Merge pull request #10 from storm-fsv-cvut/requirements

describe data, model limitations and hardware requirements

user_guide/docs/requirements.md

@@ -1,10 +1,45 @@
 # Requirements
-## Data requirements
-
-Data types
 
 ## Model limits and recommendation
+The limitations of the model lie in its mathematical representation of physical
+phenomena.
 
-## Hardware requirements
+SMODERP2D is an episodic model; therefore, it does not account for water
+redistribution in the soil. The model assumes continuous rainfall, which begins
+at the start of the calculation and ends a few minutes (or hours) before the
+conclusion. Although rainfall with varying intensity can be input, it must
+still be continuous. Gaps in the rainfall data would result in a
+misrepresentation of runoff and erosion.
+
+A reasonable spatial resolution is necessary for the model run properly. Each
+cell in the model represents a piece of land where a small brook could form or
+a rill could be created. Therefore, cells smaller than the width of a brook or
+rill would lead to a misrepresentation of hydraulic in such features.
+Conversely, cells that are too large would result in oversized brooks or rills,
+as only a single watercourse or rill can be represented in each cell. Thus, a
+cell size of 2 to 20 meters is recommended. It's important to note that the
+cell size may affect the time step and, consequently, the duration of the
+calculations. Therefore, it is recommended not to unnecessarily reduce the cell
+size.
 
+The SMODERP2D model is designed for catchment-scale applications and is not
+suitable for computing large continental-scale hydrological events. It is
+recommended for use in areas with a single outlet point and an area ranging
+from tens to tens of thousands of square meters.
 
+At its current state, the model does not allow water in the watercourse to
+overflow back to the surrounding land. However, the model can provide users
+with an estimation of how deep a watercourse must be to prevent overflow.
+
+## Data requirements
+The model operates with geographical data using common GIS software
+(Geographical Information System). Therefore, typical input data for the model
+are in the form of rasters and vectors. Rainfall data is provided as a plain
+text file.  Similarly, the model outputs are stored in open-source raster and
+vector formats, as well as plain text files.
+
+## Hardware requirements
+The model can run on standard laptops, PCs, or server hardware. However,
+workstations tend to expedite calculations due to their high-end CPUs. RAM and
+storage recommendations vary depending on the size of the modeled area and
+spatial resolution.