UNCERTAINTIES IN ESTIMATING THE WATER BALANCE OF LAKES1

ABSTRACT: Evaluation of hydrologic methodology used in a number of water balance studies of lakes in the United States shows that most of these studies calculate one or more terms of the budget as the residual. A literature review was made of studies in which the primary purpose was error analysis of hydrologic measurement and interpretation. Estimates of precipitation can have a wide range of error, depending on the gage placement, gage spacing, and areal averaging technique. Errors in measurement of individual storms can be as high as 75 percent. Errors in short term averages are commonly in the 15-30 percent range, but decrease to about 5 percent or less for annual estimates. Errors in estimates of evaporation can also vary widely depending on instrumentation and methodology. The energy budget is the most accurate method of calculating evaporation; errors are in the 10–15 percent range. If pans are used that are located a distance from the lake of interest, errors can be considerable. Annual pan-to-lake coefficients should not be used for monthly estimates of evaporation because they differ from the commonly used coefficient of 0.7 by more than 100 percent. Errors in estimates of stream discharge are often considered to be within 5 percent. If the measuring section, type of flow profile, and other considerations, such as stage discharge relationship, are less than ideal errors in estimates of stream discharge can be considerably greater than 5 percent. Errors in estimating overland (nonchannelized) flow have not been evaluated, and in most lake studies this component is not mentioned. Comparison of several lake water balances in which the risdual consists solely of errors in measurement, shows that such a residual, if interpreted as ground water, can differ from an independent estimate of ground water by more than 100 percent.     

THE VRANA LAKE HYDROLOGY (ISLAND OF CRES - CROATIA)1

ABSTRACT: The Vrana Lake on the island of Cres in the Adriatic Sea represents a specific phenomenon of karst hydrology. The island of Cres covers an area of 404.3 km² with an average volume of 220 × 10⁶ m³ of fresh water in the lake. The island has an average rainfall of 1,063 mm, with a Mediterranean climate. The lake has a bottom reaching a depth of 62 m below mean sea level. The average water level is 14 m above mean sea level. The most probable theories on the origin of the lake and its hycirologic-hydrogeologic functioning state that it is a flooded poije in karst. The water budget method was used to define the lake catchments area at approximately 25 km². During the last six years, there has been drastic decrease of about 3 m in the lake's water level. This phenomenon was analyzed and it was calculated that 53 percent of the water-level decline was caused by water discharges from the lake to satisfy water supply demands, and 47 percent was due to a period of low precipitation during the analyzed period.     

DENSITY CURRENT INTRUSIONS IN AN ICE-COVERED URBAN LAKE1

ABSTRACT: Evidence is presented that snowmelt runoff from an urban watershed can produce density current intrusions (underflows) in a lake. Several episodes of density current intrusions are documented. Water temperatures and salinities measured near the bottom of a 10 m deep Minneapolis lake during the late winter warming periods in 1989, 1990, 1991, and 1995 show significant rapid changes which are correlated with observed higher air temperatures and snowmelt runoff. The snowmelt runoff entering this particular lake (Ryan Lake) has increased electrical conductivity, salinity, and density. The source of the salinity is the salt spread on urban streets in the winter. Heating of littoral waters in spring may also contribute to the occurrence of the sinking flows, but is clearly not the only cause.     

COORDINATION OF PUBLIC AND PRIVATE AC A CASE STUDY OF LAKE RESTORATION1

ABSTRACT: The potential for joint public and private action for lake restoration is examined using Lake Apopka, Florida, as a case study. Initial calculations indicate that private incentives alone are inadequate to attract investment in a facility to grow and harvest water hyacinths for conversion to methane gas. However, the private externality of water quality improvement associated with harvesting water hyacinths provides a key linkage between the public's water quality objectives and the private gas producer's actions. In order to establish the potential basis for negotiation, the public's willingness-to-pay for environmental services associated with improved water quality is estimated and compared with the estimated subsidy required to induce private action. A conceptual framework is then presented for coordinating actions between private firms and public water management agencies in order to internalize the private externality of water quality improvement while simultaneously achieving the public and private objectives. Results indicate that the subsidization of water hyacinth production and harvesting compares favorably with alternative means of enhancing the water quality of Lake Apopka.     

