Groundwater and Agriculture: Meeting the Demands While Protecting Resources: Alphabetical Content Listing
Session 1: Agricultural Water Supply
Conjunctive Water Management in Nebraska: Recharging Aquifers through Excess Surface Water Diversions
Jessie Strom
Nebraska faces the challenge of allocating variable water supplies between multiple competing interests. In order to maximize beneficial water use and minimize negative impacts on streamflows and groundwater levels, conjunctive water management strategies are employed throughout the state to take advantage of the strong connection between surface water and groundwater resources. Nebraska is fortunate to have expansive aquifers adjacent to most of its streams and a significant network of unlined irrigation canal systems to use for conjunctive management. The aquifers serve as storage reservoirs for recharged water and provide a conveyance mechanism for its return to the stream. In the Upper Platte River Basin the Nebraska Department of Natural Resources, local natural resources districts, and irrigation districts, have cooperated to create successful outcomes through diversions into irrigation canals, recharge pits, and surface water reservoirs. This not only results in groundwater recharge, thus increasing water storage levels in the aquifer and groundwater discharge to streams, but also provides flood mitigation.
Drought Resiliency Solutions for Alluvial Wellfields
Nathan Holt
Shallow alluvial aquifers are particularly vulnerable to drought due to their dependency on recharge from surface water and precipitation. Northwest Iowa, a region with a multi-billion agribusiness industry, relies heavily on groundwater from alluvial aquifers, and saw this vulnerability firsthand. Iowa experienced a severe statewide drought starting in the fall of 2011 and continuing through most of 2012 and 2013. The drought put rural communities and agribusinesses at risk. One regional water supplier had to implement an emergency water plan. A temporary water-use permit was issued by the Iowa Department of Natural Resources to pump water from the Big Sioux River into a recharge basin to prevent the production wells from going dry. Public water utilities, like the one in northwest Iowa, are continuously looking for ways to increase their drought resiliency and manage water sustainability. One way to improve drought resiliency is to implement strategies that increase surface water (induced) recharge into the aquifer. The Iowa Geological Survey evaluated several drought strategies in Northwest Iowa, including recharge basins and rock riffles. The different strategies’ impact on groundwater quantity and quality will be presented. A framework for selecting a potential drought strategy for any given wellfield will also be discussed.
Managing Long-Term Groundwater Quality in the Food and Beverage Sector Using Managed Aquifer Recharge
Sean Cassidy
The management of a catchment scale groundwater resource is an ongoing challenge in the food and beverage sector. Water bottling and public water supply facilities once located in relatively low-density, pristine catchments are now facing challenges associated with urban sprawl, rising food demands, and ultimately water intensive industries, such as agriculture.
Catchment land use practices is a key consideration for any industry reliant on a sustainable groundwater resource. The ongoing management of groundwater storage, water quality and levels should be at the forefront of any food and beverage facility. Adequate monitoring of local and regional groundwater and surface water environments and an in-depth understanding of industries operating within the groundwater catchment is key to managing the ongoing operation of these facilities.
Rising nitrate concentrations in groundwater linked to nutrient leaching from farming is a growing concern in the United Kingdom. Water bottlers, reliant on access to a high quality resource are now facing increasing operating costs due to source contamination and treatment. Various water bottlers have taken to Managed Aquifer Recharge (MAR) as a tool to manage shallow groundwater contamination and reduce operating costs. The benefits of MAR are widespread and could become increasingly necessary in the future.
NGWA Best Suggested Practices for Managed Aquifer Recharge
William Alley, Ph.D.
Water supply shortages are occurring now and are expected to occur more widely in the future. Managed aquifer recharge (MAR) will become an increasingly important tool for mitigating the economic, environmental, and public health impacts of these shortages. MAR captures available water (during wet periods, during periods of low demand, or water that would be lost otherwise) and moves this water under controlled conditions into underground reservoirs. Properly sited, designed, constructed, operated, and maintained MAR projects are a key component for addressing the nation’s water supply challenges. This paper discusses NGWA’s Best Suggested Practices for Aquifer Storage and Recovery (ASR), which are intended to foster the conceptualization, planning, and implementation of an aquifer storage and recovery project and examples of current efforts to apply MAR to agricultural settings.
