kelleythompson
commented
5 months ago The StateCU fortran code was modified to consider direct use of surface water use in gw-sprinklers using a file that can specify the acre-feet of surface water used or the acres of gw-sprinklers that are using surface water. The direct surface water use data are supplied in a new “.swd” file that is defined in the model “.rcu” file. In the .swd file, rows of data are oriented as year, type, structure, and value. Entries with a type of “1” indicate that an annual value in acre-feet is being supplied, while a type “2” indicates that a value in acres is being supplied. The code distributes annual type 1 values to a monthly distribution based on the monthly distribution of surface water diversions at the river headgate. The monthly value acre-foot value is subtracted from the monthly managed recharge amount and added to the surface water applied to the gw-sprinkler acreage for the structure. With type 2, the monthly farm surface water diversion is multiplied by the ratio of the acre value to the total structure area to determine a surface water amount, and this amount is then subtracted from the monthly managed recharge amount and added to the surface water applied to the gw-sprinkler acreage for the structure.
The revised code was compiled in gfortran as version 14.01.00. That executable and a .swd file that utilizes both type 1 and type 2 entries are being used successfully for the current phase 7 RGDSS StateCU model. For an example, an example .swd file is attached. However, note that a .txt file extension was added for upload to github, for use in StateCU this .txt would be removed. Also note that although this draft file references the RGDSS model, the file itself is provided purely for example purposes and should not be considered usable or relevant within the actual RGDSS model.
Some ditches in the Rio Grande Basin have historically recharged diverted surface water while primarily using wells to irrigate ditch lands through sprinkler irrigation systems. Many of these ditches have obtained recharge decrees from water court to confirm this practice.
Under typical (gmode=2) settings, the StateCU model assumes that surface water is used first for both flood and sprinkler irrigation, and then available wells can be pumped to satisfy any remaining crop demands. However, in the Rio Grande Decision Support System (RGDSS) StateCU model, a “gmode=3” setting is specified for the ditches that recharge surface water. The StateCU model uses available surface water to supply flood irrigated lands and lands without any groundwater supplies but assumes that pumping is used to satisfy demands for sprinkler irrigated lands with groundwater supplies (“gw-sprinklers”). StateCU first prorates the proportion of surface water going to different field types using the acres of sw-flood, sw-sprinkler, gw-flood, and gw-sprinkler irrigated parcels (“sw” means surface water only while “gw” means the parcel is supplied by both surface water and one or more wells). So, for the structures with a gmode setting of 3, the water prorated to gw-sprinkler parcels is not used to supply consumption, but instead is considered “managed” recharge.
However, in these ditches, some surface water has been directly used in sprinklers. Measurements of direct use of surface water in sprinklers have been maintained since 2012 by Subdistrct No. 1 for fee purposes and it is also known that a group of sprinklers in one of the ditches with recharge decrees but outside of Subdistrict 1 have also been using surface water directly. Therefore, a capability in StateCU is needed, for a structure using the gmode=3 setting, to be able to supply either a certain number of acres of gw-sprinklers were using surface water directly or a measured amount surface water was being used in gw-sprinklers and to have the associated amount of surface water be supplied to the gw-sprinkler acres for consumption prior to use of supplemental well water.