Rainfall Losses - Revision history

Mpollei@gfnet.com at 04:41, 21 July 2023

2023-07-21T04:41:54Z

← Older revision		Revision as of 04:41, 21 July 2023
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	==Best Practices Resources==		==Best Practices Resources==
	{{Document Icon}} [[National Engineering Handbook: Chapter 7 - Hydrologic Soil Groups \| National Engineering Handbook: Chapter 7 - Hydrologic Soil Groups, NRCS~~, 2009~~]]		{{Document Icon}} [[National Engineering Handbook: Chapter 7 - Hydrologic Soil Groups \| National Engineering Handbook: Chapter 7 - Hydrologic Soil Groups, NRCS]]
	{{Document Icon}} [[National Engineering Handbook: Chapter 9 - Hydrologic Soil-Cover Complexes \| National Engineering Handbook: Chapter 9 - Hydrologic Soil-Cover Complexes, NRCS~~, 2004~~]]		{{Document Icon}} [[National Engineering Handbook: Chapter 9 - Hydrologic Soil-Cover Complexes \| National Engineering Handbook: Chapter 9 - Hydrologic Soil-Cover Complexes, NRCS]]
	{{Document Icon}} [[National Engineering Handbook: Chapter 10 - Estimation of Direct Runoff from Storm Rainfall \| National Engineering Handbook: Chapter 10 - Estimation of Direct Runoff from Storm Rainfall, NRCS~~, 2004~~]]		{{Document Icon}} [[National Engineering Handbook: Chapter 10 - Estimation of Direct Runoff from Storm Rainfall \| National Engineering Handbook: Chapter 10 - Estimation of Direct Runoff from Storm Rainfall, NRCS]]
	{{Document Icon}} [[Flood Hydrology Manual \| Flood Hydrology Manual, USBR~~, 1989~~]]		{{Document Icon}} [[Flood Hydrology Manual \| Flood Hydrology Manual, USBR]]

	<!-- In the location of an in text citation, simply enclose the citation as follows: <ref> citation </ref>. Citations will automatically populate. Learn more at https://www.mediawiki.org/wiki/Help:Cite. -->		<!-- In the location of an in text citation, simply enclose the citation as follows: <ref> citation </ref>. Citations will automatically populate. Learn more at https://www.mediawiki.org/wiki/Help:Cite. -->

Rmanwaring at 20:11, 19 December 2022

2022-12-19T20:11:55Z

← Older revision		Revision as of 20:11, 19 December 2022
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	==Best Practices Resources==		==Best Practices Resources==
	~~{{Document Icon}} [[Flood Hydrology Manual \| Flood Hydrology Manual (Bureau of Reclamation)]]~~		{{Document Icon}} [[National Engineering Handbook: Chapter 7 - Hydrologic Soil Groups \| National Engineering Handbook: Chapter 7 - Hydrologic Soil Groups, NRCS, 2009]]
	{{Document Icon}} [[National Engineering Handbook: Chapter 7 - Hydrologic Soil Groups \| National Engineering Handbook: Chapter 7 - Hydrologic Soil Groups ~~(Natural Resources Conservation Service)~~]]		{{Document Icon}} [[National Engineering Handbook: Chapter 9 - Hydrologic Soil-Cover Complexes \| National Engineering Handbook: Chapter 9 - Hydrologic Soil-Cover Complexes, NRCS, 2004]]
	{{Document Icon}} [[National Engineering Handbook: Chapter 9 - Hydrologic Soil-Cover Complexes \| National Engineering Handbook: Chapter 9 - Hydrologic Soil-Cover Complexes ~~(Natural Resources Conservation Service)~~]]		{{Document Icon}} [[National Engineering Handbook: Chapter 10 - Estimation of Direct Runoff from Storm Rainfall \| National Engineering Handbook: Chapter 10 - Estimation of Direct Runoff from Storm Rainfall, NRCS, 2004]]
	{{Document Icon}} [[National Engineering Handbook: Chapter 10 - Estimation of Direct Runoff from Storm Rainfall \| National Engineering Handbook: Chapter 10 - Estimation of Direct Runoff from Storm Rainfall ~~(Natural Resources Conservation Service)~~]]		{{Document Icon}} [[Flood Hydrology Manual \| Flood Hydrology Manual, USBR, 1989]]

