Wishlisted Wishlist

Please confirm that you want to add Basic Hydrology to your Wishlist.

Add to Wishlist

Basic Hydrology

Creating hydrologic models of small watersheds for conservation bmps, leveraging the power of GIS.
4.2 (103 ratings)
Instead of using a simple lifetime average, Udemy calculates a course's star rating by considering a number of different factors such as the number of ratings, the age of ratings, and the likelihood of fraudulent ratings.
3,035 students enrolled
Created by Tim Clark
Last updated 7/2015
  • 2.5 hours on-demand video
  • Full lifetime access
  • Access on mobile and TV
  • Certificate of Completion
What Will I Learn?
Compute peak runoff rates for rural watersheds
Compute peak runoff rates for urban watersheds
Delineate watersheds using maps and ground truthing
Understand the differences between the 3 most widely used hydrology models
View Curriculum
  • Need to be able to download and install NRCS software
  • Need to be able to download and install the HydroCAD Sampler
  • Have either ArcGIS Desktop Advanced with Spatial Analyst Extension, or the open source QGIS

This course teaches soil and water district technicians and junior engineers how to model small watersheds for conservation and stormwater management structures. Three hydrological models are presented: EFH2, TR-20/TR-55, and the rational method. The course includes a blend of GIS and by-hand analysis methods. For the GIS portions, parallel workflows are presented for ArcGIS (Spatial Analyst extension), and for QGIS. The EFH2 software is presented for rural hydrology while HydroCAD (Free Sampler edition) is used for urban projects. The course culminates in two design examples to allow students to implement what they've learned.

Who is the target audience?
  • Soil and Water District technicians with 0-2 years of experience
  • Entry level engineers working in transportation, civil/site, and agricultural disciplines
Students Who Viewed This Course Also Viewed
Curriculum For This Course
Expand All 20 Lectures Collapse All 20 Lectures 02:28:14
Hydrologic Modelling workflow
1 Lecture 12:34

Start here if you're not really sure what hydrology is or why you would use it. We'll also cover relevant documents for further study. Since we're using NRCS derived techniques, here are the links to NEH Part 630, which is described in the lecture.

Main Page: http://directives.sc.egov.usda.gov/default.aspx

Direct Link to Title 210:Part 630: http://directives.sc.egov.usda.gov/viewerFS.aspx?hid=21422

What is my drainage area?
6 Lectures 31:27

Mapping, or delineating a drainage area is the crucial next step once your design point is known. We'll start with some easy examples.

Drainage Area Mapping

Students will need an ArcMap basic license to follow along with this lesson. They will load a USGS topographic basemap and practice delineating drainage areas on it.

Drainage Areas in ArcMap

We'll add a USGS Topographic web map service to our map, and then create a new shapefile to represent a watershed.

Drainage Areas in QGIS

The course is targeted at Conservation District Employees in NY state, so let's look at getting LiDAR within the state.

Getting Lidar in New York State

If you're fortunate enough to have and ArcGIS advanced license and spatial analyst extension, you can follow along with these instructions and generate contours from lidar raster files.

Lidar Contours in ArcMap

QGIS has surface tools built in, so you'll be able to manipulate Lidar files right out of the box if you're going this route.

Lidar Contours in QGIS
How much water flows off the land?
4 Lectures 43:22

Curve numbers approximate how much rainfall will end up as runoff. They are determined by the land use and hydrologic group of the soil profile. Students will be able to determine CN values using their best judgment and published sources.

Curve Numbers (CN values)

Soil data is tricky to set up but definitely worth it. We'll cover all the steps needed to get it up and running.

Soil Data Viewer

Lets digitize land use areas in ArcMap, then intersect them with the hydrologic soil groups layer. Then we'll calculate areas and export the attribute table to excel. A simple pivot table in excel produces our results.

Curve Number Mapping in ArcMap

Lets digitize land use areas in QGIS, then intersect them with the hydrologic soil groups layer. Then we'll calculate areas and add them up using Group Stats QGIS plugin.

Curve Number Mapping in QGIS
How long does the water take to get to here?
4 Lectures 30:23

We need 3 variables to compute time of concentration for rural watersheds. Let's find out what they are!

Time of Concentration (Rural)

Here we'll learn how to compute the average watershed slope using the Advanced ArcMap Spatial Analyst extension.

Rural Tc in ArcMap

Here we'll learn how to compute the average watershed slope using QGIS built-in tools.

Rural TC in QGIS

This lecture shows how to compute the TC for urban watersheds, for use in HydroCAD.

Time of Concentration (Urban)
3 Lectures 27:40

EFH2 is a great free program for computing rural watershed hydrology. This lecture shows how to download, install, and use the program.


HydroCAD is a multi-purpose runoff and stormwater modelling platform. We'll just be scratching the surface of its capabilities by looking at the watershed hydrology portion.


We'll still be using HydroCAD but with an alternative hydrology model called the rational method. Nearly everything we've learned so far also applies to the rational method, but it uses different runoff coefficients and rainfall data, as well as a different governing formula.

HydroCAD using the Rational Method
Example Problems
2 Lectures 02:48

This short video introduces an example project. Written project instructions are included as supplemental material, as well as a pdf with answers and discussion.

"Rural Areas Export" is an excel spreadsheet with my areas aggregated by land use and hydrologic soil group.

The file, "EFH2 Rural Example.xml" needs to be renamed with a .efm extension. Udemy limits the allowed file extensions for lecture resources.

Rural Hydrology for a laneway culvert (With ArcGIS)

This short video introduces the project site. We'll be using the same site for a TR-20 analysis and Rational Method Analysis. Written project instructions and answers are included for both methods. There are 2 zipped shapefiles which contain the inlet and pipe locations. You will need to unzip them to load each shapefile into QGIS. There area also two HydroCAD files that contain completed models. These HydroCAD files have been uploaded as .xml files, because Udemy has strict limits on file types. You will need to change their extensions back to .hcp in order to run them in HydroCAD.

Urban Hydrology (With QGIS)
About the Instructor
4.3 Average rating
193 Reviews
5,391 Students
5 Courses
Conservation Planning, Design & Implementation across NY!

Tim is a NY State Registered Professional Engineer with a diverse background in agricultural conservation, civil/site design, railway design, aviation design, and highway design. He is currently the State Engineer for the New York State Soil and Water Conservation Committee housed at the NY State Department of Agriculture and Markets, where he is dedicated to improving the planning, design, and construction of conservation practices across New York State.

Report Abuse