UTILIZATION OF A GEOGRAPHIC INFORMATION SYSTEM TO IDENTIFY THE PRIMARY AQUIFER PROVIDING GROUND WATER TO INDWIDUAL WELLS IN EASTERN ARKANSAS1

ABSTRACT: A Geographic Information System (GIS) was used to develop an automated procedure for identifying the primary aquifers supplying ground water to individual wells in eastern Arkansas. As mandated by state law, water-use data are reported by ground-water withdrawers annually to the Arkansas Soil and Water Conservation Commission, and stored in the Arkansas Site-Specific Water-Use Data System provided and supported by the U.S. Geological Survey. Although most withdrawers are able to provide the amount of water withdrawn and the depth of their wells, very few are able to provide the name of the aquifer from which they withdraw water. GIS software was used to develop an automated procedure for identifying the primary aquifers supplying ground water to individual wells in eastern Arkansas. The software was used to generate a spatial representation of the bottom boundary for the Mississippi River Valley alluvial aquifer (the shallowest aquifer) in eastern Arkansas from well log-data collected by the U.S. Geological Survey. The software was then used to determine the depth of the aquifer bottom at reported well locations to ascertain whether the Mississippi River Valley alluvial aquifer or a deeper aquifer was the primary aquifer providing water to each well. The alluvial aquifer was identified as the primary aquifer for about 23,500 wells.     

HISTORICAL CHANGES IN UPPER MISSISSIPPI RIVER WATER AREAS AND ISLANDS1

ABSTRACT: Periodic surveys of the upper Mississippi River since 1866 and a discharge record of nearly equal length provided an opportunity to learn more about the magnitudes and rates of geomorphic processes at work in large stream systems. Furthermore, geomorphic and hydrologic adjustments could be evaluated in relation to watershed land use changes, small‐scale climate fluctuations, and considerable modifications to the channel and floodplain during the period of record. The present study uses GIS mapping to quantitatively compare historical changes in mapped land and water phenomena in the upper Mississippi River Pool 10, located along southwest Wisconsin's border. Modest channel widening and decreases in island area throughout the study reach during the last century are detectable. Flood magnitudes and frequencies also have varied during this time, and stages and low flow discharges have increased since the 1940s. The latter hydrologic change appears to be closely associated with the reach's geomorphic adjustments. Results are representative of a valley reach where a major tributary contributes a large sand bedload, forming an alluvial fan of considerable size in the floodplain.     

NUTRIENT LOADING ASSESSMENT IN THE ILLINOIS RIVER USING A SYNTHETIC APPROACH1

ABSTRACT: A synthetic relationship is developed between nutrient concentrations and discharge rates at two river gauging sites in the Illinois River Basin. Analysis is performed on data collected by the U.S. Geological Survey (USGS) on nutrients in 1990 through 1997 and 1999 and on discharge rates in 1988 through 1997 and 1999. The Illinois River Basin is in western Arkansas and northeastern Oklahoma and is designated as an Oklahoma Scenic River. Consistently high nutrient concentrations in the river and receiving water bodies conflict with recreational water use, leading to intense stakeholder debate on how best to manage water quality. Results show that the majority of annual phosphorus (P) loading is transported by direct runoff, with high concentrations transported by high discharge rates and low concentrations by low discharge rates. A synthetic relationship is derived and used to generate daily phosphorus concentrations, laying the foundation for analysis of annual loading and evaluation of alternative management practices. Total nitrogen (N) concentration does not have as clear a relationship with discharge. Using a simple regression relationship, annual P loadings are estimated as having a root mean squared error (RMSE) of 39.8 t/yr and 31.9 t/yr and mean absolute percentage errors of 19 percent and 28 percent at Watts and Tahlequah, respectively. P is the limiting nutrient over the full range of discharges. Given that the majority of P is derived from Arkansas, management practices that control P would have the most benefit if applied on the Arkansas side of the border.     

