Category Archives: Geoscience Blog

Working with groundwater data using Arc Hydro Groundwater and ArcGIS Groundwater Toolset: An overview of the steps to study water levels in wells around an aquifer

Hydrological analysis using GIS requires that several aspects of the water cycle – occurrence, movement, and their relationship with the environment – be understood and addressed. Hydrology includes the study of surface and groundwater. Surface water has been understood well over the years and tools and models are available. However, groundwater has not been so well understood as for this, hydrogeological aspects also need to be incorporated.

ArcGIS from ESRI provides the tools for hydro analysis. ArcHydro is a set of data models and tools that allow you to study surface and groundwater. Surface water can be studied using ArcGIS Hydrology Toolset or ArcHydro. For Groundwater, use ArcHydro Groundwater (that has been developed by AQUAVEO and ESRI) or ArcGIS groundwater toolset (that is part of ArcGIS). Use ArcHydro Groundwater to:

  • Create maps depicting water  levels, water quality, etc
  • Create and visualize both 2D  and 3D geologic models and subsurface analysis

Use ArcGIS Groundwater Toolset for Spatial Analysis (Darcy analysis, particle tracking, etc).

Here we will look at how to use Arc Hydro Groundwater to study wells around an aquifer and understand the water level
changes over time by generating time series plots of water level data for selected wells. For this the overall steps would include the following:

  • Importing a map of the area including aquifers
  • Importing well data
  • Mapping the feature type in ArcGIS Hydro to column names in the data imported
  • Filtering the well data to specific types of wells
  • Symbolizing the filtered wells
  • Assigning Hydro IDs
  • Importing time series data for water level measurements of a particular well at a particular time
  • Create relationship between column in data file and feature type in ArcGIS
  • Join the time series data to well data based on a field
  • Calculate the elevation as well depths are negative values
  • Find wells with transient data using Make Time Series statistics
  • Create graphs and Interpolate data to a raster to create map of water levels for specific period
  • Generate flow direction for the wells

The procedure with a few screen shots is discussed here. For an elaborate discussion and detailed procedures refer to the ESRI and AQUAVEO websites.

Importing a map of the area with aquifers

Map of Area with Aquifer

The tool bars for groundwater analysis

Importing well data

Import Groundwater Data (in this case water wells in the selected area)

Mapping the feature type in ArcGIS Hydro to column names in the data imported

The field data collected must be in text files, spreadsheets, or supported formats. Although, various data can be collected the Arc Hydro data model will have a few features to which the collected data must be mapped. This data is specified by the Arc Hydro Framework and research is underway to improve the models.

Note that these wells have a state well number, associated aquifer code, and names of owners that helps in managing groundwater.

Filtering the well data to specific types of wells

Wells can be classified on different parameters and labeled accordingly. For example, wells can be for monitoring, agricultural, or drinking water purposes or can be classified according to the geology – sandstone aquifer wells, igneous wells, etc.

Assigning Hydro IDs

Hydro features are identifiers of hydrological and hydrogeological components. Hydro ID is unique across the geodatabase that is needed to build a model of the well or aquifer. Hydro Code is also unique and describes the features in an external data source. This is a key step.

Importing time series data for water level measurements of a particular well at a particular time and Creating relationship between column in data file and feature type in ArcGIS

Join the time series data to well data based on a field

We have already imported well data and symbolized it. Next for analysis, a second parameter is required. For this we imported time-based data as the purpose is to study water levels over time. Next we join the time series data collected at the particular well to the well data. This is where the Hydro ID is useful as it is unique.

Calculate the elevation as well depths are negative values

Remember that wells are beneath the surface and is assigned negative values. However, this needs to be “normalized” for calculation and for meaningful inference of the data. This is done using the elevation and time series values.

Find wells with transient data using Make Time Series statistics

Now that you have well data and time series data and assigned unique Hydro IDs, you can do further analysis. One of the important tasks is to separate out the wells without time-bound data. This happens as some wells might have gone dry or simply data might not have been captured or the wells might not be significant for the study.

Wells with transient data

You can use the Make Time Series statistics tool to find features such as wells with transient data for specific periods.

Analysis

Creating graphs: Graphical representations help you study the selected wells and make decisions. You can use the Time Series Grapher to do this.

Interpolating data to raster catalog: you can create raster maps such as water level maps for future use using the Spatial Analyst tools.

Generate flow direction for the wells: you can find out the direction of water flow using the flow direction generator tool. This helps in identifying the downward gradient and where water flows into.

Flow direction of water is downhill

This concludes the overview of the steps to study water levels in wells around an aquifer.