	<!-- In the location of an in text citation, simply enclose the citation as follows: <ref> citation </ref>. Citations will automatically populate. Learn more at https://www.mediawiki.org/wiki/Help:Cite. -->		<!-- In the location of an in text citation, simply enclose the citation as follows: <ref> citation </ref>. Citations will automatically populate. Learn more at https://www.mediawiki.org/wiki/Help:Cite. -->

Grichards at 03:33, 13 December 2022

2022-12-13T03:33:39Z

← Older revision		Revision as of 03:33, 13 December 2022
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	#"Retention in surface depressions that act as miniature [[reservoirs]] that do not release their waters until their storage capacity is exceeded, and then only in relation to a stage versus discharge relationship comparable to an uncontrolled spillway on a reservoir.		#"Retention in surface depressions that act as miniature [[reservoirs]] that do not release their waters until their storage capacity is exceeded, and then only in relation to a stage versus discharge relationship comparable to an uncontrolled spillway on a reservoir.
	#"Infiltration into the receiving soil, rock, or combination thereof." <ref name="Reclamation">[[Flood Hydrology Manual\| Flood Hydrology Manual, Bureau of Reclamation, 1989]]</ref>		#"Infiltration into the receiving soil, rock, or combination thereof." <ref name="Reclamation">[[Flood Hydrology Manual\| Flood Hydrology Manual, Bureau of Reclamation, 1989]]</ref>


	"Any of the constituents of the Earth’s mantle have a capability to absorb water, whether it is a concrete airport parking and loading area or the most sandy of [[soils]] comprising some areas of the arid West. The first three of the above loss processes are usually low when compared with infiltration when rainfall intensities are sufficient to produce severe flood events such as the PMF. Under such conditions, the first three are often grouped with part of the infiltration loss and termed “initial losses,” and assumed to have been satisfied by antecedent rainfall occurring prior to the onset of the PMS."<ref name="Reclamation"/>		"Any of the constituents of the Earth’s mantle have a capability to absorb water, whether it is a concrete airport parking and loading area or the most sandy of [[soils]] comprising some areas of the arid West. The first three of the above loss processes are usually low when compared with infiltration when rainfall intensities are sufficient to produce severe flood events such as the PMF. Under such conditions, the first three are often grouped with part of the infiltration loss and termed “initial losses,” and assumed to have been satisfied by antecedent rainfall occurring prior to the onset of the PMS."<ref name="Reclamation"/>

Grichards at 03:33, 13 December 2022

2022-12-13T03:33:15Z

← Older revision		Revision as of 03:33, 13 December 2022
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	[[Category:Rainfall Runoff Modeling]]		[[Category:Rainfall Runoff Modeling]]
	----		----
	~~<!-- Introductory paragraph~~ or ~~topic page summary -->~~		“The flood hydrologist is primarily concerned with:
	~~“Evaporation data~~ is ~~usually required for~~ reservoir ~~studies~~, ~~particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan evaporation~~ or ~~computing potential evaporation”~~.<ref name="~~EM 1110-2-1420~~">[[~~Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420)~~ \| ~~EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs~~, ~~USACE~~, ~~1997~~]]</ref>		#"Interception by vegetation and subsequent evaporation or retardation when reaching the ground surface.
			#"Evaporation from ground surface during prolonged rainfall events or when accumulated in frozen form from snowfall, which is generally termed “sublimation.”
			#"Retention in surface depressions that act as miniature [[reservoirs]] that do not release their waters until their storage capacity is exceeded, and then only in relation to a stage versus discharge relationship comparable to an uncontrolled spillway on a reservoir.
			#"Infiltration into the receiving soil, rock, or combination thereof." <ref name="Reclamation">[[Flood Hydrology Manual\| Flood Hydrology Manual, Bureau of Reclamation, 1989]]</ref>

