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ARS Home Pacific West Area Tucson, Arizona SWRC Docs





- Research Overview
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- Experimental Watersheds

Science Results (Early 2006)headline bar 
 
 Monitoring coarse sediment particle displacement using a radio frequency identification system  Nichols, M.H.SouthwestWatershedResearchCenter  Coarse particles make up a relatively high contribution to overall sediment yield in ephemeral alluvial channels.A radio frequency identification system was developed and implemented to monitor the displacement of coarse particles following runoff in two upland, ephemeral channels on the USDA-ARS Walnut Gulch Experimental Watershed in southeasternArizona.Sediment transporting flows are typically of short duration with rapidly rising and falling hydrographs. Commercially available radio frequency identification components including transponders, an antenna, a reader, and software were used to develop a system for locating particles under field conditions.During the 2003 field season 124 particles were located following four runoff events in two ephemeral channels.A total of 340 particle positions were measured with a differential geopositioning system after each particle was located with the radio frequency identification system.The overall recovery rate was 96%. The passive transponder system offers the advantages of low cost, consistent results under harsh environmental conditions, and no need for a power supply in the particle. Buried particles can be located and identified without disturbing channel bed material. The radio frequency identification system can be used to efficiently collect data for developing sediment transport equations and improving mathematical models for simulating sediment transport under natural runoff conditions.   AGISframework for surface-layer soil moisture estimation combining satellite measurements and land surface modeling with soil physical property estimation  Tischler, M.US ARMY Corps of Engineers Garcia, M.NASA Peters-Lidard, C.NASA Moran, M.S.SouthwestWatershedResearchCenter Miller, S.UniversityofWyoming Thoma, D.SouthwestWatershedResearchCenter Kumar, S.UniversityofMaryland Geiger, J.NASA  In a cooperative project with ARS and the U.S. Army Corps of Engineers, satellite image data and simulation modeling were combined for the estimation of surface soil moisture at the watershed scale.The Army wanted a product that was user friendly and allowed visualization by users in the field.A Geographic Information System (GIS) provided a good framework to integrate the models and data on a Windows platform.As a result, a graphical user interface exists for a user to easily parameterize the land surface model, perform data format conversions.This system was designed and developed with the military user in mind, for use in trafficability assessment, construction engineering, and countermine efforts.It allows a user with little formal background in hydrological sciences, remote sensing, computer science, or soil science to determine spatial surface soil moisture using a scientifically sound procedure with robust modeling tools for use in a variety of applications.  Mapping surface roughness and soil moisture using multi-angle radar imagery without ancillary data  Rahman, M. M.UniversityofArizona Moran, M.S.SouthwestWatershedResearchCenter Thoma, D.SouthwestWatershedResearchCenter Bryant, R.UniversityofArizona Holifield-Collins, C.SouthwestWatershedResearchCenter Orr, B. J.UniversityofArizona Tischler, M.USARMYEngineerResearch & DevelopmentCenter  Information about the distribution of surface soil moisture is important for a number of applications ranging from the management of agricultural resources to determining vehicle mobility.Satellite images of radar backscatter have been used for mapping surface soil moisture.However, this satellite-based method requires extensive information about surface roughness that is usually acquired by time-consuming and imprecise field measurements.In this study, a method was developed to map surface roughness using multiple radar images as a replacement for field-collected ancillary data.Results indicate that image-derived surface roughness was larger than field measured roughness. This confirms that the subsurface roughness caused by the rock fragments plays an important role in interpreting radar backscatter.This hypothesis was further supported by results showing that there was good association between image-derived soil moisture and field measured soil moisture.This is a breakthrough in mapping surface soil moisture because it is entirely image based and does not require on-site measurements.This method could be used to map surface soil moisture of large regions using sensors already aboard currently orbiting satellites.  