A flock of cranes (of the mechanical kind)

For those who work in onshore and offshore rigs, ports, tall building construction sites, and generally in any structural and construction engineering projects, cranes might be an everyday occurence. In Chennai, there has recently been a lot of construction activities and cranes are being used a lot. These may not be massive projects compared to those in the USA, China, or elsewhere – but this does seem interesting to those who have never seen big machines before.

Here are some photographs of different cranes:

  • A hammer-head tower crane at work on a building construction site
  • A crawler-mounted Latticework Boom Crane with a clamp shell bucket for dredging out the sediment at a desalination plant construction site near Muthukadu on ECR at Chennai
  • A wheel-mounted standard crane with rotating operator’s cabin that is used when construction has to take place within a limited area. These cranes are used for building the “Chennai Metro Rail” and the construction has to take place amid heavy traffic. I did not find enough safety mechanisms but the city is so populous and there is hardly any alternative travel route for people
  • A modified overhead gantry (hoist) on a beam to move each concrete block into place on the overhead road bridge. The roads seem so full what with a large storage of scaffoldings, hooks, sockets, shackles, wire ropes, chains, slings and hitches, rods, concrete and other equipment close to the places of construction

I included this post in this blog as there is some geo-engineering involved in the form of soil-testing, feature mapping, dredging, drilling, etc … and more so because I get excited by cranes 😉

Hope the cranes can lift us to a less-congested future.

Geomorphology of Adyar River estuary, Chennai, India

The Adyar river drains into the Bay of Bengal and forms an estuary behind the Theosophical Society near MRC Nagar, Chennai.  Small dunes are visible and thick alluvium covers the Archaen rocks. The river supplies sediment heavily to continually alter the geomorphology of the unique environment. A broken bridge adds a bit of drama to the landscape.  Would be interesting to see how much the 2004 Indian Ocean Tsunami has altered the features. The estuary is small but can probably be classified as a depositional and semi-lagoon spit type.

Niagara falls – river erosion at work

The Niagara Falls -mesmerizing and powerful was formed a million years ago after the Ice age. The huge volume of water empties into Lake Ontario. The rock type of the area is Shale – Rochester Shale. Erosion reveals Dolomite and other sedimentary rock formations. Silurian age fossils are typical of this area.

Hyderabad Rock Formations (Gneiss and Granite)

Hyderabad – situated in India is part of the Deccan plateau. The area is full of spectacular rock formations – toadstools, mushroom rocks, hanging monsters, and turtle back. These rocks were formed probably 2.5 billion years ago.

Earth formed about 4.5  billion years ago. The surface of the Earth solidified about 3.5 billion years ago (when water too appeared as seas). About 2.5 billion years ago, some molten magma oozed on to the surface (Earth crust) in typical “Deccan lava flow” fashion. Much molten magma however probably pushed up the crust but cooled beneath the crust (which could have been thicker then due to lesser time of weathering) unable to push anymore.  The magma formed granitic domes, sheets, and stocks or massive intrusive batholiths.

Later through Precambrian and Cambrian the crust underwent weathering and eroded exposing the Granite beneath. The Granite developed horizontal and vertical cracks and were weathered to their present spectacular forms.

Some photos of the landscape near the airport.

 

Abandoned Gypsum Mine, Seegrotte, Austria

This is an abandoned Gypsum mine close to Vienna, Austria. For details see: http://www.seegrotte.at/index.php?id=6&L=1

You can see textbook images of piles, stacks, trolley, etc. The underground lake is amazing too.

Geology Books Collection

I have a fantastic collection of books on Geology. I am going to review a few and hopefully one day after I retire start a library on Geological books and rock collections.

Vesuvius – lava rivers, caldera, and ash

Volcanoes – fiery or silent – always inspire awe. However many times you may have read about volcanoes, the feeling – when you are near the cone is – great. Here are a few pictures of the Vesuvius in Italy.

Photos of “Ice Caves” at Werfen – Austria

Greetings! In this first entry I enclose a few photographs from a trip to the eastern Alps. This place has amazing geology and the views are spectacular. A natural cave system is a popular attraction here. It was amusing to see shops selling “minerals” and “rock ore” such as Amazonite, Pyrite, Quartzite, etc.

Cave Opening p1010009.jpg p1010019.jpg p1010001.jpg

Welcome to the Geocene blog

Hi all, welcome to the blog of www.geocene.net. Here you will find opinions, thoughts, personal logs, and information related to Geology.  Invited authors will write short pieces (blog entries) on Geology. Readers can leave their comments or contact the authors directly. These entries/content are the opinions of the authors and we at www.geocene.net or http://blogatgeocene.net do not assume responsibility for the posts.

 This blog we hope acts as a common forum for both authors and readers alike and along with the website www.geocene.net brings together the Geoscience community.

Again a warm welcome to all and happy blogging!

Cheers,
Editor

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