycle by evaporating water from the surface into the air as vapor, which rises and cools to form clouds. Precipitation occurs when clouds become heavy with water and it falls as rain or snow. Water also returns to the air through evaporation from soil and transpiration from plants. Water running on land and underground replenishes rivers, lakes, and groundwater in a constant cycle powered by energy from
This document discusses catchment areas and factors that affect runoff. It defines key terms like catchment area, runoff, and runoff coefficient. It describes 3 types of catchment areas and characteristics of catchment areas that can be good, average, or bad. The document lists 7 factors that affect runoff, including pattern of rainfall, catchment surface type, topography, area size and shape, vegetation, geology, and meteorology. It also discusses several methods to estimate runoff, such as empirical formulas, Strange's tables and curves, infiltration method, and the unit hydrograph approach.
The document discusses infiltration, which is the process of rainwater entering the soil. Infiltrated water first meets any soil moisture deficit and then percolates vertically downward towards the groundwater table. The infiltration capacity of soil is the maximum rate at which it can absorb water and is denoted by f. Actual infiltration (fa) depends on whether the rainfall intensity (i) is greater than or less than the infiltration capacity. Infiltration is measured using infiltrometers and is affected by soil properties and antecedent moisture conditions.
The document defines key terms related to watersheds and runoff. It explains that a watershed is an area of land that drains into a common body of water, while a river basin is made up of many watersheds draining into a river and its tributaries. Runoff is defined as the portion of precipitation that flows overland as surface runoff or subsurface flow instead of infiltrating the soil. The factors that affect the amount of runoff are described, including precipitation characteristics, catchment shape and size, topography, geology, meteorology, land use, and storage features.
Hydrological cycle- Meteorological measurements – Requirements, types and forms of Precipitation-Rain Gauges-Spatial analysis of rainfall data using Thiessen and Isohyetal methods Infiltration-Infiltration Index-Interception-Evaporation, Watershed, catchment and basin - Catchment characteristics - factors affecting runoff – Runoff estimation using empirical
When rainwater falls on the ground, a small part of it is initially absorbed by the top thin layer of soil so as to replenish the soil moisture deficiency.
This document discusses different types of runoff including surface runoff, subsurface runoff, and base flow. It explains factors that affect runoff such as climate, physiographic characteristics, soil properties, and land use. Several methods to compute runoff are presented, including the Rational Method, Cook's Method, and the Curve Number Method. Flow duration curves are also introduced to analyze stream flow variability over time.
This document provides an introduction to hydrology. It discusses the hydrologic cycle and its components like evaporation, transpiration, infiltration, etc. It also discusses different types of precipitation like rain, snow, drizzle and methods of precipitation classification. Measurement of rainfall using rain gauges and estimation of rainfall for areas between gauges using methods like arithmetic mean, Thiessen polygon and isohyetal maps are described. Optimum density of rain gauges for different terrains is also mentioned.
This document describes the table method for estimating runoff. It involves using tables to determine peak runoff rates based on watershed characteristics like soil type, slope, and land cover. The tables are separated based on watershed shape - square, broad and short, or long and narrow. Users first determine the watershed characteristics score from Table 1, then find the peak discharge rate in the appropriate watershed shape table by matching the score and area. Two examples are provided to demonstrate calculating runoff rates using this method.
Hydrology and irrigation engineering cel 303Gaurav Mittal
This document summarizes information about infiltration, including definitions of key terms, factors that affect infiltration, and the infiltration capacity curve. It defines infiltration as the process by which water enters the soil surface and moves downward towards the water table. Key terms discussed include infiltration capacity, infiltration rate, field capacity, and equivalent moisture. Factors that influence infiltration include soil texture, crusting, compaction, organic matter, and pores. The infiltration capacity curve illustrates the relationship between infiltration rate and time during rainfall.
The document discusses infiltration, which is the process by which water enters soil. It defines infiltration as the rate at which soil can absorb rainfall or irrigation, measured in mm/hr or inches/hr. An infiltrometer is used to measure infiltration rates. The infiltration capacity depends on factors like the soil type and moisture level, with dry soil having a higher capacity than moist soil. Infiltration is important for understanding groundwater recharge and runoff. Other factors like vegetation cover, land use, temperature, and water quality can also impact infiltration rates.
This document discusses various methods for estimating runoff from rainfall. It begins by defining components of stream flow such as overland flow, interflow, and baseflow. It then discusses catchment characteristics and methods for classifying streams. Various factors that affect runoff are identified, including drainage area, soil type, land use, and antecedent moisture conditions. Two primary methods for estimating runoff are presented: the Rational Method and the SCS Curve Number Method. Worked examples are provided to demonstrate how to apply both methods to calculate peak runoff rates from given rainfall and catchment property data.
The document defines and discusses several terms related to hydrology:
1. Potamology is the study of rivers, which examines rivers from five perspectives including the physics of running water and rivers as habitats for organic life.
2. Limnology is the study of biological, chemical, and physical features of lakes and other bodies of fresh water.
3. Cryology is the scientific study of ice, including areas like snow and ice mapping and classification.
This document describes different types of infiltrometers used to measure infiltration rates of water into soil. A single ring infiltrometer consists of a metal cylinder driven into the ground filled with a fixed level of water. A double ring infiltrometer uses two concentric rings to better control lateral water flow. A rainfall simulator produces controlled rainfall over a plot of land to measure surface runoff under varying rainfall intensities and durations.
