Timothy Gates

1. Water Quality and Productivity Enhancement in an
Irrigated River Basin through Participatory
Conservation Planning and Analysis
Timothy K. Gates1, John W. Labadie1, Ryan T. Bailey1, Dana Hoag2,
Jim Valliant, Saman Tavakoli1, Faizal Rohmat1, Ravi Kumar1, Brent Heesemann1, Misti Sharp2, Chris Shultz1
1Department of Civil and Environmental Engineering, Colorado State University (CSU)
2Department of Agricultural and Resource Economics, CSU
October 2014 – September 2017
Objectives
RVL
V
B
The Lower Arkansas River Valley (LARV) in Colorado has a long
history of agricultural production; however, problems have
immerged related to long-term irrigation. Salinization and
waterlogging have become wide-spread throughout the valley,
diminishing crop yield. Additionally, selenium (Se) concentrations
in the river vastly exceed the current Colorado Department of
Public Health and Environment (CDPHE) chronic standard. This
project seeks to assess the effectiveness of conservation
measures (best management practices) that curtail these
problems, are realistic socio-economically, and comply with the
Arkansas River Compact through the refinement and application
of two regional-scale (~500 km2) stream-aquifer models and a
basin wide (~2000 km2) river network hydrologic model. A
stakeholder advisory group steers researchers in using data and
models to find practicable solutions for pilot implementation.
Problem
Research Objectives
1. Identify conservation practices and describe impact in
improving water quality (in regard to salinity, selenium, and
nutrients), boosting agricultural productivity, and saving
water in the irrigated stream-aquifer system.
2. Identify river-reservoir system operation strategies at the
basin-scale that permit implementation of conservation
practices in the LARV so as to comply with State water law
and the interstate Compact.
3. Measure economic standing of alternative conservation
practices and river-reservoir operation/flow augmentation
options.
4. Incorporate data and impacts of conservation practices and
river operation/flow augmentation options into a platform
that invites participation by interested stakeholders and
educates policy makers as to benefits of integrated basin-
wide water management.
Extension Objectives
1. Evaluate, through participation with water users and
agencies, the technical, socio-economic, and administrative
viability of alternative conservation practices and river-
reservoir operation/flow augmentation options and
determine a recommended set of best options.
2. Broaden the understanding of local water users in the
water quality and productivity implications resulting from
irrigation practices, reservoir operations, and compact
compliance issues.
Education Objectives
1. Improve education and involvement of water users,
agencies, and students in participatory identification,
evaluation, and administrative enablement of conservation
practices using data and models.
2. Provide active participation opportunities for graduate and
undergraduate students to engage in the proposed
research, education, and extension activities.
3. Develop and disseminate the results of this research as
undergraduate and graduate level course material related
to conservation of water resources at the river basin scale.
Task 2. Regional-Scale Analysis of Alternative
Conservation Practices.
Salinity
Selenium and Nitrate
Task 3. Basin-scale Analysis of Flow Augmentation and
River-Reservoir Operations.
Task 4. Economic Analysis of Alternative Improvements.
Task 5. Collaborative Examination and Assessment of
Improvement Alternatives.
Task 6. Recommended Ranking of Improvement
Alternatives.
Task 7. Dissemination of Findings.
Downstream Study Region (DSR)
Upstream Study Region (USR)
Map of Colorado’s Lower Arkansas River Valley and the upstream and
downstream regions, the location of the two regional models.
Aerial view of the Lower
Arkansas River and irrigated
valley between La Junta and
Las Animas, Colorado.
Methods
Task 1. Formation and Preliminary Planning with
Stakeholder Advisory Group.
An Arkansas River Management Action Committee
(ARMAC) has been formed, composed of 12 LARV farmers, a
farm management consultant, and 9 representatives from key
State and Local water management agencies. The purpose is
to make recommendations on behalf of the LARV for pilot
testing of land and water management actions that will help
improve water quality in the river, the groundwater aquifer, and
soils, while increasing profitability and sustainability of irrigated
agriculture. This will involve evaluation of the technical,
socioeconomic, and administrative viability of alternative
management actions with the assistance of the CSU team.
Input Data
• Soil & landscape
properties
• Aquifer properties
• Crop properties
• Canal and irrigation
rates & concentrations
• Climatic data
MODFLOW-UZF
Sat-unsat flow model
UZF-RT3D
Sat-unsat transport model
• Advection
• Dispersion
• Kinetic Reactions
• Plant uptake
• Auto-and hetero-
trophic redox reactions
Equilibrium Chemical
Reaction Model
- Precipitation & Dissolution
- Ion Exchange
- Complexation
- pH, temp effects
Predicted Variables
- Sat-unsat water content
- Soil and aquifer salt
concentration
- Relative crop yield
- Salt load to river
The committee met in March and
June 2015 and plans to meet
quarterly throughout the life of
the project.
