Kristoph-Dietrich Kinzli

Comparison of Laboratory and Field Calibration of a Soil-Moisture Capacitance Probe for Various Soils

AbstractThroughout the American west, irrigated agriculture has been targeted to increase water-use efficiency because of increased urban demands. Soil-moisture sensors offer a method to achieve efficiency improvements, but have found limited use primarily because of high cost and lack of soil-specific calibration equations. In this paper, the Decagon EC-20 soil-moisture sensor (a low-cost capacitance sensor) has been examined and a unique laboratory-calibration method has been developed. Field-and laboratory-calibration equations were developed for six soil types (sand, sandy loam, silt loam, loam, clay loam, and clay) in the Middle Rio Grande Valley for alfalfa and grass hay fields. The average absolute error in volumetric water content for field calibration was 0.430  m3/m3, and 0.012  m3/m3 for the laboratory calibration. The factory-calibration equation for the EC-20 was also evaluated and found to yield an average absolute error of 0.049  m3/m3. In this study, it was found that the EC-20 is a reliab...

Decision support systems for efficient irrigated agriculture

Water is the lifeblood of the American West and the foundation of its economy, but it remains its scarcest resource. The explosive population growth in western urban areas, the emerging need for water for environmental and recreational uses, and the national importance of the domestic food production from western farms are driving major conflicts between these competing water uses (US Department of Interior, 2003). Irrigated agriculture in particular is by far the largest water user – 80% countrywide and 90% in the Western U.S – and since it is perceived to be a comparatively inefficient user, it is frequently asked to decrease its water consumption. Irrigated agriculture in the Middle Rio Grande diverts large quantities of river water, which is believed to leave insufficient water to meet other societal needs such as urban and wildlife requirements. This paper will present our research on options to make irrigation system operations more efficient. Most irrigation systems can meet their users’ needs with decreased river diversions by adopting operational procedures, which are based on real-time knowledge of available water supplies and crop water requirements. The paper will describe our on-going research in the Middle Rio Grande Valley, to develop a Decision-Support System (DSS) that can assist water managers to closely match water deliveries to crop water requirements, thereby reducing river diversions. The DSS uses linear programming logic with an objective function to find an optimum water delivery schedule for the service areas in an irrigation system. Water delivery using the DSS is accomplished using three modules: a water demand module, a supply network module and an irrigation scheduling module. Limited field validation shows that the DSS is indeed able to correctly model the irrigation delivery system, and recommend water delivery schedules that are reasonable. Future plans include more intensive field validation and implementation in the Middle Rio Grande irrigation service area.

Calibration of the 10HS Soil Moisture Sensor for Southwest Florida Agricultural Soils

AbstractPrecision irrigation is crucial in decreasing water demands of irrigated agriculture, which account for the largest source of water withdrawal in most regions. One necessity of precision irrigation is the knowledge of soil moisture content in the root zone of irrigated crops. Dielectric soil moisture sensors can provide this information at a relatively low cost (

Validation of a Decision Support System for Improving Irrigation System Performance

100) compared with other techniques; however, their accuracy cannot be guaranteed in all soils without site-specific calibration, the need for which has limited the use of these sensors. This study examined the Decagon 10HS soil moisture sensor in order to determine the accuracy of the manufacturer-supplied calibration equation on southwest Florida (SWFL) agricultural soils, and analyze whether it performs consistently in different soils found in SWFL. Laboratory calibration of the 10HS was done on four SWFL soils that represent the majority of agricultural land in the region and regression calibration equations were obtained. It was foun...

Implementation of a Decision Support System for Improving Irrigation Water Delivery: Case Study

AbstractTo address water shortage and improve water delivery operations, decision support systems (DSSs) have been developed and utilized throughout the United States and the world. One critical aspect that is often neglected during the development and implementation of DSSs is validation, which can result in flawed water distribution and rejection of the DSS by water users and managers. This paper presents the results of a significant validation effort for a DSS in the Middle Rio Grande Conservancy District (MRGCD). The validation resulted in a refined application efficiency of 45%, a refined readily available water for farmers to irrigate to a value of 20%, and a Nash-Sutcliffe modeling efficiency of 0.86 for soil moisture depletion patterns. Overall, the validation and refinement of input parameters resulted in a DSS model that accurately predicts evaportranspiration and can be used to schedule water delivery. The refinement of the DSS input parameters resulted in an increased 15,600 acre-ft diversion ...