Runoff is that portion of the rainfall or irrigation water which leaves a field either as surface or as subsurface flow. When rainfall intensity reaching the soil surface is less than the infiltration capacity, all the water is absorbed in to the soil. As rain continues, soil becomes saturated and infiltration capacity is reduced, shallow depression begins to fill with water, then the overland flow starts as runoff.
Short power point made by AS/A Level students with the aim of explaining Storm Hydrographs and the foundations of the Drainage Basin Hydrological Cycle.
Hydrographs show variations in a river's discharge over time, usually during a rainstorm. The shape of a hydrograph is influenced by factors like land use, precipitation amounts, geology, and soil. A hydrograph has a rising limb as discharge increases and a falling limb as it decreases. Lag time is the delay between peak rainfall and peak discharge as water from precipitation moves through the landscape into the river. Urbanization can increase flooding risk by preventing water infiltration into paved surfaces.
Runoff computation by infiltration indicesSagar Vekariya
This document discusses methods for computing runoff using infiltration rates. It defines infiltration as the process by which water enters the soil, governed by gravity and capillary action. There are two key terms: infiltration capacity, which is the maximum rate of water entering soil in a given condition; and infiltration rate, which is the actual rate of water entering during a storm, equal to the capacity or rainfall rate, whichever is lower. There are two main methods for computing runoff - using an infiltration capacity curve, which plots capacity versus rainfall to determine excess rainfall/runoff; and infiltration indices, which provide average loss rates for larger catchment areas. Specific indices discussed are the W-Index and φ-Index. An example calculation is provided
Introduction, hydrologic cycle, climate and water m1Bibhabasu Mohanty
Introduction, Hydrologic cycle, Climate and water availability, Water balances,
Precipitation: Forms, Classification, Variability, Measurement, Data analysis, Evaporation and its measurement, Evapotranspiration and its measurement, Penman Monteith method. Infiltration: Factors affection infiltration, Horton’s equation and Green Ampt method.
The document discusses several key aspects of hydrology:
- Precipitation is the main driver of hydrologic processes and is formed as air cools and its ability to hold water decreases.
- Weather patterns result in different biomes and rainfall patterns across geographic regions.
- Water moves across and through soils via processes like infiltration, evaporation, transpiration, surface runoff, subsurface stormflow, and groundwater flow.
- The dominant runoff process depends on factors like rainfall intensity, soil saturation, and watershed characteristics, and can include Horton overland flow, saturation overland flow, or subsurface stormflow.
Hydrographs show changes in river discharge over time in response to rainfall. They are constructed by measuring river discharge during and after storms. A typical hydrograph has a rising limb as discharge increases, peaks at maximum discharge, then declines on the recession limb. Analysis of hydrographs can predict flooding and inform flood prevention. Characteristics like basin area, slope, soil, land use, and rainfall patterns influence a hydrograph's shape and timing.
This document discusses runoff and provides definitions, processes, types, factors affecting runoff, and methods to estimate runoff. It defines runoff as the portion of precipitation that flows towards rivers and oceans as surface or subsurface flow. The key types of runoff discussed are surface runoff, subsurface/interflow, and baseflow. Factors affecting runoff include precipitation characteristics, catchment characteristics, topography, geology, and storage features. Methods to estimate runoff include direct measurement and indirect methods like empirical formulas, the rational method, and unit hydrograph analysis.
Hydrology is the study of water on Earth. The key concepts discussed include:
1. The hydrological cycle which describes the continuous movement of water on, above, and below the surface of the Earth.
2. Drainage basins which are areas of land where water from rain or snowmelt drains into a body of water.
3. Factors that influence storm hydrographs such as rock types, basin characteristics, precipitation levels, temperature, and vegetation cover.
Runoff occurs when the rate of precipitation exceeds the rate at which water can infiltrate into the soil. There are several key factors that affect the amount of runoff from a catchment area, including: (1) precipitation characteristics such as type, duration, and intensity of rainfall; (2) the size, shape, and topography of the catchment area; and (3) the geological, meteorological, and surface characteristics of the catchment area such as soil type, slope, temperature, and land use. These factors influence how much water is able to infiltrate versus flowing across the surface as runoff.
Baseflow, also known as drought flow or low-water discharge, is the portion of streamflow that comes from deep subsurface flow and delayed shallow subsurface flow, rather than surface runoff or direct groundwater flow. Certain parameters of baseflow can describe the mixing of waters like precipitation and groundwater in catchments and the level of groundwater contribution to streamflow. Baseflow separation is a common method used to determine what portion of a streamflow hydrograph occurs from baseflow versus overland flow, using techniques like isotope tracing and the HYSEP software program.
The document discusses infiltration, percolation, and factors that influence infiltration rates in soils. It describes how infiltration rates are measured and defines key terms like infiltration rate, hydraulic conductivity, and percolation. Soil texture, structure, and the presence of vegetation can greatly impact infiltration. Higher infiltration is associated with larger soil pores, continuous pore networks, and protective vegetative covers on the soil surface.