REASONABLY FULL HYDROLOGIC DEVELOPMENT OF RESERVOIR SITES1

The size of multipurpose reservoir development is usually determined by an economic analysis of reservoir capabilities and the present and projected water resources needs which can be satisfied. This analysis is referred to as project formulation, wherein optimum conditions are sought. In responding to multiple objectives, i.e., national economic development, regional development and environmental quality, which are being considered in river basin planning in recent years, reservoirs should provide for reasonably full hydrologic development. Additional storage will be needed to provide opportunities for economic development, as well as meet unexpected development. Also, it provides more flow regulation capability for quality of environment considerations. An analysis has been made on twelve reservoir sites in the New York State portion of the Susquehanna River Basin to determine the so-called “reasonably full hydrologic development of reservoir sites.” Hydrologic, economic, environmental and physical characteristics of the sites are taken into consideration. For normal conditions, it can be concluded that a yield equivalent to about 80 percent of the average discharge (runoff) can be considered as reasonably full hydrologic development for reservoir sites in the Susquehanna River Basin in New York. The same technique can be applied elsewhere to determine reasonably full hydrologic development of reservoir sites.     

REVIEW OF LAKE RESTORATION PROCEDURES1

ABSTRACT Relevant information on the restoration of lakes is presented. The restoration procedures considered are applicable to the water, the bottom sediments, and aquatic plant improvement. A summary of thirteen (13) suggested methods of restoration are reviewed.     

WATER BALANCE OF PACIFIC ATOLLS1

ABSTRACT: This study presents an estimate of water balance components for Pacific atolls under average dimatological conditions. Figures show annual potential evapotranspiration, annual recharge for rain-fed and aquifer-fed vegetated areas, and the number of months that potential evapotranspiration exceeds actual evapotranspiration (indicating water stress) under average conditions. The method relies on the assumption that small islands have minimal influence on cloudiness and precipitation. The potential evapotranspiration is computed using the equilibrium evaporation concept, and estimates of monthly soil water storage and recharge follow Thornthwaite's bookkeeping method. Gradients in potential evapotranspiration run primarily north-south, though for the equatorial zone potential evapotranspiration declines from east to west, opposing the trend in rainfall. Recharge estimates range from 250 mm in the central Tuamotu Archipelago and zero in eastern Kiribati to over 2000 mm per year in the southern Caroline Islands (U.S. Trust Territory) and Solomon Islands. The sensitivity of the model to intra-month rainfall variability and a range of available soil moisture values is discussed.     

A SENSITIVITY ANALYSIS OF THE PALMER HYDROLOGIC DROUGHT INDEX1

ABSTRACT: The sensitivity of the Palmer Hydrologic Drought Index to departures from average temperature and precipitation conditions is examined. A time series of zero index values was calculated and then one monthly temperature or precipitation value was perturbed. The resulting time series shows the effects on the index of one anomalous value. Independent series were calculated for temperature anomalies of plus and minus 1, 3, 5, and 10F and for precipitation anomalies of 25, 50, 75, 125, 150, and 200 percent of normal for each calendar month for Colorado, Indiana, Nevada, New York, Oklahoma, South Carolina, South Dakota, Washington, and Wisconsin. Analysis of the time series showed that the period of time required for the index to reflect actual rather than artificial initial conditions could be more than four years. It was also found that the effects of temperature anomalies are insignificant compared to the effects of precipitation anomalies. In some cases, one anomalous precipitation value could result in established wet or dry spells that last for up to two years. Although not examined in detail, the time series suggest that distributions of index values may be asymmetrical and possibly bimodal.     