WATER TRANSFERS AND THEIR IMPACTS: LESSONS FROM THREE COLORADO WATER MARKETS1

ABSTRACT: This paper presents an analysis of the effects of different institutional arrangements and economic environments on water markets. Characteristics of water rights transfers in the South Platte Basin of Colorado and transfers of shares of the Northern Colorado Water Conservancy District (NCWCD) are compared to show how different institutional arrangements can affect the types and size distributions of transfers. The characteristics of water rights transfers in the prosperous South Platte are then compared with water rights transfer characteristics in the economically marginal Arkansas River basin of Colorado to identify the effects of different economic environments. Finally, the economic losses from reductions in irrigated acreage resulting from water transfers are estimated for the South Platte and Arkansas and compared with purchase prices by municipalities. Transfers in the South Platte were to new uses in the same basin, while more recent transfers in the Arkansas were to out of basin users. Transfers of South Platte rights and especially NCWCD shares were small and continuous over time, while transfers in the Arkansas were dominated by a few very large transfers. The negative impacts are judged to be more severe in the Arkansas basin than in the South Platte. Purchase prices paid by municipalities substantially exceeded capitalized transitional losses in the selling areas. In the South Platte, gains and losses were in the same basin, while the Arkansas absorbed the losses, with the benefits going to the purchasing basin.     

Pre-instrumental perspectives on Arkansas River cross-watershed flow variability

We present four reconstruction estimates of Arkansas River baseflow and streamflow using a total of 78 tree-ring chronologies for three streamflow gages, geographically spanning the headwaters in Colorado to near the confluence of the Arkansas-Mississippi rivers. The estimates represent different seasonal windows, which are dictated by the shared limiting forcing of precipitation on seasonal tree growth and soil moisture—and subsequently on the variability of Arkansas River discharge. Flow extremes that were higher and lower than what has been observed in the instrumental era are recorded in each of the four reconstructions. Years of concurrent, cross-basin (all sites) low flow appear more frequently during the 20th and 21st Centuries compared to any period since 1600 A.D., however, no significant trend in cross-basin low flow is observed. As the most downstream major tributary of the Mississippi River, the Arkansas River directly influences flood risk in the Lower Mississippi River Valley. Estimates of extreme high flow in downstream reconstructions coincide with specific years of historic flooding documented in New Orleans, Louisiana, just upstream of the Mississippi River Delta. By deduction, Mississippi River flooding in years of low Arkansas River flow imply exceptional flooding contributions from the Upper Mississippi River catchments.     

The Arkansas Valley “Super Ditch”— An Analysis of Potential Economic Impacts1

McMahon, Tyler G. and Mark Griffin Smith, 2012. The Arkansas Valley “Super Ditch”— An Analysis of Potential Economic Impacts. Journal of the American Water Resources Association (JAWRA) 00(0):000‐000. 1‐12. DOI: 10.1111/jawr.12005 Abstract: In Colorado’s Arkansas River basin, urban growth and harsh farming conditions have resulted in water transfers from agricultural to urban uses. Several studies have shown that these transfers have significant secondary economic impacts associated with the removal of irrigated land from production. In response, new methods of sharing water are being developed to allow water transfers that benefit both farm and urban economies, compared with previous permanent transfers that negatively impacted surrounding farm communities. One such project currently under development is the Arkansas Valley “Super Ditch,” which is a rotational crop fallowing plan based on long‐term water leasing designed to provide an annual supply of 25,000 acre‐feet of water (31.6 Mm³). This article analyzes the net benefits of implementing the “Super Ditch” for both the farmers and the surrounding community.     

RELATING TRENDS OF PRINCIPAL COMPONENTS TO TRENDS OF WATER-QUALITY CONSTITUENTS1

ABSTRACT: The seasonal Kendall test is used for detecting water-quality trend or lack of trend for monthly data of 15 water-quality constituents at 15 sampling stations in the Arkansas River, the Neosho River, and the Verdigris River basins. Trends of individual constituents and the trends of the first four principal components for the correlation matrix of water-quality data at each station are determined, and the relationships between the trends of constituents and the trends of principal components are established. Using the principal components not only reduces the high dimensionality of the original data to a few principal components, but also presents an overall picture of water-quality trend of these river basins.     

ALTERNATIVES FOR SALINITY MANAGEMENT IN THE COLORADO RIVER BASIN1

ABSTRACT The Colorado River Basin faces the dilemma of an increasing demand for water while presently struggling with salinity concentrations approaching critical levels for some water uses. Based upon projected development salinity concentrations are predicted to exceed 1200 mg/1 at Imperial Dam by the year 2010. Annual losses to the basin economy associated with increased salinity will exceed $50 million by the year 2010. Although methods of controlling salt discharges are relatively unrefined, certain conclusions, based upon Bayesian statistical methods, can be reached. Five basic alternatives for coping with the problem are presented and evaluated in this paper: (1) do nothing; (2) adopt arbitrary salinity standards; (3) limit development; (4) control salt discharges at a cost equal to the cost of doing nothing, or (5) minimize total costs to the basin. Total costs associated with any given alternative, or the given salinity resulting, are the sum of salinity detriments (cost to users for water of increased salinity plus economic multiplier effects) plus the cost of constructing salt discharge control works. These impacts upon basin economy and Colorado River water quality for each alternative are presented and related to questions of equity which will play a role in arriving at any long-term solution to the Basin's problem.     

