Maximum Streamflow Research Articles

Stochastic Impacts on Farming: II. Seasonally Continuous Probability Distributions

ABSTRACT -MANY farming activities are dependent on seasonal patterns of rainfall, temperature, streamflow, and other climatological variables. In order to establish levels of risk of these variables to aid in planning farm activities a method was developed for calculating continuous seasonal cycles of probabilities for values of the variables. The probabilities are defined by a mathematical surface based on magnitude of event and month of the year. This surface is a modification of the form-free two-dimensional sliding polynomials. Data consisted of one observation per month for each year of record. These data were standardized using a separate monthly variate transform based on the first three moments for each month. The probability surface was evaluated by least-square smoothing of the twelve months simultaneously. Smoothing was constrained by imposition of boundary conditions for extreme magnitude and for maintenance of full seasonal cyclic continuity. The methodology was tested on long-term monthly data that included total rainfall, total EI, daily maximum streamflow and daily minimum streamflow. The seasonal variation of natural risk for each variable was defined quantitatively and presented in a manner to demonstrate how the information in these seasonal patterns supports many existing agricultural practices. Many of these common practices were developed through years of experimentation; however, with the capability to capture more information from historical records the farmer has the opportunity to improve and refine farming operations with known levels of risk..

Alteration of Streamflow Characteristics Following Road Construction in North Central Idaho

Effects of logging access roads on seven streamflow variables were monitored on six forested headwater watersheds in north central Idaho. The streamflow variables were annual maximum streamflow, date of maximum streamflow, annual minimum streamflow, annual water yield, and streamflow equaled or exceeded 5% of the year, 25% of the year, and 75% of the year. The watersheds, ranging in area from 28.3 to 147.7 ha, had less than 5% of their area in roads. Two statistically significant (α = 0.05) changes occurred following road construction: an increase in the 25% exceedance flows in one watershed and a decrease in the 5% exceedance flows in another watershed. No significant changes were detected in other flow parameters on any of the watersheds. The results indicate that the hydrologic behavior of small forested watersheds may be altered when only a small area is disturbed by roads.

Predicting Solute Yields in the Natural Waters of a Subalpine System in Alberta, Canada

An intensive sampling of the natural waters originating from a subalpine watershed was carried out during 1971 and 1972. The information obtained was utilized in regression models to estimate daily outputs of the main constituents (Ca++, Mg++, and HCO3-) and other constituents (Na+, S04--, and SiO2). Despite the small size of the area (9.40 km2), the yields of the geochemical constituents were large; the sum of constituents ranged from 12.4 to 409.2 t km2 yr-1. The derived equations were independently tested for their predictions for the years 1973 and 1974, and showed their validity in such estimations. The statistical relationships for estimating solute loads provided geochemical information on the subalpine system for different times during the year. The rate of increase in solute yields for unit increase in streamflow was maximum for HCO,- and Ca++, moderate for S04--, and Mg++, and minimum for SiO2, Na+, and K+. Maximum solute loads were transported during the months having maximum streamflows (May, June, July).

Morphometry and floods in small drainage basins subject to diverse hydrogeomorphic controls

Morphometric parameters such as drainage density, stream magnitude, and relief ratio are practical measures of flood potential in small (<100 mi2) drainage basins. Stereoscopic interpretation of low‐altitude aerial photographs provides the most accurate maps of basins for generating these parameters. Field surveys of a high‐density limestone basin in central Texas show that 1:24,000 scale topographic maps accurately portray the efficient stream channel system but fail to reveal numerous small gullies that may form portions of hillslope hydrologic systems. Flood potential in drainage basins can be defined by a regional index computed as the standard deviations of the logarithms of the annual maximum streamflows. High potential basins tend toward greater relief, greater drainage density, and thus greater ruggedness numbers than low–flash flood potential watersheds. For a given number of first‐order channels (basin magnitude), flash flood regions have greater ruggedness numbers, indicating higher drainage densities combined with steep hillslopes and stream channel gradients. Transient controls on flood response, such as differences between local rainstorm intensities, appear to be the major influences on hydrographs in areas of moderate dissection and relief. Morphometric parameters for low‐potential flash flood regions )Indiana and the Appalachian Plateau( are better estimators of frequent low‐magnitude runoff events (mean annual flood), while the same parameters correlate better with the maximum flood of record in high‐flood potential regions (central Texas, southern California, and north central Utah).

Future Power Development in the Middle West

Abstract In this paper the author outlines a system in which it is proposed that the fairly efficient steam power plants in the 100-odd cities of over 25,000 population in the 14 middle-western states be interconnected, not by heavy high-voltage lines, but by lines running from each which will pick up the small-town and village load to the point where its next larger neighbor will take its share; hydroelectric plants are to be installed on the streams near the towns and villages, each with a small pondage; the steam stations are to carry the steady continuous load above the maximum stream flow, the hydroelectric plants automatically coming on to carry the peaks. On the off-peak period the hydroelectric plants will restore the pondage and carry local load. The quickness with which the latter can get on the line (12 to 30 seconds) will enable the steam stations always to work at maximum efficiency. The advantages of the system are pointed out in the paper, as well as the procedure necessary to bring about its development.