This document provides an overview of Module 1 of the Advanced Hydrology course. The objective of Module 1 is to introduce the phenomena of weather, the hydrologic cycle, and hydrologic losses/measurements. The module will cover topics like weather, the different stages of the hydrologic cycle, hydrologic losses, and analytical and empirical measurement methods. The first lecture will cover weather, the atmospheric layers, wind belts, cloud types, precipitation events, and factors affecting the Indian climate and its seasons.
The document discusses hydrology and the hydrologic cycle. It begins by defining hydrology as the science of water and its movement on the Earth. It then describes the key components of the hydrologic cycle, including evaporation, precipitation, infiltration, transpiration, and the various stages water passes through as it circulates from the oceans to the atmosphere and back again. Engineering applications of hydrology are also mentioned such as flood control and selecting dam sites. Measurement of rainfall is discussed, along with different types of rain gauges used to collect precipitation data.
Precipitation is the natural process of conversion of atmospheric water vapour into water. The water falls(comes down) in the form of a rainfall or snow fall. The term precipitation is also used to refer rainfall. It is term and includes all forms of falling moisture viz., rainfall, snowfall, sleet, hail etc. Rainfall occurs in the form of a pattern.
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This document describes the table method for estimating runoff. It involves using tables to determine peak runoff rates based on watershed characteristics like soil type, slope, and land cover. The tables are separated based on watershed shape - square, broad and short, or long and narrow. Users first determine the watershed characteristics score from Table 1, then find the peak discharge rate in the appropriate watershed shape table by matching the score and area. Two examples are provided to demonstrate calculating runoff rates using this method.
Hydrology and irrigation engineering cel 303Gaurav Mittal
This document summarizes information about infiltration, including definitions of key terms, factors that affect infiltration, and the infiltration capacity curve. It defines infiltration as the process by which water enters the soil surface and moves downward towards the water table. Key terms discussed include infiltration capacity, infiltration rate, field capacity, and equivalent moisture. Factors that influence infiltration include soil texture, crusting, compaction, organic matter, and pores. The infiltration capacity curve illustrates the relationship between infiltration rate and time during rainfall.
The document discusses infiltration, which is the process by which water enters soil. It defines infiltration as the rate at which soil can absorb rainfall or irrigation, measured in mm/hr or inches/hr. An infiltrometer is used to measure infiltration rates. The infiltration capacity depends on factors like the soil type and moisture level, with dry soil having a higher capacity than moist soil. Infiltration is important for understanding groundwater recharge and runoff. Other factors like vegetation cover, land use, temperature, and water quality can also impact infiltration rates.
This document discusses various methods for estimating runoff from rainfall. It begins by defining components of stream flow such as overland flow, interflow, and baseflow. It then discusses catchment characteristics and methods for classifying streams. Various factors that affect runoff are identified, including drainage area, soil type, land use, and antecedent moisture conditions. Two primary methods for estimating runoff are presented: the Rational Method and the SCS Curve Number Method. Worked examples are provided to demonstrate how to apply both methods to calculate peak runoff rates from given rainfall and catchment property data.
The document defines and discusses several terms related to hydrology:
1. Potamology is the study of rivers, which examines rivers from five perspectives including the physics of running water and rivers as habitats for organic life.
2. Limnology is the study of biological, chemical, and physical features of lakes and other bodies of fresh water.
3. Cryology is the scientific study of ice, including areas like snow and ice mapping and classification.
This document describes different types of infiltrometers used to measure infiltration rates of water into soil. A single ring infiltrometer consists of a metal cylinder driven into the ground filled with a fixed level of water. A double ring infiltrometer uses two concentric rings to better control lateral water flow. A rainfall simulator produces controlled rainfall over a plot of land to measure surface runoff under varying rainfall intensities and durations.
Runoff is that portion of the rainfall or irrigation water which leaves a field either as surface or as subsurface flow. When rainfall intensity reaching the soil surface is less than the infiltration capacity, all the water is absorbed in to the soil. As rain continues, soil becomes saturated and infiltration capacity is reduced, shallow depression begins to fill with water, then the overland flow starts as runoff.
Short power point made by AS/A Level students with the aim of explaining Storm Hydrographs and the foundations of the Drainage Basin Hydrological Cycle.
Hydrographs show variations in a river's discharge over time, usually during a rainstorm. The shape of a hydrograph is influenced by factors like land use, precipitation amounts, geology, and soil. A hydrograph has a rising limb as discharge increases and a falling limb as it decreases. Lag time is the delay between peak rainfall and peak discharge as water from precipitation moves through the landscape into the river. Urbanization can increase flooding risk by preventing water infiltration into paved surfaces.
Runoff computation by infiltration indicesSagar Vekariya
This document discusses methods for computing runoff using infiltration rates. It defines infiltration as the process by which water enters the soil, governed by gravity and capillary action. There are two key terms: infiltration capacity, which is the maximum rate of water entering soil in a given condition; and infiltration rate, which is the actual rate of water entering during a storm, equal to the capacity or rainfall rate, whichever is lower. There are two main methods for computing runoff - using an infiltration capacity curve, which plots capacity versus rainfall to determine excess rainfall/runoff; and infiltration indices, which provide average loss rates for larger catchment areas. Specific indices discussed are the W-Index and φ-Index. An example calculation is provided
Introduction, hydrologic cycle, climate and water m1Bibhabasu Mohanty
Introduction, Hydrologic cycle, Climate and water availability, Water balances,
Precipitation: Forms, Classification, Variability, Measurement, Data analysis, Evaporation and its measurement, Evapotranspiration and its measurement, Penman Monteith method. Infiltration: Factors affection infiltration, Horton’s equation and Green Ampt method.