IMPACT OF DROUGHT ON QUALITY IN A NEW JERSEY WATER SUPPLY SYSTEM1

ABSTRACT. New Jersey, together with other states in the northeast, was stricken with drought during 1961-66. The effect of this drought was most severe in the northern part of the State. The water quality of the Passaic River, which drains the urban, industrialized northeast, perhaps deteriorated the most among the major drainage systems. This river system is used as a raw-water source by 10 water suppliers. The impact of the drought upon the water supply of the Passaic Valley Water Commission, the most downstream of the basin's suppliers, which supplies an average of about 90 million gallons a day to more than 650,000 persons, is evaluated herein. The drought's impact on the raw-water quality is appraised by the comparison of before-and-after qualities of dissolved solids, dissolved oxygen, biochemical-oxygen demand, turbidity, and hardness. For example, at the worst point during the drought, monthly average dissolved-solids content in the raw water were about 210 percent, hardness, about 167 percent, and biochemical-oxygen demand about 270 percent higher than antecedent values. In general, the study concludes that the drought produced a deterioration in both raw and finished water quality, and is estimated to have increased chemical-treatment costs during the drought by about $650,000.     

Salt Flushing,Salt Storage,and Controls on Selenium and Uranium: A 31‐Year Mass‐Balance Analysis of an Irrigated,Semiarid Valley

Salinity, selenium, and uranium pose water‐quality challenges for the Arkansas River in southeastern Colorado and other rivers that support irrigation in semiarid regions. This study used 31 years of continuous discharge and specific conductance (SC) monitoring data to assess interannual patterns in water quality using mass balance on a 120‐km reach of river. Discrete sampling data were used to link the SC records to salinity, selenium, and uranium. Several important patterns emerged. Consumptive use reduced discharge by a median value of 33% and drove corresponding increases in salinity and uranium concentrations. Increased water availability for irrigation from rainfall and upstream snowpack in 1995–1999 flushed additional salinity and uranium into the river in 1996–2000; average annual total dissolved solids (salinity) concentrations increased 25%, and loads increased 131%. Smaller flushing events have occurred, sometimes lagging an increase in water availability by about one year. The pattern indicates flushing of salts temporarily stored, evaporatively concentrated, or of geologic origin. Mobilization of selenium from the reach was minor compared to salinity and uranium, and net selenium removal from the river was suggested in some years. Several processes related to irrigation could be removing selenium. The results provide context for efforts to improve water quality in the Arkansas River and rivers in other semiarid regions.     

BENEFITS OF ITERATIVE WATER SUPPLY FORECASTING IN THE WASHINGTON,D.C., METROPOLITAN AREA1

The three largest water utilities in the Washington, D.C., metropolitan area (WMA) rely on the Potomac River and its reservoirs for water supply. These utilities have committed to a periodic review of the system's adequacy to meet future demands. In 1990, 1995, 2000, and again in 2004 (for publication in 2005) the utilities requested that the Interstate Commission on the Potomac River Basin (ICPRB) conduct a 20‐year water demand and resource adequacy study to fulfill this need. The selection of the five‐year interval provides multiple benefits. It allows regular updates and incorporation of recent demographic forecasts, and it increases visibility and understanding of the adequacy of the region's water resources. It also provides adequate time to conduct research on the physical system and to incorporate modifications based on this research into subsequent studies. The studies and lessons learned are presented in this case study of the WMA. The work has been a natural outgrowth of a long history of cooperative water supply planning and management among the main WMA water utilities and ICPRB.     

流域水生态系统服务价值评估研究——以黄山市新安江为例

为全面认识新安江水资源价值,本文对河流生态系统的各项服务功能开展了定量评价。本文按照联合国千年评估对生态系统的划分方法(供给、调节、文化与支持4项服务),结合新安江流域水生态系统的特征和结构,建立了15项评估指标体系。以2013年为基准年,对新安江水生态系统服务功能及其生态经济价值进行评价。结果显示:新安江水生态系统服务总价值为73.72亿元,其中,提供产品功能价值9.58亿元、调节功能价值11.77亿元、支持功能价值24.13亿元、文化服务功能价值28.24亿元,分别占总价值的13.0%、16.0%、32.7%、38.3%。新安江单位面积提供的生态系统服务价值为0.41亿元/km~2,高于黄山市单位面积GDP产值0.28亿元/km~2。研究认为,新安江流域水生态系统对支持和保护当地经济发展具有重要作用,研究结果以期为新安江水资源有效管理和区域生态环境保护及水环境补偿提供生态学依据。     

