Calibration/Validation in Mohid Land - Revision history

Davidbrito: /* Model is delayed */

2013-07-01T15:50:51Z

‎Model is delayed

Davidbrito: /* Step 3 - Validate floods (surface water) */

2012-08-30T16:07:14Z

‎Step 3 - Validate floods (surface water)

Davidbrito: /* Step 3 - Validate floods (surface water) */

2012-08-30T15:05:35Z

‎Step 3 - Validate floods (surface water)

Davidbrito: /* Resume */

2012-08-30T15:02:53Z

‎Resume

Davidbrito: /* Step 4 - Validate baseflow */

2012-08-30T15:01:56Z

‎Step 4 - Validate baseflow

Davidbrito: /* Step 3 - Validate floods (surface water) */

2012-08-30T15:01:26Z

‎Step 3 - Validate floods (surface water)

Davidbrito at 16:03, 29 August 2012

2012-08-29T16:03:14Z

Davidbrito: /* Model Baseflow is low and falls fast */

2012-08-29T11:55:30Z

‎Model Baseflow is low and falls fast

Davidbrito: /* Flood Fall */

2012-08-29T11:47:45Z

‎Flood Fall

Davidbrito: /* Flood Fall */

2012-08-29T11:47:03Z

‎Flood Fall

← Older revision		Revision as of 15:50, 1 July 2013
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	2 - Usually the first floods because soil is dry (or drier) do not occur from saturation excess or infiltration excess (if not really high intensities) but impermeabilization is the main control factor. So if the watershed is urban it should be described the impermeable fraction and the storm water structures; if the watershed is rural than impermeability may occur beacause of soil sealing.		2 - Usually the first floods because soil is dry (or drier) do not occur from saturation excess or infiltration excess (if not really high intensities) but impermeabilization is the main control factor. So if the watershed is urban it should be described the impermeable fraction and the storm water structures; if the watershed is rural than impermeability may occur beacause of soil sealing.
		+
		+	Also the drainage network may have low resolution (only main rivers are described) and in reality concentrated flow (flow that occurs concentrated in a width lower than cell size) may occurr. So, before anything increase your drainage network resolution and see if the first peaks start to appear. If yes it means that in reality exists concetrated flow inside the cells that can only be simulates with drianage network (by the way that was the reason why drainage network module was created, because if the DTM and cell resolution were of the order of 1m or less there was no need for it).
		+

	'''Parameters:'''		'''Parameters:'''

@@ Line 119: / Line 119: @@
 - storm water velocity - water velocity in storm water drainage system
-===Second Floods===
+===Floods After Soil Saturation===
 As stated above second floods or floods after soil is saturated are less dependent on impermeabilization factor (soil is behavinf already as impermeable) and evapotranspiration is the controling factor since it may increase or decrease soil water content and its ability to infiltrate more or less water that will not get into the river.

← Older revision		Revision as of 15:05, 30 August 2012
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	- Feddes Heads		- Feddes Heads
−

	===Flood Fall===		===Flood Fall===

@@ Line 1: / Line 1: @@
 ==Resume==
-This page was written intended to give the main insights to calibration/validation in Mohid Land for hydrology. Since the model is physically based the main "calibrations" are linked to giving the model the right precipitation, evapotranspiration, geometry in sections or impermeability matrix representing the area available for infiltration.
+This page was written intended to give the main insights to calibration/validation in Mohid Land for hydrology. Since the model is physically based the main guidances are linked to giving the model the right precipitation, evapotranspiration, geometry in sections or impermeability matrix representing the area available for infiltration.
 This section describes the steps for conducting a procedure for calibration and should be done sequencially since the first steps exist to assure that the last are fine tunings and not deviations needed to compensate the lack of work in the first steps.

← Older revision		Revision as of 15:01, 30 August 2012
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	==Step 4 - Validate baseflow==		==Step 4 - Validate baseflow==
		+	Important: Remind that if changing this parameters it may change evapotranspiration and river flow and after this step the long term validation discussed in the section 3 should be redone.
		+
	After the flood rise and fall (surface water) the most of the water that arrives in river is from groundwater, because aquifer rise as response to rain but the velocity in porous media is much slower so the water arrives to the river after the surface water.		After the flood rise and fall (surface water) the most of the water that arrives in river is from groundwater, because aquifer rise as response to rain but the velocity in porous media is much slower so the water arrives to the river after the surface water.

