OR/14/011 Component summary - Revision history

Ajhil: /* Debris flow component */

2022-04-22T10:59:32Z

Debris flow component

← Older revision		Revision as of 11:59, 22 April 2022
Line 112:		Line 112:
	The failure angle decreases with increasing moisture content due to loss of shear strength. Potential angle of failure can be lower than 20° for soils with lower internal friction angles which could result in the prediction of widespread slope failure if cohesion is not taken into consideration. Currently the landslide trigger condition within SCIDDICA assumes that the soil is permanently saturated so that for a prescribed internal friction angle, the failure angle would be given by the right hand edge of Figure 2. Equations 2.21 and 2.23 describe the link between stability and the hydrological conditions modelled within the CLiDE platform.		The failure angle decreases with increasing moisture content due to loss of shear strength. Potential angle of failure can be lower than 20° for soils with lower internal friction angles which could result in the prediction of widespread slope failure if cohesion is not taken into consideration. Currently the landslide trigger condition within SCIDDICA assumes that the soil is permanently saturated so that for a prescribed internal friction angle, the failure angle would be given by the right hand edge of Figure 2. Equations 2.21 and 2.23 describe the link between stability and the hydrological conditions modelled within the CLiDE platform.

	[[Image:OR14011fig2.jpg\|thumb\|center\|~~350px~~\| '''Figure 2'''    Variation in the failure angle for a shallow landslide as a function of soil moisture and the internal friction angle follow infinite slope stability analysis (see equation 2.23). Cohesion was assumed negligible (C* set to zero). Increased soil moisture causes a reduction in the angle up to which hillslopes might be stable. ]]		[[Image:OR14011fig2.jpg\|thumb\|center\|300px\| '''Figure 2'''    Variation in the failure angle for a shallow landslide as a function of soil moisture and the internal friction angle follow infinite slope stability analysis (see equation 2.23). Cohesion was assumed negligible (C* set to zero). Increased soil moisture causes a reduction in the angle up to which hillslopes might be stable. ]]

	==Climate change component==		==Climate change component==

Ajhil: /* Debris flow component */

2022-04-22T10:59:23Z

Debris flow component

← Older revision		Revision as of 11:59, 22 April 2022
Line 112:		Line 112:
	The failure angle decreases with increasing moisture content due to loss of shear strength. Potential angle of failure can be lower than 20° for soils with lower internal friction angles which could result in the prediction of widespread slope failure if cohesion is not taken into consideration. Currently the landslide trigger condition within SCIDDICA assumes that the soil is permanently saturated so that for a prescribed internal friction angle, the failure angle would be given by the right hand edge of Figure 2. Equations 2.21 and 2.23 describe the link between stability and the hydrological conditions modelled within the CLiDE platform.		The failure angle decreases with increasing moisture content due to loss of shear strength. Potential angle of failure can be lower than 20° for soils with lower internal friction angles which could result in the prediction of widespread slope failure if cohesion is not taken into consideration. Currently the landslide trigger condition within SCIDDICA assumes that the soil is permanently saturated so that for a prescribed internal friction angle, the failure angle would be given by the right hand edge of Figure 2. Equations 2.21 and 2.23 describe the link between stability and the hydrological conditions modelled within the CLiDE platform.

	[[Image:OR14011fig2.jpg\|thumb\|center\|~~500px~~\| '''Figure 2'''    Variation in the failure angle for a shallow landslide as a function of soil moisture and the internal friction angle follow infinite slope stability analysis (see equation 2.23). Cohesion was assumed negligible (C* set to zero). Increased soil moisture causes a reduction in the angle up to which hillslopes might be stable. ]]		[[Image:OR14011fig2.jpg\|thumb\|center\|350px\| '''Figure 2'''    Variation in the failure angle for a shallow landslide as a function of soil moisture and the internal friction angle follow infinite slope stability analysis (see equation 2.23). Cohesion was assumed negligible (C* set to zero). Increased soil moisture causes a reduction in the angle up to which hillslopes might be stable. ]]

