SPDSS_Task34-3_Phase 3_StreambedConductanceTesting

• Title: SPDSS Task 34.3 - Streambed Conductance Testing - Phase 3
• Description: The objective of this Task 34 is to collect data needed to quantify the groundwater flux across the streambed in the South Platte River and significant tributaries.
• Decision Support - Doc Type: Task Memorandum
• Date: 6/28/2007
• DSS Category: Groundwater
• DSS: South Platte
• Basin: South Platte
• Contract/PO #: C153953
• Grant Type: Non-Reimbursable
• Bill Number: SB01-157, HB02-1152, SB03-110, HB04-1221, SB05-084, HB06-1313, SB07-122
• Prepared By: CDM

SPDSS Phase 3 Task 34.3 Streambed Conductance
Technical Memorandum
FINAL
To: Pay Alvarado, CWCB
From: Camp Dresser & McKee Inc.
Jessica Poceta, Hanna Sloan, Andy Horn, Gordon McCurry, and Mike
Smith
Subject: SPDSS Groundwater Component, Phase 3, Task 34 Streambed
Conductance Testing
Date: June 9, 2006 (Minor revisions June 28, 2007)
Introduction
The groundwater component of Phase 3 of the South Platte Decision Support System
(SPDSS) includes compiling and evaluating available relevant data to support t11e
Decision Support System (DSS) for the South Platte River watershed and to add the
data to HydroBase, the State of Colorado's hydrological database. The SPDSS
groundwater study area is presented in Figure 1.
This task was undertaken for the Colorado Water Conservation Board (CWCB) and
Division of Water Resources (DWR), under Task 34 of Phase 3 of the SPDSS by Camp
Dresser & McKee Inc (CDM). Cooperation from many organizations, municipalities,
and individuals greatly assisted the SPDSS by allowing access to testing sites located
on private land and by providing data to the SPDSS. CDM and fl1e State express their
greatest appreciation to all of those who have cooperated with t11e SPDSS.
The objective of this Task 34 is:
1. Collect data needed to c~itir~ntify the groundz ater flint ae~~oss the Streambed in the Sol.{th
Platte River anc~ significant tributaries.
T11e groundwater flux across a Streambed, representing fl1e amount of water either
gained or lost by the stream, is an important concept when evaluating stream-aquifer
interactions, and is critical in numerical modeling of suc11 systems. One of the
parameters used in modeling of groundwater flux across a Streambed is the
streambed conductance term which is an input to the MODFLOW Streaniflow-
Routing Package (Prudic et al. 2004), anticipated to be used in groundwater modeling
of the South Platte alluvial aquifers plaiuled under Task 48. Streambed conductance
takes into account t11e Streambed hydraulic conductivity (K), thickness of Streambed
sediments, general Streambed geometry, and width and length of the stream channel
within a model cell.
Fnlal T~zsl: 3~TM 06-28-07.doc