WRRC Technical Reports

Permanent URI for this collectionhttps://hdl.handle.net/10125/1680

Browse

Now showing 1 - 20 of 163

WRRCTR No.41 Electrodialysis for Desalting Hawaiian Brackish Ground Water: A Field Study
(Water Resources Research Center, University of Hawaii at Manoa, 1970-07) Lau, L. Stephen; Chou, James C.S.
A field study was made to evaluate the applicability and problems of desalting brackish ground water from basaltic and reef limestone aquifers in Honolulu, Hawaii with the electrodialysis process. The three-week study indicated that the brackish water at both sites was upgraded to potable quality and the rejection of ionized salts was above 80 percent. No pretreatment was necessary. Both the average production and rejection rates were about 420 gpd. An economic evaluation was not determinable from the short-term results.
WRRCTR No.42 Instantaneous Unit Hydrograph Analysis of Hawaiian Small Watersheds
(Water Resources Research Center, University of Hawaii at Manoa, 1970-08) Wang, Ru-Yih; Wu, I-Pai; Lau, L. Stephen
The analysis of about 240 flood hydrographs of 29 small watersheds on the island of Oahu, Hawaii, shows some unique hydrologic characteristics. A typical Hawaiian small watershed has a small area, flash peak, short time to peak, and small recession constant. Most of the hydrographs have the typical shape of a steep triangle. Based on statistical analysis of the observed flood hydrographs, a linear relationship has been found between peak discharge and the volume of runoff for each watershed. Because of the similar shape of the semi-dimensionless hydrographs, a unit-hydrograph with uncertain duration can be developed for each small watershed. The duration of such unit hydrographs can be determined by using the S-hydrograph technique with the equilibrium discharge as a criterion and the trial-and-error method utilizing a digital computer. The durations of the unit hydrograph, or the effective rainfall durations for Hawaiian small watersheds, were found to range from 5 minutes ot one hour. A good correlation has been found to exist between effective rainfall duration and the watershed area. Such a short duration unit hydrograph can be used to develop an instantaneous unit hydrograph by using Nash's conceptual model and the method of moments, assuming the effective rainfall is uniformly distributed with respect to time and space. The instantaneous unit hydrgraph for each watershed can then be solved by a computer. The two instantaneous unit hydrograph parameters, Gamma function argument, N, and reservoir storage constant, K, were found to correlate with areas of small watersheds. The instantaneous unit hydrograph of a given ungaged area can be determined by knowing the area of the watershed. The flood hydrograph with a given duration can also be solved by applying the incomplete Gamma function. The superposition characteristics of a linear model can be applied for hydrograph analysis of Hawaiian small watersheds. Hence, the design discharge with certain recurrence years for different engineering purposes can be directly multiplied with the design runoff, which may be obtained with the reference of the rainfall depth-frequency-duration charts and soil conditions for certain areas. A hydrograph study using an instantaneous unit hydrograph provides a good approach for hydrologic research since the short duration of effective rainfall is close to the duration caused by an instantaneous burst of rainfall. The study also synthesizes the parametric hydrograph which simplifies hydrograph analysis.
WRRCTR No.44 Identification of Irrigation Return Water in the Sub-surface, Phase III: Kahuku, Oahu and Kahului and Lahaina, Maui
(Water Resources Research Center, University of Hawaii at Manoa, 1970-12) Tenorio, Pedro A.; Young, Reginald H.F.; Burbank, Nathan C Jr.; Lau, L. Stephen
This study continued the joint research effort undertaken by the Water Resources Research Center and the Honolulu Board of Water Supply in 1967 to investigate the physical and chemical characteristics of irrigation return water. Initial work concentrated on the Pearl Harbor-Waipahu area of Oahu. The phases reported herein included both Kahuku Plantation on Oahu and the sugar cane cultivation areas of central and West Maui (Pioneer Mill Co. and Hawaiian Commercail and Sugar Co.). Composite well, spring, and stream samples were taken and analyzed in the laboratory for the following constituents: bicarbonate, calcium, magnesium, phosphate, silica, boron, chloride, nitrate, sodium, potassium, bromide, flouride, sulfate, and total hardness. On the basis of increased index constituents over uncontaminated ground-water sources used to identify the presence of irrigation return water, it is evident, as previously concluded by Visher and Mink (1964), such irrigation return water, is definitely present in the basal water bodies underlying the three study areas. Considerable increases in the nitrate and sulfate indices, especially, and in the bicarbonate and silica indices, as shown by various methods of interpretation of water quality data obtained over a period of approximately two years or exceeding one complete cycle of plainting and harvesting of sugarcane, verify the strong influence of irrigation agricultural practices in altering the overall quality of the basal water sources in the three areas. The basal water quality of the HC&S aquifer is most affected regionally, as well as locally, by the prevailing agricultural practices. The deterioration of the water is dues in part to fertilization and to a greater exten to heavy pumping and recycling of the basal water. Water quality in the Pioneer Mill area parallels that of HC&S, although on a regional basis, the basal water quality, unlike that of the Pioneer Mill area, is not as deteriorated. Local effects of pumping are also especially noticeable in the Pioneer Mill area. Ground-water quality in the Kahuku area shows the obvious presence of irrigation return water indices, but, unlike the two plantations on Maui, the magnitude of the increases relative to uncontaminated water sources is considerably smaller. The effect of fertilization on Kahuku may be considered to be a principal factor in the regional distribution of index constituents with a relatively uniform nitrate distribution throughout. Local effects of pumping are quite pronounced and influence overall increases of indices, indicating that where heavy pumping takes place for irrigation, the increase in index constituents are correspondingly greater.