Monitoringheadcut migration over four decades on a rangeland area in the southwesternUnited States  Zieke-Zapp, D.University of Bern,Switzerland Nichols, M.HSouthwestWatershedResearchCenter Laderach, C.University of Bern,Switzerland  Gullies are a dominant landscape feature throughout the southwesternUnited States. These gullies are a source of sediment that can be carried downchannel by flash floods generated during summer thunderstorms. Sediment is contributed by both the banks of the gully and the headcut, or vertical face, at the upper end of the gully. Research was undertaken to compute the rate of headcut advance for a gully in southeasternArizonaover a period of approximately four decades.An active headcut in the USDA-ARS Walnut Gulch Experimental Watershed was surveyed in spring of 2004.The data were compared to survey records dating back to 1966, 1973, 1977, and 1981 to calculate the long term migration rates of the headcut and to estimate the volume that was eroded between 1966 and 2004.Headcutting remains a major sediment source in semiarid regions and quantifying the relative contribution of sediment from gully erosion to that of uplands is important for deciding where to focus mitigation efforts. Sediment Yield From Small Semiarid Watersheds  Nichols. M. H.SouthwestWatershedResearchCenter  Sediment is one of the principle pollutants of surface water in theUnited States.One measure of the amount of sediment that leaves a watershed is sediment yield. Sediment yield has been measured on the United States Department of Agriculture - Agricultural Research Service Walnut Gulch Experimental Watershed nearTombstoneArizonasince the 1950s. Historic measurements were combined with recent measurements and baseline small watershed sediment yield data are now available for semiarid rangelands. Within the 150 km sq WGEW, sediment yield from upland watersheds ranged from 0.6 t••ha-1••yr-1to 3.7 t••ha-1••yr-1.This research is providing information that can be used to evaluate the impacts of watershed management on downstream sediment yield.  The sensitivity of ecosystem carbon exchange to seasonal precipitation and woody plant communities  Potts, D. L.UniversityofArizona Huxman, T.E.UniversityofArizona Scott, R.L.SouthwestWatershedResearchCenter Williams, D.G.UniversityofWyoming Goodrich,D.C.SouthwestWatershedResearchCenter  Arid and semi-arid regions account for approximately one-third of the land mass of earth.These regions are experiencing continued pressure from population growth in many parts of the world.Water is a critical resource in these regions and is often in short supply.Detailed study of water resources and the hydrology of semi-arid regions is important if we are to continue to populate and use these regions.The Walnut Gulch Experimental Watershed, operated by the U.S. Dept. of Agriculture, Agricultural Research Service was established to observe and better understand water movement and the effects of land use on watershed hydrology in semi-arid regions.Our understanding of water and hydrology in semi-arid regions has been greatly enhanced through numerous studies of rainfall, runoff, and soil moisture patterns at this experimental watershed.In this study, an improved method to estimate surface soil moisture is developed using remotely sensed data obtained from an airplane.This method can also be applied to data obtained from orbiting satellites.The advantage of the newly developed method is that is allows estimation of surface soil moisture over smaller areas by combining information on surface temperature and local weather conditions.Soil moisture is important for a range of uses including seeding establishment, soil evaporation, runoff estimation, and mobility of vehicles for cross-country travel.All of these applications can be improved by having soil moisture data with higher spatial resolution derived from the methods developed in this study.  A downscaling method for distributing surface soil moisture within a microwave pixel: Application to Monsoon'90  Merlin, O.CESBIO, France Chehbouni, A.CESBIO, France Kerr, Y. H.CESBIO, France Goodrich,D.C.SouthwestWatershedResearchCenter  Arid and semi-arid regions account for approximately one-third of the land mass of earth.These regions are experiencing continued pressure from population growth in many parts of the world.Water is a critical resource in these regions and is often in short supply.Detailed study of water resources and the hydrology of semi-arid regions is important if we are to continue to populate and use these regions.The Walnut Gulch Experimental Watershed, operated by the U.S. Dept. of Agriculture, Agricultural Research Service was established to observe and better understand water movement and the effects of land use on watershed hydrology in semi-arid regions.Our understanding of water and hydrology in semi-arid regions has been greatly enhanced through numerous studies of rainfall, runoff, and soil moisture patterns at this experimental watershed.In this study, an improved method to estimate surface soil moisture is developed using remotely sensed data obtained from an airplane.This method can also be applied to data obtained from orbiting satellites.The advantage of the newly developed method is that is allows estimation of surface soil moisture over smaller areas by combining information on surface temperature and local weather conditions.Soil moisture is important for a range of uses including seeding establishment, soil evaporation, runoff estimation, and mobility of vehicles for cross-country travel.All of these applications can be improved by having soil moisture data with higher spatial resolution derived from the methods developed in this study.   