	==Climate change component==		==Climate change component==

Ajhil at 10:58, 22 April 2022

2022-04-22T10:58:40Z

Show changes

Ajhil: /* Surface water routing component */

2022-04-22T10:57:38Z

Surface water routing component

← Older revision		Revision as of 11:57, 22 April 2022
Line 26:		Line 26:
	Routing of surface runoff and channel flow is controlled by Lisflood (Van der Knijff et al., 2010<ref name="Van der Knijff 2010">Van der Knijff, J M, Younis, J, and De Roo, A P J. 2010. LISFLOOD: a GIS-based distributed model for river basin scale water balance and flood simulation. Int. J. Geogr. Inf. Sci., 24, 189–212.</ref>), a two-dimensional hydrodynamic flow model. Routing is based on the one dimensional Saint-Venant equations, as modified by Bates et al. (2010)<ref name="Bates 2010">Bates, P D, Horritt, M S, and Fewtrell, T J. 2010. A simple inertial formulation of the shallow water equations for efficient two-dimensional flood inundation modelling. J. Hydrol., 387, 33–45.</ref>, where the derived equation (2.6) takes into account; acceleration, water surface gradient and friction properties and has enhanced stability due to increased friction forcing water flow towards zero (Liang et al., 2006<ref name="Liang 2006">Liang, D, Falconer, R A, and Lin, B. 2006. Improved numerical modelling of estuarine flows. Proceedings of the Institution of Civil Engineers, Maritime Engineering, 159 (1), 25–35</ref>):		Routing of surface runoff and channel flow is controlled by Lisflood (Van der Knijff et al., 2010<ref name="Van der Knijff 2010">Van der Knijff, J M, Younis, J, and De Roo, A P J. 2010. LISFLOOD: a GIS-based distributed model for river basin scale water balance and flood simulation. Int. J. Geogr. Inf. Sci., 24, 189–212.</ref>), a two-dimensional hydrodynamic flow model. Routing is based on the one dimensional Saint-Venant equations, as modified by Bates et al. (2010)<ref name="Bates 2010">Bates, P D, Horritt, M S, and Fewtrell, T J. 2010. A simple inertial formulation of the shallow water equations for efficient two-dimensional flood inundation modelling. J. Hydrol., 387, 33–45.</ref>, where the derived equation (2.6) takes into account; acceleration, water surface gradient and friction properties and has enhanced stability due to increased friction forcing water flow towards zero (Liang et al., 2006<ref name="Liang 2006">Liang, D, Falconer, R A, and Lin, B. 2006. Improved numerical modelling of estuarine flows. Proceedings of the Institution of Civil Engineers, Maritime Engineering, 159 (1), 25–35</ref>):

	[[Image:OR14011equation2.6a.jpg~~\|thumb~~\|center\|~~500px~~\| ]]		[[Image:OR14011equation2.6a.jpg\|center\|600px\| ]]

	If the flow depth ''(h<sub>f</sub>)'', as calculated using the surface partitioning component, is above a defined threshold and stability criteria are met, the flux between cells at the proceeding time-step ''(q<sub>t+dt</sub>)'' depends on the water surface gradient between the adjacent cells ''(S)'', Manning’s coefficient ''(n)'', the time-step length ''(dt)'' and the gravitational constant ''(g)''. For each time-step flow between neighbouring cells is computed and flow depths updated simultaneously at all points within the model domain. A full description of CAESAR-Lisflood is provided by Coulthard et al. (2013).		If the flow depth ''(h<sub>f</sub>)'', as calculated using the surface partitioning component, is above a defined threshold and stability criteria are met, the flux between cells at the proceeding time-step ''(q<sub>t+dt</sub>)'' depends on the water surface gradient between the adjacent cells ''(S)'', Manning’s coefficient ''(n)'', the time-step length ''(dt)'' and the gravitational constant ''(g)''. For each time-step flow between neighbouring cells is computed and flow depths updated simultaneously at all points within the model domain. A full description of CAESAR-Lisflood is provided by Coulthard et al. (2013).

