Guide to NLOAD

Beginning at the NLOAD home page (http://nload.mbl.edu), click on "Log in to continue" to enter the site.

At the log in page enter your username and password and "Enter" the site. New users should click on "Create a new account." It is necessary to create an account so that each user can save their datasets and model results.

On the new account page you must choose a user name and password and provide your e-mail address in order to create an account. We also ask that you provide us with your address/professional affiliation, and tell us how you heard about NLOAD. Any information you can take the time to give us will be greatly appreciated. After entering the information, click the "Submit" button. This will bring you back to the log in page where you can immediately log in with your new user name and password, and "Enter" the site.

After logging in you are brought to a page that provides an overall description of NLOAD. At this point you may wish to click on one of the links to read more about nitrogen loading to estuaries, or click on "Continue."

This brings you to the NLOAD main menu. Clicking on "Background information" allows you to read additional information on N loading to estuaries, sources of N to coastal watersheds, forms of N, and the N cycle. Notice that any time a reference is cited on the NLOAD site you can click on that reference to get the full citation. "Guide to NLOAD" gives the user another chance to access this guide. "Carry out tasks" is the main module of the site, which runs the various models, and will be described in detail below. "Saved datasets" provides the user with a list of all the datasets they have saved in NLOAD, and gives the user the opportunity to delete any datasets they no longer want. "Model comparison table" brings you to a table listing all of the models currently available in NLOAD, as well as the reference for each model (click on the reference to get the full citation), the number of required user inputs, whether the model predicts N load to the estuary or N concentration in the water, and the form of N predicted. "Acknowledgments" brings you to a list of all the people involved in the creation of NLOAD, and acknowledges our funding sources. "NLOAD Home" brings you back to the home page, and gives you the opportunity to re-enter the site with your current username, or log in as a different user.

From the NLOAD main menu, click on "Carry out tasks" to begin selecting and working with the models. NLOAD is designed so that instead of simply selecting a model from a list, the user decides which question regarding N loading to estuaries they would like to address, and the program leads the user to models which are appropriate for answering that question. The first five questions deal with measuring the N load to an estuary, the next two questions address the concentration of N in the water, and the last question estimates the N exported from an estuary to offshore waters. Note that the seventh question, "Estimate the mean annual concentration of N in an estuary" is needed to calculate Total Maximum Daily Loads (TMDLs).

As an example, click on the first question to "Estimate the total N load from a watershed to a receiving water body." You are then asked what form of nitrogen you are interested in estimating. NLOAD has models available to answer this question that would predict either the "total dissolved nitrogen load" or the "nitrate load." At this point NLOAD also provides you the option of clicking on the link at the bottom of the page to go back and read more about the different forms of nitrogen.

Click on "total dissolved nitrogen load" and you will see the list of models that NLOAD has available to estimate the total dissolved nitrogen (TDN) load from a watershed to a receiving water body. The models are listed in order of increasing number of required user inputs. You can click on the various models to see the user inputs required to run the model (then simply use the "back" button on your web browser to return to this list if you choose not to use the selected model).

Click on "NLM - Nitrogen Loading Model," this will bring you to the page on which you can enter information for NLM. If you click on "Nitrogen Loading Model" at the top of the page you will get a pop-up window which gives the citation for the paper which fully describes the model, as well as a short description of NLM.

Back on the NLM input page you will see that toward the top of the page there is a button labeled "Unit converter." Click on the button to get a pop-up unit converter which will allow you to convert the units of your data to those necessary for model input. Below the unit converter is a drop down menu which stores all of the input datasets you have saved for this model. If you have not previously saved datasets for NLM, the drop down menu will not appear and this space will read "you have no saved datasets for this model." If you scroll to the bottom of this page, you will see a button labeled "Save Data." After you have entered all of the necessary information for NLM, pressing this button will prompt you to name this set of inputs, so that the next time you come to the NLM input page this dataset will appear under the drop down menu. When you select that dataset from the drop down menu the input page will automatically fill in with your saved data.

Below the drop down menu you will see a list of required user inputs. Each of these values must be filled in (with the correct units) in order to run the model. Below the list of inputs you can click to show (or hide) the default values for the model. Any of the values in the default list can be changed if you have more appropriate local data.

At the bottom of the input page, the "Reset" button will clear all of your inputs, and reset all default values. The "Save Data" button will give you the option of naming and then saving the values just entered, so that next time you access this page that dataset will appear under the drop down menu at the top of the page, and automatically fill in the page when selected. The "Run Nitrogen Loading Model" button will run the model and bring you to the NLM output page.

The model results appear on the NLM output page. It is also possible to click and be reminded of the model input and default values, as well as the intermediate model calculations. At the bottom of the page you have three options for saving your results, you can save as a Microsoft Excel spreadsheet, tab separated values, or comma separated values. All of these options will save model results, inputs, default values, and intermediate calculations. The "Save Data" option at the bottom of the page gives you another chance to name and save your model inputs (this is not necessary if you already saved your values on the model input page).

At the bottom of the model output page you can also "proceed to management options" or "use the results to predict the concentration of N in an estuary." If you click on "use the results to predict the concentration of N in an estuary," you will start the model process over, so that you are now addressing the question "Estimate the mean annual concentration of N in an estuary." You will go through the same selection process as above to choose a model and enter your data - in this case you will need your output from NLM as a model input.

If you choose to "proceed to management options," this brings you to a section of the website devoted to a discussion of various management options available to lower nitrogen loading to estuaries, and nitrogen concentration in estuarine water. In the discussions of the various management options we tell you specifically which input or default line items need to be changed to simulate the chosen management option. In these discussions we direct users to change line items in NLM and ELM, you can apply the discussion to other models as you see fit. Now you can go back and rerun the models to simulate a range of possible future scenarios based on various management decisions.