	~~“Evapotranspiration (ET) is difficult~~ to ~~estimate because~~ it is a ~~complex process. It is determined by the atmospheric demand for water vapor (potential ET)~~ and the ~~availability~~ of ~~water to be evaporated~~. ~~ET is a sum~~ of ~~pure evaporation from free water surfaces,~~ such as ~~wet vegetation, puddles~~, and ~~lakes~~, and the ~~transfer~~ of ~~soil moisture through plants and out their leaves (transpiration). The former process depends only on~~ the ~~atmospheric conditions (temperature, humidity, wind), whereas the latter also depends on plant characteristics (stomatal resistance) and on soil moisture availability”~~.<ref name="~~NEH210-630-20~~"~~>[[National Engineering Handbook Hydrology: Chapter 20 Watershed Yield \| National Engineering Handbook Hydrology: Chapter 20 Watershed Yield, NRCS, 2009]]<~~/~~ref~~>		"Any of the constituents of the Earth’s mantle have a capability to absorb water, whether it is a concrete airport parking and loading area or the most sandy of [[soils]] comprising some areas of the arid West. The first three of the above loss processes are usually low when compared with infiltration when rainfall intensities are sufficient to produce severe flood events such as the PMF. Under such conditions, the first three are often grouped with part of the infiltration loss and termed “initial losses,” and assumed to have been satisfied by antecedent rainfall occurring prior to the onset of the PMS."<ref name="Reclamation"/>

	~~“Many models are available for estimating potential evapotranspiration from meteorological data (Jensen~~, ~~Burman~~, and ~~Allen 1990; ASCE 1996). They vary in their assumptions~~, the ~~processes described~~, the ~~input data required~~, and the ~~temporal scale for which they are appropriate~~. ~~Potential ET can also be estimated from pan evaporation data if suitable pan coefficients are available” <ref name="NEH210-630-20" />~~		"To illustrate the phenomena that occurs in the soil when water is applied in the form of rain, consider a condition at the onset of a rainstorm where the soil is comparatively dry as a result of no [[precipitation]] having recently occurred. Initially, part of the precipitation is intercepted by vegetation and, after the vegetation has reached its capacity to retain water by surface tension, additional precipitation simply runs off the leaves, stems, etc., and falls to the ground. Also, part of the rainfall falls directly on the ground surface and enters the soil. In nature, some of this precipitation evaporates back into the atmosphere; however, in the hydrologic analysis of floods, interception and evaporation losses are so small compared to the magnitude of the precipitation that they are neglected."<ref name="Reclamation"/>

	~~“Even if potential ET is adequately estimated~~, the ~~actual ET is less than or equal to this amount~~ and ~~depends primarily on~~ soil ~~moisture availability~~. ~~Because~~ of this ~~interplay between~~ the ~~atmospheric demand and the soil moisture~~, ~~determining~~ the ~~actual ET is problematic without a detailed~~ hydrologic ~~model operated at a short time step (i.e.~~, ~~a day or less). If adequate assumptions can be made, however, reasonable estimates~~ of ~~actual ET as a fraction of potential ET~~ are ~~possible”~~.<ref name="~~NEH210-630-20~~" />

	==Best Practices Resources==		==Best Practices Resources==

Grichards at 02:49, 13 December 2022

2022-12-13T02:49:55Z

← Older revision		Revision as of 02:49, 13 December 2022
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	<!-- Delete any sections that are not necessary to your topic. Add pictures/sections as needed -->		<!-- Delete any sections that are not necessary to your topic. Add pictures/sections as needed -->
	__NOTOC__		__NOTOC__
			[[Category:Rainfall Runoff Modeling]]
	----		----

	<!-- Introductory paragraph or topic page summary -->		<!-- Introductory paragraph or topic page summary -->
	“Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan evaporation or computing potential evaporation”.<ref name="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs, USACE, 1997]]</ref>		“Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan evaporation or computing potential evaporation”.<ref name="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs, USACE, 1997]]</ref>

Rmanwaring at 19:46, 21 October 2022

2022-10-21T19:46:23Z

← Older revision		Revision as of 19:46, 21 October 2022
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	“Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan evaporation or computing potential evaporation”.<ref name="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs, USACE, 1997]]</ref>		“Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan evaporation or computing potential evaporation”.<ref name="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs, USACE, 1997]]</ref>