Ajhil: /* Water partitioning component */

2022-04-22T10:57:28Z

Water partitioning component

← Older revision		Revision as of 11:57, 22 April 2022
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	[[Image:OR14011equation2.1a.jpg\|center\|600px\| ]]		[[Image:OR14011equation2.1a.jpg\|center\|600px\| ]]
	<br>		<br>
	[[Image:OR14011equation2.2a.jpg\|~~left~~\|~~150px~~\| ]]		[[Image:OR14011equation2.2a.jpg\|center\|600px\| ]]

	''BFI'' is an average surface to subsurface water partitioning ratio reflecting the permeable nature of the catchment in addition to other catchment characteristics. In general greater runoff and reduced recharge is observed in areas with steeper slopes. Consequently equations 2.1 and 2.2 are modified to allow average (S overbar) and nodal (S) terrain gradient to be factored into the calculation of recharge and runoff:		''BFI'' is an average surface to subsurface water partitioning ratio reflecting the permeable nature of the catchment in addition to other catchment characteristics. In general greater runoff and reduced recharge is observed in areas with steeper slopes. Consequently equations 2.1 and 2.2 are modified to allow average (S overbar) and nodal (S) terrain gradient to be factored into the calculation of recharge and runoff:

	[[Image:OR14011equation2.3a.jpg~~\|thumb~~\|center\|~~500px~~\| ]]		[[Image:OR14011equation2.3a.jpg\|center\|600px\| ]]

	[[Image:OR14011equation2.4a.jpg~~\|thumb~~\|center\|~~500px~~\| ]]		[[Image:OR14011equation2.4a.jpg\|center\|600px\| ]]

	[[Image:OR14011equation2.5a.jpg~~\|thumb~~\|center\|~~500px~~\| ]]		[[Image:OR14011equation2.5a.jpg\|center\|600px\| ]]

	==Surface water routing component==		==Surface water routing component==

Ajhil at 08:59, 22 April 2022

2022-04-22T08:59:54Z

Show changes

Ajhil: /* Water partitioning component */

2022-04-20T09:47:24Z

Water partitioning component

← Older revision		Revision as of 10:47, 20 April 2022
Line 11:		Line 11:
	Within SLiM, rainfall that isn’t evaporated, or doesn’t contribute directly to runoff, can be either intercepted by plants or reach the ground surface and infiltrate into the soil. The latter has the effect of increasing near surface soil storage and reducing the soil moisture deficit ''(SMD)''. Soil water can be extracted by plant roots for transpiration or drawn to the bare soil surface for evaporation. When soil moisture reaches field capacity and is unable to store further additions of water, water drains freely in the saturated soil. At field capacity if there are additional water inputs, lateral runoff (routed by Lisflood) occurs if a gradient exists towards adjacent locations. If the rainfall intensity is greater than the capacity of soil to maintain infiltration, water accumulates on the soil surface and becomes surface runoff. Water not accounted for in soil storage, evapotranspiration or uptake by vegetation is termed ''excess water (E<sub>w</sub>)''. Excess water is divided between runoff (R<sub>o</sub>) and recharge to groundwater (R<sub>e</sub>) based on a baseflow index parameter ''(BFI)''. The BFI may be derived through a calibration process or estimated from data by performing a baseflow separation on a river flow time-series. Surface runoff and recharge to groundwater are calculated using equations 2.1 and 2.2:		Within SLiM, rainfall that isn’t evaporated, or doesn’t contribute directly to runoff, can be either intercepted by plants or reach the ground surface and infiltrate into the soil. The latter has the effect of increasing near surface soil storage and reducing the soil moisture deficit ''(SMD)''. Soil water can be extracted by plant roots for transpiration or drawn to the bare soil surface for evaporation. When soil moisture reaches field capacity and is unable to store further additions of water, water drains freely in the saturated soil. At field capacity if there are additional water inputs, lateral runoff (routed by Lisflood) occurs if a gradient exists towards adjacent locations. If the rainfall intensity is greater than the capacity of soil to maintain infiltration, water accumulates on the soil surface and becomes surface runoff. Water not accounted for in soil storage, evapotranspiration or uptake by vegetation is termed ''excess water (E<sub>w</sub>)''. Excess water is divided between runoff (R<sub>o</sub>) and recharge to groundwater (R<sub>e</sub>) based on a baseflow index parameter ''(BFI)''. The BFI may be derived through a calibration process or estimated from data by performing a baseflow separation on a river flow time-series. Surface runoff and recharge to groundwater are calculated using equations 2.1 and 2.2:

	[[Image:OR14011equation2.1a.jpg\|center\|~~700px~~\| ]]		[[Image:OR14011equation2.1a.jpg\|center\|600px\| ]]
	<br>		<br>
	[[Image:OR14011equation2.2.jpg\|left\|150px\| ]]		[[Image:OR14011equation2.2.jpg\|left\|150px\| ]]

