Groundwater Overlay: Difference between revisions

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The groundwater overlay is an implementation of the [[Water Overlay]] optimized for calculating the flow of underground watertables. This implementation focuses on water flowing at a low speed, and on the functioning of the water system without calamitous events such as [[Water Overlay#Breach|breaches]].
{{Water Overlay
 
|name=groundwater overlay
==Use cases==
|optimized=calculating the flow of underground watertables
The groundwater overlay can be used and is recommended when exploring the following use-cases:
|focus=water flowing at a low speed, and on the functioning of the water system without calamitous events such as breaches
|use-cases=
* Modeling a static, low-speed water system
* Modeling a static, low-speed water system
* Modeling the long-term effects of excessive rain or excessive drought on the water table
* Modeling the long-term effects of excessive rain or excessive drought on the water table
* Modeling the spread of chemicals through the underground, carried along by water
* Modeling the spread of chemicals through the underground, carried along by water
 
|preparation=It is important to model a fully functional static water system for any relevant use of the overlay. After setting up the static water model, additional effects can be modeled to account for special circumstances. This has the added benefit of creating a control-state, to which results of modifications or calamities can be compared.
==Preparing to use the overlay==
|sim-time-recommendation=weeks or months
{{Water Overlay|how to use=1}}
|extra-steps=yes
 
|
It is important to model a fully functional static water system for any relevant use of the overlay. After setting up the static water model, additional effects can be modeled to account for special circumstances. This has the added benefit of creating a control-state, to which results of modifications or calamities can be compared.
|water-level-areas=Required
 
|groundwater=Recommended
===Prerequisites===
|weirs=Required
{{Water Overlay|prerequisites=1}}
|culverts=Required
 
|pumps=Required
===Data===
|inlets=Required
It is advised to prepare the data you wish to use in your model before creating and configuring the overlay. Strictly, it is possible to use the overlay without preparing all or any of the data, however the accuracy and usefulness of the model is directly proportional to the preparation of data.
|sewer-areas=Optional
 
|sewer-overflows=Optional
Not all data is equally important. When prioritizing the preparation of data, you may choose to prioritize some data over other, in which case the importances listed below can offer a guideline.
|chemicals=Required
 
|chemicals-alt=Optional
Most data can be loaded in directly in the wizard. Some data should be loaded in separately either before or after stepping through the wizard.
|
 
|sim-time=Required
====Geographical data====
|timeframes=Recommended
Geographical data needs to be prepared, so that it can be loaded in and used by the water model's calculations. This data will form hydrological features and constructions which interact with the hydrological model.
|Evaporation=Recommended
 
|Rain=Optional
If a type of data does not exist for your project area, either because the data components do not exist in the project area or because the data is unavailable, it is possible to skip that kind of data while preparing. Generally, the more closely the data (and the water model) resembles the real world situation, the more accurate the model will be.
|
{{OverlayChecklist|table=true}}
|SURFACE_LAST_VALUE=Required
{{OverlayChecklist|Water areas|link=Water Overlay#Water_area|
|UNDERGROUND_LAST_VALUE=Required
  importance=Required for proper water levels|
|SURFACE_FLOW=Recommended
  load=Wizard|
|EVAPORATED=Recommended
  description=Water areas set the water level of all open water in the area they envelop.}}
|UNDERGROUND_WATERTABLE=Optional
{{OverlayChecklist|Ground water|link=Water Overlay#Groundwater_geotiff|
|SUBSTANCES=Required
  importance=Recommended for proper water levels|
  load=Wizard|
  description=The ground water geotiff sets the underground water level.}}
{{OverlayChecklist|Weirs|link=Water Overlay#Weir|
  importance=Required for proper water flow|
  load=Wizard|
  description=Weirs connect otherwise separate sections of open water, allowing water to flow over the weir.}}
{{OverlayChecklist|Culverts|link=Water Overlay#Culvert|
  importance=Required for proper water flow|
  load=Wizard|
  description=Culverts connect otherwise separate sections of open water, allowing water to flow through the culvert.}}
{{OverlayChecklist|Pumps|link=Water Overlay#Pump|
  importance=Required for proper water flow|
  load=Wizard|
  description=Pumps connect otherwise separate sections of open water, moving water unidirectionally from the lower terrain level to the higher terrain level.}}
{{OverlayChecklist|Inlets|link=Water Overlay#Inlet|
  importance=Required for proper water quantities|
  load=Wizard|
  description=Inlets are points in the water model where water is added or removed from the hydrological system.}}
{{OverlayChecklist|Sewer areas|link=Water Overlay#Sewer|
  importance=Optional for proper water levels|
  load=Wizard|
  description=Sewer areas intersect with [[sewered]] [[constructions]] in the area they envelop to form sewers which can store water.}}
{{OverlayChecklist|Sewer overflows|link=Water Overlay#Sewer_overflow|
  importance=Optional for proper water flow|
  load=Wizard|
  description=Sewer overflows allow water to flow from a sewer to open water.}}
{{OverlayChecklist|Chemical producers/scrubbers|link=Water Overlay#Chemical_hotspots|
  importance=Required for modelling chemical flows,<br>optional otherwise|
  load=Seperately|
  description=Chemical producers create some quantity of arbitrary chemicals (such as chloride, phosphorus, or nitrogen), which can then flow through the model.}}
{{OverlayChecklist|table-end=true}}
 