	“Evapotranspiration (ET) is difficult to estimate because it is a complex process. It is determined by the atmospheric demand for water vapor (potential ET) and the availability of water to be evaporated. ET is a sum of pure evaporation from free water surfaces, such as wet vegetation, puddles, and lakes, and the transfer of soil moisture through plants and out their leaves (transpiration). The former process depends only on the atmospheric conditions (temperature, humidity, wind), whereas the latter also depends on plant characteristics (stomatal resistance) and on soil moisture availability”.<ref name="NEH210-630-20">[[National Engineering Handbook ~~210 Part 630~~ Hydrology: Chapter 20 Watershed Yield \| National Engineering Handbook ~~210 Part 630~~ Hydrology: Chapter 20 Watershed Yield, NRCS, 2009]]</ref>		“Evapotranspiration (ET) is difficult to estimate because it is a complex process. It is determined by the atmospheric demand for water vapor (potential ET) and the availability of water to be evaporated. ET is a sum of pure evaporation from free water surfaces, such as wet vegetation, puddles, and lakes, and the transfer of soil moisture through plants and out their leaves (transpiration). The former process depends only on the atmospheric conditions (temperature, humidity, wind), whereas the latter also depends on plant characteristics (stomatal resistance) and on soil moisture availability”.<ref name="NEH210-630-20">[[National Engineering Handbook Hydrology: Chapter 20 Watershed Yield \| National Engineering Handbook Hydrology: Chapter 20 Watershed Yield, NRCS, 2009]]</ref>

	“Many models are available for estimating potential evapotranspiration from meteorological data (Jensen, Burman, and Allen 1990; ASCE 1996). They vary in their assumptions, the processes described, the input data required, and the temporal scale for which they are appropriate. Potential ET can also be estimated from pan evaporation data if suitable pan coefficients are available” <ref name="NEH210-630-20" />		“Many models are available for estimating potential evapotranspiration from meteorological data (Jensen, Burman, and Allen 1990; ASCE 1996). They vary in their assumptions, the processes described, the input data required, and the temporal scale for which they are appropriate. Potential ET can also be estimated from pan evaporation data if suitable pan coefficients are available” <ref name="NEH210-630-20" />
Line 13:		Line 13:

	==Best Practices Resources==		==Best Practices Resources==
	{{Document Icon}} [[Flood Hydrology Manual\|Flood Hydrology Manual (Bureau of Reclamation)]]		{{Document Icon}} [[Flood Hydrology Manual \| Flood Hydrology Manual (Bureau of Reclamation)]]
	{{Document Icon}} [[~~Hydrology~~ National Engineering Handbook: Chapter 7- Hydrologic Soil Groups\|National Engineering Handbook: Chapter 7- Hydrologic Soil Groups (Natural Resources Conservation Service)]]		{{Document Icon}} [[National Engineering Handbook: Chapter 7 - Hydrologic Soil Groups \| National Engineering Handbook: Chapter 7 - Hydrologic Soil Groups (Natural Resources Conservation Service)]]
	{{Document Icon}} [[~~Hydrology~~ National Engineering Handbook: Chapter 9- Hydrologic Soil-Cover Complexes\|National Engineering Handbook: Chapter 9- Hydrologic Soil-Cover Complexes (Natural Resources Conservation Service)]]		{{Document Icon}} [[National Engineering Handbook: Chapter 9 - Hydrologic Soil-Cover Complexes \| National Engineering Handbook: Chapter 9 - Hydrologic Soil-Cover Complexes (Natural Resources Conservation Service)]]
	{{Document Icon}} [[~~Hydrology~~ National Engineering Handbook: Chapter 10- Estimation of Direct Runoff from Storm Rainfall\|National Engineering Handbook: Chapter 10- Estimation of Direct Runoff from Storm Rainfall (Natural Resources Conservation Service)]]		{{Document Icon}} [[National Engineering Handbook: Chapter 10 - Estimation of Direct Runoff from Storm Rainfall \| National Engineering Handbook: Chapter 10 - Estimation of Direct Runoff from Storm Rainfall (Natural Resources Conservation Service)]]

	<!-- In the location of an in text citation, simply enclose the citation as follows: <ref> citation </ref>. Citations will automatically populate. Learn more at https://www.mediawiki.org/wiki/Help:Cite. -->		<!-- In the location of an in text citation, simply enclose the citation as follows: <ref> citation </ref>. Citations will automatically populate. Learn more at https://www.mediawiki.org/wiki/Help:Cite. -->

