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South Platte Mapping and Analysis Program Completes Current Phase
<br />and Begins New Improvement Phase
<br />by Luis A. Garcia and David Patterson
<br />Colorado State University
<br />The science behind conjunctive management of ground
<br />and surface water has received renewed interest in recent
<br />years as court approved augmentation plans must be in place
<br />to insure that well pumping does not damage senior water
<br />rights. Development of augmentation plans requires an
<br />ability to estimate the impact well pumping has on stream
<br />flows over time. Such relationships can be complex, requir-
<br />ing models and extensive data to develop estimates that are
<br />widely accepted by all parties involved.
<br />The South Platte Mapping and Analysis Program's (SP-
<br />MAP) primary function is to accurately determine the timing
<br />and amounts of groundwater withdrawals used for irrigated
<br />agriculture. Accurate accounting of groundwater withdrawals
<br />allows water managers to meet the challenges of new court
<br />decrees and legislation related to the South Platte.
<br />The SPMAP project began in 1995 with the formation of
<br />an advisory group comprised of representatives from the
<br />Northern Colorado Water Conservancy District (NCWCD),
<br />the South Platte Lower River Group, Inc. (SPLRG), the
<br />Colorado State Engineers Office (SEO), Groundwater Ap-
<br />propriators of the South Platte (GASP), the Central Colorado
<br />Water Conservancy District (CCWCD), the Lower South
<br />Platte Water Conservancy District (LSPWCD), the City of
<br />Greeley, and the City of Fort Collins. Over the years, some of
<br />the participants have changed, but the core group of advisors
<br />has continued to meet regularly. The tools developed on the
<br />advice of these meetings are increasingly being used through-
<br />out the state.
<br />SPMAP, as a set of computer tools, has been developed by
<br />the Integrated Decision Support (IDS) Group at Colorado
<br />State University (www.ids.colostate.edu). SPMAP matches
<br />data acquisition, system design, modeling, and user interfaces
<br />with the needs of area water managers. SPMAP software
<br />consists of three main components including Geographic
<br />Information System data and analysis tools (SPGIS), a con-
<br />sumptive use model (IDSCU), and stream depletion model
<br />(IDS AWAS) which calculate the time elapsed between when
<br />a groundwater recharge or withdrawal event occurs and when
<br />an accretion or depletion happens in the river.
<br />Funding for this project was provided by the water organiza-
<br />tions participating in the advisory committee listed above, the
<br />Colorado Water Resources Research Institute, Colorado State
<br />University Cooperative Extension, Colorado State Experi-
<br />ment Station and the US Bureau of Reclamation.
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<br />In order to manage the conjunctive use of ground and surface
<br />water resources, tools need to be developed to evaluate four
<br />issues: 1) water demands, 2) water supplies, 3) depletions of
<br />groundwater and resulting augmentation requirements, and
<br />4) impacts to rivers. Furthermore, managers require tools that
<br />can work with both large and small areas and over different
<br />time scales.
<br />Decision support systems, such as SPMAP, have been em-
<br />ployed in other Colorado river basins to model water supply,
<br />and the Lower South Platte River basin has been a testing
<br />ground for decision support systems since the early eight-
<br />ies. Due to the complex nature of the South Platte, computer
<br />tools promise significant benefits for improving water man-
<br />agement.
<br />Tools such as SPWRMS (South Platte Water Rights Man-
<br />agement System), SAMSON (Stream Aquifer Model for
<br />Management by Simulation and Optimization), and others
<br />have been evaluated and presented in a number of CWRRI
<br />publications (Raymond et al., 1996; McCarthy and Light,
<br />1995; Kuhnhardt and Fontane, 1995; Warner et al., 1994;
<br />and Klein, 1994). In addition to these efforts, the State of
<br />Colorado has begun to implement a decision support system
<br />for the entire South Platte River Basin (CWCB, 2000).
<br />The initial goal of the SPMPAP project was to identify gaps
<br />in water management tools available in the Lower South
<br />Platte River Basin and implement computer systems that
<br />could be incorporated into a future decision support frame-
<br />work. The goal of the continued project was to improve on
<br />the tools developed. A new user - centered approach to water
<br />research has been an essential part of the project. The ap-
<br />proach expressly elicits information from water managers to
<br />develop data acquisition, modeling, and user interfaces that
<br />meet managers' needs.
<br />SPMAP has been developed according to the following
<br />timeline:
<br />• 1995 -96 Project efforts focused on spatial data collection
<br />and evaluation. A GIS tool was developed as an extension
<br />to ArcView 3.0+ to provide users with the capability of
<br />viewing and using spatial data, such as themes for irrigated
<br />lands, well locations, stream depletion factors, hydrography,
<br />weather stations, county boundaries, roads, and cities.
<br />• 1997 -98 A Consumptive Use model called the South Platte
<br />Consumptive Use (SPCU) Model and an interface for a
<br />Stream Depletion Factor (SDF) model began development.
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