Relationships between land-useDOM, and inorganic nitrogen concentrations in a semi-arid catchment.  Lemmon, M.M.UniversityofArizona Brooks, P.D.UniversityofArizona Goodrich,D.C.SouthwestWatershedResearchCenter   Unregulated riparian river systems are very rare in arid and semi-arid regions of theUnited Statesyet they harbor a high percentage of the biological diversity.The health of these riparian systems can be influenced by the hydrology and land use of the surrounding watershed.To investigate this influence six chemical sampling events were performed along a large reach of the Upper San Pedro River in southeastArizonabefore, during, and after the 2002 monsoon season. We found that before and after the monsoon season, the river was divided into three distinct reaches.Upper and lower reaches had isolated places with small river flows sustained by localized groundwater inputs.The middle reach had widespread groundwater inputs with higher river flows and greater downstream movement of the chemicals measured in the water. Water chemistry during low flow was closely related to local riparian land use.During the monsoon season, stream flows increased 10 fold and mixed the chemicals measured in the stream water throughout the entire river riparian area. The heavy rains from the summer monsoon flushed organic matter and other nutrients into the river.These nutrients appeared to be trapped in the protected portions of the San Pedro riparian system, while outside the protected portion they were not.This research demonstrates that seasonal changes in river flows in the riparian system control the effects of land use and land cover on surface water quality for small parts of the riparian area and over the total length of the river.   Chapter 9:Integrating Science and Policy for Water Management  Richter, H.UniversityofArizona Goodrich,D.C.SouthwestWatershedResearchCenter Browning-Aiken, A.UniversityofArizona Varady, R.UniversityofArizona  Freshwater and the myriad ecosystems which originate from them are indispensable to human health and survival. Yet population growth, climatic variability, and land uses such as mining and agricultural practices along the U.S.-Mexico border challenge our ability to manage clean groundwater aquifers in this region that support populations, agriculture, industry and riparian ecosystems.TheSanPedroBasinwhich originates in northernSonora,Mexicoand flow north into southeasternArizonais a internationally known example of such a resource.As the Southwest grapples with ways to increase water supplies and ensure water quality for its burgeoning population, various institutional and political drivers of change, including government agencies at all levels and elected officials trying to serve their constituents interests, directly affect specific water management policies in the region. Within the Upper San Pedro Basin, a variety of internal local (municipal/county level) and external (state and federal level) drivers have affected water management policy differently throughout the basin. As a result, stakeholders in the three subwatersheds within the Upper San Pedro Basin have responded very differently to their individual groundwater management challenges over time. This chapter provides a description of the collaborative efforts of scientists, agency representatives, non-governmental organizations, elected officials, and other stakeholders to address water policy and management problems in the Upper San Pedro River Basin.  Hydrologic requirements of and evapotranspiration by riparian vegetation along theSanPedroRiver,Arizona  Leenhouts, J.USGS Scott, R.L.SouthwestWatershedResearchCenter Stromburg, J.ArizonaStateUniversity  For many of the human settlements in the Southwest, groundwater from regional aquifers has become the largest single source of fresh water for human communities. This reliance on groundwater has led to a large effort to further our understanding of the water balance of these large regional groundwater systems. Two critical component of this water balance are the amount of water used by the riparian system and the water conditions that are needed to support various assemblages of riparian plants. A multiyear, multidisciplinary research effort was made to provide information about these two components for a federally protected portion of the Upper San Pedro River.This "Fact Sheet" is intended to summarize the detailed results reported in a large USGS report and make this information available to a broader public audience.  