====Calculation properties====
Environmental and simulation parameters for the calculation need to be prepared, so that they can be loaded in and the simulation can compute results based on a specific case and intent. This data will influence how the simulation progresses in general.
 
It's possible to skip any of the configurations and fall back on default values offered. However, in general the results of a better configured overlay will produce more useful results.
{{OverlayChecklist|table=true}}
{{OverlayChecklist|Simulation time|link=Water Overlay#Simulation_time|
  importance=Required|
  load=Wizard|
  description=How long should the simulation last in total. Groundwater calculations often look at timespans of weeks or months.}}
{{OverlayChecklist|Timeframes|link=Water Overlay#Timeframes|
  importance=Recommended|
  load=Wizard|
  description=How many result snapshots should be generated by the calculation, for inspection after the calculation completes.}}
{{OverlayChecklist|Evaporation|link=Water Overlay#Evaporation|
  importance=Recommended|
  load=Wizard|
  description=How quickly water evaporates. For longer simulations with little water flowing in or out, evaporation can have a large effect over time.}}
{{OverlayChecklist|Rain|link=Water Overlay#Weather|
  importance=Optional|
  load=Wizard|
  description=How long should rain last at the start of the simulation, and how much rain should fall in total.}}
{{OverlayChecklist|table-end=true}}
 
====Result types====
A specific idea of what kind of results are relevant as output need to be prepared, so that the overlay can be configured to provide relevant results.
 
For use with this overlay, there are a number of suggested [[Water Overlay#Result_types|result types]] to consider.
{{OverlayChecklist|table=true}}
{{OverlayChecklist|SURFACE_LAST_VALUE|link=Water Overlay#SURFACE_LAST_VALUE|
  importance=Required for insight into amount of water|
  load=Wizard|
  description=The amount of water in any given location.}}
{{OverlayChecklist|UNDERGROUND_LAST_VALUE|link=Water Overlay#UNDERGROUND_LAST_VALUE|
  importance=Required for insight into amount of water|
  load=Wizard|
  description=The groundwater level rise in any given location.}}
{{OverlayChecklist|SURFACE_FLOW|link=Water Overlay#SURFACE_FLOW|
  importance=Recommended for insight into movement of water|
  load=Wizard|
  description=The flow of water across the land and water in total.}}
{{OverlayChecklist|EVAPORATED|link=Water Overlay#EVAPORATED|
  importance=Recommended for insight into water leaving the system|
  load=Wizard|
  description=The amount of water which evaporated in total.}}
{{OverlayChecklist|UNDERGROUND_WATERTABLE|link=Water Overlay#UNDERGROUND_WATERTABLE|
  importance=Optional for insight into groundwater|
  load=Wizard|
  description=The groundwater level in any given location, relative to {{datum}}.}}
{{OverlayChecklist|SUBSTANCE_A, SUBSTANCE_B, etc|link=Water Overlay#SUBSTANCE_A|
  importance=Required for insight into chemical flow and impact|
  load=Wizard|
  description=The amount of certain substances present in any location.}}
{{OverlayChecklist|table-end=true}}
 
==Adding and configuring the overlay==
{{Editor ribbon|header=current situation|bar=Overlays|dropdown=Groundwater overlay}}
 
The groundwater overlay can be added to the project, either by using the overlays dropdown in the editor ribbon, or by selecting the overlays editing option in the ribbon, and then opting to add it via the [[left panel]]. The overlay can then be configured using the [[Water Overlay#Configuration_wizard|configuration wizard]]. In general, if all steps in the configuration wizard are followed, no further editing outside of the wizard is required to configure the overlay.
 
