NU Water-Related Research in Hamilton County

It has been established with a degree of confidence that the temperature of the earth’s atmosphere has increased by about 0.3 to 0.6 degrees C in the late 19th century (IPCC, 1997). Global warming can have substantial impact on agricultural production, water resources, and their interactions, by influencing microclimatic variables that drive plant physiological functions, such as surface air temperature, solar radiation, humidity, wind speed, rainfall frequency and amount, as well as hydrological balances, including evapotranspiration. Knowledge and analyses of long-term historical trends in agro-meteorological and hydrological parameters can aid in water resources design, planning, and man-agement. Historical trends in these variables can also help to relate agro-ecosystem production to climate change. We assessed the long-term trends in climatic variables. We quantified reference evapo-transpiration from solar and net radiation, vapor pressure deficit, wind speed, relative humidity, and air temperature from 1893 to 2008 using measured and estimated climatic data. Both alfalfa-reference and grass-reference evapotranspiration values were computed on a daily time step. We present historical trends in air temperature, relative humidity, preci-pitation, solar radiation, and evapotranspiration from 116 years of climatic observations and modeling results in the Central Platte Valley, Nebraska.

Conclusions from this project are:

• Missing long-term climatic variables from 1893 to 1986 were reliably estimated for reference ET calculations.
• Annual total rainfall amount showed an increasing trend over 116 years.
• Both grass and alfalfa-reference ET fluctuated from year to year, but slightly decreased over the years.
• Solar radiation slightly decreased due to increased rainfall/cloud cover.
• Average vapour pressure deficit (VPD) did not change considerably.
• Aridity index trend indicates a general tendency for Central City, NE area to shift toward more humid conditions, more so in the last 10 years.

Ferguson is doing several projects with sites in Merrick and Hamilton counties focused on managing nitrogen applications to both benefit the crop and protect water quality.

• The Impact of Controlled Release Urea Formulation on Nitrate Leaching Below the Root Zone of Irrigated Corn - Merrick County. This study is measuring nitrate leaching throughout the growing season on a coarse-textured soil planted to irrigated corn. Treatments include different nitrogen fertilizer sources and rates.
• Relay Cropping Effects on Nitrate Accumulation in the Root Zone - Merrick County. This study evaluates the cumulative effect of the seed corn/winter wheat/relay-cropped soybean on nitrate accumulation in the root zone over the two year cropping system cycle.
• In-Season Nitrogen Management Using Active Crop Canopy Sensors - Hamilton and Merrick counties. This series of studies on multiple crops (winter wheat, commercial corn, seed corn) at multiple sites investigates the use of active crop canopy sensors to control nitrogen fertilizer application during the growing season, using the crop to detect soil N supply rather than predicting soil N supply through soil sampling.
• The Use of Polymers to Inhibit Nitrate Movement Below the Root Zone of Irrigated Corn - Merrick County. This study investigates the potential of various soil-applied polymers to retain nitrate in the root zone, preventing it from leaching into the vadose zone and eventually groundwater.

The hydrologic properties of channel sediments have an important role in controlling hydrologic process in streams. This study focused on the water exchange between a stream and an aquifer induced by groundwater withdrawal, with the purpose of investigating the interbedded feature of channel sediments and to evaluate its effects on the calculation of streamflow depletion. Field work was conducted at nine study sites between Kearney and Columbus during the summers of 2005 and 2006. Direct-push techniques were used to produce electrical conductivity logs and to collect sediment cores. Permeameter tests were conducted on the sediment cores. Stream-aquifer simulation models were used to evaluate streamflow depletion for various types of channel sediments.

Sediment core samples were categorized into four groups:

• sand and gravel,
• sand and gravel with interbedded silt and clay layers,
• fine sand with silt or clay layers, and
• silt and clay with some sand and gravel.

In general coarse sediments occur in the western part of the study area, and the amount of fine sand, silt and clay increases eastward along the river. However, the sediments in the top two meters are about the same for all the sites, consisting mainly of sand and gravel.

Application of two-step approach of evapotranspiration (ET) crop coefficients (Kc) to approximate a very complex process of actual evapotranspiration (ETa) for field crops has been practiced by water management community. However, the use of Kc, and in particular the concept of growing degree days (GDD) to estimate Kc, have not been sufficiently studied for estimation of evaporative losses from riparian vegetation. Our study is one of the first to develop evapotranspiration crop coefficient (KcET) curves for mixed riparian vegetation and transpiration (TRP) crop coefficients (KcTRP) for individual riparian species as a function GDD through extensive field campaigns conducted in 2009 and 2010 in the Platte River Basin in central Nebraska, USA.

