Water Resources Engineering
Western
Water Consulting, Inc.
Water
Resources Engineering
[Home] [Water Resources Information] [Interesting Links] [Search Sites]
River
System and Water Rights Operations Modeling
Colorado River Decision Support System (CRDSS)
To facilitate informed decision making related to management of the water resources of the Colorado River, the State of Colorado through the Department of Natural Resources developed the Colorado River Decision Support System. The Colorado River Decision Support System is a combination of inter-connected computer models, databases and utility programs. Central to the CRDSS are databases containing historical information on streamflow, climate, water uses, and the tabulation of water rights. Decision makers use this computer based system to evaluate and simulate water resource issues including the following:
As a member of the consulting team selected to design and implement the CRDSS, assistance and guidance were provided in the development of the Water Resources Planning Model (WRPM). The WRPM is a network allocation model in which major stream features such as gaging stations, reservoirs, diversion structures, et cetera, are represented as nodes in the simulated river network. Water rights within the river basin (direct flow, storage, instream rights, exchanges and operational rules) are represented at nodes in the network. The WRPM allocates water to a node based on an assigned priority sequence.
Separate WRPMs were developed for each of the five principal drainage basins on Colorado's western slope (Yampa, White, Gunnison, San Juan/San Miguel and Colorado main stem). The consulting team was responsible for the analysis of the direct flow, storage, and instream flow water rights that were included in the WRPM. This work included the identification of key diversion/storage structures in each basin, assignment of those structures to nodes in the network model and determination of tributary areas at the major network nodes necessary to compute "base flows". Through interviews with the respective Division Engineers and water users, assistance and guidance were provided to establish the simulation of the operational rules for the major reservoirs (including Federal storage/irrigation projects). This work included stage-capacity-surface area relationships for reservoirs, criteria for project storage and releases, flood operations, user sub-accounts within the reservoir and decision criteria related to the interaction with direct flow rights supported by the reservoirs.
The consulting team analyzed the timing of surface and groundwater return flows from irrigation. Inclusion of these return flows is necessary in order to achieve a water balance in the river network model. The locations of return flows for the modeled structures were determined using aerial photographs and maps of the irrigated acreage prepared by the Division of Water Resources and the U.S. Bureau of Reclamation.
To help evaluate water projects and their potential impacts on a river sytem, daily surface streamflow models have been developed along major river systems within Colorado:
These river models are based on historic daily streamflow data, water calls, and ditch diversion records. Inflow from ungaged tributaries is estimated using engineering hydrology methods based on drainage basin size, hydrogeologic characteristics, historic precipitation, and runoff from similar nearby drainage basins. Daily river gains and losses are estimated using measured daily flow values at U.S. Geological Survey stream gages within the modeled river reach. The calculated gains and/or losses are spatially distributed to specific locations along the river based on analyses in which the probable sources of inflows and outflows are identified. These analyses consider the location of irrigated lands contributing irrigation return flows, as well as the locations of gaged and ungaged discharges of municipal wastewater. The river models use the calculated river gains and losses, the historic stream flows and the historic diversions by ditches to compute the daily flows at any location throughout the modeled river reach. The calculated minimum flow at any location within the exchange reach defines the "exchange potential" for that day.
The river model developed for the Clear Creek basin has been adopted by industrial and municipal water users as a tool for administration of the entity's water rights. Additionally, the daily streamflow models have been used to estimate the biologically based 1E3 and 30E3 design low flows which dictate wastewater treatment requirements.
[Home] [Water Resources Information] [Interesting Links] [Search Sites]