THE IMPACT OF STOCKWATERING PONDS (STOCKPONDS) ON RUNOFF FROM LARGE ARIZONA WATERSHEDS1

ABSTRACT: Major water rights adjudications involving the Little Colorado River Basin and Gila River Basin are presently underway within Arizona. Water resource managers are faced with the prospect of evaluating and regulating tens of thousands of water diversions and uses. Stockponds comprise a large percentage of the total number of water diversions within these basins. Water balance studies conducted on the Little Colorado River watershed above Lyman Lake and on the Gila River watershed above Solomon, Arizona, indicate that the impact of stockponds on the water available to downstream users is insignificant when compared to total watershed production. Considering that there are an estimated 25,000 stockponds in the Gila River basin alone, rigorous case-by-case investigations and stringent regulation of individual stockponds may be impractical and unwarranted. Therefore, stock-pond claims within the context of the general adjudication process may be effectively handled by partial summary judgment, thereby allowing the court to concentrate on major water users and water rights issues.     

DEFINING REGIONAL POPULATIONS OF LAKES FOR THE ASSESSMENT OF SURFACE WATER QUALITY1

ABSTRACT: Topographic maps are commonly used to define populations of lakes in regional surveys of surface water quality. To illustrate the effect of different maps on that process, we compared the lakes represented on the 1:250,000-scale maps used for the Northeast Region of the Eastern Lake Survey—Phase I (ELS-I) to the lakes on a sample of large-scale maps (1:24,000 or 1:62,500). Lake areas at or near the lower limit of representation delimited “smallest-lake” values for the compared 1:250,000-scale maps. The regional median for these values was 4.5 hectares (ha) and ranged from 0.6 to 24.8 ha. Lake representation is influenced by cartographic limitations such as map scale, age, and complexity as well as the inherent variability of waterbodies (e.g., water level fluctuations or the creation of reservoirs, beaver impoundments, and oxbows). The total number of lakes on large-scale maps increased markedly as lake area decreased. Approximately 15,700 of the estimated 29,000 lakes in the EPA's Northeast Region were 1 to 4 ha in area. Because maps affect the size distribution of lakes included in a regional survey and because lake areas are thought to modify lake chemistry, maps ultimately affect the estimates of regional surface water quality.     

HYDROLOGIC EFFECTS OF CLIMATE CHANGE IN THE DELAWARE RWER BASIN1

ABSTRACT: The Thornthwaite water balance and combinations of temperature and precipitation changes representing climate change were used to estimate changes in seasonal soil-moisture and runoff in the Delaware River basin. Winter warming may cause a greater proportion of precipitation in the northern part of the basin to fall as rain, which may increase winter runoff and decrease spring and summer runoff. Estimates of total annual runoff indicate that a 5 percent increase in precipitation would be needed to counteract runoff decreases resulting from a warming of 2°C; a 15 percent increase for a warming of 4°C. A warming of 2° to 4°C, without precipitation increases, may cause a 9 to 25 percent decrease in runoff. The general circulation model derived changes in annual runoff ranged from ?39 to +9 percent. Results generally agree with those obtained in studies elsewhere. The changes in runoff agree in direction but differ in magnitude. In this humid temperate climate, where precipitation is evenly distributed over the year, decreases in snow accumulation in the northern part of the basin and increases in evapotranspiration throughout the basin could change the timing of runoff and significantly reduce total annual water availability unless precipitation were to increase concurrently.     

DEVELOPMENT AND VERIFICATION OF A WATER BALANCE MODEL FOR SUBSURFACE DRAINAGE DESIGN1

ABSTRACT: A water balance model was developed to predict daily water table depths in some corn fields with or without subsurface drainage systems, using pertinent soil and water properties and weather data. The model outputs were compared with the recorded data of observed water table depths. Some statistical parameters such as the mean, standard deviation, the coefficient of correlation, the sum of the squares of deviations, and a nonparametric statistical test were used to study the extent of agreement between the observed and the predicted water table depths. No significant difference was found between the distributions of the observed and the predicted water table depths at the 99% confidence level. The study was conducted on some sand and clay soils of the Ottawa-St. Lawrence Lowlands region in Canada where there is a cool, moist climate and poor natural drainage.     