Session 2: Groundwater Availability and Quality
Data-Based Sustainable Agriculture: Small-Scale Irrigation Development in Africa
William Alley, Ph.D.
Warming temperatures, changes in precipitation patterns, and population growth are leading to increasing or new dependences of agriculture on groundwater. In Africa, less than 1% of agricultural land is currently irrigated with groundwater, however environmental, population, and economic pressures are motivating an increase in groundwater use. In light of unsustainable groundwater consumption in parts of the developed world, we aim to address the challenge of sustainable irrigation development across Africa. We present a remote sensing and field data-based irrigation decision support tool to reduce risk and improve yields for smallholder farmers within a changing climate. The tool will meet the needs of individual farmers as well as government or NGO organizations who are setting policies and targeting groundwater development efforts. Environmental and hydrogeologic data carry various degrees of uncertainty across the Continent, and there are inherent uncertainties in modeling crop yield response to changes in management; therefore, we aim to convey the uncertainty associated with each irrigation recommendation, allowing farmers to balance their personal tolerance for crop production uncertainty and financial risk. These results will have implications for smallholder farmer food and water security, and will help inform management decisions in a rapidly changing and resource-constrained world.
High Frequency Nitrate Concentrations Measured in Two Iowa Springs Fed by Intense Row Crop Agriculture
Keith Schilling
Nitratax sensors were deployed to measure high frequency nitrate concentrations discharging at two fish hatchery springs in northeast Iowa to assess groundwater vulnerabilities. At Big Spring in Clayton County, Ordovician-age carbonate rocks exhibit karst development and 10% of the watershed drains to sinkholes. Over a 2-year period, nitrate concentrations averaged 12.4 ± 0.94 mg/l and exhibited a pronounced decrease in concentration following runoff events. Near the Manchester hatchery in Delaware County, Silurian-age dolomite is overlain by variable sandy surficial materials. N sensor deployment revealed higher nitrate concentrations (averaging 17.4 ±1.9 mg/l), with concentrations increasing after rainfall periods before returning to high baseline values. The difference in nitrate concentration patterns observed at the two Iowa springs indicates differences in hydrologic pathways. While both springs are heavily impacted by agricultural-sourced nitrogen from row-crop dominated watersheds (>80%), decreases in nitrate at Big Spring are indicative of low N in runoff lost to sinkholes features diluting the groundwater baseflow signal. In contrast, much higher concentrations and increases in nitrate following wet periods at Manchester is indicative of systemic high nitrate levels throughout the aquifer system. Both spring areas will require consideration of their distinct nitrate delivery pathways to implement groundwater-based nutrient reduction strategies.
Iowa Experience With Agricultural Drainage Well Inspection, Testing, Permitting, and Closure
Michael K. Anderson, PE
The Iowa Department of Natural Resources (IDNR) adopted rules to minimize contamination potential of Agricultural Drainage Wells (ADWs). Iowa’s water rights law was modified to permit the "diversion" of surface water into an aquifer, which precisely included ADWs. Agricultural drainage wells were constructed in Iowa in the early 1900s to provide outlets for surface runoff and tile drainage from cropland areas. Because ADWs discharge water directly to aquifers, they are routes for movement of contaminants. Cost-share funds allocated to close 400 of these wells on a priority basis. Alternative drainage outlets are developed to surface streams needed to replace these wells. Alternative drainage outlets are typically developed through formation of drainage districts. Environmental risk associated with ADWs in proximity to earthen waste storage units has been eliminated. About 155 were continued use permits. These permits were valid for ten years; most expired in 2009. For renewal, physical on-site inspections and water quality testing was required. Results from the on-going closure program and the re-inspection program have reduced the well number to 30. Legal and regulatory issues to reduce risks from ADWs, expanding discussion about lessening the nutrient loading to streams, since IA shifted discharge of pollutants from subsurface to surface.