WRRCTR No. 45 Density Logs from Underground Gravity Surveys in Hawaii
(Water Resources Research Center, University of Hawaii at Manoa, 1971-02) Huber, Richie D.; Adams, William M.
The gravity method has been applied in three wells in Hawaii to estimate density and porosity logs. The wells are the Schofield shaft on the island of Oahu, the Kihei #3 shaft on the island of Maui and the Pahala shaft on the island of Hawaii. The method determines the "averaged" density and porosity values for Hawaiian rocks. On Oahu, the density at depth is 2.4 gm/cc and the corresponding porosity is 18 percent. For Maui, the density averages about 2.4 gm/cc and porosity at 17 percent. The Hawaii shaft shows a lower density of 2.0 gm/cc with a correspondingly higher porosity of 27 percent. All these values are based on a grain density of 2.9 gm/cc.
WRRCTR No. 4 Development of Deep Monitoring Stations in the Pearl Harbor Ground Water Area, Oahu
(Water Resources Research Center, University of Hawaii at Manoa, 1967-03) Cox, Doak C.; Lao, Chester
Two deep wells, one at Puuloa and the other at Ewa Beach in the Pearl Harbor area were drilled through the thick sedimentary gap into Koolau basalt, and have been readied for multiple-zone recording of water levels and water quality. Plastic pipes were lowered into the wells to selected depths determined by core composition and electric well logs. Gravel and beach sand were used selectively to backfill the wells. Thirteen sampling tubes were installed in the Puuloa well, and seven sampling points were placed in the main well at Ewa Beach. A shallow auxiliary well was also drilled at Ewa Beach. Evidence from preliminary development of the deep aquifer at Ewa Beach indicates the possible existence of a thin layer of fresher water floating on water of nearly seawater composition. Water levels are being monitored in this aquifer and show a tidal efficiency of approximately 15 percent. The smaller sampling tubes are being developed at both sites.
WRRCTR No. 3 Dynamic and Static Studies of Seawater Intrusion
(Water Resources Research Center, University of Hawaii at Manoa, 1967-02) Lau, L. Stephen
A theoretical equation was adapted and modified for a water-table aquifer to relate freshwater flow to the sea, geometry of the fresh water-sea water interface, and aquifer characteristics under dynamic equilibrium. Verification was obtained in laboratory experiments conducted in a hydraulic sand model. Other laboratory experiments revealed special flow patterns in the transitional zone of the freshwater-seawater interface. The extent and the vertical density gradient of the brackish water in the transitional zone were examined for their effects on modifying the conventional Ghyben-Herzberg Patio. Groundwater data collected from a deep well on Oahu, Hawaii was discussed as an illustration.
WRRCTR No.2 Infiltration and Percolation of Sewage Through Oahu Soils in Simulated Cesspool Lysimeters
(Water Resources Research Center, University of Hawaii at Manoa, 1966-08) Koizumi, Melvin K.; Burbank, Nathan C.; Lau, L. Stephen
This study investigated conditions contributing to cesspool failure and followed selected parameters to measure the degree of treatment afforded sewage in cesspool disposal. This laboratory study utilized bench scale soil lysimeters and two basic soil types: the Wahiawa Low Humic Latosol and the Lolekaa Humic Latosol. The soils were specimens from areas of potential urban development within known ground water recharge zones. The results of this experiment indicate that unless further degradation of the effluent is effected by the soil mass, the incomplete degradation of the sewage makes it a definite hazard to ground water sources. This study presents soil-effluent inter-reaction at a one-foot depth. No conclusive evidence exists to substantiate any further degradation of the effluent by the soil at greater depths to the required U.S. Drinking Water Standards of 45 mg/l of nitrates.