岷江上游流域水电梯级开发的生态环境需水研究

本文通过分析岷江上游水电梯级开发对生态环境的主要影响,确定维持流域生态平衡的最小生态环境需水量测算方法。经测算,岷江上游的生态环境需水量占流域多年平均流量的6%～33%,越靠近源头,生态环境需水量所占比例越大。建议提高岷江上游生态环境需水量所占比例,将生态环境需水占比超过20%的茂县以上河段设为禁止开发区域,取消禁止开发区域内原规划的6级电站。同时在已建电站坝下和各县域出境断面设置生态流量监控断面,确保流域开发的环境生态平衡。     

Phosphorus concentrations, loads, and sources within the Illinois River drainage area, northwest Arkansas, 1997-2008

In the Ozark Highlands and across the United States, effluent phosphorus (P) sources often have a profound impact on water column concentrations and riverine transport. This study evaluated (i) annual P loads at the Illinois River at Arkansas Highway 59 from calendar year 1997 through 2008, (ii) the relative contribution of effluent P sources to annual riverine P transport, (iii) longitudinal gradients in water column P concentrations downstream from several wastewater treatment plant effluent discharges, and (iv) changes in monthly P loads over the last decade. This study showed that annual P loads have ranged from 64,000 kg to over 426,000 kg and that P transport was positively correlated to hydrology (i.e., the amount of water delivered downstream). The relative contribution of P inputs from municipal facilities has decreased from 40% of the annual P load at the Illinois River at Arkansas Highway 59 to < 15% in recent years. Elevated P concentrations during base flow conditions were traced 45 river km upstream to one municipal effluent discharge, but all effluent discharges influenced P concentrations in the receiving streams. Most important, flow-adjusted monthly P loads showed two distinct trends over time. Flow-adjusted loads significantly increased from 1997 through 2002 and significantly decreased from 2002 through 2008. The concentrations and transport of P within the Illinois River drainage area are significantly decreasing from all the watershed management changes that have occurred, and monitoring should continue to determine if this decrease continues at the same rate over the next several years.     

INTEGRATED WATERSHED MANAGEMENT ON THE TRUCKEE RWER IN NEVADA1

ABSTRACT: The Truckee River is a vitally important water source for eastern California and western Nevada. It runs 100 miles from Lake Tahoe to Pyramid Lake in the Nevada desert and serves urban populations in greater Reno-Sparks and agricultural users in three Nevada counties. In the 1980s and 1990s, a number of state and local groups initiated projects which, taken collectively, have accomplished much to improve watershed management on the Truckee River. However, the task of writing a management plan for the entire watershed has not yet been undertaken. Key players in state, federal and local government agencies have instead chosen to focus specific improvement efforts on more manageable, achievable goals. The projects currently underway include a new agreement on reservoir operation, restoration of high priority sub-watersheds, public education and involvement, water conservation education, and water resource planning for the major urban population centers. The approach which has been adopted on the Truckee River continues to evolve as more and more people take an interest in the river's future. The many positive projects underway on the watershed are evaluated in terms of how well they meet the definition of the ambitious water resources strategy, “integrated watershed management.”     

Water Use for Hydraulic Fracturing of Oil and Gas in the South Platte River Basin,Colorado

Water use for oil and gas development (i.e., hydraulic fracturing) is a concern in semiarid basins where water supply is often stressed to meet demands, and oil and gas production can exacerbate the situation. Understanding the impacts of water use for hydraulic fracturing (HF) on water availability in semiarid regions is critical for management and regulatory decisions. In the current work, we quantify water use for HF at several scales — from municipal to state‐wide — using the IHS Enerdeq database for the South Platte Basin. In addition, we estimate produced water (a by‐product of oil and gas production), using data from the Colorado Oil and Gas Conservation Commission to explore reuse scenarios. The South Platte River Basin, located in northeastern Colorado, encompasses the Denver‐Metro area. The basin has one of the most productive oil and gas shale formations in Colorado, with much of the production occurring in Weld County. The basin has experienced higher horizontal drilling rates coupled with an increasing population. Results show water use for horizontal and vertical wells averages 11,000 and 1,000 m³, respectively. Water use for HF in the South Platte Basin totaled 0.63% of the basin's 2014 total water demand. For Weld County, water use for HF was 2.4% of total demand, and for the city of Greeley, water use was 7% of total demand. Produced water totaled 9.4 Mm³ in the basin for 2014, which represents 42% of the total water used for HF.     