{{Editor steps|title=use the groundwater overlay
|Check that your project sufficiently matches the stated {{inlink|prerequisites}}
|Make sure that you have prepared all {{inlink|data}} you wish to use
|Add the groundwater overlay to your project
|Start and follow the steps in the [[Water Overlay#Configuration_wizard|configuration wizard]]
|When the configuration wizard is completed, the overlay will automatically recalculate.
|Start the geo data wizard and load in any additional geographical data not considered during the wizard.
|When all data is loaded in, recalculate the overlay using [[refresh grid]].
|When the recalculation has completed, you can inspect the results
}}
}}
==Data analysis==
When the calculation has completed, results of the calculation inspected by selecting the overlay in the [[session interface]]. The quickest means of inspecting the results are listed here. For a more complete overview, see [[Water_Overlay#Result_analysis|result analysis]].
===Overlay map===
To check directly whether the model functions as expected, you can activate the overlay and see the end-results directly. If multiple [[Water Overlay#Timeframes|timeframes]] have been recorded, the results can be replayed, to see the progression of the results over time.
===Measurement tool===
To get more detailed measurements of the result, you can use the [[measuring tool]] to inspect the results of a specific cell. The measurement tool also allows for the saving and loading of locations of measurement, so that comparative measurements can be made between different overlays and different calculations.
===Water balance===
Besides directly inspecting the results geographically, when verifying the functioning of a hydrological model it can be insightful to check the [[Water Overlay#Water balance|water balance]]. This option allows a net tally of where water ends up in the hydrological system.
==Refining the model==
Based on the results from the initial calculation, you can tweak your data to refine your model. You can update your relevant datasets, and then step through the configuration wizard again.
{{Editor steps|title=refine the groundwater overlay
|Reopen the configuration wizard of the overlay
|In any step where you want to update your data, either change the individual values, or clear and reupload the data
|Skip through all steps which concern data you do not wish to change
|When the configuration wizard is completed, the overlay will automatically recalculate. (If it does not, select [[Grid_overlay#Grid_recalculation|refresh grid]].)
|If you have any additional data you wish to load in, open the [[geo data wizard]] and follow the steps.
|If you have any data you wish to modify, select the data in the editor and adjust the properties or attributes accordingly.
|When all data is loaded in, recalculate the overlay using refresh grid.
|When the recalculation has completed, you can inspect the results
}}
Every step where no data has changed can be skipped, and the dataset which has been uploaded can be reuploaded in the relevant step. Alternatively, you can do this directly by changing the relevant data in your project. For example, it is possible to directly change the [[attributes]] of [[constructions]].
===Common refinements===
{{stub|type=section}}
* '''Grid cell size''': Due to the complexity of the calculation and the strong impact the level of detail in the data can have, it is possible that an initial calculation yields inaccurate results. One way of increasing the accuracy of the results is to increase the [[grid cell size]].
* '''Ground water''': The functioning of groundwater is commonly strongly influenced not only by the groundwater level but also the [[Water Overlay#GROUND_BOTTOM_DISTANCE_M|assumed distance to the impenetrable layer]] below ground. That layer is effectively the lowest the groundwater level can be.
* '''Input overlays''': There is a lot of data which is pre-processed before actually used in the calculations. Some model behaviors can be better explained or reproduced with insight in how the model interprets geographical data in the project. This can be done by adding an [[Water Overlay#Input overlays|input overlay]] for that type of data.
===Saving the results===
If the results of the calculation provide a proper baseline hydrological model, the result of the overlay can be [[Grid_overlay#Save_overlay_result|saved]] as an inactive copy. This means that the overlay, including its direct settings and its results, are duplicated into a new overlay. The duplicate is then set to "inactive". This means the data in that overlay won't change as further changes are made. You can then set up a new scenario in your original overlay, and after performing another calculation compare the results of the first and the second situation.

Revision as of 12:21, 19 February 2019

Template:Water Overlay

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