Grichards at 01:02, 17 September 2022

2022-09-17T01:02:08Z

← Older revision		Revision as of 01:02, 17 September 2022
Line 8:		Line 8:
	“Evapotranspiration (ET) is difficult to estimate because it is a complex process. It is determined by the atmospheric demand for water vapor (potential ET) and the availability of water to be evaporated. ET is a sum of pure evaporation from free water surfaces, such as wet vegetation, puddles, and lakes, and the transfer of soil moisture through plants and out their leaves (transpiration). The former process depends only on the atmospheric conditions (temperature, humidity, wind), whereas the latter also depends on plant characteristics (stomatal resistance) and on soil moisture availability”.<ref name="NEH210-630-20">[[National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield \| National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield, NRCS, 2009]]</ref>		“Evapotranspiration (ET) is difficult to estimate because it is a complex process. It is determined by the atmospheric demand for water vapor (potential ET) and the availability of water to be evaporated. ET is a sum of pure evaporation from free water surfaces, such as wet vegetation, puddles, and lakes, and the transfer of soil moisture through plants and out their leaves (transpiration). The former process depends only on the atmospheric conditions (temperature, humidity, wind), whereas the latter also depends on plant characteristics (stomatal resistance) and on soil moisture availability”.<ref name="NEH210-630-20">[[National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield \| National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield, NRCS, 2009]]</ref>

	“Many models are available for estimating potential evapotranspiration from meteorological data (Jensen, Burman, and Allen 1990; ASCE 1996). They vary in their assumptions, the processes described, the input data required, and the temporal scale for which they are appropriate. Potential ET can also be estimated from pan evaporation data if suitable pan coefficients are available” ~~(National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield, NRCS, 2009).~~<ref name="NEH210-630-20" />		“Many models are available for estimating potential evapotranspiration from meteorological data (Jensen, Burman, and Allen 1990; ASCE 1996). They vary in their assumptions, the processes described, the input data required, and the temporal scale for which they are appropriate. Potential ET can also be estimated from pan evaporation data if suitable pan coefficients are available” <ref name="NEH210-630-20" />

	“Even if potential ET is adequately estimated, the actual ET is less than or equal to this amount and depends primarily on soil moisture availability. Because of this interplay between the atmospheric demand and the soil moisture, determining the actual ET is problematic without a detailed hydrologic model operated at a short time step (i.e., a day or less). If adequate assumptions can be made, however, reasonable estimates of actual ET as a fraction of potential ET are possible”.<ref name="NEH210-630-20" />		“Even if potential ET is adequately estimated, the actual ET is less than or equal to this amount and depends primarily on soil moisture availability. Because of this interplay between the atmospheric demand and the soil moisture, determining the actual ET is problematic without a detailed hydrologic model operated at a short time step (i.e., a day or less). If adequate assumptions can be made, however, reasonable estimates of actual ET as a fraction of potential ET are possible”.<ref name="NEH210-630-20" />

Grichards at 01:01, 17 September 2022

2022-09-17T01:01:12Z

← Older revision		Revision as of 01:01, 17 September 2022
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	__NOTOC__		__NOTOC__
	----		----
	~~{{Picture~~
	~~<!-- Add image file name (ex.image.jpg) -->~~
	~~\|image=~~
	~~<!--Add link if applicable -->~~
	~~\|link=~~
	~~<!-- Add picture caption -->~~
	~~\|caption=~~
	}}

	<!-- Introductory paragraph or topic page summary -->		<!-- Introductory paragraph or topic page summary -->

Grichards at 01:00, 17 September 2022

2022-09-17T01:00:59Z

← Older revision		Revision as of 01:00, 17 September 2022
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	<!-- Introductory paragraph or topic page summary -->		<!-- Introductory paragraph or topic page summary -->
	“Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan evaporation or computing potential evaporation”.<ref name="EM 1110-2-1420" />		“Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan evaporation or computing potential evaporation”.<ref name="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs, USACE, 1997]]</ref>

	“Evapotranspiration (ET) is difficult to estimate because it is a complex process. It is determined by the atmospheric demand for water vapor (potential ET) and the availability of water to be evaporated. ET is a sum of pure evaporation from free water surfaces, such as wet vegetation, puddles, and lakes, and the transfer of soil moisture through plants and out their leaves (transpiration). The former process depends only on the atmospheric conditions (temperature, humidity, wind), whereas the latter also depends on plant characteristics (stomatal resistance) and on soil moisture availability”.<ref name="NEH210-630-20" />		“Evapotranspiration (ET) is difficult to estimate because it is a complex process. It is determined by the atmospheric demand for water vapor (potential ET) and the availability of water to be evaporated. ET is a sum of pure evaporation from free water surfaces, such as wet vegetation, puddles, and lakes, and the transfer of soil moisture through plants and out their leaves (transpiration). The former process depends only on the atmospheric conditions (temperature, humidity, wind), whereas the latter also depends on plant characteristics (stomatal resistance) and on soil moisture availability”.<ref name="NEH210-630-20">[[National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield \| National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield, NRCS, 2009]]</ref>