Adaptive Water Resource Planning in the South Saskatchewan River Basin: Use of Scenarios of Hydroclimatic Variability and Extremes

The South Saskatchewan River Basin is one of Canada's most threatened watersheds, with water supplies in most subbasins over‐allocated. In 2013, stakeholders representing irrigation districts, the environment, and municipalities collaborated with researchers and consultants to explore opportunities to improve the resiliency of the management of the Oldman and South Saskatchewan River subbasins. Streamflow scenarios for 2025‐2054 were constructed by the novel approach of regressing historical river flows against indices of large‐scale ocean‐atmosphere climate oscillations to derive statistical streamflow models, which were then run using projected climate indices from global climate models. The impacts of some of the most extreme scenarios were simulated using the hydrologic mass‐balance model Operational Analysis and Simulation of Integrated Systems (OASIS). Based on stakeholder observations, the project participants proposed and evaluated potential risk management and adaption strategies, e.g., modifying existing infrastructure, building new infrastructure, changing operations to supplement environmental flows, reducing demand, and sharing supply. The OASIS model was applied interactively at live modeling sessions with stakeholders to explore practical adaptation strategies. Our results, which serve as recommendations for policy makers, showed that forecast‐based rationing together with new expanded storage could dramatically reduce water shortages.     

ESTIMATING NONPOINT SOURCE POLLUTION LOADS WITH A GIS SCREENING MODEL1

ABSTRACT: The St. Johns River Water Management District (SJR-WMD) is using a Geographic Information System (GIS) screening model to estimate annual nonpoint source pollution loads to surface waters and determine nonpoint source pollution problem areas within the SJRWMD. The model is a significant improvement over current practice because it is contained entirely within the district's GIS software, resulting in greater flexibility and efficiency, and useful visualization capabilities. Model inputs consist of five spatial data layers, runoff coefficients, mean runoff concentrations, and stormwater treatment efficiencies. The spatial data layers are: existing land use, future land use, soils, rainfall, and hydrologic boundaries. These data layers are processed using the analytical capabilities of a cell-based GIS. Model output consists of seven spatial data layers: runoff, total nitrogen, total phosphorous, suspended solids, biochemical oxygen demand, lead, and zinc. Model output can be examined visually or summarized numerically by drainage basin. Results are reported for only one of the SJRWMD's ten major drainage basins, the lower St. Johns River basin. The model was created to serve a major planning effort at the SJRWMD; results are being actively used to address nonpoint source pollution problems.     

PATTERN OF GROUND-WATER LEVEL DECLINE IN THE HIGH PLAINS AQUIFER NEBRASKA1

ABSTRACT: Ground-water level decline patterns in parts of Nebraska conform to the circular island concept of Bredehoeft et al. (1982), which indicates how water is derived by wells developed in a circular island. If elongated, the center of the island corresponds to a regional ground-water divide while the shoreline corresponds to a regional river. In both versions, ground-water table elevation is a function of recharge and transmissivity. A dynamic equilibrium exists such that the gradient of the water table will convey all recharge to discharge areas. Withdrawals of ground water result initially in mining, with a new equilibrium attained when pumping equals capture. During early development, capture is an important source of water in discharge areas, while mining is more significant in recharge areas. The pattern observed in many areas shows the greatest ground-water level decline in the vicinity of ground-water divides and the steepest gradient near regional rivers. A similar pattern has been observed adjacent to the Arkansas River in south-central Kansas. Similar decline patterns can be modeled for a hypothetical ground-water basin. This is of major importance to water-resource managers because it dictates that management programs be applied to the entire hydrologic system.     

COMPETING WATER USES IN THE SOUTHWESTERN UNITED STATES: VALUING DROUGHT DAMAGES1

ABSTRACT: Economic benefit functions of water resource use are estimated for all major offstream and instream uses of Colorado River water. Specific benefit estimates are developed for numerous agricultural regions, for municipal uses, and for cooling water in thermal energy generation. Economic benefits of hydropower generation are given, as are those for recreation on Colorado River reservoirs and on one free-flowing reach. Marginal and total benefit estimates for Colorado River water use are provided. The estimates presented here represent a synthesis of previous work, providing in total a comprehensive set of economic demand functions for competing uses of Colorado River water. Non-use values (e.g., benefits of preserving endangered species) are not estimated.