The document discusses several key aspects of hydrology:
- Precipitation is the main driver of hydrologic processes and is formed as air cools and its ability to hold water decreases.
- Weather patterns result in different biomes and rainfall patterns across geographic regions.
- Water moves across and through soils via processes like infiltration, evaporation, transpiration, surface runoff, subsurface stormflow, and groundwater flow.
- The dominant runoff process depends on factors like rainfall intensity, soil saturation, and watershed characteristics, and can include Horton overland flow, saturation overland flow, or subsurface stormflow.
Hydrographs show changes in river discharge over time in response to rainfall. They are constructed by measuring river discharge during and after storms. A typical hydrograph has a rising limb as discharge increases, peaks at maximum discharge, then declines on the recession limb. Analysis of hydrographs can predict flooding and inform flood prevention. Characteristics like basin area, slope, soil, land use, and rainfall patterns influence a hydrograph's shape and timing.
This document discusses runoff and provides definitions, processes, types, factors affecting runoff, and methods to estimate runoff. It defines runoff as the portion of precipitation that flows towards rivers and oceans as surface or subsurface flow. The key types of runoff discussed are surface runoff, subsurface/interflow, and baseflow. Factors affecting runoff include precipitation characteristics, catchment characteristics, topography, geology, and storage features. Methods to estimate runoff include direct measurement and indirect methods like empirical formulas, the rational method, and unit hydrograph analysis.
Hydrology is the study of water on Earth. The key concepts discussed include:
1. The hydrological cycle which describes the continuous movement of water on, above, and below the surface of the Earth.
2. Drainage basins which are areas of land where water from rain or snowmelt drains into a body of water.
3. Factors that influence storm hydrographs such as rock types, basin characteristics, precipitation levels, temperature, and vegetation cover.
Runoff occurs when the rate of precipitation exceeds the rate at which water can infiltrate into the soil. There are several key factors that affect the amount of runoff from a catchment area, including: (1) precipitation characteristics such as type, duration, and intensity of rainfall; (2) the size, shape, and topography of the catchment area; and (3) the geological, meteorological, and surface characteristics of the catchment area such as soil type, slope, temperature, and land use. These factors influence how much water is able to infiltrate versus flowing across the surface as runoff.
Baseflow, also known as drought flow or low-water discharge, is the portion of streamflow that comes from deep subsurface flow and delayed shallow subsurface flow, rather than surface runoff or direct groundwater flow. Certain parameters of baseflow can describe the mixing of waters like precipitation and groundwater in catchments and the level of groundwater contribution to streamflow. Baseflow separation is a common method used to determine what portion of a streamflow hydrograph occurs from baseflow versus overland flow, using techniques like isotope tracing and the HYSEP software program.
The document discusses infiltration, percolation, and factors that influence infiltration rates in soils. It describes how infiltration rates are measured and defines key terms like infiltration rate, hydraulic conductivity, and percolation. Soil texture, structure, and the presence of vegetation can greatly impact infiltration. Higher infiltration is associated with larger soil pores, continuous pore networks, and protective vegetative covers on the soil surface.
This document provides an overview of Module 1 of the Advanced Hydrology course. The objective of Module 1 is to introduce the phenomena of weather, the hydrologic cycle, and hydrologic losses/measurements. The module will cover topics like weather, the different stages of the hydrologic cycle, hydrologic losses, and analytical and empirical measurement methods. The first lecture will cover weather, the atmospheric layers, wind belts, cloud types, precipitation events, and factors affecting the Indian climate and its seasons.
The document discusses hydrology and the hydrologic cycle. It begins by defining hydrology as the science of water and its movement on the Earth. It then describes the key components of the hydrologic cycle, including evaporation, precipitation, infiltration, transpiration, and the various stages water passes through as it circulates from the oceans to the atmosphere and back again. Engineering applications of hydrology are also mentioned such as flood control and selecting dam sites. Measurement of rainfall is discussed, along with different types of rain gauges used to collect precipitation data.
Precipitation is the natural process of conversion of atmospheric water vapour into water. The water falls(comes down) in the form of a rainfall or snow fall. The term precipitation is also used to refer rainfall. It is term and includes all forms of falling moisture viz., rainfall, snowfall, sleet, hail etc. Rainfall occurs in the form of a pattern.
very nice and amazingnsnznznzjzjzjzjznznznnzznznznznznznnznznsnznznznznznzznnsnzsnnznznznznznznzjznsnzjsnsnzifnekaolNcnfekaoLmxfnfbkslks siwnd siw sbxhw sus w by sq sbsjdjzixns js wis js wjz sus sbxis jswb sus s sjcne sjs s sjz w aix w sjz sjz s wuz d eusnd sj xxjbs sus ebsbe dhs dhssssssbs dbs shs dbd snz shs s sjs snsb snsjs shs sns sjsbjz wus shx sus shs xh shz shs shs shs shs hs shs shs ßhs sjnshs sjsnsjsnhssnhsdbwbe dhsndj shd shd ujsnsid sjsndjd sjsnxbsbs bs dnx s him sjs xbs sh sndsbs shsnsbs sz
Rainfall occurs when water vapor in the atmosphere condenses into droplets. The water cycle describes the process by which water evaporates from bodies of water, rises into the sky as vapor to form clouds, condenses into rain or other precipitation and falls back to earth. Rain is measured using rain gauges, which collect rainfall and some record amounts electronically or on charts driven by clockwork mechanisms. The document discusses different rain intensities, types of rainfall formation, and factors that influence rainfall amounts.