MULTIVARIATE TREND TESTING OF LAKE WATER QUALITY1

ABSTRACT: Multivariate methods of trend analysis offer the potential for higher power in detecting gradual water quality changes as compared to multiple applications of univariate tests. Simulation experiments were used to investigate the power advantages of multivariate methods for both linear model and Mann-Kendall based approaches. The experiments focused on quarterly observations of three water quality variables with no serial correlation and with several different intervariable correlation structures. The multivariate methods were generally more powerful than the univariate methods, offering the greatest advantage in situations where water quality variables were positively correlated with trends in opposing directions. For illustration, both the univariate and multivariate versions of the Mann-Kendall based tests were applied to case study data from several lakes in Maine and New York which have been sampled as part of EPA's long term monitoring study of acid precipitation effects.     

AN ANALYSIS OF PLAYA LAKE WATER UTILIZATION ON THE TEXAS HIGH PLAINS1

ABSTRACT: This paper examines the spatial, temporal and legal aspects of playa lake water utilization on the semi-arid Texas High Plains. These small basins of interior drainage collect and briefly hold an estimated two to three million acre-feet of runoff water annually, representing from one-fourth to one-third the quantity of groundwater pumped from the dwindling Ogallala aquifer. Once considered a detriment to farming operations, there is now increased interest in using playa water more effectively. At present direct pumping is the chief method of utilization, and modification of lake bottoms to concentrate runoff and reduce evaporation is the most widespread conservation practice. The use of playa water for groundwater reacharge is hampered by as yet unsolved technical problems. For many years the question of ownership of playa water remained unsettled. The Texas Water Rights Commission now classes it as diffused surface water, which under Texas law may be used by the landowner, though some legal problems remain. For play lakes to be effectively integrated into the regional water resource it becomes imperative that all present and prospective water utilization problems be identified and resolved.     

EFFECTS OF LAKE MICHIGAN DIVERSION ON THE WATER CHEMISTRY OF THE ILLINOIS WATERWAY1

: Chemical quality characteristics of the Illinois waterway covering a stretch of 270 river miles were monitored at approximately 10 mile intervals, during the period June to September of 1978 and 1979. A statistical method was used to define the interstation relationships for the chemical parameters. These mathematical models were used to predict the effects of Lake Michigan diversion. The mineral content of the mixed flow resulting from increased diversions are not likely to be altered drastically.     

MATERIALS INPUT OF LAKE CHAMPLAIN: A SYNOPTIC APPRAISAL1

ABSTRACT: The complex morphometry of Lake Champlain requires that detailed, regional studies be made, and the results integrated, to yield total lake conditions. Using specific conductance measurements, and values of total dissolved solids calculated from them, we present an approach to assessing the materials budget of the lake. The sampling program involved inventorying all 319 tributaries, determining the watershed area for each, and dividing the Champlain basin into appropriate hydrographic regions. Data were obtained from samples collected from 41 selected streams (representing 97.5% of the annual water input), sampling occurring in all seasons of the year since 1970. Results indicate that over one million metric tonnes of total dissolved solids enter Lake Champlain annually, about two-thirds (63%) from the eastern (Vermont) portion and almost one-fourth (22%) from the western (New York) part of the drainage basin, the remainder (15%) entering from the south end. Of the total quantity added annually, 17.4% is retained in the lake, indicating that a solids build-up is occurring, at a significant rate. We suggest that specific conductance, and therefore total dissolved solids, be utilized as a convenient indicator of water quality conditions, and results applied to permit more efficient watershed management.     

