Andrew Keller - Academia.edu (original) (raw)
Papers by Andrew Keller
RePEc: Research Papers in Economics, 1996
Those, who are strongly wedded to what I shall call the classical theory, will fluctuate, I expec... more Those, who are strongly wedded to what I shall call the classical theory, will fluctuate, I expect, between a belief that I am quite wrong and a belief that I am saying nothing new.
Applied Engineering in Agriculture, 1987
A weather generating model called WMAKER was developed at Utah State University to simulate daily... more A weather generating model called WMAKER was developed at Utah State University to simulate daily climatological values using monthly average values and standard deviations of precipitation, temperature, number of rainy days and potential evapotranspiration. The data generated by the WMAKER Model were used to simulate yield probability values for corn under rainfed and irrigated agriculture for stations of Quixeramobim and Brasilia (Brazil) and San Andres and La Union (El Salvador), using the PLANTGRO and CERES-Maize models. The yield probability values were then calculated using actual daily climatic data. It was concluded that the results obtained with actual data were in close agreement with those calculated by the WMAKER Model. The IBSNAT project will soon have yield models available for 10 crops. With adequate documentation, training programs and a monthly data base, these models can become powerful tools for increasing agricultural production, particularly in the developing countries.
Remote sensing data and a surface energy balance model (SEBAL) were used to calculate monthly and... more Remote sensing data and a surface energy balance model (SEBAL) were used to calculate monthly and annual evapotranspiration (ET) and biomass production for the Imperial Irrigation District (IID), a large predominantly agricultural region located in far southern California. The SEBAL model utilizes high resolution thermal infrared data from Landsat imagery, providing spatially distributed ET at 30 meter scale. IID is
Agricultural Economics, 2000
Increasing competition for water across sectors increases the importance of the river basin as th... more Increasing competition for water across sectors increases the importance of the river basin as the appropriate unit of analysis to address the challenges facing water resources management; and modeling at this scale can provide essential information for policymakers in their resource allocation decisions. This paper introduces an integrated economichydrologic modeling framework that accounts for the interactions between water allocation, farmer input choice, agricultural productivity, nonagricultural water demand, and resource degradation in order to estimate the social and economic gains from improvement in the allocation and efficiency of water use. The model is applied to the Maipo River Basin in Chile. Economic benefits to water use are evaluated for different demand management instruments, including markets in tradable water rights, based on production and benefit functions with respect to water for the agricultural and urbanindustrial sectors.
Presented at Ground water and surface water under stress: competition, interaction, solutions: a ... more Presented at Ground water and surface water under stress: competition, interaction, solutions: a USCID water management conference on October 25-28, 2006 in Boise, Idaho.Includes bibliographical references.It has been shown that the temperature-time threshold (TTT) method of automatic irrigation scheduling is a viable alternative to traditional soil water based irrigation scheduling in the Southern High Plains. This method was used to fully automate a center pivot in the panhandle of Texas. An array of 16 IRTCs were mounted on the pivot and connected to a datalogger also mounted on the pivot. A separate array of IRTCs were located in stationary positions in the field and connected to a separate datalogger. Two different spread spectrum (900 MHz) radios were connected to a desktop computer located nearby that queried both dataloggers, got pivot status information, and sent commands to the center pivot control panel. Using scheduled data collection intervals, this computer was able to...
International 1995 Center for Economic Policy Studies The Discussion Paper series is part of Winr... more International 1995 Center for Economic Policy Studies The Discussion Paper series is part of Winrock International's effort to develop innovative thinking and disseminate new information about agricultural and rural development. The papers are intended to contribute to the body of knowledge on how development process works, encourage productive debate of development issues, provide a forum for informed opinion, and generate new focal points for research. The papers represent only the opinion of the authors and not necessarily that of Winrock or any affiliated institution. Winrock International for Agricultural Development is a private, nonprofit organization whose mission is to reduce poverty and hunger through agricultural and
Efficiency of water resources is essential; just as important is the terminology that describes i... more Efficiency of water resources is essential; just as important is the terminology that describes it. Paradoxes in terminologies used by various international institutions and professionals in the agricultural, urban and environmental domains are examined. Integrated terminologies are proposed, starting from flow-path types in water balance and expanded into the "macro, meso, and micro-efficiencies" (3ME) formulation. The 3ME is a systemic framework based on the principle of the conservation of mass, integrating water-flow paths of a water system, their beneficial and quality attributes (the usefulness criterion), climate, and two types of water totals. These terminologies, with nine examples for urban (three types) and agricultural areas (rainfed, surface, drip and sprinkler), are used to discuss the 3ME framework and possible flawed policy implications.