The term precipitation is also used to refer all forms of falling moisture viz., rainfall, snowfall, sleet, hail etc. Rainfall occurs in the form of a pattern. Atmospheric Precipitation is a wonderful process for the whole globe to use. This module explains it in general.
This document discusses different types of precipitation and the hydrological cycle. It begins by explaining the hydrological cycle and its key stages: evaporation, sublimation, condensation, precipitation, infiltration, and runoff. It then defines precipitation and describes different forms it can take including rain, snow, drizzle, freezing rain, sleet, hail, and others. Finally, it outlines three main types of precipitation: cyclonic (including frontal and non-frontal), convective, and orographic precipitation.
Hydrology is the study of water on Earth. The hydrologic cycle describes how water circulates between the atmosphere, land, and oceans through various stages like evaporation, transpiration, precipitation, and subsurface flow. Precipitation occurs in forms like rain, snow, sleet, and hail. In India, rainfall patterns vary between the monsoon, post-monsoon, winter, and summer periods. Rainfall is measured using rain gauges, which collect water and can be non-recording or recording types like tipping buckets or weighing gauges. Factors like landscape, climate, and human activities influence the distribution and movement of water across environments.
Precipitation occurs when moisture from the atmosphere reaches the Earth's surface. There are several types of precipitation including rain, snow, hail, fog, dew, mist, glaze, rime, and sleet. Precipitation forms through convectional, orographic, and cyclonic/frontal mechanisms. Rainfall and snowfall are most commonly measured using non-recording and recording rain gauges, which collect precipitation and allow measurement of amount, intensity, and duration. Proper siting and placement of rain gauges is important to obtain accurate precipitation measurements.
This document discusses different types of rainfall including artificial rainfall, convective rainfall, orographic rainfall, frontal rainfall, and cyclonic rainfall. It provides details on the stages and processes involved in artificial rainfall (cloud seeding). It describes convective rainfall as occurring from heated air in equatorial regions leading to rapid showers. Orographic rainfall is explained as air forced upwards over mountains, cooling and condensing into rain. Frontal rainfall involves warm air rising over cold air at fronts, cooling and producing clouds and rain. Cyclonic rainfall occurs along fronts formed by different air masses meeting in temperate depressions.
The document discusses the hydrologic cycle and precipitation. It defines the hydrologic cycle as the continuous process by which water evaporates from bodies of water into the atmosphere, condenses into clouds, and falls back to the Earth's surface as precipitation such as rain, snow, sleet or hail. It then describes the different forms and types of precipitation, including liquid precipitation like rain and drizzle, frozen precipitation like sleet and hail, and types like cyclonic, convective, and orographic precipitation. Finally, it discusses characteristics of rainfall such as size, shape, intensity and duration.
This document discusses different types of rainfall including artificial/cloud seeding rainfall, convective rainfall, orographic rainfall, frontal rainfall, and cyclonic rainfall. It provides details on the formation process for each type. Artificial rainfall involves using chemicals to stimulate condensation and seed clouds. Convective rainfall occurs from heating of the earth's surface and rapid changes in intensity. Orographic rainfall is caused when air is forced upwards over mountains, cooling and condensing. Frontal rainfall occurs when warm and cold air masses meet along a front. Cyclonic rainfall is associated with low pressure systems and occurs along fronts with the meeting of different air masses.
Hydrology is the science of water on Earth. It studies the occurrence, circulation, and distribution of water, including precipitation, evaporation, soil moisture, groundwater, runoff, and flooding. There are two main types - scientific hydrology which studies physical processes, and engineering hydrology which applies scientific principles to water resources. The hydrologic cycle describes the continuous movement of water on, above, and below the surface of the Earth, including storage and transport through different physical states driven by energy from the sun.
Precipitation occurs in solid or liquid forms when water vapor condenses and falls from clouds to the ground. The main types of precipitation are snow, hail, and rain. Snow forms when water vapor sublimates directly to snowflakes below freezing. Hail forms when water droplets are carried to high altitudes by updrafts and freeze into layers around a snow or ice core. Rain forms through condensation and falling water droplets. Precipitation affects ecosystems, economies, and transportation.
This document discusses various types and aspects of precipitation. It defines precipitation as moisture falling from clouds to the ground, including rainfall, snowfall, hail, frost and dew. It describes the key factors required for precipitation to form and different types including convective, frontal, orographic and cyclonic precipitation. It also discusses methods of measuring and analyzing precipitation data.
This document summarizes key concepts in agricultural meteorology, including:
1. The composition of the atmosphere, with nitrogen, oxygen, argon, and carbon dioxide as the principal gases.
2. The physical structure of the atmosphere, describing the troposphere, stratosphere, mesosphere, thermosphere, and exosphere based on vertical temperature variation.
3. Key concepts around atmospheric humidity including specific humidity, absolute humidity, mixing ratio, and relative humidity. It also describes evapotranspiration and the factors that influence it.