Linking a Developed Decision Support System with Advanced Methodologies for Optimized Agricultural Water Delivery

AbstractDecision support systems (DSSs) for irrigation system management have many benefits, which include water savings and the development of optimal water delivery schedules, while maintaining farmer productivity. To address water shortage and improve water delivery, DSSs have been developed and utilized throughout the United States and the world and can be used to predict crop depletions using weather data to schedule water delivery on the basis of crop demand. The overall utility of DSSs is that they allow managers to continue water delivery and equitably distribute supplies during a water shortage. For a decision support system to be successfully utilized, the complicated challenge of implementation needs to be addressed. Decision support system implementation is often met with harsh resistance from water users and managers alike, and, in many cases, a scientifically sound model is often rejected because of misinformation and lack of user education. This paper presents the successful implementation ...

A Low-Cost Approach for Rapidly Creating Demonstration Models for Hands-On Learning.

Water is the lifeblood of the American West and the foundation of its economy, but it remains its scarcest resource. The explosive population growth in the Western United States, the emerging additional need for water for environmental uses, and the national importance of the domestic food production are driving major conflicts between these competing water uses. Irrigated agriculture in particular is by far the largest water user of diverted water – 80% country wide and 90% in the Western U.S – and since it is perceived to be a comparatively inefficient user, it is frequently asked to decrease its water consumption. The case of the Middle Rio Grande illustrates the problem very well. The Rio Grande is the ecological backbone of the Chihuahuan Desert region in the western United States, and supports its dynamic and diverse ecology, including the fish and wildlife habitat. The Rio Grande Silvery Minnow is a federally listed as endangered species, and irrigated agriculture in the Middle Rio Grande has come under increasing pressure to reduce its water consumption, while maintaining the desired level of service to its water users. Irrigated agriculture in the Western United States has traditionally been the backbone of the rural economy. The climate in the American West with low annual rainfall of 10 to 14 inches is not conducive to dry land farming. Topography in the West is characterized by the Rocky Mountains which accumulate significant snowfall, and the peaks of the snowmelt hydrograph are stored in reservoirs allowing for irrigation throughout the summer crop growing season. Of the total available surface water irrigated agriculture uses roughly 80 to 90% (Oad and Kullman, 2006). The combined demands of agriculture, urban, and industrial sectors in the past have left little water for fish and wildlife. Since irrigated agriculture uses roughly 80 to 90% of surface water in the West, it is often targeted to decrease diversions. Due to wildlife concerns and demands from an ever growing urban population, the pressure for flow reductions on irrigated agriculture increases every year. In order to sustain itself and deal with external pressure for reduced river diversions irrigated agriculture has to become more efficient in its water consumption. This chapter focuses on research regarding improving water delivery operations in the Middle Rio Grande Conservancy District system through the use of a decision support system linked with advanced infrastructure, methodologies, and technology.

Evolution of Heterogeneous Mixed Siliciclastic/Carbonate Aquifers Containing Metastable Sediments

ABSTRACT Demonstration models allow students to readily grasp theory and relate difficult concepts and equations to real life. However drawbacks of using these demonstration models are that they are can be costly to purchase from vendors or take a significant amount of time to build. These two limiting factors can pose a significant obstacle for adding demonstrations to the curriculum. This article presents an assignment to overcome these obstacles, which has resulted in 36 demonstration models being added to the curriculum. The article also presents the results of student performance on course objectives as a result of the developed models being used in the classroom. Overall, significant improvement in student learning outcomes, due to the addition of demonstration models, has been observed.

Using an ADCP to determine canal seepage loss in an irrigation district

Mixed carbonate and siliciclastic marine sediments commonly become freshwater aquifers in eastern coastal regions of the United States and many other global locations. As these deposits age, the carbonate fraction of the sediment is commonly removed by dissolution and the aquifer can become a solely siliciclastic system or contain zones or beds of pure quartz sand. During aquifer evolution, the sediment grain size characteristics, hydraulic conductivity, and porosity change. An investigation of these changes using mixed carbonate/siliciclastic sediment samples collected from a modern barrier island beach in southern Florida showed that the average mean grain diameter decreased with removal of the carbonate fraction, but the average hydraulic conductivity and porosity increased slightly, but not to statistical significance. This counterintuitive result occurs because of the change in the pore types from a combined shelter and intergranular pore system producing a dual porosity system in the mixed sediments to a single intergranular pore system in the siliciclastic sediment fraction. Within the mixed carbonate/siliciclastic sediment, in the pure carbonate fraction, large shell fractions form grain-supported large pores, which become filled with sand-sized quartz as the shell fragments decrease in size or as the sediment becomes compacted. The hydraulic conductivity increases because the shell fragments that were oriented perpendicular to flow caused an increase in the length of the flow path, or a larger scale tortuosity, compared with the flow through pure quartz sand.