Nebraska’s native prairies are a valued resource and under constant anthropogenic demand and degradation. By engaging land owners in voluntary programs, the Platte River Habitat Partnership aims to restore and enhance this important natural resource. In this project, the Public Policy Center conducted a survey to assess land owners’ perceptions of the Platte River Habitat Partnership to help direct the Partnership’s second phase. Specifically, land owners who live in the region covered by the Partnership but did not participate, and those that did participate in the Partnership were surveyed in order to answer four key questions: 1. How knowledgeable are these land owners about the Partnership? 2. What is the nature of these land owners’ interactions with the Partnership? 3. How is the Partnership itself generally perceived by these land owners? 4. What would encourage land owners who had not participated in the Partnership to participate?

The goal of this project is to enable onsite wastewater treatment system professionals to apply science-based onsite wastewater design, installation, and maintenance practices and thereby protect water resources and human health. As of December 31, 2005, onsite professionals must pass exams to be certified pumpers, installers, and/or inspectors in the state of Nebraska. In-depth curriculum for Nebraska onsite wastewater system installers, inspectors and pumpers was developed to address this issue. The curriculum helps individuals prepare for exams, as well as help professionals apply science-based practices to protect water resources.

During 2005 and 2006, UNL Extension had 733 educational training contacts. Knowledge and competency was demonstrated by 86 percent passing their exam(s). Results from a follow-up survey of 460 of those who had attended training indicated pumpers (90%), installers (99%) and inspectors (100%) increased knowledge. Pumpers (76%), installers (71%), and inspectors (90%) reported they had made practices changes which would result in water quality and human health being better protected.

Certification training continues on an annual basis and new curriculum is being developed for advanced alternative treatment systems. These systems can achieve greater water quality protection in vulnerable areas including those with high groundwater levels and/or sandy soils. Merrick, Hall, and Hamilton Counties have geographic areas of high risk from traditional onsite wastewater treatment systems due to these factors. Alternative systems could greatly reduce the risk of water quality degradation from nitrate and other contaminants in these areas.

Educational materials have also been developed and delivered for homeowners with onsite systems. The goal is to empower rural homeowners to protect water resources and human health through application of science-based onsite system maintenance and operation practices. Training was delivered in Grand Island and to 50 residents with onsite systems at Turtle Beach near Central City.

When new Environmental Protection Agency Safe Drinking Water Act standards for arsenic and uranium were enacted, 82 Nebraska public water supplies had arsenic concentrations above the maximum level allowed and 20 had uranium above the standard, including public water supplies in Hamilton, Hall, and Merrick counties. Since arsenic and uranium are naturally occurring in rocks and soil, private water supplies in these geographic areas could also be at risk of having elevated concentrations, possibly putting families at risk from chronic exposure.

A UNL Extension team with a drinking water focus developed and delivered training to UNL Extension faculty/staff in targeted areas at high risk for naturally occurring arsenic and/or uranium. Twelve training sessions were delivered in 2005 including training in Merrick and Hall Counties. Thirty-nine extension personnel with a focus or job description other than drinking water were trained, including 3 in Hall County and 3 in Merrick County. Participants increased their knowledge of the topic in order to work better with owners of private drinking-water wells in the high risk areas. Of those returning an evaluation, 92% strongly agreed or agreed their knowledge increased in regard to arsenic and uranium occurrence, risk, testing, and treatment. These faculty and staff have gone on to provide information and education at the local level to private well owners.

Training on arsenic and uranium in drinking water was delivered at the Nebraska Well Drillers Winter Short Course in 2006 and information on arsenic in drinking water was presented in 2007. Nearly 300 water well professionals attended in 2006 and approximately 250 attended in 2007. Seven percent of 2006 participants evaluating the program indicated the arsenic and uranium program was the best topic during the event, and 19% indicated they were interested in learning more about the topic. Participants indicated they would use the information gained to "spread knowledge on arsenic and uranium to pivot system owners," "educate/inform constituents, customers," "expand markets in arsenic and uranium testing," or "provide safer water."

UNL Extension also delivered training on arsenic and uranium in drinking water at a Professionals Seminar in 2006. Thirty-eight professionals attended. Several professionals involved stated that the focused three-hour presentation gave them an excellent overview of the pertinent design issues which communities and engineers should consider when selecting a method of dealing with high arsenic and uranium levels. They especially appreciated the mix of technical presentations with a panel discussion by community members, regulators, and local engineers.

The Rainwater Basin is one of the most endangered wetland ecosystems in North America. This ecosystem is critical to many species including migratory waterfowl. Land use and runnoff from agriculture and cattle confinement operations are likely to be reducing the basin's health and diversity, however little information exists concerning macroinvertebrates. Twenty-two locations were assessed for water quality parameters, vegetation composition, and macroinvertebrates identified to genus. Samples were collected biweekly starting in April through July for three years. Macroinvertebrate diversity was impacted in areas with little buffer although the effects were not pronounced. Institution of a more effective vegetative buffers strip may reverse this trend to improve ecosystem quality and provide for invertebrate resources for migratory birds.

Click here to see a poster about this research