4. The different forms of precipitation including rain, snow, hail, sleet, and glaze. It also summarizes condensation and the various forms
The document summarizes the hydrologic cycle, which is the continuous movement of water on, above, and below the surface of the Earth. It involves processes such as evaporation, transpiration, condensation, precipitation, infiltration, and runoff. Water circulates as vapor between the atmosphere and land and oceans, driven by energy from the sun. It discusses the major reservoirs of water on Earth and the percentages of freshwater and saltwater they contain. It also explains the processes involved in the hydrologic cycle in detail through diagrams and descriptions.
This document discusses precipitation, including its definition, forms, measurement, and classification. It defines precipitation as moisture deposits from the troposphere to the ground. The main forms of precipitation include rain, snow, hail, sleet, fog, frost, and drizzle. Precipitation occurs through lifting of air masses, condensation, growth of cloud droplets, and accumulation of moisture. It can be classified as convective, orographic, or cyclonic based on the lifting mechanism. Precipitation is primarily measured using rain gauges, radar, and satellites. Networks of precipitation measurement stations are designed for purposes like water resource management and flood forecasting.
This document provides an overview of hydrology and the hydrologic cycle. It begins with an introduction to water as a natural resource and the role of hydrology in understanding water systems. It then defines hydrology as the science dealing with the occurrence, circulation, and distribution of water on Earth. The main components of the hydrologic cycle are described as evaporation, transpiration, precipitation, and runoff. The document discusses different forms of precipitation including rain, snow, hail, sleet, and drizzle. It also covers terms related to rainfall such as intensity, daily rainfall, mean annual rainfall, isohyets, and catchment area. Measurement of rainfall using non-recording and recording rain gauges is briefly explained
1) Water exists in the atmosphere in solid, liquid, and gaseous forms. Water vapor accounts for around 4% of the atmosphere and plays an important role in determining weather through condensation and precipitation.
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3. 3
CONTENTS:
Measurement of Rain fall
Methods of Calculating average Rainfall
Evaporation [E]
Transpiration [T]
Evapotranspiration [ET]
Runoff
Runoff Calculations
4. 4
From where the Earth water arrives ?
If you consider that Helium is very much not
reactive could not a real surprise that an element
built on Hydrogen and Oxygen is abundant on
the Earth.
Introduction :
5. 5
Water is the most important resource of any
country, and of the entire society as a whole,
since no life is possible without water. It has
this unique position among other natural
resources, because the country can survive in
the absence of the other resources except this
one.
Introduction :
6. 6
Distribution of Water on Earth
Soil moisture is 0.001% of all water.
Provides for all agricultural food production and
sustains all terrestrial ecosystems
Introduction :
7. 7
The hydrological cycle is the circulation of water
evaporated from the sea and land surfaces, its
transport through the atmosphere to the land
and its return to the sea via surface,
subsurface and atmospheric routes.
Hydrologic cycle:
9. 9
The flows from the atmosphere to the surface of
the Earth are called precipitations.
The water that reaches the ground can infiltrate
and flow within the soil or it can run off on the
surface (these are referred to as horizontal
flows).
Hydrologic cycle:
13. 13
Types of Precipitation :
Precipitation Starts With Different
Air Masses Being Pushed Around by Global
Winds
High pressured
air mass
Cold air mass
Wet, humid air
mass
Warm, Dry air
mass
Low pressured
air mass
Obviously, these moving air masses will eventually bump into one another.
14. 14
When 2 or more different air
masses meet, the place where
they bump is called… Front
A storm, usually with precipitation, occurs at this front.
15. 15
The type of precipitation
that falls from the clouds
to the surface of the
Earth depends on ONE
main thing…
TEMPERATURE
The temperature of the clouds vs. the temperature of
the surface air.
16. 16
RAIN
Rain occurs when precipitation falls from the clouds as liquid water.
warm at ground
level so...
precipitation is
in melted, liquid
form.
During a rain storm, the
temperature is warm in the
clouds and…
WARM Clouds
Warm surface
17. 17
RAIN
1. Rain - liquid deposits falling from the atmosphere
to the surface
- with a diameter > 0.5 mm
- < 0.5 mm: drizzle
- max. size: about 5 - 7 mm
(too large to remain suspended)
- beyond this size, inter-molecular cohesive
forces become to weak to be held in the
mass of water together as a single drop
18. 18
Snow
Snow occurs when precipitation falls from the clouds as cold, flaky solids.
During a snow storm, the temperature in the
clouds is very cold which freezes the rain into
ice crystals and…
It is also Cold at ground level so…
precipitation is frozen solid in the
clouds and stays frozen by the cold
surface.
Freezing cold clouds
Freezing COLD surface
19. 19
Snow
2. Freezing rain
- when falling liquid water droplets reaches a surface
with a temperature below freezing point
- so, the rain droplets quickly turn into ice
- another * condition: where the rain develops, the
temperature of rain develops must be above
freezing
e.g. within a temperature
inversion
20. 20
Sleet
Sleet occurs when precipitation falls from the clouds to the ground as half
water/half ice.
During a sleet storm, the temperature
of the clouds is warm, so the
precipitation begins to fall as… Warm Clouds
liquid rain.
But, the air around the surface is very cold,
so it begins to freeze the liquid into a slushy
solid. Freezing Cold surface
This slushy solid, which is half frozen, falls
to the ground as sleet.
