Download Rainfall Data (Hourly, Daily, Monthly, Yearly), Data Processing & Map Preparation in ArcGIS

Introduction

This tutorial will guide you through the process of downloading rainfall data from the CHRS Data portal for various time intervals, including hourly, daily, monthly, and yearly. Additionally, we will cover how to process this data and create an Average Annual Rainfall Map using ArcGIS. This guide aims to provide you with the necessary steps to obtain and visualize rainfall data effectively.

Step 1: Access the CHRS Data Portal

• Open your web browser and navigate to the CHRS Data portal.
• Register for an account if you do not have one. This is typically free and gives you access to downloadable data.
• Once logged in, familiarize yourself with the layout of the portal.

Step 2: Select Rainfall Data

• Locate the section for rainfall data within the portal.
• Choose the type of data you need based on the time interval:
  • Hourly
  • Daily
  • Monthly
  • Yearly
• Click on the desired option to view available datasets.

Step 3: Download the Data

• After selecting the desired rainfall data, look for a download button or link.
• Choose the file format that suits your requirements (e.g., CSV, GeoJSON).
• Confirm the download and save the file to your computer.

Step 4: Prepare Your Data for ArcGIS

• Open the downloaded file in a spreadsheet application (like Excel) to inspect the data.
• Ensure that the data is clean and structured properly:
  • Remove any unnecessary columns or rows.
  • Check for and address any missing values.
• Save the cleaned data in a compatible format for ArcGIS (e.g., CSV).

Step 5: Import Data into ArcGIS

• Launch ArcGIS on your computer.
• Create a new project or open an existing one where you wish to work with the rainfall data.
• Use the “Add Data” button to import your cleaned data file into ArcGIS.
• Verify that the data appears correctly in the map view.

Step 6: Create an Average Annual Rainfall Map

• In ArcGIS, use the tools to convert your data into a raster format if it’s not already.
• Follow these steps:
  • Open the Geoprocessing Toolbox.
  • Search for the “Zonal Statistics” tool.
  • Set the input raster and the zone data (your rainfall data).
  • Choose to calculate the average.
• Run the tool and wait for the processing to complete.

Step 7: Visualize Your Map

• Once the average annual rainfall map is generated, adjust the symbology:
  • Right-click on the layer and select “Symbology.”
  • Choose a color ramp that effectively represents the rainfall data.
• Add necessary map elements such as legends, scale bars, and titles.

Conclusion

You have successfully downloaded rainfall data, processed it, and created an Average Annual Rainfall Map using ArcGIS. This step-by-step guide should empower you to work with rainfall data for your projects. As a next step, consider exploring additional GIS tools or datasets to expand your analysis capabilities. Happy mapping!