Mississippi’s Approach to Address Declining Groundwater Levels
Kay Whittington, PE
Groundwater levels in the aquifer used for agriculture and wildlife in the Mississippi Delta are declining as irrigation demands have increased. By law, the Mississippi Department of Environmental Quality (MDEQ) is charged with conserving, managing, developing, and protecting the state’s water resources. MDEQ is working with those in the Delta through the Delta Sustainable Water Resources Task Force. A Voluntary Metering Program is being implemented to annually collect metered water use information. Water use efficiency practices proven to save water, time, and money are being required through water use permits. Progress is being made in improving our information and through the implementation of conservation measures while all options continue to be investigated using a regional groundwater availability model developed in cooperation with the United States Geological Survey (USGS).
Multiple Isotopes Reveal Spatial Complexities of Baseflow Sources in the Wabash River Watershed in Indiana and Ohio
Marty Frisbee
Identifying the sources of water which contribute to baseflow in agriculturally-fragmented watersheds is critical to understanding spatial and temporal trends in solute and nutrient loading. Shallow phreatic aquifers and tile-drain waters commonly have elevated nutrient concentrations, but modern residence times. These waters can mask the geochemical signature and residence time of older sources of groundwater making it difficult to determine how they impact baseflow processes. This problem is addressed by sampling for general chemistry, 36Cl, and 87Sr/86Sr at sites located longitudinally down the Wabash River. Many of the river samples collected in October and November of 2015, after widespread flooding during the summer of 2015, track the 36Cl/Cl ratios of precipitation (40 to 80 x 10-15). However, three sites had relatively low 36Cl/Cl ratios and high Cl-, SO42-, Sr2+ and Cl-/Br- ratios indicative of discharge from a deep regional aquifer. Three sites had relatively high 36Cl ratios and low Cl-, SO42-, Sr2+ and Cl-/Br- ratios indicative of mixing between recent runoff and discharge of bomb-pulse aged groundwater. Altogether, these data show the utility of incorporating cosmogenic isotopes in studies of agricultural watersheds where they provide a unique way to identify both recent, bomb-pulse, and very old recharge in agriculturally-fragmented watersheds.
Restoring Stream Flow and Reducing Groundwater Use Through Conservation Irrigation
Julie Blackburn
Irrigation using groundwater exceeds or is approaching sustainable thresholds in many areas across the United States. Little Rock Creek is one of four DNR groundwater management areas in the state. This groundwater fed, cold-water, trout stream is impaired due to a lack of coldwater fish assemblage, low dissolved oxygen, and excess nitrogen. Restoration efforts focus on reducing groundwater use to improve base flow conditions in the creek. Reducing groundwater use through conservation irrigation is the focus of this Environment and Natural Resource Trust Fund (ENRTF) project. Most conservation irrigation scheduling tools available are outdated and no longer effective in meeting resource management needs. This project consists of developing an open source, web-based, mobile irrigation scheduling application that also provides users with real-time information on stream conditions and regularly updated information on groundwater levels.
Technical Analyses that Inform Groundwater Policy Decisions in the Nebraska Panhandle
Thad Kuntz, PG
In the Nebraska Panhandle, two modeling efforts have been developed to provide decision support information, tools, and analyses of water resources policy decisions for the local Natural Resources Districts (NRD) and the State of Nebraska Department of Natural Resources. The NRDs are governmental entities with locally elected Board of Directors that are responsible for regulating and managing groundwater pumping over multiple counties.
The modeling efforts encompass nearly the entire Nebraska Panhandle between the Wyoming, Colorado, and South Dakota borders. The area includes three rivers, multiple small tributaries, and the High Plains Aquifer that locally consists of alluvial, aeolian (Nebraska Sandhills), Ogallala, and Arikaree aquifers. The Nebraska Panhandle is primarily rural and agricultural based with irrigation the primary water use. Numerous technical and modeling analyses that have been completed and include streamflow depletion, aquifer longevity, drought planning, and accretion analyses. Ultimately, the results of these analyses are used to help educate and inform the public, open up dialog on groundwater management, and provide the NRD Boards with information to aid their policy decisions to determine future groundwater pumping allocations. A review of these analyses provides an insight into the effort these NRDs take to understand their groundwater policy and management.