21. 21
Sleet
• 3. Sleet / ice pellets
- transparent spheres of frozen water
- with a diameter > 5 mm
- develop first as raindrops in relatively warm
atmosphere (Temp: > freezing),
- then raindrops descend into a colder layer of the
atmosphere (Temp:<0oC)
- causing the freezing into ice pellets while reaching
the ground surface
- like freezing rain, an air temperature inversion is
required
22. 22
Because the surface temperature is
very cold during a sleet storm and
everything usually gets covered in ice.
Sleet storms are sometimes called ice storms.
23. 23
HAIL
Hail is precipitation that falls from the clouds to the surface as
balls of ice.
Freezing Cold Clouds
A hail storm begins with
warm surface
temperatures. Very
strong, warm wind
currents push upward
toward the cold clouds.
Precipitation
in the form of
ice begins to
fall from the
clouds.
But it gets
pushed back up
by the strong
wind back into
the clouds
where it joins
with more ice
and grows…
and grows,
and grows
and grows,
until…
The hail stones become so
heavy, the wind can’t hold
them up in the clouds and they
fall to the warm surface.
24. 24
A typical hailstone growth path through a thunderstorm cloud.
Hailstones add most of their mass during updrafts.
HAIL
25. 25
If the upward wind currents are
normal, hail stones will usually be as
big as marbles.
But if the wind currents are very
strong (over 100 miles per hour),
the hail stones can stay up in the
cold clouds for a long time and
grow very large.
These large hailstones cause lots of
damage to cars, homes, crops and
people.
26. 26
TYPES OF RAINFALL
Three types based on the process by
which clouds are formed.
1. Convectional Rainfall
2. Orographic Rainfall
3. Cyclonic or Frontal Rainfall
27. 27
Surface air heated up and rises up.
Cools down in higher altitude.
Fall down as rain.
Accompanies with thunder and lightning.
Resultant clouds are cumulonimbus type.
28. 28
Water vapour
Condenses to form
clouds
Air cools down
Further cooling
leads to heavy
precipitation
Warm air rises
Ground heats up the air
Sun’s rays heat up
the ground
CONVECTIONALRAINFALL
29. 29
CONVECTIONAL RAINFALL
• Rainfall is of short duration and heavy
showers.
• Afternoon rainfall in the equatorial
regions.
• Occurs in early summer in the temperate
regions.
30. 30
2.OROGRAPHIC RAINFALL
• The word orography derived from a
Greek word oros which means a
mountain.
• Found on the windward sides of
mountain ranges lying across the path of
the prevailing terrestrial winds.
• The leeward sides of the mountains is
the rain shadow region.
32. 32
OROGRAPHIC RAINFALL
• Saturated air from sea.
• Hits the mountains.
• Air cools in high altitude.
• Falls as rain in the mountain slope.
33. 33
Mountains forces the air to rise
Water vapour
Condenses to form
clouds
Evaporation of
water from the
ocean
Onshore
moisture laden
winds
Air cools
down
Further cooling
leads to
precipitation
FORMATION OF OROGRAPHIC RAINFALL
Occurs in the mountains
34. 34
OROGRAPHIC RAINFALL
• Rainfall that occurs on the Western
Ghats, southern slopes of Himalayas
and the Great Indian Plains during the
rainy season are orographic type.
35. 35
3.CYCLONIC or frontal RAINFALL
• Occurs along the frontal zones of
convergence.
• Meeting of hot and cold air
• Cold air push up the hot air
• As altitude increase the hot air cool
downs
• Condensation happens
• Rain occurs.
36. 36
Water vapour
Condenses to form
clouds
Warm moisture laden air from
the south meets cold air from
the north and forms the
Warm Front
Warm air rises
Further cooling leads to
precipitation along the
Warm Front
Air cools down
FRONTAL OR DEPRESSION RAINFALL
Cold airWarm air
38. 38
RAINFALL MEASURMENT:
• Rainfall is the main source of water used for
various purpose.
• Instrument used to collect and measure the precipitation is
called rain gauge.
• Rainfall at a place can be measured by a rain
guage, usually in cm.
• Rain guage is a cylindrical vessel assembly
kept in open to collect rain.
39. 39
• TYPES OF RAINGUAGE
TYPES OF RAINGUAGE
NON-RECORDING RAINGUAGE SELF RECORDING(AUTOMATIC)
SYMON’S GUAGE
STANDARD NON RECORDING
•TIPPING BUCKET
•WEIGHING TYPE
•FLOAT TYPE
40. 40
1. Nonrecording Gauges:
• The nonrecording gauge used in India is Symons gauge.
• Consists of a circular collecting area of 12.7 cm diameter
connected to the funnel and the rim of the collector is set in
a horizontal plane at a height of 30.5 cm above the ground
level.
41. 41
• The funnel discharges the rainfall catch into a receiving
vessel which is housed in a metallic container.
• The water in the receiving vessel is measured by a
graduated measuring glass with an accuracy of 0.1 mm.
• The rainfall is measured at 8:30 a.m. and is recorded as
the rainfall of that day.
• The collecting bottle cannot hold more than 10 cm of
rain and thus in case of heavy rainfall frequent readings
must be taken.
• However last reading must be taken at 8:30 a.m. and the
sum of previous readings in the past 24 hours is the
rainfall of that day.