POSSIBLE DIVERSION OF MISSISSIPPI RIVER WATER TO TEXAS AND NEW MEXICO1

ABSTRACT .A summary is presented of remarks made at a conference held at Louisiana Tech University on the possibility of diverting some of the Mississippi River water to Texas and New Mexico. The Texas Water Plan which has initiated the diversion possibility is discussed and particular reference is made to the activities of the federal and state agencies directly responsible for determining various aspects of the diversion study. These agencies include the Texas Water Development Board, Texas Water Quality Board, Louisiana Department of Public Works, State Engineer's Office of New Mexico, Mississippi River Commission, and the Bureau of Reclamation.     

USING HEAT CAPACITY MAPPING MISSION (HCMM) DATA TO ASSESS LAKE WATER QUALITY1

ABSTRACT A water quality investigation on Utah Lake was conducted during the same time period that the Heat Capacity Mapping Mission (HCMM) satellite was collecting thermal infrared and reflectivity data. Relationships were established and evaluated among HCMM data and lake water quality parameters. Although remotely sensed reflective data have been previously utilized, this study was unique in that thermal emitted data were also correlated to algae concentrations and other indicators. Standard statistical evaluations were made along with utilization of color graphics techniques to identify and plot relationships. The emitted thermal energy was found to have high positive correlations with net algal concentrations and with the predominant species, Aphanizomenon flos-aquae, a blue-green alga. No continuous correlation was found for a less abundant red pigment phytoplankton, Ceratium hirundinella. Similar trends, though for negative correlations, were shown for reflectivity data and algal concentrations throughout the spring and summer. Coincidence of areas of warmer emitted energy and darker relfected energy on colorgraphics displays clearly indicate lake areas of high algal concentrations. Night thermal data displayed a strong negative correlation with algal concentration, opposite to day thermal data. Color graphics of warmer day emitted energy and cooler night emitted energy further verify areas of high algal concentrations.     

THE ECONOMIC FEASIBILITY OF DUAL PURPOSE NUCLEAR DESALINATION OF GROUND WATER1

ABSTRACT: The economic feasibility of a large scale dual purpose (desalting water and power production) facility were evaluated. Although a site in the Tularosa basin of southern New Mexico was chosen as a case study for this analysis, it is believed that the approach and consequential results would be applicable to alternative sites in the Southwest. The basic project evaluated included: a) a ground water well field; b) a dual purpose, nuclear, desalination plant; c) a mineral recovery plant; and d) a reservoir for recreation and irrigation storage. Principle project outputs included electrical power, minerals, recreation, and water for either irrigated agricultural production or export to an adjoining river basin. Two alternative project designs were developed for detailed analysis. The first alternative encompassed all major project components. The results, in discounted net values used to assess the feasibility of the project, were essentially negative; that is, values were less than zero for full scale development. The net benefits ranged from $-986.57 million at a 5 percent discount rate, to $-1,137.528 million at a discount rate of 10 percent. In the second alternative, exportation of the desalted water from the Tularosa basin to two adjacent rivers was analyzed with somewhat better net benefits, ranging from $-382,527 million to $-478,612 million at the 5 and 10 percent discount rates.     

HYDROLOGIC IMPACTS OF A LARGE-SCALE MOUNTAIN PINE BEETLE (DENDROCTONUS PONDEROSAE HOPKINS) EPIDEMIC1

The Jack Creek watershed, a 133 km² (51.5 mi²) drainage in southwestern Montana, was impacted by a mountain pine beetle (Dendroctonus ponderosae Hopkins) epidemic in 1975–1977 which killed an estimated 35 percent of its total timber. Analyses of USGS streamflow data for four years prior to and five years after mortality suggest a 15 percent post-epidemic increase in annual water yield, a two-to three-week advance in the annual hydrograph, a 10 percent increase in low flows and little increase of peak runoff.