Ajhil: /* Water partitioning component */

2022-04-20T09:47:02Z

Water partitioning component

← Older revision		Revision as of 10:47, 20 April 2022
Line 11:		Line 11:
	Within SLiM, rainfall that isn’t evaporated, or doesn’t contribute directly to runoff, can be either intercepted by plants or reach the ground surface and infiltrate into the soil. The latter has the effect of increasing near surface soil storage and reducing the soil moisture deficit ''(SMD)''. Soil water can be extracted by plant roots for transpiration or drawn to the bare soil surface for evaporation. When soil moisture reaches field capacity and is unable to store further additions of water, water drains freely in the saturated soil. At field capacity if there are additional water inputs, lateral runoff (routed by Lisflood) occurs if a gradient exists towards adjacent locations. If the rainfall intensity is greater than the capacity of soil to maintain infiltration, water accumulates on the soil surface and becomes surface runoff. Water not accounted for in soil storage, evapotranspiration or uptake by vegetation is termed ''excess water (E<sub>w</sub>)''. Excess water is divided between runoff (R<sub>o</sub>) and recharge to groundwater (R<sub>e</sub>) based on a baseflow index parameter ''(BFI)''. The BFI may be derived through a calibration process or estimated from data by performing a baseflow separation on a river flow time-series. Surface runoff and recharge to groundwater are calculated using equations 2.1 and 2.2:		Within SLiM, rainfall that isn’t evaporated, or doesn’t contribute directly to runoff, can be either intercepted by plants or reach the ground surface and infiltrate into the soil. The latter has the effect of increasing near surface soil storage and reducing the soil moisture deficit ''(SMD)''. Soil water can be extracted by plant roots for transpiration or drawn to the bare soil surface for evaporation. When soil moisture reaches field capacity and is unable to store further additions of water, water drains freely in the saturated soil. At field capacity if there are additional water inputs, lateral runoff (routed by Lisflood) occurs if a gradient exists towards adjacent locations. If the rainfall intensity is greater than the capacity of soil to maintain infiltration, water accumulates on the soil surface and becomes surface runoff. Water not accounted for in soil storage, evapotranspiration or uptake by vegetation is termed ''excess water (E<sub>w</sub>)''. Excess water is divided between runoff (R<sub>o</sub>) and recharge to groundwater (R<sub>e</sub>) based on a baseflow index parameter ''(BFI)''. The BFI may be derived through a calibration process or estimated from data by performing a baseflow separation on a river flow time-series. Surface runoff and recharge to groundwater are calculated using equations 2.1 and 2.2:

	[[Image:OR14011equation2.1a.jpg\|~~left~~\|~~500px~~\| ]]		[[Image:OR14011equation2.1a.jpg\|center\|700px\| ]]
	<br>		<br>
	[[Image:OR14011equation2.2.jpg\|left\|150px\| ]]		[[Image:OR14011equation2.2.jpg\|left\|150px\| ]]

Ajhil: /* Water partitioning component */

2022-04-20T09:46:47Z

Water partitioning component

← Older revision		Revision as of 10:46, 20 April 2022
Line 11:		Line 11:
	Within SLiM, rainfall that isn’t evaporated, or doesn’t contribute directly to runoff, can be either intercepted by plants or reach the ground surface and infiltrate into the soil. The latter has the effect of increasing near surface soil storage and reducing the soil moisture deficit ''(SMD)''. Soil water can be extracted by plant roots for transpiration or drawn to the bare soil surface for evaporation. When soil moisture reaches field capacity and is unable to store further additions of water, water drains freely in the saturated soil. At field capacity if there are additional water inputs, lateral runoff (routed by Lisflood) occurs if a gradient exists towards adjacent locations. If the rainfall intensity is greater than the capacity of soil to maintain infiltration, water accumulates on the soil surface and becomes surface runoff. Water not accounted for in soil storage, evapotranspiration or uptake by vegetation is termed ''excess water (E<sub>w</sub>)''. Excess water is divided between runoff (R<sub>o</sub>) and recharge to groundwater (R<sub>e</sub>) based on a baseflow index parameter ''(BFI)''. The BFI may be derived through a calibration process or estimated from data by performing a baseflow separation on a river flow time-series. Surface runoff and recharge to groundwater are calculated using equations 2.1 and 2.2:		Within SLiM, rainfall that isn’t evaporated, or doesn’t contribute directly to runoff, can be either intercepted by plants or reach the ground surface and infiltrate into the soil. The latter has the effect of increasing near surface soil storage and reducing the soil moisture deficit ''(SMD)''. Soil water can be extracted by plant roots for transpiration or drawn to the bare soil surface for evaporation. When soil moisture reaches field capacity and is unable to store further additions of water, water drains freely in the saturated soil. At field capacity if there are additional water inputs, lateral runoff (routed by Lisflood) occurs if a gradient exists towards adjacent locations. If the rainfall intensity is greater than the capacity of soil to maintain infiltration, water accumulates on the soil surface and becomes surface runoff. Water not accounted for in soil storage, evapotranspiration or uptake by vegetation is termed ''excess water (E<sub>w</sub>)''. Excess water is divided between runoff (R<sub>o</sub>) and recharge to groundwater (R<sub>e</sub>) based on a baseflow index parameter ''(BFI)''. The BFI may be derived through a calibration process or estimated from data by performing a baseflow separation on a river flow time-series. Surface runoff and recharge to groundwater are calculated using equations 2.1 and 2.2:

	[[Image:OR14011equation2.1a.jpg\|left\|~~150px~~\| ]]		[[Image:OR14011equation2.1a.jpg\|left\|500px\| ]]
	<br>		<br>
	[[Image:OR14011equation2.2.jpg\|left\|150px\| ]]		[[Image:OR14011equation2.2.jpg\|left\|150px\| ]]

Ajhil: /* Water partitioning component */

2022-04-20T09:45:25Z

Water partitioning component

← Older revision		Revision as of 10:45, 20 April 2022
Line 11:		Line 11:
	Within SLiM, rainfall that isn’t evaporated, or doesn’t contribute directly to runoff, can be either intercepted by plants or reach the ground surface and infiltrate into the soil. The latter has the effect of increasing near surface soil storage and reducing the soil moisture deficit ''(SMD)''. Soil water can be extracted by plant roots for transpiration or drawn to the bare soil surface for evaporation. When soil moisture reaches field capacity and is unable to store further additions of water, water drains freely in the saturated soil. At field capacity if there are additional water inputs, lateral runoff (routed by Lisflood) occurs if a gradient exists towards adjacent locations. If the rainfall intensity is greater than the capacity of soil to maintain infiltration, water accumulates on the soil surface and becomes surface runoff. Water not accounted for in soil storage, evapotranspiration or uptake by vegetation is termed ''excess water (E<sub>w</sub>)''. Excess water is divided between runoff (R<sub>o</sub>) and recharge to groundwater (R<sub>e</sub>) based on a baseflow index parameter ''(BFI)''. The BFI may be derived through a calibration process or estimated from data by performing a baseflow separation on a river flow time-series. Surface runoff and recharge to groundwater are calculated using equations 2.1 and 2.2:		Within SLiM, rainfall that isn’t evaporated, or doesn’t contribute directly to runoff, can be either intercepted by plants or reach the ground surface and infiltrate into the soil. The latter has the effect of increasing near surface soil storage and reducing the soil moisture deficit ''(SMD)''. Soil water can be extracted by plant roots for transpiration or drawn to the bare soil surface for evaporation. When soil moisture reaches field capacity and is unable to store further additions of water, water drains freely in the saturated soil. At field capacity if there are additional water inputs, lateral runoff (routed by Lisflood) occurs if a gradient exists towards adjacent locations. If the rainfall intensity is greater than the capacity of soil to maintain infiltration, water accumulates on the soil surface and becomes surface runoff. Water not accounted for in soil storage, evapotranspiration or uptake by vegetation is termed ''excess water (E<sub>w</sub>)''. Excess water is divided between runoff (R<sub>o</sub>) and recharge to groundwater (R<sub>e</sub>) based on a baseflow index parameter ''(BFI)''. The BFI may be derived through a calibration process or estimated from data by performing a baseflow separation on a river flow time-series. Surface runoff and recharge to groundwater are calculated using equations 2.1 and 2.2:

	[[Image:OR14011equation2.1.jpg\|left\|150px\| ]]		[[Image:OR14011equation2.1a.jpg\|left\|150px\| ]]
	<br>		<br>
	[[Image:OR14011equation2.2.jpg\|left\|150px\| ]]		[[Image:OR14011equation2.2.jpg\|left\|150px\| ]]