42. 42
(a) Tipping-Bucket type:
• This is a 30.5 cm size raingauge used by US Weather
Bureau.
• The catch from the funnel falls onto one of a pair of
small buckets.
• These buckets are so balanced that when .25 mm of
rainfall collects in one bucket it tips and brings the
other bucket in position and the water is collected in
storage can.
• The water in storage can is measured regularly to give
total rainfall.
SELF RECORDING(AUTOMATIC)
44. 44
(b) Weighing-Bucket type
• The weighing bucket rainguage essentially consisits of a
receiver bucket supported by a spring or lever balance
or any other weighing mechanism. The movement of
bucket due to its on the clock driven recording drum.
• The rainguage produces a graph of cumulative rainfall
versus time.
SELF RECORDING(AUTOMATIC)
46. 46
(c) Float type:
• In this type of rainguage a funnel is provided at one end of
the rectangular container and a rotating recording drum is
provided at the other end.
• The working of a float type rainguage is similar to the
weighing bucket type guage.
• A funnel receives the rain water which is collected In a
rectangular container. A float is provided at the bottom of
container the float is raised as the water level rises in the
container its movement is being recorded by a pen moving
on the graph paper wrapped on the recording clock driven
drum.
• It consist of syphon which starts functioning when flot rises
at some definite height and the container goes on emptying
gradually.
SELF RECORDING(AUTOMATIC)
47. 47
The graphic rain gauge
1-receiver
2-floater
3-siphon
4-recording needle
5-drum with diagram
6-clock mechanism
2. Recording gauge / graphic raingauge
The rainguages that automatically record the intensity of
rainfall over a period of time in the form of pen trace or a
clock driven chart.
48. 48
Advantages of Recording type Rain gauges
A man has not to go the gauge to measure the rain fall
daily
Total amount, Time of onset, Intensity of rainfall can be
obtained in this type of gauge.
They are very useful in remote areas.
Manual errors can be eliminated.
Can be use for long time .
49. 49
Disadvantages of Recording type Rain gauges
It is costly.
Possibility of error due to Mechanical or electrical
disturbances.
Educated persons has to be kept to make readings.
50. 50
Points tobe kept in mind while selecting site for Raingauge station
•Open Land
•Leveled surface
•Sites protected from wind
•Unobstructed places
•Accessibility
•Protection of Rainguage station
51. 51
Methods of calculating average rainfall:
Arithmetic Average Method
Thiessen polygon Method
Isohyetal Method
52. 52
Methods of calculating average rainfall:
Arithmetic Average Method:
This is the simplest method of computing the average rainfall over a
basin. As the name suggests, the result is obtained by the division of the
sum of rain depths recorded at different rain gauge stations of the basin
by the number of the stations. If the rain gauges are uniformly
distributed over the area and the rainfall varies in a very regular manner,
the results obtained by this method will be quite satisfactory and will not
differ much than those obtained by other methods. This method can be
used for the storm rainfall, monthly or annual rainfall average
computations.
53. 53
Methods of calculating average rainfall:
Example: During a storm the rainfall observations in a
selected basin were found as follows: Table: Computation of
average precipitation over a basin using Arithmetic mean
method
54. 54
Methods of calculating average rainfall:
Thiessen Polygon Method
This is the weighted mean method. The rainfall is never uniform over the
entire area of the basin or catchment, but varies in intensity and duration
from place to place. Thus the rainfall recorded by each rain gauge station
should be weighted according to the area, it represents. This method is
more suitable under the following conditions:
- For areas of moderate size.
- When rainfall stations are few compared to the size of
the basin.
- In moderate rugged areas.
For the construction of the polygon, the following procedure is to be
followed:
59. 59
Methods of calculating average rainfall:
isoyetal Method:
An isohyetal is a line joining places where the rainfall
amounts are equal
on a rainfall map of a basin. An isohyetal map showing
contours of equal
rainfall is more accurate picture of the rainfall over the basin.
This
method is more suited under the following conditions:
60. 60
Methods of calculating average rainfall:
- For hilly and rugged areas.
- For large areas over 5000 km2.
- For areas where the network of rainfall stations within
the storm area is sufficiently dense, isohyetal method
gives more accurate distribution of rainfall.
For explaining of drawing an isohyetal map for a basin, the
following
procedure is usually applied:
66. 66
Methods of calculating average rainfall:
Comparison Between the Three Methods:
Arithmetic mean method:
1- This is the simplest and easiest method to compute
average rainfall.
2- In this method every station has equal weight regardless
its location.
3- If the recording stations and rainfall is uniformly
distributed over the entire catchment, then this method is
equally accurate.
67. 67
Methods of calculating average rainfall:
Comparison Between the Three Methods:
Thiessen method:
1-This method is also mechanical
2-In this method the rainfall stations located at a short
distance
beyond the boundary of drainage are also used to
determine the
mean rainfall of the basin, but their influence diminishes as
the
distance from the boundary increases.
3-It is commonly used for flat and low rugged areas.
68. 68
Methods of calculating average rainfall:
Comparison Between the Three Methods:
Isohyetal method:
1- It is the best method for rugged areas and hilly regions.
2- It is the most accurate method if the contours are drawn
correctly. However to obtain the best results good
judgment in drawing the isohyets and in assigning the
proper mean rainfall values to the area between them is
required.
3- Other points are as for Thiessen method.