@@ Line 72: / Line 72: @@
 ==Step 3 - Validate floods (surface water)==
 After rain check (in long term and flood periods) in first step and evapotranspiration/river flow check for long term (annual, monthly) than model is predicting the right amount of evapotranspiration and river flow for monthly analysys. However for floods that may even rise and fall in one day additional calibration may be needed.
 ===Flood Rise===
@@ Line 113: / Line 118: @@
 - storm water velocity - water velocity in storm water drainage system
 ===Flood Fall===

@@ Line 13: / Line 13: @@
 - Validate groundwater flow that has it most component after the flood (after aquifer rise and transport trough the porous media)
-==Before you start==
+==Before starting==
 Model lack of accurancy usually is simpton of three things:
@@ Line 35: / Line 35: @@
 In the next chapters it will be addressed the calibration/validation method that should be used, assuming that in terms of DTM, soil and land use map the user is using the best available data.
-==Step 1 - Validate your rain and meteorology==
+==Step 1 - Validate rain and meteorology==
-Since rain is the main driver of the water cycle, data gaps or data errors will compromise your results. For example if you are looking to simulate floods there can not be a flood in the model if it does not rain in that period, or model will generate really high floods if abnormally high rain is inputed.
+Since rain is the main driver of the water cycle, data gaps or data errors will compromise results. For example if looking to simulate floods there can not be a flood in the model if it does not rain in that period, or model will generate really high floods if abnormally high rain is inputed.
 It is very important that the rain used for feeding the model is the best one. And the best is the rain that represents the rain regime and events occured in the watershed. With that said it is important that if the watershed has areas with higher rain intensity or lower that they are represented by rain stations so that the difference will be taken in account by the model.
-So '''What stations to use and how to trust in your data?'''
+So '''What stations to use and how to trust in data?'''
 The first things to do is to look at rain stations. Collect all the data in the watershed but also in neighbour watersheds and do annual and monthly accumulations of data with the number of sampling days per month and per year. When graphing the accumulated annual and monthly precipitations, the stations (or periods) with bad data will pop up trough low sampling days or curves in graphs that are not correlated to other stations.

@@ Line 160: / Line 160: @@
 '''Solution:'''
-The groundwater flow needs to be enhanced. Mohid Land computed groundwater flow based on the Hydraulic gradient between river level and aquifer level and the aquifer level is computed up to where saturation occurs. Model has cells and fluxes between cells (specially in periods of high flows) may lead to a situation of soil very near saturation but not completly saturated and so the aquifer level is artificailly lowered so as the flux between river and soil.
+The groundwater flow needs to be enhanced. Mohid Land computes groundwater flow based on the Hydraulic gradient between river level and aquifer level and the aquifer level is computed up to where saturation occurs. Model has cells and fluxes between cells (specially in periods of high flows) may lead to a situation of soil very near saturation but not completly saturated and so the aquifer level is artificailly lowered so as the flux between river and soil.
-Give a water content range to assume saturation to check for groundwater level and to compute flux between soil and river.
+Give a water content range - from saturation - to check for groundwater level. The default value is 1E-15 difference to saturation water content that creates a high aquifer level fluctuation (an mainly reduction).
 '''Parameters:'''
-- groundwater level range for saturation - range from saturation to assume saturation when searching for aquifer level.
+- groundwater level range for saturation - range from saturation point when searching for aquifer level.
 - horizontal conductivity factor - horizontal conductivity multiplying factor (multiplying for cell computed conductivity).
 ==Links==
 [[Mohid Land]]

← Older revision		Revision as of 11:47, 29 August 2012
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	- Channel manning		- Channel manning
		+
		+	- Section geometry (including bottom slope that is not a parameter but computed from adjacent nodes bottom levels).

	==Step 4 - Validate baseflow==		==Step 4 - Validate baseflow==

← Older revision		Revision as of 11:47, 29 August 2012
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	- Channel manning		- Channel manning
		+
		+	- Section geometry (including bottom slope that is not a parameter but computed from adjacent nodes bottom levels).

	====Model has a slower decay====		====Model has a slower decay====