摘要:

ABSTRACT: The impact of floodplain regulations on mean appreciation rates of residential land values was tested at six study areas in five counties in western Oregon. The study hypothesis that such regulations significantly depress appreciation rates of regulated lands relative to those of similar unregulated lands was in most cases rejected. When the hypothesis was accepted circumstances would render conclusions tenuous. The problems and issues facing this type of research are presented in case studies of two of the research study areas. The following factors challenge investigators seeking to resolve questions about the relationship between land use regulations and land values: varying degrees of stringency with which regulations are enforced; unequal assessment procedures between counties; influences external to floodplain regulations that may affect appreciation rates, including denial of permits for septic tanks, flood damages, and amenity values associated with waterfront locations; and the uncertain effect that the availability of flood insurance, which accompanies floodplain regulations, has on land values.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb04549.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT: In order to choose among “best management practices,” forest managers need to predict sediment yield to perennial streams following various forest land operations. The “universal soil loss equation” (USLE) is not directly applicable to forest operations because of the heterogenous soil surface conditions left by harvesting, site preparation, and planting. A sediment hazard index is proposed, to be based on the amount of exposed mineral soil and its proximity to streams. The model offered includes rainfall erosivity, soil erodibility and average land slope, together with the index W. A paired watershed experiment in the central Georgia Piedmont was used to estimate parameters in the model. The experimental basin (80 acres) was clearcut, drum roller chopped twice, and planted by machine. The standard error of estimate of sediment yield was computed to be about 50/lbs/ac per sampling period (four months). Use of William's erogivity index (storm flow times peak flow) reduced the standard error to 33

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb04550.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT: West Bitter Creek floodwater retarding structure site 3 in South Central Oklahoma was instrumented and records obtained and analyzed to obtain information concerning an impoundment water budget that is useful to landowners and designers of these impoundments. On‐site loss of water from the impoundment was only 17 percent of the inflow during three years when the annual precipitation averaged 26 inches and the annual inflow averaged 1.4 inches. Runoff from an eroded area with no farm ponds was about 70 percent greater per unit area than from a portion of the watershed where 71 percent of the drainage area was controlled by farm ponds. A previous study indicated, however, that the ponds were reducing runoff only 13 percent. Loss of top soil increases runoff considerably. Only 24 percent of the total runoff into the impoundment was base flow. The flow rate into the impoundment was less than 0.05 cfs 70 percent of the time, and the inflow rate exceeded 10 cfs only 1 percent of the time. SCS runoff curve numbers varied between 57 and 96 for the impoundment watershed with an inverse relation between precipitation amount and curve number apprently caused by partial area runoff from impervious and semi‐impervious areas. A comparison of measured event runoff versus event runoff computed by the SCS curve numbers gave an r2of only 0.44. However, the total computed surface runoff for eight years of record was less than 1 percent below the measured runoff which indicated the curve number method was a good tool for predicting long term runoff for the waters

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb04551.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT: Australia's extremely limited water resources highlight the need for policy guidelines for management. During the 1970s, there was the gradual evolution of a national water resources policy, facilitated by a nationally agreed statement of objectives and culminating in a federal policy statement presented in 1979. However, the Australian constitution gives major responsibility for water resources to the states. Further, the federal policy statement seems to assume that each state has a water resources policy and that it accords with the nationally agreed objectives. This is not the case, and the practical management of Australia's water resources falls short of the principles set out in the policy document. The River Murray, the nation's major water resource, provides ample evidence of this fact. With very limited water resources, Australia urgently needs to reduce the disparity between principle and practice in their management.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb04552.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT: We have developed a computer model of soil loss on an upland watershed from the continuity considerations for sediment transport and from equations describing rill and interrill erosion. The model is based on dividing the upland area into a grid containing rill and interill zones, on the Universal Soil Loss Equation (USLE), and on equations describing detachment and transport capacity of rill flow. The USLE estimates the sediment load from the contributing areas. The location and amount of total erosion and deposition are determined by comparing the transport and detachment capacity of rill flow for specific storms. The model considers the mechanics of erosion process and can serve as basis for reservoir and channel design and land use planning.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb04553.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT: The analysis of stream flow and several water quality parameters in six Illinois rivers showed both deterioration and improvement in quality indicators during 1976–1977 drought. The adverse impacts were an increase of ammonia and manganese concentrations and, to a lesser degree, increased concentrations of phenol and specific conductance. At the worst point during the drought, the 12‐month moving average of monthly ammonia concentration in the Sangamon River was about 620 percent higher than the antecedent value. On the other hand, average concentrations of nitrites and nitrates, total iron, and the number of coliform bacteria significantly decreased. This positive response suggests that streams which are considered unsuitable for municipal supply due to high levels of these quality indicators may be used as emergency sources during droug

