Div1_Irrig_2020

In 2013, groundwater attributes were assessed and reassigned according to water court decree and/or well permit information. As a result, GW_Class was reset to follow a new criteria. 1 = Field Verified well to parcel relationship, 2 = Decree or Permitted specified well to parcel relationship, 3 = Interpolated well to parcel relationship.

In 2010, the SPDSS moved to a new process for delineating and crop typing irrigated parcels. Data used in this analysis include...most recent NAIP aerial photography, 24k DRG layer, National Agricultural Statistics Service Cropland Data Layer and Landsat Satellite Imagery from growing season processed into Max NDVI layer. The process begins with a section by section review of the snapshot parcel layer, NASS CDL for the crop year and the most recent aerial photography. The goal is to identify multiple crops within a snapshot field boundary and split the field to according to the crop splits in the NASS CDL data. Only clear splits should be made. Speckled fields with multiple crop types should be left whole for later analysis. Once this process is finished, values from the NASS CDL and the NDVI scenes need to be extracted to the snapshot layer. This process is done with EDRAS. ERDAS is used to pull over NASS CDL values, as well as, temporal NDVI values within field boundaries. NASS CDL values are used for assigning crop types to the master irrigated parcel file. The first step in this process is to identify fallow parcels and code them as ‘NO_CROP’ in the ‘CROP_TYPE’ field. Any parcel with all NDVI scene values below 130 should be coded as ‘NO_CROP’. For example, in the above table, the first record would fall into this category. Conversely, any parcel with a NDVI value above 150 for any month should be considered irrigated. The next step in the analysis process involves coding crops that are considered irrigated, have a ‘Maj_Frac’ value >= 70% and are an index crop. In the above table, master ids 1797, 1798 and 1800 would fall into this category. Oats, barley and potatoes are all considered index crops and all three have ‘Maj_Frac’ values above 70%. Also, each one has at least one month with an NDVI value above 150. These crops can be coded into the ‘CROP_TYPE’ field with barley and potatoes being directly attributed and oats being coded as ‘SMALL_GRAINS’. This process is repeated for all index crops with some crops being coded as CDSS values as opposed to their actual value. This mostly happens with small grains, such as, oats, millet, and rye. Once this process is finished and the high probability index crops have been coded, each index crop needs to be examined and coded. Start with analyzing each individual index crop by adjusting the selection to include those crops with ‘Maj_Frac’ of 60-70% and reducing the ‘Maj_Frac’ value down by increments of 10% until reaching ‘Maj_Frac’ >= 50%. This process can be done by analyzing groups of parcels visually and making determinations on crop type. Parcels with a ‘Maj_Frac’ below 50% need to be examined individually, taking into account the NDVI values over the growing season and potential farming practices (i.e. Alfalfa cuttings). The result is a crop typed irrigated lands coverage.