Impacts of Global Climate Change, 2005
Center for Economic Policy Studies The Discussion Paper series is part of Winrock International's... more Center for Economic Policy Studies The Discussion Paper series is part of Winrock International's effort to develop innovative thinking and disseminate new information about agricultural and rural development. The papers are intended to contribute to the body of knowledge on how development process works, encourage productive debate of development issues, provide a forum for informed opinion, and generate new focal points for research. The papers represent only the opinion of the authors and not necessarily that of Winrock or any affiliated institution. Winrock International for Agricultural Development is a private, nonprofit organization whose mission is to reduce poverty and hunger through agricultural and rural development that is sustainable and environmentally sound.
Ecological Monographs, 2008
Many farmers in India and elsewhere surface irrigate their small fields with water from wells hav... more Many farmers in India and elsewhere surface irrigate their small fields with water from wells having small average discharges. They are being assisted in converting to very low-cost drip systems that are nonproprietary and manufactured locally. These drip systems are affordable and payback is quick in view of the reported water savings of 50 to 80 percent and yield increases of 30 to 50 percent. The systems operate at pressure heads of less than 3 meters (10 feet), require minimal filtration, use cheap recycled plastic sub-mains (manifolds), and use simple drip-tape with short lengths of microtubes for emitters. This presentation covers the following aspects of these low-cost drip systems: a) farmers experiences and profitability; b) technology development and marketing assistance; c) system specifications and component costs; d) local manufacturing requirements and costs; e) system performance characteristics; and f) design tools and procedures.
Hourly inflow and spillage rates from three lateral canals in the Imperial Irrigation District in... more Hourly inflow and spillage rates from three lateral canals in the Imperial Irrigation District in Southern California were measured for seven months and subsequently analyzed to identify any potential correlation between headgate flow unsteadiness and total spillage. The study produced significant evidence to show that reduced inflow fluctuations result in a decrease of total spillage. Estimates indicate that reducing the unsteadiness of lateral inflow by 50 percent could decrease spillage by 1 percent of the total inflow. For these laterals, the decrease equals approximately 20 percent of the total spillage.
Presented at Ground water and surface water under stress: competition, interaction, solutions: a ... more Presented at Ground water and surface water under stress: competition, interaction, solutions: a USCID water management conference on October 25-28, 2006 in Boise, Idaho.
The lateral interceptor concept was conceived in the wake of a water conservation effort to reduc... more The lateral interceptor concept was conceived in the wake of a water conservation effort to reduce several sources of water loss typical of irrigation districts. These sources include operational discharges from lateral canals and excess on-farm deep percolation and tailwater. In addition to conservation, a lateral interceptor system can provide its water users the flexibility of ordering and shutting off when desired under a fixed-arranged delivery schedule.
Agricultural Water Management
The landscape of water in Utah is changing due to population growth, conversion of agricultural l... more The landscape of water in Utah is changing due to population growth, conversion of agricultural land to urban development, and increasing awareness of water scarcity. At the same time, Utah is experiencing a growing number of urban and small farms, but knowledge of water use in this sector is limited. Better understanding of what occurs at the field level on urban and small farms can aid state water use estimates and conservation efforts, and assist farmers in moving towards wiser water management. For the 2015 growing season, we performed irrigation evaluations for 24 urban and small farms in Cache Valley, Utah and we explore the results through case studies and identify trends among gross irrigation depth and field variables including field size, irrigation method, application uniformity, and scheduling practices. Results show a great degree of heterogeneity in irrigation methods, equipment used, and management practices. The beneficial consumed fraction of irrigation water ranged from 0.06 to 1.0. Small fields had lower application uniformities and greater irrigation depths than large fields. Surface irrigated fields had higher irrigation depths than sprinkle and drip irrigated fields. Additionally, fields using a fixed irrigation schedule had higher depths than fields that were irrigated inconsistently due to other factors. The results show that urban and small farm irrigators need improved knowledge of proper irrigation management. Irrigators, university extension services, and state water authorities working in this sector need to recognize the link between proper management and total water use, and focus more efforts on improving management, specifically how to use 1) low-cost methods to measure flow rates, 2) simple irrigation scheduling tools, and 3) improve application uniformity.
Introduction 3 The Composition of an Idealized IWS 4 Classical irrigation efficiency 4 Effective ... more Introduction 3 The Composition of an Idealized IWS 4 Classical irrigation efficiency 4 Effective irrigation efficiency 7 The Composition of a Real IWS 8 Leaching requirements 8 Computing E C and E E values for an actual IWS 9 Real Water Savings 11 Managing the closure 12 Who is responsible for conserving freshwater? 12 Policy Implications of IWS Closure 13 Literature Cited 15
Impacts of Global Climate Change, 2005
The Imperial Irrigation Decision Support System (IIDSS) is a comprehensive tool for evaluating st... more The Imperial Irrigation Decision Support System (IIDSS) is a comprehensive tool for evaluating structural and operational modifications to the Imperial Irrigation District's delivery and drainage systems. The IIDSS toolkit contains several modules including the MODSIM hydrologic model. IIDSS was originally developed as an analysis tool for use in preparation of the environmental documentation for the water transfer between the Imperial Irrigation District and the San Diego County Water Authority. Specifically, the model was used to investigate how various scenarios for meeting the water conservation requirements of the transfer would affect flows and water quality throughout the District's irrigation and drainage system and impact discharges to the Salton Sea. Now that the transfer is in the process of being implemented, the IIDSS is evolving from a planning tool to an operational aid. This paper begins with background on IID and on the water transfer agreement. The paper then discusses the original formulation of the IIDSS and how the system is being modified to improve its functionality as a planning and operational tool.
RePEc: Research Papers in Economics, 1996
Those, who are strongly wedded to what I shall call the classical theory, will fluctuate, I expec... more Those, who are strongly wedded to what I shall call the classical theory, will fluctuate, I expect, between a belief that I am quite wrong and a belief that I am saying nothing new.
Applied Engineering in Agriculture, 1987
A weather generating model called WMAKER was developed at Utah State University to simulate daily... more A weather generating model called WMAKER was developed at Utah State University to simulate daily climatological values using monthly average values and standard deviations of precipitation, temperature, number of rainy days and potential evapotranspiration. The data generated by the WMAKER Model were used to simulate yield probability values for corn under rainfed and irrigated agriculture for stations of Quixeramobim and Brasilia (Brazil) and San Andres and La Union (El Salvador), using the PLANTGRO and CERES-Maize models. The yield probability values were then calculated using actual daily climatic data. It was concluded that the results obtained with actual data were in close agreement with those calculated by the WMAKER Model. The IBSNAT project will soon have yield models available for 10 crops. With adequate documentation, training programs and a monthly data base, these models can become powerful tools for increasing agricultural production, particularly in the developing countries.
Remote sensing data and a surface energy balance model (SEBAL) were used to calculate monthly and... more Remote sensing data and a surface energy balance model (SEBAL) were used to calculate monthly and annual evapotranspiration (ET) and biomass production for the Imperial Irrigation District (IID), a large predominantly agricultural region located in far southern California. The SEBAL model utilizes high resolution thermal infrared data from Landsat imagery, providing spatially distributed ET at 30 meter scale. IID is
Agricultural Economics, 2000
Increasing competition for water across sectors increases the importance of the river basin as th... more Increasing competition for water across sectors increases the importance of the river basin as the appropriate unit of analysis to address the challenges facing water resources management; and modeling at this scale can provide essential information for policymakers in their resource allocation decisions. This paper introduces an integrated economichydrologic modeling framework that accounts for the interactions between water allocation, farmer input choice, agricultural productivity, nonagricultural water demand, and resource degradation in order to estimate the social and economic gains from improvement in the allocation and efficiency of water use. The model is applied to the Maipo River Basin in Chile. Economic benefits to water use are evaluated for different demand management instruments, including markets in tradable water rights, based on production and benefit functions with respect to water for the agricultural and urbanindustrial sectors.