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb04554.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT: This study tests the hypothesis that climatic data can be used to develop a watershed model so that stream flow changes following forest harvest can be determined. Measured independent variables were precipitation, daily maximum and minimum temperature, and concurrent relative humidity. Computed variables were humidity deficit, saturated vapor pressure, and ambient vapor pressure. These climatic variables were combined to compute a monthly evaporation index. Finally, the evaporation index and monthly precipitation were regressed with measured monthly stream flow and the monthly estimates of stream flow were combined for the hydrologic year. A regression of predicted versus measured annual stream flow had a standard error of 1.5 inches (within 6.1 percent of the measured value). When 10, 15, and 20 years of data were used to develop the regression equations, predicted minus measured stream flow for the last 7 years of record (1972–1978) were within 16.8, 11.5, and 9.7 percent of the measured mean, respectively. Although single watershed calibration can be used in special conditions, the paired watershed approach is expected to remain the preferred method for determining the effects of forest management on the water resourc

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb04555.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT: The pressure on water resources from energy resource development and transformation is likely to be greater in the future than it has been in the past. A rational resolution of the political problems that this situation will generate requires that: 1) planning based on predictions of future energy supply and demand be replaced by scenario, or “what if?” analysis; 2) full attention be paid to the uncertainties in per‐unit‐energy water requirements; 3) suitable stochastic measures of water availability be used to compare water supply with water demand; 4) realistic ecological criteria, and other alternative use criteria, be developed for estimating impacts of water withdrawn or consurned for energy development; 5) human consequences of ecological impaccts are described in a manner that will allow the political process to intervene in an optimum manner to allocate water re

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb04556.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT: Clearcutting aspen from the upland portion of an upland peatland watershed in north central Minnesota caused snowmelt peak discharge to increase 11 to 143 percent. Rainfall peak discharge size increased as much as 250 percent during the first two years after clearcutting, then decreased toward precutting levels in subsequent years. Storm flow volumes from rain during the first two years increased as much as 170 percent but declined to preharvest volumes in the third year. Snowmelt volumes did not significantly change. Snowmelt peak discharge occurred about four to five days earlier after clearcutting, but the timing of storm flow from rainfall was not changed.Snowmelt peaks remained above precut size for nine years after clearcutting on an area undergoing natural regeneration to aspen saplings. Partial cutting ‐ up to approximately one‐half of the watershed ‐ reduced peak snowmelt discharge because melt was desynchronized in cleared and forested parts. Clearing more than 2/3 of the watershed caused snowmelt flood peak size to double during years with snow packs in excess of seven inches of water that remained until a day when maximum air temperatures exceeded

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb04557.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT: Ideology has predisposed the People's Republic of China against the use of prices to allocate water. Prolonged drought in north China has made the Chinese more aware of their unfavorable water resource inventory and the expense of expanding supply. Therefore, as part of the economic liberalization commenced since the death of Mao Zedong, China has started to make more active use of pricing to regulate demand and reduce the need for supply expansion.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb04558.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY