# sw\_init All soils in the watershed will be initialized to the same fraction. If *sw\_init* = 0.0, the model will calculate it as a function of average annual precipitation. {% hint style="info" %} We recommend using a warm-up period of at least 1 year, i.e. start the simulation at least 1 year prior to the period of interest. This allows the model to get the water cycling properly before any comparisons between measured and simulated data are made. If a warm-up period is incorporated, the value for *sw\_init* will not impact model results. {% endhint %} --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://swatplus.gitbook.io/io-docs/introduction-1/basin-1/parameters.bsn/sw_init.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.