Presented at Ground water and surface water under stress: competition, interaction, solutions: a ... more Presented at Ground water and surface water under stress: competition, interaction, solutions: a USCID water management conference on October 25-28, 2006 in Boise, Idaho.Includes bibliographical references.It has been shown that the temperature-time threshold (TTT) method of automatic irrigation scheduling is a viable alternative to traditional soil water based irrigation scheduling in the Southern High Plains. This method was used to fully automate a center pivot in the panhandle of Texas. An array of 16 IRTCs were mounted on the pivot and connected to a datalogger also mounted on the pivot. A separate array of IRTCs were located in stationary positions in the field and connected to a separate datalogger. Two different spread spectrum (900 MHz) radios were connected to a desktop computer located nearby that queried both dataloggers, got pivot status information, and sent commands to the center pivot control panel. Using scheduled data collection intervals, this computer was able to...
International 1995 Center for Economic Policy Studies The Discussion Paper series is part of Winr... more International 1995 Center for Economic Policy Studies The Discussion Paper series is part of Winrock International's effort to develop innovative thinking and disseminate new information about agricultural and rural development. The papers are intended to contribute to the body of knowledge on how development process works, encourage productive debate of development issues, provide a forum for informed opinion, and generate new focal points for research. The papers represent only the opinion of the authors and not necessarily that of Winrock or any affiliated institution. Winrock International for Agricultural Development is a private, nonprofit organization whose mission is to reduce poverty and hunger through agricultural and
Efficiency of water resources is essential; just as important is the terminology that describes i... more Efficiency of water resources is essential; just as important is the terminology that describes it. Paradoxes in terminologies used by various international institutions and professionals in the agricultural, urban and environmental domains are examined. Integrated terminologies are proposed, starting from flow-path types in water balance and expanded into the "macro, meso, and micro-efficiencies" (3ME) formulation. The 3ME is a systemic framework based on the principle of the conservation of mass, integrating water-flow paths of a water system, their beneficial and quality attributes (the usefulness criterion), climate, and two types of water totals. These terminologies, with nine examples for urban (three types) and agricultural areas (rainfed, surface, drip and sprinkler), are used to discuss the 3ME framework and possible flawed policy implications.
Impacts of Global Climate Change, 2005
Center for Economic Policy Studies The Discussion Paper series is part of Winrock International's... more Center for Economic Policy Studies The Discussion Paper series is part of Winrock International's effort to develop innovative thinking and disseminate new information about agricultural and rural development. The papers are intended to contribute to the body of knowledge on how development process works, encourage productive debate of development issues, provide a forum for informed opinion, and generate new focal points for research. The papers represent only the opinion of the authors and not necessarily that of Winrock or any affiliated institution. Winrock International for Agricultural Development is a private, nonprofit organization whose mission is to reduce poverty and hunger through agricultural and rural development that is sustainable and environmentally sound.
Ecological Monographs, 2008
Many farmers in India and elsewhere surface irrigate their small fields with water from wells hav... more Many farmers in India and elsewhere surface irrigate their small fields with water from wells having small average discharges. They are being assisted in converting to very low-cost drip systems that are nonproprietary and manufactured locally. These drip systems are affordable and payback is quick in view of the reported water savings of 50 to 80 percent and yield increases of 30 to 50 percent. The systems operate at pressure heads of less than 3 meters (10 feet), require minimal filtration, use cheap recycled plastic sub-mains (manifolds), and use simple drip-tape with short lengths of microtubes for emitters. This presentation covers the following aspects of these low-cost drip systems: a) farmers experiences and profitability; b) technology development and marketing assistance; c) system specifications and component costs; d) local manufacturing requirements and costs; e) system performance characteristics; and f) design tools and procedures.