WRRCTR No.81 A Dynamic Water and Related Land Resource Planning Model: It's Application to an Hawaiian Small Water System
(Water Resources Research Center, University of Hawaii at Manoa, 1974-07) Liang, Tung; Huang, Wen-Yuan; Wu, I-Pai
Planning an optimal system of activities for generating economic goods and services within an existing natural resource capacity is a difficult problem to solve. A mathematical programming model with the capacity to check multiple resource demand and supply compatibility over many time periods was developed as a solution to this type of problem. The characteristics of natural resource supply and the demand of activities were utilized to reduce the number of time periods and to minimize the loss of the dynamic reality of the problem. Reduction in the number of time periods extended the capability of the model in solving complex resource planning problems without oversimplification. The advance in computer memory size and speed has made multi-period mathematical programming models a practical and desirable tool in planning optimal production scheduling and optimal allocation of resources. However, the construction of a large constraint matrix generated by multi-period models remains an obstacle to the use of multi-period linear programming (LP) models. A matrix generator capable of dividing time span according to resource characteristics and TBM-MPS output compatible matrix for LP optimization was developed.
WRRCTR No.79 Water Recycling of Sewage Effluent by Irrigation: A Field Study on Oahu: Second Progress Report for July 1972 to July 1973
(Water Resources Research Center, University of Hawaii at Manoa, 1974-11) Lau, L. Stephen; Ekern, Paul C.; Loh, Philip C.S.; Young, Reginald H.F.; Burbank, Nathan C Jr.; Dugan, Gordon L.
An investigation of recycling sewage effluent by irrigation under Hawaiian conditions is being conducted in pilot field studies near Mililani Town in central Oahu under the sponsorship of the Board of Water Supply and the Division of Sewers, City and County of Honolulu. The primary objective of the project is to determine the feasibility of wastewater application to the soil and its probable effects on the quality of groundwater in terms of dissolved materials and viruses. Corollary objectives are to ascertain its effects on sugarcane yield and grasslands.
WRRCTR No.82 Fate of Heavy Metals in the Sewage Treatment Process
(Water Resources Research Center, University of Hawaii at Manoa, 1974-09) Nomura, Myron M.; Young, Reginald H.F.
Heavy metals have long been known to exert toxic effects upon plants and animals at all trophic levels. Through the use of water as a cleansing and transporting agent, various types and forms of metals find their way into the sewerage system. To determine the fate of heavy metals sewage treatment processes, a study covering a period of five months was conducted at the Wahiawa Sewage Treatment Plant. The study involved determining the distribution of metals in the various fractions of the wastewater and sludges in addition to the overall removed in the system. The step-aeration activated sludge treatment process, employed at Wahiawa, removed most of the heavy metals, Al, Cd, Cu, Fe, Hg, Pb, and Zn, that were detected at the plant in concentrations ranging from a few parts per billion of mercury to a few parts per million of iron. Hexavalent chromium was removed somewhat less efficiently and nickel was reduced in concentration only slightly compared to the other metals monitored. Results of this investigation showed that most of these metals were removed by precipitation with the sludges in primary treatment and further removal occurred through biological uptake in the secondary phase of treatment. The residual concentrations of metals in the final effluent discharge were usually below toxic levels, with the exception of nickel, for freshwater aquatic organisms and plants.
WRRCTR No.80 Determining Porosity with Neutron Logs from Hawaiian Basaltic Aquifiers
(Water Resources Research Center, University of Hawaii at Manoa, 1974-08) Peterson, Frank L.; Sehgal, Man Mohan
Neutron count data for calibration purposes were collected by neutron logging in 4 boreholes, and porosity data were determined from photo logs run on the same 4 boreholes. A neutron count-porosity calibration curve was constructed and was found to take the form of the logarithm of neutron count versus porosity. The calibration curve was calculated by linear regression analysis, utilizing empirical field data. The calibration curve is valid within the expressed 95 percent confidence intervals only for neutron logs from (1) basaltic formations, (2) uncased hole8, and (3) borehole diameters from 20.32 to 30.48 cm (8 to 12 in.).