Changes in vegetation condition and surface fluxes during NAME 2004  Watts, J. C.University of Sonora,Mexico Scott, R.L.SouthwestWatershedResearchCenter Garatuza-Payan, J.ITSON,Sonora,Mexico Rodriguez, J.C.IMADES Prueger, J.H.USDA-ARSAmes, IA Kustas, W.P.USDA-ARS Beltsville, MD Douglas, M.NOAA  The North American Monsoon (NAM) controls warm season climate and is responsible to providing the majority of rainfall over much of southwesternNorth America. Knowing how ecosystems respond to this input of rainfall is critical to understanding how surface vegetation response may affect monsoon intensity.Unfortunately, little has been documented about this vegetation response across much of theNAMregion.In 2004 US and Mexican scientists embarked on a comprehensive study ofNAM.As a part of this work, surface energy balance measurements were made over seven different ecosystem types in Sonora, Mexico and Arizona, USA to better understand how land surface vegetation change alters the way that energy is exchanged between the atmosphere and land surface.Large changes in vegetation, monitored by satellites, were observed, especially for the subtropical sites inSonora. The surface net radiation was consistent with the previous observations, being largest for surfaces that are transpiring and cool, and smallest for surfaces that are dry and hot. The largest evaporation rates were observed for the subtropical and riparian vegetation.These results suggest site-to-site variability in the surface fluxes was large and highly depended upon local rainfall. Nevertheless, the vegetation response was larger for the sites that were closer to the core region ofNAMinMexicoand more monitoring is needed to better quantify surface fluxes in this region.  Riparian vegetation classification from airborne laser scanning data with an emphasis on cottonwood trees  Farid, A.UniversityofArizona Rautenkranz, D.UniversityofArizona Goodrich,D.C.SouthwestWatershedResearchCenter Marsh, S.E.UniversityofArizona Sorooshian, S.UniversityofCalifornia,Irvine  Arid and semi-arid regions account for approximately one-third of the land mass of earth. These regions are experiencing continued pressure from population growth in many parts of the world. Water is a critical resource in these regions and is often in short supply. To maintain the economic, social, and ecological viability of these areas it is essential that decision makers and resource managers have a solid scientific basis on which to make watershed based decisions including management of riparian vegetation. Riparian trees use water in proportion to their size, and are especially large users of water in flood plains along rivers in semi-arid environments. It's difficult to measure tree size using traditional ground-based techniques to determine their water use. For this reason new techniques that are more accurate and efficient need to be developed. This study demonstrated that a lidar (light detecting and ranging) system mounted in an airplane can accurately measure features of forest canopies that are related to water use. This includes not only the size, shape and density of leaves on the trees but also the intensity of the light returned from the lidar pulse bouncing back from the tree canopy. Such information is not readily available from other remote sensing methods and was used in this study to classify riparian cottonwood trees of different sizes and ages. The results illustrate the potential of airborne lidar data to differentiate different age classes of cottonwood trees for riparian areas quickly and quantitatively. This information can be used in many forestry, ecological and hydrologic applications that will improve management of hydrologic resources and ecological models.   Automated Geospatial Watershed Assessment Tool (Agwa): Uncertainty Analysis of Common Input Data  Levick, L.R.UniversityofArizona Geurtin, D.P.UniversityofArizona Scoot, S.UniversityofArizona Semmens, D.J.USEPA Goodrich,D.C.SouthwestWatershedResearchCenter  This paper compares simulation results from the Automated Geospatial Watershed Assessment tool (AGWA) (Goodrich et al. 2006) and the KINEROS2 hydrologic model (Woolhiser et al. 1990) for the FAO, STATSGO and SSURGO soils datasets for 10m and 30m digital elevation model (DEM) resolutions on three different sized watersheds.The evaluation of these different soils and topographic data is important to worldwide applications of AGWA/KINEROS2.AGWA was originally designed to work with STATSGO soils.When the SSURGO and FAO soils datasets became available, they were incorporated into AGWA, but simulation results have not been compared using observed data.The results showed that the model performed reasonably well with either DEM and with both SSURGO and STATSGO soils at the smaller watershed scales.Results were poor for all combinations of soils and DEMs for the largest watershed, indicating there may be a problem with the model parameterization.Results for FAO soils were similar to SSURGO and STATSGO for the largest watershed, but showed that both runoff and peak flows were generally underestimated for the smaller watersheds.  