Hourly inflow and spillage rates from three lateral canals in the Imperial Irrigation District in... more Hourly inflow and spillage rates from three lateral canals in the Imperial Irrigation District in Southern California were measured for seven months and subsequently analyzed to identify any potential correlation between headgate flow unsteadiness and total spillage. The study produced significant evidence to show that reduced inflow fluctuations result in a decrease of total spillage. Estimates indicate that reducing the unsteadiness of lateral inflow by 50 percent could decrease spillage by 1 percent of the total inflow. For these laterals, the decrease equals approximately 20 percent of the total spillage.
Presented at Ground water and surface water under stress: competition, interaction, solutions: a ... more Presented at Ground water and surface water under stress: competition, interaction, solutions: a USCID water management conference on October 25-28, 2006 in Boise, Idaho.
The lateral interceptor concept was conceived in the wake of a water conservation effort to reduc... more The lateral interceptor concept was conceived in the wake of a water conservation effort to reduce several sources of water loss typical of irrigation districts. These sources include operational discharges from lateral canals and excess on-farm deep percolation and tailwater. In addition to conservation, a lateral interceptor system can provide its water users the flexibility of ordering and shutting off when desired under a fixed-arranged delivery schedule.
Agricultural Water Management
The landscape of water in Utah is changing due to population growth, conversion of agricultural l... more The landscape of water in Utah is changing due to population growth, conversion of agricultural land to urban development, and increasing awareness of water scarcity. At the same time, Utah is experiencing a growing number of urban and small farms, but knowledge of water use in this sector is limited. Better understanding of what occurs at the field level on urban and small farms can aid state water use estimates and conservation efforts, and assist farmers in moving towards wiser water management. For the 2015 growing season, we performed irrigation evaluations for 24 urban and small farms in Cache Valley, Utah and we explore the results through case studies and identify trends among gross irrigation depth and field variables including field size, irrigation method, application uniformity, and scheduling practices. Results show a great degree of heterogeneity in irrigation methods, equipment used, and management practices. The beneficial consumed fraction of irrigation water ranged from 0.06 to 1.0. Small fields had lower application uniformities and greater irrigation depths than large fields. Surface irrigated fields had higher irrigation depths than sprinkle and drip irrigated fields. Additionally, fields using a fixed irrigation schedule had higher depths than fields that were irrigated inconsistently due to other factors. The results show that urban and small farm irrigators need improved knowledge of proper irrigation management. Irrigators, university extension services, and state water authorities working in this sector need to recognize the link between proper management and total water use, and focus more efforts on improving management, specifically how to use 1) low-cost methods to measure flow rates, 2) simple irrigation scheduling tools, and 3) improve application uniformity.
Introduction 3 The Composition of an Idealized IWS 4 Classical irrigation efficiency 4 Effective ... more Introduction 3 The Composition of an Idealized IWS 4 Classical irrigation efficiency 4 Effective irrigation efficiency 7 The Composition of a Real IWS 8 Leaching requirements 8 Computing E C and E E values for an actual IWS 9 Real Water Savings 11 Managing the closure 12 Who is responsible for conserving freshwater? 12 Policy Implications of IWS Closure 13 Literature Cited 15
Impacts of Global Climate Change, 2005
The Imperial Irrigation Decision Support System (IIDSS) is a comprehensive tool for evaluating st... more The Imperial Irrigation Decision Support System (IIDSS) is a comprehensive tool for evaluating structural and operational modifications to the Imperial Irrigation District's delivery and drainage systems. The IIDSS toolkit contains several modules including the MODSIM hydrologic model. IIDSS was originally developed as an analysis tool for use in preparation of the environmental documentation for the water transfer between the Imperial Irrigation District and the San Diego County Water Authority. Specifically, the model was used to investigate how various scenarios for meeting the water conservation requirements of the transfer would affect flows and water quality throughout the District's irrigation and drainage system and impact discharges to the Salton Sea. Now that the transfer is in the process of being implemented, the IIDSS is evolving from a planning tool to an operational aid. This paper begins with background on IID and on the water transfer agreement. The paper then discusses the original formulation of the IIDSS and how the system is being modified to improve its functionality as a planning and operational tool.