WRRCTR No.55 A Preliminary Survey of Public Water-Related Agencies in Hawaii
(Water Resources Research Center, University of Hawaii at Manoa, 1972-05) Morahan, Eamon T.; Yamauchi, Hiroshi
The governmental structure of Hawaii through which its water-related agencies operate is a relatively simple one as compared to that of most other mainland states. A highly centralized state government dominates over one layer of four county-level governments (in the case of Honolulu, the City &County of Honolulu). Each of these four local governments has its own charter which is similar in most respects to the others, but, nevertheless, uniquely applicable to itself. County boundaries are conveniently contiguous with the natural geographic boundaries of each island except for the tri-islands county of Maui (Maui, Molokai, and Lanai). Besides the four island counties, the only other local-level governmental entity is the Soil and Water Conservation District. There are some l5 of these SWCD's covering about 96 percent of the land area in the state. They, however, do not possess any taxing or regulatory powers and for administrative purposes they are closely associated with the State Department of Land and Natural Resources. While it is generally conceded that Hawaii has a relatively simple governmental structure, there are nevertheless a considerable number of public water-related agencies that has evolved over time. Some 50 odd agencies have been conveniently categorized under federal, state, and local agencies. While not all the higher level agencies in the federal category such as, the Water Resources Council, the Council of Environmental Quality, the National Water Commission, and the Office of Management and Budget, are physically represented in Hawaii, they still have important bearings on the water policies and programs of the state and so have been usefully considered along with those situated in the islands. Despite this broadened scope, the institutional coverage in this report is still somewhat limited by the fact that, except for the three quasi-public companies, which come under the purview of the State Public Utilities Commission, only public agencies were surveyed. Also, since the agencies are for the most part entities of the executive branch of the government, the roles of the legislative and judicial branches are likewise not adequately reflected. These public water-related agencies may then be regarded as only a portion of a complex institutional superstructure that functions in the water economy of Hawaii. Conceptually, this institutional superstructure is just as much a part of the total water resources system in Hawaii as the physical sub-system itself. From a social viewpoint, the physical sub-system exists for the ultimate benefit of mankind who has, through experience in conflicts, systematically developed the necessary institutions to facilitate orderly development and use of his naturally endowed water resources. In this sense, both the physical and institutional sub-systems make up the total integrated water resources system of the state.
WRRCTR No.54 Effect of Storm Runoff Disposal and Other Artificial Recharge to Hawaiian Ghyben-Herzberg Aquifers
(Water Resources Research Center, University of Hawaii at Manoa, 1971-11) Peterson, Frank L.; Hargis, David R.
Artificial recharge for the purpose of replenishing the fresh ground-water body in Hawaii has been deliberately practiced in a few areas for many years, and has been recognized as incidental to other practices, principally irrigation, in many areas for several decades. The effects of these various artificial recharge practices on Hawaii Ghyben-Herzberg aquifers are briefly described in this report. In recent years, the practice of artificially recharging wastewater such as storm runoff, sewage effluent, and various industrial wastes into the subsurface has become of growing importance in Hawaii. In 1970 the Kahului Development Company began construction of a collecting basin and four deep injection wells for the disposal of storm runoff from a residential development in Kahului, Maui. This presented a unique opportunity to evaluate the suitability of the site for artificial recharge and to study the possible effects recharge of storm runoff might have on the local ground-water body, both from a water quality and a hydraulic standpoint. Studies were made to determine the following information: (i) the concentrations of selected chemical and biological parameters in storm runoff from residential areas in the town of Kahului and in the ground-water body in the area of the collecting basin and injection wells for the purpose of predicting the effects of artificial recharge of storm runoff on the water quality of the existing local ground-water body, (ii) the injection rates that can be expected for the completed injection wells by means of pumping and injection tests, and (iii) the movement of the injected water by monitoring water levels and selected chemical and biological parameters at observation wells near the injection site. The results of pumping and injection tests of one completed well and one test hole indicate that the finished injection wells should be able to inject at rates in excess of 5500 gallons per minute per well if significant clogging from sediment does not occur, and if hydraulic interference between the four wells operating simultaneously is not significant. Water analyses indicate that quality of the storm runoff from the Kahului area is generally good, with low dissolved solids and low chloride concentrations. Some fecal coliform will undoubtedly be introduced into the aquifer during injection of storm runoff. However, dilution of the injected runoff by the ground water and the hostile environment presented by the saline water in the disposal zone should eliminate any bacterial hazard. The most serious potential water quality problem may be a reduction in injection efficiency owing to possible well clogging by heavy sediment loads. The general water quality effects of injecting storm runoff into the ground-water body will be to decrease the dissolved solids concentration of the ground water in the vicinity of the wells.