A survey of LARV stakeholders
has been developed to
determine baseline knowledge,
attitudes and practices related to
salinity, Se, and nutrient
pollution. Will repeat at project
end and compare to determine
project impacts.
ARMAC
Propose Solutions
Request Research
Review Research
Discuss/Debate Implications
Develop Action Plan
Adopt Best Solution
CSU
Collect Data
Build Models
Evaluate Solutions
Evaluate Impacts
Present to ARMAC
Revise and Repeat
0
10000
20000
30000
40000
50000
60000
0 5 10 15 20 25 30 35 40
Se(kg)
Time (years)
Cumulative mass flux of dissolved Se in River
for baseline and reduced fertilizer scenarios in the USR
Baseline
RF 10%
RF 20%
RF 30%
Regional Salt Model
Best management practices (BMPs) being considered
Reduced fertilizer application
Reduced irrigation
Land fallowing
Reduced canal sealing
Enhanced riparian buffer zones
Best management practices (BMPs) being considered
Reduced fertilizer application
Reduced irrigation
Land fallowing
Reduced canal sealing
Enhanced riparian buffer zones
Salts, NO3,SeO4
S
ET
Upflux
Irrigation
Seepage
Se
NO3
Salts, NO3,
SeO4
Geo-referenced
display and
interactive
scenario manager
Administrative
and surface
water network
modeling
Surface water –
Groundwater
model coupling
Groundwater
model
Spatiotemporal
Database
 NHD Plus database
 CDWR water rights
 USGS, NWS, EPA, NRCS
 CSU field data
Scenario Manager
 Historical baseline analysis
 BMP scenario analysis
Interactive basin-wide
management model
GIS
 Geo-referenced map display
 Feature selection tool
GeoMODSIM
 Geo-referenced surface water modeling
 Accounts for water rights, storage accounts,
exchanges, reservoir operations, and Arkansas
River Compact
MATLAB-ANN
 Stream-aquifer interaction
 Input: GIS-processed explanatory variables
 Output: MODFLOW-UZF return flow predictions
MODFLOW-UZF
 Regional scale 3D numerical groundwater model
 Developed for large part of the Lower Arkansas
River Basin
Core of the basin-wide modeling is the
coupling of the geo-referenced surface
water model (GeoMODSIM) and the
groundwater model (MODFLOW-UZF)
using Artificial Neural Network (ANN).
ANN is a learning model used to
approximate functions that can depend
on a large number of inputs. In this
case, ANN used to approximate
MODFLOW-UZF return flow using GIS-
processed explanatory variables, (e.g.,
river flow, canal diversion, pumping,
crop distribution).
GeoMODSIM models surface water
network and administrative aspects of
the network flow, including water rights,
winter water storage program, and
Arkansas River Compact.
BMP scenarios to be simulated in the
ArkGeoDSS to evaluate basin-wide
system response, alongside the
compliance with Colorado Water Law
and the Arkansas River Compact.
ArkGeoDSS
SeO4
SO4
Water Table
Irrigation
Water
Salts,
NO3,SeO4
Fertilizer
NH4
Salts,
NO3,SeO4
Root
Processes
Crop Yield Response
Model
Modeled baseline selenate
concentration in groundwater in
DSR.
Modeled reduction in selenate
concentration in groundwater in DSR from
38-yr implementation of BMP with reduced
fertilizer, reduced irrigation, land fallowing,
and reduced canal concentration.
Reduction in Se loading to Arkansas
River under different BMPs in the
USR
Reduction in NO3-N loading to
Arkansas River under different
BMPs in the USR
Preliminary indication of
improved total dissolved
solids concentration at the
Colorado-Kansas border with
selected BMPs, in compliance
with the Arkansas River
Compact.
-$140.00
-$120.00
-$100.00
-$80.00
-$60.00
-$40.00
-$20.00
$0.00
$20.00
-10 0 10 20 30 40 50
Cost,Millionsof$
Selenium Mass Reduction, %
Reduced Fertilizer
(RF)
Canal Sealing (CS)
Reduced Irrigation (RI)
Leasing Fallowing (LF)
Combination: LF, CS,
RF
Combination: RI, CS,
RF
Conceptual trade-off curves for Se
reduction BMPs.
Preliminary trade-off between cost and Se
reduction for selected BMPs.
Preliminary studies indicate pollutant reduction can be cost-effective, with combined
BMPs dominating outcomes . However, there is not continuity in trade-offs between
costs and pollution control when water institutions inordinately constrain decision makers
and when BMPs interact with one another.