Automated Geospatial Watershed Assessment (AGWA): AGIS-based Hydrologic Modeling Tool for Watershed Management and Landscape Assessment  Goodrich,D.C.SouthwestWatershedResearchCenter Scott, S.UniversityofArizona Hernandez, M.UniversityofArizona Burns,I.S.UniversityofArizona Levick, L.R.UniversityofArizona Cate, A.UniversityofArizona Kepner, w.USEPA Semmens, D.USEPA Miller, S. N.UniversityofWyoming Guertin, D. P.UniversityofArizona  When water quantity or water quality is of interest, watersheds are a natural organizing unit in our landscape.Watersheds gather rainfall, infiltrated water, and runoff and typically discharge that water at a stream location or into a body of water such as a lake or estuary.The pathways and processes that affect runoff generation from a watershed result from a complex interaction of the climate, topography, soils, land cover, and land use.Numerous computer models have been developed in to estimate how a watershed produces runoff from rainfall and snowfall.The KINEROS2 and SWAT models are two such examples. These models often require significant data preparation and input to use them.To expedite this task we have developed the AGWA (Automated Geospatial Watershed Assessment hydrologic modeling tool (see:www.tucson.ars.ag.gov/agwa).This tool uses nationally available spatial data sets to setup, run, and display the results from KINEROS2 and SWAT.With AGWA and these watershed models, natural resource managers, engineers, and scientists can estimate runoff and places in the watershed that may be prone to flood damage or water quality problems.These users can also evaluate how conservation measures and changes in land use practices might improve water quality.This paper provides an overview of the AGWA tool with selected examples of its application for a variety of uses.  KINEROS2 - New features and capabilities  Goodrich,D.C.SouthwestWatershedResearchCenter Unkrich, C.SouthwestWatershedResearchCenter Smith, R.Retired ARS Woolhiser, D.Retired ARS  When water quantity or water quality is of interest, watersheds are a natural organizing unit in our landscape.Watersheds gather rainfall, infiltrated water, and runoff and typically discharge that water at a stream location or into a body of water such as a lake or estuary.The pathways and processes that affect runoff generation from a watershed result from a complex interaction of the climate, topography, soils, land cover, and land use.Numerous computer models have been developed to estimate how a watershed produces runoff from rainfall and snowfall.The KINEROS2 model is one such model which can be obtained, with additional documentation and information, fromwww.tucson.ars.ag.gov/kineros.With KINEROS2, natural resource managers, engineers, and scientists can estimate runoff and places in the watershed that may be prone to flood damage or water quality problems.These users can also evaluate how conservation measures and changes in land use practices might improve water quality.This paper provides an overview of the new features and capabilities of KINEROS2.   Toward an automated tool for channel-network characterization, modeling, and assessment  Semmens, D.USEPA Miller, S.N,.UniversityofWyoming Goodrich,D.C.SouthwestWatershedResearchCenter  When water quantity or water quality is of interest, watersheds are a natural organizing unit in our landscape.Watersheds gather rainfall, infiltrated water, and runoff and typically discharge that water at a stream location or into a body of water such as a lake or estuary.The pathways and processes that affect runoff generation from a watershed result from a complex interaction of the climate, topography, soils, land cover, and land use.Much of the water coming out of a watershed is carried through stream channels. Numerous computer models have been developed to estimate how a watershed produces runoff from rainfall and snowfall and how it is carried through channels.Good information on the shape and size of channels is required to address many concerns about runoff, floods and water quality.This information is typically very expensive to collect from ground-based field surveys.A new technology called LIDAR (light detection and ranging) can collect detailed data from airplanes that can be used to describe stream channel shape and size.This paper describes a computer-based tool to aid in acquiring channel information from LIDAR data.A test of this tool was conducted on the USDA-ARS Walnut Gulch Experimental Watershed in southeasternArizona.The LIDAR-based channel data obtained by the tool was compared to ground-based channel measurements with good results.This tool will further assist in the preparation of watershed computer simulation models and running them.  Integrating hydrologic models and spatial data in a distributed internet application  Cate, Jr., A.UniversityofArizona Goodrich,D.C.SouthwestWatershedResearchCenter Guertin, D.P.UniversityofArizona.  DotAGWA is an Internet based application that combines geospatial data and surface water models.Using a web browser like Internet Explorer?, end-users delineate a watershed and define a management plan for the watershed by drawing points, lines and/or polygons on a map.After defining the management plan the user can then create input data sets for one or more surface water simulations.The input data are gathered from various databases built into the application or accessible through the Internet.The input data sets are extracted by using the delineated watershed and once created are passed to the surface water models.Users then run the model(s) and are allowed to download the output data for further analysis and/or review.All of the features built into the web application are hosted on a server that making the application available to anyone with a computer and an Internet connection.   