OWRB implemented the Stream Water Allocation Modeling Program in 2009 to support the appropriation, allocation, distribution, and management of stream water in the state. The program is a pioneer statewide initiative in the United States for the assessment of both water availability and reliability as well as a supporting tool for the adjudication and effective management of water rights in Oklahoma. Models are being used by OWRB staff to:
- Assess water availability and flow reliability at any location in the basin on an annual and seasonal basis. This information assists current permit holders to maximize the productive use of water and make decisions about infrastructure, types of crops, schedules of use, etc.
- Estimate the amount of unappropriated water in the system, i.e. the amount of water remaining in a stream after taking into account complete satisfaction of all existing water rights valued at their full authorized amounts and conditions. The OWRB uses these estimates to evaluate new water-right applications.
- Perform drought analyses to determine areas in the basin and water rights that are sensitive to water shortages due to low-flow conditions or interference of water rights. The information is used by the permitting staff to contact users and manage the resource (voluntary or imposed reductions or changes in schedules).
- Evaluate water policy decisions, including allocation of water, inter/intra basin transfers, interstate stream compacts, climate change, etc. These analyses anticipate the effect of specific management decision and evaluate a range of policy options in advance of their implementation.
What are allocation models?
Allocation models are computer applications that contain data about the river-basin hydrology and active water rights in the system (curently over 60 years of data), capturing the essential statistical characteristics of the hydrologic system and accounting for the probable range of its future hydrology. The models are constructed using a network-flow algorithm in Microsoft ExcelŽ called the Central Resource Allocation Model (CRAM) which simulates management of the water resources under a priority-based water allocation system. Water is distributed in the system on a monthly basis and demands or "water rights" are supplied based upon a selected management scenario. Results from a simulation include estimates of water availability (before and after appropriation), flow and content at reservoirs, amount and frequency of water shortages, and interference of water rights. The OWRB has developed software applications to effectively display the results from the models through statistics, graphs, tables, and maps that show the detail of the spatial and temporal resolution of the model.
The OWRB has completed in-house allocation models for ten (10) stream systems in the state, including the Canadian River. Five basins were modeled by a contractor for the Arbuckle-Simpson Hydrologic Study and the 2012 Oklahoma Comprehensive Water Plan (OCWP). Future work on the Verdigris River, North Fork Red River, and North Canadian River systems will be developed in 2013. Estimates of water availability from the allocation models have been included in recent hydrologic investigations for the following stream systems: Upper Canadian (see report), Kiamichi, Cache & Beaver Creek, Middle Canadian, Lower Canadian & Little River.
Fig. 1 Stream water allocation models completed for stream systems in Oklahoma. View high resolution version...