	“Many models are available for estimating potential evapotranspiration from meteorological data (Jensen, Burman, and Allen 1990; ASCE 1996). They vary in their assumptions, the processes described, the input data required, and the temporal scale for which they are appropriate. Potential ET can also be estimated from pan evaporation data if suitable pan coefficients are available” (National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield, NRCS, 2009).<ref name="NEH210-630-20" />		“Many models are available for estimating potential evapotranspiration from meteorological data (Jensen, Burman, and Allen 1990; ASCE 1996). They vary in their assumptions, the processes described, the input data required, and the temporal scale for which they are appropriate. Potential ET can also be estimated from pan evaporation data if suitable pan coefficients are available” (National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield, NRCS, 2009).<ref name="NEH210-630-20" />

Grichards: Created page with " NOTOC ---- {{Picture |image= |link= |caption= }} “Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan eva..."

2022-09-17T01:00:13Z

Created page with " __NOTOC__ ---- {{Picture  |image=  |link=  |caption= }}  “Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan eva..."

New page

__NOTOC__
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“Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan evaporation or computing potential evaporation”.<ref name="EM 1110-2-1420" />

“Evapotranspiration (ET) is difficult to estimate because it is a complex process. It is determined by the atmospheric demand for water vapor (potential ET) and the availability of water to be evaporated. ET is a sum of pure evaporation from free water surfaces, such as wet vegetation, puddles, and lakes, and the transfer of soil moisture through plants and out their leaves (transpiration). The former process depends only on the atmospheric conditions (temperature, humidity, wind), whereas the latter also depends on plant characteristics (stomatal resistance) and on soil moisture availability”.<ref name="NEH210-630-20" />

“Many models are available for estimating potential evapotranspiration from meteorological data (Jensen, Burman, and Allen 1990; ASCE 1996). They vary in their assumptions, the processes described, the input data required, and the temporal scale for which they are appropriate. Potential ET can also be estimated from pan evaporation data if suitable pan coefficients are available” (National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield, NRCS, 2009).<ref name="NEH210-630-20" />

“Even if potential ET is adequately estimated, the actual ET is less than or equal to this amount and depends primarily on soil moisture availability. Because of this interplay between the atmospheric demand and the soil moisture, determining the actual ET is problematic without a detailed hydrologic model operated at a short time step (i.e., a day or less). If adequate assumptions can be made, however, reasonable estimates of actual ET as a fraction of potential ET are possible”.<ref name="NEH210-630-20" />

==Best Practices Resources==
{{Document Icon}} [[Flood Hydrology Manual|Flood Hydrology Manual (Bureau of Reclamation)]]
{{Document Icon}} [[Hydrology National Engineering Handbook: Chapter 7- Hydrologic Soil Groups|National Engineering Handbook: Chapter 7- Hydrologic Soil Groups (Natural Resources Conservation Service)]]
{{Document Icon}} [[Hydrology National Engineering Handbook: Chapter 9- Hydrologic Soil-Cover Complexes|National Engineering Handbook: Chapter 9- Hydrologic Soil-Cover Complexes (Natural Resources Conservation Service)]]
{{Document Icon}} [[Hydrology National Engineering Handbook: Chapter 10- Estimation of Direct Runoff from Storm Rainfall|National Engineering Handbook: Chapter 10- Estimation of Direct Runoff from Storm Rainfall (Natural Resources Conservation Service)]]


{{Citations}}


{{revhistinf}}

Rainfall Losses - Revision history

Mpollei@gfnet.com at 04:41, 21 July 2023

Rmanwaring at 20:11, 19 December 2022

Grichards at 03:33, 13 December 2022

Grichards at 03:33, 13 December 2022

Grichards at 02:49, 13 December 2022

Rmanwaring at 19:46, 21 October 2022

Grichards at 01:02, 17 September 2022

Grichards at 01:01, 17 September 2022

Grichards at 01:00, 17 September 2022

Grichards: Created page with " __NOTOC__ ---- {{Picture |image= |link= |caption= }} “Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan eva..."

Grichards: Created page with " NOTOC ---- {{Picture |image= |link= |caption= }} “Evaporation data is usually required for reservoir studies, particularly for low-flow analysis. Reservoir evaporation is typically estimated by measuring pan eva..."