KINEROS2 and the AGWA modeling framework  Semmens, D.USEPA Goodrich,D.C.SouthwestWatershedResearchCenter Unkrich, C.L.SouthwestWatershedResearchCenter Smith, R.E.Retired ARS Woolhiser, D.A.Retired ARS Miller, S.N.UniversityofWyoming  When water quantity or water quality is of interest, watersheds are a natural organizing unit in our landscape.Watersheds gather rainfall, infiltrated water, and runoff and typically discharge that water at a stream location or into a body of water such as a lake or estuary.The pathways and processes that affect runoff generation from a watershed result from a complex interaction of the climate, topography, soils, land cover, and land use.Numerous computer models have been developed to estimate how a watershed produces runoff from rainfall.The KINEROS2 model is one such model which can be obtained, with additional documentation and information, fromwww.tucson.ars.ag.gov/kineros.KINEROS2 and similar models require significant data preparation and input to use them.To expedite this task we have developed the AGWA (Automated Geospatial Watershed Assessment tool (see:www.tucson.ars.ag.gov/agwa).This tool uses nationally available spatial data sets to setup, run, and display the results from KINEROS2.With AGWA and KINEROS2, natural resource managers, engineers, and scientists can readily estimate runoff and places in the watershed that may be prone to flood damage or water quality problems.These users can also evaluate how conservation measures and changes in land use practices might improve water quality.This paper provides an overview of KINEROS2 and AGWA tool with selected examples of its application for a variety of uses.  Discussant comments on upscaling of soil processes to a regional level  Moran, M.S.SouthwestWatershedResearchCenter  The National Academies of Science (NAS) Steering Committee for the Frontiers in Soil Science Research has requested ideas from experts around the world to identify emerging research and application opportunities in soil science.This is partly based on thestrong demand for distributed soil information at the watershed and global scales.There is evidence that this demand could be met by combining satellite imagery with soil models to provide daily, regional soils information for resource managers.This report offers four suggestions to make this happen:1) Support government funding of satellite Earth observation with the goal of providing quantitative products at no charge;2) Invest in disciplines/tools complementary to basic soil science, such as remote sensing and data assimilation; 3) Seek NSF, NASA or private funds to support a concerted effort to model important soil processes at the watershed to global scale; and4) Identify the users of landscape-scale soil information and know users' information requirements.With these actions, a robust system for mapping soil information could be developed and applied to crucial resource management decisions related to soil carbon changes, soil erosion and greenhouse gas fluxes.  Hydrologic modeling uncertainty resulting from land cover misclassification  Miller, S.N.UniversityofWyoming Guertin, D.P.UniversityofArizona Goodrich,D.C.SouthwestWatershedResearchCenter  When water quantity or water quality is of interest, watersheds are a natural organizing unit in our landscape.Watersheds gather rainfall, infiltrated water, and runoff and typically discharge that water at a stream location or into a body of water such as a lake or estuary.The pathways and processes that affect runoff generation from a watershed result from a complex interaction of the climate, topography, soils, land cover, and land use.Land cover data over large watersheds is often obtained from satellite images.The digital signals from these images are classified into different land covers such as forest, grass land, urban, etc. by a variety of computer aided methods.When a satellite image pixel is classified, errors in assigning the pixel to the correct land cover class invariably occur.With additional analyses and information obtained from ground-based checks these errors can be quantified.Since land cover influences watershed runoff, errors in the land cover will impact the simulation of watershed runoff when using a watershed computer model. This study developed a method to access the impacts of land cover mis-classification on modeled watershed runoff.This method was tested on over 40 small to large watersheds in the San Pedro basin in southeasternArizona.Results indicate that as watershed size increases and storm size increases, the impacts of land cover classification errors on runoff decrease.These results provide information on how good a land cover classification must be for watershed runoff modeling.This is also important for water quality as runoff plays a major factor in how sediment, and other chemicals move from the land surface into water bodies.  