WRRCTR No.51 The Response to Tidal Fluctuations of Two Non-Homogenous Coastal Aquifer Models
(Water Resources Research Center, University of Hawaii at Manoa, 1971-11) Williams, John A.; Liu, Ta-Chiang
Mathematical and electric analog (R-C circuit) models for two one-dimensional non-homogeneous coastal aquifers have been developed. The first is a semi-infinite aquifer having a discontinuous change in permeability at a distance L from the coastline and the second is an aquifer of length L whose permeability changes linearly with distance from the coastline and whose interior boundary represents either a constant head op a no-flow condition. Both models were subjected to a sinusoidal tidal input. Results, in the form of graphs of amplitude and phase angle vs. position, show excellent agreement between the outputs of the mathematical and electric analog models. In the case of a discontinuous permeability, these graphs indicate a positive or negative reflection from the discontinuity for a decrease or increase, respectively, in the permeability. In the case of the linearly varying permeability model, the graphs of amplitude indicate that energy is attenuated at a greater rate near the coastline than K[sub]L/K[sub]O <1 for both types of boundary condition. Graphs of the phase angle are concave downwards for the constant-head boundary condition but for the no-flow condition they exhibit a point of inflection whose position depends on t[sub]o and K[sub]L/K[sub]O. Electric analog model results show that for the semi-infinite aquifer no significant error will result from the circuit configuration if a ≤ λ/50 and the circuit length is equivalent to 2λ, furthermore, "lumped" components, i.e., a = λ/5, may be used to extend the circuit beyond x = -0.4λ if measurements are restricted to x ≥ -0.2λ.
WRRCTR No.49 Thermal Properties of Sea Water
(Water Resources Research Center, University of Hawaii at Manoa, 1971-07) Chou, James C.S.
The interpolation formulae for vapor pressures, specific volumes, enthalpies and heats of vaporization of ordinary seawater have been determined in the temperature range 0° to 200°C for salinities of 0 to 120 pot, based on the published data. These formulae may facilitate calculations for designing desalting evaporators. The accuracies of vapor pressure data were found insufficient; however, the accurate measurements of vapor pressures by others are in progress. A close correlation was found between the compressibility of seawater and those of aqueous sodium chloride solution at low temperatures. Because the tack of experimental data on compressibility of seawater at elevated temperatures, compressibility of aqueous sodium chloride solution for pressures up to 350 atmospheres are used as approximations to those of seawater in order to account for the effect of pressure on other thermal properties.
WRRCTR No.50 Bibliography of Water Resources of the Hawaiian Islands
(Water Resources Research Center, University of Hawaii at Manoa, 1971-07) Pfund, Rose T.; Steller, Dorothy L.
Pertinent to the field of the water resources of the Hawaiian Islands there have been several previous bibliographies, but they are mostly out of date, and there are great gaps among their coverages. The need for a comprehensive, up-to-date, annotated bibliography was recognized soon after Water Resources Research Center began to function in 1965. In preparing this bibliography, free use has been made of the earlier bibliographies listed in the index. Especially helpful have been the Annotated Bibliography and Index of Geology and Water Supply of the Island of Oahu, Hawaii by Nora D. Stearns, Bibliography of the Geology and Water Resources of the Island of Hawaii by Gordon A. Macdonald, the bibliography in Coastal Currents and Sewage Disposal in the Hawaiian Islands by Paivo Laevastu, Don E. Avery, and Doak C. Cox, Index to Irrigation Investigations in Hawaii by H. A. Wadsworth, and unpublished bibliographies compiled by Robert Merriam and the USDA Forest Service.This bibliography is arranged in four sections: the alphabetical listing by author, author index, subject index, and the FCST category listing of the descriptors used in the subject index.
WRRCTR No.48 Direct Determination of the Electromagnetic Reflection Properties of Smooth Brackish Water to the Continuous Spectrum from 108 to 4 x 109 Hertz
(Water Resources Research Center, University of Hawaii at Manoa, 1971-05) Lepley, Larry K.; Adams, William M.