Planning for increasing irrigation efficiency in Mexico  Cohen, I.S.INIFAP Rodriguez, H.M.INIFAP Heilman, P.SouthwestWatershedResearchCenter Mann, R.S.Retired NRCS  This paper presents in summary fashion a strategy linking researchers, officials and water users of the irrigation district No. 017 in the Comarca Lagunera, a part of Hydrological Region 36 in northernMexico. Members of the Irrigation District participated in building a matrix of problems and possible solutions. The major problem to be addressed is the lack of efficiency in delivering the water, with an estimated 63% of the water lost between the dams and application on irrigated fields. A Decision Support System (Facilitator) was used for making decisions. Solution alternatives have been evaluated by expert opinion. Results have been analyzed considering different orders of importance. According to the findings, the price of water needs to be increased to make the system sustainable. Other important alternatives are to train water users in irrigation matters, increase conveyance efficiency and to provide basic knowledge for agribusiness.  Solving multiobjective problems in the irrigation districts ofMexico  Cohen, I.S.INIFAP Rodriguez, H.M.INIFAP Heilman, P.SouthwestWatershedResearchCenter Cervantes, G.G.INIFAP Valencia, E.D.SouthwestWatershedResearchCenter  This paper presents a detailed explanation of a strategy linking researchers, officials and water users of the irrigation district No. 017 in the Comarca Lagunera, a part of Hydrological Region 36 in northernMexico. The case study describes and applies the Facilitator Decision Support System. Out of the nine alternatives considered by the irrigation district, representatives and users including a baseline (current management), pricing the water resulted in the highest scores for solving the overall problem of the district: increasing irrigation water productivity. Other alternatives that scored well were delivering water to users by volume, rehabilitation of hydraulic infrastructure and training water users. All alternatives scored higher than the current, or baseline, system. Institutional problems may prevent the application of some of the alternatives.  Planeacion multiobjetivo en los distritos de riego enMexico  Cohen, I.S.INIFAP Rodriguez, H.M.INIFAP Heilman, P.SouthwestWatershedResearchCenter Cervantes, G.G.INIFAP Moreno, S.F.INIFAP Inzunza, M.A.INIFAP Avalos, J.E.INIFAP  This paper presents a detailed explanation, in Spanish, of the use of a multiobjective decision support system with a Spanish language interface to address water management in an irrigation district. The problem of agreement among interests in the management of natural resources is complex, with interactions difficult to measure. Watershed users have several objectives that need to be considered when developing a plan to improve water management. A multiobjective decision support system is an appropriate tool to integrate these objectives and assess the desirability of possible actions. A case study using the decision support system called the Facilitator is presented. The Facilitator helps the irrigation district structure the decision making process to consider decision alternatives, order of hierarchy, score functions and linear programming for identifying best decision alternatives for the management of a given problem. For the Irrigation District 017, to help solve the overall problem of irrigation water productivity, the highest ranked alternatives include pricing water, training water users, and delivering water by volume. Out of the eight alternatives analyzed, all alternatives scored  A method for estimating spatial distribution of forage residue and livestock grazing  Duan, Y.UniversityofArizona Heilman, P.SouthwestWatershedResearchCenter Guertin, D.P.UniversityofArizona  Tools to manage spatial information are becoming increasingly widespread. These tools present opportunities to improve management by considering the spatial distribution of resources. Predicting the spatial distribution of forage residue and livestock grazing is important and could benefit from the ability to model forage utilization spatially. However, the lack of understanding of grazing mechanism restricts the interpretation of experimental data. This paper proposes a model of grazing that can be used to derive a grazing function from experimental data. A case study was made for grazing data from the Santa Rita Experimental Ranch in southernArizona. The results support the conclusion that this method can effectively predict the spatial distribution of forage residue and livestock grazing of a pasture based on previous grazing data, predicted forage production, and intended forage utilization level. As detailed spatial measurements of utilization are scarce, the approach could benefit from remotely sensed estimates of utilization.


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