A new geophysical technique for the remote measurement of the electromagnetic properties of natural surfaces was investigated. Theoretical and laboratory work has produced evidence for the validity of the use of ultra-high frequency radio reflection spectrometry for remote sensing of salinity of brackish water. A preliminary study of the electromagnetic properties of aqueous sodium chloride, computer-generated frequency dispersion curves of 1) the dielectric coefficients, 2) power reflectance, 3) brightness temperature, and 4) skin depth of water as a function of eight different formalities of sodium chloride, corresponding to a salinity range from pure to ocean water and as a function of five different6 temperatures from 0°C to 40°C to the radio frequency range from 106 to 3 X 1010 Hertz were constructed. These graphs indicate that the frequency dispersion of the reflectance of radio energy in the 106 to 106 Hertz band at normal incidence to a smooth water surface is strongly influenced by the salinity of the water, and that the spectral signature could be used as a measure of water salinity as distinguished from water temperature.
WRRCTR No.46 Interpretation of Electrical Resistivity Logs in a Two-Zone Cylindrically Symmetric Geometry
(Water Resources Research Center, University of Hawaii at Manoa, 1971-03) Shamey, L.J.; Adams, W.M.
A two-zone theoretical model, consisting of a cylindrical borehole filled with drilling mud and surrounded by homogeneous, isotropic rock, was studied to aid interpretation of electrical resistivity logs. Apparent resistivities are numerically calculated as a function of the rock and the drilling mud resistivity and the separation of the electrodes on the coaxial measuring sonde. For practical use, the inverse, interpretation problem must be solved. Therefore, graphs for finding the true matrix resistivity -- given the hole diameter, mud resistivity, and electrode spacing’s -- are presented for ranges applicable to Hawaiian conditions. The interpretation may be done with the interpolative digital computer program provided.
WRRCTR No.1 Travel of ABS and Ammonia Nitrogen With Percolating Water Through Saturated Oahu Soils
(Water Resources Research Center, University of Hawaii at Manoa, 1967-01) Young, Reginald H.F.; Lau, L. Stephen; Burbank, Nathan C Jr.
A laboratory study was undertaken to determine the ability of four Oahu soils, Lolekaa, Lahaina, Manana, and Wahiawa, to remove ammonia, ABS, and coliforms from water percolating continuously through saturated soils. The soils utilized were chosen on the basis of their wide occurrence on the island in areas where percolating water may enter directly and in quantity into the ground water body that prinipally provides the island's domestic water supply. All four soils had a high clay content and low pH. All soils were effective in the removal of ammonia and ABS. One-hundred percent breakthrough for ammonia occurred after a throughput volume of 345 to 470 times the gross soil sample volume. For ABS it was 15 to 53 times the gross soil sample volume. The total exchange capacity for ammonia ranged from 29.3 to 50.1 micro-grams of ammonia per gram of soil. The total absorptive capacity for ABS ranged from 8.6 to 36.4 micro-grams of ABS per gram of soil. The applied concentration of ammonia was approximately 7.1 mg/l as found in a primary clarifier effluent and that of ABS was approximately 5.5 mg/l as found in a final clarifier effluent. The results of coliform removal from percolating liquids were not conclusive because of small soil samples and the loading procedures.
WRRCTR No.64A Preliminary Report on Flood Hydrology and Urban Water Resources: Oahu, Hawaii
(Water Resources Research Center, University of Hawaii at Manoa, 1973-03) Fok, Yu-Si
Studies conducted during Phase I of the "Flood Hydrology and Urban Water Resources of the Island of Oahu, Hawaii" project were divided into four major tasks. The first is an examination of the causes of flooding and flood damages on Oahu. This task has been completed and data obtained reveals that historical floods in Oahu happened most frequently within the city limits of Honolulu and the Waialua area. The second task was to evaluate the effect of urbanization upon flood hydrographs from selected watersheds in Oahu. The third task was to establish the rainfall-runoff data collection devices in the adjoined urban (St. Louis Heights) and natural (Waahila) watersheds. The installation and operation of two auto-recording raingages and two auto-recording water stage recorders were completed. The fourth task was to initiate the studies of watershed simulation models. Thus far, efforts have been concentrated on two watershed simulation models. One model utilizes an auto-optimal technique in determining the instantaneous unit hydrograph. The other model is a modification of the Kentucky Watershed Model to better fit Hawaiian conditions. Additional modifications are required before a good fit is achieved by both models.

Browse

Recent Submissions